I've always liked the term, "Super Massive Black Hole"
It's got a nice rhythm to it
How big is a black hole, anyways? I know they're super, super dense, but they've collapsed into a tiny singularity right? So does that mean their actual physical size is super small? (compared to their previous size as a star, I mean) If it's possible to even assign something like "size" to a black hole since they affect everything around them so strongly. Maybe their "size" then is just considered the area in which they effect space around them? Or the radius of their event horizon? I don't know shit about fuck and I'm just rambling, don't mind me
Well "super massive" necessarily implies lots of mass, not necessarily any kind of physical size. However, i think using the event horizon is a fair way to describe its length or whatever, since no information can leave that boundary, it is all part of the black hole at that point.
When they first form, the event horizon will be smaller the radius of the star that collapsed to form it, but the event horizon grows as more mass gets added and the gravity increases. Super massive black holes have eaten enough mass to have whole galaxies stay in orbit around them so they're probably pretty big in the event horizon. Space inside the event horizon does weird shit so I'm not sure if the singularity is still a point in space or something weirder.
I've always liked the term, "Super Massive Black Hole"
It's got a nice rhythm to it
How big is a black hole, anyways? I know they're super, super dense, but they've collapsed into a tiny singularity right? So does that mean their actual physical size is super small? (compared to their previous size as a star, I mean) If it's possible to even assign something like "size" to a black hole since they affect everything around them so strongly. Maybe their "size" then is just considered the area in which they effect space around them? Or the radius of their event horizon? I don't know shit about fuck and I'm just rambling, don't mind me
Googling around a bit, and assuming that a black hole's "size" is its event horizon, it looks like the smallest known black hole is in GRO J1655-40 and has a radius of about ten miles. Its mass is 5.4 times the Sun, by the way.
Intermediate-mass black holes, meanwhile, are kind of hard to spot. One example this astronomy.com article I'm reading gives weights in at 50,000 suns and is 0.2 suns in radius (twice the radius of Jupiter).
Going for a supermassive black hole, meanwhile, Sagittarius A* is in the center of the Milky Way, weighs in at 4 million suns, and has a radius 17x the sun (or comfortably within Mercury's orbit). The biggest one we've found yet is in the center of Holm 15A, clocking it at 40 billion suns and a diameter that's... well, it's the size of the solar system.
Iirc, super massive is a bit more literal. They do probably have math for radius of the event horizon, but I'm pretty sure they just calculate the mass based on the gravitational effect.
Lol "just" lmao "they just do this really advanced calculation nbd"
I've always liked the term, "Super Massive Black Hole"
It's got a nice rhythm to it
How big is a black hole, anyways? I know they're super, super dense, but they've collapsed into a tiny singularity right? So does that mean their actual physical size is super small? (compared to their previous size as a star, I mean) If it's possible to even assign something like "size" to a black hole since they affect everything around them so strongly. Maybe their "size" then is just considered the area in which they effect space around them? Or the radius of their event horizon? I don't know shit about fuck and I'm just rambling, don't mind me
Theoretically black holes evaporate due to Hawking radiation, and the smaller they are the faster they evaporate. So there could be some of any size (with some old, small ones having shrunk down) but once they get smallish they go quickly. Though there is a theory that once they get down to Planck length size they can't evaporate any more, and if there were a lot of these remnants left over from the early stages of the universe they could be a dark matter candidate (as they would still be affected by gravity but would pass in between essentially everything undetected).
I've always liked the term, "Super Massive Black Hole"
It's got a nice rhythm to it
How big is a black hole, anyways? I know they're super, super dense, but they've collapsed into a tiny singularity right? So does that mean their actual physical size is super small? (compared to their previous size as a star, I mean) If it's possible to even assign something like "size" to a black hole since they affect everything around them so strongly. Maybe their "size" then is just considered the area in which they effect space around them? Or the radius of their event horizon? I don't know shit about fuck and I'm just rambling, don't mind me
Theoretically black holes evaporate due to Hawking radiation, and the smaller they are the faster they evaporate. So there could be some of any size (with some old, small ones having shrunk down) but once they get smallish they go quickly. Though there is a theory that once they get down to Planck length size they can't evaporate any more, and if there were a lot of these remnants left over from the early stages of the universe they could be a dark matter candidate (as they would still be affected by gravity but would pass in between essentially everything undetected).
