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jacen
Austria3644 Posts
but after that .. i can't really see how you can deduct a 6th dimension out of it, as a 5th would already cover all possible timelines and to get a 6th dimension you would have to find something other than time to continue your journey. i think you could introduce differnt starting conditions here, but with different starting conditions, things like time and space become irellevant, so i can't see how they can "build up" on our established system. | ||
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jacen
Austria3644 Posts
do you think this whole string/m theory issue can be resolved with the new cern cyclotron? will it be able to pack enough energy to give us not only even more particles, but what and how they are? /edit: and yeah. i would very much like to see all this mathematical talent in nero nets, where i still think it really belongs. T_T | ||
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jacen
Austria3644 Posts
On December 08 2006 23:26 DTDominion wrote: Group Think and the Intellectual Elite Rather than bitch because it's written by Osron Scott Card, a Science Fiction author, acctually read it, as it is damned interesting, as is his entire column, even though I don't always agree with him. you know ... feynman was ALWAYS saying that. now that he is dead 20 years it seems people forgot how to work just after he died ... interesting. | ||
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Cascade
Australia5405 Posts
On December 10 2006 13:17 jacen wrote: @ cascade: do you think this whole string/m theory issue can be resolved with the new cern cyclotron? will it be able to pack enough energy to give us not only even more particles, but what and how they are? /edit: and yeah. i would very much like to see all this mathematical talent in nero nets, where i still think it really belongs. T_T Common, we have to spread to word, no? I'll take it from the begining so as many as possible can understand.  [img]http://www.phys.ufl.edu/~matchev/LHCJC/cern-lhc.jpg[/img] LHC (large hadron collider) is a huge ring of magnets, 27 kilometers around, that accelerates protons around very fast, and antiprotons around in the other direction. These two beams are made to collide at a few selected points in the ring around which they have placed detectors to see what comes out. It will go online next year, and start giving data in about a year. What is new with the LHC is that it collides the particles at an higher energy than has been done before, so heavier particles can be created in the collisions. Mass is just another form of energy. Up to now we have looked for particles of a mass up to around 100GeV (100 Giga electron Volt, or the energy an electron gains when accelerated by an electric field of 100 000 000 000 Volt), but with LHC we can find particles with a mass up to around 1000GeV (or 1 TeV). So the new particles we will find are the particles with a mass between 100GeV and 1TeV. We expect to find the Higgs particle at around 150 GeV. The Higgs is not very connected to string theory, so I will not go into this. We also expect to find supersymmetric (SUSY) particles. We expect the supersymmtric particles to exist by some reasons not connected to strings. (For example the running coupling constants will intesect much nicer in a grand unification theory if we have SUSYs...) But if we want superstrings we will need supersymmetry. In fact, the "super" of superstrings is for supersymmetry. So if we do not find SUSYs, that is a sign that we maybe do not have supersymmetry, which also implies that we do not have superstrings. I am not sure on exactly how strong sign though. We could imagine that by some reason all the SUSY are at an even energies (above 1TeV), or maybe that we can not detect them properly, or the maybe will not be created in proton-antiproton collisions... But it would defenitely be a sign that we have no SUSY, I'm sure! So finding SUSY will in no way prove superstring theory, but it will be a sign that we may be looking in more or less the right direction. Not finding SUSYs will however be a sign that the direction might be all wrong, and that we should start looking even more for alternate solutions. To actually create isolated strings we would need to go to energies of around 10^13 TeV. For that we would need an accelerator the size of the entire solar system. Which will be hard to do with todays international particle physics economy. We hope to find other more subtle means to confirm/disprove superstrings. Maybe cosmlogy may be the answer? Who knows? | ||
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jacen
Austria3644 Posts
