Why is there no such thing as negative gravity?
When Einstein came up with the theory of relativity, he figured he needed something like a negative gravity force to balance gravity so what he thought was a static universe could remain as it is. Later, when it was found the universe was expanding, and had a beginning, a big bang that started things off, the need for this Cosmological constant, which Einstein called the greatest blunder of his life, went away… Until more recent observation and theories have the most distant galaxies moving a wee bit fater that they should, so they must be pushed away by something, a kind of negative gravity. It is still only a conjecture; but this repulsive force would only act at great distance, and at short range, would totally disappear, would become unnoticeable compared with gravity. The jury is still out, and might remain out for quite some time on this one.
