[ExI] The biggest black hole merger ever detected so far rocked the Universe

[BillK]

The biggest black hole merger ever detected so far rocked the Universe
The gravitational waves they emitted were fiercely powerful, but where
did the black holes come from?
Philip Plait     July 14, 2025

<https://badastronomy.beehiiv.com/p/the-biggest-black-hole-merger-ever-detected-so-far-rocked-the-universe-dc6b8bba789d58bd>
Quote:
In the last few orbits before they merge, taking just a fraction of a
second, they create a blast of waves that can be incredibly powerful.
These waves march across the Universe, and flow over Earth.
When that happens, spacetime itself contracts and expands.
The effect is small; over an object the size of Earth the stretching
is only a few times the size of a proton!
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But LIGO can detect it.  Isn't science marvellous?
BillK