On December 10 2006 14:06 Cascade wrote: We expect to find the Higgs particle at around 150 GeV. The Higgs is not very connected to string theory, so I will not go into this. see ... ordinary people don't know how "heavy" higgs particles are expected to be nor how much energy currently used cyclotrons are using. thats what i was asking :> thx higgs ... isn't higgs a graviton? or somewhat related to it? On December 10 2006 14:06 Cascade wrote: We also expect to find supersymmetric (SUSY) particles. We expect the supersymmtric particles to exist by some reasons not connected to strings. (For example the running coupling constants will intesect much nicer in a grand unification theory if we have SUSYs...) But if we want superstrings we will need supersymmetry. In fact, the "super" of superstrings is for supersymmetry. So if we do not find SUSYs, that is a sign that we maybe do not have supersymmetry, which also implies that we do not have superstrings. I am not sure on exactly how strong sign though. We could imagine that by some reason all the SUSY are at an even energies (above 1TeV), or maybe that we can not detect them properly, or the maybe will not be created in proton-antiproton collisions... But it would defenitely be a sign that we have no SUSY, I'm sure! wait ... so not finding SUSY with the new lhc might also mean that they don't appear until over 1TeV? whats the reason for making the lhc only limited to 1TeV and not waiting another 10 years to be able to make a bigger collider with ... lets say 5TeV and be sure? can you clarify this? sure it has to do with economics, but it sounds a little wierd you know ... knowing i build a device that might not be strong enough to detect what i am REALLY looking for. | ||
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Konni
Germany3044 Posts
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Clutch3
United States1344 Posts
On December 10 2006 05:20 HnR)hT wrote: Well, I think the suggestion that string theorists purposely obfuscate and create the theory to be untestable amounts to slander. If this were the case in such a highly visible field, it would have been exposed a long, long time ago. The notion that string theory will turn out to be a complete disaster - nothing but a distraction - is not a new one, and there are plenty of smart young people looking for glory to go around to produce competing alternatives. It's just that most come to the conclusion that string theory really is by far the most promising direction for theoretical physics today. Furthermore, practicing string theorists are extremely brilliant people and many of them routinely make meaningful contributions to other areas of physics. It may be unfortunate that there are far more students who want to go into string theory than there ought to be, but maybe that's the fault of physics educators who are concerned only with research and fail to be inspiring whatsoever. And anyway, what are Card's qualifications to comment on this matter? Yes, I agree that purposely making the theory untestable is probably taking it too far. But I'm glad someone's talking about the field. Perhaps Card doesn't have the qualifications you'd like, but if you're requiring everyone who comments about the validity of string theory to have a strong background in string theory, then in some sense you're biasing the discussion. Anyone who's spent a good deal of time on string theory (and it certainly requires a large investment of time), will most likely not agree that the whole field might be highly suspect. And yes, the fact that lots of people want to do string theory isn't really the fault of string theorists, but neither do I think it's the fault of too heavy an emphasis on research. (I do agree that the emphasis on research over teaching is really a terrible problem for physics; this is one of my biggest issues with academia.) I know there's too many grad students at Brown and other places who want to do high-energy theory, and I think it's part how the curriculum is biased towards paper-and-pencil work, and partly how overexposed string theory is in general. To expand on the latter reason, it seems to me there's something about string theory that makes it perfect for writing books and pontificating. The possible reasons I can come up with are: 1. String theorists have more time to consider the elegance of their theory, because (as I mentioned) the absence of experimental checks on the theory leaves much more room for politics and egos to drive the field. As a result, it's much likelier that the sexiest, most elegant theories are the ones which are adopted. And those are tailor-made for consumption by the mass market audience. In contrast, the physics I know about is harder to summarize by a set of equations, and it's got a lot more "ifs" and "buts", which makes for bad pop science reading. This is almost always the case where you're trying to understand the behavior of 10^18 atoms (condensed matter physics) than of just a few particles (theoretical particle physics). 2. Because string theory has no immediate commercial impact, the money supporting it comes much more heavily from government funding. And the competition for that funding is intense. So people doing string theory have to learn to package and sell their ideas much better than those in, say, semiconductor physics. This also translates into more, and better, self-promotion. | ||
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Clutch3
United States1344 Posts
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jacen
