The Low-Temperature Fairground

Well, There are not enough comments over here to keep this thing going, but I love my physics so much, I will do so. However, here's a point which piques the curiosity....

Superconductivity. Superfluidity.

What are they?

It happens at low temperatures. Low temperatures.

Very low temperatures.

Ok, without the details, here is what you see...

1. Substances conduct current for years without a power source.

2. Liquids appear emptier than empty space.

3. Liquids fall out of their own containers by themselves.

Helium is called a superfluid and has been well-studied. It seems to look like a combination of two different Heliums (maybe "Helia"??). Called Type 1 and Type 2. It exhibits superfluidity according to how near it is the Lambda point at 2.17 K. Only when it reaches 2.17 K does it become truly superfluid.

These are number 2 and 3 above. Technical term for No2 in "viscosity" - that is a word that means how hard it is to move a hand through the fluid. For instance, it is more difficult to move your hand through crude oil than through water, and more difficult to move your hand through water than any gas (gases and liquids are both called fluids in physics). As for the liquid Helium, is is easier to move anything through it than a gas, or even empty space. It feels like it is not there. It has zero viscosity.

No 3: A strange property of zero viscosity is that there is no resistance to the flow. The molecular movement inside the Helium is enough to drive it up the sides of any container ( from which it has no friction at all ), climb over the rim, and run down and drip from the lowest point.

As for metals, which is No 1 above, or more specifically, ceramics, the behave like there is nothing to stop the electricity flowing.

Ceramics are studied because their "lamba point" is much higher than 2.17 K. In fact, and this is not my field, but ceramics were close to having a lambda point at close to 79 K. This is significant because this is the boiling point of Nitrogen, and Nitrogen is much more common than Helium (Nitrogen is 78% of our atmosphere, Helium can only be gotten from rocks), and so is much, much cheaper.

However, for our coils, they have to copper, as here we have the conservation of energy again, as the advantage gained in the higher temperature superconductivity, is offset by the fact that ceramics are not good conductors.

Copper has lots of free electrons in it, Ceramics do not, and we can get a bigger non-resistive current if we are prepared to pay for the more expensive Helium.

Upshot is,

Copper: bigger current, lower temperature for switching superconductivity on, therefore more expensive Helium is needed.

The Ceramics: smaller current, but higher temperature for superconductivity switch on, therefore cheaper because maybe only Nitrogen needed.

The LHC needs copper to power the large magnets because the particles go so fast we need the magnets to be far more powerful because they have to turn the now heavier particles because of special relativity ( lol too many "because's )

Swings and roundabouts with a vengeance.

Why the LHC is so large

Here is a picture of how mass incerases with speed, along with the formula.....

m-zero is the normal mass without moving
m is the mass when it is moving at speed v
c is the speed of light = 299,792,458.00 meters per second
















....and here are the actual numbers.....


1. Rel Speed of Proton = 0.5000000000

Speed of Proton = 149,896,229.0000000000

SQRT(1 - (rel)**2) = 0.8660254038

gamma = 1.1547005384



2. Rel Speed of Proton = 0.9900000000

Speed of Proton = 296,794,533.42

SQRT(1 - (rel)**2) = 0.1410673598

gamma = 7.0888120501



3. Rel Speed of Proton = 0.9999000000

Speed of Proton = 299,762,478.7542

SQRT(1 - (rel)**2) = 0.0141417821

gamma = 70.7124459519



4. Rel Speed of Proton = 0.9999999900

Speed of Proton = 299,792,455.0020750000

SQRT(1 - (rel)**2) = 0.0001414214

gamma = 7,071.0678529787


The proton/anti-proton speed and the speed of light are in meters per second, the relative speed of the proton (rel = proton speed /light speed)is with respect to the speed of light eg 0.99 is 99%. SQRT(1 - (rel)**2) is the denominator in the equation in the diagram, and Gamma is the number of times the mass increases. It can be seen that even at half the speed of light, there is a definite measurable mass increase.

This mass increase is real, not an illusion, and at number 4, which is where the LHC will be next spring, we will have a proton weighing 7,071*936 units smashing into and anti-proton weighing 7,071*936 units, giving us a total of about 13 million units of pure energy. That's 13,000 GeV. When the heaviest particle ever created is compared to this at 90 GeV, an idea can be envisaged as to just how big an experiment this is. However, panic should not ensue, as the size of the units are irrelevant, you only need to notice how much more energy we have now than before, and it is an awful lot.

