Do you believe the Universe is infinite?

[Damocles]

So at the point the Universe was expanding it contained no mass?

sorry to ask such a stupid question but I can never quite get my head around these things

Not exactly. Spacetime is an actual substance - it is the thing that is warped by gravity and sometimes called the "fabric" of the Universe. Here's an artists impression of the mass of the Earth warping spacetime:

You see this is all that gravity IS. When somebody is talking about the gravitational force of something, they are generally talking about how much that the mass of something warps spacetime and the effect of something close to it. This explains how orbits work and why people say that we aren't really "orbiting" around the Sun but instead are "falling" around the Sun:

Gravity is the name we give for organised falling. Things fall down the slope towards the big thing then shoot off up the other side until they are pulled back down and go past it then shoot off to the other side. It also might be now easier to show why nothing can escape a black hole but things can orbit a Sun. Think of the energy/speed needed to achieve that in each of these warping of spacetime:

[bigimg]http://i.stack.imgur.com/K7czr.png[/bigimg]

Remember though that this is just a very overly simplified version of the ideas here and in presenting them in such a way we lose accuracy. Spacetime isn't 2 dimensional obviously, here it is in a more 3 dimensional context:

This might explain to some why gravity exists on Earth and we don't float off into space if you remember that spacetime is everywhere and is warped to differing degrees by everything that has mass including me, you, the atoms in my cup of tea and the Sun.

Anyway, spacetime itself was the thing that expanded quicker than the speed of light and not the things that have mass and warp spacetime. The "grid" you see in the above pictures was the thing that expanded, the objects sat on top of the grid didn't and those are the things that are limited by the speed of light. You might actually be able to see why the speed of light is the speed limit now - for something to have that much energy it would have to have an infinite mass as the faster you go the 'heavier' something gets (like the difference between me throwing a bullet at your head and shooting it out of a gun). The infinite mass would provide a huge warping of spacetime that would require an infinite energy to travel through. The speed of light in a vacuum has nothing special about it, it is just a substance that travels at the fastest possible velocity in the Universe. The fastest possible velocity would exist whether light travelled at that speed or not. Light just happens to have no mass thus travels at the speed limit. Basically the speed limit isn't light, light travels at the speed limit.

 

[101toMR]

Maybe we haven't got the intellect to understand the true meaning of "forever" or "Infinite"?
It doesn't stop us trying to rationalise it but it's difficult to believe we re ever going to get to the point of proclaiming that's it.
Interesting points in this discussion none the less.

 

[TangerineSteve17]

I don't understand your point number 1 in reference to what I said mate.

Surely if it is infinite then eventually you will come across every eventuality?

I am quite amateur in this field but I am interested.

I might be leading you astray mate but I think your infinity doesn't mean the same as Damocles'. Einstein said the universe is infinite before these multiverse multi-world theories came up. So I assume in his relativity he meant because the universe is ever-expanding, then what is it expanding in to? It seems right to say whether there is a boundary or not, it is infinite.

I could be wrong about the last bit, but infinity doesn't mean everything happens infinitely.

Cheers pal.

So to simplify, when it's said the universe is infinite, it means it will forever expand?

I'm keen to see what Damocles has to say also.

What is this? the third degree? :)

No, i'm not sure mate, still learning, hopefully Damo or someone will straighten it out for us.

 

[Ban-jani]

I might be leading you astray mate but I think your infinity doesn't mean the same as Damocles'. Einstein said the universe is infinite before these multiverse multi-world theories came up. So I assume in his relativity he meant because the universe is ever-expanding, then what is it expanding in to? It seems right to say whether there is a boundary or not, it is infinite.

I could be wrong about the last bit, but infinity doesn't mean everything happens infinitely.

Cheers pal.

So to simplify, when it's said the universe is infinite, it means it will forever expand?

I'm keen to see what Damocles has to say also.

What is this? the third degree? :)

No, i'm not sure mate, still learning, hopefully Damo or someone will straighten it out for us.

No worries mate.

I've been kind of obsessing over politics myself, I intend to start reading more about this.

Think I'm going to start with Laurence Krauss.

 

[Damocles]

Cheers pal.

So to simplify, when it's said the universe is infinite, it means it will forever expand?

I'm keen to see what Damocles has to say also.

There's no real proof to suggest that the Universe is infinite, only that our current observational and mathematical models imply an infinite Universe pretty strongly and that's the most scientific answer.

In terms of expansion, the Universe is currently thought to expand forever. It's both infinite and expanding at an increasing rate.