Austria3644 Posts
On December 10 2006 14:38 Clutch3 wrote: This also translates into more, and better, self-promotion. this bothers me. scientists should think about their field. not about how to present that field. | ||
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Cascade
Australia5405 Posts
I'm getting a bit mathematical now: A normal mass term (in the lagrangian, that is THE equation describing the theory...) is not invariant under a gauge transformation. And the entire theory is built upon being gauge invariant. To compensate, we need another particle that transforms in exactly the opposite way to cancel out the assymetry from the mass terms. This particle is the Higgs particle. And particle physics are in quite big trouble if we do not find it.  And it will (imo) be the greatest success in the history of particle physics if it turns out that we predicted correctly. So check the newspappers in late 2007.  And for the record: A graviton is the particle mediating the gravitational force. It is massless, but still not detected due to it's VERY weak coupling to everything. It does however "bend reality" more or less in the way black holes and the like does in movies and cartoons. They try to measure this smal distortion by putting up mirrors and have light bounce between them and measure the time it takes to bounce back and forth. If a big distortion enough passes by, then we can measure that the distance between the mirrors changes oh so little. they have to measure the distance with an accuracy of just a fraction the size of an atom, but they do. This experiment is in Pisa Italy, iirc.Yes, If we do not find SUSY they MIGHT still be somewhere over 1TeV. But I think (not sure here...) that we got quite strong arguments for why at least some should be below 1TeV. It is like IF they would be heavier, then they would have interfered in other reactions which we would have noticied. And yes, economy is the reason we do not build a bigger accelerator. 27km is enough for now imo. ffs, get people in africa non-piosonous water first...Allready a LOT of countries have teamed up to build the LHC, so we ARE pushing the limits for what the economy can take. going up a factor 10 in energy is actually a lot. Imagine that they first planned to build a 300GeV accelerator, and then reconsidered: "Why build an 300GeV, when we could gather up some more money and build a 1TeV instead?". Would that make you happier? And again for the record. The center of mass energy of the proton and antiproton is 14TeV, but since only one of the quarks in each (anti)proton collides at a time, only a fraction of the total proton energy will be used, so the effectiv energy will be about 1TeV. | ||
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jacen
Austria3644 Posts
On December 10 2006 14:58 Cascade wrote: No, Higgs isn't a graviton. The Higgs is needed to give mass to the other particles without breaking the oh so precious gauge symmetry. I'm getting a bit mathematical now: A normal mass term (in the lagrangian, that is THE equation describing the theory...) is not invariant under a gauge transformation. And the entire theory is built upon being gauge invariant. To compensate, we need another particle that transforms in exactly the opposite way to cancel out the assymetry from the mass terms. This particle is the Higgs particle.see, thats the reason why i read physics literature for fun and you deal with this for a living On December 10 2006 14:58 Cascade wrote: Imagine that they first planned to build a 300GeV accelerator, and then reconsidered: "Why build an 300GeV, when we could gather up some more money and build a 1TeV instead?". Would that make you happier? i just mean't: "why build a new collider when it may not even bring new deeper insight?" i know these things cost a little money (well ... depends on your financial scale i guess ), but your mention of SUSY might beeing out of reach with the new collider gave me a downer. but if you say that the new collider will most likely proof or disproof SUSY either way (by either showing or not showing up) it seems reasonable to build it now. | ||
Smurg
Australia3818 Posts
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Cascade
Australia5405 Posts
But as I said: If we do not see them, it is a sign that they do not exist. I personally dont know exactly how strong sign, but I've gotten the impression that it would be fairly strong. And sorry about the maths. | ||
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jacen
Austria3644 Posts
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Asta
Germany3491 Posts
On December 10 2006 14:58 Cascade wrote: It is like IF they would be heavier, then they would have interfered in other reactions which we would have noticied. I know almost nothing about the subject but afaik at some weight it will become unlikely that such heavy particles have been created naturally, right? Theoretically there could be particles weighing as much as the Planck mass (≈ 1.2209 × 10^19 GeV/c2 according to wikipedia) but they will never be produced by any natural event. | ||
