Ask Ethan: If gravity attracts, how does the ‘dipole repeller’ push the Milky Way?
Ethan Siegel

This is a really good indication of how gravity works, and it’s quite compelling evidence that the opposite of gravity is gravity. In this particular case, the opposite of gravity is less gravity.

To think about this, consider what would be necessary for a person at rest on the Earth’s surface to experience zero gravity. Another whole Earth, just touching their head! Alternative scenarios are possible involving exotic circumstances like black holes and such, but whatever they are, they must just exactly exert the same gravity as Earth, but in the opposite direction. This is the only anti-gravity we will ever see, at least if Einstein’s General Relativity Theory is correct: gravity in the opposite direction.

Worth thinking about.

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