If the Universe is infinite is matter therefore finite ?

Question

I first read the proposition in a scientific book about 15 years ago and was intrigued that there could be a value for the mass of matter in the Universe (albeit largely theoretical, unsubstantiable etc.). However I was convinced by Pumba the office techie that the proposition was false. For Pumba to be right, an infinite mass would have to be contained within an infinite space. Is this possible ?

Answer 1

I don't think it matters about the matter!

There is no answer so don't bother busting your brain cells to find one!

Answer 2

"An infinite mass would have to be contained within an infinite space." This assumes that an infinite mass has an infinite volume. I don't know much about this stuff, but aren't black holes a possible exception to that? And how does an infinite mass make sense with the Big Bang theory (which nobody has proven, remember)? I'm interested to know how the author of the book you read deduced finite matter from infinite universe. I could understand how a finite universe should mean a finite matter, but how does infinite universe mean finite matter? This is why I stick with easy stuff like computer programming.

Answer 3

Prima facie, if the Universe has infinite volume it would appear that it must have infinite mass. However, we know that a substantial part of the Universe consists of a vacuum, which has no mass. Therefore, must mass be finite? Well, not necessarily. In theory, half of infinity would still be infinity, wouldn't it?

Fortunately for those of us mortals who struggle to understand the concept of the sheer scale of the known universe, let alone an infinite one, a significant number of respected theorists suggest that perhaps the Universe is not infinite at all, which makes the question of comparative mass immaterial.

A finite Universe - there, my brain feels better already...except, if the Universe is not infinite, what do we call everthying that exists outside it?

Answer 4

Have you mistyped this?

Surely if you have INfinite matter then you need INfinite space as each time you add a little more matter then you need a little more space to put it?

Or if universe is INfinite then using any section of current known space it means that there MUST be matter in that space.

However if you take the big bang theory then all the matter that has ever existed is expanding from a single central point then matter must be finite even if it keeps expanding in to nothing.

Answer 5

It's been theoretically demonstrated that the universe cannot contain infinite stars. I forgot who, but someone figured out that if there were infinite stars, then wherever you looked in the sky your line of sight would eventually encounter a star, no matter how far away. Therefore, the entire sky would look as bright as the surface of the sun. Furthermore, if there was any intervening matter, such as dust clouds, these would eventually heat up themselves under the exposure of all that starlight, producing an equal amount of "blackbody radiation".

Answer 6

As far as I know, the universe is finite but expanding. Matter, which is one manifestation of energy, is also finite since the total energy value of the universe is constant. If matter was not finite then the density of the expanding universe would not decrease, which is not the case and, consequently, energy has to be created out of nothing. However there are always new theories and discoveries on the subject, and I must confess I'm not up to date.

Answer 7

I'm pretty sure the prevailing theory is that the universe is not infinite... they're just not sure of the shape, whether it's a sphere, or a hyperbolic paraboloid (which looks like a saddle), or somewhat flat.

Answer 8

It is clever in that the universe is finite, constantly increasing. i've got regularly questioned what lies exterior the universe, yet it is merely approximately impossible. i don't individually have self assurance in god, yet i've got self assurance he's countless in people's mind's eye. i'm not intending to offend all of us, merely answering the question. :)

Answer 9

The universe is not infinite, and neither is anything within it.

Answer 10

There is not reason to believe that it is finite. But the again there is no proof that there is reason to believe that it is infinite.

It is a conundrum.

There is no answer - only spectulation.