Brace yourselves for gravitational waves

[Excited Penguin]

Here is an article from the experts.

http://phys.org/news/2015-03-universe-fi...inite.html

My laypersons guess would not be either or, but both. I think off is finite, and on is finite, but going from one to the other could be infinite at the QM level. But sure, at this point we don't know.

That article doesn't talk about what you talk about. It talks about the implications of an infinite universe.

But my question is, don't we already know the universe to be finite because of the Big Bang? How could it possibly be infinite if it had a start?

[Brian37]

This is the first time I'm hearing this. So in 5 billion years the universe won't be able to sustain life anymore?

Yea where did he get 5 billion? I can see that lifespan for a planet or star, but considering the universe is 14 billion years old seems 5 billion would be lowball estimate for the end of the universe.

Not that simple, the separation between galaxies wont mean heat death, it will just simply mean whatever life that might exist unless advanced would end up perceiving there island as being all there is because the distance would be great. Heat death is when there is no more energy in the universe to use.  According to this article, expansion will lead to even the ripping apart of galaxies. But expansion to the point of not being able to see other galaxies will happen first.

But admittedly that is my take on it, here is the scientific article. 

https://en.wikipedia.org/wiki/Heat_death...e_universe

[Brian37]

Here is an article from the experts.

http://phys.org/news/2015-03-universe-fi...inite.html

My laypersons guess would not be either or, but both. I think off is finite, and on is finite, but going from one to the other could be infinite at the QM level. But sure, at this point we don't know.

That article doesn't talk about what you talk about. It talks about the implications of an infinite universe.

But my question is, don't we already know the universe to be finite because of the Big Bang? How could it possibly be infinite if it had a start?

I think you missed my point. Again, why cant it be both infinite and finite? You can literally draw a finite line on a piece of paper and have an infinite number of decimal places within that finite line.

AGAIN, although we don't know right now either way, my guess  OFF is not infinite and On is not infinite, but going from off to on back to off to on.......could be infinite. 

This isn't a problem once you consider Lawrence Krauss saying nothing is something. QM is freaky in that it doesn't say either way, but my point is why not an overlapping both? Off being temporary and on being temporary but going from off to on being infinite. That is what I mean by quantum twitch. The seeming nothing suddenly building to something leading to the observable on, which burns out and breaks down to "nothing" again.

[Alex K]

Where does it say that galaxies themselves will be ripped apart?

[Excited Penguin]

I'm not a big fan of wikipedia. Maybe if you found an actually published article about it.

Anyway, I remember reading an article of Krauss' and maybe reading about it in his A Universe From Nothing book as well, that our galaxy would eventually be driven so far apart from other galaxies that future humans wouldn't be able to tell there's a whole universe out there, beyond their galaxy(which we thought as well at a certain point in the past, before Hubble proved there's other galaxies out there). However, Krauss was referring to a far later date in the future than 5 billion years, if I'm not mistaken.

[Excited Penguin]

That article doesn't talk about what you talk about. It talks about the implications of an infinite universe.

But my question is, don't we already know the universe to be finite because of the Big Bang? How could it possibly be infinite if it had a start?

I think you missed my point. Again, why cant it be both infinite and finite? You can literally draw a finite line on a piece of paper and have an infinite number of decimal places within that finite line.

AGAIN, although we don't know right now either way, my guess  OFF is not infinite and On is not infinite, but going from off to on back to of to on.......could be infinite.

That's not exactly infinity. That's still a finite thing you're talking about. It's only infinite mathematically(or theoretically), but not really. Real infinity would simply mean that you could go in one direction forever, without ever having to stop or going in circles.

You can't have both infinite and finite space. That's absurd. How do you even imagine such a thing?


What OFF and what ON. What the hell are you talking about.

[Alex K]

There is a well defined notion of the spatial extent of the universe, and it is either finite or not. It could however be finite in one direction and infinite in another... All we know right now is that if it is finite, it appears to be bigger than the visible universe (otherwise it would show signatures in the CMB). If there was cosmic inflation, it is likely at least many many orders of magnitude bigger than the observable patch.

[Excited Penguin]

There is a well defined notion of the spatial extent of the universe, and it is either finite or not. It could however be finite in one direction and infinite in another...

I don't understand. How can it be infinite if it has a starting point from which it expands?

[Alex K]

There is a well defined notion of the spatial extent of the universe, and it is either finite or not. It could however be finite in one direction and infinite in another...

I don't understand. How can it be infinite if it has a starting point from which it expands?

It doesn't have to have that, that's a common misconception. The big bang wasn't an outward explosion that necessarily started in one point. Since relativity breaks down, and inflation likely took place driven by quantum fluctuations, we cannot trace ut back to size zero anyways, and such a singularity likely never occurred.

[Brian37]

Where does it say that galaxies themselves will be ripped apart?

Read the wiki article, those are the experts. I would assume that after the distances between galaxies become so great, if the expansion continues it would end  up pulling those things apart too, but again, that article explains it better than I can.