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The Universe May Be Shaped Like a Doughnut
NewbieV writes "The NY Times (reg., etc.) is reporting that data from the Wilkinson
Microwave Anisotropy Probe may suggest that the universe might be shaped like a doughnut or a cylinder: it might be possible, like in the old video game Spacewar, to drift off one 'side' of the Universe and reappear on the other."
Did anyone here actually *read* A Brief History of Time? Hawking described how the gravity of the universe may be so intense that it causes the universe to wrap around into a spherical shape. Of course this was just a theory back when he wrote the book.
Actually....in the episode where the Mensa society runs Springfield, Stephen Hawking shows up, and at the end says: "Homer, your idea of a doughnut-shaped universe is intriguing. I must steal it for my next book."
I'm out of my mind right now, but feel free to leave a message.....
Actually, no, they didn't. n-dimensional universes -- if they are compact -- are shaped like n-tori, not n-spheres. The question is quether they have genus one (and are thus flat) or have genus 2+ (are have negative curvature.)
We're talking about a Torus, not a spherical universe. If true, the universe is still 'flat', there's no 'wrapping' as you put it, it just repeats in all directions.
I am a science fantasy fan
Well, firstly, it has long been thought that the universe was closed. This is just suggesting that the universe might be topologically equivalent to the equivalent of the hypersurface of a hypertoroid, rather than the hypersurface of a hypersphere, as previously assumed.
Secondly, the opposite of a red-shift is a blue-shift. The complementary nature of red and green is a property of human eyes, not of the light itself. Red light is lower in energy; blue light is higher. Things rushing away from us as space expands would leave light from distant objects moving more slowly relative to us if not for special relativistic effects. With the effects, the energy of the light is reduced. However, you're right... when an object is approaching you, light from it is blue-shifted, and that would be what we should expect when the universe starts collapsing.
The question is assumed to not make sense. The surface of a torus has topological properties similar to that of the universe (according to the article). It's just a statement about what happens when you move a long way in one direction and how points in the universe can be reached from one another, not an assertion that the universe is sitting in some hyperdimensional 'space' outside the universe.
A different dimension. Maybe another alternate universe. Our donut may be one of many other donuts. As far as 4th-dimensional creatures like us our concerned, if you could look from 'outside' our universe, everything could look like a big blob within a dark void
As the donut (or sphere or what-have-you) represents space itself, the concept of something "outside" it doesn't really work. Only relationships between different parts of the universe are defined. Treating the universe as the surface of some object is just a trick to make it easier to visualize (otherwise it would just be a set of functions defining relationships between points).
Some of the inflationary models put the universe we can interact with within a larger space, but that just gives us disjoint parts of one larger universe. Much like the event horizon of a black hole, the interface between them would represent a boundary across which interaction and information flow is restricted, and different space/time coordinate systems would be used inside and outside them. (The inflationary bubble looks like an infinite space from the inside and an expanding bubble from the outside; all points on the boundary look like they're at the beginning of time from the inside.)
So, no Voyager-esque bright expanding shell or external vantage point in the simplest scenario, and something a bit different from what you're probably envisioning in the various inflationary models that posit bubbles within larger spaces.