Carl Bjerknes demonstrated that pulsating spheres in water will repel or attract depending on their phase relative to each other. Since gravitation is a wave, why can’t this be used to create anti-gravity?

Question

https://www.annualreviews.org/doi/pdf/10.1146/annurev.fl.14.010182.000245?

> Vilhelm Bjerknes’ father, Carl Anton Bjerknes, was professor of mathematics at Norway’s only university in Oslo, or Christiania as the city was called at the time. He was exploring the forces between bodies moving in a fluid, and found a striking analogy between these forces and electrostatic and magnetic forces. In particular, he found that two spheres submerged in water, pulsating at the same frequency, would be acted upon by attractive or repellant pressure forces which would satisfy Coulomb’s law, except that they would have the opposite direction: attraction would result when the pulsations were in phase, repulsion when the phases were opposite.

Since it’s been experimentally demonstrated that gravity is indeed a wave, why can’t this same principle apply to gravity waves? In fact, unless all gravity waves must invariably be completely in phase, no matter what other circumstances may exist, then why aren’t there naturally occurring objects which repel each other through the action of gravity?

I’m led to understand that perhaps this has something to do with the difference between waves propagating through a medium and waves propagating through space. Is that correct? If so, then why? And by what mechanism does it work?

In: Physics

Answer 1

The fact that gravity is a wave doesn’t imply anti-gravity.

Electric charge occurs in both positive and negative values because matter has both positively and negatively particles.

Compare this to magnetism, there are no “north monopole” particles with only north magneticness. Magnetism is generated from moving electrons, but you always get north and south in equal amounts.

Gravity is a curvature of spacetime itself, and so far we have only discovered ways to bend it in one direction. In fact in E=mc^2 we see that both energy and mass are equivalent to each other. Both bend spacetime the same direction. Even antimatter bends it in the same direction.

To get anti-gravity, you need something that bends space the other way. While there is much unexplained: dark matter, dark energy, … none of that appears to have the necessary “negative mass” property.