Will the LHC Smash Supersymmetry?

gbrumfiel writes "The Large Hadron Collider is just getting ready for its next big science run. One thing researchers hope it will find is evidence for supersymmetry, a theory that could help to unify fundamental forces and explain mysterious dark matter. But as Nature reports this week, the LHC has shown no signs of supersymmetry in data from last year's run. If super particles don't appear by 2012, then physicists might give up on the theory for good."

Comments

Naive Question

[Anonymous Coward]

Suppose they prove super-symmetry and find the Higgs Boson, what are we going to be able to do with it. Other than completing the theory, is there any practical use for this new found knowledge?

Genuine question, physics isn't my forté.

Thanks,

Re:Naive Question

[Rakshasa Taisab]

Pure research of this kind does not usually have any immediate applications that can be pointed to, so your question isn't exactly applicable. What we do know is that pure (or basic) research often enable progress in more practical oriented research.

Re:Naive Question

[Even on Slashdot FOE]

Honestly, "What can we do with it" generally gets answered after we can prove we have it in the first place, but I'm sure there's at least one theory that says supersymmetry allows arbitrarily awesome things like wormholes or something.

Re:Naive Question

[TaoPhoenix]

Didn't we have the same "what use is this" question after that math story the other day? It's like a oblique troll that something is Useless Until Proven Useful.

General Theory of Truth: If something is true, something cool can be done with it. No exceptions. Politics don't count.

I agree *you* don't need this, but someone out there has to know this stuff.

Re:Naive Question

[darenw]

That's like going back in time and asking Coulomb or Volta about what applications their research would have.

"I don't know. Well, if you could make a small enough electrochemical cell to hide in your pocket, with wires you could shock people when you shake their hands, as a practical joke. Hee hee."

One way supersymmetry would be useful is at the theoretical level - it gives particle physicists another mathematical tool for predicting yet other kinds of particle to hunt for. It might help with understanding dark matter. When we know enough about space time matter and energy, my secret hope is we'll have insights for building faster than light insterstellar ships, or something else awesome.

Re:Naive Question

[ByOhTek]

Politics do count - look at all the lies in politics, obviously politics aren't true. Your rule is not broken, no exception is needed.

Re:Naive Question

[Beelzebud]

I'm not sure anyone can give you a specific example but look at it this way: Know exactly how and why particles have mass, seems like a fairly fundamental thing to understand about the universe.

Re:Naive Question

[jellomizer]

Well this theory, if proven would be able to give engineers knowledge on more basic rules, and limitations that they can factor into their designs. Just as electricity was discovered it took a fair amount of time for it to be useful for anything, it took the discovery linking magnetism and electricity before anything of use could be invented. Other then that it was used for well just zapping people, and some cool sideshow effects, as most Electrical energy was generated via static electricity, and chemical, which was done on a low enough scale to be useful.

Re:Naive Question

[DeCappa]

What's the use of a new-born baby?

-Benjamin Franklin

Re:Naive Question

[AvitarX]

I bet it was more along the lines of "A Leyden jar that works more than once", or "Zombies!"

Re:Naive Question

[theMoleofProduction]

Once you find the Higgs there's a cut scene where God kicks in the door at Stephen Hawking's house, pistol-whips a nurse, and wheels Hawking away with a gun to his head. It fades to black and you see: "ACHIEVEMENT UNLOCKED: BOSON-NOVA!" The Level Up screen opens, you get to distribute skill points and pick a Level II perk, and then you move on to the next quest.

Re:Naive Question

[theMoleofProduction]

CRAP! I forgot to add SPOILER ALERT!

Re:Naive Question

[The_Wilschon]

Here's one possibility: All of our favorite science fiction stuff (things that would allow us to effectively have a galactic or even universal civilization) appears to be disallowed by special and general relativity. However, these things necessarily break down in some regard at the smallest (ie highest energy) scales. Understanding quantum gravity (if we can ever do so) will tell us just exactly how relativity breaks down at super high energies. It is possible that the particulars will show us a way to travel and communicate faster than light (think things like the Alcubierre bubble).

The LHC will probably not unlock the secrets of quantum gravity. However, understanding the lower energy phenomena like the mechanism for electroweak symmetry breaking, or supersymmetry (or technicolor, or a variety of other speculative theories) is a necessary step towards understanding quantum gravity. As such, I think that experiments like the LHC are vitally important to the extremely long term survival of the human species (we have to get off Earth and out of the solar system sometime within the next few billion years, at the very least).

As other posters have pointed out, this, along with all other speculative applications of what we learn from the LHC, are probably not going to be seen during our lifetimes.

Re:Naive Question

[icannotthinkofaname]

It's like a oblique troll that something is Useless Until Proven Useful.

Not unlike the user(s) posting the troll post(s), I daresay.

Re:Naive Question

[SlashV]

Hahahaa, I've never laughed so loudly at a /. post. Hilarious :)

Re:Naive Question

[maxwell demon]

When Faraday was asked by the finance minister what this electricity was actually good for, he answered: "One day you will tax it."

Re:Naive Question

[MightyMartian]

Basic research rarely has obvious applications, and yet it pretty much lies at the heart of all technological advances. Guys screwing around in the 18th century with Leyden jars doing all kinds of interest parlor tricks probably looked pretty silly on the face of it, as well, and yet the ultimate value of these early experiments was enormous.

Re:Naive Question

[maxwell demon]

If the HIggs Boson exists and create matter, understanding how is function could lead us to be able to create matter in the laboratory.

The Higgs boson doesn't create matter. It (or rather the corresponding Higgs field) creates mass. That is, assuming the Higgs model is correct, without Higgs there would be exactly the same particles, but they would be massless.

Re:Naive Question

[ObsessiveMathsFreak]

...and then you move on to the next quest.

Collect 8 top quarks and 3 anti-hydrogen atoms.

Re:Naive Question

[thesandtiger]

The troll in that thread was the idiot who didn't even read the summary where the answer to the question he had was given. In this case, I know I (and I assume the AC) genuinely want to understand what exactly this means because of a lack of understanding about physics.

The way I'd look at it is this:

If someone discovers a proof that P==NP, then even though we haven't found the practical solutions to some problems (factorization or whatever) yet, it means that there IS at least one "quick" solution. So, that basic knowledge has that potential practical application - even though we don't know how to do it yet we know it CAN be done, if this were so.

If someone discovers that super-symmetry or the Higgs is true or false, what does that mean? What practical applications, even in theory, would come from that discovery? I know that the basic research is important, but I'm curious as to what it might mean. Would we be able to then say "oh, hey, this means that even though we don't know how to do it, artificial gravity is possible" or time travel or whatever kind of thing?

Re:Naive Question

[ConceptJunkie]

Other than completing the theory, is there any practical use for this new found knowledge?

Duh! Flying cars, jet packs, bionic limbs, amusement parks on the Moon... all that stuff they've been promising us for the last hundred years!

Seriously though, the stuff this will give us in the decades to come is so cool and amazing that no one has even imagined it yet. Take a look back at harnessing electricity, harnessing nuclear power, discovering relativity and quantum physics and figure out what those things eventually gave us.

Of course, just knowing is itself worth the effort.

Re:Naive Question

[thesandtiger]

That isn't quite true. For example, even though we don't know if P==NP or not, people have ideas for what could be or could not be done in either scenario. We don't know *how* to implement a quick factorization algorithm, for example, but we know that if P==NP we *could* eventually figure that algorithm out because we would know that it must exist.

And the "theory that super-symmetry allows awesome stuf" is probably exactly what the original poster was asking about, and I'm in the same boat.

Re:Naive Question

[tendrousbeastie]

Its a fair question. Some abstract theoretical physics leads to huge new technologies, some leads to none.

For example, relativity theory (special and general) did not in and of itself lead to any great new machines or devices (although it lead to other developments in physics which did).

Whereas quantum physics lead to loads of stuff, not least lasers and semiconductors and hence modern computers and communications.

The only general rule is that you can't tell if a scientific discovery will have utility until it is discovered.

Re:Naive Question

[Jamu]

Your question is premature. Applications mostly come after we've worked out something's nature. Historically, for Physics, the answer is yes, and most of the world's economy will be based on it.

Re:Naive Question

[mu22le]

Suppose they prove super-symmetry and find the Higgs Boson, what are we going to be able to do with it. Other than completing the theory, is there any practical use for this new found knowledge?

Nobody knows, but neither did Maxwell 150 years ago when he formuleted his theory of electromagnetism, nontheless without it you wouldn't have radios, ipods or cell phones. Einsten had no idea what his general relativity was good for but without it you wuoln't have GPSs and Li-ion batteries.

I could go on for a while, but let me tell you that real scientists work because they want to understand nature better, regardless of any pratical use that may stem from their work.

Re:Naive Question

[Kjella]

For a practical application, you can just assume the model is correct. For example ancient swordsmiths knew lots about how to make microstructures in steel without ever being able to see it in a microscope. But it didn't matter, because it worked. Nothing directly is held up by this, if something needs supersymmetry to work we could just build it and see if it works.

However, the more you know the more chance you can come up with something intelligent to try. For example it's highly unlikely you'd come up with the idea of a laser without finding out how atoms and photons work. Of course you can do thought experiments but they have their bounds. If we find the Higgs boson and that is responsible for mass, maybe we can manipulate it? There's plenty possibilities but first we have to find it.

Re:Naive Question

[boristhespider]

supersymmetry doesn't unite the forces. you've got to do something else to do that, such as super(symmetric)gravity and super(symmetric)string theory. they're an extra layer (and a good few extra dimensions) on top of a "standard" supersymmetric model such as the minimally-supersymmetric standard model.

Re:Naive Question

[osgeek]

It probably has more practical use than the knowledge that Green Bay won the Superbowl.

Re:Naive Question

[John Hasler]

What we do know is that pure (or basic) research often enable progress in more practical oriented research.

Nuclear weapons, to be exact. Science brought politicians the bomb. They've been throwing money at physics ever since in hopes of something even better.

Re:Naive Question

[MobyDisk]

IANAP. There will be 1000 responses explaining why I am wrong. But every reply I've seen so far is "it might be useful for some undetermined future reason" which seems pretty weak. So at the risk of technical inaccuracy, here is my speculation:

The Higgs Boson is the particle that assigns mass to another particle. Once we understand it, it opens up a lot of questions and experiments:
- Can we create a Higgs Boson, thus creating artificial gravity? Tractor beams?
- Can we use them for signaling?
- Could we create gravity waves?
- Could we use them to store power?
- Could we create matter with no mass?

Re:Naive Question

[vegiVamp]

I'm not particularly up to scratch on high-end physics, either, but you're very much thinking in the right direction, I'd say: proof that a current theory holds it's ground, means you can start looking at the theoretical possibilities that flow from that theory as rather more likely to be possible, which will cause more attention to indeed go towards them, some of which in turn will eventually lead to me zapping to work instead of being stuck in traffic, so to speak.

All knowledge is potentially useful. Sometimes the methods used to obtain it are objectionable (Dr Mengele, for example), but knowledge in itself is always a good thing.

Re:Naive Question

[rgbatduke]

A more interesting question is what will happen if they don't prove supersymmetry and fail (once again) to find the Higgs Boson, and in fact find "nothing particularly interesting" (perhaps beyond insight into the quark-gluon plasma, which is already forthcoming) all the way out to its maximum energy across all experiments.

Lack of evidence is not evidence of lack, but it is worrisome. It leaves open the possibility that we are off on completely the wrong foot, that reality is really nothing like our models, and we might have to go looking for new physics to consistently explain things like particle mass and gravitation and cosmological deviations from gravitation currently wrapped up in the "dark matter/energy" hypotheses.

Come to think of it, we might learn just as much from failure as from success. As usual. Even if it is a very expensive failure, compared to the knowledge gleaned from it.

rgb

Re:Naive Question

[C0vardeAn0nim0]

i remember a story about benjamin franklin being asked by fellow congressman what would be the practical uses for electricity. his answer ?

"i don't know what it's usefull for, but i know that in the future you will taxing it".

so, there's your answer.

Re:Naive Question

[ironman_one]

Well, here is a story about a former Italian minister asking Alessandro Volta what "possible could be the benefit of electricity".( At he time electric appliances consisted of the " the Voltaic pile. A device able to give anyone a rather unpleasant chock but not much more.) Well, sad Volta, I relay don't know but sometime you might be able to tax it.

Re:Naive Question

[mcelrath]

You seem to be confused. You need at least twelve top quarks.

Re:Naive Question

[khallow]

Didn't we have the same "what use is this" question after that math story the other day? It's like a oblique troll that something is Useless Until Proven Useful.

I would use the term "truism" not "oblique troll". I consider the current tired slop, which passes for justification of science, to be abominable. If you do work in the sciences at the behest of someone else, I can only hope that you justify your work far better than what you did here. This is a reasonable question to ask and it is disturbing how frequently it is brushed off.

