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Physicists say universe evolution favored three and seven dimensions
Physicists who work with a concept called string theory envision our universe as an eerie place with at least nine spatial dimensions, six of them hidden from us, perhaps curled up in some way so they are undetectable. The big question is why we experience the universe in only three spatial dimensions instead of four, or six, or nine.
Two theoretical researchers from the University of Washington and Harvard University think they might have found the answer. They believe the way our universe started and then diluted as it expanded – what they call the relaxation principle – favored formation of three- and seven-dimensional realities. The one we happen to experience has three dimensions.
"That's what comes out when you do the math," said Andreas Karch, a University of Washington assistant professor of physics and lead author of a new paper that details the theory.
Karch and his collaborator, Lisa Randall, a physics professor at Harvard, set out to model how the universe was arranged right after it began in the big bang, and then watch how the cosmos evolved as it expanded and diluted. The only assumptions were that it started with a generally smooth configuration, with numerous structures – called membranes, or "branes" – that existed in various spatial dimensions from one to nine, all of them large and none curled up.
The researchers allowed the cosmos to evolve naturally, without making any additional assumptions. They found that as the branes diluted, the ones that survived displayed three dimensions or seven dimensions. In our universe, everything we see and experience is stuck to one of those branes, and for it to result in a three-dimensional universe the brane must be three-dimensional.
Other realities, either three- or seven-dimensional, could be hidden from our perception in the universe, Karch said.
"There are regions that feel 3D. There are regions that feel 5D. There are regions that feel 9D. These extra dimensions are infinitely large. We just happen to be in a place that feels 3D to us," he said.
In our world, forces such as electromagnetism only recognize three dimensions and behave according to our laws of physics, their strength diminishing with distance. Gravity, however, cuts across all dimensions, even those not recognized in our world, Karch and Randall say. But they theorize that the force of gravity is localized and, with seven branes, gravity would diminish far more quickly with distance than it does in our three-dimensional world.
"We know there are people in our three-brane existence. In this case we will assume there are people somewhere nearby in a seven-brane existence. The people in the three-brane would have a far more interesting world, with more complex structures," Karch said. With gravity diminishing rapidly with distance, a seven-dimensional existence would not have planets with stable orbits around their sun, Karch said.
"I am not precisely sure what a universe with such a short-range gravity would look like, mostly because it is always difficult to imagine how life would develop under completely different circumstances," he said. "But in any case, planetary systems as we know them wouldn't form. The possibility of stable orbits is what makes the three-dimensional world more interesting."
Karch and Randall detail their work in the October edition of Physical Review Letters, published by the American Physical Society. The research was supported by grants from the U.S. Department of Energy and the National Science Foundation.
Karch said they hope the work will spark extensive scientific exploration of many other questions involving string theory, extra dimensions and the evolution of the cosmos.
From University of Washington
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Anothr question that came to mind..
If you had ideal cirumstances where you had a shuttle in space, and no other forces would effect th following experiment, would gas consumption follow pythagorean theorum? If you could burn exactly three thousand gallons going forward, and exactly four thousand gallons going up. Would you burn exactly 5,000 gallons finishing the hypotaneuse of the the triangle? Or is it not quite that efficient/accurate? What is the tolerance range of that test?
My take on branes..
I bet when most people think of branes, they picture a dimensional sandwich, or dimensional strata because thats what most illustrations seem to depict.
Probably because thats the easiest way to depect it.
But I think that this is an over simplification. Picture basically a lucite cube. In this cube there are floating pennies that are ultra thin. Now imagine that as you look at each side of the cube, any time you look foward, all the pennies appear facing you, and the color green. Now you look at the top, and the penny you were looking at has disappeared, but nearly in the same spot, facing up at you is the face of a red penny. If you look at the front of the cube again, but tip it down just slightly to see the depth of the pennies, the front is still green, but now you can see blue edges extending backward and any penny you view continually will also be fully blue. If you focused on the third penny back initially, it would have a green front, but every penny in front of it, and the back of the penny on to infinity would be blue.