Suffice it to say, in order to bend the path of a proton that "weighs" 7,000 times more than normal, a bigger curve is needed, and I back-refer to the speed-boat/Ocean Oil Tanker example given earlier.

The next few months are going to be very exciting indeed.

Explanation of a Black Hole

There has been lots of bad press about the LHC concerning the possibility of producing "mini black holes that could swallow up the Earth".

Call this post the "anti-Newspaper" if you like.

Ok, so, Black Holes - what are they?

Keeping it simple, here we go.

Stars. Stars are simply large bundles of stuff (mainly hydrogen or protons) that are powered by nuclear reactions, the same kind as in the atom bomb. The reason they do not explode like an atom bomb is that there is so much stuff there, that gravity keeps it all in a ball and contains the millions of atom bombs going off every second.

It is a matter of balance between outward nuclear explosions, and the pressure inwards from the gravity.

That's for a normal star.

However they do not last forever, and there will come a point when there is no hydrogen left to explode. The star shrinks until gravity raises the inside temperature to be hot enough to explode the next element, Helium. When that is finished, it shrinks more, and burns even heavier elements.

Even this can't last forever, and there comes a point when it can no longer make any atom bombs at all.

It gives up at this point, and IMplodes, but the implosion goes right through the centre and what is seen is an EXplosion outwards. We call this a Nova.

What is left is a lot of stuff getting thrown out into space, leaving a small, dense stellar core the size of a small planet. This is called a white dwarf, and will cool into a red, then brown, then black dwarf. Gravity is stopped by outward atomic pressure.

That is for a normal star.

If the star is just a tad bigger to begin with, there is too much stuff in it to make a dwarf star, and the protons add electrons to themselves and all become neutrons, and the star shrinks to a smaller size. Then the IMplosion again, but what is left this time is a Neutron Star, exactly like an atomic nucleus, but the size of a city. Gravity is stopped by outward neutron pressure.

That is for a slightly larger than normal star.

If the star is bigger than about 2.3 times the size of our sun, nothing can stop the shrinking and gravity completely takes over.

To everyone outside, the star is crushed out of existence and becomes a Black Hole.

The size of these black holes depends on the original star, so at 2.3 times bigger than the sun, the black hole would be roughly the size of a football field.

Clearly, most stars are far bigger than the sun, which would mean that their black holes could be as big as a planet. Hovever, this would require a billion billion billion billion tonnes of mass to create.

All due to gravity.

The upshot is that a black hole is formed from compression, of any kind, but we only know about how gravity does it, However, it has been conjectured that during the Big Bang, pressures were so great that the possibility of black hole formation at that time is entirely feasible, bearing in mind that all the stuff of the universe was there at the time to create them.

The fears that the LHC can form mini-black holes are completely groundless because a) the pressure there is about a trillion trillion times less than needed, b) there is simply not enough stuff to make one even if the pressure was available, and c) in order to "swallow the earth" the created black hole would have to be at least as big as the earth.

Ever tried pushing a water melon through the eye of a needle?

Size IS Important

The Last Post may have been just that for some. Here is an even simpler explanation of what it is all about:

It's all down to E = mc2 (Multiply the speed of light by itself, multiply by the mass of a particle, and that is how much energy (in the form of electromagnetic waves, ie light) is available to carry on.

Matter plus anti-matter = energy.

However, If you have a proton (936 units) and touch it with an anti proton(936 units) all the energy you will get will be 2*936 = 1872 units.

So we speed them up a little, so that when they eventually touch, not only do we have 1872 units of energy, we also have the energy of their motion to add as well (kinetic energy) from the acceleration produced by the power invested in the magnets. Einstein helps again, as the faster they go the heavier they get, so much so that we can't deal with 2*936 anymore, but 2* ((10 or 20)*936) units of energy.

This is a lot of energy confined to a very small space. In fact, too, much, and "snaps" new particles into being using the E=mc2 in reverse this time. What comes out depends on conditions, but sometimes a completely new and really "heavy" particle is created.

As the machines get larger (they get larger because the particles get so heavy, we need more space to turn them, just as in real life, it is harder to turn an ocean tanker than a speedboat, so size IS important!), more energy is available at collision time.