In the case of figuring out whether supersymmetry is a feature of the universe or not, it is worth noting that advancing fundamental theories of physics have helped us in the past. Quantum mechanics is the basis for the model of semiconductor physics which we have so successfully used to power wave after wave of computers. Relativity led to the discovery of fission, fusion, and a host of subtle effects that affect really precise atomic clocks. Quantum electrodynamics predicted the existence of anti-matter and explains free electron lasers.

Quantum Chromodynamics is the current state of the art. While I can't point to an invention enabled by the theory, the theory does an adequate job of modeling particle jets which are real phenomena experienced by anything which is exposed to very high energy cosmic rays. And it explains all the known particles that we have seen so far.

So justification #1, past success indicates likely future success.

As a result we have something like tens of thousands of people, who incidentally cost a lot to employ, exploring the boundaries of current physical theory. But they have a big problem, not a lot of observational evidence. This leads to justification #2, any new observations trim the thicket of theories and better focus this vast expenditure of society.

Third, it's not a primary target. Justification #3, it's a freebie that you might get from work that was going to be done anyway.

Fourth, we can already think of genuine applications. For example, if you can figure out how to reliably emit, steer, and intercept neutrinos, then you have a potential communication device which can operate through the Earth, even through the Sun. An obvious near future application of that is communication from a central point on Earth to deep sea subs (such as the US or Russia's submarine forces). It also provides a significant communication edge for high frequency traders. It's the only way someone on Earth could directly communicate with someone on the far side of the Moon (which always faces away from the Earth).

The reason this exercise is useful is because we have many ways to decide how to spend the money that gets spent on scientific output. Maybe it could be spent on other things of pressing urgency such as feeding children or marketing a business's existing product (depending where the money comes from). Even if you decide on a scientific expenditure, it is worth recalling that there are more than one possible destinations.

This is why it is important to have justification, one or more reasons why something is useful. Because someone has to decide what to try, even if it's left to the scientist with ideas rattling about in the skull.

Else, you might as well spend all that science money on me, Mr. Khallow. You'll get science (check!) and some really cool block parties, well, nation-scale parties. A bit more money might be spent on the parties than on the science, but that's ok. Science is being done. That's all that need concerns you.

Re:Naive Question

[kyuubiunl]

forté /for tay/ Adverb (or adjective) meaning âoestrongâ or âoeloud.â This word comes into English from Italian and is used chiefly in a musical context. Ex. Play this measure forté /for-tay/. forte /fort/ Noun meaning âoestrong point,â âoestrength.â This word comes into English from French. Ex. Housekeeping is not my forte /fort/.

Re:Naive Question

[craklyn]

Fundamental science's goal is to understand how the universe we live in behaves. We accumulate evidence about how the universe works (called "measurements"), and use it to rule out incorrect possibilities.

It's the job of others, such as scientists who don't work on fundamental research (called "engineers"), to decide what we can do with the universe we live in.

Re:Naive Question

[egomaniac]

If someone discovers a proof that P==NP, then even though we haven't found the practical solutions to some problems (factorization or whatever) yet, it means that there IS at least one "quick" solution.

Unfortunately, no, it doesn't imply a "quick" solution. All P=NP would mean is that these problems have polynomial-time solutions; it says nothing about how efficient those polynomial-time solutions would be. Your only guarantee is that for sufficiently large N, any polynomial bound is better than any exponential bound. It can still be ridiculously, phenomenally huge (like O(N^4000)), and "sufficiently large N" can also be a ridiculously large number. If you came up with a polynomial-time Traveling Salesmen algorithm that doesn't start to beat exponential time until you're handling 1,000,000,000,000,000,000,000 cities, technically you've proven P=NP, but in a completely useless fashion.

Re:Naive Question

[oliverthered]

They may not have found the higgs boson, but they did find something unexpected, well a couple of things.

Gluon soup is a kind of loose liquid type of substance.
Things where shooting off in directions that could not be explained by the known forces involved in the collisions. (not sure if they've sorted this one out yet).. apparently particles have a 'preferred' direction.

Re:Naive Question

[bigsexyjoe]

The poster didn't argue that it wasn't useful. They asked if any immediate use is known. Not a dumb question, because often we can think of a specific application for new physics or math. For example, if someone solves does P=NP, we would care pretty fast. Sometimes we find the utility later, and sometimes nothing is found.

Re:Naive Question

[TaoPhoenix]

It's one of those questions that can either be honest or a really slick troll.

Fair enough you went honest, and I agree the difference of a word or two can make all the difference. I wanted to call attention to a possible new cross-thread troll trend where, if it happened 4 stories in a row, would set a meme.

Re:Naive Question

[Walkingshark]

OMG I already killed thirty two iron atoms and none of them dropped any quarks! How the hell do these atoms not have any quarks in them?!

Re:Naive Question

[mjwx]

General Theory of Truth: If something is true, something cool can be done with it. No exceptions. Politics don't count.

No Politics do count, when a politician tells the truth something incredibly useful can be done with it. This has not been tested in some time however.

Re:Naive Question

[Slur]

I think the distinction would be, politics are always contingent by definition. Science may hone but it seldom needs to censure. Newton survives in spite of Einstein and Heisenberg.

Re:Naive Question

[m50d]

Mass, not gravity, so no good for tractor beams or gravity waves, and no better for storing power than any other particle. Creating matter with no mass (and using that for signalling, since it would travel at the speed of light) is... well, maybe. Probably only on quantum scales, but even that would be very useful for e.g. faster microchips.

Re:Naive Question

[jandersen]

Genuine question, physics isn't my forté.

A genuine answer, then: basic research has proven its worth many times in the past. Most if not all mathematics that is now fundamentally important originates from what was once thought of as idle speculation - interesting, but basically useless. Science was once one of the arts on par with painting and music; there is a story (about Platon, I believe): A young man once asked him, "What is the use (of maths)?" and Platon turned to one of his servants, saying "Give that man an abacus and send him away".

And so on - the point is that people who don't understand sicience often want science to concentrate only on what is useful, not realising that we don't actually know what will be useful until we know more. All great discoveries are based on first observing without the bias of having a purpose, then speculating about what the observations mean; it is only when you have some sort of meaningful hypothesis that you can begin to make use of your observations.

In many ways, the worst scenario will be if we confirm the theories, because then we lose one of the big unknowns - the theory will be complete, and we will have less opportunity to make completely new discoveries.

Re:Naive Question

[Tim C]

What are we going to be able to do with it? Who knows.

They had lasers sat around in research labs for years as experimental curiosities with no practical use. Now pretty-much every household in the developed world contains at least one, and some people carry them around on their key chains.

Re:Naive Question

[spiralx]

Quantum Chromodynamics (QCD) is only part of the Standard Model, which is what I assume you mean by "state of the art", the part that describes the strong nuclear force. The other parts are Quantum Electrodynamics and the theory of the weak interaction, which combine as the electroweak interaction.

Re:Naive Question

[progliberty]

Nobody had any practical use for radio waves until James Clerk Maxwell developed his equations for describing their behavior (the behavior of photons). It's a similar case with the behavior of other subatomic particles. The research has to happen, and intellectual scientific curiosity has to be encouraged and funded.

Re:Naive Question

[The_Wilschon]

The immediate neighbourhood of a black hole is likely to be extremely hostile to biology. Otherwise, this is really quite a reasonable idea.

A validated theory is a stepping stone ...

[perpenso]

Suppose they prove super-symmetry and find the Higgs Boson, what are we going to be able to do with it. Other than completing the theory, is there any practical use for this new found knowledge? Genuine question, physics isn't my forté. Thanks,

A validated theory is, if nothing else, a stepping stone to an even more complete understanding. From better understanding comes new, or improved, tools. There is sometimes a time lag between discovery and practical application. Sometimes decades, sometimes a century or more. Consider nuclear fusion (what the sun is doing), potentially a safe and abundant source of power. Figuring out how to build and operate a fusion reactor will require understanding a few theories that were at one time merely theoretical with no practical application.

Re:A validated theory is a stepping stone ...

[thesandtiger]

The question then that I would have is "Why don't people who are trying to come up with practical applications act 'as if' the theory were true?"

I guess what I'm getting at (I'm not the AC who started this but I am also in a similar boat, understanding-wise) is: Right now it seems that most physicists THINK this theory is true. If that belief is validated, okay, great, they know they're on the right track, but aren't they already basing a lot of ideas for steps further down the line on the notion that this might be true? And, if that's the case, then aren't people coming up with, or at least thinking about, practical applications based on that assumption?

To me, it seems like the really interesting result would be if this assumption of super-symmetry (or anything else in a particular theory that is widely believed) doesn't actually prove true or doesn't behave like it has to for the theories to be true.

In case I'm being obtuse, I'll use an analogy:

When people were making rockets, they had some theories about what might happen in space, or what might be needed for the rocket to work, or what might happen to the people on a rocket, etc. They behaved "as if" those theories they had were true, or, at least, "as if" the most risky/dangerous versions of their theories were true and designed accordingly. So, they launched rockets, people were in them, and some of their theories panned out, some did not.

What could be built if these theories are true?

And, I am totally 100% behind the idea of learning stuff just to learn it - even if there isn't a practical application, understanding the universe is important.

Bleh, sorry, sick as a dog and on massive doses of NyQuil so I ramble.

Re:A validated theory is a stepping stone ...

[tendrousbeastie]

There aren't any practical developments that can be made on the assumption that these theories are true.

It takes a £30 billion system like the LHC to even work out that the particles involved in these theories exists. Developing consumer (or otherwise) technology to make use the these particles is not within the reach of any modern organisation.

Re:A validated theory is a stepping stone ...

[khallow]

How long since Newton discovered the nature of laws of gravity and inertia did it take man to reach into space?

The reaching into space preceded Newton and was a significant inspiration for the laws of gravity. As to practical applications of the law of gravity, it was used (along with the first known application of the least squares method) by Gauss to find the position of Ceres in 1801. That's a bit more over a century after Newton's discovery of the law. I'm pretty sure the law was used well before to predict the future position of the four large Jovian moons (particularly to study occultations visible from Earth).

The laws of inertia had immediate practical application to the trajectory of cannon balls.

While we're still reaping the rewards of Newton's laws of motion and gravity, as well as their successors, it's worth noting that near future applications of the theory existed.

No private industry would sponsor ITER or LHC or Hubble Space Telescope.

I seriously disagree. We have counterexamples. Private industry supported the Keck Telescopes, for example. These projects mentioned above are currently too big for private support by 1-2 orders of magnitude.

Re:A validated theory is a stepping stone ...

[UnknownSoldier]

> The experiment always shows the truth^H^H^H^H^H reality and that is what scientists think.
FTFY.

Experiment don't show truth - they show reality -- which _points_ to truth. If you have two experiment, that give contradictory results, you don't have truth (yet), you have a paradox. It takes _further_ experiment, to come to the correct _assumptions_ and _understanding_ of the problem, to reach a valid conclusion.

> That's how science, especially physics, works. It's all about the Real World and real, hard observations.

Right, just like Dark Matter, Dark Energy ...oh wait. :-)

Re:A validated theory is a stepping stone ...

[m50d]

There are multiple competing theories and, as others have said, many free parameters. What we call "supersymmetry" is not a single complete theory, we're nowhere near the stage where you could design your microchip using supersymmetric effects and calculate what the distances needed to be. In terms of making theoretical calculations assuming that supersymmetry is correct, physicists are doing that already, that's how they come up with these predictions. But even calculating what the outcomes of quite simple particle accelerator collisions would be at these kind of energies takes months of supercomputer time - to the extent that it may actually be easier to try it and see than do the calculation.

Re:A validated theory is a stepping stone ...

[wrook]

The very equipment you need to verify your findings usually happens to be the same equipment you need to make applications. And its not like the first time out of the gate you are going think of the best idea to build the equipment you need. It takes lots of iterations and refining to build up the technology. There are usually a lot of competing ideas of how to do things, etc, etc. But if you don't even know that the theory is valid, why would you invest huge amounts effort finding lots of different ways to exploit the idea? Lots of stuff in science doesn't pan out. That's valuable too, but not terribly good if you had 1000 independent teams all finding separate ways to discover that, no it just doesn't work like that.

Re:A validated theory is a stepping stone ...

[marcosdumay]

"How long since Newton discovered the nature of laws of gravity and inertia did it take man to reach into space?"

To reach space it took a long time, but from Newton definition of something measurable called "force" to the design of machines that could be reliably produced in large amounts, starting the Industrial Revolution it took less than one generation.

and then

[Krau Ming]

Brian Greene can write another book.

Re:If super particles don't appear by 2012

[Anonymous Coward]

This is a moot point as everyone is aware, the world ends in 2012. Possibly the creation of these superparticles is trigger event, collapsing the entire earth into a 70 mile wide ball of degenerate matter, and finally eliminating Justin Bieber from the universe once and for all.

high enough energy?

