LHC Season 2 Is About To Start Testing the Frontiers of Physics 61
An anonymous reader writes: The final preparations for the second run of the Large Hadron Collider (LHC) are in place. This week, it is expected to start taking new data with collisions at the record-breaking energy of 13 teraelectronvolts (TeV). There are a lot of expectations about this new LHC season. In one of CERN's articles, physicists tell of their hopes for new discoveries during the LHC's second run. "They speak of dark matter,supersymmetry, the Higgs boson, antimatter, current theory in particle physics and its limits as well as new theoretical models that could extend it."
No new physics == Michelson–Morley of the 20 (Score:3)
Darmok and Jalad... at Tanagra. (Score:4, Interesting)
On the other hand, if no new physics is discovered, could this be the Michelson–Morley experiment of the 2000s?
It could be "Shaka, when the walls fell!"
A valid question, and I like a well-turned metaphor ("it was a wine red sea"), but wasn't there a Star Trek episode essentially mocking that sort of usage?
When out president says something is "our Sputnik moment", the Tamarians would understand perfectly.
This could be "The river Temarc in winter!"
Different...no firm prediction (Score:4, Insightful)
On the other hand, if no new physics is discovered, could this be the Michelson–Morley experiment of the 2000s?
That's probably very unlikely. Michelson-Morley was testing a prediction of the best understanding of light at the time. The non-observation of changes due to motion through the ether was clear evidence that the best understood theory for light was wrong.
Now we have found the Higgs the established model, called the Standard Model, has no more predictions to make: we have found it all. The problem is that there are some phenomena which the Standard Model cannot explain, like Dark Matter, and it relies on some amazing fine-tuning of parameters to have such a light Higgs (the odd of this happening by chance are about the same as winning a lottery 5-6 times in a row...and if someone did that nobody would believe it was simple luck!).
The solutions to these issues involve speculation by theorists and there are multiple candidates. Supersymmetry is probably the leading one but if we fail to see SUSY in the coming run then I, and a lot of my colleagues, will probably start to doubt it as the most likely explanation. However even then it might still be that SUSY is the explanation but at a higher energy scale that we can reach and just a more-than-minimal variety of it.
Personally the thing I expect the most for us to find is Dark Matter. this is based on two broad assumptions that cut across many different theoretical models: that Dark Matter interacts through the weak force and that it was thermally produced in the Big Bang. If these assumptions are correct then the mass of the Dark Matter particle has to be in reach of the LHC. However this is still far from any sort of guarantee: there are other models for Dark Matter out there with good motivation which we would not see e.g. axions.
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Can you explain why it is found acceptable for the standard model to allow calculation of probabilities greater than one . . . to me that indicates it is some kind of simplified approximation that breaks down at high energies
To everyone else as well. The question is how high and in what way?
Higgs is in the Standard Model (Score:3)
Can you explain why it is found acceptable for the standard model to allow calculation of probabilities greater than one (one of the reasons the Higgs was proposed)?
The Standard Model does not allow for calculation of probabilities greater than one. The Higgs is part of the Standard Model and you only get this effect, called violation of unitarity, for processes like WW scattering if the Higgs is not there. Since the Higgs was found the SM is complete and there is no problem with violating unitarity.
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Mass was the bigger problem (Score:2)
Part of the beauty of the Higgs mechanism is that not only did it explain how the particles could have masses while the symmetries of nature we observe are preserved but it also called out the unitarity violatio
RPV SUSY (Score:2)
Any SUSY is going to provide a dark matter candidate.
Actually that is not quite correct. A majority do but there are searches conducted at the LHC for something called R-parity violating SUSY. In these models the lightest SUSY particle can decay and SUSY does not explain Dark Matter.
These models are generally less popular because there are very strong limits on them from existing data. In particular these models allow for flavour changing neutral currents and thing like baryon number violation and there are extremely strong limits on both processes not be
No assumption re: SUSY (Score:2)
Does the higher energy and luminosity have any real chance of creating dark matter that we didn't see at the lower energy
Nobody can really answer that: we are going beyond the energy frontier and nobody can really say for certain what, if anything, we will find. However if those two broad assumptions I stated above (weakly interacting and thermally produced) are true for Dark Matter then, barring some pathologically strange model for new physics, we should see Dark Matter whether it is from SUSY or something else.
The reason these assumptions put a limit on the mass is that the heavier the particle the earlier the universe
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You can see this best currently in Quantum Entanglement, which defies causality, shows effects which can be trivially explained with classical theory, and thus has become a sort of 'faith-based' science.
