Hey there. I feel like I'm losing my mind and could use your help. I was listening to this podcast: https://www.alieward.com/ologies/blackholetheorycosmology
Dr Ronald Gamble, Jr must know better than I do but it opened with two doozies of factual errors. First, that the Milky Way’s contents will fall into Sag A* (”over a million billion years, we're gonna fall into a black hole”) and within seconds that SMBs are “the only thing strong enough that can actually pull and hold a galaxy together.”
Am I insane or is this just wildly inaccurate? My understanding is that Sag A* is not predicted to consume the whole galaxy, and that as a very minor portion of the galaxy’s overall mass, can't be characterized as holding it together much less pulling it together. The mass of other light and dark matter is larger responsible for that.
Who is right?
by Ya_Got_GOT
2 Comments
Afaik, the two body problem decays *eventually* due to orbital energy leaking away in the form of gravitational waves. But since our galaxy is composed of trillions of bodies, it’s inaccurate to state that our SMB will absorb all the matter. It ignores the myriad other interactions which are already flinging stars out of the galaxy, and will continue to do so.
As far as holding the galaxy together, I agree that that’s also inaccurate. Though it’s likely the most massive object in our galaxy, its mass is a mere fraction, contributing to less than 0.0001% of the Milky Way’s total mass. Why it’s at the center is a matter of debate, but it is definitely not the only thing holding the Galaxy together.
If SagA poofed out of existence, the only part of the galaxy that would be significantly affected is the portion in very close proximity to the black hole. SagA’s gravity is basically irrelevant the sun’s orbit. We orbit the collective mass of the galaxy, which is far, far, far more massive than the black hole.