Cosmogenesis .

[truman]

But if each ship is a galaxy and they are all moving away from each other why do they regularly crash into each other.

 

You have to think on a larger scale...the people are the galaxies....the ships are the "local" areas of the universe..

Edited May 4, 2016 by truman

[sutty27]

You have to think on a larger scale...the people are the galaxies....

 

That would mean space is expanding between clusters of galaxies but not between the galaxies themselves, and that wouldn't explain why 2 huge clusters of galaxies can merge with each other.

 

I think it will turn out that the universe isn't actually expanding but is instead just creating new matter all the time.

[unbeliever]

That would mean space is expanding between clusters of galaxies but not between the galaxies themselves, and that wouldn't explain why 2 huge clusters of galaxies can merge with each other.

 

Space is very big.

https://en.wikipedia.org/wiki/Supercluster

 

The vast majority of other galactic clusters are moving away from our cluster.

That's down to the expansion effect. But they also have momentum. In a small minority of cases, their momentum is pushing them in our direction faster than the expansion of the universe is trying to push them away.

 

Of many billions of galaxies in the observable universe, Andromeda is one of about 100 which are headed toward us.

 

---------- Post added 04-05-2016 at 13:14 ----------

 

 

I think it will turn out that the universe isn't actually expanding but is instead just creating new matter all the time.

 

There's no indication of this.

[Cyclone]

That would mean space is expanding between clusters of galaxies but not between the galaxies themselves, and that wouldn't explain why 2 huge clusters of galaxies can merge with each other.

That's just a limitation of the analogy.

I think it will turn out that the universe isn't actually expanding but is instead just creating new matter all the time.

 

Well that really would require magic, as we understand it.

 

---------- Post added 04-05-2016 at 13:19 ----------

 

But if each ship is a galaxy and they are all moving away from each other why do they regularly crash into each other.

 

Depends on how you define regularly doesn't it?

 

According to the best estimates of astronomers there are at least one hundred billion galaxies in the observable universe.

That's a lot of opportunity for crashing.

 

And as someone has already pointed out, matter in the universe is clumpy. We have solar systems, galaxies, local group, cluster, super cluster. Each one is a clump on a different scale.

[sutty27]

 

Well that really would require magic, as we understand it.

 

It is claimed that matter can spontaneously pop into existence from a vacuum, so no magic would be required.

[DnAuK]

Space is very big.

https://en.wikipedia.org/wiki/Supercluster

 

The vast majority of other galactic clusters are moving away from our cluster.

That's down to the expansion effect. But they also have momentum. In a small minority of cases, their momentum is pushing them in our direction faster than the expansion of the universe is trying to push them away.

 

Of many billions of galaxies in the observable universe, Andromeda is one of about 100 which are headed toward us.

 

---------- Post added 04-05-2016 at 13:14 ----------

 

 

There's no indication of this.

 

I'm sure Sutty gets this - as do I. But if everything has momentum, as blew apart from a central point - how is any of that momentum bringing things crashing together? Using the balloon analogy from earlier, as you blow up the balloon do any of those dots get closer together and merge? No.

 

Now I'm sure gravity has a part to play in all this (probably THE part). But you can't argue that one explanation for the general observation being that most things are moving away but some things moving closer together could be multiple expansion points. Why must scientists invent ideas such as 'dark matter' and 'dark energy' - things we have yet to have proven, when another theory could exist?

 

All I'm saying is, from a layman's point of view, it sounds like a half decent explanation to me.

[unbeliever]

It is claimed that matter can spontaneously pop into existence from a vacuum, so no magic would be required.

 

Only if their properties completely cancel and only (from our perspective) for incredibly brief times.

[sutty27]

That's a lot of opportunity for crashing.

 

And as someone has already pointed out, matter in the universe is clumpy. We have solar systems, galaxies, local group, cluster, super cluster. Each one is a clump on a different scale.

 

How does expansion theory explain the clusters? why isn't it more uniform if there was only one expansion.

[Cyclone]

It is claimed that matter can spontaneously pop into existence from a vacuum, so no magic would be required.

 

Only if the anti matter also simultaneously pops into existence, thus meaning that it all balances out (and in most cases resulting in popping back out of existence immediately).

 

---------- Post added 04-05-2016 at 13:44 ----------

 

I'm sure Sutty gets this - as do I. But if everything has momentum, as blew apart from a central point - how is any of that momentum bringing things crashing together? Using the balloon analogy from earlier, as you blow up the balloon do any of those dots get closer together and merge? No.

 

Now I'm sure gravity has a part to play in all this (probably THE part). But you can't argue that one explanation for the general observation being that most things are moving away but some things moving closer together could be multiple expansion points. Why must scientists invent ideas such as 'dark matter' and 'dark energy' - things we have yet to have proven, when another theory could exist?

 

All I'm saying is, from a layman's point of view, it sounds like a half decent explanation to me.

 

The big bang was not an event that imparted momentum to the things within the universe that came into being.

Don't confuse the expansion of space (the surface of the balloon) with the things that exist within the surface of the balloon and can independently move about within that surface (remember, 2d analogy of 3d process).

 

---------- Post added 04-05-2016 at 13:45 ----------

 

How does expansion theory explain the clusters? why isn't it more uniform if there was only one expansion.

 

Gravity explains why matter clumps.

 

But this is worth reading.

 

https://en.wikipedia.org/wiki/Cosmological_principle

 

You've just about reached the limits of my A-level in physics and passing interest in cosmology and the origin of the universe btw. I never went far enough with the maths to get into how some of these theories came about or are supported mathematically.

Edited May 4, 2016 by Cyclone

[unbeliever]

How does expansion theory explain the clusters? why isn't it more uniform if there was only one expansion.

 

That is one of the key questions of modern cosmology.

The cosmic microwave background, which I expect you've heard of, is essentially the bright light from the early universe which has since been stretched out and in doing so has turned from light into microwaves. It shows that the early universe had some imperfections in it, probably due to quantum effects which would have been significant at this early time. As the universe expanded matter tended to coalesce around these imperfections which ultimately developed into the large-scale structure of the modern universe.

Essentially the surface of the balloon is not perfect and as it is inflated the imperfections grew.