Cafe Scientific, Southampton, UK, past talks , end of 2015

Latest update of this file 13 December , 2015

Some details on past SWA science cafe talks in 2010 , including transcripts of talks and Q&A
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Some summaries etc of past talks held at the venue, The Southwestern Arms (upstairs room) , 36 Adelaide Rd, St Denys, SO17 2HW
Some hosts are not alowing remote linking now , so to view a "forbidden" picture you have to right click on the mouse and select "view". Not verbatim, and there will be homonyms, transcription, transliteration, typing and spelling errors and misattributions in the following write-ups. Q&A , grouped under one "Q" or ? terminator tend to be dialogue with / multiple questions from one enquirer. ? for unheard / masked words , ??? for phrases.





Monday , 12 October 2015, Dr Ivo De Medeiros Varzielas , Particle physics theory, using symmetries to try to explain why there are 3 copies of each particle. Abstract: I will start by going over what we currently know about particle physics - what is referred to the standard model. The standard model is extremely successful but there are motivations for going beyond. These include the matter/antimatter asymmetry, the existence of dark matter, and the existence of 3 generations of fermions, which I will describe briefly. I will then cover some theories beyond the standard model which address these shortcomings, focusing on what is referred to as family symmetries that aim primarily to explain the fermion generations. 2 hours, 42 people Maxwell the grandfather of particle physics. This Scottish physicist unified with his equations 2 seemingly separate interactions between electricity and magnetism, now called electro-magnetism. His equations are just over 150 years old. Paul Dirac, one of the fathers of particle physics. One of his major contributions was that he derived a relativistic version of the Schrodinger Equation, so consistent with relativity as described by Einstein. Through this equation, even before antimatter was observed , it was predicted. I would say his accomplishment was on a par with Newton and Einstein, but less known. He was interesting as a person as well. A list of names of people in the field. Bohr, Bjorn, Shadwick, Debroglie, Dirac, Einstein, Fermi, Heisenberg, Pauli, Plankh, Rutherford, Schrodinger and Sterne. Particle physics perhaps more than other areas of science is a science without borders. We have CERNE which is located across Switzerland and France an amazing international colaboration. Historically, physics is rather male dominated and particle physics even more so. So some distinguished ladies, Marietta Blou, Marie Curie, Louise Magna, Chen Choo Hoo . Cecilia Zcaskov, retired now. A theorist Liza Randell , Flaviola Gionotti of Cerne will become the first female director of Cerne. Melissa Franklin, particle physicist the first tunured physics professor at Harvard. I wish to make the point that all modern technology like computers, TVs etc relly on the understanding of electromagnetism and quantum electrodynamics. Maxwell's equations did not have immediate practical application. But modern technologies have rellied on him. A good argument for governments to fund fundamental research as private companies ar enot so interested in it as it is long term. For instance the WWW was invented at Cerne. The Standard Model. What are quantum-field theories. What is a field in this context. Its a physical quantity that has a value everywhere. Weather-related examples. So scalar-fields that is just a number like temperature. Not just one temperature but different temps in different places. So in this room I could map out the various temps and then say I have a temperature field. Pressure is another scalar. An example of a vector-field would be wind velocity, at each point there is not just a value but a length/direction. Our models of particle physics are field theories , so they describe quantities that have values everywhere. But they are not classical, they have weird behavior of quantum physics,that is not intuitive. Classical electromagnetism is classical field theory. Becaus ethere is a value for the electric field at each point, or value of a magnetic field at each point. So with a powerful magnet, measuring the field close to the poles , is stronger and might be pointing in different directions and varies as you move away from the magnet. One of the simpler examples of a quantum field theory is called QED, Quantum Electro-dynamics. I think it was Feinman who termed it that, partly after the Latin QED meaning. Basically QED describes electrons , one type of fundamental particle, how they interact with one another, by exchanging photons, photons are another fundamental type of particle. Most of condensed matter physics is , we say from first principles , from QED. So what are interactions. In macroscopic life we are not so used to this. Particles interact by exchanging particles. 2 boats, a person on one and a frog on the other. The frog throws a ball to the person and the boats drift apart due to this. The boats don't touch each other but there was an exchange of a ball . Q: How do you get an attractive force with that model? Thats exactly the question I wanted. That and why is there a frog on top of a boat. This analogy works better for repulsive forces. Q: Which particle is which in the diagram. The exchange particle is the ball and the other particles are the boats. The person and the frog are just helpers. You can have similar situations with skaters, exchanging a basketball. Or 2 people on skateboards. Whenb the frog threw the ball, he went backwards as he threw the ball forwards and when the person receives the ball , he moves backwards. Q: When you talk of a field can you say , does the field contain energy or the particle contain energy ? At the field theory level as in classical EM, the energy is contained in the field. The EM field squared + EM field squared plus some ? factors. In particle physics thats also true if you look at it from the fieldtheory point of view. But quantum electron-field is not an electon here , all the electrons in the universe are part of the electron-field . Thats why you can create them out of thin air , so to speak. Everywhere there is the electron field and just when you excite that field , locally pump some energy, that you can get a particle materialising. Electrons , we think of as particles, are just localised manifestations of the field. So a one dimension string, laying static, I can touch it locally and wiht that energy it can oscillate. QED , describes electrons and photons but the standard Model ,SM, , we go a bit beyond it these days but not that much. Its also a quantum field theory but instead of just describing electrons annd photons it describes the remaining fundamental particles that we know about. The list for QED is a smaller list than the SM, more stuff and more interactions. If you know how to build quantum field theories, not that simple, once leant not that complicated. The interactions are encoded in what is termed a symetry , a U1 symmetry. A U1 symmetry is basically a reflection of electrical charge. It encodes , if you have + and - charges and you are going to conserve them. The symmetry is encoding the conservation of charge. Then there is more intricate mathematical methods we use to make this more precise. The SM model has interactions encoded in different symmetries. Similar to U1 but not quite the same , with names SU3, SU2 and U1. They are related to the properties of 3x3 matrices , 2x2 or 1x1 which is just a number. In SM, the U1 symmetry there is not directly the U1 symmetry of Electromagnetism. My list , electrons , neutrinos sort of like electrons but very different, up-quarks and down-quarks which are different to electrons but similar in other ways, then stuff like photons , so photons ,weak bosons and gluons (after glue). We physicists like funny names for some stuff. I'll focus on interactions of the SM. Firstly, gravity is not included. Compared to gravity , the weak bosons are really strong. Gravity at the particle physics level is really weak. Possibly why we don't understand it well. At the current state of the art we don't have a good understanding of gravity aty the quantum physics level. We have a theory that is now over 100 years old , general relativity. It works really well , and if it didn't then stuff like GPS would have an accuracy of km . The SU3 interaction I've designated here as a colour , not colour in the usual sense of our eyes and seeing photons. The colour here is a name physicists use . In comparison to EM where there is + and - charges, for SU3 there is 3 properties related to the 3 inside the bracket and physicists decided to call these red,green and blue. The SU2 interaction has subscript also. U1 is now hypercharge and not EM charge These terms have a precise useage amongst physicists , but not necessarily their usual meaning in the wider world. SU3 is called the strong force. Its very peculiar in comparison to all the other forces we are aware of , including gravity, because its a force that becomes larger at larger distances. An analogy there is a spring. If you try to pull a spring apart , you feel more and more resistance from the spring. Gravity is the othe rway round, so is EM. Because of this property of the force becoming stronger at larger distances , these particles ??? , the coloured particles in this nomenclature , always appear in real life as colourless combinations. So even if you might have a particle thats red, another green , another blue, they will always appear in combinations so that 3 of those are together so when you look from afar, it does not look red/green or blue but white. Such colourless combinations as that are protons and neutrons which are the nuclii of atoms. They are not fundamental particles, made of particles of colour but because of this property of the strong force they cannot appear by themselves. The weak force mostly associated with SU2, not really weak , it looks that way because the symmetry that is associatred with it , is broken, described a bit later. SM matter . The fermions are a name for it after Frederico Fermi, in hte SM they have a spin of 1/2, this spin isa property of the fundamental particle . Considering angular momentum, like a ballerina spinning with arms open, so some angular momentum, then she closes down her arms , she spins faster , but she still has the same angular momentum. Because of less distance from the centre of rotation. That is understandable because a ballerina is an extended body and you can see rotation. The problem with the particles is that they're point-like , what is rotating around anything if its just a point. Yet it has an angular momentum, that can be measured. In the most natural units you can choose for that quantity, you cant have arbitrary quantities of angular momentum but only multiples of one half. So you can have 0, 1/2 or 1 . For big stuff like people , you can have a contiuum of amount of momentum . But at these scales the unit is so small you would not be able to see a difference. You cannot have less than 1/2 and more than 0 . The fermions of the SM all have spin of 1/2. The quarks, coloured, interact withthe strong force because they are coloured. Other particles, leptons, that are not coloured , like electrons and neutrinos. Beyond that it gets more complicated. Each of these particles appear in 2 versions and that is before going with antimatter. So one of the interections is called SU2(left). Returning to the spinning ballerina, if I'm spinning one way , with a right hand out and fingers one way , my thumb is going up and the spin is defined as "up" . Spin the other way round and the angular momentum is defined as down. Or I can spin in the same direction but now with my left hand out. So 2 versions, called left-handed , with spin 1/2 can be pointing in the direction they are going . Right handed is the opposite. You can think of an electron that is lefthanded and one that is right-handed, but they are not really the same particle at all . Only the left hand ones interact with the weak force. Hence SU2(left). There is a matter particle with spin 0, in our nomenclature we also call that a scalar. It interacts with the weak force but as 0 its neither left or right handed. Its this that breaks the symmetry, and that is why the interaction appears to be weak. It does so by having an internal direction in SU2 that is pointing everywhere. A summary table showing the neutrino and electron that are left-handed are parts of an object which has 2 components, thats why its SU2, it interacts under SU2left and under SU2 if it wasn't broken then the two would be in a sense the same particle , part of the same object, its not dissociated. A right-handed elctron . The neutrino and electron that are left-handed are black , the electron is also black, no colour, no interaction with a strong force. There are up-quarks and down quarks they appear in objects that are 3 dimensional ,in the sense of red,green and blue one, but also because the left-handed ones are parts of objects, they are 2D. 6 different versions of it bu the same object. Whereas the right handed one , which does not interact with SU2left is only 3D in that sense. Not 2 or 3D sense of space , but in ther sense of the same object being represented. Q: Can you explain how you would tell whether an electron was left or rightr handed? Its not easy because the symmetry is broken . Any time there is radioactive decay its an action of the weak interaction. There is involvement of a left-handed one there. With the broken symmetry, what electrically will happen is that 2 guys separate and associates with another guy , at that stage when the symmetry is broken , is when an electron gets a mass. Q: The middle column , is that a potential particle or just a concept that doesn't exist ??? A field of up-quarks which have the following properties its an object that under SU3 , the symmetry that is the strong force , has 3 entries , like ?, and under SU2 has none, its like a vector in 2 dimensions. You cannot say you only want the x-part of a vector , you have a vector. This object is one object. Its only when symmetry gets broken that one half separates from the other half. There isa missing bit where you would put a righthanded neutrino , which is not a part of the SM, but probably is part of reality, now that we know that neutrinos have masses, since 1998. The next slide is more complicated . Previously I showed one generation but SM has 3 generations. Again the terminology is not the usual meaning of a generation but is mindful of that concept. 