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SolaR-
United States2685 Posts
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jacen
Austria3644 Posts
On December 10 2006 15:29 Asta wrote: I know almost nothing about the subject but afaik at some weight it will become unlikely that such heavy particles have been created naturally, right? Theoretically there could be particles weighing as much as the Planck mass (≈ 1.2209 × 10^19 GeV/c2 according to wikipedia) but they will never be produced by any natural event. isn't this a non-issue? we wan't to know how the complete system of how mass is "generated" and how this connects to gravity and timespace works ... and not only how it works in most cases. right? | ||
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Cascade
Australia5405 Posts
On December 10 2006 15:29 Asta wrote: I know almost nothing about the subject but afaik at some weight it will become unlikely that such heavy particles have been created naturally, right? Theoretically there could be particles weighing as much as the Planck mass (≈ 1.2209 × 10^19 GeV/c2 according to wikipedia) but they will never be produced by any natural event. Well, it depends on what you mean by naturally. In normal everyday life for you and me, we will not be dealing with energies close to creating any particles at all. In the core of the sun there are energies of the scale a few MeV (1000MeV = 1GeV), which is enough to created a few of the lightest particles, for example electrons. LHC will be at 1TeV which will create quite a lot of particles, even if we find nothing new. If you go back in time to the big bang we will arrive at high energies enough to create anything. Including for example elephants. Heavy particled would probably not be stable though, in the sence that they would decay into other light particles, if that is what you mean? So we do not expect to see them as even if they were created, they would have decayed by now. We have some ideas of what particles may exist up to the planck energy (planck mass, w/e, same shit). For example we may find SUSYs and many belive that we will find a set of particles at around 10^15GeV. Above that energy, quantum gravity will come into play seriously, and then we have no idea at all what may exist. String theory is our best guess for energies above that, but as we all know by now: string theory is not experimentally verified so... Don't know if I answered your question. | ||
Bill307
Canada9103 Posts
I did some reading on Wikipedia and the reason String Theory predicts the existence of 10 dimensions (or 11 for M-Theory) is because that is the only way a photon can have no mass. Since String Theory is just a theory and far from fact, there might not be 10 dimensions at all. There might be only 4. But I wouldn't dismiss higher dimensions as "bullshit" just because we can't perceive them. For example, in medieval times europeans believed that the sun revolved around the earth partly because they could not perceive the motion of the earth. Nowadays we know better, but back then people would have called bullshit: "If the earth is moving then why don't we fly off?" | ||
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Bill307
Canada9103 Posts
On December 10 2006 14:06 Cascade wrote: We also expect to find supersymmetric (SUSY) particles. We expect the supersymmtric particles to exist by some reasons not connected to strings. (For example the running coupling constants will intesect much nicer in a grand unification theory if we have SUSYs...) But if we want superstrings we will need supersymmetry. In fact, the "super" of superstrings is for supersymmetry. So if we do not find SUSYs, that is a sign that we maybe do not have supersymmetry, which also implies that we do not have superstrings. I am not sure on exactly how strong sign though. We could imagine that by some reason all the SUSY are at an even energies (above 1TeV), or maybe that we can not detect them properly, or the maybe will not be created in proton-antiproton collisions... But it would defenitely be a sign that we have no SUSY, I'm sure! So finding SUSY will in no way prove superstring theory, but it will be a sign that we may be looking in more or less the right direction. Not finding SUSYs will however be a sign that the direction might be all wrong, and that we should start looking even more for alternate solutions. The article in Wikipedia leans more in the direction of "if supersymmetry isn't found then it's not a problem": For example, while supersymmetry is now seen as a vital ingredient of string theory, supersymmetric models with no obvious connection to string theory are also studied. Therefore, if supersymmetry were detected at the Large Hadron Collider it would not be seen as a direct confirmation of the theory. More importantly, if supersymmetry were not detected, there are vacua in string theory in which supersymmetry would only be seen at much higher energies, so its absence would not falsify string theory. http://en.wikipedia.org/wiki/String_theory#Problems_and_controversy | ||
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