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Manyfold Universe Theory
Geek-from-parallel-Universe writes "In the HEP preprints database a preprint
">appeared
in which the authors propose that a world is a brane folded many times in extra sub-millimiter spatial dimensions. We see other folds only
through gravity as a dark matter because light must go around the folds. If this is true then I am waiting for Star Trek-like devices:
'portable submillimeter wormhole generator' and 'personal parallel
universe transmitter' to appear on the market. :-)"
Data: Captain, we're picking up a strange anomaly on radar
...
Picard: On screen
Data: It can't be
Picard: It is..! Another wild theory captured by the media-machine and blown out of all proportion.
Data: What's your order, sir?
Picard: Shields. Lock phasers
Picard: Mr Scott, Warp 4. Get us out of here. And avoid that trans-dimensional worm hole, damnit.
If this is true then I am waiting for Star Trek-like devices: 'portable submillimeter wormhole generator' and 'personal parallel universe transmitter' to appear on the market.
Better not start using these just yet. We wouldn't want Windows 98 to contaminate other universes. Wait 'till AFTER the antitrust thing is done.
One thing you must remember about dimensions:
:-)
A dimension is at right angles to all other dimensions. Not curled up, or anything of that sort. A small dimension (around 1 mm or what have you) is enough to hold an infinite number of 3 dimensional universes, because a 3 dimensional universe has zero size in that dimension.
Tricky shit, huh?
Anyway, this postulates that gravitons do travel along a 4th dimension (not time, thank you) to affect other universes. If that's the case, then that's probably what's on the other side of the singularity of a black hole. A different universe. Of course, I'm just making this all up as I go along, but it's still pretty interesting.
---
- Give a man a fire and he's warm for a day, but set him on fire and he's warm for the rest of his life.
Topology is very interesting. You can think of further dimension as "casting a shadow" to lower dimensions. For instance....the shadow of a sphere is 3d is a circle in 2d. The shadow of a 4dSphere is thus a 3d sphere in 3 dimensions. Quite a while ago (1996?) I read an article in a scientific journal in which a dance of the honeybee corresponded directly to a "shadow" of the Flag Manifold. The article suggested that there were interactions on the quark level that effected our 3d world, and hence the bee gets its dance.
h tml
http://www.physics.helsinki.fi/~matpitka/honey.
I read an awesome book on the field of topology but I forget the title now. What they were explaining and attempting to describe on paper no less, what really mind-expanding for me. To think...all these weird things we can't quite reconcile with each other may just be because of a greater scheme outside our perception...that we are just the shadow of an even greater and more complicated play. That when things mysteriously "disappear" and "reappear" at the quantum level, that it could possibly be because they are "shifting" in a dimension we can't percieve. A good way to think about extra dimensions is to give them names of other continuims...like "color"....e.g. This particle is at location (1,2,1,red). Very interesting stuff. I have to find that book again...amazing diagrams of 4th and xth dimensional objects.
It's 10 PM. Do you know if you're un-American?
The Theory of Sub-millimeter Extra Dimensions is a neat way of explaining what is called the "hierachy problem", mainly why the Plank scale 2*10E18GeV is so high. We have found most of the elementary particles with the number and properties of the Higgs particle(s) and possible supersymmetric partners the most reasonable "undiscovered" particles left. All these particles even the undiscovered ones stay with their mass below a few 1000GeV. So why is there a "Desert" that spans 1000000000000000GeV of the energy scale befor something happens to the particle content again? Small Extra Dimensions are an elegant way of solving this problem without introducing lots of new particles and interactions. I really like the idea because it is so simple, I distrust it partly because it can be used to give almost any kind of physics i.e. it always works and it is difficult to experimentaly test it. On the other hand this idea has been around for a couple of years now so it can't be totally crappy. I hope you remember some high school physics. You may remember that the gravitational force and the electromagnetic force both grow weaker with the inverse square of the distance ~G*r^-2 with G the constant of the relevant force. If you know Math or have done universtiy physics you know that this law is because the space is three-dimensional and this is just the way a wave dissipates in three dimensions. Now imagine that as you go to smaller and smaller distances, say between two particles, the space suddenly has more dimensions so the wave gets to dissipate at a faster rate. Since the interaction remains the same the coupling constant G must change in response. The coupling constant of gravity relates to the Plank scale so you end up changing that and voila by adding some extra dimensions the "Desert" dissapears and everybody is happy. Exept for the experimantalists since you can't verify this theory yet...
Just look at the expanding / contracting universe theory [...] after this was suggested the scientific community disregarded it and the original author retracted it.
Seems that you don't have much of a clue what "science" means.
Western science doesn't teach facts (as such), it teaches a method. The method (crudely stated) says that a bright idea gets written up, passed around a bit, and described as a "theory". No-one claims it's provably true. It's just there as a hypothetical idea, for discussion and debate. If, after some thought, an experiment is devised that can demonstrate it, then we might start to collect experimental proof that validates it. The best experiment is one that requires some outlandish and unexpected result, but a result that is predicted by this theory. If the experiment then produces that result as predicted, weird as it first sounded, then the majority of scientists start to believe in it.
If after some enormous period of time, a general concensus and a lack of contrary experimental evidence, then the theory may begin to be regarded as a "law of nature". Even then, no-one really claims that it's perfect or entirely accurate; after all Newton's Laws of Motion are demonstrably inaccurate for relativistic speeds, yet we still feel quite happy to build aircraft based on them, nor has anyone suggested they be re-phrased as "Newton's Wrong Theory of Stuff, Hey Isaac, you really like suck, man".
