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Most images of black holes are illustrations. Here’s what our telescopes capture

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Re: Most images of black holes are illustrations. Here’s what our telescopes capture

#41

Post by qubex »

blackrock wrote: post #38
oevi wrote: post #24

Black holes are an excellent example for so called "cognitive metaphors". Because we found no better analogy, we named them "holes" despite the fact that they are basically the opposite: an object with enormous mass. This influences our thinking and our language when we discuss problems concerning black holes. We talk about "inside the black hole", "light cannot escape the black hole" or "spitting things out of the b…

I would prefer if black holes were called "Dark Stars". Because that really is what they are. A weird star that is so massive, its gravitational field distorted the fabric of its local space, that not even light can escape it. It is theoretically possible that the black hole is still performing fusion, and emitting light and heat, like a regular star. But its gravitational field is so intense, that even light cannot…

The term “Dark Star” actually predates the term “Black Hole” by a very long margin (first recorded usage 1783) [0] for classical Newtonian objects whose mass is so large that the escape velocity at their surface exceeds the finite speed of light. Black Holes are very different beasts (self-sustaining concentrations of space-time curvature), despite their popular explanation as being “objects so massive space cannot escape”.

It’s extremely improbable that any “classical” (non exotic-quantum) processes are going on within the horizon because it’s very clear that the strength of the gravitational field would far exceed the hydrostatic pressure generated by fusion reactions. It far exceeds the degeneracy forces that prevent neutron stars from collapsing further under their own mass.

[0] https://en.wikipedia.org/wiki/Dark_star_(Newtonian_mechanics...

Re: Most images of black holes are illustrations. Here’s what our telescopes capture

#42

Post by Moodles »

blackrock wrote: post #38
oevi wrote: post #24

Black holes are an excellent example for so called "cognitive metaphors". Because we found no better analogy, we named them "holes" despite the fact that they are basically the opposite: an object with enormous mass. This influences our thinking and our language when we discuss problems concerning black holes. We talk about "inside the black hole", "light cannot escape the black hole" or "spitting things out of the b…

I would prefer if black holes were called "Dark Stars". Because that really is what they are. A weird star that is so massive, its gravitational field distorted the fabric of its local space, that not even light can escape it. It is theoretically possible that the black hole is still performing fusion, and emitting light and heat, like a regular star. But its gravitational field is so intense, that even light cannot…

I believe the term "frozen star" was also used for a time to describe black holes. I'm no physicist but I'm not sure this is an appropriate term either: blackholes are supposed to be really cold inside but really hot from the outside.

Re: Most images of black holes are illustrations. Here’s what our telescopes capture

#43

Post by dalbasal »

westoncb wrote: post #29
oevi wrote: post #24

Black holes are an excellent example for so called "cognitive metaphors". Because we found no better analogy, we named them "holes" despite the fact that they are basically the opposite: an object with enormous mass. This influences our thinking and our language when we discuss problems concerning black holes. We talk about "inside the black hole", "light cannot escape the black hole" or "spitting things out of the b…

I think this is something that deserves much greater general awareness. I think by default we're pretty unaware of the kind of analogizing/metaphoring that takes place when we conceptualize anything—but it's completely pervasive. I see it as a kind of subtle 'dust on the lens' of the microscope which we use to observe things generally. It's an (in a certain sense) inescapable artifact due to the fact the we conceptua…

One that I think comes up often is the robots/automation metaphor. Technology has reduced 90% or more of farm labour needs, multiplied industrial output many times, etc. We've seen a lot of automation, but it's been vague economics.

When we think back on these things, we see technology, tools, & machines like tractors and looms. When we look forward we see robots and automation.

Practically this has 2 effects. First, we come back with a Jetsons lime picture, everything is the same as a regular hotel but the maid is a robot, the front desk is an ATM, the barman is a robot arm and the resteraunt is a Japanese conveyor belt. Robots are human shaped metaphors for technology, placeholders for unknowns.

Second, we think in terms of replacement. In reality, it's really more like efficiency. A tractor still uses a farmer, but requires a lot less time and effort to get a field ploughed. Again, there's a difference in how we think when looking back or forward.

Re: Most images of black holes are illustrations. Here’s what our telescopes capture

#44

Post by akvadrako »

blackrock wrote: post #38
oevi wrote: post #24

Black holes are an excellent example for so called "cognitive metaphors". Because we found no better analogy, we named them "holes" despite the fact that they are basically the opposite: an object with enormous mass. This influences our thinking and our language when we discuss problems concerning black holes. We talk about "inside the black hole", "light cannot escape the black hole" or "spitting things out of the b…

I would prefer if black holes were called "Dark Stars". Because that really is what they are. A weird star that is so massive, its gravitational field distorted the fabric of its local space, that not even light can escape it. It is theoretically possible that the black hole is still performing fusion, and emitting light and heat, like a regular star. But its gravitational field is so intense, that even light cannot…

> It is theoretically possible that the black hole is still performing fusion, and emitting light and heat, like a regular star.