Rather than convincing me that all of particle physics is faith based, you've merely convinced me that you have a personal axe to grind. Unpersuasive.
November Revolution (Score:2)
I doubt any revolution in particle physics would ever come from *WITHIN* particle physics.
Really? It has already happened once with something called the November Revolution [wikipedia.org]. This was the discovery of the charm quark which completely revolutionized our understanding of what baryons and mesons were and ushered in the quark model.
Prior to that there was the prediction of anti-matter by Dirac followed by its discovery a few years later which showed that we could unite quantum mechanics and Special Relativity. Prior to that there was Rutherford's discovery of the atom which completely changed our
Re: No new physics == Michelson–Morley of th (Score:3)
It will be if it proves that dark matter does not exist.
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Ignoring previous results on the Higgs Boson;
No new physics/results from these collisions would STILL be a welcomed puzzle. It would mean that the expectations are wrong and thus indicate something is missing in the standard model.
Science has progressed equally in the absence of proof as with validation of expectations. It's the discovery and the adaptation of knowledge that is more important.
Well, not exactly (Score:2)
There are no "Frontiers" in Physics. Reality is just what it is, no more, no less. You can't really have 'frontiers' if there is no subject to limit.
However, our knowledge of these laws and of Physics is somewhat limited. So the headline should read: "Testing the frontiers of our knowledge of Physics". But I guess it couldn't fit in a tweet or whatever.
In any case, very exciting times.
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Physics is "the study of reality", so sure it can have a frontier: the borders of our knowledge. Or, as I like to think of it, the shore -- the bigger the island of knowledge, the bigger the shore of uncertainty.
Metaphysics, rumor has it, was the title Aristotle chose for his book on the subject because "there not a word to summarize all this stuff, but it's after my book on physics, so I'll just call my book AfterPhysics". Typical sequel quality, if you ask me.
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You are confused as to what physics is. Physics is a man-made invention, it is not reality and it could well be ALL of it is found to be incorrect. Thus it has frontiers, mistakes, misconceptions, dead ends...
My new Microwave (Score:1)
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Bboth spellings are recognized by standard American dictionaries as correct. My 1976 Webster's New Collegiate Dictionary has
weiner: var of wiener.
~1 microsecond (Score:3)
Now the sausage is probably only about half a nuclear interaction length (guess) so only about 18% of the protons will interact per sausage crossing and not all of that energy will actually be co
Re: My new Microwave (Score:2)
Wasn't this test inadvertently performed on a Russian scientist's brain a few years ago when the instrument was started when he happened to be hunched over with his head in the target area?
Being stoic and Russian and all that, he survived.
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Experiments producing and storing antimatter have been going on for decades, e.g. Fermilab's antiproton ring
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Well then. Happy waiting.
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There's antimatter in your body right now! Your body contains about 175g of Potassium [wikipedia.org], some of which is the radioactive isotope K-40 [wikipedia.org] which sometimes decays via the release of a positron and a neutrino - positrons are antimatter!
Re: I still think they will kill us (Score:2)
Plus, Monsanto.
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Knowledge is in itself the advancement of man.
Do you also live in fear from the magnatudes more in force and number cosmic rays hitting our atmosphere? Until we can build accelerators that can beat out all such events, I think we are safe.
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Wrong headed thinking, those reactions don't have Earth in their center-of-mass as the LHC does. We're DOOOOOOMED, DOOMED I tell you.
8D
Meh (Score:1)
I'll wait till it comes out on DVD.
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Dark refers to not interacting with the electromagnetic force, i.e. not producing or reflecting light/radiation. We "see" dark matter through its gravitational influence.
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Re:watched a movie yesterday (Score:4, Informative)
You're right: the LHC beams are made up of separate bunches of protons. These bunches only collide at the 4 detectors. If they collided anywhere else, there wouldn't be anything to detect the products of the collision, so that collision would be a waste. Until the collision in the detectors, the protons moving in opposite directions are kept in separate beam lines: http://lhc-machine-outreach.we... [web.cern.ch]. Here's a look inside the beam pipe: http://lhc-machine-outreach.we... [web.cern.ch]
The time between collisions is 25 nanoseconds, meaning there is 25 feet between each bunch (light travels at about 1 foot per nanosecond). When two bunches collide, there are only 20-30 proton-proton collisions because the protons are so small compared to the size of the bunches. By the time the next bunches arrive at the collision point, the debris from the first collisions are completely gone from the original collision point (about 25 feet away in all directions).
http://lhc-machine-outreach.we... [web.cern.ch]
Yeah, right (Score:1)