Why does time not exist?

An interesting thought but a billion billion is meaningless to me, it is way beyond any number I can comphrehend. I like to play mental games to try and get a handle on big numbers, but even working out that a cubic kilometre contains a billion billion cubic millimetres doesn't help discern the enormity of the number

When does time not exist? When events don't happen.

Otherwise time is the rate at which individual actions occur.

The Quantum theory is derived from a science that claims that a single Big Bang happened by magic from nothing though.

I prefer a sound scientific explanation myself, not a science that relies on magic because it can’t explain the primary energy source which caused its single big bang.