Anthony Aguirre - What Would an Infinite Universe Mean?

Do stars and spaces go on forever? Do the numbers of galaxies, and even of universes, have no end? Is our universe infinite in size and contents?

[sundae]

The important part is where he says "it is another way of travelling faster than the speed of light". He defines an infinite universe as a universe that is expanding faster than the speed of light meaning that no matter how long you travel into one direction you will always be inside the same universe. This also why he says that from inside it looks infinite and from outside it looks finite.

[storksforever]

I guarantee that that everyone who is talking shit about this wouldn't have even the slightest idea of how to use any spacetime equations.

[Aguijon]

If i get it right, an infinite and a finite universe would look exactly the same because in both cases you reach a point from which you can't go any further.

[Lillianachimp]

I like how he says spacetime is 1 thing but then explains how it can be divided different ways...

[firstcause]

if the universe is finite then whats after that?

[l.clevelandmajor]

That was just a bunch of double talk designed to confuse the issue, in my opinion!

Here is my explanation of why the Universe must be infinite:
First let's define the word Universe. Look at the word closely, and you see that its prefix is Uni, which means one, or in this case, "All in one". Verse is a way of describing existence, as in this case, "That which exists." Put the two parts of the word together, and the meaning becomes "All that exists in one!" So by that definition (which by the way is the original definition of the word in science), there is nothing that exists anywhere or any time that is not part of the Universe. The supposed existence of other Universes, or if you prefer, a so called Multiverse is invalid according to that definition, because those supposed other Universes belong to the one Universe. Both Space and Time are also to be considered as part of the Universe, Space is the volume of the Universe itself, and Time is its duration. Add to that Matter and Energy, neither of which can exist all throughout Space or Time, because neither Space nor Time have an end or edge. Even if there is a finite amount of matter and energy, Space and Time are still endless.

This brings us neatly and as simply to the conclusion that the Universe must be infinite. let us do a thought experiment, in which you can live an infinite amount of time and travel an infinite distance. Your trip would never end! You'd keep going forever, never finding an edge.

Someone said once that Space might be curved back on itself, but this is not shown to be true by any collected data.If it were then there would still be that which is outside the curvature described, and again that must be included as part of the Universe. The description that says there is an edge is also invalid because to say there is an edge to anything is to indicate that there is something beyond that edge. Thus that too must be included as part of the Universe. No matter how you describe your edge to the Universe, the fact remains that there is no real edge at all. If there is no more matter or energy in the endless depths of Space than what we perceive to exist in our area of it, Space still continues on, and so too does Time. Therefore the Universe must be infinite!

[jscottupton]

What kind of a vehicle are they traveling in? Have they been traveling forever?

[lylecosmopolite]

If the universe were infinite, the night sky would be would be roughly as hot as the surface of a star. In fact, the night sky is mostly black, which means that one or more of the following must be true:
* the universe has a finite number of galaxies;
* not enough time has elapsed for the photons emitted by distant galaxies to reach us;
* universe is not isotropic.
But if the Big Bang is true, the universe began as a singularity a finite time ago. How can an infinite universe emerge in a finite time period?
Also consult:
Edward Robert Harrison (1987) Darkness at Night: A Riddle of the Universe, Harvard University Press.

[jamesruscheinski]

Is the space and time at start of universe being pushed to the farthest reaches of the universe by dark energy as measured by cosmological constant, such that the earth, sun and Milky Way are internal to the start of universe rather than external? If that would be the case, the future could now be where the universe began in quantum state, as the big bang start of universe was once the future?

[Lillianachimp]

The only thing that moves faster than light is space itself

[chevere]

is it not a contradiction in terms to speak of the volume of space?

[csdr]

I sense that Anthony is talking pure nonsense.