[Krau Ming]

*warning* semi-naive physics question here: does the LHC smash particles at a high enough velocity (or energy?) to definitively solve these problems? does the absence of a Higgs boson from the previous experiments disprove supersymmetry, or are we not smashing hard enough?

Re:high enough energy?

[spottedkangaroo]

I'm wondering the same thing. I think that they're looking for the "lightest super partner." Even one such partner would be evidence even if most of the partners were too heavy to show up in the LHC. But I don't really know how heavy any of them are.

Re:high enough energy?

[boristhespider]

No. We can never smash hard enough to disprove supersymmetry unless we find something that directly contradicts it. To put it another way, if all the LHC finds is a Higg's and expected results from the standard model, it doesn't actually disprove supersymmetry since any model of supersymmetry has so many parameters that you can tweak a few of them and lift the superpartners back up above the LHC's maximum energies. That is *always* going to be possible -- theoretically a limit would be if we had particle accelerators that reached the Planck energy and people would finally be saying "hang on, something's up here; we should be seeing quantum gravity by now and we're still not seeing the quarkinos", but in reality we're never getting to anything like an energy that would rule it out.

What's a lot more likely in my mind is that more physicists will begin to drop supersymmetry and look at something else that may actually have observable effects at "low" energies while otherwise the supersymmetry bandwagon will roll happily on with slightly more tightly-constrained parameters.

The hope is that the LHC not only doesn't see supersymmetry but *does* see something utterly unexpected. That's what I want from it. (Actually I want specifically no Higg's boson, and no supersymmetry.) Something unpredicted would rule out supersymmetry not least because any supersymmetric model that could account for it would be a posteriori -- constructed purely to do that and most likely grossly ugly as a result. By definition something unexpected is not a straight prediction of supersymmetric theories, and any model constructed purely to explain it will be under suspicion.

Before getting onto the next bit, the Higg's is not associated with supersymmetry, it's part of the standard model and doesn't require supersymmetry to exist. The Higg's is the last part of the standard model that is yet to be observed. They're different topics, and the LHC is hoped to shed light on both of them. As far as supersymmetry goes, the LHC was built basically to give us a pointer for where to go beyond the standard model and forms of supersymmetry are currently the most widely-favoured options.

The fear (at least my fear) is that the LHC will find nothing. Squat. No supersymmetry, nothing outwith the standard model -- but from my point of view, that it does find a Higg's. That would appear to add support to the standard model, which is a bit of a pain because the standard model's already broken since we *know* neutrinos have to have mass and fudging the standard model to put them in is pretty contrived.

However, not finding a Higg's at all would be brilliant -- so strictly speaking, the LHC finding *nothing at all* would be good. Because the Higg's should be within its capabilities and if it's not there there'll be a lot of head-scratching going on, and I always prefer things being rethought and reanalysed over mindlessly employing techniques chiefly developed in the 40s with QED and brought to fruition in the 70s with QCD and the electroweak theory.

But, in all fairness, I'm not a particle physicist, I'm a cosmologist.

Re:high enough energy?

[boristhespider]

most of them are pretty damn heavy. i believe the lsp is expected (from some models of supersymmetry) to show up in the lhc but it's easy enough to make sure it doesn't. if an lsp is found then at least part of the dark matter problem will be found, because that thing's basically stable and doesn't interact with us in any way.

warning: unfocused and off-topic rant ahead.

what's going to upset me is if an lsp is found (which i see as pretty unlikely, in all honesty) people are going to be shouting about how they've solved the dark matter problem -- they haven't, they've found that an lsp exists and is guaranteed to form *part* of the dark matter. there are plenty of other candidates and unfortunately i've been in physics long enough to realise that when there are about 15 or 20 candidates for something, most of them are there in some respect. i'll not be surprised if dark matter comprises of an lsp, massive neutrinos (we already *know* they're a dark matter, just not how significant they are if at all), relativistic corrections to the naive newtonian models of galaxies (galaxies are not living in flat space, they live in curved space which for spiral galaxies is cylindrical), a misapplication of the friedman equations in cosmology (the issue there being that they describe the universe "on average" and yet we haven't the faintest clue how that "average" is taken), and probably a host of other things i've forgotten and even others that have never been thought of yet.

Re:high enough energy?

[gwoptics]

Yes. No. The LHC might be the last collider to provide enough energy to find something really exciting. But, yes, a no-discovery so far does not mean anything but if in a few years time the LHC has not seen a new particle this would be a significant result. Andreas

Re:high enough energy?

[geekoid]

well, if it predicts something, and we show that that something doesn't happen then the theory needs to be change to fit the new data. If it can't be changed, then it's dead.

If I say gravity cause something to fall at a rate dependent on it's mass, and then do tests that show that mass is irrelevant to the rate of fall I have disproved my statement. That I can say either 'gravity' doesn't exist or that it exists but mass is irrelevant to the rate of acceleration during a fall.

Re:high enough energy?

[sweetser]

As a cosmologist, how do you feel about rethought and reanalysis of 1. The particles that cause inflation, 2. Dark matter needed for various galaxies and clusters of galaxies, 3. Dark energy needed for the accelerating universe?

There are problems with the classic big bang model, with velocities seen in galaxies, and the acceleration of the galaxies. My money is that all of these are hard math problems, not a new type of matter. I even have a specific equation I would like to apply to these problems in particular, but I am not good enough at relativistic rocket science to give it a go.

I am with you on the no Higgs/no supersymmetry.
Doug

Re:high enough energy?

[mcelrath]

Unfortunately physicists stopped looking for falsifiable theories a long time ago. They're bad for your career. They also forgot about Occam's razor. Supersymmetry is not a theory, but a principle, the simplest theory built upon it has 120 new free parameters. That's to be compared with the 19 of the Standard Model. It may solve one or two problems, at the expense of 120 new ones. As a consequence, it is nearly impossible to disprove supersymmetry. (and definitely impossible using only the LHC) One can always push the mass scale of super-partner particles above the energies of the LHC, and the theory lives, though it is now somewhat uglier.

Despite the fact that scientific advancement is always predicated upon reductionism we've created a very large pile of theories, each with a very large number of parameters, that have the same property of being un-falsifiable. This is essentially a consequence of the "publish or perish" nature of modern academic science. A theory with 120 free parameters represents many career's worth of exploring those parameters, in the hopes that one lucky guess and you might win the lottery, and your theory might be real. Hypothesizing a new symmetry, new force, or new particle (with no evidence whatsoever) and exploring its consequences is a game that increases the complexity of the theory, but is a good career path, as it generates an infinite number of papers, but bad for science, since it reduces physicists to monkeys at typewriters, trying to produce the works of Shakespeare. Such brains could be put to better use. We assume we already know the rules of the universe, and we apply them to make new theories. However it is demonstrable that we don't even know the rules. Even with supersymmetry (or any of the other theories), certain calculations give results in contradiction to our observed universe.

Let's contrast that with the way science is supposed to work. Let's try to take those 19 parameters of the Standard Model, and make it 18, or 10, or 1, or 0. For comparison consider the modern theory of Quantum Electrodynamics. We once thought magnetism and the electric force were separate. Feynman, Dirac, and many others built the modern theory, in which they are different aspects of the same force, the coupling constant of which is now one of the most precise measurements in all of science. However making simpler theories is time consuming and error prone, full of blind alleys and fruitless hypotheses that must be navigated. Science does not proceed by "Eureka!" moments in which everything is suddenly clear. It's painstaking work of mapping out what doesn't work, to clear the way for what does. If the path to a better theory were clear, everyone would build a highway to it. To find it, one must enter the wilderness. This is a career killer. Blind alleys are time consuming to navigate, and do not result in publications. During that time your colleagues will look at you strangely and wonder what the hell you're doing with your time. You will soon find yourself without a job.

On a positive note, no matter how degenerate our theories become, experiments like the LHC are our saving grace. They beat us over the head with a blunt instrument, and force us to face reality. In the words of Sherlock Holmes, "It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts" and that is the situation modern theoretical physics is in. We are theorizing without data, and building theories to explain statistical anomalies and backgrounds. The LHC will discover the origin of mass, whether it is the Higgs particle or not (and whether supersymmetry is participating or not). The LHC is far, far more important than all our fancy theories. We should always take data. It is how we learn. The notion that theorists have correctly guessed at the structure of the universe, absent any data, is naive.

-- Disgruntled and angry, unemployed theoretical physicist

Re:high enough energy?

[kittylyst]

"To put it another way, if all the LHC finds is a Higg's and expected results from the standard model, it doesn't actually disprove supersymmetry since any model of supersymmetry has so many parameters that you can tweak a few of them and lift the superpartners back up above the LHC's maximum energies."

Errr, not really. What you said there is pretty much akin to tweaking Newtonian physics by adding small additional terms to produce large-scale structure which matches observations. Or claiming that a geocentric model is fine because, y'know, epicycles can totally cook up anything required to fit observation of the solar system (NB: Please Note: I'm not a gravity bod).

The big problem with a lot of SUSY theories is vacuum stability.

One line of argument goes that something like this: "If there isn't a member of a Higgs n-let below a certain mass, then the vacuum is no longer stable. So by ruling out Higgs at various energies, we rule out certain classes of possible SUSY. As the mass at which we've ruled out Higgs gets higher and higher, the SUSYs which still aren't ruled out get more and more contrived."

At some point (and it's a point which most reasonable people would agree is now not too far off), SUSY stops looking like a like a fundamental law of the Universe and more and more like a hack-job.

Re:high enough energy?

[mangu]

But, in all fairness, I'm not a particle physicist, I'm a cosmologist.

What I want from cosmology is the same thing I want from the government: no inflation. A theory that needs a 78 orders of magnitude adjustment doesn't seem quite right to me.

Why not assume that the answer to the horizon problem is that under some circumstances FTL might exist? The problem with relativity is that it denies, in a somewhat dogmatic way, the existence of one absolute inertial reference, when we know there is at least one local reference that's "more inertial" than others because it's at rest with relation the the cosmic background.

In 1905 Ockham's razor was favorable to relativity because the microwave background wasn't known, but today we do know that it exists. Perhaps we have one reference where simultaneity can be defined in an absolute way, and the lack of simultaneity in other references is just an illusion caused by perspective. After all, there are many experiments demonstrating Bell's inequality that seem to indicate simultaneity in remote events.

It would seem to me that in the conditions shortly after the big bang there could exist conditions where some physical parameters were communicated instantaneously across the universe by quantum effects, this is at least no more unbelievable than cosmic inflation.

Re:high enough energy?

[Roger W Moore]

Unfortunately physicists stopped looking for falsifiable theories a long time ago.

Really? Care to explain how the Standard Model will survive if we fail to find a Higgs at the LHC then since the WW scattering cross-section will violate unitarity around 1 TeV without a Higgs. Hence we will either see the SM Higgs or exclude it. Seems pretty falsifiable to me.

Supersymmetry is not a theory, but a principle, the simplest theory built upon it has 120 new free parameters. That's to be compared with the 19 of the Standard Model.

Actually you will find that SUSY has exactly the same number of free parameters as the Standard Model. The only different being that with the Standard Model we have measured the parameters which has allowed us to simplify things e.g. no flavour changing neutral currents, mixing angles etc. These greatly constrain the free parameters. If SUSY is out there I would expect it to be similarly rapidly constrained once we can start measuring it. The problem you are complaining about here is that theory is ahead of experiment and whomever is out in front is in unknown territory which they cannot explain.

If you look at the 1950's and 60's when experimentalists were finding new particles left, right and centre the situation was reversed. Experimentalists were frustrated by finding all these particles and not know why there were so many and where all these apparently free parameters (mass, spin etc.) came from. It is always more fun to be in the group who is behind because then when you publish it is your paper which increases our understanding but that does not mean that something is wrong with the system - there will always be someone ahead.

Re:high enough energy?

[mcelrath]

Really? Care to explain how the Standard Model will survive if we fail to find a Higgs at the LHC then since the WW scattering cross-section will violate unitarity around 1 TeV without a Higgs. Hence we will either see the SM Higgs or exclude it. Seems pretty falsifiable to me.

I clearly was talking about supersymmetry here, in which one can push up the SUSY breaking scale as high as one wants. I did indicate that the LHC will discover the origin of mass...

Actually you will find that SUSY has exactly the same number of free parameters as the Standard Model.

You exemplify everything that is wrong with modern theoretical physics, and the inability of most practitioners to recognize the qualities of a desirable theory, the principle of scientific reductionism and Occam's razor. You have been brainwashed by the noise of the arXiv. Worse, you cannot count. I already cited the Wikipedia pages. Shall I enumerate the squark/slepton/neutralino/chargino mass matrix parameters, soft SUSY breaking masses and trilinears on Slashdot for you too?

Re:high enough energy?