3 people who more or less share some properties, 3 women of 3 generations. They all like to wear white, the faces look somwhat similar. In SM the 3 generations are almost identical equal except for the mass. The mass only appears after you break the SU2 symmetry and allow the halves of these 2D objects that were connected, to connect with the other bit , which was not there. I will have the 2D vector of SU2 that wants to connect to something that is not a 2D vector of SU2 and it cannot. It can only do that with something else that is a 2D object of SU2 which is in fact the Higgs Field. The Higgs field has a sort of potential which is mentioned a lot like a Mexican hat or a wine bottle base. It isnt stable and wants to fall to one of its sides at that stage it gets a vacuum expectation value , breaks the symetry . Then the left-hand guy, the right-hand guy , for example the up and down quark that are left-handed on one side. When the symmetry is broken , the up and down quark , are now different, different masses because you connect the left handed up with righthanded up and form a different configuration. They have a mass and no longer have a well-defined handedness. Something with a mass no longer has a well defined handedness. While it didn't have a mass and was going at the speed of light . Some comments on neutrinos. Day and night 100 thousand million neutrinos pass through your thumbnail every second , and you never felt a thing. On average , during your lifetime , only one of those neutrinos will interact with your body. Q: The spin not being defined as they gain mass? Spin in as intrinsic property that particles have. What is defined is their handedness . When a left handed bit and a right handed bit are not interacting , in a specific way, that they acquire mass , they're massless and travelling at the speed of light. So if SU2 is not broken they are travelling at the speed of light. If travelling one way the spin can eithe rpoint one way as a righthanded particle, or spin point the other way and its then a lefthanded particle. As soon as it acquires a mass by interacting via the Higgs mechanism, becoming a massive entity , which we usually call the electron because it has a well defined mass. An electron with mass is no longer travelling at the speed of light , and I can overtake it or not, then I cannot define its hand. It still has spin that I can measure . It becomes relative to the frame of reference when it has a mass. Thats why it was a tricky question earlier on, as to how do I measure a lefthanded or a righthanded electron. With symetry broken, I cannot distinguish in that way. Because all electrons are a bit of left handed and a bit of righthanded. Q: Relating to Higgs. Courtesy of Cerne , the belief now is that we've proved it exists experimentally. From the theoretical point of view have people been working on the assumption that the Higgs field exists in order to do calculations with the SM or has it been hanging fire, pending ? It was almost completely accepted that there was something , exactly in details for example one or more Higgs fields for example. This we still don't know or something that just mimics a Higgs Field, but is not afundamental scalar , spin 0 ,for example. There are some theoretical problems associated with that. We knew there was something that would play its role at least. The SM by definition is one Higgs Field and thats it. There are beyond SM theories, something else or instead. Many of the things don't depend on htat at all. Q: When you have a left and a right, upquark or down quark? All of them except the HF, have a left and a right except possibly the neutrino. For an upquark it has a left and a right, is that similar to what is called a quantum superposition, a spin up and a spin down. ? After the symetry is broken and aquire mass each physical state will be a bit of left and a bit of right handed. But only afte r it broken, before breaking you could distingu=sh left and right handed . How do we know. A picture of a cat , or there was a cat, the dry outline of a cat , on damp ground , before the cat decided it didn't like the wet. A cat-shape absence of rain. You indirectly figure out that there was a cat there , before you came along. I can infer there wa s a cat there, even though I never saw a cat. The first time neutrinos were confirmed was I think 1956, this pic of 1970 at Cerne, using a hydrogen bubble chamber. Imagine a pool table, you see the balls racked, you don't see a cue ball . At a certain stage the balls scatter , an invisible cue ball hit them like that. The chamber full of protons , something happened because it was from a particle that was not tracked , something without charge. A proton started here, moved there and then did something else. Something sprouted from nowhere , a mu-meson the relative of an electron , a heavy elctron . Then there was another particle that is not a fundamental particle , made of up and down quarks , went there , a pi-meson, an upquark and a down antiquark. The interpretation is that an invisible neutrino , came along, but rarely interacts with a proton , emitted a W-bozon, a weak bozon , very short lived and almost instantly became the pi-meson. The neutrino converted itself into a muon , the proton just got kicked a bit. You didn't see anything but something happened , but you can infer something was there , like the wet cat. Neutrino oscillation and more recent measurement of neurtinos. The Nobel prize for physics in 2015, for the observation that neutrinos had mass. Proven by neutrino oscillation. A Japanese and an American, experiment performed in Canada , called SNOW. The Japanese detector is really big , a big tank, filled with water , surrounded by photomultipliers. Then observe any neutrino interactions. The other detector, smaller , SNOW detector, filled with heavy water , so more interactions with neutrinos , for a given volume of water. Another detector a 1km cube of very pure ice, deep down. That experiment called Ice-Cube. That works on similar technology. Measuring neutrinos from the Cherenkov Rings, that are left, not by the neutrinos but from the particles of the weak interaction. In the hydrogen bubble chamber , the neutrino became a muon ect. If the muon is travelling in water or heavy water or the ice. Its travelling above the speed of light in that material, not above light speed in a vacuum. As far as we know that is impossible, despite what appeared i nhte news a while ago, not my mistake. You can get speeds higher than light speed in materials. An interesting experiment where they slowed light right down , condensed matter stuff. When something goes above the speed of light in a material there is Cherenkov radiation, which will produce very typical rings. You can use it to infer properties of your original neutrino, you can gauge the speed of the muon or the electron . Its easy to distinguish an electron from a muon , therefore a muonic neutrino from an electronic neutrino from the characteristics. Muons travel straight and make a well defined ring wheras the electron creates an electromagnetic shower . So not a single particle making Cherenkhov rings, but more than one. For the muon one there is a well defined ring , with well defined edges compared to the electron event where there isa lot of scatter. Q: Are the spots on these diagrams , where individual detectors have fired? Yes These are from the Japanese detector setyp. Like a cylinder opened out . Sharp rings - muon event, fuzzy rings - an electron event. Cherenkov radiation is similar to when an airplane goes over the speed of sound in air. You can do it when cracking a whip, the tip of the whip surpassing the speed of sound in air. Pic of a plane creating a sonic boom , a conical shape in the condensing vapour Q: Why does passing hte speed of sound affect the way we see things? Sound is vibrations in hte air . Tips of airplanes create a turbulance situation , sometimes you see whirls , from water molecules that are in the air that condense out when there is perterbation, forming a sort of small cloud. I was wondering if anyone would ask , how we get the Cherenkov effect forwards , if the cone looks backward. Also in the plane analogy the sound travels forward. Q: The particle causing the radiation is giving up energy , why does the diameter of the rings stay the same as that energy decays away? They are going above the speed of light in that material so quite energetic. The thickness of the ring, when it was created , it started emitting, travels and keeps emitting , then leaves the detector and you don't see it any more. So there is a thickness to the rings. Q: Does the muon-nutino only decay into a muon and never decay into an electron, as some sort of conservation #of spin? Yes its related to SU2 . In the SU2 objects , the muon-neutrino and the muon are in a single object , you never have a muon-neutrino become an electron. In the picture of the sonic boom , why the cone is backwards rather than forwards. The Cherenkov cone is forward . A pic of a swan , not moving beyond the speed of sound , but moving above the speed of propogation of surface waves in water. Same with boat wakes. If you close your eyes , place your hands in the water , it hits your hand going forwards but it looks like a cone going backwards, but its propogating forward. Symetries Neutrino Oscillations. 2 simple bass bob pendulums on equal lengths of string, tied to a horizontal string, between 2 retort stands. Spaced about 1/3, 1/3, 1/3 and support string allowed to sag a bit. One bob I hold represents the electron neutrino and the other is the muon neutrino . The electron-neutrino and the muon-neutrino don't have well-defined masses. They have well defined flavour. They are well associated withthe electron or the muon, but not qualifying masses. When they travel, as they don't have well defined mass , they don't know what to do, they express themselves in terms of the neutino with well-defined masses that then travel. as they are travelling with different masses they will shift energy from one to the other. I started oscillating one of these bobs and eventually the other started oscillating and the first stopped , then it all resumed. This happens because there is a string connecting them, for the transfer of energy. This is a good analogy for what happens with neutrino oscillations. In the Sun for example or in a reactor , you produce electron neutrinos because the reactions involve electrons and upquarks and ? quarks . The electron-neutrino when fisrs tcreated , was purely electron-neutrino but then it travels to the detector . As it travels ,say sun to Earth, it needs to know how to travel and it needs to know its mass. This is expressed in maths as a linear combination of the mass-Eigen state. There are 2 flavour Eigen states, the electron neutino and the muon neutrino and it needs to know what arte the mass Eigen states. The 2 bobs each have a well defined oscillation frequency. Analagous of the 2 mass-Eigen states. However , when I start one of the bobs on itself. I'm subtracting one part from one state and adding part to the other state. With different oscillation frequencies, at certain times it passes all over to the other flavour and so on. Q: what would correspond to the string doing the coupling in the physics ? The coupling is the SU2 interaction and the mass is the interaction with the Higgs Field. If they are right handed neutrinos, we don't actually know, there is an interaction between a left hand neutrino and a right hand neutrino. There is probably 3 of them, but imaging there is just 2 of them. 2 left hand neutrinos and 2 right hand neutrinos , they interact and get mass. But there is also 2 left hand neutrinos which one of them only reacts with an electron and the other only reacts with a muon. Bu tthe guy who only reacts with the electron might not be the same combination or configuration as reacts with the right handed one. For me its easier to see with matrices. This is only when they have masses, if they only had weak interactions , then there wouldn't be the "string" and oscillating electron always stays an electron. But with masses they have another interaction which you can sort of compare with another. It could happen that they would be the same states, but its not, then they can exchange in their different combinations. Q: Neutrinos interacting with the HF, aqiure mass , and can oscillate? Yes The other part is about symmetries. An eqilateral triangle with lines drawn on it. If I give this to you as drawn on paper and I put it on hte table. I'll turn my back and you do something to it , I turn back, and I want to be in doubt as to whethe ryou've touched it or not. You could move it a tiny bit and hope I did not notice , but you could do a big change and I would not know. You could turn through 120 degrees. This is a symmetry. An equilateral triangle has 6 symetries , you can rotate 3 amounts or take a flip around a bisector line. A mirror symetry because its much the same as putting a mirror along a bisector. The other is a rotation symetry. If I squash the triangle to a pointy one, it still has some symetry as an isoscilles triangle. You could leave it alone or flip it around the bisector line. With an irregular triangle the only symetry is leaving it alone, moving by 0 degrees. If I do something to an object and it remains unchanged then its a symetry. To construct objects thaty are invariant under various symetries from bits that in themselves are not invariant under symettries. If I gave you 2 off, 90 degree triangles and asked you to join them to make an object with more symetry , you could join them to make an equilateral triangle, so more symetries than the constituent parts. Each of the parts have the symetry of leaving it alone, but combine them as an equalateral and there is more symetry. Returning to particle physics , fermions have spin of 