3 ms·
The yardstick is indeed the light-travel time. Gravitational waves really do change the time it takes for light to travel between two points. We use light trav
by ISL 3y ago
The yardstick is indeed the light-travel time.
Gravitational waves really do change the time it takes for light to travel between two points. We use light travel-times to measure distances, thus we say that the distance between the points has changed.
If it feels counterintuitive for spacetime to be changing, that's good. It is outside our human experience and perception. The strongest gravitational waves ever observed by scientists passed through everyone who was alive in 2015. None of those people noticed before the instruments registered a detection.
- truculent 3y agoThank you. If the yardstick is light-speed, is there any meaningful distinction between saying that space itself changed and that there are local perturbations to the speed of light? The thing I struggle with is that we normally think of things occupying space. If space itself gets distorted, then the size of those things should change, too. Or is that mental model a useful but ultimately incorrect way to think about the world?
- deleted 3y ago[deleted]
- jballanc 3y ago>None of those people noticed before the instruments registered a detection. IIRC, the reason no one noticed is that even the strongest gravitational waves are only going to "stretch" space by something less than the diameter of a hydrogen atom.
- MaxikCZ 3y agoCorrect me if I am wrong, the gravitational waves we measure have such small effect, that if we blew proton to the size of the Earth, it would get squished by distance smaller than a human hair. Edit: from wikipedia LIGO page: "(interferometers) are capable of detecting a change of less than one ten-thousandth the charge diameter of a proton" I dont know why I remember the human hair analogy, perhaps I am confusing it with something else?