Question: In what percentage of a second did all the energy in the universe expand from one single point (the Big Bang)?

Jemma Rowlandson answered on 23 Jan 2017:

This is actually a very complicated question. Now we know that energy cannot be created or destroyed, it can only be transformed from one form to another. So with this is mind, that means all the energy that there will ever be in the entire Universe started in the Big Bang, along with everything else. And everything (including time) was created instantaneously. What happened in those first fractions of a second has been the subject of lots of research, both experimentally in a lab (by which I mean a massive particle smashing supercollider) and theoretically using equations.

There is something called Planck time, which is around 0.00000000000000000000000000000000000000000001 (that’s 43 zeroes, which can also be written as 1 x 10^-43) seconds after the Big Bang, this theoretically is the smallest possible unit of time we can observe. Before this, we cannot describe the Universe, everything is in the same, infinitely dense, incredibly hot point. Then things begin to separate, and shortly after that the Universe expands. This expansion begins at
0.0000000000000000000000000000000000001 seconds (36 zeroes or 1 x 10^-36). So that means the entire Universe, including all the energy in it, expanded at one undecillion-th or 1 x 10^-38% of a second.

An excellent timeline of the Big Bang by the way can be found here if you’re interested:

And a big thank you to Wikipedia, where these numbers came from 🙂
https://en.wikipedia.org/wiki/Inflation_(cosmology)