[DCFusor]

We know standard model is broken much more fundamentally anyway -- gravity, singularity, math all blows up and can't be renormalized. One of the better kept secrets of physics over the years, sort of -- that there are two theories (SM and relativity) that prove out to the nth decimal in their own domains, but can't be used together at all. Most laymen don't know how truly embarrassing that really is. And as a cosmologist, how again was it that all that matter/energy of the big bang escaped the black hole it would have to have been? Or is the standard answer "it didn't, we live inside still"?

Me, I hope it does find something that gets rid of dark matter, dark energy (which are pretty awful bandaids to say the least), Mond (which is just too obviously a fit of a model to certain data) and gives us a way to make a model where we don't have to put in particle masses, speed of light and a bunch of other constants ad hoc.

But hey, that's just me. I never liked how Schrödinger's equations only take the magnitude of a complex number, toss out the phase, and then complain about indeterminacy. Duh, if you do that with even a Laplace transform, or FFT, you can't inverse transform without the data you threw away -- same result, indeterminacy. Dumb^2. Maybe god really doesn't play dice!

All those gross me out. I'd rather see a string or M theory that actually works and has all that fall out of it naturally. Extra dimensions have some interesting possible ramifications no one is mentioning, even if compact. From galaxy seeding from leak-through gravity, to teleportation -- if you're already everywhere in 7 of the 11 dimensions, for example, then it would seem "hetrodyning" might be how you project onto the familiar four. Heh.

Scotty, beam me up!

Re:high enough energy?

[boristhespider]

1: Pure phenomenology. No-one constructing inflationary models that I know of actually seriously believes that it's fundamental physics (at least, not after the second or third year of their PhD). What they *do* believe, frequently, is that the phenomenology can help guide a more fundamental theory. Personally I don't always agree with that; I think it can shroud a fundamental theory (in a similar vein to how cosmology is built on phenomenology that basically shrouds a very serious and neglected underlying issue).

Unless you're using the Higgs itself to drive inflation -- Guth's first model did this but it ran into problems with a graceful exit; it's recently been reawakened and re-examinded, though -- you're going to have a massive problem identifying an inflaton. We've not observed *any scalar fields whatsoever*. Even the Higgs remains elusive, though that might change in the near future. (Don't hold your breath.) So you immediately have a problem that what you're doing is specious. You can then either ground your inflaton in a well-reasoned model of high-energy physics or, and this is the standard approach, just invent a scalar field, call it the inflaton, and give it an arbitrary potential. So long as you make the potential flat enough that scalar field is an inflaton.

Basically it's phenomenology. But the people who do it are convinced it gives *suggestions* about what lies underneath, and in some ways they've got a point. Inflation works extremely well and it's standard to assume there was an inflationary epoch. You solve the horizon problem, the flatness problem and (if you believe in various GUTs) the monopole problem. (Basically -- why does the CMB look identical in opposite directions when the universe is too young for them to have ever interacted; why is the universe so fucking SMOOTH; and why do we not see any of these magnetic monopoles that GUTs produce in abundance?) Even more importantly, though, the quantum fluctuations of a scalar field coupled to gravity in the early universe produce tiny seeds that are basically exactly right. You can make models that get them exactly wrong but actually you have to work a bit; basic inflation made a prediction of those seeds, and when WMAP came along and looked at the CMB in unprecedented detail, it was dramatically confirmed. Basically those ripples had to be almost exactly Gaussian random, and "scale-invariant" meaning that the extremely large wavelengths were massively more powerful than the shorter wavelengths. That maps through to the formation of the CMB, when electrons condensed into protons to form hydrogen and light rays could suddenly free-stream carrying with them a photograph of the early universe. And it maps through even further, to the large-scale structure of galaxy clusters where we can look at those very same wavelengths. Much of a shift from those early imprints and that distribution is changed actually quite dramatically.

2: Dark matter is a big issue (well, duh). Basically "dark matter" is a catch-all term for whatever is causing rotation curves to deviate from the Newtonian prediction. I get irritated when people immediately assume it's a new exotic species of particle. I've put a couple of rants on this thread aimed at this kind of thing. My feeling is that dark matter in galaxies (and galaxy clusters) is made up of five or six different effects, *all* of which act as "dark matter", ie to flatten rotation curves: exotic particles perhaps, if supersymmetry is true; massive neutrinos since we now know that they are massive even if we don't know the mass, and neutrinos are so abundant that with *any* mass they form at least a dark matter even if it can't be the full dark matter (attributing the entire dark matter to massive neutrinos badly washes out structure on galaxy cluster scales); relativistic corrections coming from our naive assumptions that galaxies inhabit Minkowski (ie normal flat) space, since they don't, and that may -- *may* -- be able to account for up to roughly a tenth or more of spiral galaxies' dark matter; i

Re:high enough energy?

[boristhespider]

SUSY *is* a hack-job in my opinion. But what I meant is that in, say, MSSM, you've got well more than a hundred free parameters. Some of them are well-constrained; others aren't. Change a few of these and you can change the phenomenology. But as I've said a few times today, I'm not a particle physicist so I'm also happy to be told I'm wrong -- I talk with particle physicists sometimes, and the rest I get through the kind of academic osmosis that causes confusion worldwide... :)

Re:high enough energy?

[boristhespider]

You can get Schroedinger's equation in a totally deterministic (if rather contrived) manner by taking a totally classical system and adding a modification to the potential. If you then take the momentum potential (or action, however you want to phrase it) and the density you can bundle them together as basically the phase and the amplitude of a wavevector that... solves the Schroedinger equation. Totally deterministic and totally indistinguishable from standard QM. It's also very ugly and is riddled with conceptual difficulties, not least how you go about second-quantising to get something like a field theory, but even so, it's a totally deterministic formulation of standard QM.

Also, as basically a gravity theorist, it pains me to say it but GR is less reliable than the Standard Model. We can test it down to maybe 0.1mm and up to Pluto's orbit and beyond that, nah. It's because gravity's so damned weak. The other forces are much stronger and much better probed, and electromagnetism is the best known of all. QED is still one of our best theories. The problem with taking that too far is that then people have a bad habit of assuming gravitons must form the basis of a successful quantum theory of gravity and throw out geometry altogether -- knowing all the time of course (because they know this shit much better than I) that GR is non renormalisable and you're doomed to failure going at it in anything like a typical way. That way leads to string theories and supergravities and 30 years of intensive maths with absolutely zero solid predictions. A nice alternative is loop quantum gravity, which takes a much more conservative approach, takes geometry seriously, finds a way of quantising spacetime without gravitons and 7 extra dimensions, and has absolutely zero solid predictions for about fifteen years less intensive study. Other alternatives are brilliant, and all of them have absolutely zero predictions, to my knowledge.

As for the black hole question, it's not answerable within "big bang cosmology" because GR would have broken down before you get to the point that all the matter is within its own event horizon. Before GR is at all valid (even assuming we could use it that early) you can't extrapolate. So there's no way of saying that a black hole would inevitably be there because there might not *be* black holes in quantum gravity and on those scales probably aren't. (QG is expected to wash out singularities in some manner, and we have no idea what it's gonna do to event horizons on such small scales but if you've, say, granulised spacetime in some manner you've immediately got quantised areas and volumes as in loop quantum gravity, and that puts limits on horizons.) But it's all speculation... as is saying that there'd be a black hole back then because that extrapolates GR well beyond its regime of validity.

I wouldn't say "it didn't, we live inside still". I've heard people suggest that (I've even seen a Creationist cosmology that used external coordinates to chart the interior of a Schwarzschild hole, put us bang in the centre on top of a singularity and then used gravitational time dilation to prove that the universe is only 6000 years old. No shit, he did it. Of course, it relies on using the wrong time coordinate and the wrong coordinate patch in general, and then assuming that the singularity on the event horizon is real -- it's not -- and then that we can live in the centre of those coordinates, but it was still a stroke of genius.) But I wouldn't. The geometry is weird if you believe the extended Scwarzschild solutions and it's even weirder if you think we live in a charged or rotating hole. I don't believe any of it. I don't really have any firm beliefs one way or another, in all honesty, but definitely not that we live inside some big black hole.

I think I've made my opinions about dark matter and dark energy fairly clear somewhere in these comments, three times I think :) They are band-aids, and very ugly ones at that. MOND is an interesting one. No-one, including Milg

Re:high enough energy?

[boristhespider]

I wrote a long reply to this and lost it by being an idiot :( Anyway, I said firstly to dig out a copy of Joao Magueijo's book which may or may not be called "Faster than the Speed of Light" which postulates a changing speed of light and lets you do away with inflation. I think a lot of people would be happy if we could do away with inflation completely, but anything that replaces it has to repeat its successes, which are many.

As for the CMB, it doesn't violate relativity, it's *predicted* by relativity. All it is is a thermal bath of photons left over from the big bang. If you put in a big bang cosmology, that's what you get out. It doesn't pick a physically preferred frame any more than saying "This is MY car and that's a preferred frame!" It is a preferred frame - it's the one you're observing from, but it's not physically preferred. GR is all about being able to look at things from any frame of reference -- that's how it wipes the force of gravity; it notes that it's as fictional as centrifugal force (which it is) and changes reference frames to study it properly. The CMB isn't an absolute inertial reference frame, it just happens to exist. It's not imposed on or by relativity, but if you use a Robertson-Walker solution and put any photons in it at all it's forced on you.

Also it might interest you to know that in the standard cosmological model (phenomenological as it is) we don't even lock ourselves to the CMB. We actually lock ourselves to CDM most of the time, or lock ourselves to some frame that makes gravity look as Newtonian as possible.

As for simultaneity and so on... well, GR is wrong. Unfortunate, but true. How wrong and in what way we don't know, but yes, there seem to be issues.

Re:high enough energy?

[Bootsy Collins]

I left cosmology ten years ago after the dreaded third postdoc, so I've no doubt I'm out of the loop on a lot of things. But still, I'm surprised by a lot of your post. There's a bunch I feel like agreeing with/disagreeing with/asking about, but I don't have the kind of years it must have taken you to write that to reply! So I'll just pick out a couple of things:

A priori there's no reason to actually connect the dark matter needed for galaxies and clusters with the dark matter employed in cosmology. Cosmology is based on the Friedman equations -- one saying how fast the universe expands and the other saying whether it's accelerating. The "dark matter" in cosmology is just a number that appears in these equations. Identifying it with the dark matter in clusters appears to make sense... but only if you believe the equations are seriously physically meaningful.

Sure, logically you can make that argument. But you have a strong hint, don't you, from the fact that the numbers seem to work out. You have a number of independent ways of getting at the dark matter in clusters of galaxies -- (M/L), the cluster baryon fraction, weak lensing, etc. -- which are fairly consistent with each other. (we'll ignore stuff like the luminosity/temperature/mass functions of clusters, which also seem consistent with everything I'm going to say, but introduce new assumptions about density fluctuations etc.) In the first two -- (M/L) and the baryon fraction -- your method for deriving Omega_matter doesn't depend on the Friedmann eqns, or even the Robertson-Walker metric. I then take that value for Omega_matter, the flatness result from WMAP, and get a value for Omega_lambda. Now I *have* introduced cosmology, because in looking at the power spectrum of temperature fluctuations on the surface of last scattering, my relation of angular scale to redshift depends on the RW metric. And maybe, as you say, those equations don't mean anything physical, so that value of Omega_lambda doesn't really mean anything. But if that's true, then why does the hypothetical universe described by those values of (Omega_matter, Omega_lambda) do so well with observations on a broad range of scales -- such the high-z supernova data or the morphology distribution of clusters at low redshift -- things that wouldn't have to be consistent with each other if the Friedmann equations were meaningless?

(snip) But all this is built on standard cosmology - the Friedman equations. And here's the rub: these describe the behaviour of the universe on average and come from assuming that the universe is composed of homogeneous and isotropic 3D slices. But the universe isn't homogeneous and isotropic! If it was we wouldn't be here. Instead we're like a loaf of wholemeal bread, filled with chasms and filaments.

From my (admittedly dated) experience, nobody ignores the large scale structure of the universe in arguing for homogeneity/isotropy. They argue instead that we converge to it as larger volumes are considered. The surface of last scattering gives you an opportunity to test this idea, and it doesn't seem crazy. And we've gotten a long, long way with the Robertson-Walker metric, the derivation of which is built on homogeneity and isotropy. Granted that there have been surprises in the application of the redshift-distance relation (derivable from the RW metric), such as the Type Ia SNe data that got the whole "dark energy" mess rolling (I've always wanted to slap Mike Turner for coining that phrase -- can't think of one I hate more); but I can't see how inhomogeneity-induced perturbations to the RW metric would manifest themselves on large scales exactly the opposite from how they manifest themselves on smaller scales, in the near vicinity of structures.

Re:high enough energy?

[DCFusor]

Thanks for the nice, intelligent reply, Boris. I'll buy ya a beer and pizza sometime and we can go at it and have some fun! (Doug)

Re:high enough energy?

