This site is not maintained. Click here for the new website of Richard Dawkins.

← LHC results put supersymmetry theory 'on the spot'

LHC results put supersymmetry theory 'on the spot' - Comments

Neodarwinian's Avatar Comment 1 by Neodarwinian

Ugly facts killing less than beautiful theories. I never did see the extreme beauty of supersymmetry, but I am a mediocre mathematician!

Mon, 29 Aug 2011 20:51:57 UTC | #865301

John_Geeshu's Avatar Comment 2 by John_Geeshu

The honesty and commitment to truth displayed by Lykken is wonderful to see. Not all the world is drowning in unchanging dogma.

Mon, 29 Aug 2011 20:54:06 UTC | #865304

Jos Gibbons's Avatar Comment 3 by Jos Gibbons

The thing about things like supersymmetry is that they can come in multiple flavours that cannot be all falsified quickly; indeed, this article does mention the least simple version is the only one undermined by the new evidence. Perhaps an easier example is that of the Higgs boson, which the LHC is eagerly hunting. Are there any or not? According to the Standard Model, which has the simplest take on the question, there's one type of Higgs boson. We should be able to disprove this - if it is false - by the end of 2012. But even if we do, this won't mean there are no Higgs bosons. The simplest supersymmetric variant of the Standard Model features five Higgs bosons. Of course, the evidence this article discusses rules out that theory. I wonder how many types of Higgs boson (if any; Higgsless models do exist too) are really out there.

Mon, 29 Aug 2011 21:18:51 UTC | #865315

Steven Mading's Avatar Comment 4 by Steven Mading

So, does anyone want to take bets on how long before the first religious nutter tries to claim this as a failure of science? (Rather than what it really is - a demonstration of what makes science better than religion - accepting the facts when they prove you wrong.)

Mon, 29 Aug 2011 21:20:47 UTC | #865317

Steve Zara's Avatar Comment 5 by Steve Zara

Comment 3 by Jos Gibbons

Is supersymmetry a necessary prediction of String Theory?

Mon, 29 Aug 2011 21:22:43 UTC | #865318

Vitalic's Avatar Comment 6 by Vitalic

isn't supersymmetry tied into the current cosmological understanding of how the big bang was initiated, i know it's more to do with quantum fluctuations but afaik supersymmetry made possible the potential for matter to pop into existence from essentially nothing, but im wondering if that interpretation is still viable

Mon, 29 Aug 2011 21:39:15 UTC | #865324

Daniel Williams's Avatar Comment 7 by Daniel Williams

Bad day for Supersymmetry.

Great day for science.

Still a win for mankind.

Any one else think the LHC is a really cool piece of technology. Personally I think its up there with hubble (when it was new not that its no longer cool mind you) on the cool and cutting edge list.

Mon, 29 Aug 2011 22:15:49 UTC | #865334

FrogGenes's Avatar Comment 8 by FrogGenes

Perhaps the companion particle masses are much greater than anticipated. Wasn't this on of the concerns?

Mon, 29 Aug 2011 22:32:30 UTC | #865338

plasma-engineer's Avatar Comment 9 by plasma-engineer

Keeping theoreticians on their toes is the day job of the experimentalists! I agree with Daniel Williams - its a great day for science (even if this is 'trial by BBC' rather than 'real' science).

Mon, 29 Aug 2011 23:27:43 UTC | #865352

canadian_right's Avatar Comment 10 by canadian_right

http://en.wikipedia.org/wiki/Supersymmetry see http://everything.explained.at/Supersymmetry/

It fills some gaps in the Standard Model, and reduces the need for "fine tuning". It might help explain where some of the dark matter is too.

If it is true it is a more elegant explanation to some issues in the Standard Model than other theories.

Mon, 29 Aug 2011 23:30:34 UTC | #865354

Schrodinger's Cat's Avatar Comment 11 by Schrodinger's Cat

It's fascinating to see an example where nature doesn't follow the supposedly simple and elegant mathematics of the theoreticians. If the Higgs Boson also fails to show up....there's going to have to be some major rethinking.

