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Comment by bahro | Hacker News Reader

To be clear, this article is about gravity waves (https://en.wikipedia.org/wiki/Gravity_wave), or ripples at the interface of two media of different densities caused by gravity, such as waves on the ocean or ridges of clouds, not gravitational waves (https://en.wikipedia.org/wiki/Gravitational_wave), the propagating ripples in spacetime.

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With the LIGO discoveries last year I thought about gravitational waves too. Having such a wave having effects visible with the naked eye would be huge. It would probably rip the planet apart.

Important distinction, +1 for linking to the wikipedia articles!

Confusing terminology. I say the scientific community should rename "gravity" waves to "buoyancy" waves, which is more specific and accurate.

Gravity waves aren't caused by gravity, they are in the direction of the gravitational force.

Sure they are. Some of the denser fluid is above the average level of the surface, and gravity pulls it back down again. That's what makes the wave.

Gravity is one of several forces that may act on what's going on, but the cause of the wave is the initial perturbation, which isn't gravity. Put another way, if I have a steady-state hydrostatic system, gravity waves won't just spring into existence. You need that initial push.

In this case, the initial push seems to be wind hitting a mountain and being forced up.

You need the medium, gravity, and 'push' to get a wave. Calling them <medium>-wave, or 'push'-wave doesn't really tell you anything useful, so they're called gravity-waves. An alternative would have been buoyancy-wave, but apparently this didn't catch on (buoyancy and gravity are really two sides of the same coin, anyway).

Buoyancy is related to density, which is independent of gravity. Check: buoyancy can exist in a non-inertial reference frame provided acceleration in a "downward" direction.

Also, you don't need gravity to be the force being acted against in order to form a wave. You can get impact waves in water at 0g because of surface tension.

https://en.m.wikipedia.org/wiki/Buoyancy

> gravity waves won't just spring into existence. You need that initial push.

The gravity wave that causes tides on Earth requires no such push, it's just straight up deformation of the oceans by Lunar and Solar gravity.

> In this case, the initial push seems to be wind hitting a mountain and being forced up.

Where did you get that from, the body of the article? It's not in the abstract, which only talks about gravitational effects.

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