Severian

I seem to be able to make it appear to spin either way at will. Very weird.

Huge waste of taxpayer's money. £9.345 billion apparently. We could have had a couple of colliders for that!

So what definition of 'real' and 'virtual' are you using? The usual definition, in my experience, is whether they are on-mass-shell or not - ie. whether or not they satisfy the mass-shell condition. Do you disagree with this? What is a 'static field' exactly? If I have a charge, I can produce a static field, yes? But now I suddenly switch off the charge, what happens to the field? It doesn't suddenly disappear everywhere at once. The effect must propagate out from the charge. So although a field may appear static, it is a continual transference of momenta from one object to another.

The Higgs boson will take quite a while. Exactly how long depends on the mass, but we are talking years rather than months. This is because it is produced in a rare process. Quantum Mechanically there is a small probability of a Higgs boson being created in each collision, but the probability is so small that a huge number of collisions need to be generated before you can see a Higgs signal. Other things, like supersymmetry or extra dimensions should be faster though, of the order of a year.

It is a rather hard question to answer because the technically correct answer ('yes') can be so misconstrued. Technically, every particle you observe has to be be virtual. By that I mean it is very slightly off-mass-shell, so doesn't obey [math]E^2 = p^2 + m^2[/math]. If it were on-mass-shell, it would live forever, so you couldn't observe it. Of course, since most measurements are made on relatively large timescales, it is very very nearly on-mass-shell, and indeed any macroscopic magnetic field is composed of relatively long lived photons, so they are very very nearly on-mass-shell too. (I think it was in this sense that Bob said 'no'.) The most on-shell photons we can observe are from the Cosmic Microwave Background.

I think he is saying that if you changed all space-length scales by a factor of 10, you would not notice (since everything you would compare to would also be rescaled) but you would notice if you rescaled time by a factor of 10. Therefore, space and time are not equivalent. I would counter this by saying that you would not notice the rescaling of time either, since all of your thought processes would now be working at the new scale.

I posted the official 'update' on this in the news thread.

Latest news, from the horse's mouth: From: "Rolf Heuer" <rolf.heuer@cern.ch> Date: 30 November 2009 08:19:54 GMT+01:00 To: "cern-personnel (CERN Personnel - Members and Associate Members)" <cern-personnel@cern.ch> Subject: LHC sets new world record La version française vous sera envoyée durant la journée. LHC sets new world record Geneva, 30 November 2009. CERN’s Large Hadron Collider has today become the world’s highest energy particle accelerator, having accelerated its twin beams of protons to an energy of 1.18 TeV in the early hours of the morning. This exceeds the previous world record of 0.98 TeV, which had been held by the US Fermi National Accelerator Laboratory’s Tevatron collider since 2001. It marks another important milestone on the road to first physics at the LHC in 2010. “We are still coming to terms with just how smoothly the LHC commissioning is going,” said CERN Director General Rolf Heuer. “It is fantastic. However, we are continuing to take it step by step, and there is still a lot to do before we start physics in 2010. I’m keeping my champagne on ice until then.” These developments come just 10 days after the LHC restart, demonstrating the excellent performance of the machine. First beams were injected into the LHC on Friday 20 November. Over the following days, the machine’s operators circulated beams around the ring alternately in one direction and then the other at the injection energy of 450 GeV, gradually increasing the beam lifetime to around 10 hours. On Monday 23 November, two beams circulated together for the first time, and the four big LHC detectors recorded their first collision data. Last night’s achievement brings further confirmation that the LHC is progressing smoothly towards the objective of first physics early in 2010.The world record energy was first broken yesterday evening, when beam 1 was accelerated from 450 GeV, reaching 1050 GeV (1.05 TeV) at 21:28, Sunday 29 November. Three hours later both LHC beams were successfully accelerated to 1.18 TeV, at 00:44, 30 November. “I was here 20 years ago when we switched on CERN’s last major particle accelerator, LEP,” said Research and Technology Director Steve Myers. “I thought that was a great machine to operate, but this is something else. What took us days or weeks with LEP, we’re doing in hours with the LHC. So far, it all augurs well for a great research programme.” Next on the schedule is a concentrated commissioning phase aimed at increasing the beam intensity before delivering good quantities of collision data to the experiments before Christmas. So far, all the LHC commissioning work has been carried out with a low intensity pilot beam. Higher intensity is needed to provide meaningful proton-proton collision rates. The current commissioning phase aims to make sure that these higher intensities can be safely handled and that stable conditions can be guaranteed for the experiments during collisions. This phase is estimated to take around a week, after which the LHC will be colliding beams for calibration purposes until the end of the year. First physics at the LHC is scheduled for the first quarter of 2010, at a collision energy of 7 TeV (3.5 TeV per beam).

