What is time? Watch
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After coming to the knowledge that time began after the big bang, I have come to wonder what reality was like before time came into existence. Does anybody have a good explanation as to what 'time' is?
In human terms, time is observed by referencing events against two other rhythmic and repeatable events such as the movement of the hands of a clock, or in more precise ways, the two events are referenced against the wavelength of an electromagnetic wave emitted when an excited electron transitions (drops) between energy levels of a caesium-133 atom.
Since these definitions both rely on the speed of light (which Einstein said is a universal constant which cannot be exceeded), and that gravity can deflect electromagnetic waves (light), the observation of time and hence the occurrence of events may not be agreed for different observers of the same event but made in different gravitational fields.
Also, since gravity is a product of mass, at the Big Bang, all matter in the universe is concentrated into an infinitely small space (known as a singularity). The laws of physics and hence the language of physics (mathematics) as we know them, break down at this point because the singularity introduces infinity: infinite mass, infinite gravity, infinite energy etc. Our references for measuring time become meaningless.
Because of the infinity, matter and energy become meaningless, the four forces as we know them break down, and physics cannot deal with the consequences.
We are therefore currently constrained to say events before the Big Bang are meaningless, not because there are no events, (there may or may not be) but also because we have no way of observing or predicting anything before the Big Bang (if anything existed at all).
Time for us and the universe we live in therefore began at that instant and we are forced to speculate on what may or may not be the reality outside of our universe.