# Thread: Explain this whole "Big Bang" thing to me

1. There is one angle to the "before the BB" that hasn't been explored here yet. Extending on Darkness's excellent wrap-up of the relativity theory, there is another factor that influences the passage of time, and that's mass, or rather mass concentration.

If a lot of mass is concentrated in one place, the passage of time is slower there. The more mass in one place, the slower.

As the Big Bang started, all the mass of the universe was concentrated into one infinitely small point. This means that the mass density was infinitely large. Which has the same effect on the stuff there as travelling at light speed: no time passes for the traveller/amassed one. Therefore, at least for whatever was at the place where the Big Bang happened, no time passed and the question of what was before lacks a reference. Before and after are a matter of time, and where no time passes, before has no meaning.

2. While a good explanation, the transforms in Darkness's post are a bit off. They should be Lorentz transforms.

*edit*
This doesn't really make a difference to the arguments, but for anyone interested in the mathematics of SR, a search of Lorentz transforms would be enlightening. Thats the only reason I posted this.

3. As the Big Bang started, all the mass of the universe was concentrated into one infinitely small point. This means that the mass density was infinitely large. Which has the same effect on the stuff there as travelling at light speed: no time passes for the traveller/amassed one. Therefore, at least for whatever was at the place where the Big Bang happened, no time passed and the question of what was before lacks a reference. Before and after are a matter of time, and where no time passes, before has no meaning
Einstein realized that same fact and had a very hard time agreeing with it...I read somewhere that the mass density was as big as several hundreds of thousands of tons per cubic inch amazing

4. the mass density was as big as several hundreds of thousands of tons per cubic inch
Didn't CornedBee just say it was probably infinite? You're off by about infinity

Therefore, at least for whatever was at the place where the Big Bang happened, no time passed and the question of what was before lacks a reference. Before and after are a matter of time, and where no time passes, before has no meaning.
Right, but that doesn't explain how it ever banged.

It reminds me of the good 'ol Achilles racing the hare paradox - the hare has a small headstart, and achilles runs at some speed faster than the hare. Achilles can never overtake the hare, because every time he gets to where the hare was, the hare has already moved on forward To resolve the paradox, you have to look from an external perspective and rather than considering each time frame that continually changes as the distance between them shrinks, you look at the steady progression of time as Achilles catches up and eventually overlaps the hare.

Unfortunately in this case we're saying that all space and time are shrunk to one point, and time from every point of reference in the universe is stuck. Logically then, we don't exist yet

5. But surely the Earth is bound because the Earth exist in 3 dimensions.
Perhaps not to an observer that exists in only 2 dimensions.
In that sense the universe might be 'infinite' to us, when it is not.

6. Originally Posted by Darkness
oh yeah, when you are going 30 miles per hour, here's what your passage of time looks like:

(670x10^6-30) / 670 x 10^6 = 1 - (30 / 670x10^6) = .999999955
No no no.
It is not linear.

If an object travels at speed v, the number you seek will be sqrt(1 - (v/c)^2).

EDIT: This means that for normal speeds, the difference is very small, but when you approach the speed of light, a change of speed of 30 km/h can mean a lot.