Fredric Pohl scifi fans might enjoy Hechee Rendesvous, which is near the end of the Gateway series. Somone finds a way to live inside both Kugelblitzen and black holes I think.
Eldar Black Holes
61–70 of 166 posts
Re: Eldar Black Holes
#62Reminds me a bit of the old short story The Crystal Spheres. In that universe, once a civilization had attained a certain level of advancement, they intentionally migrated to a black hole to await the arrival of others (the idea being that all advanced civilizations in the universe were separated by so much time , that they suffered from a sort of loneliness). https://en.wikipedia.org/wiki/The_Crystal_Spheres
There's another book whose name is on the tip of my tongue that has a similar premise, except the planet instead of the entire system is encased in a sort of time-dilation field. Naturally, humanity thinks it's an attack.
Re: Eldar Black Holes
#63Earlier quoted context omitted.
A traveler can reach it all right, but only from his own point of view. From the point of view of almost everyone else in the Universe, including us on Earth, it will never ever reach it. It's like the traveler has jumped into an other universe "located" in an infinitely distant future.
So let's say I fall into a black hole. And then four billion years later, someone else falls into a black hole from the same direction. From an outside perspective at a point nearly infinitely far away in time, we would seem to slow until we are right next to each other at the event horizon, correct? Does this mean everything that falls into a black hole crosses the event horizon (from their perspective) at the same…
Yup, from an outside perspective you simply cannot see something cross the event horizon no matter how long you wait, except by detecting the added mass.
Re: Eldar Black Holes
#64This was a major theme in the 'three body problem' book series.
There's a similar civilisation in "Revelation Space" which I really recommend.
Re: Eldar Black Holes
#65Earlier quoted context omitted.
That's the thing that never made sense to me about the black holes. The closer you are to the event horizon, the faster the time passes for the universe around you. So reaching the event horizon should take infinite amount of the "outside time", so right before you reach the horizon, you should see the whole future of the universe, including its end, if there's any. So how do black holes gain any mass then?
There are two frames of reference here, and only from the frame of the external observer does what you say hold true. From the point of view of infalling mass, there is no “freeze-frame” and time proceeds normally. The classic example to illustrate this is a black hole with so much mass that you can fall past the event horizon without experiencing significant tidal forces. You could survive the fall, Andy live for ho…
But from our perspective, the outside observers, why do black holes gain mass? It would take an infinite amount of time from our perspective for any mass to even touch the event horizon.
Re: Eldar Black Holes
#66Earlier quoted context omitted.
You have almost formulated the no-hair theorem. https://en.wikipedia.org/wiki/No-hair_theorem
I never thought of that in the context of strangeness, lepton number, and other conserved quantities. I don't think strangeness is really measurable (and I don't remember if it's technically conserved), but black holes should probably preserve lepton number somehow. Is that a quantum gravity sort of problem?
It might be, in that a Q-ball or something similar could there instead of a singularity, or it could be that there is no interior. Remember that the Holographic Principle implies that the total entropy of the volume of the hole can be encoded in the 2D event horizon of the hole.
The singularity is a prediction of GTR, but GTR breaks down there too. This is why black holes are so exciting in the context of new theories which are complementary to GTR!
Re: Eldar Black Holes
#67Earlier quoted context omitted.
There are two frames of reference here, and only from the frame of the external observer does what you say hold true. From the point of view of infalling mass, there is no “freeze-frame” and time proceeds normally. The classic example to illustrate this is a black hole with so much mass that you can fall past the event horizon without experiencing significant tidal forces. You could survive the fall, Andy live for ho…
But from our perspective, the outside observers, why do black holes gain mass? It would take an infinite amount of time from our perspective for any mass to even touch the event horizon.
At this point a few issues arise. The first is that what you’re describing is a feature of the Schwarzschild metric, which applies to a model black hole, which is time-independent and eternal. There is no particular reason to believe that this accurately describes black holes in nature. For example this metric can not describe the merger of two black holes, but we now have observational evidence that this does indeed take place.
The biggest issue, aside from the model, is that time dilation is something which only matters when two observers “compare clocks.” Neither observer alone ever experiences a difference. The crew of a 99.9% lightspeed ship doesn’t experience time dilation... until they return home. It makes no sense to talk about the effects of time dilation from the point of view of a one-way trip to the event horizon.
Re: Eldar Black Holes
#68There is a fascinating PBS Space Time video[1] about black holes that questions the very existence of whatever is "inside" a black hole. They point out that as you approach a black hole, your proper time is advancing slower and slower when compared to an observer located far away from the black hole (like us, on Earth). That means that from the point of view of this far observer, nothing happens inside a black hole u…
off-topic a bit: does anyone have suggestions for paths for the layperson toward being able to reason and intuit about this stuff at one level beyond pop physics claptrap? I have heard "the theoretical minimum" suggested in the past, but I haven't heard from anyone who has actually used it to go from zero to say, general relativity, only people who think it sounds good. It also seems like a steep investment -- I just…
Start with YouTube -- "Crash Course Astronomy" and then "PBS space time". Both programs are very well done, and give fairly rigorous yet entertaining overviews to cosmology and the related physics (PBS space time is the more rigorous one). Crash course is great because it touches on almost all major cosmological phenomena. For some of the videos, you may want to rewatch certain parts for understanding, or supplement with some brief research via google.
This route provides a gentle, productive ramp as you make sure you really want to dive deep.
I've done that and, ideally, I'd like to now buy some college physics books. However, I may have to delay this next step for quite a while due to some other higher priority goals... We will see if I get back to it. There is too much interesting shit and important things to do in the world, heh.
Re: Eldar Black Holes
#69There is a fascinating PBS Space Time video[1] about black holes that questions the very existence of whatever is "inside" a black hole. They point out that as you approach a black hole, your proper time is advancing slower and slower when compared to an observer located far away from the black hole (like us, on Earth). That means that from the point of view of this far observer, nothing happens inside a black hole u…
That's the thing that never made sense to me about the black holes. The closer you are to the event horizon, the faster the time passes for the universe around you. So reaching the event horizon should take infinite amount of the "outside time", so right before you reach the horizon, you should see the whole future of the universe, including its end, if there's any. So how do black holes gain any mass then?
[Deleted]
Re: Eldar Black Holes
#70There is a fascinating PBS Space Time video[1] about black holes that questions the very existence of whatever is "inside" a black hole. They point out that as you approach a black hole, your proper time is advancing slower and slower when compared to an observer located far away from the black hole (like us, on Earth). That means that from the point of view of this far observer, nothing happens inside a black hole u…
off-topic a bit: does anyone have suggestions for paths for the layperson toward being able to reason and intuit about this stuff at one level beyond pop physics claptrap? I have heard "the theoretical minimum" suggested in the past, but I haven't heard from anyone who has actually used it to go from zero to say, general relativity, only people who think it sounds good. It also seems like a steep investment -- I just…
I've not read this yet, but have paged though it a bit at a bookstore, and it looks like it has potential: "The Road to Reality: A Complete Guide to the Laws of the Universe" by Roger Penrose [1].
[1] https://www.amazon.com/Road-Reality-Complete-Guide-Universe/...