Tue, 30 Aug 2011 01:37:23 UTC | #865394

Jos Gibbons's Avatar Comment 12 by Jos Gibbons

Comment #865318 by Steve Zara

Supersymmetry is actually a lot less esoteric than string theory, as it is introduced to prevent quadratic divergences in the interactions of the Higgs field, so was motivated from much simpler problems with the standard model than the currently intractable question of what it takes to quantise gravity. As it happens there are several versions of string theory of which not all are supersymmetric, but string theorists have largely given up on non-supersymmetric string theory, since it doesn't seem possible to make it compatible with the existence of fermions. Hence the modern "superstring" theories that are supersymmetric. I suppose you could say yes, supersymmetry is needed nowadays to make string theory "go". Ironically, one of the challenges is working out how to subsequently break supersymmetry, i.e. make it invisible at the low energies at which it has previously been invisible. They've had some ideas on that, so I'm not saying it's an unanswered challenge, but it certainly needed to be answered.

Comment #865324 by Vitalic

No; I'm not sure how you got that impression. You're probably mixing up supersymmetry (which says every boson species has a fermion partner species and vice versa) with the largely symmetric - and slightly asymmetric - relation between matter and antimatter. Actually, such a small asymmetry isn't needed to cause the Big Bang, but to yield the observed modern preponderance of matter in a largely antimatter-free universe. It requires, specifically, violations of the C & CP symmetries (which are fancy, more specific ways of saying matter and antimatter aren't perfect mirror images of each other). This is one of the three Sakarov conditions required for a symmetric Big Bang to give our modern asymmetric universe, together with a lack of thermal equilibrium at the time of the Big Bang and the violation of baryon number conservation (the total baryon number B and lepton number L are conserved in most interactions in the Standard Model, but attempts to move beyond it conserve B - L while making processes that change B and L together not as difficult as hitherto thought, allowing us to go from a B = L = 0 universe in the past to a large-B, large-L, presuambly B=L universe today).

Comment #865338 by FrogGenes

Yes; "they're heavier" is an implication of one of the "supersymmetry may be true but not in the simple way refuted here" suggestions.

Comment #865394 by Schrodinger's Cat

Indeed; that's how people felt when they found the aforementioned matter-antimatter asymmetries! Follow the links I gave for more information on that. Richard Feynman, in his Symmetry in Physical Laws (Chapter 2 of Six Not-So-Easy Pieces), discussed both the apparently perfect and the provably imperfect symmetries of the universe, and he makes the incongruity between the two fascinating (as if it isn't already).

Tue, 30 Aug 2011 06:22:06 UTC | #865457

DavidMcC's Avatar Comment 13 by DavidMcC

Comment 12 by Jos Gibbons

Richard Feynman, in his Symmetry in Physical Laws (Chapter 2 of Six Not-So-Easy Pieces), discussed both the apparently perfect and the provably imperfect symmetries of the universe, and he makes the incongruity between the two fascinating (as if it isn't already).

It's the "provably imperfect symmetries" that are the biggest issue with the standard model, not lack of supersymmetry, AFAIAC. To me, even the slight asymmetry that lead to a net amount of baryonic matter in the universe implies that our "Big Bang" was not from nothing, but from a prior (and much bigger) universe, even if that universe banged only a "bat of an eyelid" before producing this one, among others.

Tue, 30 Aug 2011 08:34:58 UTC | #865474

thebaldgit's Avatar Comment 14 by thebaldgit

Lets wait and see what the outcome of this is, but it is a reminder that the work of the LHC was always going to be about not just confirming all theories but also offering up new questions.

Tue, 30 Aug 2011 09:19:05 UTC | #865486

aquilacane's Avatar Comment 15 by aquilacane

Ugly facts killing less than beautiful theories. I never did see the extreme beauty of supersymmetry, but I am a mediocre mathematician!

How are facts ugly?

The honesty and commitment to truth displayed by Lykken is wonderful to see.

It should be without question, if he is looking for facts. If he is not looking for facts, then he would be wasting a lot of money.

Tue, 30 Aug 2011 13:24:43 UTC | #865541

Vicktor's Avatar Comment 16 by Vicktor

All this talk about nature being "beautiful" and theories also having to be "beautiful" is just providing ammo for religious nuts. I've said it before and I'll say it again: Scientists, please emphasize some of the flaws of nature! I'd really like to know or I might just have to drop to my knees and start worshipping some god five times a day.

Tue, 30 Aug 2011 13:44:00 UTC | #865547

DavidMcC's Avatar Comment 17 by DavidMcC

Comment 16 by Vicktor :

All this talk about nature being "beautiful" and theories also having to be "beautiful" is just providing ammo for religious nuts. I've said it before and I'll say it again: Scientists, please emphasize some of the flaws of nature! I'd really like to know or I might just have to drop to my knees and start worshipping some god five times a day.

