Iamon_lyme: Extreme gravity and the fact that atoms are basically alot of empty space. If blown up an atom would have the nucleus the size of a ball while the electrons would be circulating at say 100 metres distance. Of the main forces in the physical plane.. gravity at the moment is a weak force, it's how come magnets can pick up metal. Yet at the time of the Big Bang, gravity was millions/billions/infinitely times strongly. It seems gravity at the moment 'leaks' into one of the strange new dimensions they are now finding thanks to atom smashers. With enough mass (like a black hole) gravity has enough force to compress matter and through that, bend space and time unlike anything in normal space.

An example of bending space... our Earth's gravitational effect compared to 'zero g' causes enough difference in time that the atomic clocks used in the GPS satellites have to corrected every day by earth based atomic clocks or they would be 10's of miles out.. just from the bending effect difference of zero g and 'one g'.

Another example would be that light takes just minutes to travel from the surface of the Sun to Earth, yet through gravity and other forces takes 10's/100's of thousands of years to reach the surface.