Uploaded on February 19, 2016
Gravitational waves explained by astronaut David Saint-Jacques2016-02-19 - What are gravitational waves?
CSA astronaut David Saint-Jacques explains the historic detection of gravitational waves that was announced last week.
(Credits: Canadian Space Agency, JPL-Caltech, NASA, LIGO Scientific Collaboration, Massachusetts Institute of Technology (MIT))
David Saint-Jacques: Ever since about 100 years ago when Albert Einstein wrote his theory of relativity, we’ve been suspecting that if things like massive black holes at the other edge of the universe were to collide with each other, that would be such a dramatic massive event that it would send ripples through space-time itself. Gravity would kind of stretch space and this wave of stretching would reach us.
It’s a bit as if we were here on a beach somewhere in North America wondering: Could we sense it if somewhere in Europe a cliff collapsed into the ocean? The waves of that event, would they reach us across the Atlantic?
We’ve been trying to do that with gravity waves, and it has not been possible for decades and decades. We made the calculations so we have two masses. They are a couple of kilometres apart. We keep them very stable and if the gravity waves go through them, it will make them move by a fraction of one atom. A small fraction of one atom. A very small movement.
It took decades and finally, we got the first little signal of very faint waves attenuated by travel through the universe that went through the Earth, made those little masses move and we got the signal.
We just heard a very faint echo of this crazy dance of two black holes colliding with each other at the other edge of the universe more than a billion years ago, and we can sense it here on Earth.
It’s just amazing. We just literally opened a new window on the universe.
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