• How would we know a black hole is there if we can't see it?

    It would be pretty hard to tell for sure. We would see stars or planets being pulled toward a seemingly empty patch of space, which would mean that there is something heavy there. By measuring how hard the stars or planets are being pulled, we could figure out how heavy is the object doing the pulling. If it's heavy enough, and small enough, we would guess that it must be a black hole. We could be much more sure if we saw the gravitational waves coming from something falling into a black hole. These waves would show us very precisely what spacetime looks like near the place they were produced. Thus, gravitational waves give us a way to really "see" a black hole.

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Four Areas of Science


Come, you lost Atoms, to your Centre draw,
And be the Eternal Mirror that you saw:
Rays that have wander'd into Darkness wide,
Return and back into your Sun subside.

From Farid al-Din Attar's
twelfth-century masterpiece
The Conference of the Birds

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About SXS

The SXS project is a collaborative research effort involving multiple institutions. Our goal is the simulation of black holes and other extreme spacetimes to gain a better understanding of Relativity, and the physics of exotic objects in the distant cosmos.

The SXS project is supported by Canada Research Chairs, CFI, CIfAR, Compute Canada, Max Planck Society, NASA, NSERC, the NSF, Ontario MEDI, the Sherman Fairchild Foundation, and XSEDE.