I picture each penny as the position of the smallest measurable matter in existance (regardless of our ability to measure it or not). This smallest point of matter would look to us as a single dot. But it is not. It is 129601 dots. A central dot, and a dot for every 3d (or 4d if you count diagonal as a dimension) position 1 degree off of center. Although each of the dots have the illusion of occupying the same space, they in fact don't exactly.. They are all out of phase with each other. We images x and y co-ordinates as intersecting, but that is our brains simplifying the illusion. In point of fact, both are seperate dimensions and never actually meet. Think of a small light bulb traveling through a colored glass tube. If the tubes overlap at any point, the light will hit the point of the overlap and appear to be in both tubes. But it is in fact, only in one tube. Either the front tube or the back tube. Either way, the light appears in the same position, but is not actually in the same position for both tubes.
A more direct way to picture this is to say that both tubes DO actually merge and intersect..BUT if you were in one of the tubes, and your perceptions were limited to that tube..anything in the tube would be visible to you and solid. But you could walk through the intersecting tube and never even know it..Even if your perceptions allowed you to see what was in the tube, it would be out of phase with you, you'd try to grab something from that tube, it would be like nothing was actually there.. or it would be like trying to grab a ghost.
The reason the math still works and movement still works is a variation on the Heisenberg Uncertainty Principle. Basically, we can never know exactly where something is in relation to something else, but we can give an educated and accurate enough guess to be close to being right most of the time.
Now, if you agree with everything or most of what I've said to this point, then adopting diagonal as a 4th dimension is not that far of a stretch. Because if you always had to go on the x and y axes to move diagonally, EVERY diagonal line should look like a step latter pattern at the smallest possible size of matter. In order to follow the shortest distance between two points is a straight line rule, diagonal has to actually exist as a seperate dimension. Forget that we can make it work visually and mathematically. To me, that is just a very logically told lie of omission. I believe the universe tries to be as efficient in running as possible, and as such, I believe each dimesion was meant to be a true representation of a straight line going in a specific direction. I further believe that in time, if we learn true diagonal propulsion, we will learn that in right triangles, the actual value of a hypotenuese will become less important than the conceptual value. In other words, rather than thinking of the solution of pythagoreans theorum as a^2+b^2=c^2.. a=1, b=1 c= square root of two, it will be a=1, b=1, c=1 because the actual translation will be that you traversed the distance of the width of the cube and height of the cube in order to get to the opposite corner of the cube. The value of c might be factually variable, but it won't matter, because it will probably be thought of in terms of impulse.. And providing impulse to travel one over and one up allows you enough impulse to move one square..from corner to corner.
later dimensions..
I might be a laymen, and I have nothing to back my ideas up, but...
I don't agree with the idea that gravity or matter would be diminished in 5D or 7D worlds. If anything, I think that as you go to higher dimensions, its always a case of 1 step backwards 3 steps forward as far was what you can perceive there. In other words, eveything shrinks down a little in size because that dimension is technically existing at a higher "resolution" but there is so much more detail and information in that dimension, that you actually perceive the items to be bigger and much more detailed. Smoothe surfaces by 3D standards are probably rougher and uneven in higher Dimensions.. However if you were to make something smoothe in a higher dimension and then perceive it at 3D it would probably seem impossibly smoothe to the point where its details almost might seem indistint or washed out. And chances are, you'd always have the feeling that you should be seeing more to the surface, but it would be beyond your perception. You can see it, but it be hard to look at long, because you'd feel like you are looking at it with crossed eyes or as if you were looking at something your eyes couldn't quite focus on..
The same thing applies to gravity. Technically I think gravity is a solid force that exists equally throughout all of the dimensions, but I think that if you were a 3D person visiting people in a 5D world, they wouldn't feel the gravity any heavier than you feel our Earth's gravity, but to you it would seem much heavier, because you would actually be getting more detail and information of the force of the pull.. Whats more, you might even be able to tangibly feel pressure points from the gravity, and maybe even see it to an extent.. This is all of course, assuming that going more than one dimension up doesn't result in enough information that the gravity just crushes you on contact. Keep in mind that if you double both sides of the resolution of a monitor you have quadrupled the total amount of information on the screen. Each dimension might follow similar laws. And since we think of the dimensions as branes now, I can't help but think of it as a giant LCD screen with a slightly prickly surface..
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