Cosmogenesis .

[Cyclone]

If the universe IS space and time, then talking about it not existing and thus "nothing" is by definition the absence of spacetime. Not just a vacuum which is just an area of space time with nothing in it.

I don't think we do really know that it's possible, nor can we really envisage it, when you picture the big bang in your head, for me at least, it's from the point of an outsider observer seeing an explosion, but there is no outside to be observing from. But if there was an origin, then because we can't get outside of time, we then immediately ask what came before it. Even though the very concept of before doesn't make any sense unless time exists, which it didn't until the origin event...

[sutty27]

I'm not so certain about your first assumption.. as for your second that's why I said the maximum diameter I would have expected was 28 billion light years.

 

What if we had multiple expansions of space and not just one big expansion of space.

 

Point A expands to create a bubble 372564 miles in diameter in one second.

Point B expands to create a bubble 372564 miles in diameter in one second.

Point C expands to create a bubble 372564 miles in diameter in one second.

Point D expands to create a bubble 372564 miles in diameter in one second.

Point E expands to create a bubble 372564 miles in diameter in one second.

 

The result would be something that is much larger than just one expansion.

[Cyclone]

Nothing can travel faster than light OK? That's kind of accepted as given. So you'd expect that nothing can expand faster than light speed.

 

Take a balloon mark a load of galaxies on it like a raisen pudding and blow the balloon up - that's the expanding universe.

 

Now, if you blow it up so fast that the edge is expanding at light speed, when measured to the other edge, then within the universe, everything is expanding at much less than light speed in relation to each other.

 

So you can blow it up faster and the edges are receding at faster than light speed, but still within the universe, everything is expanding at much less than light speed.

 

Best explanation I can give without some fearsome maths that I really don't want to have to try to understand again...

 

There's also the wrinkle in the bubble, that if the edge were receding (from us say) due to expansion, faster than the speed of light, then it simply disappears, we can't see that edge. The limit to what we can see is the point which is receding at the speed of light, because anything beyond that horizon cannot ever be visible to us, as the light cannot ever reach us. (Because the light itself is receding along with the space time expansion, so even though it's doing the speed of light towards us, it's actually getting further away).

 

---------- Post added 04-05-2016 at 11:12 ----------

 

What if we had multiple expansions of space and not just one big expansion of space.

 

Point A expands to create a bubble 372564 miles in diameter in one second.

Point B expands to create a bubble 372564 miles in diameter in one second.

Point C expands to create a bubble 372564 miles in diameter in one second.

Point D expands to create a bubble 372564 miles in diameter in one second.

Point E expands to create a bubble 372564 miles in diameter in one second.

 

The result would be something that is much larger than just one expansion.

 

If the expansion stopped then quite quickly we could see across this new space.

 

If the expansions continued then we would never know anything outside the expanding bubble we are within, because no light from one of the other areas could ever reach us.

[sutty27]

If the universe IS space and time, then talking about it not existing and thus "nothing" is by definition the absence of spacetime. Not just a vacuum which is just an area of space time with nothing in it.

I don't think we do really know that it's possible, nor can we really envisage it, when you picture the big bang in your head, for me at least, it's from the point of an outsider observer seeing an explosion, but there is no outside to be observing from. But if there was an origin, then because we can't get outside of time, we then immediately ask what came before it. Even though the very concept of before doesn't make any sense unless time exists, which it didn't until the origin event...

 

That to me is less likely than God did it.

 

Nothing exists not even the vacuum and one day for no apparent reason the universe popped out of that which didn't exist.

[truman]

There's also the wrinkle in the bubble, that if the edge were receding (from us say) due to expansion, faster than the speed of light, then it simply disappears, we can't see that edge. The limit to what we can see is the point which is receding at the speed of light, because anything beyond that horizon cannot ever be visible to us, as the light cannot ever reach us. (Because the light itself is receding along with the space time expansion, so even though it's doing the speed of light towards us, it's actually getting further away).

 

 

We're not going to get into Penrose diagrams are we?

[sutty27]

There's also the wrinkle in the bubble, that if the edge were receding (from us say) due to expansion, faster than the speed of light, then it simply disappears, we can't see that edge. The limit to what we can see is the point which is receding at the speed of light, because anything beyond that horizon cannot ever be visible to us, as the light cannot ever reach us. (Because the light itself is receding along with the space time expansion, so even though it's doing the speed of light towards us, it's actually getting further away).

 

---------- Post added 04-05-2016 at 11:12 ----------

 

 

If the expansion stopped then quite quickly we could see across this new space.

 

If the expansions continued then we would never know anything outside the expanding bubble we are within, because no light from one of the other areas could ever reach us.

 

Only if we was at the centre of our expanding bubble.

Our part of space in the expanding bubble could be moving towards another point in space from within another expanding bubble. That would mean some point in space are moving away and some are moving towards.

[truman]

Only if we was at the centre of our expanding bubble.

Our part of space in the expanding bubble could be moving towards another point in space from within another expanding bubble. That would mean some point in space are moving away and some are moving towards.

 

Has that ever been observed? Two points moving towards each other?

[unbeliever]

Only if we was at the centre of our expanding bubble.

Our part of space in the expanding bubble could be moving towards another point in space from within another expanding bubble. That would mean some point in space are moving away and some are moving towards.

 

I'm afraid it doesn't work like that.

We're on the surface of the bubble in this analogy, not at an arbitrary point within it.

[Cyclone]

That to me is less likely than God did it.

 

Nothing exists not even the vacuum and one day for no apparent reason the universe popped out of that which didn't exist.

 

I'd rather accept that we don't really understand it than have to invent a magic sky pixie what done it.

And of course if you invent a magic sky pixie, you now have to explain where that came from and what there was 'before' sky pixie existed.

[unbeliever]

I'd rather accept that we don't really understand it than have to invent a magic sky pixie what done it.

And of course if you invent a magic sky pixie, you now have to explain where that came from and what there was 'before' sky pixie existed.

 

Spot on. Gods can't answer these questions. They can only move them.