Slashdot Mirror
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."
...the Cop of the Universe?
The Krispy Kreme Endowment for Excellence in Cosmology.
2 dimensional universes are shaped like donuts. 3 dimensional ones like ours are shaped like hyperspheres.
I guess they forgot to carry the 1.
I have been pwned because my
Those of us who have played games like Space Wars, Asteroids and Star Castle were already well aware of the toroidal truth.
no registration required link in printer friendly format (otherwise it's five pages)
More images from probe homepage
....cosmic size donut with solar sprinkles.
/me drools
Then in theory, we'd be able to see the same part of space from two vantage points, assuming that they're not farther away from us than the distance that light could have travelled since the universe came into being, assuming that one believes in the big bang theory.
So, would this mean that if we can't see one point from two directions now, that if we suddenly can, we've reached the halfway point of the life of the universe? Would we lose the redshift in favour of a green shift?
IBM had PL/1, with syntax worse than JOSS,
And everywhere the language went, it was a total loss...
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.
Namaste
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.....
But then what the hell is the jelly?
"I only speak the truth"
Karma: null(Mostly affected by an unassigned variable)
Voyager could also become the first device of our civilization to sail around the entire universe?
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
The article says that an experiment is going on that could find this out, but it is only possible to measure up to 28 billion light years which is most likely too small, even if the universe is finite.
if (particle->position.x < LEFT_LIMIT)
particle->position.x += RIGHT_LIMIT - LEFT_LIMIT;
else if (particle->position.x >= RIGHT_LIMIT)
particle->position.x -= RIGHT_LIMIT - LEFT_LIMIT;
.... ... }
int main (void) {
I've admired Dr. Tegmark's home page since he was a grad student, not so much for the design skills (ha!) but as an exemplar of mixing serious and non-serious publications for other colleauges and onlookers to enjoy, explore, and learn from. Tegmark gets the web. As for the science, some of it I can actually understand.
I would also commend to the curious Slashdot reader a couple items I found facinating from the 'non-serious' section of his website:
a very cool diagram of "Relationships between various basic mathematical structures" from his Theory of Everything paper
and another paper addressing the question: Why does the universe have 3 spatial and 1 time dimension?
--LP
Space is a toroid with finite size? Augh, I must be trapped in a static warp bubble! CleverNickName, this is all your fault!
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.
-Begin Jargon-
A torus (dougnut) is topologically equivalent to a square with sides identified (like the Space War).
-End Jargon-
Discontinuous or stuff like that is not really important concept. Whether you are "magically" transported or not when you reached the end is just a matter of choosing the right coordinates.
Also, curved universes do not enter the argument. Curvature is a statement on Geometry of the Universe, while being a Dougnut is a Topological Statement.Both of completely independent of each other. A Toroidal Universe can be flat (like, hey , a square with sides identified!). A curved universe can be a plain sphere.
Mode (3) smart-aleck mode. Press * to return to main menu.
Imagine you're a 2-D dude wandering the earth (which is really a 3-D globe like you'd find in a classroom). You can walk and walk and never hit a wall but there's a finite amount of 2-D space. Now imagine you're a 3-D dude... This is where my feeble brain says 'help!'.
The analogy would seem to back up the article; whatever direction you take if you walk long enough you end up where you started.
It was discovered that the internet is shaped like a pringle.
On learning of this news Ford Motor Company immediately sent the universe a "cease and desist" letter, claiming violation of their trademark "Taurus."
While someone was trying to explain to a Ford executive that "Taurus" was a different word, and only applied to to an abstract portion of space, not the universe, and the word "Torus" refered to a donut shaped object, said executive got a blank look in his eye, muttered the words, "Hmmmmmmmmmmm, Donut," and wandered off.
KFG
They are sound waves in the looses sense of the word.In the sense that you have stuff (the photon-baryon fluid) and a wave is travelling through it (like sound waves travelling through air).
Gravity waves exist of course, but we have no way of detecting them yet since their signature is much much much harder to detect.
Mode (3) smart-aleck mode. Press * to return to main menu.
Remember the rubber-sheet/morning glory shaped deformation model of gravity? Some time back I recall a description of a black hole as dropping such a BIG marble on the rubber sheet that it keeps going down, stretching the "rubber sheet" forever, at least as fast as the speed of light. Think a "taffy sheet", or a "stem" of the "morning glory" stretching like a stream of honey.
It's easy to see why enough gravity keeps light ORBITING the gravity from spiraling out and away. But this also explains why light going STRAIGHT AWAY from the center of the hole never gets out - space is being stretched at least as fast as it moves (or maybe even faster), so it never makes it out of the hole.
Well, this got me thinking: "What does a black hole look like from the INSIDE? What would one see from the viewpoint of the matter that was already there when the event horizon formed?"
And the answer seemed to be: "An expanding universe, starting from a very small but finite volume and expanding indefinitely, containing a large-but-finite amount of matter, which was initially compressed into an EXTREMELY dense lump - perhaps a quark fluid or denser."
In other words, something like the current universe. Perhaps with the moment of the formation of the event horizon corresponding to the end of the big-bang model's "inflationary period", but eliminating the need for a faster-than-light inflationary period.
Cosmic background becomes the layer of matter and energy just below the event horizon, which is just getting here now. Cosmic background structure represents the matter distribution at that level at that time - a fossil of the orbital dynamics of the accretion cloud. (I don't think you get to see an "inside view" of the infalling half of the Hawking radiation.)
You can go in any direction at up to the speed of light and never reach "the edge", which is (from your viewpoint) receeding at lightspeed.
Not being a professional physicist, at this point I haven't attempted any mathematical models or resolutions with any of the current cosmological models. So I have no idea if I'm just spinning a yarn or if this can be pounded int shape for testing against the real universe. But it might be interesting to try some time.
(The concept of gravity indefinitely stretching the coordinate system also leads to another possibility: Can gravity be modeled as masses constantly "sucking up" the coordinate system, which stretches between them meanwhile?)
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
Even if the hypertori topology of the universe is correct it doesn't imply that the universe has any particular curvature, it's still possible that it has positive, negative or flat intrinsic curvature.
You have to remember that the curvature of a torus embeded in 'flat' 3 space is purely an artifact of that embeding and not intrinsic in the topology of the torus. More specifically, there exist mappings from the embeded (intrinsicly curved) surface of the three dimensionally embeded torus to topologically identicle spaces that have everywhere flat intrinsic curvature.
As a thought experiment, consider a cube where the faces are portals to their oposites. Internally, this construct has the topology of a hypertorus but an everywhere flat topology.
For some nice diagrams and comentary that explain curvature (of the important, intrinisic kind) rather well, take a look at this, just skip over any of the math thats beyond your abilities, it's not really needed to understand the concepts.
Realities just a bunch of bits.
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.
If you know anything about topology, you'd know that coffee cups are doughnuts.