So the essence of what we try to do is take known particles, speed them up, use E=mc2, smash them together and look at the bits. The bits are different when there is more energy available to create the heaviest ones.

The effect is rather bizarre if you think of it in everyday terms......Two unmanned sports cars at great speed collide head-on in a tunnel, and from one end emerges not bits of sports cars, but a slow and fully functional 18-wheeled articulated lorry, which very quickly explodes into several dozen kids tricycles of varying sizes, which scatter in all directions like frightened rabbits.

And who said travel wasn't fun?

The Big Bang at the LHC

Well, we are on our way.

Both beams of particles have been sent their wending ways, protons clockwise, anti-protons anti-clockwise (how appropriate!).

Today was just a fire-up test of the big machine, to prove that we could actually shine particles through the 1000+ steering magnets(dipoles) and the countless other focussing magnets (quadrupoles).

The proton stage this morning was actually done in half the time expected, with a corresponding timescale for the anti-protons.

We got them both up to 99.99% the speed of light. The goal, when all is working optimally, is 99.9999999 % the speed of light. That won't be until next March or April. That is also the time when the Black Hole Doosmdayers will emerge from the woodwork again

For myself, it was wonderful to see the actual beam on the screens in the control room of CMS. This project is older than I am !

Now that we know we can use it, tweaks will be made to refine the beam solid angle and it's centrality (which by today's results was pretty central anyway).

Here's the overview of the whole shebang. Protons one way, anti-protons the other way. This works because they are of opposite charge, but obey the same rule we learned in school : Fleming's Left Hand Rule.

The steering magnets do just that, they turn the beam in a circle (actually, the particles only describe arcs of circles whist under the influence of the magnets. Between the magnets, they run straight lines)

The reason why so much power is needed and why it is being shut down for Christmas is due to Einstein.

He said, the faster a particle goes, the heavier it gets. Newton said heavier things need bigger forces on them to change their trajectories (Newton's 1st Law), so we have to up the power of the magnets many times to cope with the increased mass.

The only way to do this and not blow a fuse is to have the magnets surrounded by superconducting coils. Superconductivity happens at very low temperatures, and what happens is so mysterious it could well be science fiction. An electrical current in a wire at those temperatures suffers no electrical resistance at all, and therefore no power loss.

This is what happens, our coils are superconducting, and once the current giving rise to the magnetic field is established, we can turn off the power. Of course, you don't get something for nothing, because now we have to provide power into maintaining the very cold temperature (colder than deep space).

That's how we steer the particles. To make the beam narrower and therefore more focussed, we use quadrupole magnets.

Recall that schoolboy magnets have two poles, north and south (they are the dipoles above). Quadrupoles have two norths and two south poles, and the magnetic field lines, unlike the dipoles which are straight, are curved, and they flatten the beam's solid angle into a thinner beam.

Dipoles steer, quadrupoles focus ( you can have octupoles and hexadecapoles with 8 and 16 poles respectively as well, but NOT decapoles (10 poles) or duodecapoles (12 poles))

So assuming the LHC is now fully operational in the Spring, what then? Well, we get the opposing beams to cross at 5 points around the ring, looking for where proton meets anti-proton, and using E = mc2, a maasive amount of energy is available to create new particles from the electromagnetic waves created. The energy available is so great, it had been labelled "The Big Bang" experiment.

And what is it we are looking for,exactly, the cry goes out?

Ever since physics began a very basic question has been asked. Exactly what determines each particles' mass (=weight). More specifically, why is a proton 936 units, a neutron 939 units, and an electron 0.511 of the same units? We know how to perform calculations with these numbers, but where do the actual numbers come FROM?

Nobody actually knows. However, Peter Higgs, a British Scientist proposed a gauge field (like an electromagnetic and gravity field) called the Higgs Field, which all particles move through and acquire mass from . All gauge fields have an associated carrier particle (electromagnetism has the photon, the strong force has the gluon, gravity has the graviton, and the weak force has the W and Z0, all of them Bosons (ie "spin" is integral))

The Higgs Boson would be the carrier of the Higgs field, and is so heavy that no accelerator has been powerful enough to produce one, until perhaps now.

THIS is the Holy Grail of Physics.

