[thedoc (OP)]

The Large Hadron Collider (LHC) at CERN in Switzerland is now back in operation. By smashing particles together at close to the speed of light, it promises to deliver dramatic new insights into the fundamental nature of the matter. Here, Harry Cliff explains how the LHC works and what scientists hope to reveal as they unpick the fabric of the Universe we live in...

Read the article then tell us what you think...

[chris]

They've actually published the first data from the LHC already!

Here's the abstract:

"Abstract  On 23rd November 2009, during the early commissioning of the CERN Large Hadron Collider (LHC), two counter-rotating proton bunches were circulated for the first time concurrently in the machine, at the LHC injection energy of 450 GeV per beam. Although the proton intensity was very low, with only one pilot bunch per beam, and no systematic attempt was made to optimize the collision optics, all LHC experiments reported a number of collision candidates. In the ALICE experiment, the collision region was centred very well in both the longitudinal and transverse directions and 284 events were recorded in coincidence with the two passing proton bunches. The events were immediately reconstructed and analyzed both online and offline. We have used these events to measure the pseudorapidity density of charged primary particles in the central region. In the range |η|<0.5, we obtain dN ch/dη=3.10±0.13(stat.)±0.22(syst.) for all inelastic interactions, and dN ch/dη=3.51±0.15(stat.)±0.25(syst.) for non-single diffractive interactions. These results are consistent with previous measurements in proton–antiproton interactions at the same centre-of-mass energy at the CERN Sp  S collider. They also illustrate the excellent functioning and rapid progress of the LHC accelerator, and of both the hardware and software of the ALICE experiment, in this early start-up phase."

[LeeE]

I thought the LHC was round, and so doesn't have a 'point'  (groan)

[Farsight]

I've got mixed feelings about the LHC. I'm all for experimental physics, but IMHO there are some serious problems with CERN press releases. Take for example "the mystery of mass". This is pure hype, because Einstein solved it in 1905 with E=mc². I also think it's wrong to suggest that the standard model will come crashing down if the Higgs boson is not detected - the standard model remains a work in progress, and the "consensus" on the Higgs boson is by no means universal. See http://www.publicservice.co.uk/feature_story.asp?id=13175 for a fairly good article. There's also an issue with "beyond the standard model" matters like supersymmetry. Another issue is that competitor experimentalists and theorists are not getting the attention they deserve because of the CERN promotional publicity. For example this guy: http://arxiv.org/abs/physics/0512265 was at ABB 50/25 in Bristol this week presenting a poster for his 2004 paper that has received no media attention whatsoever, and IMHO it deserves it. So when you ask "What do you think?", it all gets pretty complicated pretty quickly. As an aside, see http://physicsworld.com/cws/article/news/41257 re UK physics budget cuts which affect even ALICE.

[Soul Surfer]

The only way of increasing our understanding of the properties of matter at the most fundamental level is to observe collisions at ever higher energies the LHC will give us more information the only other process is to use extreme energy cosmic ray events and for them the original details of the collision will always be inaccessible.

As to whether the LHC Will enable the whole problem to be solves I very much doubt it and I am sure that we will have to use new high performance linear accelerators to get to the next stage and so on as long as our curiosity persists.

As a person who in the past has had to produce reports on the fundamental limits of various technologies.  I have always been amazed that once one st of limits has been found people use great innovation to circumvent the problem and new progress is made.

[LeeE]

I don't think it's true to say that Einstein solved the 'mystery of mass' but rather just established a number of relationships and equivalences.  Mind you, I don't think that finding the Higg's Boson will really solve it either; it will just establish new relationships.

[Vern]

Poincare was using the mass-energy equivalence equation before Einstein when he formulated the Lorentz Transforms.

[Farsight]

Point taken, Vern. And I shouldn't be too quick to forget Voigt, Fitzgerald, or Lorentz either. 

Lee: there really is no mystery. See http://www.fourmilab.ch/etexts/einstein/E_mc2/www/ for DOES THE INERTIA OF A BODY DEPEND UPON ITS ENERGY-CONTENT? If you heat a container of gas, the molecules move faster, they bounce off the walls of the container with more momentum, and the mass increases. If you trap a photon in a mirror box, the energy of that system is increased and so its mass increases. Mass is simply a measure of how much energy-momentum is in there. There's no need for a Higgs boson for this, and even the Higgs field reduces to space itself. To lay it on the line, employing the "God Particle" to explain mass is hype intended to curry favour and help preserve funding.

The only way of increasing our understanding of the properties of matter at the most fundamental level is to observe collisions at ever higher energies

It just isn't true, Soul Surfer. Pair production and annihilation don't need ever-higher energies. People have offered coherent peer-reviewed explanations for the electron, but they get no publicity. It's not just Qiu-Hong Hu, it's former CERN scientists like Williamson and van der Mark too. They get sidelined into places like the cybernetics society, see http://www.cybsoc.org/cybcon2008prog.htm#jw. The thing is, once you can explain the electron, you can explain the proton. Yes, the LHC will give us more information, but there's other information, lost in its shadow for years. Some of it is amazing stuff, like http://photontheory.com/Kemp/Kemp.html which leads to the quantum of quantum mechanics.

[yor_on]

I for one look forward to the LHC and their experiments. As LeeE says they will most probably help us find new 'limits' and 'relations'. As the Higg's boson http://www.exploratorium.edu/origins/cern/ideas/higgs.html

I can accept that idea much more easily than I can gravitons. After all, it would be as a 'field' acting on 'attractors' like matter if I understands it right, 'warping' SpaceTime where it happens.

As for 'gravitons' it seems that M-theory wants it?
String theory that is. http://motls.blogspot.com/2007/05/why-are-there-gravitons-in-string.html

But I'm not sure, maybe there are other interpretations of it too?

[yor_on]

LHC

[Sparrowhawk]

Thank you Harry Cliff, for a really clear explanation of what is an impenetrable topic for a non-physicist.