# Tag Info

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Physics generates theories that predict the behavior of the universe, and confirms or contradicts those theories with experiment. Physics ends where these activities do not work. There is no mainstream theory of God in physics. Nobody has been able to do any reproducible experiment that demonstrates the existence or non-existence of God, or that relates ...

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In modern theoretical physics you can actually look back to a point in which they call "inflation" which is just 6.36 x 10^-34 of a second, i.e. the Planck Time, after the bang. The moment just when "our time" starts up, or comes into being if that makes sense. We are pretty sure about 300,000 after the big bang the universe was so hot the leftover heat is ...

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You start from the (special) relativistic expression for energy: $$E=\sqrt{m^2c^4+p^2c^2}$$ Now, if the first term is much larger than the second ($mc^2\gg kT$ or $v\ll c$), we should take this first term out of the square root and taylor expand the (then in standard form) rest, discarding all but the leading term: ...

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I believe that this result only holds for $v\ll c$. Having assumed this, lets start: $$Total Energy = Rest Energy + Kinetic Energy$$ Keep in mind that since $v\ll c$, $c^2$ is the energy to mass conversion ratio and $K.E.=\frac{p^2}{2m}$ $$E=Mc^2+\frac{p^2}{2m}$$ There!

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The definition of entropy is $$S = -k \log(\Omega),$$ where Omega is roughly the number of microstates (ways of ordering your particles) compatible with the macrostate (what you observe macroscopically). Intuitively, you can say that, if you have particles inside a box, and you increase the size of the box, you can arrange them in more ways; therefore, the ...

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There is a three dimensional shell of galaxies (none currently observed) that have a gravitational redshift relative to us that is consistent with a relative motion at the speed of light. If you moved to any other galaxy in the universe, there is a very high probability that they would observe a different such bubble. If you look sufficiently far into ...

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This is an experimental physicist's answer: The linked article is careful to state: That means that conservation of energy can appear to be violated, but only for small values of t (time) Italics mine. Conservation of energy is an experimental fact that has been validated in innumerable experiments. This means, as far as the correspondence with ...

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My answer to your question is: no one can reliably answer your question. The model of the universe based solely on General Relativity says something about the beginning of the universe. If one follows the evolution of the universe backwards in time, one finds a singularity of infinite energy density "before" which the concept of time has no meaning. ...

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Black Holes and Big Bang seed are both singularity (and, may look similar), but they are fully different. Black Hole is singularity in Time (meaning, at singularity, space component from Spacetime vanishes and if you fall inside a Black Hole, singularity would be in your direct future), but Big Bang seed is singularity in Space (in rough words; Big Bang seed ...

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I'm no expert on the subject, but according to one of the proponents of this model (http://wwwphy.princeton.edu/~steinh/npr/), the 2 branes "stick" to create the universe. Hope that helps.

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There are various theories about how the matter anti-matter asymmetry arose. See this search for lots of related questions. It's generally believed that the Big Bang formed almost equal quantities of matter and anti-matter, but there was a very small inbalance i.e. there was slightly more matter. The anti-matter all annihilated with matter to leave normal ...

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Regarding the meaning of "universe": Unqualified, the Universe is all there is, was, and will be. In other words, there is nothing that is outside of, independent of, stands apart from, the Universe. The Universe is commonly defined as the totality of existence However, it is often the case that "universe" is short for "observable universe": The ...

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Gravity has played a dominant role in the development of the large-scale structure of our universe. The largest structures of matter in our universe (most of it dark matter) grew out of over-densities in the primordial matter distribution that emerged shortly after the big bang. Dense areas began collapsing under their own gravity, and over time as their ...

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