If the Universe is curved (call it a hypersphere), is there the possibility of looking all the way through the Universe at ourselves?
The ultimate in self-reflection.

I've seen something very similar to that in the Nevada desert. ;)

The universe, for our purposes is flat. If it is curved, it is so massive that for as far out as we can see, it's flat. And, considering we can see out pretty far, we can treat the universe as if it was flat.

To attempt to include conjecture where there is no evidence is akin to religion, not science.

In your dreams, grasshopper.:p

i think if that happened, i would never sleep again. but, it would be kind of cool to have 8 cars and all of those doodads. hey, that gm key wasn;t a corvette, was it?...i might reconsider this....

without conjecture, there is no theorum, without theorum, there is no theory. without theory, there is no discovery. without....

you smell what i'm cookin?

Hence the phrase "theory allows for", and "which would explain", rather than "proves" and "explains".

But space does curve! Einstein showed that gravity is actually caused by the mass of objects causing a curvature of space.

If there was enough mass in the universe to stop expansion, then that would mean that the curvature of the universe is closed in on itself, the same way a black hole's gravity closes it off from the rest of the universe.

It is not religion to consider this kind of thing, scientists have to speculate in order to come up with theory.

You left out the first part there, observation.

So if there is a complete lack of evidence (e.g. you do not observe something), then why spend time with the rest of your thought process? The basis of science is observation and repetition. Religion (or more accurately faith) skips the first step (observation), and moves directly to conjecture.

One can apply this process to another field very closely associated to science; invention. But these two fields, while relying heavily on one another, are not one in the same.

While, "necessity is the mother of invention", inventors rely heavily on faith, which is the lack of evidence.

So yes, LJ you're on the menu, but you are trying to skip right to dessert.

Slart,

Local space-time can be distorted, bent and shaped by the objects on it, which is why we have gravity. In fact, space-time can be so badly distorted as to bend back on itself, which is what we think are black holes.

This is all on a local level; the whole of space-time (e.g. the universe) is flat. Think of it this way, if the universe is expanding from a single point (essentially, we can argue those semantics/theories another time), and the universe comprises everything then what is causing the universe to bend back on itself?

I agree, speculation is not a bad thing, but to apply speculative theories (those that go against observation) is just bad science. We observe that the universe is flat, and it may not be flat, but since, what we observe is a flat universe, and our theories fit this observation, then why clutter the theory with bad science?

This may sound a lot like "here there be dragons" arguments of a flat earth from the 13th or 14th century, but remember, all you have to do to prove the earth is round is stand up. Watch the sun set over the horizon (not trees or a house, something like a beach is good), and as soon as it completely disappears, stand up. Check your math if you want to, but if the world was flat you would not be able to see the sun again. And, though I'm not 100 percent sure on this point, I think that section of geometry was around well before 1492.


*edit* I spell like a six year old

Oh shit. I'm going to have to read "A Brief History of Time" again.

I have the edition with the nice color pictures.

I'm fighting an urge to just curl up in a little ball of agoraphobia and wait for the peaceful sleep of oblivion. My. There's lots of stuff that's very very far away, isn't there? :worried:

And you guys are geeks. :D

Eratosthenes of Cyrene proved that the earth was round and even accurately computed it's circumference prior to his death in 194 B.C.

See below link for more details:
http://www.phys-astro.sonoma.edu/obs.../eratosthenes/

I realize that belief in the bible and God isn't too popular around this message board, but if you're of that bent this is what the bible has to say about the earth being round:

(NIV) Isaiah 40:22 He sits enthroned above the circle of the earth,
and its people are like grasshoppers.
He stretches out the heavens like a canopy,
and spreads them out like a tent to live in.

Did Columbus know that the earth was round? How bout this nasa site?
http://pwg.gsfc.nasa.gov/stargaze/Lcolumb.htm

So why did my teachers tell me the whole flat earth crap in school? Who knows?

Sorry, didn't mean to be a thread jumper

I think i took your last sentence of your previous post out of context.

this one:
I had always concieved of the universe as 3D. An expanding shpere. I would consider that to be "curved". What do you mean when you say that the universe is "flat?"

Einstein's equations take the amount of matter and energy in the universe (assumed, again by the consideration of symmetry, to be distributed uniformly) and as output, they give the curvature of space.

The tough part is... how much matter and space is there really out there?

The way I understand it, if all matter and energy in the universe were to be smeared uniformly throughout space, and if, after this was done, there turned out to be more than the so called critical density of of 10 to the -23 grams in every cubic meeter (about five hydrogen atoms per cubic meter) Einstein's equations would yield a positive curvature. If there were less than the critical density, there would be a negative curvature, if there were EXACTLY the critical density, the equations would tell us that space has no overall curvature.

It's impossible to prove this without knowing how much matter and energy is out there, and how it's spread out. Don't you agree?

They are only beginning to delve into "dark" matter and speculate their could be more of it than any matter we were formerly aware of.
But, the WMAP (WILKINSON MICROWAVE ANISOTROPY PROBE) team has come up with a time line. :eyebrow: