Well, what we know about gravity is what Albert Einstein summarized in his theory of generativity.
[0:57:19 - 0:57:26] ▶
And according to Einstein, it's possible to get an effect of repulsive gravity if the vacuum itself has some mass density.
[0:58:27 - 0:58:37] ▶
That's called, that was termed by Einstein, the cosmological constant.
[0:58:37 - 0:58:42] ▶
Anyway, this is just one example of a situation where gravity follows Einstein's theory, except that there is some new ingredient, like negative mass.
[1:01:10 - 1:01:20] ▶
Somehow it will be prevented now. One idea that was suggested already by Einstein and Rosen, Nathan Rosen, his postdoc back in the 1930s was maybe you can build a bridge that will connect different regions of space and traverse the distance through a sort of a tunnel, a wormhole.
[1:02:43 - 1:03:08] ▶
So at any event, they came up with a solution of a wormhole, but then it was founded such a solution is not stable within Einstein's theory of gravity.
[1:03:28 - 1:03:39] ▶