So where does that leave "expanding universe theory" ? Well, it leaves it just there; as a theory. What's your problem here ? No-one ever claimed it was right, just that it was one possible explanation of how things worked, that fitted what was known at the time. We look harder, we think harder, we get better ideas about it. As we've been looking at the universe for barely any time at all, from just the one pipsqueak little planet, then it's amazing we've worked out as much as we have done! Universes are complex critters and they don't come with instruction manuals -- why should we be able to work out how they operate ?
Um, it's manifold not manYfold. A manifold is another term for dimension or "membrane". E.g. Our universe is a manifold of X dimensions.
It's 10 PM. Do you know if you're un-American?
There's actually been a lot of fuss about what's called "large extra dimensions" recently. The original problem was that the energy scale associated with gravity is about 10^19 GeV (1GeV = the energy an electron would get going through a potential gap of 10^9 V = approximately the mass of a proton) while the energy scale associated with all the other forces of nature is only 10^3 GeV. This is really bad because it means that (for instance) particles would get gravitational fields surrounding them that give them masses on the order of 10^19 GeV, which would turn everything in sight into a black hole.
:) is one thing. In some of the models effective FTL travel may be possible.
This problem can be solved in a number of ways - notably supersymmetry, which causes those giant gravitational fields to cancel out. But there's one other odd problem to deal with, which are "extra dimensions." Basically string theory requires that the universe is actually 10-dimensional, and the other 6 dimensions are simply wrapped up very tightly. (Mental picture: If you wrap up a sheet of paper (which is 2-dimensional) into a very tight tube and look at it from far away, it looks 1-dimensional. Unless you're scanning it on distance scales comparable to the radius of the tube.) The problem is that you have to somehow wrap up these 6 dimensions on a really small distance scale (the length scale of gravity, about 10^-42 cm) and keep the other 4 really big. (the size of the universe) This again happens because the energy scale of gravity is big.
So about a year ago, Nima Arkani-Hamed, Savas Dimopoulos, Gia Dvali and John March-Russell had an interesting thought: We don't *know* that gravity really behaves like anything in particular at length scales below about a millimeter. (The current limit of experiment is about 0.8mm) So they noticed that the following setup gives the right answers too:
* We live in a universe with however many "extra" (small, rolled-up) dimensions, but these are rolled up with radii on the order of somewhere between 1fm (10^-15m, the size of a nucleus) to 0.1mm. (The range of sizes is because there are several different models)
* In this loosely rolled-up world, there are these 4-dimensional objects called "branes" floating around.
Then several amazing things happen. First of all, all matter particles (electrons, quarks, people) are bound to the surface of the brane and can't leave it. So are all the non-gravity force particles. (Photons, gluons, etc.) This just follows from the physical properties of branes in string theory, and it means that as far as anything but gravity is concerned, the universe is 4-dimensional and we won't see the extra dimensions.
Second, gravity completely ignores the brane (except insofar as there's matter, and therefore sources of gravity, there) and flies around freely in all of the dimensions. But because some of them are rolled up, what happens is that at long distances (bigger than the radius) all the gravity gets "squeezed" along the extra dimensions and gravity behaves like ordinary 4-dimensional gravity. At short distances, this changes -- for instance, the 1/r^2 force of gravity becomes something like 1/r^4.
But the real magic is, if the fundamental energy scale of gravity was 10^3 GeV, (the same as the scale for everything else) the distortion of gravity by the rolling up of space would make it seem like the scale was 10^19 GeV to any observer looking at distance scales bigger than the radius!
So the bonus of the Large Extra Dimensions (LED) scenario is, everything has the same energy scale, and it only seems that gravity has this high energy scale because we're looking at too long a distance. And all of the problems of a high energy scale indeed go away.
Of course, you can ask what the hell any of this has to do with reality. The thing is that all of this is consistent with all experiments to date and explains several tricky points. More importantly, it is experimentally testable; part of the testing happens in tabletop experiments (groups at Stanford and at NIST in Boulder are working on measuring gravity at distances down to about 10^-6 m) and part of it in accelerators. The final tests (thumbs up or thumbs down) will come from experiments at the LHC accelerator in Geneva, which should (knock on wood) be up to spin around 2004/5. Final results should take a few more years after the machine comes on-line.
But disclaimer: At this point this entire scenario is conjecture. People are already working out "observational experiments" to check these models -- for instance, whether these are consistent with the known spectrum of cosmic rays -- which are strong experimental constraints. But until the final experiments happen we can't be certain, one way or the other.
Also, since the original paper came out there have been several modified versions of the conjecture, which differ essentially in technical (but very important) points. The Randall-Sundrum model is especially important, and today's model looks to join the list of candidates.
So what does this mean for us? First of all, if it's right then the underlying scale of gravity is only 10^3 GeV, which is definitely accessible with the next generation (LHC) of accelerators. This means we can start to directly monkey around with the processes associated with black hole formation and the origins of the universe. Apart from completely changing physics (by making quantum gravity experiments practical) this is one of those things that creates more applications than we know what to do with. Making small black holes (and no, they wouldn't eat up the planet.
But possibly the most interesting thing is that there's no reason at all for our brane -- the one that our universe lives on -- is the only one. In fact, the most reasonable model suggests that there is some unbelievable number of branes floating out there, maybe 10^24 of them. It's not clear that the laws of physics would be the same on all of them -- e.g. the speed of light may be different, or the charge of the electron, or whatever -- but if the scenario turns out to be true, it is possible (though difficult) to communicate between two different worlds.
And for my money, that's the neatest thing of all.