- #31
heldervelez
- 253
- 0
This simple universe obviously do not colapse.
In the formulation we have to say how old is that matter.
Suppose the universe is infinite, homogeneous, static at the beginning (i.e. cold start) and started his existence just now, or at a finite time.
It cannot clump, it will not colapse, whatever the equations that someone can put forward.
The question of metric is irrelevant. We have objects equally spaced, and beeing all objects equal, a rod is constructed from one of them. 3D euclidian space is enough, because GR will have an overall null effect.
Ok. Now we displace one object from the 'correct' position. What happens now?
The answer is unexpected.
We will have a 'void', and the void will be growing, growing, slowly but exponentially growing, as we see in our marvelous universe.
To visualize : punch a hole in a balloon, and the hole will get bigger and bigger.
This universe is so simple that I've never found it discussed in the textbooks, but it adheres to reallity.
We are so used to hear that matter clumps, that we have difficulties to understand that void (empty space, no objects) repels matter, instead the more usual way 'matter atracts matter.'
As an aside effect the 2nd thermodynamic law breaks under this scenario.
The scenario is the same even if the universe is finite in extension provided that it is finite in time, because the gravitational effects propagate at a finite speed 'c'.
In the formulation we have to say how old is that matter.
Suppose the universe is infinite, homogeneous, static at the beginning (i.e. cold start) and started his existence just now, or at a finite time.
It cannot clump, it will not colapse, whatever the equations that someone can put forward.
The question of metric is irrelevant. We have objects equally spaced, and beeing all objects equal, a rod is constructed from one of them. 3D euclidian space is enough, because GR will have an overall null effect.
Ok. Now we displace one object from the 'correct' position. What happens now?
The answer is unexpected.
We will have a 'void', and the void will be growing, growing, slowly but exponentially growing, as we see in our marvelous universe.
To visualize : punch a hole in a balloon, and the hole will get bigger and bigger.
This universe is so simple that I've never found it discussed in the textbooks, but it adheres to reallity.
We are so used to hear that matter clumps, that we have difficulties to understand that void (empty space, no objects) repels matter, instead the more usual way 'matter atracts matter.'
As an aside effect the 2nd thermodynamic law breaks under this scenario.
The scenario is the same even if the universe is finite in extension provided that it is finite in time, because the gravitational effects propagate at a finite speed 'c'.