scoffs Well yeah everyone and their aunt knows singularities have 5 dimensions.
Black hole singularity is a surface not a point
71–80 of 239 posts
Re: Black hole singularity is a surface not a point
#72Earlier quoted context omitted.
As someone with basically only popsci knowledge of black holes: people claiming it would be a literal point never made much sense - fundamentally, common sense (as much as it can apply here) dictates that you cannot compress particles to an absolute point.
Aren't fundamental particles like electrons and quarks treated as points?
Kind of, but not really.. though there are simple models with electrons as a point charge, a more accurate model involves the electron field describing the probability of an electron existing at any region in space (not to be confused with the electromagnetic field, the medium in which photons propagate).
Re: Black hole singularity is a surface not a point
#73Should be pointed out that this is a critique of common popsci journalism tropes and not a fancy new research result. Anyone who has taken a graduate level class in General Relativity would have been able to tell you the same.
As someone with basically only popsci knowledge of black holes: people claiming it would be a literal point never made much sense - fundamentally, common sense (as much as it can apply here) dictates that you cannot compress particles to an absolute point.
The question of "what holds it up?" is where that leads to. There's an interesting history of answering that question again and again - and the discovery of new types of stars each time.
History of the Universe : What Is Hidden In The Core Of A Neutron Star? - https://youtu.be/YoYjkNQ27T8
That video goes into it... without getting mathy at any point.
One of the bits that you're having trouble with is the compression of matter to a point. There's a theoretical type of black hole known as a kugelblitz - https://en.wikipedia.org/wiki/Kugelblitz_(astrophysics)
A kugelblitz is a theoretical astrophysical object predicted by general relativity. It is a concentration of heat, light, or radiation so intense that its energy forms an event horizon and becomes self-trapped. In other words, if enough radiation is aimed into a region of space, the concentration of energy can warp spacetime so much that it creates a black hole. This would be a black hole the original mass–energy of which was in the form of radiant energy rather than matter
Re: Black hole singularity is a surface not a point
#74Earlier quoted context omitted.
"A really interesting and cool thing for astronomers to talk about...but you might want to pray that not one of 'em ever comes within a million trillion miles of the Earth."
Unfortunately, there is a rather large one not one sixth of that distance away (a million trillion miles is actually rather large - 170 kly - approximately double the size of our galaxy)
Yes - I took the grandparent comment's "descr to a non-physicist" as "describe to someone who really isn't into math or hard sciences". Those folks will hear "million trillion" as "a really Really REALLY REALLY big number". Not as "1 x 10^18".
Re: Black hole singularity is a surface not a point
#75what's really going to blow your mind is while you probably assumed or knew spinning black holes move space around them spinning black holes also move TIME around them * https://www.science.org/doi/10.1126/sciadv.ady9068 so in theory a spinning black hole that's been around for billions of years has a time drag around it in a path that is billions of years old (no we can't navigate it because yes that would be time t…
> densest objects before black holes
Not quite, I think a (theoretical) quark star would be higher density?
Re: Black hole singularity is a surface not a point
#76Re: Black hole singularity is a surface not a point
#77Should be pointed out that this is a critique of common popsci journalism tropes and not a fancy new research result. Anyone who has taken a graduate level class in General Relativity would have been able to tell you the same.
As someone with basically only popsci knowledge of black holes: people claiming it would be a literal point never made much sense - fundamentally, common sense (as much as it can apply here) dictates that you cannot compress particles to an absolute point.
Common sense cannot be trusted on matters like these. Common sense is calibrated for reasoning over matters encountered in daily life. The further away we get from that, into more and more exotic phenomena, the less common sense can apply. Black holes are very far from the domain of common sense.
Re: Black hole singularity is a surface not a point
#78Should be pointed out that this is a critique of common popsci journalism tropes and not a fancy new research result. Anyone who has taken a graduate level class in General Relativity would have been able to tell you the same.
As someone with basically only popsci knowledge of black holes: people claiming it would be a literal point never made much sense - fundamentally, common sense (as much as it can apply here) dictates that you cannot compress particles to an absolute point.
Common sense - the experience gained from your common everyday experience of reality - does not apply in black holes.
Common sense would tell you they can't exist at all because you can't compress atoms - you have lived your entire life with atoms being entirely incompressible for the practical purpose of anything you do.
Leaning on common sense to discuss fundamental physics has been wrong since round about the start of the practice of physics.
Re: Black hole singularity is a surface not a point
#79Re: Black hole singularity is a surface not a point
#80Well... yeah? That's describing the event horizon. It's a term roughly as widely used as "singularity". Talking about the inside of a black hole is indeed rather pop-misunderstood though, yes. But it's not like physicists are especially confident about the details either. Theoretical astrophysics changes a lot as time goes on and our instruments improve, and it's a rather hard field to do experiments on to get better…
No, sorry, the singular surface in a Schwarzschild spacetime is not the event horizon. Nothing particularly interesting (from the GR point of view) happens at the event horizon.