1/2, as well as the symetries of the SM there ar ealso translational symetry which are associated with the Lorentz Group , the conservation of energy and momentum . In order to have an object preserving this sort of important symetry then the complete object does not have spin. When you write your theory you have to have something with spin 1/2 related to something else having spin 1/2, eg one pointing up and one pointing down. I can construct something with bigger symetries , from other constituent halves. Example of square brackets in an image from which I can make a rectangle or a square, having more symetry than the square bracket. Or minus signs , I can add another to make a plus sign and a plus sign has the same symetry as a square bracket. The scalar product of vectors , a vector in 2D space , I could describe it in terms of 2 co-ordinates , I know the length of that vector is a number and it does not depend on my frame of reference. Mathematically I can construct the length of this vector from x^2 plus y^2 and sq root. An example of a scalar that was built out of a vector , I did it by taking the scalar product . If I used 2 different vectors x1,x2 plus y1y2 so the length and the scalar product of 2 vectors are frame independent quantities. I can do a rotation or change the frame and these quantities do not depend on that. Important as any physics should not depend on the frame of reference, here or in Australia. In physics you need to construct things that are invariant under various symetries. All the different fields or particles have transformation properties under different reactions, like SU3,SU2 and U1 etc. The interactions of the particles respects invariant combinations. One way for seeing htis is in EM, where this restriction that the theory is inveriant under U1 of EM, is directly related to the conservation of electric charge. In electrical engineering, if you have some current going here, it splits into 2, you hav e to conserve the currents, etc. If you have a more fundamental process like , if you create an electron out of thin air, as its a quantum theory and you can do that with enough energy, then you also create a positron , the antiparticle of the electron and has plus charge. So you cannot start with something of zero charge and end up with something that was not zero charged. That conservation of charge is coming, precisely, because of the conservation of symmetry. In asimilar way i mentioned Lorentz symetry that is related to the conservation of energy and momentum. The Lorentz symetry is telling you that if I have something here or something a metre away there, or if I rotate it the process should be the same. Translational invariance or rotational invariance , symetries that physical theories have, and associated to theories of conservation of energy, conservation of angular momentum and conservation of ?? A bit about my work. I'll go a bit beyond the SM. The SM has proven to be wrong as we now know neutrinos have masses and as it was defined in the 70s, no righthanded neutrino and nothing else that would have given neutrinos masses. Since 1999 know otherwise. The pictur eof 3 women , 3 generations. I want to convince you there is something unpleasant about the SM. It could be seen as a list, but its an unreasonable list because just looking at the uptype quarks , one of the fermions that we have. There is 3 generations of them , one generation is the top quark, the charm quark and the other is the up quark, which is the lightest one , inside protons. If you measure their masses , they are completely identical, the same properties under SU3 , SU2 and U1 but if you measure the mass which in the SM is coming from interaction with the Higgs particle. You measure the mass in GeV , popular units in particle physics, but imaging in Kg just for now. This one has 170,000 units of mass , this one 1000 units and the other has only 1. So completely different to particles that are otherwise identical, very strange. For the 3 women in that 3 generations pic, I decide to throw a party. I give them fruit, 3 blackberry drooplets the little bits in a blackberry, 3 black grapes , 3 limes and 3 oranges. 1 of each for each person. So black stuff and coloured stuff. So my neutrinos, my electrons, upquarks and downquarks which are coloured. So if I decided the young one was still growing so give her an orange the size of the moon. For the old-generation woman a metre size orange and the middle generation a 1km orange. This would not be reasonable. In nature there are large fruit and small fruit but they have no relation. 950Kg pumpkin and the smallest fruit , a relative of the duckweed its fruit is very small . You might have a big grapefruit , then a clemantine , then a clemantiny . You can get different sizes but not of the magnitute for the analogy with the moon-size. 3 generations of fermions, the hiarchy of the masses. In the first line are the uptype quarks. A linear scale in GeV, each peak adding 10GeV, 0 to 50, to 100 , to 150 , the top quark is the heaviest fermion, about 175. So use a logarythmic plot so each peak is multiplying by 10 rather than adding 10. So quickly go from milli-eV 10eV, the top again at 175. The charm quark at the Gev units sort of size. In the down quarks there is a heavy one in the bottom quark In the electron particles there is the Tau also at the GeV scale. In the logarythmic plot there is some sort of pattern that might be there, or perhaps a coincidence. A third generation that is heavier then a bit of a jump to the second generation and anothe r jump to the first generation. The neutrinos are weird and right on the other side. The combination with a well-defined mass is not ther same combination with well defined weak interaction. The mixing between the welldefined masses and well defined interaction , in the quarks is often the same , particularly for the third generation. The top quark and the bottom quark , their mass-eigen states are almost exactly the same associated stuff in the 2D objects that interact with SU2. There is a bit of mixing between the first and second generatins. The lightest down type quark , the down quark , has a little bit of the state that interacts with the charm quark which is the second generation of the up type. Pi charts showing the mixings. In the leptons , involving mixing of the electrons and neutrinos and their other generations, it is peculiar because the mixing is very large , it takes seemingly peculiar values. One of the mass-eigen states is almost half the tau-neutrino and half muon-neutrino . The second Eigen state is almost equal parts of all 3 , and a left over combination, because you need to have as much blue as a full pie. In the electron sector we say , the 3 generations of leptons you have large and peculiar mixing angle, because you can parametise these things as angles. So weird, also weird as 3 copies, and weird as all 3 have very different masses. So the point is , what if the 3 generations started the same. In real life all the generations start young , one is old before the other begins life. What if they are all young and there is something splitting them apart, as though they were born in different times. This is what i work on. Its one of the possibilities of going beyond the SM. Its called adding family symetries because they inter-relate the different generations. You could have another SU3, involving 3 objects. If you added it and insisted it was there, then what happens. If you insist its a symetry then all the masses along one of the types of particles , the 3 generations have the same mass , the up, the charm and the top would have a specific mass. The bottom, the strange and the down would have another specific mass. The elctron, muon and tau would have another specific mass. But there wouldn't be 9 different masses. You could have different masses between the up and down quark but between the up, charm and top , they wouldbe the same. But this is not what we observe. If you add the symetry , you also need to break it. You can do that similar to what we know with SU2 weak interaction. So you have scalar fields, like the Higgs field, slightly different. You have a field that is transforming under one particle , which obtains an expectation value and a kind of ? . And then it breaks the family symetry and it is like squashing a triangle. Now the colour is like the mass of that particular generation and then break it in steps , first by breaking the mass of the third generation to the more massive and then the others would still be equal masses. Another would break SU3 to a SU2 because the same mass, so some still preserved symetry. Eventually you have to break it all. Technical details of the model is what I work on. You can arrange this from adding the family symetries , SU2 to SU3, adding some scalar fields , writing down the theory according to the rules of quantum field theories, looking to see what the outcome is. A way to understand why the different masses occur. Q&A What is the history of why the choice of a half for spin, it seems silly for that value? Fundamentally it doesn't seem important as its a question of normalisation. There is a big difference between particles that have fractional spin and ones with integre spins. SM fermions all have spin 1/2, and multiples of 1/2. Behave very different to articles with spin 0,1, 2 which are bozons. Fermions after Fermi and bozon after Boze. With bozons you can have as much of them , in the same physical state, eg the same energy , same momentum and co-exist. Wheras fermions , if you have one wiht one particular state of energy , momentum and the spin pointing up for example, you cannot have another one i nexactly the same state, it doesn't happen. This is what happens in atoms for example. For atomic orbitals, they have like slots , becaus ethe electrons are couple to the E-M field , they are bound , and can have very well defined states of energy. In that case not just the spin that is quantised but also the energy levels. Then for any particular energy state you can have electrons, one would be spin up and hte other spin down , and no more because they are fermions. If they were photons instead of electrons then you can have many of them in th same state. That is what is used in lasers, also where you quantise energy states , promote to the upper energy state, let them decay and then you have lots of photons in exactly the same energy state, a very well defined beam of light in that case. Thats why its useful to keep the normalisation factor to one half. I seem to rmember in the atomic quantum orbital world , where things have an angular momentum of 1,2 or 3 that got stuck . Then it was found individual particles came in units of half as much , but things were previously fixed? Historically thats correct. You can also why, with commonly available electrons, why are they defined as having negative charge perhaps they could be termed positive instead. Physically it makes sense to keep this difference , every other choice , the physical properties really change a lot. Ther one with 0 cannot be normalised to something else. Multiplying it by anything and its still 0. Those , bozons, like scalars. Also you can have 2 electrons coupling together i na specific way in superconductors in Cooper-pairs. Because they are together they are also a bozon. You can have several electrons in the same state becaus ethey are associated in Cooper-pairs. You said ? was ? part of the SM. Is that because of experimental evidence of things like spooky action at a distance, quantum entanglement, are those parts? Thats a differnet effect. Its not a quantum field theory, just a quantum mechanical effect. It was like I was showing with the pendulums , there are situations where you can have a physical state which is superposition of different states, and then you never really know which one it is until you measure it, but after you measure it , you've completely perterbed the state. What happpens in entanglement , and also in particle physics, it might be that you produce mesons for example. Mesons are similar to protons but instead of 3 quarks , each of which is one of the 3 colours, it will be a combination of a quark and an antiquark oine with a colour and the other the anti-colour. They are still white in the sense that they are colourless but just a ???. There are situations where you can have a decay , mesons into othe rmesons and you don't know which one is which. But if you observe one then you automatically know what the other one will be , before you measure it , because of entanglement. Its like where one must point up and one point down and eventually , you measure in China, that one is pointing up , then instantly you will know the other one will be pointing down, although you can never communicate that together as the speed of light. Causality is still preserved, its not really an instant thing , as transfering information that is violating general relativity , just the information was there from the start and when you brought the stuff apart , one in China and one here, then you measure. Its not like you're transfering the information to this one. Quantum states always knew that it was a superposition and the fact you observed one here , means it wil lbe the othe rone there. Recently used in a particle experiment to test CPT theorum. In the SM you get fermions and bozons that are Ws and Zs biut from what I've read, the Ws and Zs get their mass because they so-called eat Goldstein bozons. In other words they have to get longitudinal polarization and that seems quite a different mechanism than your way. But the fermions, do they have a completely different way to get their mass.? I wouldn't say it was completely different, it is similar. Its all related withthe Higgs mechanism . I mentioned the fermions getting their mass by interacting wiht the HF , I didn't mention that some of the bozons get their mass through also interaction with the HF . I did mention that they got their mass because the symetry was broken and that's also why the fermions get their mass. Technically they are different. The fermions interact with the HF The upper part of the plot is symetry unbroken phase and lower is the symetry broken phase. Before the symetry is broken , the weak bozons are called W1,W2 , W3 