STORY – These very large gravitational waves are emitted by the mergers of supermassive black holes.
This is Albert Einstein’s great discovery: the Universe is not simply the sum of the objects that compose it. It has an underlying structure, the famous space-time, which is both plastic and dynamic. Its best known property is to be deformed by mass. Popularizers readily use a two-dimensional analogy to get an idea of this: that of a stretched sheet on which more or less heavy objects are placed, which then form basins. This makes it possible to instinctively understand why a ball thrown straight on the sheet will naturally be deflected from its trajectory by a massive object. In Einstein’s vision, the object goes straight, it is the space in which it evolves which is deformed and modifies its apparent direction.
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But this is not the only consequence of the theory of general relativity. There are at least two others: space-time evolves (it is in accelerated expansion which leads all objects to move away from each other…