How did round planets form from the explosion of the Big Bang?

Matter can be created --- from energy (indeed, one might think of matter as frozen energy).Now, you might ask what was the origin of the energy. That's an interesting question. One possible answer suggested by the inflationary hypothesis is that the net energy of the universe is zero. The simplest solutions to the equations that describe gravity (i.e. Einstein's equations of general relativity) require that the universe should either be expanding or shrinking. We happen to live in one which is expanding. Further to what other people have said, it's actually part of the definition of a planet that it should have enough gravity to make itself round. By a recent resolution of the International Astronomers' Union: It's hard to see what sort of confusion of ideas could lead someone to ask such a question.For now, let me point out that it was not an explosion and that it doesn't have a source.One analogy commonly used is that of blowing up a balloon. Imagine the two-dimensional surface of the balloon as an analog to our three-dimensional space. Points on the surface of the balloon get further away from one another, but there is no point on the surface of the balloon that can be considered the center of the expansion --- or, alternatively, any point on the surface of the balloon could be so regarded.

I was reading just the other day (I forget the reference, I'd have made a note of it if I'd known I would be participating in this thread) how the Earth can't possibly have mountains greater than a certain height (I think it was twelve miles).The point is that under sufficient stress rock will squash like plasticine. You can see this in the photograph below, which shows the effect of stress on cylinders of marble under various confining pressures. Rock that's buried under twelve miles of rock is under a lot of stress. Apparently, a mountain taller than twelve miles, under Earth gravity, would squish itself flatter than twelve miles high.I might have misremembered, it might be twelve kilometers, but you get the point.

I don't quite understand what you're trying to tell me. I said that matter is a form of energy --- on that I think we are in agreement.Perhaps you object to my use of the word "frozen". But all I meant by it was that, intuitively, matter coagulated out of the energy of the Big Bang when the energy density was low enough. I didn't mean to mislead anyone --- but is this not a good metaphor? If not, why not?

I think I see what you mean.Is this right? ---Matter is not energy.Mass is energy.If I'm right, please tell me what this means.

The world does not contain a big enough face or a big enough palm.For one thing, energy and force are measured in incompatible units. You might as well argue that "speed can be a distance". Read it yourself. Note that it does not equate force with energy. That's not even English, much less physics. Why would anyone even think that?

Wrong.Units of force: kg m s^-2Units of acceleration: m s^-2 Wrong.Units of acceleration: m s^-2Units of momentum: m s^-1 Wrong.Units of momentum: kg m s^-1Units of energy: kg m² s^-2 Right.Apart from that, you might as well be sitting there saying: "Distance is speed. Speed is time. Time is acceleration" for all the sense you're making. What is that meant to be an example of? A non sequitur?Edited by Dr Adequate, : No reason given.

Nothing, which is why it's in the "Big Bang and Cosmology" forum.It does, however, have something to do with creationism, since evolution isn't the only thing creationists are wrong about.

A couple of additions to your vocabulary.Firstly, the word "egg" refers to one of these things: Secondly, if someone was call you (for example) a deluded windbag with delusions of intelligence, that would not be an ad hominem argument. That would be an insult.