io9 
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San Francisco, 11:40 PM
Mon Dec 14
25 posts in the last 24 hours
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11/14/09
11/14/09
11/13/09
(holds up a "#1 fan" foam hand) #largehadroncollider
11/13/09
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11/13/09
there are lots of scumbag terrorists in prisons who should be included in that. #largehadroncollider
11/13/09
11/13/09
Of course, the proton beams at LHC are much greater in energy but overall, it seemed to cause a lot of problems like seizures. #largehadroncollider
11/13/09
@Nefilim: I would not put a death row inmate in there... just in case.
And we don't have death row inmates in western Europe, since we don't have a death row to start with.
11/13/09
11/13/09
11/14/09
"Brighter than a thousand suns."
Not a metaphor,
Not a simile,
Literally true. #largehadroncollider
11/14/09
11/14/09
11/14/09
11/14/09
11/18/09
11/13/09
HAVE YOU SEEN THIS MAN?
BREAKING NEWS, this just in! There has been yet another massive setback at the LHC, when during a routine check, workers discovered numerous carrots, beets, and parsnips inserted into delicate machinery.
Already there are allegations of sabotage. These acts are said to be the terrorist plot of a group of moles (or even voles, sources aren't clear on the matter) which are part of a extremist Luddite sect known as "Mole-o-tov Cocktail". This terror cell is believed to take orders from the man pictured above. He is wanted for questioning by authorities, and if you see Him, please contact your local police department immediately.
This mishap is expected to set the project back by several more months as the machines are repaired and brought back online.
11/13/09
11/13/09
11/13/09
please bring about the zombie apocalypse
please bring about the zombie apocalypse #largehadroncollider
11/13/09
11/13/09
11/13/09
11/13/09
11/13/09
[www.news.com.au] #largehadroncollider
11/13/09
11/13/09
Oh, wait. Sat. was my birthday. Never mind. #largehadroncollider
11/13/09
11/13/09
11/13/09
11/13/09
11/13/09
@tetracycloide: #largehadroncollider
11/13/09
11/13/09
11/13/09
"One of the coolest parts about accelerators is that when the microscopic particles smash into the walls, they are moving so fast that they leave long tracks in their wakes."
So the LHC is basically a giant NASCAR track for particles? #largehadroncollider
11/13/09
11/13/09
11/13/09
"... the way they might under extreme conditions or in outer space."
Particles in outer space do not collide with the energies they have in the LHC, for two reasons: 1) typically, in outer space, they aren't as energetic in the first place and 2) even when they are (such as in cosmic rays), there are so few of them around any one of them that the chances of any collision are vanishingly small (technically, we say that their collision cross section is much too small).
So, the "might" applies well to "extreme conditions" but hardly to "outer space."
The extreme conditions the LHC targets are those in the early universe, when it was much smaller and hotter than today and when collision cross sections were, therefore, much larger.
It's interesting to add that cosmic rays are far more energetic than what the LHC produces but studying them is very hard precisely because their collision cross sections (with our atmosphere or with ground facilities) are far too small for our current detection capabilities.
In a sense, the LHC trades energy for size: it can't produce particles with as much energy as cosmic rays, but it can pack them much much much closer together, ie, in a much smaller region, thereby achieving a much higher density.
That's why it can study what amounts to conditions similar to those in the early universe.
"Often, researchers can gain information from examining these tracks"
The tracks are the primary means of obtaining information about particle masses, charges, and velocities.
Calorimeters are "containers" that measure a particle's energy by measuring the heat generated when the particle is stopped. But energy alone is not sufficient to identify a particle. You need its mass, charge, spin, and other characteristics.
Charged particles move in spirals in the presence of magnetic fields, and the curvatures of those spirals are a measure of their momenta. Using a particle's momentum deduced from the tracks and its energy measured by a calorimeter, it's possible to deduce the particle's mass.
Also, the direction they spiral (towards the left or towards the right, with respect to their motion) determines the sign of their charge (positive or negative).
The magnetic field trick above is useless for neutral particles (because they don't spiral), but they are identified by using so-called "conservation laws" (conservation of momentum, energy, angular momentum, charge, lepton number, and others).
It's a hugely complex jigsaw puzzle, when you come to think of it, to identify all the particles and the reactions they participate in. #largehadroncollider
11/13/09
11/13/09
Spin is a form of angular momentum, so it's determined by imposing the conservation of angular momentum.
Spin is a particle's so-called intrinsic angular momentum. There is also orbital angular momentum. Both participate in the law of conservation of angular momentum. #largehadroncollider
11/13/09
In other news, you are totally awesome. Thank you, as always, for clarification on physics-related topics. #largehadroncollider
11/13/09
"since technically most of the phenomena the LHC will measure are ones that only occur in outer space, I think it's still accurate."
Not really, since outer space in today's universe is, for the most part, empty and boring. I know I'm being a bit pedantic here, but it's only in order to help people understand something so fascinating and (lately) controversial a little bit better.
"In other news, you are totally awesome. Thank you, as always, for clarification on physics-related topics."
Thanks! You're very kind. #largehadroncollider
11/13/09
11/13/09
Thanks.
"It is probably also worth mentioning that many particles can only be identified by the pattern of their decay products"
Very true, and sometimes only by the decay pattern of their "decay parents", as was the case with the neutrino back when it was hypothesized.
The neutron decays into a proton, an electron, and an anti-neutrino but, at the time, no one knew about the neutrino (or its anti).
The decay of one particle (the neutron in this case) into exactly two others (the proton and the electron) necessarily fixes the energies of both products, but the experiment revealed a continuum of energies for the electron (over repetitions of the experiment, the electron was found sometimes with one energy, sometimes with another, and so on).
Eventually, it was suggested (by Pauli, if memory serves) that the neutron decays into a proton, an electron, and one or more neutral particles (the simplest explanation being just one neutral particle), and that's how the neutrino was "identified" (well, hypothesized - it was directly detected much later).
"supersymmetric partners of standard model fermions"
I think it will be tremendously exciting if supersymmetry is corroborated.
More so than finding the Higgs, in my opinion, because the Higgs is almost a done deal (if the Higgs doesn't exist, the Standard Model is in deep deep trouble).
11/13/09
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11/13/09
Don't worry, you'll still have Australia and some Africa. (I think, I'd have to check a non-Mercator map to be sure) #largehadroncollider
11/13/09
11/14/09
11/14/09
Sweet, I think we just invented quantum xenophysics!
11/14/09
11/15/09