If "beautiful" means simple, then it helps for physics to be "beautiful". On the other hand, complex, interacting system are inevitably complicated and "messy" in their details, as is the case with ecosystems (and, I would argue, universes!). Having said that, the only "gods" you would have to "worship" as a consequence of "perfect" laws would be the laws themselves, since they don't need a sky-fairy to create them.

Tue, 30 Aug 2011 13:57:34 UTC | #865551

Vicktor's Avatar Comment 18 by Vicktor

Comment 17 by DavidMcC

Still, I think scientists are overemphasizing the "beauty" of nature; not just in physics but also biology etc. They must realize that to most people it comes off as evidence of a designer. Does nature have no flaws? Surely there must be some. If not in physics then biology perhaps? Why do we hardly ever see scientists pointing them out and explaining how we could improve upon them? Now that would come off to most people as evidence that the "designer" isn't perfect.

I remember one time a Muslim kept telling me how incredibly beautiful the fish in my aquarium are, and how they looked like someone had "painted" them with colors. I pointed out that not all fish are beautiful (e.g. anglerfish) and that got him thinking for a while before just remaining silent about the matter.

I can only imagine one day how it might sound to theists when physicists can actually demonstrate a better way to build a universe than our own. Unless, of course, our universe is the most perfect one conceivable (highly unlikely in my view).

Tue, 30 Aug 2011 15:01:24 UTC | #865569

Alan4discussion's Avatar Comment 19 by Alan4discussion

I can only imagine one day how it might sound to theists when physicists can actually demonstrate a better way to build a universe than our own. Unless, of course, our universe is the most perfect one conceivable (highly unlikely in my view).

"Better" and "perfect", would imply a purpose, and purpose is a purely human objective. Galaxies, stars, planets and moons have no purpose! They just work according to the laws of science.

Tue, 30 Aug 2011 15:10:42 UTC | #865572

Vicktor's Avatar Comment 20 by Vicktor

Comment 19 by Alan4discussion

But is our universe flawed in any way? And do we know how it could be improved? Now this is the sort of thing I wish science documentaries would talk about. I know everyone gets a kick out of being the "stuff of stars" but do stars really need to "die" in a universe?

Tue, 30 Aug 2011 15:15:25 UTC | #865575

DavidMcC's Avatar Comment 21 by DavidMcC

Comment 20 by Vicktor

But is our universe flawed in any way? And do we know how it could be improved? Now this is the sort of thing I wish science documentaries would talk about.

It certainly is. As someone pointed out a while back, nearly all of the universe is wasted if there was the intent of putting mankind in it (plus supporters, like edible things, and pretty things).

Wed, 31 Aug 2011 10:43:04 UTC | #865825

Alex, adv. diab.'s Avatar Comment 22 by Alex, adv. diab.

Comment 5 by Steve Zara :

Is supersymmetry a necessary prediction of String Theory?

Hi Steve,

While the superstring has supersymmetry built into it (hence the name) and is inconsistent without it, it is not automatic that the symmetry is present in our spacetime and survives while we go from 9+1 to 3+1 dimensions by making 6 of them small. It was more or less assumed in the past because the models become mathematically most intractable if supersymmetry does not prevail to energies significantly below the Planck scale, and because of the terrible higgs finetuning problem, which really shows up badly if one is in the business of constructing a full theory of the planck scale. The unfortunate thing (or fortunate, depending on your taste) is that in this respect, supersymmetry is still possible simply at a somewhat higher scale not quite reachable by the LHC. Not finding a higgs boson, or finding a very heavy one, would probably be the most significant blow to supersymmetry that the LHC can deliver (beyond not discovering it directly of course). A Higgs boson around 140 GeV and no sign of supersymmetry at the LHC is still well compatible with supersymmetric stuff at a scale beyond LHC reach. A rather unsatisfactory situation.

Wed, 31 Aug 2011 14:57:00 UTC | #865902

Steve Zara's Avatar Comment 23 by Steve Zara

comment 22 by Alex, adv. diab.

Thank you for your detailed and informative reply.

Wed, 31 Aug 2011 15:24:46 UTC | #865914

DavidMcC's Avatar Comment 24 by DavidMcC

Comment 22 by Alex, adv. diab.

