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Gravitation force is always attractive.

Now assume(not a practical one): I took our Earth in my hand and started shaking up and down. This will create a disturbance in space-time warp and it moves like a wave outward direction. So when the crest part of this disturbance comes in touch with another mass, it should carry that mass with it and start moving away from Earth. It was visible because I used a very massive object like Earth. Though it is not visible it should be true with low mass objects too? So is gravitation field is always attractive?

Kitchi
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2 Answers2

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That's a very interesting question.

The short of it is that Gravity is always attractive.

When you imagine a gravitational wave (GW) going by, its not like the gravity is pushing and pulling on the object, its like it pulling-less, and pulling-more. By analogy its a lot like the tides. There is a tidal bulge on the side of the earth opposite the moon, not because the moon is pushing that part away from it, but because its just being pulled less than the earth itself.

DilithiumMatrix
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Gravitational waves (or electromagnetic waves) are not like water waves, in that they have only transverse modes and not longitudinal ones. This is related to the fact that these waves travel at the speed of light.

Contrary to zhermes' answer, gravitational waves do not push or pull objects in their directon of motion. Instead they stretch or compress along axes perpendicular to their motion. Here is Wikipedia's illustration of what a gravitational wave coming out of the screen might do:

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