It is exciting because, if we DO find it (and we won't see it directly, it dies very quickly), we will know a lot more about physics, and if we DON'T find it , that means we do not quite understand what is happening yet, and a radical re-think will be in order.

Personally, I agree with Stephen Hawking, in that I am willing to bet it will not be found.

The Largest Telescope On Earth

This is it - September 10th. Switch on time for the "largest telescope" on the planet.

The LHC - Large hadron Collider - is a particle accelerator the like of which has never been seen before.

It is a circular tube 27km in circumference, so large that when you look down it, it appears straight.

Although particle physics is one level above me, I still understand most of what happens there.

The whole tube is a vacuum, and we will send protons around it at speeds never dreamed of before. In the other direction, we send antiprotons. Antiprotons have everything in them reversed,except mass. This means they are negatively charged, and because they are the same mass, the same magnets can be used to turn them.

The current in the magnetic coils are so large and energy draining they have to be cooled to 1.9 Deg K, that is -271.1 deg C to make the current superconducting. Superconductivity only happens at these cold temperatures and the upshot is that the electrical resistance of the wires disappears, so the power can be switched off.

At various points on the circuit, the two beams of particles cross and BANG.

Particle plus antiparticle means they both disappear into electromagnetic waves.

But these waves have so much energy, they don't last for long and SNAP, just like putting enough stretching energy into an elastic band will make it SNAP.

What comes out of the SNAP is a plethora of new particles and antiparticles, some of which we may not have seen yet.

What is worrying is that a gamut of people claim that creating a mini Big Bang (very mini compared to infinite energy) will produce strange things that will annihilate the Earth as well. Mini black holes are feared also (the same size of a proton), but they would not last long either.

September 10th will be a day long remembered, and I WILL BE THERE!!!!

Geneva expects.

Incidentally, the telescope analogy is valid because normal telecopes optically see small things (distant stars) and this "telescope" also "sees" small things with the huge ATLAS detector.

To those people worried about mini black holes the size of proton, this is just silly. Why? To create a black hole that small would still require the mass of a good-sized mountain, but the total mass of the particles in the tube is less than 1 gram.

Just what is a Quark anyway?

Apart from being a character in Deep Space Nine, a "quark" is a very fundamental building block of nature. The best way to explain what they are is to tell how they came about.

It was the 1960's, and the people at SLINAC (Stanford Linear Accelerator) and CERN (Centre pour European Recherche Nuclaire) thought they had finally got the big picture of atoms, nuclei and stuff. But the machines doing this smashing suddenly produced some particles never before seen. They behaved differently from the others and were labelled "strange". They disappeared very quickly into energy according to E = mc**2. None were present in nature.

Where did they fit in? The whole kaboodle could be explained by a whole new way of thinking: that protons and neutrons themselves were made up of something even smaller. Indeed, scattering experiments (firing the particles at themselves) seemed to indicate, by the pattern alone, that there was something else inside. Electrons had nothing inside them. Scattering experiments with them told us they acted like true "point" particles.

But just what was inside the protons and neutrons? They settled on the name "quark" and the proton and neutron had three each. One had two "up" quarks and a "down" quark, and the other, two "down" and an "up". "Up" and "down" being arbitrary names having nothing to do with the normal meaning, they might as well have called them "Laurel and Hardy", or even worse,"Bill and Ted".

But what were the strange particles? They reasoned that these must have another "flavor" of quark inside (nothing to do with taste!), which they called "strange". They predicted other particles to turn up with other combinations of up, down and strange, and sure enough, as energies (accelerator energies) went up, these predicted particles turned up. Then they reasoned, "Why stop at three quarks?" - there could be more. They tentatively predicted a fourth, and they called it "charm" (!), and this would produce around 33% more new particles. The lowest energy of these was called the "Charmonium", and yes, it was found, along with all the debris. It was essentially a quark-antiquark pair, or "bare" charm.

How many more were there, and where would it stop? For reasons not appropriate to be given here, they figured out there were no more than 6 in total, and they called the last two "top" and "bottom".

These quarks were getting heavier and heavier and were very hard to produce, but the last one to be detected was bare bottom, in the mid-80's.

