(Not a professional physicist.)
My understanding is that we have a very good model for how gravity should work, and we’ve used that model to predict a lot of things we can observe. A few I can think of offhand:
- Light bending. We’ve taken many telescope readings through their general neighborhoods. In each case, we see the distortion and optical effects we would expect from our model. (A similar experiment is what really cemented relativity as accurate iirc.)
- We do have a photo of a black hole, and it looks as we would expect (accretion disk included!). It would be difficult to explain the torn apart hyper-accelerated cloud of atoms around the black hole if the black hole didn’t tear things apart.
- There are computational models for galaxy formation and trajectory. My understanding is that (modulo dark energy/matter), these models match what we see reasonably well. I think the galaxies we see would be quite different if black holes never fed on matter (they would be much smaller, for example).
Physic student here, so not a full professional yet.
I just wanted to add to this nice explanation that using the models of how we expect gravity to behave, we theorized the existence of black holes way before observing them. And not just black holes, but many other observations about the nature of our universe were theorized before we saw them. Like light bending.
That’s how good the math was, that the models keep proving to be accurate as we observe more of our universe. I find that so cool :)
And most of the math was from Einstein. No wonder he was that famous already during his lifetime and his name became synonymous with intelligence. Some of his predictions only got experimentally proven recently (gravitational waves).
Also, just to add to this. Regarding point one, photos of the stars taken during a total eclipse show shifts in position consistent with their light being bent by the relatively modest mass of our own sun.
Albert Einstein‘s general relativity theory of gravity includes black holes. Black holes are basically where this theory of gravity breaks down, also known as a singularity.
The mathematical model describes gravity extremely well and has been proven to be correctly describe and predict our observations of the cosmos.
You can look into the models behind it. To really understand physics beyond vague descriptions, you need to understand the math that describes it.
This MIT class on General Relativity includes 23 video lectures. The first 9 lectures explain the mathematics, black holes are described in the last two.
Found these other two lectures, which are newer and easier to digest.
https://www.youtube.com/watch?v=HnNJoZneAYI
https://www.youtube.com/watch?v=S0xznDbhl8U
Having at least a vague idea of the mathematics supporting this, helps enormously to understand this.
This is an advanced topic, so give yourself some time to learn.
Edit: found a friendly and cheerful guy on YouTube explaining it as well. https://www.youtube.com/watch?v=nB83RgE8xRg&list=PLeoh1MW56PeLn-tYxepNXBnfTMdbBemfJ&index=28
Edit2: disregard the above, watch this https://www.youtube.com/watch?v=Zch54CVfaK0 https://www.youtube.com/watch?v=XlHhmrnGw2k if you want only minimum amount of math.
Well there goes my week…thanks!
You can find videos of an active black hole:
You cannot “see” the black hole directly, but you can see the stars orbiting the black hole and the effect of gravitational lensing.
In a similar way when you see your own hands, are aren’t really seeing your hands, but the photons bouncing off your hands into your retina.
Such a cool video! Apparently it’s a time lapse taken over 20 years.
It takes our solar system 225 MILLION years to orbit the black hole in the centre of the milky way galaxy.
Black holes aren’t the only objects capable of tearing things apart with their mass. Neutron stars, for example, are more than capable of tearing apart objects that pass nearby. Even planets. We’ve seen Jupiter tear apart passing asteroids.
Math and observation.
Before we finally found one in reality, we just had math telling us what to look for.
Math also suggests the possible existende of the opposite of a blackhole; a white hole. Where matter is constantly being ejected instead of vaccuumed up. We have yet to find one of these, tho.
Well for one Einsteins general relativity equations predicted the possibility of black holes before we ever found any!
Math.
I came here to say this. It is the most elegant reply.