While the superstring has supersymmetry built into it (hence the name) and is inconsistent without it, it is not automatic that the symmetry is present in our spacetime and survives while we go from 9+1 to 3+1 dimensions by making 6 of them small.

And how, may I ask, is a Big Bang supposed to achieve the impressive feat of "shrink the dimensions"?

Thu, 01 Sep 2011 08:37:11 UTC | #866225

Alex, adv. diab.'s Avatar Comment 25 by Alex, adv. diab.

Comment 24 by DavidMcC :

Comment 22 by Alex, adv. diab.

While the superstring has supersymmetry built into it (hence the name) and is inconsistent without it, it is not automatic that the symmetry is present in our spacetime and survives while we go from 9+1 to 3+1 dimensions by making 6 of them small.

And how, may I ask, is a Big Bang supposed to achieve the impressive feat of "shrink the dimensions"?

You make it sound like you honestly think that no-one has ever thought about that. The opposite is the case of course, but it still is a very difficult thing. If you want to find a realistic string scenario taking everything into account, the components of the metric tensor which determine the size of the internal six-dimensional space must obtain a potential which stabilizes them towards small values, for example by having some branes of sorts wrapped up in it, while the four other metric components get blown up by the FLRW dynamics. That is very difficult, especially when you try to have the standard model come out at the same time.

Thu, 01 Sep 2011 10:19:22 UTC | #866245

DavidMcC's Avatar Comment 26 by DavidMcC

Comment 25 by Alex, adv. diab.

You make it sound like you honestly think that no-one has ever thought about that.

I never said that no-one has thought about it, but I have never seen a satisfactory answer to it.

That is very difficult, especially when you try to have the standard model come out at the same time.

Have you ever considered that this might be a mathematical solution looking for a problem? (The snag being that the maths is only addressing ONE issue in cosmology. It is the mathematical tail wagging the dog of physics.

Thu, 01 Sep 2011 10:42:15 UTC | #866249

Alex, adv. diab.'s Avatar Comment 27 by Alex, adv. diab.

Comment 26 by DavidMcC :

Comment 25 by Alex, adv. diab.

You make it sound like you honestly think that no-one has ever thought about that.

I never said that no-one has thought about it, but I have never seen a satisfactory answer to it.

That is very difficult, especially when you try to have the standard model come out at the same time.

Have you ever considered that this might be a mathematical solution looking for a problem? (The snag being that the maths is only addressing ONE issue in cosmology. It is the mathematical tail wagging the dog of physics.

Sorry I don't understand what you mean

Thu, 01 Sep 2011 10:45:35 UTC | #866250

DavidMcC's Avatar Comment 28 by DavidMcC

I mean that the kind of mathematical spaces proposed in string theory are designed to solve some problems in cosmology, but not all of them. It is better to derive the maths from a theory of quantum gravity, than to think up arbitrary mathematical objects that seem to provide a space for the particles of particle physics. Of course, it might not be possible to do that, but anything else is just a guess, a shot in the dark, moastly doomed, unless it is recognised that gravity is but part of space, so that quantizing gravity means quantizing space.

Thu, 01 Sep 2011 15:17:04 UTC | #866351

Alex, adv. diab.'s Avatar Comment 29 by Alex, adv. diab.

String Theory is a theory of quantum gravity, is it not?

unless it is recognised that gravity is but part of space, so that quantizing gravity means quantizing space.

Can you be a little less nebulous about what you are going for? "quantizing gravity means quantizing space", I think everyone would agree. Do you object to the use of "classical" objects like branes, or classical geometries like manifolds, in the theory?

Mon, 05 Sep 2011 11:25:09 UTC | #867399

DavidMcC's Avatar Comment 30 by DavidMcC

Comment 29 by Alex, adv. diab.

Do you object to the use of "classical" objects like branes, or classical geometries like manifolds, in the theory?

Yes, because they seem to be avoiding space quantization. As I understand it the "rolled-up" dimensions are only proposed to be rolled up in the first place because they are assumed to be of the same nature as the 3 dimensions we perceive, and these are taken in most string theories to be continua. AFAIK, only loop quantum gravity (Smolin) and spin foam (Ashtekar) explicitly quantize space. Maybe there are other versions of string theory, and one of them was even used to predict a multiverse (the "bubble" theory of Bryan Greene), but I think they fail on most observational aspects of cosmology, for reasons I went into in various other multiverse-related threads. Perhaps you didn't notice them?

Mon, 05 Sep 2011 11:52:31 UTC | #867409