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
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
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
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
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
Q: Are the spots on these diagrams , where individual detectors
These are from the Japanese detector setyp. Like a cylinder
opened out . Sharp rings - muon event, fuzzy rings - an
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
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
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
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.
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?
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
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.
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
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
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
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
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
*Dead Men Do Tell Tales *
*(What we can learn from skeletal remains in archaeology)*
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
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
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
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
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
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
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.
Toponimal? diseases, non venerial syphilis, venerial syphilis
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
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
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
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%
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
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
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 ?
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
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
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
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
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
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
"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
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
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