Our theories of physics tell us that the strength of forces change with energy. For example, the strong force gets stronger at lower energies, which is why quarks are confined within particles like the proton. Given what we know about gravity, at low energies it is very weak (much weaker than the other forces), but we expect it to become strong at around 1019 GeV (called the Planck scale). If we collide particles at this energy, then the force of gravity would be so great that we might rip space-time and create a black hole. Now, the LHC will hopefully collide protons of 7 TeV each, giving a total energy of 14 TeV (14,000 GeV). However, protons are composite objects, and it is really the gluons inside that will collide, which typically have about 600 GeV energy each, though some can be much more energetic. So the highest energy collisions at the LHC will be a few thousand GeV. This is about 16 orders of magnitude too low to make a black hole, according to our expectations. However, there is another theory which suggests that gravity might not be so weak at low energies after all. It might just appear weak because the force is 'leaking' away into extra dimensions. Normal particles are forced to live in our usual 4 dimensions, but gravitons can travel in more. A gravitational mass is therefore radiating its gravitons out into these extra dimensions, so gravity doesn't effect us as much and may appear weak. If this is true, the real Planck energy, where gravity becomes strong, could be substantially lower than we thought. If it happens to be as low as 1 TeV, we could then potentially create black holes at the LHC. This would require something of a conspiracy since the extra dimensions would have to be just right to make the Planck energy 1 TeV. Also, if we had had this theory of extra dimensions years ago, we could have made the same claim of any collider ever built (since you could potentially engineer the extra dimensions to give you any Planck energy you like).

I like how the girl in the bottom right of that picture looks utterly bored while everyone else is jumping for joy.

It has been surprisingly muted actually. I think everyone is petrified that it is going to crash again. Even that picture I linked to was not allowed to be shown to the public today (I had it yesterday), so everyone is being quite careful. And for the record, I am a particle physicist and I do work on the LHC. I am just not based at CERN at the moment (though I was a few years ago).

Coincidentally, I am external examiner of a PhD exam on the 11th of December.

The energy is still below the Tevatron energy, so we wouldn't have expected to yet.

Here are the ATLAS ones: http://atlas.web.cern.ch/Atlas/public/EVTDISPLAY/events.html

Here is a link to the first events observed in ATLAS: http://atlas.web.cern.ch/Atlas/public/EVTDISPLAY/events.html

What if what I want is to be richer than you?

Is that true in today's society though? I think our definition of 'win' and 'lose' has changed somewhat. In modern days often a better measure is comparative wealth, so if someone else benefits more than you, you will actually be worse off.

I would settle for just having a competent government (at both local and national levels) but that is probably already too much to ask for.

When mooeypoo was made a mod, I also thought it was a mistake. But to be fair, she has handled herself quite well since being a mod, so in hindsight it was probably a constructive move. My bigger objection generally would be that the majority of the mods are pinko atheist liberals. It would be nice to see a little more diversity.

There is not such thing as being happily married. You just haven't realised you are miserable yet.

To create a 'magnetic black hole' you would need the electromagnetic coupling constant to become much larger. The QED beta function tells us how the coupling runs, and it becomes big only when it reaches energies of around the Landau pole, about 1040 GeV, if I remember correctly. This is about 37 orders of magnitude higher in energy than the LHC. You remind me of this.

I like skinny submissive girls who do exactly what they are told. Preferably blonde. A Tripolation has good taste.

My best moment was getting home from work just in time to get a big hug and kiss from my 3 year old daughter before she went to bed.

That is very subjective and depends on how you quantify 'evil'. I personally think the bombing of Dresden was evil too. I don't think we should be living our lives, measuring ourselves in comparison to others. Just because my actions may be 'less evil' than my neighbour's doesn't make me good and him evil. We should be judging ourselves on our conduct every day, being rigorous not to do any acts with think are morally compromised (however we may define that, and I leave that up to you). Personally, I would never have ordered the dropping of the bomb, because it is an evil act. [slightly off topic, but on a similar notion, I wouldn't kill one person in order to save the lives of millions.]

Fermion number conservation is just angular momentum conservation though, so it is not a terribly useful additional quantum number. Lepton and baryon number are better. Also, mass is not conserved.