Whether their exist an anti-gravity element?

Answer 1

Probably not.

In quantum field theory the graviton is a hypothetical massless particle which mediates the force of gravity. In other words, its conjectured that gravity is transmitted between bodies via or by gravitons. There is no experimental evidence for the existence of gravitons.

The graviton idea was invented partly because it was discovered that gravity isn't instantaneous (something which Newton believed) but propagates at the speed of light, and therefore needs some kind of carrier (a bit like the photon and light).

To postulate an anti-graviton is to postulate anti-gravity. No such thing as anti-gravity has been observed. And even if anti-gravity did exist, it would fit with quantum field theory if it were mediated by the graviton.

P.Embleton

Answer 2

As of current scientific understanding, there is no evidence of an anti-gravity element or substance that can defy the laws of physics and create anti-gravity effects. Gravity is a fundamental force in the universe that is always attractive and cannot be negated with a single element.