and there is a guy called a B which is not quite a photon . Only after the symetry is broken do you separate the photon from the Z , the W+ and the W-. Similarly befroe the symetry is bromken you have the lefthand guy , which is completely different particle to the righthanded guy. Transformation properties. When you write the interaction, of lefthanded quarks with the right handed quarks, LHQ are 2D objects under SU2 and I'm trying to make an invariant, invarint with a guy with mass which is not a 2D object. Its like trying ot make a scalar product between a vector and a scalar. Its not going to work, I need another vector. I need anothe r2D object, the Higgs also a 2D object , a top part and a bottom part, not top and bottom in the quark sense. There is an upquark and a down quark in a left hand object which is also a doublet , so I associated a kind of scalar product, one with the other. Maybe the up goes with hte H+ and the D goes with the H0 and then I can associate that with D-righthanded. So I would have something like the U and the D , then the righthanded D here. Then when it breaks and gets a vacuum expectation to the lower bit , which is not charged electrically (the upper part is + charged electrically) so I now have an interaction that loks like the up part is not contracting with anything , because it would have to go through the H+. The bottom part goes through the H0, now a number rather than a dynamical thing. It multiplies the D-righthanded. It now looks like the scalar product of 2 scalars LHD and a RHD, jus tmultiplied and multiplied by a number, that number becomes the mass. With the weak bozons , it is trickier . There is 3 of them kind of 3D and I need to make an invariant combination with these guys. You can make an invariance and when they drop to here on the plot, you can separate stuff into W+ W- . electrivally neutral and something H0 or 0 squared perhaps. That also looks like a mass. These 4 mix and the way they mix is predicted by the SM , confirmed experimentally. You'll have a different strength of interaction between EM and the weak interaction , but its predicted what kind of ratio it will be. And it can be tested esperimentally. In terms of ? and bozons , when you break the symetry , this guy is a complex scalar so there is an H+ and an H0 , there is also a kind of antiparticle which is the H0' and the H- . Here you just have the H0 ,so where did the other 3 guys go , one is H+, one is H- its like A0 instead of H0. Its not actually a scalar . The extra polarization that a vector of a lorentz group , a vector like the photon which is massless only has 2 polarizations, transversal ones . A mssive one also has a longitudinal excitation. The photon o=scillation is constrained. The ones with mass can also oscillate longitudinally. They pick up this additional degrtee of freedom , missing bits from the HF. Q: The symetry being broken , that is something that is continuously happening or did it happen once at the beginning of the universe.? Historicallly it happened as the universe cooled down . We can restore it temporarily by going to high energy. Go above the "bump" in the wine bootle base , you can see the restored symetry. If you mimic the conditions of the universe before the symetry was broken , once again observe the restored symmetry. When the universe was really hot, its like the bottom of a beer glass. You can rotate the glass around and there is no difference. Its not at a minimum, which is a stable point. But not break the symetry because you can still rotate. But the domed bottom of a bottle, a W shape that you spin around , if you are in the middle point you can spin it around and it still looks the same. When the selected point goes to a bottom of the "W", it breaks symetry , rotating around it as no longer rotatable about that point , it breaks the SU2 but also breaks the U1. Has your SU3 fanmily has got any connection with super-symetry , particles like selectrons or is it completely different? Its separate. I could talk about supersymetry but it would take time. Can you explain gauge symetry ? All the synetries that I talked of , in the SM , not necessarily of the family symetries , are gauge symetries. Gauge symetry means it is valid at one point , but could be a different symetry at a different point. A local symetry , and in order to make things work properly you need to engage with the symetry of the gauge-bozon . Its also acting in EM where you have the electical field for example and can espress it in terms of a potential but as the field is defined in terms of a potential derivative in the middle , its like the electrical field is the gradient of the potential . You can pick an EM potential that is different from that is over there and I can still get the same electric field. Its only the electric field that is physical , so both choices would be valid , its like I chose a different gauge. You can choose a convenient gauge or remain gauge-agnostic . If you choose a different gauge , you have to be careful , as at a certain stage you need to not overcount your gauge choice. If you fix your gauge , you can look at the interactions and forget that you've already fixed the gauge. Q: What is the property that is conserved In hypercharge it would be the hyperchargr. In EM the property would be the electric charge. In these symetries that are higher dimensional , objects in SU2 are usually at least 2D, in SU3 are at least 3D , the components of this object and that object are related , you cannot break it. So what would be conserved in a weak interaction for example, is that if I saw an electron , I know that the neutrino involved in the interaction would have to be an electron-neutrino. In SU3 , what is conserved , is basically colour to some extent. You have to make a combination that is colourless and you're never able to separate them out. Did Cerne recently measur esome mass associated with the Higgs Bozon, how did it gain its own mass? As everything else, by interaction. In this case interacting with a Higgs bozon, or with a HF. What is making this guy go down and then up, there is a negative term in a quadratic so it starts going down and also a positive term which is quartic , -H^2 + H^4 and at large values H^4 flips upside down. Because there is an H^4 term that also indicates that the higgs interacts with itself. It interacts like 2 higgs with another 2 Higgs and if you look at it after you give it a vev? you can pick 2 physical Higgs fields . So out of the 4 , the first 2 are the physical particle observed but the other 2 instead of physical particles, take the number that is here. So with H H H H one is the H0 field I observe, second one is also the observed field and the third and fourth is just a number. When I look at it again it looks like there is a quadratic term rather than a quartic. The H^2 ones are precisely the mass terms ,so the mass is going to be a combination of the quadratic negative thing here, with the quartic thing when I replace 2 of the physical fields with the number it gets with the expectation value. What your getting is a sort of combination of its natural mass and the mass it gets from having an expectation value from interacting with itself. It also relates now the 2 different numbers , predictive in the SM because there is only 1 H, the quadratic and the quartic term , 2 numbers, the negative in front of quadratic one and positive number in front of the quartic term. You can get some information from the bozons. As soon as you completely measure the mass you can figure out the number in front of the H^4. For the hypochandriacs amongst us , that one neutrino interaction in one body in one lifetime, is that one ruptured cell , or what? No it will produce , not wanting to panic you. Anyone who likes bananas , they are relatively radioactive from the isotope of potassium commonly occuring in them. Also in a long distance airplane flight, it goes to high altitude to save fuel , so less atmosphere above you and you ar emuch more exposed to cosmic rays. From reactions in the universe , muons, protons impinge on the atmosphere as showers. For example the arauras at the poles are examples of those particles being concentrated by the magnetic field at the poles. So if you're flying regularly like pilots you're exposed to higher radiation doses. So don't worry about any neutrinos unless you're near a supernova and you will die from othe r reasons. In Portugal there are lots of granite areas also. Neutrinos interact weakly , but if they are energetic then they start interacting more and more. The interaction is weak if the symetry is broken. If you were at a much higher energy scale where the symetry was restored it will interact more or less as the photons. In that case with lots of energetic neutrinos and lots of in-body interactions then you could die from that. Are they looking for super-symetric particles at the LHC? The point is that we had expected to have seen them already. We're still hoping. Many particle physicists are now of the opinion that if they were there then they should havde alreasdy appeared. Supersymetry was a popular model, before the LHC. It is symetry but not in the same sense as I talked about family symetry. Supersymetry is a generalisation of the kind of Lorentz group. Internal symetry, like gauge symetry , and symetries observable at the macroscopic level, associated with general relativity, bu tnot necessarily gravity. The lorentz symetries are responsible for conservatio n of energy , momentum and so on. The mathematical group they are associated with is the Lorentz group, its not an SU group but an SO group . SO3 muchly would be the group of all rotations in 3D. SO1,3 4 dimensions but 1 is slightly different to the othe r3. Its like in Special Relativity you have Minkoivsky Space instead of Euclidian Space, funny business withte speed of light , time being a bit different in the other 3 dimensions etc. THere is one generalisation of the Pointcare Group , is the combination of SO1,3 group non-Euclidean rotations in 4D space and translations. If you add translations to that group you hav ehte Poincare Group and there is only one generalisation from that , that gives self-consistent quantum field theory and the symetry you have to generalise it is supersymetry. A symetry that will relate the spin of integre objects with objects with fractional spin, fermions and bozons. Then if you want to preserve the symetry, then what we observe does not match it. Its a bit messy to break symetry in that theory , but it is a nice theory, because then from each bozon you have a fermion. For the fermions of the SM , loss/lots? of scalars , which you haven't seen so ?? is broken. For the bozons of the SM , related to the interactions and the Higgs , the scalar in the ??. You have fermions associated with it, which again you haven't seen , so the symetry is broken. But its very nice from the theoretical point of view because its mor esymetrical . Unfortunately you have to break symetry, so thats why it gets messy. It also gives us an explanation for some uncomfortable facts about the Higgs mechanism . Which is , if you have a fundamental scalar like the Higgs is, there is no reason why its mass should be so low. Sacalars are like sensitive to all the scales , that are at play. In fact the expected mass would be at least the mass associated with gravity. I mentioned gravity is really really weak for particles, thois would be for example, the carrier of gravity or the mass scale associeated with gravity in association with the mass scale of the weak interaction being weak because the symetry was broken at a certain mass scale. The mass scale of gravity is much heavier that anything I've been talking about. And in principle there is no theoretcial reason for the mass of a fundamental scalar to not be there. Now we've measured it , we know its not. It could be that we have a really large number subtracted with another really large number, and subtract to an incredible precision of more than 20 decimal places and then you get a cancellation that was just so. Its unlikely and supersymetry would ve a good reason for why its not, becaus ehte scalar is not really by itself but is associated with a fermion. The fermions don't suffer this problem of being sensitive to the mass scale. Not found them , so maybe nature is just cruel and keeps physicists wondering about this cancellation . Is that symetry from the Lorentz equations? No, that is in fact a different Lorentz. There is no t in this Lorenz. How do we know there is not a fourth generation? We have very precise experiments . There are 2 measurements that are relevant. One is in ? from the LHC , the LEP at Cerne. They were exploring the properties of the Z bozon , heavy about 90 GeV , lots of stuff lighter than it. One thing it decays to is a neutrino and an antineutrino and other stuff. Not necessary for the top quark and anti top quark ,because those are more heavy, heavier than the Z. If they were more like neutrinos then it would decay slightly faster because there is one more way it could decay . If neutrinos were lighter than kinematically allowed , a decay allowed by conservation of energy , there would be additional neutrinos allowed by that, then we'd have seen it. Also from the evolution of the universe, big bang theory and cosmology related to particle physics. The point is the universe started really hot and then cooled down. At a certain stage there is bariogenesis , when you are making protons and all the other common nuclei up to Iron. This procedure is very impressive, you can calcuate the abundances of the light elements and almost all of them are where they are consistent with SM and also 3 generations. Because the number of generations would be also floating around in the hot mess , then as it cools down ,the additional neutrinos would interact with recently formed new nuclei and associate them and mess up the abundances. So observe the abundance of Helium to Hydrogen is also a gauge of the number of generations , its pretty fixed to 3. If I remember something like 3 +/- 0.002 , never measure exactly 3 , always some error band. The lifetime of the Z is very precise but its only sensitive to stuff lighter thsn the Z. The result from bariogenesis would be sensitive to other stuff.