[boristhespider]

"But you have a strong hint, don't you, from the fact that the numbers seem to work out. You have a number of independent ways of getting at the dark matter in clusters of galaxies -- (M/L), the cluster baryon fraction, weak lensing, etc. -- which are fairly consistent with each other."

Sure :) It's a problem for people like me who more or less oppose Lambda CDM -- anything that replaces it has to work as well as it. And it does work - extremely well. I'm very uneasy about the physical content of it, but up to first-order perturbations it does work well. I guess my main objection to it is that at the current epoch (say redshifts lower than 1) the universe is increasingly badly-described by Lambda CDM.

And the philosophical underpinnings are pretty shaky. The phenomenology is extremely good - not perfect, but extremely good - but the underpinnings are wobbly.

"nobody ignores the large scale structure of the universe in arguing for homogeneity/isotropy. They argue instead that we converge to it as larger volumes are considered."

Yeah, sure -- but write down *how*. That's where you come very unstuck. The way I normally set up the model (because it allows for arguing an alternative) is that first you take the CMB, which is totally isotropic around the Earth (well, to one part in 1000 if you count the dipole, one in 100,000 if you subtract it though doing that is itself an assumption that's purely due to our velocity w.r.t. the CMB) and then assume the Copernican principle. That tells you the universe is homogeneous and isotropic "on average". You can impose that directly, which puts the universe in de Sitter (no), Minkowski (no) or anti de Sitter (no), all of which violate observations dramatically. So instead you foliate spacetime with maximally-symmetric spatial slices. That gives you the RW metric. Then assuming GR forces you to put in perfect fluids and recover the Friedman equations.

All well and good, but that's ignoring, for example, all the anisotropies on the CMB. Obviously at last scattering the CMB was extremely isotropic and the universe very close to homogeneous and isotropic. That's no guarantee it's anything like that now; the only constraints come from very large inhomogeneities fucking up the large-scale CMB (which is, by the by, fucked up but to be fair recovering the low quadrupole from inhomogeneities isn't that straightforward). Remember that the large-scale CMB is created by two things: primordial perturbations, those which were outside of the horizon when the CMB was formed; and late-time effects. The ISW is the best known of them and it's a massive problem for LCDM (well, that's a lie, the theory is only about 1.5 sigma away from the observation, but it *looks* very serious and the low quadrupole does worry a lot of people). They're on large scales because they're effects very near to us, and when things are near to us they look big. Sorry to sound patronising if I do - totally unintended. It's just it's that simple. Obviously it has to be something on the sky that subtends quite a lot of it - the ISW counts because it's the effect of "dark energy" so it's pervasive, and a Gpc scale void counts because, well, it's a fucking gigaparsec big, it'll subtend pretty much everything... :)

Anyway. The standard approach (to setting up the background equatons - I'm not knocking how people find baryon fractions and so on in clusters) also ignores the structures in the universe today. We've got an enormous problem with averaging in relativity -- you can't do it. You can average scalars, of course, but the average of a tensor field breaks covariance because it's coordinate dependent. That immediately should raise suspicions about the Friedman equations. Let's say for example that we want to do an average on the metric. That averaged metric may or may not turn out to be FLRW. We actually have *no clue*. Quite possibly it will so let's for the sake of argument say that on large scales, the universe is actually described by FLRW metric(s). But

Re:high enough energy?

[Patch86]

The hope is that the LHC not only doesn't see supersymmetry but *does* see something utterly unexpected. That's what I want from it. (Actually I want specifically no Higg's boson, and no supersymmetry.) Something unpredicted would rule out supersymmetry not least because any supersymmetric model that could account for it would be a posteriori -- constructed purely to do that and most likely grossly ugly as a result. By definition something unexpected is not a straight prediction of supersymmetric theories, and any model constructed purely to explain it will be under suspicion.

Two scientists are shipwrecked in a distant land, one a biologist and the other a physicist. They encounter a strange creature with the body of an otter, the beak of a duck, spurs like viper's fangs, and feet like a seal's. The biologist exclaims "My word, we've discovered a whole new species!" "Don't be ridiculous", the physicist replies, "you've just decided that to fit your observations- if you were a real scientist, you would have predicted it!"

Re:high enough energy?

[mangu]

It doesn't pick a physically preferred frame any more than saying "This is MY car and that's a preferred frame!"

Unless you are rotating. Then you have a centrifugal force. Why is it that if you are standing still against the CMB you feel no centrifugal force but if your frame has any rotation at all against the "distant stars" you have centrifugal and Coriolis forces?

OK, rotation has this particular property that translation doesn't have, but if there's one preferred frame for rotation why shouldn't the same frame be special with respect to translation?
 

Re:high enough energy?

[Roger W Moore]

I clearly was talking about supersymmetry here....I did indicate that the LHC will discover the origin of mass...

Sorry but you'll have to forgive me if I take a statement such as "Unfortunately physicists stopped looking for falsifiable theories a long time ago." as clearly being broader than just SUSY. Indeed your whole argument is phrased as a general issue with SUSY being one particular example. Hence my counter argument. I should also point out that it is not at all certain that the LHC will discover the origin of fundamental particle masses (not all mass), only that it will confirm or rule out the SM Higgs boson.

You exemplify everything that is wrong with modern theoretical physics, and the inability of most practitioners to recognize the qualities of a desirable theory

Perhaps this is just me being too modern but I always thought most desirable theory was the one which agreed with the data. SUSY might have a lot of free parameters but it is actually very good at explaining some of the problems with the SM and if we find it, it is very likely that SUSY breaking mechanism will remove most of those parameters. For example gravity mediated breaking models reduce the parameters to 4.5 (the 0.5 being a sign). Of course until we know what the breaking mechanism is we have to stick with the generic breaking models.

As an experimentalist I would certainly prefer a theory with fewer parameters (I loved working on direct CP violation with kaons), both aesthetically and to make my life easier, but science is about understanding the universe, warts and all. It is very satisfying when that results in a minimalistic theory but while you may think that it should always do that the universe may not agree.

Re:high enough energy?

[sweetser]

Wow! Thanks for the detailed technical reply. I read it twice and have bookmarked it. Grounded skepticism, nice.

Let's see if I can subtract away a bit of the jargon, to abstract the first two problems, so they sound similar. The horizon problem is that all parts of the Universe are traveling at the same speed, but they would always be too far apart from each other to reach an agreement on the speed. Let's call that the constant velocity problem instead. Everyone happens to be traveling at the same speed. Why they reach that particular speed is not known. Constant velocity problems happen in many physics problems.

The flatness problem is about the stability of the solution. Let's call it that then, the stability problem.

What the big bang needs is a stable, constant velocity solution that uses the force of gravity. So far, nothing accomplished, just a word game.

For the dark matter issue, I will focus on a smaller set of issues, just the rotation profile of thin disk galaxies. I don't read many papers in the technical literature, but did find one by Alar Toomre in the 1960s who figured out how to apply good old Newton's law to a disk galaxy. It is not trivial, and I really didn't understand how he applied elliptical integrals to solve the problem. Two things I do recall. First was that the solution was unstable. If a disk galaxy gets a slight nudge along the axis, it should curl up into a ball. It is not unusual to see one galaxy pass close to another (I think that is happening to the Milky Way), but the galaxies appear to be stable. Let's call this the stability problem.

Apply Newton's law to these galaxies, and you can get the velocities right as long as you stay near the core to the max velocity. It is out on the edge were problems live. Even where the stars don't shine, gas has been spotted going at the same darn speed. Everyone wants to go at the same constant velocity.

What the rotation profile of thin disk galaxies needs is a stable, constant velocity solution that uses the force of gravity. This is again a word game, it also does not cover the variety of cases seen for dark matter, but it is fun to construct a link based on reasonable abstraction of the problem descriptions (others may judge if I have been reasonable).

I do have a physics speculation for a stable, constant velocity solution that uses the force of gravity. Before I get there, I will define precisely what I mean by a physics speculation.
1. It must be a specific equation
2. It must be consistent with all partially successful earlier speculations

Apply this precise definition of a physics speculation to gravity. One could call Newton's law of gravity a speculation. It was the first, so didn't have any companions. It kept collecting more and more data to support it. About the only problem was a minor precession of the perihelion of Mercury. Jupiter all ready contributed 10x this amount.

Einstein spotted the problem with Newton's law soon after formulating special relativity: nothing travels faster than the speed of light, not even gravity. It took ten years to develop the field equations, then Schwarzschild found a solution, so that Einstein could then solve this small problem (he was giddy about this result for three days). The depth of the mathematical rewrite is stunning, but there is a way to pluck out Newton's law from Einstein's speculations. Those too have been confirmed for weak and strong fields.

As discussed above, Newton's law fails for the rotation profile of thin disk galaxies. Why not use Einstein's better law? It has been quantified how much that kind of shift would make for these low density, slow moving objects. This is the region where Newton does well in our planetary system, but fails for big stuff.

Is this a BIG failure? If you read technical literature or any popularization, they will trumpet the idea that this is beyond huge, super massive, because everyone describes it that way. Can you give me

Re:high enough energy?

[mcelrath]

I should also point out that it is not at all certain that the LHC will discover the origin of fundamental particle masses (not all mass), only that it will confirm or rule out the SM Higgs boson.

Going back to your original comment, you pointed out that WW scattering will violate unitarity within the energy reach of the LHC. So the LHC will discover the mechanism of EWSB, whatever it is.

For example gravity mediated breaking models reduce the parameters to 4.5 (the 0.5 being a sign)

MSUGRA is not a theory. It is an arbitrary reduction of the parameter space of the MSSM to make it more palatable to examine that parameter space. There is no reason or symmetry principle that e.g. the scalar masses should be equal at a high scale. I think it's a travesty that this theory has been so heavily used by experimentalists. It closes the mind to a lot of phenomena, and causes people to e.g. exclude reasonable mass ranges or decay modes from their analyses for "theoretiical reasons".

Agreed that a theory with a lot of parameters can parameterize a lot of things, and make anything agree with the data. By this logic the best theory is one with one parameter per experiment. Then you can fit everything. And indeed, in the absence of a compelling theory this is how experimentalists should parameterize their experiments. But, the science (on the theory side) comes when one realizes that you can actually remove some of those parameters... As for the LHC, we need to know what resonances, what masses, what spin, and what decay modes. Then we will spend a lot of time trying to figure out the relationship among them. This is an exercise that should happen after one has data, not before. The reason it has occurred before, in recent years, was the lack of any challenging data for about 20 years. So theory turned in on itself and started dabbling in fantasies.

Every true advance in science has come from reductionism. To think that the universe might just be a complicated mess is an ideological cancer caused by the lack of direction on the theory side. And don't get me started on the anthropic principle...

Re:high enough energy?

[kittylyst]

Bear in mind that SUSY was not intended to be a hack job. The Coleman-Mandula theorem is pretty definitive - if we want an abstraction that looks like QFT, then it has gravity, a gauge group (so in the real world SU(3) x SU(2) x U(1) at any energy scale we're ever likely to be able to detect / care about). SUSY is just the least messy way of extending symmetry in a way which doesn't violate Coleman-Mandula and which could provide constraints on the Higgs mass.

The original hope was that a) some existing particles would be found to be superpartners of other existing particles b) additional superpartners would be discovered relatively quickly.

That was all dashed hope, of course, but my point really is that SUSY didn't start off looking as bad as it does now. I never really believed in it, although some of the algebra was kind of pretty. Of course, having said that, I'll now be forced to eat my words (not for the first or last time), when the LHC finds a Higgs at the last gasp.

Re:high enough energy?

[Slur]

I'll venture something outrageous for fun. Every 'completion' of one order of symmetry exhibits a slight flaw which a higher order symmetry is required to reconcile. Thus instead of finding circles we end up with spirals, and instead of spheres within spheres we end up with - whatever 3D spirals would be...

Re:high enough energy?

[m50d]

Which "same frame"? There are infinitely many possible frames with the same rotation but different translation.

Re:high enough energy?

[spiralx]

Thanks for the comments, very interesting for someone who did his last bit of tensor maths just over a decade ago :)

Re:high enough energy?

[Raenex]

One of the better kept secrets of physics over the years, sort of -- that there are two theories (SM and relativity) that prove out to the nth decimal in their own domains, but can't be used together at all.

Considering that this the fundamental problem in physics (or at least was before dark energy and dark matter), and has been much talked about in regards to a "Theory of Everything" and string theory in popularizations by Hawking or Greene, and televised on shows like Nova, I don't agree that it is in any way some kind of "kept secret".

If the average layman doesn't know about this, it's probably due to poor education or lack of interest. There's been plenty of publicity about it.

Re:high enough energy?

[Roger W Moore]

Going back to your original comment, you pointed out that WW scattering will violate unitarity within the energy reach of the LHC. So the LHC will discover the mechanism of EWSB, whatever it is.

