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Is the Universe a Hall of Mirrors?
PhysicsWeb is running an article by one of the researchers who has developed the theory that the universe may be finite, rather small, and soccer-ball shaped. The question is still open; it's one theory that fits cosmic microwave data from the Wilkinson Microwave Anisotropy Probe (WMAP). Apparently testing the theory by looking in the indicated way through the WMAP data would so far be computationally prohibitive. From the article: "The Poincaré dodecahedral space can be described as the interior of a 'sphere' made from 12 slightly curved pentagons. However, there is one big difference between this shape and a football [soccer ball] because when one goes out from a pentagonal face, one immediately comes back inside the ball from the opposite face after a 36 degree rotation. Such a multiply connected space can therefore generate multiple images of the same object, such as a planet or a photon. Other such well-proportioned, spherical spaces that fit the WMAP data are the tetrahedron and the octahedron."
Personally I subscribe to Professor Hawkings theory of a donut shaped universe.
Do not try to read the dupe, thats impossible. Instead, only try to realize the truth
What truth?
There is no dupe
No, nothing has to be "containing" it. Think of it like walking on the surface of the Earth. If you look in either direction you can see pretty far and you might imagine that the Earth goes on forever. If you start walking, you will walk all the way around the Earth and end up exactly where you started. The Earth simply curves back on itself. You could walk around the Earth forever and never reach a boundary where Earth ends, but the Earth itself is still finite.
As to what this soccer ball universe could floating in, well, the question itself is probably the largest issue. We don't know the answer, but the it could very well be that there is no "outside of the soccer ball". The universe could be all that there is. There could be no "beyond" the universe or "outside" of the universe. It is hard concept to visualize, but that is pretty much true of any concept that outside of the traditional Newtonian world.
Once you leave the safe world of Newtonian physics you need to develop a superhuman ability to try and NOT visualize the universe on the grand scale of the quantum scale. Human intuition and visualizations is was built for Newtons world. Once you leave that world, it breaks down and fails to be much help.
Not a chance man. If it was, the elephants would have eaten it already.
No, that would be if it were peanut shaped.
Monkeys would eat a banana shaped universe. And there just may not be enough monkeys far enough back in time when the universe was small for them to eat it.
If anyone's looking to understand this, the book you need is "How the Universe Got Its Spots" by Janna Levine. It covers all the apparently valid but actually nonsensical questions that people have when they first hear about this (what's the universe inside then? what happens at a boundary? etc), and it explains it in such a way that you don't need a degree in topology to understand it.
If our universe resembles a video game, could it actually be a video game?
:D
That logic is fallacious, even if the observable universe is a "simulation", then this simulation runs inside a real universe, and we're at the start again figuring out what the universe is.
Plus I subscribe to another logic: if the universe is similar to a video game, then it's because as video games increase in complexity they start to approach the model of a little universe
The mistake is thinking of there being an actual boundary. You need to think of it more like the crotch on a pair of pants - imagine that each pentagon has a tube connected to it, and you run it to the other side and connect it up with the appropriate twist. Then imagine that you turned the whole thing into rubber. There is no longer a sharp edge, just a blobby series of tubes joined by a bunch of U-shaped pant crotch things. The fact that two particles that were very close to each other before they entered separate tubes has no bearing at all on how far they will be after they enter the tubes. It may have great bearing on the details of the force laws that they interact under (basically, every "mirror" particle has to be accounted for, including the infinite copies of the particle itself; this is an incredibly delicate self-action problem even for the simplest multiply connected spacetimes).
If you have noisy data and you keep analyzing it enough, you'll eventually find some bizarre model that fits it better than a more plausible model.
It's probably best not to have a firm opinion on the shape of the universe until a lot more data is in.
you know, I don't know of that many things you kick with something other than your foot.......
I'm sure the guys before Eratosthenes thought the exact same thing regarding the earth's surface.
The human mind is the product of millions of years of evolution designed to think in a Newtonian way. You are hardwired to think Newtonian. This hardware does very deep and is a fundamental piece of your core persona. Consider for a moment that if you toss a ball, a dog can jump up in the air and snatch it. This gives you an idea of how hardwired we are to think in Newtonian terms. This is an an ancient way of thinking that goes back well before we were primates, much less full blown humans.
Anyone can tell you what happens when you hit one object against another or toss one object against gravity at a certain angle. Even small children know roughly where a baseball is going to end up the second you release it from a throw despite the fact that the real calculation would take someone a few minutes to make. With quantum mechanics, you are never going to have that child like grasp of what happens when two atoms start interacting.
While we do make visual models to understand quantum mechanics, they really are only a crude ways to give our poor mammalian brain some straws to grasp at. We can visualize orbitals to some extent, but anything deeper then that kicks human intuition which has been developed to deal with a Newtonian world in the balls. You really can only truly 'understand' quantum mechanics and general relativity with math. And not just simple math, but ugly math that kids go to college for years to understand.
Without the hardwired machinery to give us answers like what we have for Newtonian physics, there is no ability to develop and "intuition" for quantum mechanics. Quantum mechanics is ugly math combined with concepts that have no Newtonian world analogy. Let the kids know that this stuff exists, but keep them in their happy Newtonian world where their hardwired physics engines can pick up the slack. Save quantum mechanics for after they know calculus.