Monday , 09 November 2015, Sarah Green, archeology of human bones Title: *Dead Men Do Tell Tales * *(What we can learn from skeletal remains in archaeology)* Synopsis: Human skeletal remains are one of the few classes of evidence which give archaeologists direct contact with people who lived in the past. For this reason, human remains have the potential to tell us much about such vital topics as past lifestyles, diets, subsistence practices, and diseases. To understand the past we need, through the study of human physical remains, to appreciate how our ancestors managed to adapt to their living environment. In this talk I hope to share with you some of the fascination I have for the ways in which human skeletons do indeed ‘tell tales’ and how we can interpret these tales from an archaeological point of view. I believe that the more knowledge we gain about people of the past, the more it perpetuates their memory. People of the past wanted to be remembered, that's why they built monuments in the landscape. There’s no greater connection with the past than the physical remains of our ancestors. We’re constantly trying to understand who we are and where we came from, and archaeological human skeletons are the remains of who we once were. They tell us a story (no matter how big or small) on a very personal level that many people find they can relate to. 41 people, 1.5 hours Osteoarchaeology (oa) did not always have the prominence that it does nowadays, a few quotes. "Burials on historical sites are more trouble than they're worth. Unless the circumstances are very special, I advice quickly covering them over and forget you ever saw them" That was in the Historical Archaeology Journal, 1975. " human bones don't provide that much information , after all we know they're Indians" An archaeologist telling a reporter in Colorado, 1989 Thankfully we've moved on a bit from then. Skeletal remains can help us understand the physcal characteristics of people in the past. Evidence for diseases , some diseases of the past are not totally in the past. Evidence of human fossil-forms, evolution of early hominids. Firstly how early studies hindered oa. John Lightfoot the VC of Cambridge and James Usher the Anglican Archbishop. They were looking for the date of creation. Reading the bible complelely litterally , worked back through the generations to come up with the exacty date of creation - Sunday October 23, 4004BC, just before nightfall. They also calculated that Noah's flood would have been 2348BC. That meant that in those times anything else that happened had to be fitted into that period, after Noah's flood as it destroyed everything. Wm Buckland fossil hunting in Dorset. This occassion he was in a Welsh Cave, Pavaland. He found human bones stained with red ochre and some fashioned goods, made from bone antler and ivory, also a large mammoth skull in there. In 1823 , pre Darwin , because of his religious conviction he could not date it earlier than the flood. So he came up with it being a female roman . He said it was female because the body was stained with red, therefore it must be a prostitute. In 1912 someone reexamined it and realised it was male . The skeleton is still known as the Red Lady of Pavaland and he is in the Oxford Natural History Museum. Modern dating as but it back to 33,000 ybce. Those bones come from the oldest ceremonial burial in England, possibly Europe. Why do we have a skeleton. There are 3 main functions. Support, locomotion the biones are leavers that the tissues and muscles are attached, and for protection of the sensitive internal organs such as the skull protecting the brain. Various types of bones. long bones , legs and arms and also metacarpals, metatarsals, bones longer than they are wider. Then short bones, tend to be of the wrist and ankle. Flat bones of the skull and the sternum, then irregular bones . How many bones in an adult skeleton . 212?, half of those are in your hands and feet. 106 bones in your hands and feet. 22 bones in the skull. We tend to think of the skull as one object, but when you're born , the skull bones are not fused together. So what tales do dead men tell us. The age and sex structure of the population, the physical size and appearance, the strtesses of daily life and diseases in the past. This is telling us about populations, but we have to remember this is only a sample of the population. For example the men in Sweden are buried i n a different part of the cemetary. To determine whether our skeleton in life was male or female. The pelvis in the female is adapted for childbirth. The psiatic notch , the female is wider. The subpubic angle in the female is > 90 degrees and the male is less than 90. That is for someone displaying very male or very female characteristics. There are other landmarks on the pelvis that we look for to help build up the oicture. The second area , to determine m/f is the skull. The male skull tends to be bigger than the female. For the female a flat forhead, male is more sloping and larger brow ridge. Also the mastoid process, just behind the ear, more pronounced in the male. The neuclal crest on the rear of the skull , more prominent in males. After gender , we need to look at age at death. A juvenile about 10 years old . An old person who lost all their teeth in life. If you loose teeth or they are removed , the jaw bone grows over the hole. An endented skeleton if its lost all its teeth. Zoom into the knee joint and compare adult and juvenile. The juvenile has a line , where part of the bone has not yet fused. When you are born , your bone is composed of cartilage, which as you grow, is ossified, turn into bone. Eventually the bones wil join uptogether and fuse. Therefore when younger you have more bones, a baby has about 300 bones. For a long bone you get growth in the ? or shaft and the ends the epithasees, they are growing also, to a pre-determined length, grow out , while you're maturing, then a layer of cartilage. On maturity that cartilage will ossify and the bone will completely fuse . As we grow , the bones fuse at different ages. For one pair of bones of the knee , they fuse between ages 16 and 23. A bit of difference between male and female. Other bone fusings occur at different age ranges. So if you have a complete or near complete skeleton you can piece together the age at death. That works well for age of children up to age 20. When the bones have stopped growing it becomes more difficult to determine age. You can use tooth wear for the middleages, before the era of sugar and refined flour. Previously the coarse grain ground down our mollars, and the dentine beginning to show. They are quite wide ranges of ages that we look at, 18 to 30 , 30 to 40 , age 45 and over its all over as far as your skelton. In the 1980s there was an excavation of the crypt at Spittalfields Church. Between 1729 and 1823 , piled up the coffins, and jumbled up. In 1984, the coffins and skeltons were replaced. Because a lot were in coffins, they had name plates so we knew what gendrr and age they were at death. So a good test for the accuracy of our sexing and dating is . 98% of the remains of adults that were looked at, were correctly sexed, using the skulls and pelvis. 58% were estimated to be younger than they were. Paleo-pathology, the study of old disease. We have to remember an individual may show signs of numerous diseases and not all diseases show signs on the skelton. So we may not be able to determine what they dies of but may be able to tell what they suffered from in life. The bones we see are dry. In life they have tissues attached and enclose blood vessels, bone reacts to the life of the person. 30% is organic material that degrades after death and 70% is inorganic . The core of , especially long bones , is a honeycomb structure. Bone is tissiue, its constantly turning over. As old tissue dies, new tissue is growing, bone remodelling. Several types of cell that helps in the breakdown and regeneration of bone. Osteoplasts that look like pacmen, they break down the bone , to make room for new tissue. This can be normal regeneration process, or the result of disease or a break of the bone. Then we have osteoblasts that lay down new bone. Q: Does this happen internal or on the bone surface? All over inside and surface. In the middle ,between osteoblasts and osteoplasts are the ostecytes, that maintain the bone . Diseases in past populations , Leprosy, Tuberculosis and Syphylis and what signs they leave on the skeleton. Leprosy (Hanson's disease) a condition caused by microbacterium Lepra. The face becomes blotchy and lumpy , nose has foul discharge and eventually the bridge of the nose will collapse. Because there are bone changes, we can see this in excavated skeletons. Lepers with damage to their hand and feet is not necessarily due to bthe bacteria. The bacteria cause your extremeties to loose sensation , so walking around and tread on something, then infection , you may not notice you've trodden on something. Hands to a lesser extent. The earliest skeleton with leprosy was buried about 4000 years ago in India. Absent nose, bone growth , and blood bourne infection and bone reaction to it in the tibia. There are Sanskrit texts composed about 1550BC . The earliest in Europe is 7th C Bolognia, we have his metatarsals , lessions and thinning typical of leprosy, pencil shaped. On his thumb part of the bone is falling away after an infection. In Britain , some skeletons in Glocester showing leprosy from Roman time, and Poundbury in Dorset. Today we think of leprosy as a tropical disease, because most caseds are found in less developed areas. That was not always the case, about 1200AD there was about 19,000 leper hospitals over Europe, 300 in England. Run by monks attached to monastries, known as Lazar Houses. From a reference in Leviticus to leprosy but it might have been a broad range of skin infections. Then Lazarus in the New Yestament. Many of the Lazar Hoses were dedicated to Mary Magdalan. Leprosy seen as unclean and so association with prostitution. Pope Alexander decreed that lepers should have their own separate churches. It was strongly encouraged to give arms to lepers and leper hospitals. It was felt that lepers were undergoing pergatory on earth. You were then helping yourself for your turn in pergatory. St Botolph's church in Bramber, W Sussex, in the chancel is a small window known as a leper squint. Where those thought to bed unclean and so not allowed into the church could congregate outside when communion was taking place. Not necessarily being able to peer in but able to hear what was going on, particularly the bell during communion. Most services in Latin then so not likely to understand proceedings , bu tthe bell indicated the most holy part of the service. Its a small village now but there used to be a leper hospital there. Known as Mary Magdallan and that area of Bramber is now known as the Maudlin area, in derivation. Southampton also had a leper hospital, , Le Maudlin also derivation of Mary, Winchester Road now crosses its site. Chichester had 6 hospitals , 2 in vhte roman walls , 4 dedicated as leper hospitals. Winchester had one, known as Mary Magdallan, excavated by Time Team. 54 skeltons were excavated. A page listing just the leper hospitals in Hampshire. So it affects nasal-palatine area, resorbtion of the digits and peristitis a blood-borne infection, affecting lower leg bones. Leprosy was dominant here to the 14C but in some of the Scottish islands to 17C. In mainland Brittain , leprosy becomes taken over by Tuberculosis/TB. The increase in TB is thought to be due due to increase in urbanisation . With people living close together , leprosy sort of mutates to TB. TB is due to bacterium tuberculosis and also microbacterium bovis , the bovine form of TB. With people living together with cattle we get the cross over, spread between animals and humans. Robert Coch first isolated the disease, awarded the Nobel Prize. Its been known about for thousands of years, Hypocrates 60BC wrote abouut it. Also been known as consumption and the white plague. Even today 1/3 of the world has been exposed or been infected by the organism. Some people have it, and it lies dormant within them. There has been a resurgence of it since HIV, HIV affects the immune system along with TB. In Kentucky more people were killed by TB during WW2 than killed in action. The type of TBthat manifests itself on the skeleton is spinal TB or Pot's Disease. It affects the vertebra, causes the vertebral bodies to collapse. The infection goes into the discs between the vertebra , the discs collapse then the spine collapses, bending of the spine. A statuette from about 4,000 bc , possibly showing signs of TB. A mummified priest of Amun from 21st dynasty that we've found traces of TB in the spine. Medieval treatment for spinal TB , lie on a plank and roll his back to straighten. There is also scrophola , affects the lymph nodes in the glands . Also known as the King's Evil , because it was felt that if the king came round , touched your kneck wit a gold coin , you'd be cured. He also gave you the gold coin , which probably helped. as well. Toponimal? diseases, non venerial syphilis, venerial syphilis and pinta. Syphilis does nasty things to your head. Pitting on the skull and also on the lower legs a blood-bourne disease. The phrase a nightime with venus a lifetime with mercury, old treatment was with mercury. Controversy about when syphilus first appeared in England, was it brought back with Colombus 1493 . Some skeletons potentially show that syphilus was in England prior to Columbus. Skeletons radio-carbon dated 1445 to 1520, Ipswich Black Friars cemetary , female aged >50, with head lesions and lower legs. Wth carbon dating, the nearer to the present day, the error band widens and also affected by nuclear weapon testing. Gloucester Black Friars cemetary, 18 to 25 , male, signs of syphilus on the skull radioC dated to range 1236 to 1549 so again not conclusive. From Essex , female , 25 to 50,radioC to 1295 to 1445 which is pre-Columbian. So if the dating can hold and it is genuine sign of syphilus on the skeleton , then potentially a pre-columbian case. We don't have all the skull. There is about 55 cases where it is suggested may be pre-Columbian contact. Someone has analysed all those skeletons and have stated that there is not full definitive signs of syphilus or dating is problematic. The jury is still out on this, as science progresses we may find more conclusive analysis. Q: What about skeletons from the New World, as it was supposed to come from there, signs of Pre-Columbian infection? The problem is did contact post Columbus mutate something else to creat it. We took lots of things over there , and brought things back as well. A skelton from Costa Bel ? France from 4C AD, found in the pelvic cavity of a female , this foetus is potentially showing congenital syphilus, from mothe rto baby. Skull with lesions and lower leg pitting, not