No, all that means is that we have to find that the WW scattering cross-section diverges from the SM (sans Higgs) prediction. There is no guarantee that this is due to the EWSB mechanism, although I would be surprised if it is not.

mSUGRA....I think it's a travesty that this theory has been so heavily used by experimentalists.

Having to pick a SUSY-breaking model is not nice but, unless you have a clever way of drawing a 100+ dimensional parameter space and enough computing power to be able to simulate a reasonable number of samples you have to do something to make the problem manageable. So it is less a travesty and more a necessary evil because we have to have something to aim at i.e. some idea of final states to look for. Generic analyses are no where near as powerful as focussed ones because backgrounds inevitably end up being a lot higher because if you don't know what your signal is you cannot be sure that a cut will not remove it.

Every true advance in science has come from reductionism. To think that the universe might just be a complicated mess is an ideological cancer caused by the lack of direction on the theory side.

As they say in financial adverts: past performance is no guarantee of future success! For example SUSY causes the force couplings to converge generally independent of the exact parameter set. While I personally may agree that it is unlikely that the universe is a complex mess it is conceivable to have theories with multiple parameters where the required behaviour generally comes out regardless of the actual choice of parameters i.e. only small variations would result. In many ways this would be perhaps even more beautiful than trying to reduce the universe to 0 or 1 parameter which gave us what we observe. So while I might agree that the universe is probably not a complicated mess I'm not willing to rule out that possibility.

Re:high enough energy?

[boristhespider]

But what marks the CMB out as special in your mind? The only thing it's got in your argument is that it's not rotating (which again involves basically just sticking to its monopole; some of the CMB anisotropies *are* from vorticity). But the same goes for the galaxy distribution on very large scales -- neither all that hydrogen nor the CDM we assume to sit there appear to be rotating either. I could pick either of those as my frame (and I normally pick CDM because it's convenient). "Rotation" is an intrinsic quality, it can be very well defined within the bounds of GR. You can make entire spacetimes that rotate, sure (the Goedel spacetime is probably the best known not least because it contains closed timelike loops, but more mundanely a Kerr spacetime is a rotating black hole), or you can have fluids that rotate in a spacetime (inevitably dragging some of the spacetime with them), or both.

There's no one "preferred frame" for rotation, I can pick any number of frames. I can attach them to particular fluids (such as the CMB, baryons, CDM, white-haired dogs) and then when I separate my fluid quantities out with respect to it, a particular rotation term emerges. It's all fine, I assure you.

Of course, if you don't want to trust the underpinnings of relativity it's a bit different, but the same happens with any metric-based theory of gravity so you'd have to be looking at something pretty exotic (at least for modern physics).

Re:high enough energy?

[boristhespider]

Gravity waves I believe is a matter of time... or that they really will be so weak as to be practically unobservable. Personally I think GR is too successful for there not to be gravitational radiation flying around, we just may never see it (though I think we will).

Gravitons are a different matter. They're a quantum field-theoretical construct ascribed perhaps more status than I'd like. You can derive (classical, linearised) GR by considering interactions of massless spin 2 particles, so you call them gravitons. Quantising them has turned out to be an enormous wild goose chase. I think it's not the way to go... btu I'm not a quantum field theorist, and one of the initial drivers of string theory was that one of the fundamental modes of the string turned out to be massless and spin 2. That wasn't in the original game-plan, it dropped out of it. That excited a lot of people and I can see why. But going with them means you more or less drop the geometrical interpretation of gravity (at least as a "fundamental" thing). In the mid 70s Weinberg wrote (in "Gravitation and Cosmology") something like 'no-one takes the geometrical interpretation of gravity seriously anymore'. I've a lot of respect for Weinberg (well, duh) but I disagree with him here - plenty of people do, just maybe not all the other particle and field theorists he had coffee with each morning...

Re:high enough energy?

[boristhespider]

Feynman was very open about how he enjoyed teaching because it gives you something to do in the time between ideas. It's kind of a way of living with the pain of breaking new scientific ground for a living :) The rest of us -- those not on permanent contracts but stuck in postdoctoral hell -- simply can't afford to do it. Step too far from the mainstream and you get no publications and, more importantly, no citations. That means you get no job. And unfortunately if Einstein were living now, relativity wouldn't be accepted unless he cut a deal with a university letting him put them as his affiliation. No university name = no publication. The system's even set up that you have to declare your affiliation. Certainly you can talk with a local department and might get permission to affiliate yourself with them, but then they're not going to be happy if you start publishing crackpot theories under their banner, so you'd better damn well make sure you've come up with the new relativity in your spare time from working as a mechanic because otherwise you won't get published and you sure as hell won't get back into academia.

(Seriously, it's very hard to leave and come back. I know one or two people who've done it. Otherwise you're left behind way too quickly.)

Re:high enough energy?

[boristhespider]

Group-theoretical epicycles. Marvelous...

well if the cubs win it all this year

[Joe The Dragon]

well if the cubs win it all this year (sadly not likely) then look out.

Re:well if the cubs win it all this year

[medv4380]

Just as they are about to win time will stop and their win will be unobservable.

Re:Politics

[TaoPhoenix]

Sorry, I wasn't clear.

I meant that cool stuff "can be done". "Whether it will be done" is the whole other problem with the political side. Sometimes the "can be done" is pretty hard, and politicians hate hard stuff. "We can have a moon base in 20 years" - but only if we were so scared we stopped most of our petty squabbling to do it. Seriously, you engineer types out there, how hard is it really to get a quad-protected airtight building to the moon? Put it at some kind of shade-crossover point to use the solar power but not get totally fried.

The problem now is we have a Terrorist meme that will instantly shut down any planetary science because we have decided we can't trust anyone to be on the base without blowing it up.

Luminosity, not energy levels

[pavon]

The energy levels for LHC will be staying about the same from now till 2012. The difference is that it will be collecting more data, and thus increasing the luminocity and statistical confidence that if supersymmetry is correct we would have seen something. This is the same reason that people were betting on whether Fermilab might find the Higgs Boson before the LHC; not because it is increasing energy levels, but because it has had more time to collect data and thus increase its luminosity. So it really is a matter of waiting until it has been running long enough.

No Higgs, no super symmetry, but a t-shirt

[sweetser]

That's my prediction, and my t-shirt: http://bit.ly/GEMtshirt

The idea: Maxwell's field theory is the best one we have, the basis of the standard model by swapping out the gauge groups. I figured out how to write the Lagrange density (every way energy can be exchanged inside a box) using quaternions. That is not so hard. Do you know how to factor (B^2 - E^2)? If so, then (Del A - (Del A)*)(A Del - (A Del)*) is the same thing, quaternion style. The quaternions cannot do gravity which involves totally symmetric changes in a metric. Therefore I used an even less popular algebra known by names such as the hypercomplex numbers or the Klein 4-group. Put that into the Lagrangian, which flips exactly half the signs. That makes my proposal for gravity.

Combine the EM quaternion rewrite with the hypercomplex gravity Lagrangian, but without that -(Del A)* thing which was subtracting away the gauge term. The gauge term is there in both the gravity and EM portion, but they wipe out each other, so gravity and EM apply to massive particles, but overall the Lagrangian is gauge invariant. The Higgs mechanism works via a clever solution. My unified standard model works via a clever Lagragian.

By the end of 2012, I will know if my t-shirt is wrong because the Higgs and/or supersymmetric particles are found, or my t-shirt is barking near the right tree.
Doug

Supporting material about the t-shirt
http://bit.ly/GEMIAPday1video
http://bit.ly/GEMIAPday1pdf

Re:No Higgs, no super symmetry, but a t-shirt

[pavon]

This stuff is way above my head, but I was wondering why the legend for the T-Shirt included × for quaternion multiplication, but × doesn't show up in the equation.

Re:No Higgs, no super symmetry, but a t-shirt

[sweetser]

A fine question. x is the "implied" multiplication. In C programming, you have to write A * B. In physics books, you write A B. So any implied multiplication uses quaternions, any box-times is hypercomplex.

The video is geared towards people who can do 1st year college calculus, or high school level if you are headed off to MIT.

Re:No Higgs, no super symmetry, but a t-shirt

[sweetser]

Gravity is literally a universal love force: no matter what you are made of, everything else in the Universe wants to get closer to you (whether you have showed or not). We all want to rush to the center of the Earth - a fall that would take a little over 20 minutes - but are stuck in an atomic-level traffic jam. How can we make universal attraction a law? My proposal is that the rule for multiplying 4 numbers together does not have a single minus sign. Without a minus sign, repelling does not happen. That is the accounting secret. The all-positive product is the box-times symbols on the t-shirt, or hypercomplex numbers/Klein 4-group on wikipedia. Physicists use something known as tensor calculus, and that blocks a direct road to this kind of multiplication.

Re:No Higgs, no super symmetry, but a t-shirt

[maxwell demon]

I just noted the t-shirt contains the word "Tolkien" ... maybe you better hide it from Tolkien Estate.

Re:No Higgs, no super symmetry, but a t-shirt

[maxwell demon]

BTW, I noted that your page contains links to bit.ly -- I can understand that on a forum (although I'd prefer preview.tinyurl.com), but for a web page? Are you trying to hide something?

Re:No Higgs, no super symmetry, but a t-shirt

[sweetser]

Nope. I can remember the custom bit.ly strings, but not YouTube strings. There may be better ways, but for now it is the way I know how to do it.

Re:No Higgs, no super symmetry, but a t-shirt

[sweetser]

A legit concern, but J. R. R. Albert Tolkien was Jewish, more by tradition than some sort of ultra-conservative flavor, and not born a Roman Catholic.

Re:No Higgs, no super symmetry, but a t-shirt

[Dachannien]

You could always follow the bit.ly URLs yourself and then post the YouTube URL that results.

Re:No Higgs, no super symmetry, but a t-shirt

[maxwell demon]

Well, I didn't mean the links you posted here. I meant the links on your web page. I guess the Mathematica file you link there is written by yourself, so you should not have any problems remembering its name, right?

That's what's wrong with Physics today

[gr8_phk]

It's not enough to find the Higgs and confirm the standard model. No, we must always be looking for strange new shit that violates the laws of physics as we know them. New particles, new types of matter, dark energy, broken symmetry, anything unusual. And if it can't be proven so much the better. Yes, I'm still waiting for them to realize that Keplers laws do not apply to galaxies, and the galactic rotation curve does not require dark matter to explain. Some of them also fail at application of the divergence theorem when it come to gravity (they basically assume any mass distribution can be treated as a point mass). Let's get the fundamentals right first before we run off looking for actual violations of the laws of physics please.

Re:That's what's wrong with Physics today

[BJ_Covert_Action]

No, we must always be looking for strange new shit that violates the laws of physics as we know them. New particles, new types of matter, dark energy, broken symmetry, anything unusual.

Isn't that kind of, you know, what drives science forward? Questioning the accepted laws as they are and seeking ways to expand upon them, generalize them, or all around uproot them to explain some currently inexplicable observation we've made?

Re:That's what's wrong with Physics today

[marcosdumay]

Hum? Kepler's laws do not apply to galaxies. Everybody knows that, and that's why people came out with dark matter. Also, altough the mass distribution of an spiral galaxy isn't very similar to a point mass, eliptical ones are quite well approximated by a point.

Re:That's what's wrong with Physics today

[Mr_Huber]

Er, they do realize that Kepler's laws do not apply to galaxies. They cannot, in fact, use Kepler's laws because they know quite well that the gravitational contribution of the stuff orbiting the center of mass is significant. That's why they use Newtonian physics in this situation. Our modern understanding of the evolution of spiral arms comes from this sort of analysis. They do not use Special or General relativity in this situation for two reasons. First is that the math is real hairy. Second, at these speeds and distances, it reduces down to good old Newtonian motion anyway.

As for Dark Matter, yes, there was a flash in the pan article a few years back about someone using General Relativity to analyze rotation curves and coming up with enough extra contribution to invalidate dark matter. The paper was up on ARXIV for about four hours before the first math errors were spotted and brought the whole thing crashing down. And even if that paper held, it wouldn't have explained results like the Bullet Cluster (http://en.wikipedia.org/wiki/Bullet_Cluster), where maps of particulate dark matter have been made. No modified gravity theory or assertions that dark matter goes away under SR or GR can explain those findings. Dark matter is real and we now have tools with which we can spot it. The trick is now to figure out what it is.

You seem to have a real misunderstanding of how physics, and all science, makes progress. Once we have theoretical models, they are, generally, perfect. A good theoretical model explains ALL available data, or it isn't a good model. Once we have a good model, the only way to improve it is to go actively looking for where it diverges from reality. Only with this new input, divergence from theoretical predictions, can models be refined, improved or even replaced.