Yes, they can, but that does not make them "hardwired" to do Newtonian physics; physics is the mathematical description of the real world, and so someone who lives in the real world and experiences it will have intuition into how physics works. If we lived and experienced in the quantum or the relativistic, we would have intuition into how that works as well. However, if you have never experienced something (even Newtonian physics), then you have no intuition about it because it is not something hardwired. Examples: on this very site a while back, there was a heated discussion about what would happen if there were a a tunnel bored completely through the Earth and you fell it in. What would happen? People disagreed. Also, Total Internal Reflection. I don't think that a dog, or a child, or anyone who hasn't taken a physics course or read about fiber optic cables would know about this. There is no intuition about it, but it is Newtonian physics. Physics is not hardwired into anybody's or anthing's brain. Our seemingly innate grasp is the ability to find patterns in the behavior of things, which is why the dog will know when to jump to catch a ball, or why the child knows where the ball will land (approximately). If we have no experience to find patterns in, we won't know our heads from our asses, metaphorically speaking.
As a consequence, you can grow intuition as you work with something. Which is why if you do enough quantum mechanical calculations, you will begin to have a sense of "what looks right," to have intuition about how quantum mechanics works. True, because we can only express quantum mechanics, our intuition in mathematical, but just like the physics student can translate the mathematical expressions of Newtonian physics into consequences in the real world (i.e. if the momentum of A is bigger than B, then they will both move mostly in the direction of A if they have an inelastic collision), the student of quantum mechanics can say "This Hamiltonian of an electron doesn't have any nodes. Then it must be in an s-orbital." Just because we are not as intimately familiar with quantum mechanics as we are with Newtonian physics because we live in the latter, not former, doesn't mean we can develop an intuition into how the former works.
It has been a nervous year, with people beginning to feel like Christian Scientists with appendicitis.
If we live inside a simulation, then, to us, that simulation *is* the universe. What lies "outside" of it can only be determined if the creators of such a simulation wanted us to do so. Is it possible for a video game character to leave a computer game and enter the real world (or at least what we consider to be the real world)? Only through the intervention of it's creators (i.e. us). The same would occur if we ourselves are constructs of a simulation.
Don't you just hate it when people reply to your signature?
I'd say it's more like asteroids, since it doesn't matter which side you leave from...
09F91102 no, 455FE104 nope, F190A1E8 uh-uh, 7A5F8A09 that's not it, C87294CE no. Ah! 452F6E403CDF10714E41DFAA257D313F.
First, think of good old Zeno's paradox (well, one of them), where you have Achilles chasing a tortoise. The tortoise has a head start. When the starting gun sounds, Achilles crosses the short distance to the tortoise's starting position quite quickly, but when he arrives he finds that the tortoise has moved on. So he crosses this short distance even more quickly, only to find that the tortoise has moved a tiny bit further. And so on ad infinitum. Zeno concluded that Achilles could not catch the tortoise, but since we can easily observe that any person can catch the tortoise, Zeno called this a paradox.
Now, Zeno's paradoxes really aren't worth that much, it turns out. However, now let's put a jet pack on the tortoise. This jet pack is constrained to never let the tortoise move as fast as Achilles can run (don't ask how), but it will perpetually bring the tortoise closer and closer to Achilles' speed. Now, Achilles runs to the tortoise's starting position, and finds the tortoise has moved on a short way. So, he then looks at the tortoise's new position, and runs to that position. The tortoise now has a new position, so Achilles runs to there. In the original scenario with constant speeds, the time it took Achilles to reach each new position was smaller, in fact greatly smaller. The times form a geometric series, which converges nicely. However, with this supercharged tortoise, Achilles finds that the times to catch up do not form a convergent series. That is, the total time for Achilles to catch the tortoise diverges, or is infinite.
Now let Achilles be a photon, and let the tortoise be a spaceship. The spaceship has an unlimited amount of fuel, and can keep up a constant acceleration for as long as the pilot likes. So, the pilot looks out his back window, and sees nothing. The photons behind him (well, the ones that started far enough away that is) can never catch him. It looks like there is a black hole following him. In fact, what with the equivalence of acceleration and gravity, from the astronaut's frame of reference, there IS a black hole following him! Of course, if he gives up trying to escape it, and just lets himself fall back into it, then he stops accelerating, the photons can catch up, and the black hole disappears.
So, the GP was wrong. But the parent isn't completely right either, unless his "unless they pass the event horizon of a black hole" was intended to include accelerational black holes like this.
My example was taken (in essence, not in text) from Nigel Calder's Einstein's Universe, an excellent book if you're bored.
SIGSEGV caught, terminating
wait... not that kind of sig.
It's less a fallacy and more "OMG I watched the Matirx, and like, it was deeeeeep, man!"
Amazing how many armchair philosophers come out of the woodwork when a movie has kung-fu and guns in it.
Endless arguments over trivial contradictions in books written by ignorant savages to explain thunder in the dark.
The book is Tau Zero, written by Poul Anderson if I recall correctly.