conclusive as to syphilus. Someone has suggested its what is known as lithopedian? where the baby dies in the mother , but not expelled from the body and is calcified, a stone-baby. Plus maybe some other disease affected it. A case-study, one of the earliest tpyes of operation, trepanning. There is pressure in the skull that you want to relieve, or release the demons in the skull or cure some disease. The skulls give clues to what happened to the people afterwards. Beaker period one 1800BC. The roundel taken out of the skull , may have used flints , sometimes a corkscrew type effect, sometimes a shell. Often that roundel would be kept as a lucky talisman. This person was not lucky because the bone has no healing. Like teeth removed from a jaw in life, the bone will heal over. If you live that skull cut will heal over. This person , it is as rough as when cut in antiquity. He did not survive and the roundel was buried with him. An Iron Age skull , a very rounded edge of the opening, so this person survived for some time and the skull healed. One from Peru, had 7 openings and they all healed. So transcontinental, evidence of trepanning. Q: How did they survive without getting an infection. ? We don't know as we don;t have evidence of how they treated it , probably herbal. I don't know what state of mind the person was afterwards. Suggeting opium as an anaesthetic. Shows that people were caring for their peers. A Case-study. The Mary Rose. When she sunk 19 July 1545, with almost full loss of life , we know exactly how those people died, drowned, caught by the anti-boarding netting. So we have a snapshot into Tudor life. We can see what those men, and all men on board, what their lifestyle was , general health and well-being, sealed in time. Evidence of their clothing because what fails to survive on land is preserved under the sea. A jerkin , shoes , woolen cloak a nit-comb complete with nits. Evidence of the weapons, the arrows, the longbows, leather spacers and woodstocks to fire the canon. Also evidence of cooking , the ovens, lots of pig bones from salted pig the bones that don't contain much marrow, keeps better on board ship. Hatch the dog found near the carpenters cabin , near complete skeleton , though to be a rat catcher. An example of mixed remains of some of the crew. When the ship went down a lot of bodies fell to one side. In the early stage of being on the sea bed, sea life would have come along and removed the hands and feet. From such muddle of bones the osteoarchaeologists managed to put together 92 fairly complete skeletons, matching the bones back togetjher. About 179 individuals in all , from a crew of about 415. We can see what nutrition was like . The diet was probably restriced in our terms, but better than the majority of agricultural workers. Dark on board ship, lack of sunlight so lack of vitamin D . Hence rickets , 2 types seen here in the crew. Rickets as a child , crawling baby the bones bow as they are not supported properly. Then in adult life the bones are still bowed. Then adult form of rickets , a sacrum , osteo-malascia?, from the base of the spinal column . Causes the bones to collapse in on themselves. We have evidence of trauma, perhaps ship board falls, breaking bones. An untreated but healed spiral fracture. Lifestyle adaptations. So a lot of lifting or pulling , the muscles will become thicker and those particular bones will thicken also. A femur with prominent muscle attachements. A modern equivalent could be a tennis player, a right handed player would have more promenent muscle attacehements on their right arm and trhe right bone thicker than on the left arm. If you wear a ring on your left hand and try it on the right hand it would not fit so well. Some peoplemeasur ethe falanges of skeletons to try and determine if they were left or right handed in life. Some activity markers on the spine. Young adults age 18 to 30, but the spines are what we'd expect with much older men. Sometimes the bones have started to fuse together. Schmalls ? nodes affecting the vertebral column wher e there isa lot of heavy lifting. Perhaps these spines belonged to the gun crew , pulling heavy guns in confined spaces will take its toll on your back. Metatarsal damage from turning your foot over, fifth metatarsal on the outside , there is a break but it has started to join back together. If he'd lived then that bone would have fused back together. Avulsion? fractures , where the patella pulls away from the tibia bone, when you land awkwardly. These injuries you would associate with mariners , running up and down the rigging. These foot and knee injuries found on the Mary Rose are not common in other mediaeval burial groups. On the scapula , shoulder bone, on the acromium , would normally fuse to itself. For some people it remains separate throughout life. In modern population about 3% will have that non fusing. On the Mary Rose, 26 out of 207 of the scapula showed this osicromialis? 12.5%. Why would that be. Men under Henry VIII were required to draw the longbow from an early age. Your shoulder is constantly being pulled back as you lay into the bow. So the bone trying to fuse may not be able to do so. So possibly these are archers. Investigating the posistion of the archery artefacts, the longbows , the spacers , wristgaurds, were they found in same areas as the men with osiacromiali . Sometimes it was , sometimes not, it does occur naturally in 3% anyway. A man 1.76m high , with bilateral osicromiali , both shoulder blades, prominent muscle attachements and also a twisted spine, perhaps from pulling bows. Facial reconstruction has been done, another man age 18 to 21 1.82m , he was found with associated archery eqipment. Then someione without osiacromiali , also a twisted spine , but he was found with a long bow and a wrist guard. Some of the skeletons still had the gaurds on their arm. Someone with severe damage to his right elbow, arthritis but he was found associated with archery equipment. We had 415 men listed in the Anthony Roll that lists the crew. 185 soldiers, 215 mariners , 30 gunners but no archers. So where are the archers. Some of the wrist guards had the Tudor rose or the Fleur de Lys. Perhaps they were the King's personal retinue, specialist archers brought on board. One of the wrist guards was with the right arm , so a left handed archer. Particularly in Tudor times left handed men were regarded with superstition. Mary Rose research like this is still ongoing. So with a 206 piece jigsaw of jumbled bones, how do you begin to unravel with multiple skeltons? Comingled remains. You first separate off where there is one bone per body like skulls. You look for lefts and rights. You put the right humeruses together and all the left ones together. I've been working on remains in Crete, over 400 skeletons found Minoan Bronze Age, 3000BC. These were put in as an ostuary, so buried and then a few years later they were moved to another place, by which time some bones are missing. They were found after dynamiting for a road. Those will be next to impossible to separate out as they have been so comingled. So you try and learn what you cancfrom the life of those people, so compare all the humerus, all the skulls, toe bones. with the Mary Rose some will have been trapped in the ship , trapped in one place so you have more chance of separating out. Bones do fit in together so you can match up pelvis to femurs, say. It depends how many you have and how much they're jumbled. Much is made of archers , whether the Amesbury archer or Mary Rose ones , about muscle attachements. But looking at that medical student skeleton there earlier on, I couldn't see anything in the way of micro-grooves or anything , what are muscle attachements on the bone.? This is a basic skelton , not designed to be anatomically correct. If this was a tennis player , then certain areas of the bone, landmark areas , where the mucles attach, you'd find a thickening or roughening on the surface, as a ridging on the bone. Do bones have holes for blood vessels to go into? Yes they are known as formena? which just means small holes. You can use those phoromena to orient youself on the bone, especially if only fragments of bone, like I tend to find as I specialize in animal bone. Only a few per bone. Where the blood vessels go into the marrow part of the bone. People used to be shorter and gradually they've got taller, isd that right? For certain populations that is the case. There are also populations that were taller, the Minoans they're av height was 5 foot 2, so definitely shorter than us. But there are examples from Africa where they were very tsll. The body will adapt to climates and nutrition, in Africa can be taller. In colder climates , Inuit say , they tend to be smaller. In Tudor times were they shorter? Back to the Mary Rose, an archer at 5 ft 11, he was the tallest, 5ft 2 , 5ft 5 was more the average. The osteoclasts/blasts? that break down bone , are they responsible for the spongey structure or are they smaller than that? They are microscopic , but they will cluster around where sites need to be attended to. The spongey structure of bone is part of the overall design? The Haversian ? Canal, the microstructure of bone, is concentric circles with the blood vessels going through them. Then the osteoblasts and osteoclasts cluster around those and do their jobs. All those years of watching Time Team, they never explained the commonly observed aspect that sandy soils were the worst for bone preservation, is that the case and if so why? Bone is one of the most hard wearing of archeological remains that we have . It is affected by the soil it is buried in . A chalk soil would be quite bad for bone. Its all to do with acidity and alkalinity, in association with hte amount of water passing through. It survives better in some soils. If the bone is left exposed fore a while , before being covered has an effect. Plus many more reasons, a whole science called Tophonomy? the lore? of burial. Teeth ar ethe most hard wearing, the enamel is hard to break down. You could find just a set of teeth in a burial site and all trace of the other bones has gone. I heard they can isolate isotopes from bones and tell what the person's diet was.? Isotope analysis , essentially your teeth will be laid down from when you're born to adult. Your teeth will tell where you were born using Strontium isotopes , from the water taken in as a child and that will stay with you for your whole life. Your bones will give indications of the last 6 years or so of life. Perhaps tell where you lived and also what you ate, based on carbon and nitrogen isotope analysis and to do with whether you ate marine , meat or vegetarian food mostly. With the oseoclasts changing the composition of the bone, this only applies to the latest 6 years of life. You can do this with quite a small sample of bone, drill into a long bone and remove a sample. Does Strontium vary that much from area to area? Even within a map of England you will have various bands of Strontium levels . A lot of work these days on population and migration studies . There wa sa skeleton found in the north of England that they thought had negroid features on the skull and the strontium analysis he'd come from north Africa. That analysis is infallible? As much as any science is. It does change with advances but yes. Be careful what you eat. Carbon dating has quite wide bands of potential error, is that just hedging bets .? They do a confidence level assessment. 95% or 99% confidence. Are you asking the carbon dating , did this bone come from the paleolithic period , 100,000 years ago, or bronze age 3,000 years ago or trying to tie down to 1492. The wider range would give a 99% confidence , but a smaller range of dates might be less confidence. Bones contain collagen? Collagen is what you need to extract to do radio carbon dating . There is organic and inorganic material in bone. There is more chance of extracting the collagen from the large bones. I would not do the extraction, I'd send a sample off to a lab. What about cultures that practise cremation or partial cremation, doe sthat affect your studies by fire damage.? It depends on the heat of the fire. These days when we do cremation we granulate the bone at the end , so just dust. In earlier sicieties it depends how hot it gets . I personally don't study cremated remains , but you can determine male or female , diseases as long as the fire has not been too intense. Earlier cultures cremation did not have the intensity of fire that its possible to have these days. Speaking as a Yorkshireman , is it definitely Richard III ? Its possible. Didn't they get DNA and compared with a living relative? I think we have to be careful with DNA testing. When radio carbon dating came out everyone thought we could then tell everything about dating but then we had to take into account nuclear testing . i think with DNA testing we also have to be careful that we don't think its the gold standard in telling us everything we need to know about people. I think its highly possible that it is Richard III. Do you think we are preserving enough stuff now that will allow future scientific tecniques , and we should have left it were they are? Sometimes there ar eparts that we don't excavate, because we know we can't conserve it, waterlogged remains in a well for example , we may not excavate . We want to be sure that when the time comes it will be there for those in the future. I never realised that archaeologists did that? I've been on a site with such a well , left intact. We're better these days . If you go into some museums there are skeletons stuck togethe rwith glue , varnish over them, contaminated for any future analysis. We never know what direction science will go , we don't know what we should be keeping for better science in the future. A hundred years ago we would never have considered DNA. Pompeii wasn't there some houses falling down that they excavated ? In Ibitha? the roman villa at Bidna? the mosaics were covered with thatch buildings to preserve them, those buildings have now become listed buildings, so you cant remove them to preserve better the mosaics now Can we see trends of human evolution, from skeletons, in say the last 2000 year? Yes, thats a whole other talk. We look for bipedalism, walking upright. We look for brain size, structure of the rib cage and internal organs, various ways the skeleton changes as evolution progresses. Evolutionary changes observable in more recent past, say since Neanderdals died out? Skeletons are always undergoing changes, evolution isn't finished. We can see minute changes, but changes nontheless. We have lots of vestigial parts of our bodies, like wisdom teeth, why do we still have such teeth, most people have them taken out because they're impacted, because our jaw shape has changed. We now have a different bite, instead of overbite we have underbite. I only had 2 anyway, a small example of changes going on.

