If the universe is infinite, how is it expanding?

[glader]

I hope in my lifetime，the universe don‘t explode，who cares

The universe has appeared to have had its day in the explosive phase and you can only look forward to a cooling of the universe, this of course won't be in the lifetime of even our solar system though. Technically it's a slowly occurring process but at least not a phenomenal step towards that era of our universe will occur within the lifetime of our sun.

[Mnevis]

Why?

If there were objects farther away than the explosion front of the Big Bang, they must have existed outside the epicentre of the Big Bang (which is a contradiction, assuming that this universe was created from a single point).

I don't know exactly. Like I said, I'm not a physicist or cosmologist. Maybe someone here can better answer the question, all I can say is that I'm pretty sure that the concept "explosion front of the Big Bang" or edge of the universe is not something that exists in the current cosmological models. I guess I can try to find some web page explaining it.

[Matchu]

He's pretty spot on on what he's saying, the universe can not have expanded faster than light travels through a vacuum therefore one can conject that an approximation such as the one he has posted can give you a decent idea on the volume of the universe.

There is a large amount of Universe that we've never seen thanks to the expansion of the universe.

Also, as a Youtube Blogger is fond of saying, there's no "edge" to the Universe.

[glader]

I don't know exactly. Like I said, I'm not a physicist or cosmologist. Maybe someone here can better answer the question, all I can say is that I'm pretty sure that the concept "explosion front of the Big Bang" or edge of the universe is not something that exists in the current cosmological models. I guess I can try to find some web page explaining it.

Any postulation against the theory that there is nothing beyond this front would imply that there was matter outside of the Big Bang present at its occurrence otherwise there should be what you could consider at least an edge to the universe created as we know from the Big Bang.

[Deleted]

I have no idea whether anything is infinite or not. Especially the Universe.

I think though that when you are talking about space, matter and energy for that sake you should be very careful to describe them as infinite, because infinite is a particular kind of quality that opens up for a whole lot of negations, neccesities and exclusions.

If something is infinite it is also unmeasurable, it has no number and is ever-fulfilling.

I don't think the Universe fits that bill, but other things may do. On further thought, forget the math BS that was here lol. I don't know if anything at all is infinite.

Seeing how finite matter such as the Earth, space such as the distance between the Sun and the Earth, and energy such as heat in your light bulb is then it would very much surprise me if the Universe should be special from those and be infinite. I wonder what happens or anything when you bump into the borders of the Universe or if anything else is outside.

[glader]

There is a large amount of Universe that we've never seen thanks to the expansion of the universe.

Also, as a Youtube Blogger is fond of saying, there's no "edge" to the Universe.

Without an agreement between a definition of 'The Universe' this topic isn't debatable. If you claim all matter derived from the Big Bang is the known Universe then there surely would be an edge, albeit in motion, but otherwise the idea wouldn't make much sense that our universe was once at a central point.

Also, I would hope that this Youtube blogger you're referencing isn't MinutePhysics because even his simplistic videos are flawed in such a way to push his point with false mathematics. Mostly his work on infinity, I can not bear to watch much more than that.

[Matchu]

Without an agreement between a definition of 'The Universe' this topic isn't debatable. If you claim all matter derived from the Big Bang is the known Universe then there surely would be an edge, albeit in motion, but otherwise the idea wouldn't make much sense that our universe was once at a central point.

When people talk about the "universe" they often mean the observable universe. That, I guess technically, you could say has an edge where the observable becomes the unobservable to an observer on Earth since it's pretty much a sphere. But if we're talking about everything, then there can't be an edge. Because that implies that it's expanding into something; the big bang isn't forcing the galaxies away from each other. The...fabric of the universe is just being stretched. It's like asking where the big bang occurred (current thinking says everywhere).

Also, I would hope that this Youtube blogger you're referencing isn't MinutePhysics because even his simplistic videos are flawed in such a way to push his point with false mathematics. Mostly his work on infinity, I can not bear to watch much more than that.

Can't say I've heard of them but I'll go watch them.

[Kivimetsan]

I don't see how anything could be infinite, something has to end sometime right?

[Matchu]

I don't see how anything could be infinite, something has to end sometime right?

Count up from one.

[bluejaye]

I'm obviously not even close to being an expert but I've always wondered why we assume the universe is infinite. If there are multiple galaxies within the universe, why wouldn't we assume that there might be multiple "universes" within an even bigger body.

Think about it like this: Originally the earth was the center of all things. Then we realized there was a solar system. Then we realized that our solar system was actually one of many in a galaxy. Then the galaxy is one of many in the Universe. But then the Universe is it? Based on that logic wouldn't it be more likely that the universe is just one of many in an even larger body that we just don't have the comprehension or technology to observe yet?

[glader]

When people talk about the "universe" they often mean the observable universe. That, I guess technically, you could say has an edge where the observable becomes the unobservable to an observer on Earth since it's pretty much a sphere. But if we're talking about everything, then there can't be an edge. Because that implies that it's expanding into something; the big bang isn't forcing the galaxies away from each other. The...fabric of the universe is just being stretched. It's like asking where the big bang occurred (current thinking says everywhere).


