Firstly, gan, can you explain:

(1) what you mean by anti-gravity.

According to the opinion expressed in Wikipedia:

"Anti-gravity is the idea of creating a place or object that is free from the force of gravity. It does not refer to the lack of weight under gravity experienced in free fall or orbit, nor to balancing the force of gravity with some other force, such as electromagnetism or aerodynamic lift."

(2) why you believe it.

"Time is what prevents everything from happening at once" - John Wheeler