JoAnne Hewett has encouraged everyone to promote the ILC, the "Imaginary Linear Collider", as our phenomenological friends call it. It is a pleasure to follow her instructions. My comments are primarily addressed to the true American patriots who, I hope, are well represented among the readers. :-)
In 2007, a new collider called the LHC - the "Large Hadron Collider" - will start at CERN, Switzerland. I mean the old, socialist, and stagnating continent called Europe. It should discover some kind of Higgs - which is incidentally the "God Particle" - and perhaps some kind of supersymmetry - which is a symmetry relating SuperMen and SuperMenino - which would be really cool; for example, I would win a $1000 bet which will otherwise be lost.
The LHC is being built in the same 27-kilometer-long tunnel (in circumference) in which the lepton machine called LEP ("Lot of Extra Problems", later also called "Large Electron-Positron" collider) operated in 1999-2000 and nearly discovered the Higgs particle around 115 GeV, the current lower bound for its mass. By the way, CERN has previously found the W and Z bosons in 1983. All good physicists at that time already knew that the bosons would be there - and some of them had already been enjoying their Nobel prizes for the right theory predicting them since 1979.
You may notice that these colliders, i.e. particle accelerators (atom smashers) in which the particles collide to create a lot of new stuff (sometimes even interesting stuff), belong to two basic types:
- circular colliders in which the particles orbit many times and the centrifugal force - more precisely the synchrotron radiation that also occurs for nonzero acceleration of charged particles - is the main enemy of our attempts to accelerate it too much (LEP, LHC, Tevatron); very strong magnets are needed which is why the ambitious visionaries used to think about the superconducting magnets
- linear colliders in which the centrifugal force is absent, but the particles only fly once and therefore the linear tunnel must be very long (SLAC in California, ILC) and the electric fields must be strong
There is one more important classification - according to the particles they collide:
- hadron machines (protons and perhaps antiprotons): Tevatron in Fermilab, Illinois collides protons off antiprotons; LHC will collide two beams of protons
- lepton machines (electrons and positrons): LEP, SLAC, ILC; in principle, one could also collide heavier muons, but no such accelerator has been built and it could also emit too many unhealthy highly-energetic neutrinos from the unstable muons
The advantage of the hadron machines, such as the LHC in 2007, is that the heavy hadrons can carry a lot of energy if the velocity is the same, for example. Their disadvantage is that the hadrons contain a lot of glue and other chromodynamic dirt. Whatever you produce is therefore chromodynamically dirty and hard to identify and measure. The lepton machines, on the other hand, have some problems with getting really huge energies, but their collisions are very clean. An electron annihilates with the positron to a "pure energy" (imagine a virtual photon) which is subsequently used by mother Nature to produce virtually anything.
Neither technology is universally superior over the other; physicists tend to alternate the approaches as they raise the energy, in order to get complementary information.
The power of America
Currently the Tevatron in Fermilab, Illinois and SLAC in California are running in the U.S. In 2007, the European LHC may become the only active collider in the world; SLAC is almost sure to be shut down pretty soon. That could be as painful for America as Yuri Gagarin, especially if interesting new discoveries are made by the LHC.
This paragraph is really addressed to the true U.S. patriots: the U.S. could have been ahead by a lot because the SSC - the "Superconducting SuperCollider" - a 80-kilometer long circle - was being built by the nice, scientifically oriented Republicans. The collider was invented and proposed by Ronald Reagan in 1987 and continuing huge support was later led by the President Bush Sr., despite the fact that the communism was already gone, who claimed Texas as the new home for "his" SSC. (His son, George W. Bush, is also a pretty big shot in particle physics.) However, the evil anti-scientific, mostly democratic Democratic U.S. Congress later stopped the project after 2 billion dollars (about 20 percent) were already spent. Bill Clinton and Al Gore had different priorities in science, for example, the second guy wanted to pay hundreds of billions of dollars to cool the planet. ;-)
The Democrats will never tell you that the SSC was a project of Reagan and Bush Sr. and was killed once Clinton and Gore started. Most of the more recent frustration in particle physics may be attributed to the decisions in 1992 and 1993.
Whenever you will hear the bitter criticism against the string theorists or even supersymmetry phenomenologists that they are just too smart and 15 years ahead of the experiments, don't forget that it is not their fault. It is the Democrats' fault that experimental particle physics was slowed down for 15 years. ;-)
Even if the LHC is successful, the chromodynamic mud will prevent us from learning many details efficiently, or at least from measuring them accurately. This is why the ILC - which would become the "International Linear Collider" and the word "International" should really mean "Mostly American" - is needed. ILC would be a clean lepton machine where everything is nice and the desired products are produced without any garbage around.
For a couple of years, the particle physicists may be secretly afraid of bad luck. But be sure that if the LHC sees something really new, beyond the single Higgs boson, whatever it is, every other intelligent American will ask "How is it possible that Europe is ahead in these crucial discoveries?" Maybe you should already ask the question now...
Unless there is some inconsistency in mathematics, the LHC will have to discover something new that has not been yet. Something like the Higgs - the "God Particle" that transforms massless spirits into massive objects and particles. (Genesis: Let there be light in the form of the unbroken "U(1)" part of the "U(1) x SU(2)". And God realized that light was good and the Higgs mechanism was necessary.) While most physicists have already counted the Higgs as a "sure to be discovered" particle, this time we don't know what its mass will be.
The God Particle also gives mass to Himself (or the Jesus particle, if you wish) - by self-interactions - but we don't know how much He interacts with Himself although we know that His four-God coupling should be less than one or so. One of the additional magic tricks He uses to give Himself mass is to change Himself into a pair of an object and an antiobject for a while - which would typically lead to a huge mass of God, comparable to the mass of a dust particle (the so-called Planck scale). The puzzle why God is much lighter than the dust - which He apparently has to be if He is omnipotent and able to give mass to others - is called the hierarchy problem. The most popular solution still says that for each object and anti-object that are used for Him to get extra mass, there are new objects, the superpartners, for which the contribution is exactly opposite: that's called the supersymmetry. Also, I was cheating a bit: most of the mass of humans actually does not come directly from God and the humans are not as holy as I suggested; we are sinners and most of our mass comes from the chromodynamic mud. :-) Maybe, the non-physicists won't understand why this story is true, but others may assure them that it is true.
So the discovery of the Higgs will be a bit exciting anyway. But yes, if this is the only thing around, the ILC could be a bad investment. However, many of us expect more; much more.
An extra comment for all scientifically oriented billionaires who read this sentence: you may pay for the project and I will help you to negotiate that the collider will be named after you. If you pay for the whole thing, I will also help you to create new terminology of the superpartners for the case that they're seen. ;-) I don't expect that a new SLC - "Soros' Linear Collider" - will be built because the person is not sufficiently high-brow for such a project, but someone else could have different standards and more cultivated dreams.
And a special message for those string theorists who think that physics of colliders is their competitor and they don't want to support it. Forget it. We are one field with the phenomenologists. We clearly need progress in experimental particle physics because it helps us to choose the right questions and it creates excitement in the whole high-energy physics. Our colleague Quantoken has even figured out that it is really us for whom the new colliders are being built: the "super string theoretists". Roughly speaking, he believes that the purpose of the colliders is to increase the price of oil from $68 to $100 (the price dictated by Osama bin Laden).