Monday, 14 Dec 2015 Dr Joel Hirschi, of the National Oceanography Centre, Southampton. Ocean Currents and their impact on weather and climate I will illustrate how the ocean impacts our weather and climate with a main emphasis on the Atlantic ocean and the UK/Europe. The North Atlantic ocean has a profound effect on the climate of Europe and beyond. In addition to moderating seasonal winter and summer extreme temperatures in Europe (in the same way as the North Pacific moderates climate in Western North America) the Atlantic is characterised by a strong northward transport of heat in the order of 1 PW (10^15W) which is linked to the meridional overturning circulation (MOC). This northward heat transport helps to maintain temperatures in Western Europe which are higher than their counterparts at similar latitudes in Western North America. I will illustrate how we can simulate the ocean using computer models and how our ability to realistically simulate currents has improved in recent years. I will also discuss examples of weather events - such as the extremely cold December of 2010, which was the coldest December for more than 100 years in the UK - where we think the ocean played a central role. Recent results also suggest that anomalies in the ocean circulation (in particular for the MOC) can lead the development of anomalous sea surface temperatures (SSTs) by several months to several years. This suggests that the ocean circulation can be used as a predictor for SSTs and of the weather conditions associated with these SST anomalies. 33 people, 1.5 hours I'm a physicist at base and want to understand how ocean currents work and how they influence our climate. I have colleagues who develop devices to go out to sea and tyake measurements. I'm on the theorectical end using computer models to build up a global framework of ocean currents and understand their basic physics. Lots of other colleagues doing various bits and pieces, then sit together to collaborate and answer questions that emerge. Our climate is structured basically by the sun. The Earth orbitting the Sun , with its energy that sets the atmosphere and oceans into motion. At latitudes around the equator we see more enegy than higher latitudes. Atmosphere and ocans jointly try to transport energy from the low latitudes to the high latitudes to remove the imbalance. An ongoing movement of atmosphere and oceans, constantly carrying heat from the tropics to high lattitudes. This process does not happen in a smooth way. The insolation, incoming energy from the Sun , a ta latitude similar to the UK. Year after year its almost a perfect sine curvre. There is a bit of variability in the Sun, there are cycles, but the main signal is the same year to year. This is not true as for the weather we get, not just day to day but the seasons vary year to year . We have a forcing from the Sun that is near enough constant from year to year but a ? response in the atmosphere , that generates our weather, it varies a lot from year to year. The wiggles ar edue to the atmosphere and ocean coming together. To get a broad view on the impact of the oceans on our climate. The temperature range , during a year, from coldest to warmest month . So for us in the Uk it is July minus January, the warmest and coldest months. Just considering the north hemisphere, there are huge differences , N America or Eurasia or Siberia , although all at 50 deg N, all very different. But very small differences over the oceans. Summer and winter are not that different , in the tropics, large differences at high latitudes. If you are away from the oceans , west toeast. So Asia has high diffence reaching almost to the Pacific coast, compared to western Europe, and much smaller range. Same with N America. Depending on how the land mass sits with respect to the ocean has a large impact on how our seasons are shaped. The temperature anomalies with respect to different latitudes. On the globe, where temperatures ar ewarmer or colder if you stayed at the same latitude. So 51 deg N, southern England it is quite a bit warmer than you'd expect. Move over to Labrador, Canada , is colder and the west coast of Canada is a bit warmer but not as much as in the UK. This shows the North Atlantic is quite a bit warmer than any othe rplace of the northern hemisphere at the same latitude. Even up to Norway, 5 to 10 degrees warmer , average of all the seasons taken together. So why this warm patch in the middle of the Atlantic. The majority is due to a current we call the Meridional Overturning Circulation, MOC. It consists of a surface part, a subsurface part, a global current, all the basins are involved. Like a conveyor belt of warm waters , constantly bringing warm waters from low latitude , all the way to the North Atlantic , where it looses its heat to the atmosphere. By losing its heat, it gains density as colder water is denser, so it sinks to great depths in the ocean . It returns south , to the south Atlantic, where it upwells and joins the surface branch and the cycle starts anew. For 10 years we've been closely observing this current. It transports a vast amount of heat, 1 petaWatt, 1 and 15 zeros. Equivalent to about 1 million average size nuclear power stations. Enough to light a 100W light bulb on every square metre over Europe from Sicily to the Eurals. That on its own is not sufficient, you have to consider the atmosphere also. That heat only matters to us if its carried our way. The mean high and low pressure systems typically found over the north Atlantic. The Icelandic Low and the Azores High. They do drive an airflow , predominately west to east . So for us its carrying air coming from the Atlantic , going into Europe. Bringing moisture and temperatures warmer than you would otherwise expect. To some extent there is the same thing over North America , but there is not so much current and not as much heat. Although the airflow is wrming North America , like Vancover , the same latitude as here , its not warmed as much as here. Two examples where the atlantic had big influence , on the air flowing inro Europe. December 2007 , much warmer December over much of Europe and Eurasia and also north America, very zonal winds . The corresponding pressure anomalies , lower than average pressure and higher than average pressure in the Atlantic areas and so stronger than average winds, bringing warm air onto the UK, somewhat like this December of 2015. The floods in the north of England, Carlisle is a similar pattern as then, so happens quite often. Complete opposite February 1956 , very cold, about 10 deg colder than average, over large parts of Europe. The corresponding anomalies in the atmosphere, much higher pressure than average over northern Europe, lower than average over the Med. That fed cold air from Eurasia interior and Siberia into Europe, maintaining very cold temperatures. One of the coldest months of the last century. Comparing latitudes and similar/disimilar. Global temperature field, location over south England and same latitude in Canada and look at the yearly cycling of temperatures from Jan to dec. Warmer in south England but more pronounced in winter time, Canada up to 20 deg colder and summers are similar in both places, only 1 or 2 deg difference. Its in the winter that these differences become very pronounced. Its often stated that the Gulf Stream (erroneous term) is responsible for this difference. The atmosphere circulation and what the ocean would do regardless of whether that Gulf Stream was there or not. If you make a fair comparison and move to the west coast of Canada on the same ltitude, Vancover area, it is colder in that area but not so different to southern England. It is that difference that is due to the ocean currents. It is airflow from the Atlantic that has a major impact on our weather. The ocean has a major impact o nthe position and variability of these airflows. So its not the ocean just sitting tyhere passively and passively giving off its heat to the atmosphere. There are interactions between the two. The predominent directions ,where the flow goes , is influenced by the ocean. The position of the jetstream , vigerous airflow that typically occurs between polar, north and south, air masses and the tropical, sub-tropical airmasses. Big differences in temperatur e that give rise to a vigerous current . Long haul flights across the Atlantic , one direction is often faster than the other . Flying USA to Europe is typically faster than the other way. The pilots exploit that west to east jetstream. The current in the Atlantic is strongly linked to where there are large temperature differences . Cold waters and warm waters next to easch other, where the Gulf Stream starts its flow to Europe, where there are steep gradients. The current aligns with that temperature feature. At places where there is that current, the temperature remains quite constant. In comparison nearer the USA the temperature varies from 35 to 55 degrees and then comes back, almost a sine curve. Similar process goes on in the Pacific. The MOC current has been measured for quite some time. In 2004 instruments were deployed and we've been measuring that current continuously since then. It is done at 26 degrees north, between the latitude of the Canaries and Western Sahara and Miami. We measure the "red" and "blue" branches. We exploit existing systems. The transport in the Straits of Florida between Florida and the Bahamas. A large part of the "Gulf Stream" flows between htat strait. You can measure it by using submerged telecomunication cables. A voltage is induced in the cable and that voltage can be measured as a function of time. The voltage is proportional to the flow through that large channel . There is the Earth's magnetic field , with water moving through the field. Water contains ions , charged particles moving through a magnetic field experience a force , so positive particles are drivento one side of the channel , negative to the othe r side , so building up an electical field and a voltage that is picked up by the cable. A neat idea, didcovered by Faraday a long time ago . He thought he could measure the flow of the River Thames using that idea , unfortunately he failed because the thames is a very weak electriczl current in comparison. The thames is mainly fresh water so not enough ions to produce a measurable voltage. Even for huge stram like the Gulf Stream then gives only about 1Volt. That is enough to be measured in an accurate way. And correlate that to the actual transport. That has been done now since 1982, by colleagues in the USA and Miami. The second part of that curent is the part directly driven by the wind. At 26deg N , the wind blows predominately from E to W. What that does, counter-intuitively, transport in the ocean that is perpendicular to it. In the oceans large scale transport is always at right angles to the direction of the wind. This is true in N and S hemispheres. This current can be determined if we know the wind. The winds we know from ship observations and from satellites. We call it wind stress because it is the friction that the wind exerts at the ocean surface. Most of the work requires measuring the density difference of the water along the coast of Africa and along the coast of the Bahamas. We have to measure that as a function of time , the fullv depth of the water column. If you know the densities between the 2 coasts you can compute a transport across the whole basin. There is a geostropic ttransport , essentially a pressure difference that is between the eastern and western coasts of the Atlantic. Again the transport is perpendicular to the gradient. Gradient E to W, then the transport will be N - S. That density is also a function of depth. Then combine the transports , from the cable, the wind stress one called Ekman after a Swedish physicist who discovered that principle in 1905. Add them together and make a simple assumption that there is no net mass transport , across that section. A+B+C+ a correction term =0. We have a structure that is homogeneous everywhere. Based on simple principles but requires a lot of work, instruments have to go in and out of the water i n a 1.5 year turnaround cycle. Moored instruments, monitoring all the water column depth, recover them, recover data, quality control it and then start to infer how strong that transport is. The overturning cieculation , which is the sum of the 3 components gives a curve that tells you how strong the flow is. The units are million m-cubed per second. So on average about 17 or 18 units transported northwards, carrying warm waters across 26N into the north Atlantic. All that water will have to sink somewhere and then return south , exiting the Atlantic . So we for the first time have a continuous time series of that transport. Previously this was only simulated in numeric models. I was involved in the theoretical part of that but without my colleagues going out to sea , deploying instruments,doing the observations, none of that would have happened. Further reading http://tinyurl.com/jfst6x4 "Potential for seasonal prediction of Atlantic sea surface temperatures using the RAPID array at 26 deg N" It transports a large amount of heat, it can modify the overall content of heat in the ocean. Lower latitudes receive heat and higher latitutes tend to emit heat to the atmosphere. The orbital circulation redistributes that. The surface branch, moving south to north, sinking at higher latitudes, flowing back down to the south Atlantic and completing the circle. Something similar but weaker happens in the southern hemisphere, water sinking around Antartica , going to very great depths, and flowing back . These currents don't come back to the surface until back into the southern ocan. For our area, what flows north has to come back south, otherwise the sea level would hump up. That equates to a net transport of heat. That heat transport is not constant with time. The representative arrows in the plot can change as a function of time. So we can have a weakening of the circulation at one latitude, but not necessarily at another latitude. It does not all have to change at the same time. You can have a heat convergence in one area leading to an increase in tempretature, or the reverse with a reduction of the transport, a divergence and getting colder. We think this was the situation associated with the 2 strong winters in 2009/2010 and Dec 2010. 