That's why we're hunting the Higgs particle. Fact is, the Standard Model is slightly broken. Without a Higgs mechanism, predicted lepton mass does not conform with experiment. We have a gap right now, a discrepancy. We think we have a solution in the Higgs field. We could, I suppose, assume there's a Higgs field, pick one of the several variants and go with it. Or we could, you know, do some actual science and go looking for the thing and nail down its properties. Along the way, if we see some of the other things we're half expecting, super symmetry, discrepancies in gravity at the millimeter range, broken symmetries, energy leakage at high energies or anything else, so much the better.

The problem with science is not a lack of fundamentals. The problem is the theories are too damned good. Reality simply does not diverge from the theories unless we get into some really exotic conditions. Why do we need a superconducting particle collider with a diameter measured in kilometers? Because our models are frikkin' perfect for everything up to that. We know they're wrong. We know we can't reconcile GR with the Standard Model. But we won't know how to proceed until we can break either GR or the Standard Model. We don't know what piece of the puzzle is missing until we actually go and look at things.

Re:That's what's wrong with Physics today

[mangu]

Dark matter is real and we now have tools with which we can spot it

Or not. The Bullet cluster is one example that confirms some predictions of dark matter, but there still remain other problems, like the cuspy halo problem.

Reality simply does not diverge from the theories unless we get into some really exotic conditions

And that should get worse as our theories become more precise.

The problem with general relativity is that it gives very precise predictions for orbits in our solar system, but we do not have good measurements for bigger orbits. The Pioneer anomaly and the flyby anomaly could be indications of a deviation from general relativity. Perhaps a future theory of gravitation could explain both the Pioneer anomaly and galaxy rotation without the need for dark matter. However to test if the Pioneer anomaly really exists one would need to perform new, more precise, measurements which would be very expensive and take years.

The problem with ground breaking theories is that they create the need to rewrite large portions of current physics and that takes time and effort, so scientists usually are reluctant to accept them. That's what happened with special relativity, only when several different versions of the Michelson-Morley experiment seemed to prove in an incontrovertible way that aether drift did not exist scientists started looking for alternative theories. The main problem today is that experiments to detect limitations in general relativity are much more difficult to perform than the experiments they did a hundred or more years ago to prove the inexistence of aether drift.

Re:That's what's wrong with Physics today

[LordNacho]

It's not enough to find the Higgs and confirm the standard model. No, we must always be looking for strange new shit that violates the laws of physics as we know them. New particles, new types of matter, dark energy, broken symmetry, anything unusual. And if it can't be proven so much the better. Yes, I'm still waiting for them to realize that Keplers laws do not apply to galaxies, and the galactic rotation curve does not require dark matter to explain. Some of them also fail at application of the divergence theorem when it come to gravity (they basically assume any mass distribution can be treated as a point mass). Let's get the fundamentals right first before we run off looking for actual violations of the laws of physics please.

Well hey, there's still physical phenomena which are poorly understood. OTTOMH, sonoluminescence, turbulence.

Here's some more: http://en.wikipedia.org/wiki/List_of_unsolved_problems_in_physics

Re:That's what's wrong with Physics today

[DiamondGeezer]

No, we must always be looking for strange new shit that violates the laws of physics as we know them. New particles, new types of matter, dark energy, broken symmetry, anything unusual.

Isn't that kind of, you know, what drives science forward? Questioning the accepted laws as they are and seeking ways to expand upon them, generalize them, or all around uproot them to explain some currently inexplicable observation we've made?

Not in climate science you don't. If you apply such skepticism to something like the Greenhiuse effect or the utility of climte models, you grt called a Denier and worse.

Re:That's what's wrong with Physics today

[DiamondGeezer]

That was just written on an iPad. I'm a bad one-finger typist.

Re:That's what's wrong with Physics today

[Bootsy Collins]

Not in climate science you don't. If you apply such skepticism to something like the Greenhiuse effect or the utility of climte models, you grt called a Denier and worse.

Well, yeah, if you doubt the greenhouse effect, you'll get called worse -- like, say, stunningly ignorant -- since not only is the presence of a greenhouse effect on Earth well-established since the mid-1800s, but human habitation on Earth would be hard-pressed if it didn't exist. The terrestrial greenhouse effect is why the average temperature on Earth is something like 15 degrees C and not -18 degrees C.

Hint: "greenhouse effect" is not a synonym for global warming. Anthropogenic global warming is thought to involve an increase in magnitude of the greenhouse effect. But even if there's no anthropogenic global warming, the greenhouse effect would still be around -- and thank goodness, too.

Re:That's what's wrong with Physics today

[gr8_phk]

Also, altough the mass distribution of an spiral galaxy isn't very similar to a point mass, eliptical ones are quite well approximated by a point.

No. No they are not. A perfectly flat disk is not even approximated well by a point. Yes, the distribution of "flux" is symmetric about 1 rotation axis, but the flux density and hence the gravitational pull is not uniform in all directions at the same distance. This means an object won't orbit the disk at the same speed it would a point mass at the centre. That is exactly what I meant by misinterpretation of the divergence theorem - the total flux through a surface enclosing the mass is the same as that of a point mass, but the distribution is only uniform for certain distributions (like spherical).

Re:That's what's wrong with Physics today

[gr8_phk]

No, actually I am not the problem with physics. I'm not even involved. I read headlines about dark matter and I follow up by going to Wikipedia and find that the "expected" rotation curve is one that would be predicted by Keplers laws if start orbit the center of the galaxy and have no interaction with each other. That's clearly WRONG. I (being an engineer) write a simple program to plot the rotation curve assuming a uniform star distribution where everything interacts and I get the opposite problem for observation. That makes me happy because I know my simple model is wrong too - the distribution is not uniform like I assumed. So then I look at some of the information about how the real curves are measured - looks OK at first, so I don't dig deeper. I suppose the cosmologists who know better are too busy looking for wacked out shit to update the Wikipedia page with real information on the "expected" curve. I see stuff (here on /.) where they say something can be explained by a spherical diistribution of dark matter enveloping a galaxy. OMFG why would dark matter gravitationally effect normal matter but not end up with a similar distribution?

No sir, I am not the problem with physics. I am an engineer who first exhausts the tools I have to explain something before looking for exotic new shit to explain it. Occams Razor and all that - you know, simple explanations. The problem with physics is that ever since relativity, quantum mechanics, and the good old wave-particle duality (non of which I dispute BTW) nobody in physics seems to want a normal explanation for anything. I can not set the straight as you suggest, but I can insight a lively discussion of the problem on slashdot from time to time.

Thanks for playing.

...only until...

[cdpage]

They may give up on this theory, but only until they build a bigger collider.

Re:...only until...

[slick7]

Given enough power and time, they will eventually break something.
Werner von Braun said; "Research is what you're doing when you don't know what you're doing".

Dark Matter

[Maritz]

It would be exciting if superpartners to the current particle zoo were found, as it would give us a real neat and tidy explanation for dark matter, the neutralino being an example of a good candidate dark matter particle. Personally I think it'd be cooler than finding the Higgs but I guess we'll know once the data comes in.

Utility

[overshoot]

is there any practical use for this new found knowledge?

Physics at this level is like abstract mathematics: it exists for its own sake. Practical applications of this physics is like practical applications of number theory: just not in the plan.

Re:Utility

[JamesP]

Yeah, there are no real-world applications of number theory

cryptography, data compression, error correction, no sir, number theory is good for nothing sir

Re:Yes, maybe...

[slinches]

The way I understand it, the models predict that at a given collision energy level, there will be a certain probability that a Higgs boson can be detected. If a particle accelerator is run at this energy for a certain number of collisions (at lower energies this could take years due to the extremely low probabilities involved) and there is no indication of the Higgs, it means that the model is very unlikely to be valid. Supposedly at the levels the LHC has been operating without finding evidence of the Higgs, a subset of the hypotheses that predict measurable effects at lower energies are less likely now. Apparently, the upcoming two year run will cover a large portion of the current models' predictions and could invalidate them if it's not found. Since the most popular versions of the standard model rely on a measurable Higgs boson, not finding it could mean that we don't understand the universe as well as we think and would need new models that explain how particles have mass without it.

Re:Politics

[ReedYoung]

I hear ya. The problem in politics is that what "can be done" generally depends on 50% + 1 of all citizens agreeing that a thing should be done. And even then a minute but extremely noisy bunch of teabagger freaks who the media loves to cover can still be a major obstacle for as long as legislators believe they're significant, because they don't understand and haven't bothered to learn, that the media is ignoring much larger, legitimate grassroots groups (not corporate sponsored) and by and large letting Glenn Beck, et al get away with enormous lies about the number who turnout for his pathetic event, for example.

Sorry, I wasn't clear.

I meant that cool stuff "can be done". "Whether it will be done" is the whole other problem with the political side. Sometimes the "can be done" is pretty hard, and politicians hate hard stuff. "We can have a moon base in 20 years" - but only if we were so scared we stopped most of our petty squabbling to do it.

Ha!

Seriously, you engineer types out there, how hard is it really to get a quad-protected airtight building to the moon? Put it at some kind of shade-crossover point to use the solar power but not get totally fried.

The dividing line between sunlight and shade / "night" on any planet (or moon) is called its Terminator.

Warning: Off-Topic Rant WIthin

[boristhespider]

"And even if that paper held, it wouldn't have explained results like the Bullet Cluster (http://en.wikipedia.org/wiki/Bullet_Cluster), where maps of particulate dark matter have been made."

Not having a beef with you at all because I agree with basically everything you say, but this is the bit that really upsets me about dark matter studies. (Not you -- about dark matter in general :) ) There is almost certainly no *single cause* of what we call "dark matter" (which is, after all, just the observation of anomalous rotation curves. Ignore cosmological dark matter -- in principle that's totally unconnected and is just a term appearing in the Friedman equations which are totally phenomenological). We know that MACHOs exist. We also know that they're nothing like populous enough to be "the" dark matter. But we ignore them from then on, mainly because it makes our lives easier if we pretend they don't exist. But they do. We know neutrinos have mass. We also know that they're not massive enough to be "the" dark matter, but dark matter they certainly are. Warm, likely to dissipate from galaxies, but dark matter nonetheless. But we ignore them, too. We know an LSP is a dark matter, so for some reason we assume it HAS to exist and even attribute anomalous signals from the centre of the galaxy to dark matter annihilations and invent new channels for LSPs to interact and decay. But, for the sake of argument, let's say an LSP exists. Then it's a dark matter. And particle physicists will say it's "the" dark matter -- but it's not and it's entirely possible that actually it will only be the most significant component, the same as assuming the universe is hydrogen is a good first approximation and an appallingly shonky second approximation.

Add to that that it's undeniable that (spiral) galaxies rotate in a cylindrical metric and that just because the Newtonian potential is small doesn't change the fundamental nature of a spacetime, and it's at least suggestive. There are other papers out there that have looked at this and they've been better done and concluded that it can't be dark matter but it reduces the need by maybe 10% or 20%, in spiral galaxies. Add in a more complicated geometry to model the central bulge and maybe that'll go up to 25%. That's 10%, conservatively speaking, of a problem we're all masturbating over supersymmetry to solve potentially gone using century-old GR. Maybe an LSP is 90% of the dark matter, but it wouldn't be the whole thing. (Or maybe actually model it properly and relativistic effects *don't* alter the rotationc urves significantly. That's also cool.)

Then of course there's MOND. Is MOND fundamental? Nope, nothing like, it's pure phenomenology. But it fits galaxies way too close for comfort. You can ignore that all you like, but it's suggestive of at least some underlying correlation, if not actually modified gravity. The fact that it falls apart dramatically in clusters seems to argue against it being fundamental, but something fishy is going on.

As for the bullet cluster, even TeVeS (basically a relativistic generalisation of MOND) can fit that... if you play around and add in some massive neutrinos with a suspiciously high mass. Lower that mass and there's still a missing mass problem, but I'm happy with an LSP filling that if necessary -- but the case isn't really clear cut for dark matter having to be particle-like.

And it's certainly not clear cut for there being "a" dark matter. The way I see it it's actually clear-cut that there are various things going on, from new physics to a poor use of the old stuff, to supersymmetric particles, to actually just all the old stuff being there anyway as MACHOs and neutrinos.

Rant over. :)

Re:Politics

[ByOhTek]

The politicians are the Terrorists!

Remember kids, if you support a politician, a terrorist wins!

true, but...

[boristhespider]

it's not the theory that needs changing in that case, it's just the parameters in the theory. the theory itself is still fine, you just tweak a few numbers and suddenly it's "oh the lsp is up at 20TeV, sorry guys! you built that 15bn euro machine for nothing!" there's something like 127 free parameters in mssm which gives you a *huge* parameter space to run around in and hide from the experimentalists. play this game and the theory is still "valid". play it long enough and everyone else will give up and go and look for something else - but we might have to see a good few people retire before that happens.

Re:true, but...