I don't think that's a useful picture. It's closer to the truth to say that from the outside perspective, all the information and energy sits on the border and there is not even an inside to speak about. In other words, it's the edge of the universe and what's past the event horizon is another universe. Not like a star at all.

Re: Most images of black holes are illustrations. Here’s what our telescopes capture

#45

Post by akvadrako »

4ad wrote: post #32
oevi wrote: post #24

Black holes are an excellent example for so called "cognitive metaphors". Because we found no better analogy, we named them "holes" despite the fact that they are basically the opposite: an object with enormous mass. This influences our thinking and our language when we discuss problems concerning black holes. We talk about "inside the black hole", "light cannot escape the black hole" or "spitting things out of the b…

No, black holes are topological holes. It's a mathematical abstraction, not merely a cognitive metaphor.

I'm pretty sure every "mathematical abstraction" is a "cognitive metaphor".

Re: Most images of black holes are illustrations. Here’s what our telescopes capture

#46

Post by sandworm101 »

Saying we have not "seen" a BH is like saying we haven't seen the core of any other star. We haven't, we cannot and never will. Such things are hidden behind the massively bright regions they power (corona, acretion disks ect). We must calculate the interior of a BH as we calculate the interior of jupiter. That doesnt make thier existance any less real or profound.

Re: Most images of black holes are illustrations. Here’s what our telescopes capture

#47

Post by RileyJames »

onion-soup wrote: post #40

It bugs me how almost never in astronomy-related animated gifs authors never tell explicitly how long is 1 frame. In that blue x-ray burst image, am I looking at 1000 years per frame, 1 second? 1 minute? Really frustrating

I found this gif particularly amazing because it did. And the others a little underwhelming.

https://cdn.vox-cdn.com/uploads/chorus_asset/file/9984865/st...

Re: Most images of black holes are illustrations. Here’s what our telescopes capture

#48

Post by Santosh83 »

Moodles wrote: post #42
blackrock wrote: post #38

Earlier quoted context omitted.

I would prefer if black holes were called "Dark Stars". Because that really is what they are. A weird star that is so massive, its gravitational field distorted the fabric of its local space, that not even light can escape it. It is theoretically possible that the black hole is still performing fusion, and emitting light and heat, like a regular star. But its gravitational field is so intense, that even light cannot…

I believe the term "frozen star" was also used for a time to describe black holes. I'm no physicist but I'm not sure this is an appropriate term either: blackholes are supposed to be really cold inside but really hot from the outside.

I think frozen star refers to the fact that from an outside observer's perspective, the star seems to stop collapsing at the last possible moment, suspended in time as it were, because light from the moment of black hole formation takes an infinite amount of time to reach the observer.

Re: Most images of black holes are illustrations. Here’s what our telescopes capture

#49

Post by Santosh83 »

blackrock wrote: post #38
oevi wrote: post #24

Black holes are an excellent example for so called "cognitive metaphors". Because we found no better analogy, we named them "holes" despite the fact that they are basically the opposite: an object with enormous mass. This influences our thinking and our language when we discuss problems concerning black holes. We talk about "inside the black hole", "light cannot escape the black hole" or "spitting things out of the b…

I would prefer if black holes were called "Dark Stars". Because that really is what they are. A weird star that is so massive, its gravitational field distorted the fabric of its local space, that not even light can escape it. It is theoretically possible that the black hole is still performing fusion, and emitting light and heat, like a regular star. But its gravitational field is so intense, that even light cannot…

Gravitational collapse overwhelms fusion pressure much before the black hole stage is reached, i.e., neutron stars. Also general relativity seems to indicate unambiguously that the in-falling matter collapses to a singularity, which obviously cannot have any kind of structure or process inside it. I guess only a quantum theory of gravity can clear up this enigma.

Re: Most images of black holes are illustrations. Here’s what our telescopes capture

#50

Post by 4ad »

blackrock wrote: post #38
oevi wrote: post #24

Black holes are an excellent example for so called "cognitive metaphors". Because we found no better analogy, we named them "holes" despite the fact that they are basically the opposite: an object with enormous mass. This influences our thinking and our language when we discuss problems concerning black holes. We talk about "inside the black hole", "light cannot escape the black hole" or "spitting things out of the b…

I would prefer if black holes were called "Dark Stars". Because that really is what they are. A weird star that is so massive, its gravitational field distorted the fabric of its local space, that not even light can escape it. It is theoretically possible that the black hole is still performing fusion, and emitting light and heat, like a regular star. But its gravitational field is so intense, that even light cannot…

> It is theoretically possible that the black hole is still performing fusion, and emitting light and heat, like a regular star. But its gravitational field is so intense, that even light cannot escape it.

No, it is not. In GR, once critical density is reached, gravitational collapse is inevitable: https://en.wikipedia.org/wiki/Penrose–Hawking_singularity_th....

It's possible this doesn't hold true in some theory of quantum gravity, but you'd get some exotic matter, not "stars still performing fusion, and emitting light and heat, like a regular star".

Please note that no fusion is happening in white dwarfs, nor in neutron stars.

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