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

Hello Aptera and welcome to the Forum Really? How does one calculate the probability of God? I didn't choose to "believe in evolution" any more than I "choose" to believe in gravity, or the first law of thermodynamics. I'm convinced by the overwhelming evidence in favour of these scientific findings. The theory of evolution deals only with the changes that occur in biological populations, it does not approach the topic of how planets or the universe came to be. You're thinking of astrophysics and cosmology, according to these areas of scientific investigation, the universe was indeed much smaller than it was now 13.7 billion years ago, however there is no time at which it was infinitely dense, etc. - the physics we know can't cope with that, so although it's a logical conclusion, Big Bang theory only goes back to about one trillion trillion trillionth of a second after this hypothetical point. Secondly, the theory does not require that this be the origin of the universe - although that's how it's often construed. We don't know. It may not have "come from" anything, it may have been spontaneously generated. It may have been formed by a process beyond our universe. They may have been a big crunch, followed by a big bang. The answer is beyond our knowledge.Matter, by the way, can be both created and destroyed; you're thinking of energy - but that too can be created and destroyed according to Quantum Mechanics and does so constantly at the subatomic level. Regardless, the first law of thermodynamics applies to things within our universe, attempting to apply it to the universe itself is a logical fallacy. It didn't "explode", the Big Bang is not an explosion. Thinking of it as an explosion will not help you understand it. As far why there was the expansion - I don't know, I don't think anyone does? It wasn't round, they became round later, because trillions upon trillions of little bits of matter accumulated under their own gravity. Spherical objects are physically stable because they minimise the overal gravitational effect, similarly to why water droplets form spheres (here, it is atmospheric pressure and electrostatic attraction that is responsible but the principle is the same). The "explosion" was everywhere. Every point, everywhere in the universe, is where the big bang was.

This is wrong, expansion is not about size it's about the distance between points.As a simple mathematical analogy consider the function f(x) = 1.5x, evaluated across the real entire number line. If you take any two point on the line, they end up further apart after the transformation, yet the space convered by the output is the same infinite size as the original space.

Sasuke is right, when you eat you turn matter into energy. Some of the mass is converted into heat.(Although, to clarify, he's wrong about the other stuff)Edited by Mr Jack, : No reason given.

Yes, it is. That changes the mass. Burn something, capture all the gasses, keep all the ash and weigh it. It will have lost mass. The mass it has lost will exactly match the energy of the heat as per Einstein's equality.

Sorry, I'm clearly not using matter in the refined way you are. I meant simply that the mass of the solid stuff drops as it's converted to energy useful to the body. Heat has mass? I didn't know that. Although, thinking about it - it makes perfect sense.