Can't say I've heard of them but I'll go watch them.

No I'd recommend AGAINST watching them, a very large waste of time. I still laugh when I picture his video about infinity where he sums two incomplete sets, of different element length, and then claims they converge at -1. Is it not apparent to everyone that he just summed 5 elements of 1 set and 6 of another? I facepalm every time, don't waste your time. It's misinformation at its finest.

Also we cannot claim with absolute certainly that there is nothing/something on the edge of the matter that is derived from the Big Bang. We may not know for many generations, we can certainly guess. Sometimes we can even guess based on other evidence but it's certainly a mystery that no one should claim they've solved yet.

[Matchu]

I'm obviously not even close to being an expert but I've always wondered why we assume the universe is infinite. If there are multiple galaxies within the universe, why wouldn't we assume that there might be multiple "universes" within an even bigger body.

Think about it like this: Originally the earth was the center of all things. Then we realized there was a solar system. Then we realized that our solar system was actually one of many in a galaxy. Then the galaxy is one of many in the Universe. But then the Universe is it? Based on that logic wouldn't it be more likely that the universe is just one of many in an even larger body that we just don't have the comprehension or technology to observe yet?

There's a lot of interest in whether there's another Universe (or many others) in Physics. It's just that, by their nature, they're unobservable.

[Polution93]

That depends on how you're using "infinite." In size? Well, you have to remember that, at one point in time, the universe was as small as you are. At one point in time, the universe was smaller than all the quarks and leptons we know of. So, one must ask, was the universe infinite in size then? If so, why? If not, then when does one thing become large enough to be considered "infinite?"

Sorry to bring up more questions, but I live for this stuff. Infinity has always been a favorite topic of mine. Cheers!

[Deleted]

That depends on how you're using "infinite." In size? Well, you have to remember that, at one point in time, the universe was as small as you are. At one point in time, the universe was smaller than all the quarks and leptons we know of. So, one must ask, was the universe infinite in size then? If so, why? If not, then when does one thing become large enough to be considered "infinite?"

Sorry to bring up more questions, but I live for this stuff. Infinity has always been a favorite topic of mine. Cheers!

You can't say something is large enough or too large to be infinite. Infinity is endless. Infinity has no possibilities, neccesities or restrictions. It makes me wonder if anything at all is infinite.

[semaphore]

The exact same question had been asked and answered multiple times in your previous threads.

The universe is not expanding, the space between everything within the universe is.

What's the point of making threads on the same topics over and over if you never actually want to learn anything from them?


---------- Post added 2012-10-11 at 02:56 AM ----------

He's pretty spot on on what he's saying, the universe can not have expanded faster than light travels through a vacuum

No, that is completely wrong. There is nothing stopping the universe from expanding faster than the speed of light.

[Angella]

Let me make it really simple:

Infinity + 1 = Infinity.

I hope that clears some stuff up for you.

[semaphore]

Without an agreement between a definition of 'The Universe' this topic isn't debatable.

The universe is generally defined as all that exists.

If you claim all matter derived from the Big Bang

Matter is not derived from the big bang. The big bang was a point in time when all matter in the universe was at one point.

Though I suppose given that we appear to be in a flat universe, the big bang could be around the point where our universe and by extension all matter in it came from nothing.

[Deleted]

If you believe in the Big Bang, consider the following:
Travel in a direction, mentally, at just over the speed of light. Eventually, you will reach the explosion front of the Big Bang. It is dissipating more and more, but still expanding.

If you believe in the Big Crunch, add the following:
The effect of gravity on the objects in the centre of the universe will eventually cause the objects at the Big Bang wave front to slow and eventually return to the rest of the objects in the Universe.

You're completely wrong though. The Big Bang wasn't an explosion, it was a rapid expansion of something into nothing. To put it simply.
The reason we see back in time when we look outwards in the universe is because of the time it takes light to travel to us, not because there is an edge of an explosion that keeps expanding.
But matter shouldn't be expanding in the way it does, everything speaks against it doing so. So there is something fundamental that we've yet to discover, that will expand on what we already know. Pun intended.

To all the science and physics fanatics out there i have a question for you.
If the universe is infinite, how is it expanding?

It's one of the big questions actually. To my knowledge, there is no definitive answer, but a few ideas.

Everything we know, says that matter should be drawn together, but with a metaphorical middle finger, galaxies are actually moving apart. No-one knows why, but one thesis is called Dark Matter. Dark Matter is there to fill in a hole, both literally and figuratively, and we don't know if it excists.

[Taurous]

The matter in the universe is expanding, not the boundary, we don't know if there is a boundary.B

[Deleted]

The exact same question had been asked and answered multiple times in your previous threads.

The universe is not expanding, the space between everything within the universe is.

What's the point of making threads on the same topics over and over if you never actually want to learn anything from them?


---------- Post added 2012-10-11 at 02:56 AM ----------


No, that is completely wrong. There is nothing stopping the universe from expanding faster than the speed of light.

Because new conclussions can be reached and new information be had.

Would his statement be related to that we know of no particle that can travel faster than the speed of light? Wouldn't that mean that the universe can't have expanded faster than the speed of light?