# Do gravitational waves affect the flow rate of time?

Since LIGO has been able to detect the presence of gravitational waves, this implies that there is a density wave traveling through space with a high potential front and a low potential back side. Since gravity affects the amount of time that passes relative to an outside observer, do gravitational waves minutely slow/down speed up time when they travel across a region of space?

I'm also interested in learning if waves in the fabric of space time are strictly the same thing as the gravitational force being expressed as a wave. You can create a wave in a pond by throwing a rock, similar to black hole collisions. But, that doesn't necessarily mean gravity is itself a wave.

• yes, they are perturbations to the spacetime metric, so they can cause length and time perturbations. – Bobak Hashemi Feb 24 at 21:45
• Gravity doesn't cause time dilation. It is time dilation that causes gravity. – safesphere Feb 25 at 9:56

Gravitational waves are propagating wavelike metric perturbations in the Riemannian geometry of spacetime. The simplest ones, plane waves, are transverse. If they propagate in the $$z$$ direction, they affect spacetime intervals in the $$x$$ and $$y$$ directions (they squeeze $$x$$ while stretching $$y$$, then vice versa, then repeat), but they do not affect spacetime intervals in the $$z$$ and $$t$$ directions. So they don’t cause time dilation. Even if they did, the weak plane waves LIGO detects from far-distant sources perturb the metric of spacetime only at the level of one part in a billion trillion.