What is the compression ratio to get the universe back to singularity?

Question

It is a scientifically proven fact that the universe began with all matter compressed into a mass smaller than the point af a needle. I'm wondering how much pressure or gravitatonal pull would be required to do this because scientist say gravity is realitively weak?

Answer 1

Compression ratio is applicable to internal combustion engines. I'm not sure what you are referring to, here.

The question has long existed about whether the Universe is "open" or "closed." The answer is dependent on two factors, (your ratio?). One factor is gravity. The other is the expansion. The answer would also have to include an estimate of the size or overall density of the Universe. Given what can be observed so far, the mass is only about 1/100 what it needs to be in order to stop and reverse the expansion. I think this is why some people have been so eager to find some kind of "dark matter." I think they dislike the idea of unending expansion and "heat death."

I don't think they will find this dark matter.

But our estimate of the speed of expansion and the size and density of the Universe could be way off, as some other perspective could emerge on that issue.

Answer 2

I would like to point out that science can never hope to prove anything perfectly, merely prove things beyond reasonable doubt. But yes, the big-bang theory is the best and most likely theory for the universe as we know it today.

There is a quantity called a Schwarzchild Radius, which is proportional to an objects mass. If a sphere of a certain mass is compressed so that it spacial radius is less than its Schwarzchild radius, there is nothing stoping the object becoming a singularity. The Schwarzchild radius of an object can be found using the following formula, it is derived by letting the escape velocity of an object equal the speed of light:

R =2Gm/c^2

Where R is the Schwarzchild radius, G is the gravitational constant, m is the mass of the object and c is the speed of light in m/s.

It is impossible to know the mass of the universe since we cannot see it. However the mass and diameter of the visible universe [which is huge] is approximately:

1.4 * 10^10 Light Years in diameter or 1.3*10^26 Meters
3 *10^52 kg In mass

Remember these are just rough figures, no one knows for certain. Then the Schwarzchild radius of the visible universe is approximately 4.5*10^25 Meters

You will notice that these two radii are very close to each other [astronomically speaking, estimates of the mass of the visible universe differ by 7 orders of magnitude]. This is true, and it is something scientists are eager to find exactly. The mass of the universe is very close to a quantity known as 'critical mass'. If the universe is less than this mass, then everything in it will crunch back together again. If it is larger than this, everything will keep drifting apart for ever. Since experiments always have a margin of error, depending on which figures we use we are above or below this critical mass.

So really, we could already be doomed to form a black hole again.

Answer 3

Infinite, because a singularity has zero volume.

By the way, it is not conclusively proven that the universe began with all matter compressed into a mass smaller than the point of a needle. All we know for sure is that the present universe is expanding. The rest is a theoretical reconstruction that is resting on pretty shaky theoretical ground in some cases.

Answer 4

If you run the Universe backwards, so that it contracts rather than expands, the "classical" theory says that the density becomes infinite at time zero. BTW, this says nothing about the actual size of the Universe, which could be infinite at all times. The "smaller than the point of a needle" may refer to the material that is currently within our event horizion and is a small fraction of the total material in the Universe (perhaps even a finite fraction of an infinite amount).

Running the Universe backwards in this way, you get to a point a fraction of a second after the Big Bang where our current understanding of physics fails. Therefore, it may not become actually infinite in density, becuase of phenomena we do not understand.

But the classical answer to your question is "infinity".

Answer 5

The size of the universe now is estimated to be 7.3×10^26 meters, compared with a singularity size of 1.6×10^−35 m (Planck length). That's a compression ratio of about 4.6×10^61. Plus or minus a few factors of 10.

Answer 6

i am wondering the same thing.....