 

[Damocles]

Maybe we haven't got the intellect to understand the true meaning of "forever" or "Infinite"?
It doesn't stop us trying to rationalise it but it's difficult to believe we re ever going to get to the point of proclaiming that's it.
Interesting points in this discussion none the less.

People try to think of infinity as a number rather than a concept.

How many even numbers exist? Infinite.

How many odd numbers exist? Infinite

How many odd OR even numbers exist? Infinite.

As you should already be able to tell though, some infinities are bigger than other infinities. Helpful video on the topic here:

[video]https://www.youtube.com/watch?v=lA6hE7NFIK0[/video]

 

[Ban-jani]

Cheers pal.

So to simplify, when it's said the universe is infinite, it means it will forever expand?

I'm keen to see what Damocles has to say also.

There's no real proof to suggest that the Universe is infinite, only that our current observational and mathematical models imply an infinite Universe pretty strongly and that's the most scientific answer.

In terms of expansion, the Universe is currently thought to expand forever. It's both infinite and expanding at an increasing rate.

Okay thanks for the post.

Guess it becomes frustrating having to explain so many times but us amateurs do appreciate it.

 

[Damocles]

Okay thanks for the post.

Guess it becomes frustrating having to explain so many times but us amateurs do appreciate it.

Not really mate, this stuff is ridiculous because it's unintuitive. The problem is that everybody tends to learn new concepts by visualising it and thinking "oh, it's a bit like this" which then informs them enough to learn about why it's actually not like that and a totally different thing. But the first bit is the difference between the ability to go on and learn and exasperated frustration.

Unfortunately the Universe and other things like spacetime and the Big Bang are like nothing that we humans ever really come across so finding the right visualisation is tricky, and often poor analogies lead to poor conclusions such as how when people use the expansion of a balloon to explain the expansion of the Universe. Explaining these types of things shows you the difference between bad analogies and good analogies which shape my own understanding. It actually helps me to contribute to these threads probably more than anybody else to be honest. Win-win.

 

[pudge]

So at the point the Universe was expanding it contained no mass?

sorry to ask such a stupid question but I can never quite get my head around these things

Not exactly. Spacetime is an actual substance - it is the thing that is warped by gravity and sometimes called the "fabric" of the Universe. Here's an artists impression of the mass of the Earth warping spacetime:

You see this is all that gravity IS. When somebody is talking about the gravitational force of something, they are generally talking about how much that the mass of something warps spacetime and the effect of something close to it. This explains how orbits work and why people say that we aren't really "orbiting" around the Sun but instead are "falling" around the Sun:

Gravity is the name we give for organised falling. Things fall down the slope towards the big thing then shoot off up the other side until they are pulled back down and go past it then shoot off to the other side. It also might be now easier to show why nothing can escape a black hole but things can orbit a Sun. Think of the energy/speed needed to achieve that in each of these warping of spacetime:

[bigimg]http://i.stack.imgur.com/K7czr.png[/bigimg]

Remember though that this is just a very overly simplified version of the ideas here and in presenting them in such a way we lose accuracy. Spacetime isn't 2 dimensional obviously, here it is in a more 3 dimensional context:

This might explain to some why gravity exists on Earth and we don't float off into space if you remember that spacetime is everywhere and is warped to differing degrees by everything that has mass including me, you, the atoms in my cup of tea and the Sun.

Anyway, spacetime itself was the thing that expanded quicker than the speed of light and not the things that have mass and warp spacetime. The "grid" you see in the above pictures was the thing that expanded, the objects sat on top of the grid didn't and those are the things that are limited by the speed of light. You might actually be able to see why the speed of light is the speed limit now - for something to have that much energy it would have to have an infinite mass as the faster you go the 'heavier' something gets (like the difference between me throwing a bullet at your head and shooting it out of a gun). The infinite mass would provide a huge warping of spacetime that would require an infinite energy to travel through. The speed of light in a vacuum has nothing special about it, it is just a substance that travels at the fastest possible velocity in the Universe. The fastest possible velocity would exist whether light travelled at that speed or not. Light just happens to have no mass thus travels at the speed limit. Basically the speed limit isn't light, light travels at the speed limit.

Like a cone of ignorance?

 

[hilts]

I don't know why I read these threads, I am none the wiser and my head hurts, bloody science geeks can never put across ideas to us dumb folk, if it can't be explained with a balloon and a few marbles then I'm putting it down to God