Is the Universe infinite?

Question

I'm an astrophysics student, but I can't wrangle a straight answer out my lecturers, books or classmates.
The observable universe is certainly finite, but what about the rest?

Yazan- Finite things can expand. Consider the set of integers. It's infinite, but you could insert half-integers into the set. It's still infinite, but also bigger.
Butthead- You have chosen your name well.

Answer 1

You're probably having difficulty getting a straight answer from your colleagues because no-one knows the correct answer. Scientists are pretty much certain that the actual universe is much, much bigger than the observable universe but we just don't have any data to give us an accurate estimate of its full size.
Some of the latest data from WMAP which is monitoring the Cosmic Microwave Background Radiation indicates a "flat" geometry to the universe. This is our best evidence so far that the Universe is either stupendously massive or even infinite.
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Zahbudar, your figures are wrong. NOTHING can currently be detected further away than 13.7 billion light years in any direction. That is what the observable universe is - the spherical region surrounding our point of view in the universe. Since the universe is approximately 13.7 billion years old, any light from objects more distant than the OU CANNOT have reached us yet.

Furthermore, the size of the universe is a perfectly valid topic of discussion and enquiry. What you have said is equivalent to saying we shouldn't be concerned about the origin of the universe or other questions because they seem "unanswerable". I say that is a position of ignorance.

Answer 2

Lets look at this another way. Infinite means that no quantifiable value exists.

However the laws of physics state that matter can not be created or destroyed therefore the universe contains a finite amount of matter and as such has a finite size at any given time.

In the physical universe nothing is infinite. If fact even in theoretical science practitioners will only say that something approaches infinity and should never say something is infinite.

Answer 3

There is insufficient data. All current observations are perfectly consistent with either a finite (closed) or an infinite (open) universe within experimental errors. The fact that the density is so incredibly close to the boundary between the two possibilities is called the Flatness Problem, and is one of the reasons inflation was introduced.

Answer 4

Well, since your lecturers are obviously far more educated than I am, I will yield to their wisdom and simply ask you why you are so hung up on this particular point. Ian Ridpath, author of ASTRONOMY, DK Publishing, NY NY, has stated that modern day scientists and astronomers have been able to detect objects in space as far away as 40 Billion Light Years in all directions from Earth. Certain other astronomers are making new discoveries of galaxies 13.7 Billion light Years distant on recent Internet Astronomy site news articles.
So with distances like that involved:
1.) No one will ever travel that distance from Earth.
2.) Anyone setting off on a journey to some location near there will be dead of natural causes long, long before getting there.
3.) Any situation or status reports they might send back will take Millions of, or Billions of Years to reach the Home Planet.

And, in summation, what possible difference does it make to the man in the street, your average bus driver, or a cop on his beat? Please understand I do not mean to be offensive. I am just saying that the distances we know and understand are so immensely vast, why not absorb the knowledge that man has acquired, and skip over those things which have "no apparent answer. " Dwelling upon those unanswerables is an exercise in futility.

Answer 5

The universe is a finite entity with a maximum and minimum size.
The red shift is interpreted as the universe being in a state of accelerated expansion.
The universe expanded from the beginning at the speed of light.
It will continue to expand until it reaches it's maximum size and begin to go out of existence.
It is not possible to increase it's expansion speed.
There is another explanation for the apparent red shift.

Answer 6

I do know that theories claim that it is expanding, and will be so for a long time until there exists no attraction between any 2 bodies in the universe, causing the end of it.... anyways doesn't 'expansion' mean that make it is finite? it cant get any bigger if it were infinte