01 Dec 2010, a lot of snow laying in Southampton. The snow is brought to us by the atmosphere bu tthe ocean hada role to play. We have to look both ways if we want to understand what is happening. The strengths of the overturning circulation for period 2008 to 2012. In particular 2009 and 2010 and we can see that in 2009 the circulation was quite a bit weaker than in earlier years. It went from about 17 million m3 per second on average in 2008 , dropped to a bit over 13 1 year later. In ocean terms that is a lot of energy that is missing in the north Atlantic for almost half a year. That corresponds to the situation we had in the UK . So less heat at 26 deg N, so a cold anomaly developed there , a negative anomaly. Move ahead in time and that anomaly in winter and reinforcement. In winter , water cools , it sinks and builds up a reservoir of cold watrer beneath the surface. The atmosphere enhanced this ocean change. By mising colder waters , deeper in the ocean , that cold anomaly got even bigger, corredsponding to the end of the winter 2009/2010. Moving tosummer 2010 , the circulation had almost recovered to nearly 17 units average. In summer the surface ocean warms up , becomes lighter and becomes unstable as well. Cold waters can survive as they are lower down , they don't just disappear. There ar ecurrents beneath the suface but they will take time to disperse that sort of anomaly. The anomaly persists, just sits there. The following winter in Dec 2010 that was ferrociously cold, producing cold waters, removed the barrier created by the warm waters of the summetime and essentially tapped into theat cold reservoir . Meaning the cold reservoir could reemerge to the surface observable in the temperatures of the ocean. A plot of anomalies of sea temperatures at the surface and subsurface of around 100m over this 2009-2010 period. Autumn 2010 and winter over to 2011. In the first winter, a pattern of anomalies , colder than average from US to Europe and at depth much the same pattern. Moving to autumn the pattern has changed a lot, the cold anomaly has all but gone , but at depth the ocean has retained memory of what hapened 6 months earlier. Then comes the next winter , the patterns reestablishes itself. The feature reappears at the surface and surface and depth look the same again. What was stored at depth reenhances the anomalies generated the winter before. The first time such a memory type feature has been observed, carrying over from one year to the next. Did that matter to the atmosphere. Does the atmosphere care about this pattern or just a passive reponse of the ocean. We applied the observed anomalies to an atmosphere model and did 50 simulations where we slightly changed the initial conditions , meaning the atmosphere can go in different directions. Its a very chaotic system , so doesn't take much to make it go in different directions. We wanted to see in those 50 runs , whether there wa sa systematic shift on average , compared to without having these anomalies in the North Atlantic that particular year. Summarising some of the results. The jetstream before and after applying a perterbation , the strength of the wind at 300mB height, about 9/10km altitude. There is an increase in velocities within the jetstream to the south and a decrease towhere its average position is. The predominent air flow in that simulated December has shifted to the south which is what we observed in Dec 2010 reality. The current shifting to the south, leads the way for cold air coming from the north or east, it opens up the gate for much colder air to invade Europe. A nice illustration of how the ocean can influence weather, what happened in 2010 had its origin more than 1 year earlier in 2009, when the cold anomaly started in the ocean. That was one very particular event, now we look more systematically at the SSTs and strength of the MOC. Ocean temps feed back directly yo the atmosphere. There is an intriguing feature , from the time series whether the temporal evolution in the ocean of the temperatures, look the same if the OC gets stronger , is there an increase in temperature anomaly. Can we something in the way of a time lag , the ocean preceeding what is happening to the temperatures. We have strong indications that this is indeed the case. A lag of between 2 and 5 months , there is a maximum correlation between the transport at 26 deg N and the developement of anomalously warm or cold water masses. This provides a potential predictability of up to 7 months, useful to get an edge on what a coming season could be, in the area of "barbecue summers" that never happened. We may be able to improve on such predictions by taking these findings into account. The areas where we see a link between the strength of the currents and the ocean temps is an area of the ocean that directly affects Europe. The area to the south is important in the developement of tropical hurricanes that impact the caribean and the USA. So again potential of advance useful knowledge about trends in huricane developement. So a stronger than average circulation , strong surface branch, strong at depth in the return, that tends to preceede cold in a specific region of the atlantic and warm in another specific region. If weaker then you get the opposite. What tools do we use. Set out to model the ocean and how has it improved. Changes in the Gulf Stream seem to imply a weakening trend, is there enough info to see if that is significant? The MOC has a decreasing trend, it is just about significant. Whether its something in the long term cycle, we don't know. There was a paper published last year that described this decreasing trend. One particular interest with that current, if we believe the model results and the projections for the future, the strength of this current is sensitive to global warming. So if the climate warms most modelling would predict a weakening of that current. If that current weakens, then that has an impact on the climate. That would mean that for the Atlantic , it could cool a bit, even in a generally warming world. A counter intuitive response , by the Atlantic but not impossible, but at the moment whether part of a short trend or something more decadal, I don't know. Is there any proxies that you can take the timescale farther back, I'm thinking from the natural world, deposistion of sealife on the sea bottom changing over seasons? Yes. There is a whole field , part of paleoresearch, trying to do that. You can look at the sea sediments, and proxies by species that are indicative of what the temperature and salinity of the water was in the past. Its not super-accurate but you can get some ideas and maybe go back a few hundreds of thousands of years, but not with the quality of date we have got. The temporal resolution maybe only 5000 year resolution. But you seem to be interested in minima and maxima which over perhaps hundreds of years, maybe pick up that? Yes , if there were big big changes, potentially we could pick that up. I wrote an article on this, but so far we've not got much along these lines, but perhaps one day. To go back 50 to 70 years you could use a model, applying what we believe to be representative atmospheric forcings on top of it and run it. We know the models are doing a reasonable job, not perfect but we can reproduce a lot of what we see in the curves of the last 10 years. So in theory if we get good agreement over those 10 years then we can take it back further in time, but not further back than 1950s. What sort of statistical methods do you use in your modelling, regression modelling? You've been looking at what the currents have been doing , how to process that for future predictions.? This would not be a statistical process. If you wanted to know about the future, you have to run the model into the future. Its a simulation so , not a statistical method but a full physical model, a coupled ocean-atmosphere model, climate model. You ascribe an assumed change in the level of CO2 for example , for the next 10, 20 or 100 years, then ensemble simulations , typically due to cost, less than 200 simulations. Even better if you use different models. Each model may have its own tweaks and features specific to it, that may bias a result in one way or another. To mitigate against that, its good to have a broad range so you can then estract common features from all these models. There are models we should discard but more often than not , since the IPCC report and use of 60 models. Some are attrocious and should never have gone into it but most are very good but they all have weaknesses somewhere. You take them all into account and you get a much more balanced picture. I've seen a research paper ( Petoukhov et al) on the jetstream and trying to explain how it can get locked into a specific pattern, they refereed to it as a quasi-resonant structure, with orographic forcings from the Rockies and the Himalayas and thermal forcings from the Pacific and Atlantic. The maths is beyond me these days, but it seems to make sense. And that could link in with what you're saying with a timelag within oceans and then supply that mythical connection between El Nino events in the Pacific and later events in our weather the next year, cross-coupling between Pacific and Atlantic which otherwise I cannot see how it could happen? The links between El Nino and events in Europe are not very strong. El Nino is not a good predictor for Europe, occassionally its right but more often not, its wrong. In terms of physics what you tend to have happen is the triggering of socalled wave-trains. Often triggered over the Pacific, these trains can travel in the atmosphere and after a couple of weeks they will start to merge into the jetstream, which then move towards Europe. It will have an impact but whether it is something systematic and how much stability there is in the system , we simply don't know yet. There is a specific number of wavenumbers the jetstream can adopt. You could see that as a coupling route between the Pacific and Europe rather than around the southern tip of South America? Absolutely yes. My focus is always over the Atlantic , The Pacific has a massive influence. At the moment there is a massive El Nino going on. It certainly has big impacts in many places but Europe is not one of them, where it is clearly seen. Could you give me some idea of how your deptment's work fits in relation to what is going on elsewhere in the world. Is this unique or are you 1 of 50 locations ? The NOC is one of 5 or 6 main ocean research centres in the world. One in France, 1 in Germany 2or 3 in USA that are comparable. These places are doing similar things, related but not exactly the same or there would be no point. Our emphasis is strongest on the north Atlantic, our doorstep. The MOC observations, only we are doing, collaborating with colleagues in Miami, a joint effort. In terms of impact on climate , climate-modelling, othe rcentres are doing that also, tens of such centres. In the UK we work a lot with the UK Met Office. So the models we are developing , the example I showed at the end of my talk, if everything goes to plan, it will be coupled to the Met Office weather forecasting system. So far the weather forecasts they produce and for the BBC, they don't use the active ocean . They just use the ocean as a passive boundary condition which is ok for a couple of days. You don't need a full interactive system for 2 days up to perhaps 7 days, but it would still be desirable to have it. What we do in terms of ocean developement , will feed into their system and forecasting. Is your ocean model purely mathematics or do you feedback quirks and foibles dicovered from instrumentation ? Every model has that. Some basic features we don't understand yet. We don't understand how properties are being mixed into this, so we use what is called parameterisation and none of it is entirely satisfactory, but the best we can do at this stage. Its not pure Napier-Stokes and nothing else? Thats what it starts with so-called primitive equations. Your talk would make an interesting part of a TV programme.? plus 2 who would watch it. Are you aware of a simplistic bathymetric model for UK coastline that you could run on a laptop and input very basic meteorological data, but not full station by station streams of met data, to get an idea of how surges develop around the coastline? I'm aware of the NOC NTSLF system that outputs lovely detailed predictive plots for UK ports but how it works is somewhat a mystery. Often I expect a surge somewhere and nothing develops or the opposite case, let alone the severity of any surge? Things happen in the North Sea that come around Dover or other times it doesn't.? Just a slight change in the angles and it is no longer the same feature. You should talk to my colleagues , the Proudman Lab, Liverpool . Their speciality is coastal oceanography. There are simple things you can do with simple models , a barotropic model, you don't need all the physics of 3D flow structure to get an estimate of a storm surge.


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