Is there a theory about anti-gravity

Antigravity

Term for a force or a phenomenon that counteracts gravity. The theories of gravity, such as Newton's theory and in itself also the theory of relativity, say nothing about the existence of antigravity. In the core one cannot shield the gravitational force, because there is only one form of 'gravitational charges' which Dimensions. In electrodynamics, on the other hand, it is possible to shield the electrical forces when positive charges meet negative charges. In relativity there is'no negative rest mass'!

How does that work?

At least hypothetically there are particles with imaginary masswho have favourited tachyons. These particles move at speeds greater than the speed of light (what is called super-relativistic could denote) and thus violate the fundamental in physics Causality principle: Cause and effect can be interchanged when tachyons are conveyed. Physicists try to avoid this and are extremely skeptical of theories that spawn tachyons.

A little less crazy please ...

However, there is a mysterious force that is decisive for the development of the universe and that could be described as antigravity: the Dark energy. So it counteracts gravityrepulsive and fundamentally different from matter. In principle, Einstein introduced it when he applied his general theory of relativity to cosmology in 1917. From a mathematical point of view, he wanted something that was aesthetic static universe justify. However, this was only possible if he introduced another term in his field equations that suppressed the dynamics: theLambda term or also called cosmological constant. A positive cosmological constant now has a repulsive effect and is accordingly an antagonist to (attractive) Gravity.

Expansion of the universe is anti-gravitational

With the discovery of the expansion of the universe, the cosmological constant was dropped and was long forgotten until it was again in the 90s en vogue was used to explain cosmological data. Now, in 2004, the cosmological constant is even favored by supernova (type Ia) because no noticeable temporal variability of dark energy could be demonstrated (Riess et al. 2004, astro-ph / 0402512, HST observations).
In cosmology you can still find models with positive cosmological constants, even more: the current measurements support the thesis that we are in one Lambda-dominated universe Life. The proportion of dark energy is even the decisive proportion with 2/3.
It is also believed that a bubble of dark energy, a 'Anti-gravity vacuum'are realized inside new solutions of the Einstein equations, which have been called gravastars. The anti-gravity vacuum stabilizes the Gravastern and prevents its collapse. They are now called regular Alternative to the black holes discussed.