Is the universe finite?

Question

The Big Bang was at a single point at one time therefore no matter how fast or how long it has been expanding it should remain a finite amount. Yet, I keep hearing the universe is infinite on Yahoo Answers.

I know we can only see so far so the universe could be VERY VERY big, but if he Big Bang theory is correct than the universe cannot be infinite correct?

Answer 1

it is infinite

Just like the number of sands on  a beach is infinite.

Answer 2

One more time, the Universe in NOT infinite.  There is evidence that it is expanding.  Something which is infinite already can not get bigger.

The people who say it is infinite are ignorant of science.  Study astronomy at a university, not on an internet forum.

Answer 3

No one knows.

I saw a lecture once about this. They have mapped the edge of the known universe, it looks bumpy. There may be other universes with their own big bangs out there.

Answer 4

it is infinitely big

Answer 5

The Big Bang theory does NOT say that the universe was a single point.  What is says is that there was a singularity, which many people interpret as meaning "one point".  The word singularity is a mathematical expression that expresses an unbound state.

A point is an object whose "smallness" is unbound.  The perceived mass of an object traveling at the speed of light would be a singularity (it would be infinite, if such a mass could exist)... if the speed of light could be attained by a massive object.

In the equation f(x) = 1/(x-3),  there is a singularity at x=3.

In f(x, y) = 1/(x + y -2) the singularity has the shape of a line (not a point)

and so on.

The early universe was an object where the energy density (what we would call temperature) was unbound.  That is the singularity.

In any event, the earliest time we can go back is called the Planck Time, very close to time=zero, but NOT exactly zero.

Given our present understanding of physics, we cannot go back beyond Planck Time.  A lot has been written about that missing fraction of a second, but we have no way of checking.

If the universe is infinite now, then it was already infinite at that time.  The "visible universe" -- the portion we can see up to 14 billion light-years distance -- might have been extremely small (and definitely finite) at the time, but that is not necessarily the entire universe.

The probe WMAP was sent to analyze the Cosmological Microwave Background (CMB) radiation.  If the universe were actually smaller than what we can see (possible if the universe is wrapped onto itself, like the surface of a sphere is a 2-D surface, wrapped around a third dimension), there should have been some telltale signs.

WMAP looked specifically for these signs and did not find them.  So, the only thing we know for sure is that the universe is at least as big as what we see (diameter of 28 billion light-years in "proper distance", which is equivalent to somewhere around 156 billion light-years in "comoving distance")

The universe could still be infinite.  We have found no evidence aginst that possibility.

A flat, infinite universe does solve a lot of problems.  No need for an "outside"; no end, no border.  Also, no need to explain what the universe expands into: it expands into itself.

But that convenience itself is not a proof that it is infinite.

Answer 6

Maybe - it can also still be infinite and we are just not able to see past the horizon. That possibility also still exists.

Answer 7

Let me answer your question with a question. Let's say for example that you somehow find a way to the end of the universe. What would you see at the end? Would it be a wall? What's on the other side of the wall? A wall is something, even its made of nothing, no? How far does that wall go on? Tricky, huh?

Answer 8

Maybe-- but maybe NOT-- it has been measured at a "minimum" size of 156 billion light years wide--

http://www.space.com/scienceastronomy/my...

Answer 9

the universe is not infinite :) i see the universe to be like a giant sphere, if you try to go towards one point in the universe you'll end up eventualy in your starting position and that gives the impression that the universe is infinite.