It has to be borne in mind that it was never the quarks they saw, just big particles with quarks inside. The question arose - why can't we get a quark on it's own. It would be pretty easy to detect, as each had either 1/3 or 2/3 of the charge on the electron. However, not one had been seen,

The reason they gave was astonishing. Up till then the forces of nature were gravity, electromagnetism, the weak force (only affects electrons and neutrinos), and the "strong" force, which keeps a nucleus together against the static electromagnetic repulsion of the protons.

They reasoned that inside the protons, the strong force was the real strong force, much stronger than had previously been thought, and it was this that was "holding" in the quarks, as if they were tied to it with elastic bands. ( see previous posts for more info). Try to pull a quark out, and the elastic gets more stretched, as it gathers energy from the "pulling", until SNAP it breaks in the middle, not with a loud noise, but a new quark-antiquark pair, matter from energy (E = mc**2). The quark goes back into the old particle, and the new antiquark makes another new particle with the quark just pulled out!

There was another problem with this scenario. It goes back to an old rule developed by Wolfgang Pauli - no two particles can have the same description and be at the same place.

But in the proton there were two "up" quarks!! They figured. that the strong force, like electricity, had the equivalent of "charge", but whereas electricity has two, plus or minus, the strong force had three, and they called these three "color" charges (nothing to do with rainbows). So, in a proton, an "up " must have a different color charge to the other "up".

Because of this "color field" they named the theory Quantum ChromoDynamics.

Believe it or not, that was an introduction. I have left much out.

There IS truth out there!

The Angry Bits

This blog has now come Full Circle (as M Palin would put it) as I am now at a similar position as I was when I started this thing. I now work at CERN again. My permanent post is at Incheon University, but I am the (silent) manager of a project at CERN called the SSA.

The SSA has nothing to do with what CERN is about however.

CERN has been operational since the 1960's, the World's biggest scientific collaboration. It is perhaps the largest telescope in the world. We use bigger and bigger telescopes to see into space, which by virtue of being far away, details are small. Similarly, CERN represents a telescope devoted to "seeing" the very small, by virtue of them actually being small. We call the largest one the Large Hadron Collider, the LHC.

It bashes bits together and has already been under scrutiny in this blog (Three jets are better than two). It makes Hadrons.

A "Hadron" ( pronounced " Hey! - dron!") is a particle bigger than a proton or neutron. It is important to remember that everything we see around us is made up of only protons, neutrons and electrons. "Hadrons" are created by smashing protons together to get "angry" bits - bits that don't belong in the real world. We called them "strange particles" at first, because we didn't know what they were.

Now we know that all the evidence fits like a jigsaw puzzle into thinking that all hadrons (protons, neutrons, plus angry bits) are made up of three new particles called "quarks" (from the book "Finnegan's Wake"). These quarks build up all the particles, except the electrons which seem to act like they have nothing inside at all.

All these particles are very small and behave unlike normal particles, ie billiard balls. It was first realised they were different by Neils Bohr. This was then made into a formula by Prince Louis De Broglie, and then finally made rigorous by Schrodinger et al. as Quantum Mechanics.

The basic concepts behind quantum mechanics are thus: 1. All particles also behave like waves of something ( they give answers that can only be explained by considering them as a stream of waves. "Waves of what?" I hear you say - the answer to that only comes when you understand the math behind statistics and wave mechanics - trust me) 2. You cannot know with infinite accuracy all things at the same time. 3. A new thing called 'spin" has to be called for to explain some of the things we have seen (It is NOT real "spin" as in going round and round, but just another number (we ran out of names to call these things early on)) 4. Some of the effects we have seen can be explained by a particle description AND a wave description , depending on the way we look at it. 5. These things only happen when the particles in question are very small.

So what does CERN do? Simple, we bash the bits together to get new ones, well, we used to. We have just about gotten sick of all the new bits we get out of our collisions, and now we refine the bashing to get the bits back in more useful ways. It's a bit like a car crash, we now know what bits to expect out of the car crash, but now, we bash them together at different "angles" to see which parts survive best at those angles.

The upshot of which is that we are continuing to refine the theory (Quantum ChromoDynamics or QCD) so as to predict next which bit of the engine will come out of our crash and which way it will go.

If it comes out the right way, we predict stuff about the wing mirrors, etc, if not, and we get more angry bits, we go back and try again with a different version of the theory to explain what happened before the prediction went wrong.

As for the SSA, it is just a tool to make the data collection easier, nothing fancy.

The final upshot is that there are no more angry bits any more.