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Hello Janna, thanks for doing this.
I remember reading years ago about a possible black hole scenario:
A rotating black hole would increase its rotational speed as the mass collapsed further in on itself because of conservation of angular momentum, therefore some of the exterior mass would reach "escape velocity?" and would form a ring around the collapsing black hole. If I remember correctly, the overall mass of the black hole would cause a gravitational field that is survivable (no spaghettification) and could be used to either see the other side of the black hole or propel a spaceship to relativistic speeds.
Am I remembering complete gibberish, or is this a plausible cosmic scenario for black holes?
**EDIT:** I believe she replied elsewhere, I'll paste her response here:
Lots of interesting ideas here. A rotating black does twist spacetime like a tornado so that material gets caught in the whirlwind, like cows and trucks and dirt all get swirled around with tornados. Even if you have no angular momentum you will get dragged around the hole and likely fall in. If you have some angular momentum of your own, then yes you could be cast into a swirling disk around the black hole. And many black holes do have bright accretion disks where the matter slowly dribbles in. Think Interstellar. That black hole was very accurately represented with a swirling disk. Separate idea: the bigger the black hole, the more easily you will survive transit through the event horizon and you won’t be speghettified until you’re crushed to death inside the black hole. It’s harder to stand on a basketball (a small sphere) than the Earth (a huge sphere). Perhaps counter intuitively, you notice the curvature less and less the smaller you are compared to the size of the event horizon. All black holes, rotating or not, allow you to see behind them because even light travels along the curved spacetime. If you were to shine a flashlight directly “behind” (can’t say which is the front or the back) a black hole, some of the light will fall in, some will spray out and its path will curve around the black hole so that those standing on the other side will see your flashlight. The lesson: Don’t hide behind a black hole. They can still see you.
**EDIT 2:** To expand on the question as u/WholeLot pointed out, I was apparently referring to a ring singularity or Kerr ring. Anything you'd like to add here Janna regarding this ring singularity or Kerr ring?
Is it possible our understanding of black holes is flawed? What are some possible ways we might be misinterpreting the reality of the situation?
NDT brought up an interesting point on [The Late Show recently](https://youtu.be/TgA2y-Bgi3c
) about how the universe will/is expanding beyond the horizon. Do you think we've actually already lost cosmic information previously available to us or is this like a billions and billions of years from now kind of thing?
Thanks for taking the time for this AMA!
After watching Nova the other night, the early development of black holes in the young universe seems to have been critical for the establishment of galaxies. This early universe was a smaller place due to the expansion of the universe, could super-massive black hole has been formed by black hole combining in a smaller volume of universe? If so, what would the effects of the gravitational waves generated be on the structure of galaxies? It's a simple, and inaccurate analogy, but if you watch the surface of a pond, small floating bits of leaves and what not tend to be driven together by the motion of the surface. Would these gravitational waves actually empart force on matter?
With the size of Sagittarius A what kind of star or other event is capable of creating such a large black hole? Or did it simply absorb enough mass to obtain its size? And how long would it take something of its size to fizzle out due to Hawking radiation?
What advances in science do you see being made within the next ten years?
It has been said that the directions of space and time “reverse” within the event horizon of a black hole - the singularity effectively becomes your unavoidable “future”. Does this mean that there is some degree of freedom to move through time or receive information from the future in the moments before you reach the singularity? I’m assuming a really huge black hole where tidal forces may be survivable near the event horizon?
Saw Nova on Wednesday. Entire family enjoyed it.
Is it possible that our entire galaxy or even the observable universe is inside the event horizon of a gigantic super massive black hole? How can we detect that this is or is not the case?
For such a large black hole, is it possible that objects can escape out of its event horizon through cosmic expansion of space?
I was confused by some data related to LIGO's observations of gravitational waves. Say you have two black holes, each weighing 20 Solar masses. They merge together, the resulting black holes weighs say 30 Solar masses, while 10 were radiated away as energy of gravitational waves. Now, if nothing can leave black holes, how was that huge amount energy able to leave them anyway?
I watched your Nova episode, and it was fantastic! Your hosting was excellent.
In the special, it is mentioned that there is a limit to how much material a supermassive black hole can consume in a period of time, due to the photonic pressure of the light emitted by the accretion disk. Does this mean that quasars would actually be *more* bright if this limit did not exist? Also, would this not suggest that many quasars would be of equal brightness, since they have reached this limit?
My second question is this: It is mentioned that inside the event horizon, an observer (the astronaut who got e't by the black hole) would see the entire future of the universe play out due to time dilation. However, give the funky things that black holes do to the path of light in the vicinity of the event horizon, would the geometry of space-time allow the light entering the black hole to even be coherent enough to extract such an image, let alone see it with one's eyes? I know there is a lot of talk about information being consumed by black holes, but is that information in any kind of coherent form once it is inside the black hole?
This may be a silly, simplistic question with a difficult answer... But what is the current theory for what's in / on the other side of a black hole?
Can we create mini black holes and use them for technology? Are there certain attributes limiting the mini black holes we create from being usable?
In your opinion, When do you think technology will be advanced enough for humans to capture images or footage of an actual black hole?
How does an actual work day look like for a person in your position ? is it mostly meetings and coordination ? or do you crunch numbers over an excel sheet ? do you calibrate and finetune your devices ?
Have you seen the movie "interstellar?" How realistic is the halo of light around the black hole in the movie? Also, if "white holes" do exist, what is their relation to black hole and how would they affect spacetime, compared to a black hole?
If Black Holes are “rips” in space time, at the Planck length, what is on the other side of space time?
Hey there, thanks for the AMA!
What is the best way for someone who just has a basic understanding of physics to get into astrophysics and understand the universe a bit more ? Can you recommend any series, youtube series or book series that explain things in a simple yet interesting and detailed way ? Could you recommend something for my 11 year old sister as well?