[boristhespider]

:) Don't worry, I criticise cosmologists for doing the same. I've written a couple of wild unfocused rants on this story already and to be honest they're actually more motivated from frustration at astrophysics and cosmology than particle physics...

Re:Yes, maybe...

[tendrousbeastie]

From what I understand, there is a huge amount of chance. If you feed an amount of energy into a small point in space where that energy corresponds exactly to the mass of a particle (via e=mc2) then you will get that particle.

If you feed more energy into that area of space you may get that particle, or you may get other combinations of lighter particles whose mass/energy fit within the energy you've fed in.

As I understand it, to find the Higgs particle you'd need to use the correct energy level (i.e. fire a proton through the accelerator with just the right energy, not too low and not too high)

This was certainly the story for the J/ particle, only when they tuned their system to the exact energy (lower than the system was designed for) did they find it properly.

They'll turn it up from 700GeV to 1000GeV

[ReedYoung]

But colliders have failed to turn up direct evidence of the super particles predicted by the theory. The Tevatron at the Fermi National Accelerator Laboratory in Batavia, Illinois, for example, has found no evidence of supersymmetrical quarks ('squarks') at masses of up to 379 gigaelectronvolts (energy and mass are used interchangeably in the world of particle physics).

The LHC is now rapidly accumulating data at higher energies, ruling out heavier territory for the super particles. This creates a serious problem for SUSY (see 'SUSY's mid-life crisis'). As the super particles increase in mass, they no longer perfectly cancel out the troubling quantum fluctuations that they were meant to correct. Theorists can still make SUSY work, but only by assuming very specific masses for the super particles — the kind of fine-tuning exercise that the theory was invented to avoid. As the LHC collects more data, SUSY will require increasingly intrusive tweaks to the masses of the particles.

So far the LHC has doubled the mass limit set by the Tevatron, showing no evidence of squarks at energies up to about 700gigaelectronvolts. By the end of the year, it will reach 1,000gigaelectronvolts — potentially ruling out some of the most favoured variations of supersymmetry theory.

http://www.nature.com/news/2011/110228/full/471013a.html

So, they are planning on some increase in energy levels between now and 2012. Not an order of magnitude, I know, but 1000 is nearly 50% more than 700, and that's not "about the same" to me. So I think it's a combination of acquiring more data, and slowly increasing the energy levels (to LHC's maximum output, I assume?) until either supersymmetric particles are detected, or we have turned up the energy so much without finding anything that we have to give up on SUSY.

Good way to waste time

[Roger W Moore]

The question then that I would have is "Why don't people who are trying to come up with practical applications act 'as if' the theory were true?"

...because that would be a very good way to waste a lot of time. First question is "which theory" do you take to be true? Simple Standard Model Higgs or a Supersymmetric Higgs, or even a 2-higgs doublet model without supersymmetry? Next question is what is the mass of the Higgs bosons in your accepted theory? The problem with any unknown model is that there are free parameters which are unknown and so the phase space opens out so fast that it becomes impossible to concentrate any amount of effort on one particular area.

The other problem is that any effort may be completely wasted. For example Columbus set off to find a passage to India. Had you attempted to set up an Indian spice importing operation before he had returned you would have looked like a complete idiot.

To be precise...

[Kupfernigk]

I'm not even going to apologise for this pedantry, because I was at one time a member of the Royal Institution, before I foresook science for engineering.

In fact Faraday's joke was better than that, It was the Prime Minister (in those days called the First Lord of the Treasury, hence your confusion), and the Government had recently introduced some unpopular taxes. So Faraday's actual reply, "I know not, but I wager one day your Government will tax it" was doubly apposite.

The other one of these Victorian quotes is the response of the inventor of the dynamo when asked what use it was: "What use is a new-born baby?"

Different meaning.

[pavon]

What they are saying in that paragraph is that enough data has been collected to rule out the possibility of squarks whose energy is 700 TeV or less. By the end of the year enough data will have been collected to rule out 1 TeV squarks. However, the total energy of the collider will be 7 TeV for the entire duration (two 3.5 TeV beams hitting head-on). This is the same energy level that was met before it shut down for the winter break.

Re:Different meaning.

[pavon]

Err, that should be 700 GeV for the first number.

Utility is part of the plan

[Roger W Moore]

Physics at this level is like abstract mathematics: it exists for its own sake. Practical applications of this physics is like practical applications of number theory: just not in the plan.

Completely wrong. I don't know a single physicist who believes that. The reason we do what we do is because we are curious about the universe and want to find better ways to exploit it...but the first step in that is understanding. Practical applications are always part of the plan. The problem is that since we don't yet know the physics we don't yet know how to use it practically. 100 years ago "Physics at this level" was quantum mechanics which, since you are reading this article on a silicon based device, has turned out to be extremely useful. Of course absolutely nobody at the time could possibly have predicted the development of the integrated circuit from an understanding of quantum mechanics.

Even today early particle physics detector and accelerator technology is produced better medical imaging and treatment options. Just because we cannot imagine how today's discoveries will be used in 70-100 years form now does not mean that we don't fully expect them to be used for something.

Re:Utility is part of the plan

[Koda]

As Roger pointed out, quantum physics led to the development of silicon-based semiconductors, so it would be difficult to overstate the contribution quantum physics has made to human civilization.

To simply look at the economic impact of quantum physics:
- According to Scientific America in 2001, "...an estimated 30 percent of the U.S. gross national product is based on inventions made possible by quantum mechanics, from semiconductors in computer chips to lasers in compact-disc players, magnetic resonance imaging in hospitals, and much more." - http://www.sciamdigital.com/index.cfm?fa=Products.ViewIssuePreview&ARTICLEID_CHAR=BA5565B3-F0C3-4227-AA52-5C83A901C02
- Mary Kay Plantes tweeted, "35% US GDP derives from quantum physics..." - http://twitter.com/mkplantes/status/30090442213163008

I could go on, but my wife is calling me for dinner. [note setup for joke about Slashdot users versus women]

Re:Utility is part of the plan

[bcrowell]

Physics at this level is like abstract mathematics: it exists for its own sake. Practical applications of this physics is like practical applications of number theory: just not in the plan.

Completely wrong. I don't know a single physicist who believes that.

I'm a physicist, and I believe that.

Re:Utility is part of the plan

[mrsurb]

And of course number theory may have seemed useless at the time, but it turns out that useless things like factorising huge numbers into prime factors has practical applications for cryptography.

Re:Utility is part of the plan

[Roger W Moore]

...but I don't know you. ;-) However being a physics prof myself I do know a lot of other physicists.

Re:Utility is part of the plan

[bcrowell]

I think there's a problem because physicists have a strong motivation to exaggerate the practical utility of our work. If we claim that it might have some practical application someday, it makes what we're doing sound more worthwhile. It makes it sound like we're worthy of getting lots of money from the federal government.

An even more extreme example is the ridiculously overblown claims for the practical spin-offs from the crewed space program, which is basically pure nationalism and pork.

I don't do research anymore, but when I was doing research it was in experimental low-energy nuclear physics. I really, really don't believe that anything I did will ever have any practical application. Of course it depends on how indirect you're willing to make it. It's possible that something I did will have some indirect effect on some other field like condensed matter physics, since some of the phenomena are analogous.

FAIL it may never be ruled out

[Lawrence_Bird]

What has happened so far is that certain parameter spaces for some models of supersymmetry have been constrained. There are many models and many spaces from which to draw, so many that it may well be that LHC will never rule them all out.

Obligatory

[Tator Tot]

Supercollider?! I hardly know her!

Is supersymmetry really science then?

[tempmpi]

Since Popper we know something must be falsifiable to be science. If supersymmetry got enough tweakable parameters to account for whatever results might happen in our experiments, it doesn't seem to be falsifiable.

Re:Is supersymmetry really science then?

[boristhespider]

Don't absolutely rely on me for that - as I say I'm not a particle physicist. I'd more or less agree, except that you can do science degrees in pure maths, which is not only not falsifiable but it in principle has nothing to do with reality. You can play annoying word games and point out that any time you try and apply it to reality you're an applied mathematician. The same goes for things like string theory. But unfortunately high-energy physics will always be like this; there are limits that we can feasibly probe, but it doesn't mean the universe doesn't operate on those scales because clearly it does (or did). Unfortunate but true :( We may never really know how things behave. And I'm often swayed by Feynman's point that there may *be* no theory of everything and we shouldn't expect to find one because ultimately physics is an ensemble of algorithms. Set up a situation (say an electron and a photon approaching one another) and see what you expect to come out (scattering). Plug in the numbers and get a prediction. That's ultimately physics. Why should one set of algorithms play nicely with another? It's a bleak view but sometimes I feel there's validity in it, especially when I look at the long, fascinating and unhappy history of quantum gravity.....

Oh. My mistake.

[ReedYoung]

No doubt about it from the CERN article. Thanks for the clearer explanation of what they're actually doing than at nature.com, and for the links to cern.ch. It sheds a lot of light on luminosity. :-)

supersymmetry ain't...

[OldHawk777]

Observation problem: A particle in a field creates a field wave/state. There are not two *-particles. The *-particle/object is observed, or the *-wave/state is observed. A distant *-particle in the same field will show a wave/state relationship with the other particle, but never a particle relationship. Additionally, if the gravity field is uniquely interacting with another field (levity) as a pure gravity field bound by a pure levity field (or more fields) and/or localities/spots of varying strength single mesh-fields... well it could be interesting... %~P

A Question for boristhespider

[sgt_doom]

To boristhespider, a serious question: I have read repeatedly over the past thirty-some years that cosmic entanglement, or the EPR paradox, has been proven by experiments at the CERN reactors.

But then a prof of quantum mech at MIT stated that it has never been successfully proven to date.

Also, there appears to be some physicists who believe the existence of Hawking radiation has been completely disproven, while others aren't quite there yet.

Any opinions on the matter??????

Re:A Question for boristhespider

[spiralx]

With regards to the EPR paradox there's been lots of experiments done, the most famous probably being Aspect's in 1981; they all show that Einstein etc. were wrong, and local realism is violated by entanglement.

I very much doubt anyone is saying Hawking radiation is disproven; that's almost akin to saying QM and thermodynamics are wrong. This book is a very good overview of the last 30 years or so of black hole research, and has a brilliant title to boot :)

Re:A Question for boristhespider

[boristhespider]

As spiralx said, so far as I know no-one claims that Einstein was right in that. Entanglement appears to be a fact of life. Arguing over what it *means* continues, of course, but I don't know much about that.

Hawking radiation hasn't been completely disproven -- I'd like any physicist claiming that to resubmit their papers to the arxiv so we can all see their claims. There's a kind of equivalent argument that helps demonstrate radiation from horizons (though you'll have to take parts of it on trust). It's actually relatively quick to see that if you accelerate an observer (with constant acceleration), he sees radiation coming from the normal (unaccelerated) vacuum. It's called the Unruh effect (http://en.wikipedia.org/wiki/Unruh_effect). The interesting parts come because if you draw a space-time diagram of constantly-accelerated observers, you see "horizons" forming -- space is split into four patches and a constantly-accelerated observer can never cross between them. Well, unless he slams on the brakes and changes direction but then he's not a constantly-accelerated observer anymore. So we've got horizons of some form. (This is called Rindler geometry, by the by.) The other interesting part is the equivalence principle, locally equating gravity with acceleration. Via the equivalence principle, the Unruh effect predicts that radiation is emitted in the vicinity of horizons.

That radiation is also Hawking -- that is, Planckian -- though demonstrating that involves a very different calculation to Hawkings' original.

I'd be very suspicious of anyone proving to disprove Hawking radiation. It's always possible, I guess, that it doesn't occur in quantum gravity (and hence not in reality) because it's a semi-classical calculation involving quantum fields on classical spacetimes, but I'd be surprised. I don't know that anyone's developed any QM theory of gravity enough to test anything, though. So far as I know, they haven't (loop quantum would be the immediate suspect, and I've not heard that someone's been able to calculate the radiation or lack of it in LQG) but I'm not in the field so I can miss things.

Re:A Question for boristhespider

[sgt_doom]

Thanks for the reply, much appreciated, sir.

Re:Politics

[mcvos]

Sometimes when truth comes into contact with politics, cool stuff does happen.

Airplane joke

[overshoot]

You didn't get the part about number theory, did you? (See below)

Wrongo....wrongo....wrongo....

[sgt_doom]

"I very much doubt anyone is saying Hawking radiation is disproven..." Sorry, dood, but the book you've recommended I've already read, and in THIS VERY BOOK Susskind states he has DISPROVEN Hawking radiation. Your track record sucks, but thanks for the effort.......

Re:Politics

[Mister_Stoopid]

When truth comes in contact with politics they annihilate each other in a truth / anti-truth reaction. The truth / anti-truth reaction releases a few photon of s-radiation, (the s stands for stupid) which has the effect of making anyone exposed feel an uncontrollable desire to watch American Idol and drink Bud Lite.