Stephen Hawking Describes the Universe Before the Big Bang

Sunday, 04 March 2018 - 11:06AM
Space
Astrophysics
Sunday, 04 March 2018 - 11:06AM
Stephen Hawking Describes the Universe Before the Big Bang
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Considering what little we know about the earliest moments of the universe, what happened before then is an even greater mystery.

But astronomers and astrophysicists can take what they know about how physics work and make some pretty educated explanations about what likely happened during, after, and also before the Big Bang jumpstarted the universe, which then expanded outward into the cosmic vastness of space we know today.

Enter world-famous theoretical physicist Stephen Hawking, who was asked about what came before the Big Bang by world-famous astrophysicist Neil deGrasse Tyson in a video from Popular Science. The first part of his answer is "Nothing was around before the Big Bang" - but before you say "well, there it is" and leave, he then gives a more in-depth explanation of why time and space couldn't exist (as we know it) before the Big Bang occurred.

See the full explanation below:



One of the reasons Hawking is so popular is how well he can explain complicated subjects; if he could brilliantly explain physics but only in complicated ways, he would only be popular among other physicists. So his explanation here, while not completely simple, is easy to follow as much as astrophysics can be, comparing the time-space continuum to a curved surface like the Earth.

He describes his "Euclidean" approach to the early universe:

Opening quote
"In this [approach], ordinary real time is replaced by imaginary time, which behaves like a fourth direction of space... The history of the universe in imaginary time is a four-dimensional curved surface, like the surface of the Earth, but with two more dimensions."
Closing quote


Hawking goes on to say:

Opening quote
"In order terms, the Euclidean space-time is a closed surface without end, like the surface of the Earth. One can regard imaginary and real time as beginning at the South Pole, which is a smooth point of space-time where the normal laws of physics hold. There is nothing south of the South Pole, so there was nothing around before the Big Bang."
Closing quote




Essentially, just like the way that "south" can't exist south of the South Pole because every southern direction leads to that point, time can't exist "before" the Big Bang, because this is the point that time and space are expanding outward from. Implying anything happened "before" the Big Bang is tricky when time doesn't really exist at that point.

There's still a lot to learn about the Big Bang, and a lot of competing hypotheses giving alternative origins for the universe, but it's a little easier when you don't have to worry about what happened beforehand.
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