Recent content by gregtomko

It sounds a little funny that at the beginning, expansion was super fast. Then during most of forever, expansion was close to linear; and just now expansion is speeding up again. I know that’s what the models say, but it seems like a pibtac

Thanks!

So you are saying that space was expanding so fast after the big bang, that a black hole was impossible?

The "big bang" as far as I understand, refers to a time when the universe was very small. It then expanded. When there is a high enough concentration of mass in our universe now, it becomes a black hole. Why is it that when all the mass was concentrated at or around the "big bang" did it not...

If the universe was at or near a singularity in the past, why is it not a black hole now? How can part of the universe become a black hole, and not the whole universe?

I know it is inconsequential, but how did the word "So" get placed at the beginning of the previously quoted text?

When the total damage is assessed for coal, every byproduct is gone after a few decades. In nuclear much of the hazardous waste isn't gone for tens of thousands of years. If spent fuel is safe today, how do you know it will be secure 100 years from now? Do you feel comfortable handing off...

Is radiation pressure and neutrinos a significant portion of the total energy output of stars, or most of it, or very little?

I think found part of the answer I was looking for. The gravitational binding energy of our sun is 6.9E41 J. The energy output at its current rate, if you average that over its lifetime, which is smaller than the total output, would be something like 4E46.

If the red shift data on the expansion of the universe was considered as the acceleration of the stars away from each other, is it known to any degree of accuracy, how much energy would be required to cause that acceleration? Just straight forward F=ma if it assumed that the stars are...

If the stars aren't actually accelerating away from each other, I can see how there would be no way to calculate the energy needed. That is definitely where my confusion arises. That was the whole basis of the question. Thanks so much for your input! I think you cleared this up.

Just the simple equation of F=ma. There is a mass of the universe. There is an acceleration of the universe. There can be an expected F on the universe. From that force, a quantity of energy needed to satisfy the F=ma relationship can be calculated.

I thought relativity excluded that possibility. Doesn't time skew as the rate of those galaxies separation increases?

What is the difference between objects gaining separation in space, and space expanding between objects?

I am asking about the energy needed to cause the acceleration of the expansion.