No currently known black holes are losing mass due to hawking radiation. The "temperature" of the CMB throughout the universe is 2.7 kelvin. So any black hole radiating energy more slowly then that will be gaining mass due just due to the CMB. A quick check of Wikipedia says that is the amount of energy emitted by a black hole of mass approximately equal to the moon. So even the smallest known black hole is a very long time from being able to lose mass through hawking radiation.
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Brovid Hasselsmof[Growling historic on the fury road]Registered Userregular
How can black holes lose mass. I thought nothing ever being able to leave it was a black hole's whole thing
How can black holes lose mass. I thought nothing ever being able to leave it was a black hole's whole thing
My understanding is, particles can just spawn for no reason in a vacuum. It takes a bunch of energy, and they appear in a matter/antimatter pair (e.g. an electron and a positron). They initially move away from each other, but then because they have opposite charge they slam back together and annihilate each other. This would normally release a bunch of energy, but that energy is the same as what went into creating them, so it's a net of nothing happening and it usually happens so fast that nobody notices.
Close to a black hole, something strange can happen. The difference in gravitational pull (see also: spaghettification) means that one particle may be able to escape, but the other one gets sucked in. Somehow the one getting sucked in counts as negative energy? And the escaping one is the radiation?
Ok so my understanding isn't complete. Black holes are weird.
Hawking radiation is virtual particles pairs appearing out of quantum foam right outside the Black Hole. One particle falls in, the other one then has to become real and escape. The black hole lost a tiny amount of mass.
This effect is very widely accepted but very hard to actually test for.
This is a story close to the truth, it gets more complicated.
This gets you on the journey:
The thing I don't quite get is when the virtual particles form outside the black hole, and one of them falls in, why does this count as the black hole losing mass when it gains that particle?
Both of the particles have positive energy, and that energy is 'taken' form the foam, the space surrounding the particles.
This happens all the time everywhere, but normally they annihilate each other and give it back in pico seconds.
When one of them doesn't the black hole has to pay up.
I've always liked the term, "Super Massive Black Hole"
It's got a nice rhythm to it
How big is a black hole, anyways? I know they're super, super dense, but they've collapsed into a tiny singularity right? So does that mean their actual physical size is super small? (compared to their previous size as a star, I mean) If it's possible to even assign something like "size" to a black hole since they affect everything around them so strongly. Maybe their "size" then is just considered the area in which they effect space around them? Or the radius of their event horizon? I don't know shit about fuck and I'm just rambling, don't mind me
Theoretically black holes evaporate due to Hawking radiation, and the smaller they are the faster they evaporate. So there could be some of any size (with some old, small ones having shrunk down) but once they get smallish they go quickly. Though there is a theory that once they get down to Planck length size they can't evaporate any more, and if there were a lot of these remnants left over from the early stages of the universe they could be a dark matter candidate (as they would still be affected by gravity but would pass in between essentially everything undetected).
No currently known black holes are losing mass due to hawking radiation. The "temperature" of the CMB throughout the universe is 2.7 kelvin. So any black hole radiating energy more slowly then that will be gaining mass due just due to the CMB. A quick check of Wikipedia says that is the amount of energy emitted by a black hole of mass approximately equal to the moon. So even the smallest known black hole is a very long time from being able to lose mass through hawking radiation.
No black hole formed by the collapse of a star has evaporated yet, yes. However, during the early expansion phase of the universe, it's considered possible that black holes may have been formed just from pockets of high density gas and such. Possibly a very large number of them.
I've always liked the term, "Super Massive Black Hole"
It's got a nice rhythm to it
How big is a black hole, anyways? I know they're super, super dense, but they've collapsed into a tiny singularity right? So does that mean their actual physical size is super small? (compared to their previous size as a star, I mean) If it's possible to even assign something like "size" to a black hole since they affect everything around them so strongly. Maybe their "size" then is just considered the area in which they effect space around them? Or the radius of their event horizon? I don't know shit about fuck and I'm just rambling, don't mind me
Theoretically black holes evaporate due to Hawking radiation, and the smaller they are the faster they evaporate. So there could be some of any size (with some old, small ones having shrunk down) but once they get smallish they go quickly. Though there is a theory that once they get down to Planck length size they can't evaporate any more, and if there were a lot of these remnants left over from the early stages of the universe they could be a dark matter candidate (as they would still be affected by gravity but would pass in between essentially everything undetected).
No currently known black holes are losing mass due to hawking radiation. The "temperature" of the CMB throughout the universe is 2.7 kelvin. So any black hole radiating energy more slowly then that will be gaining mass due just due to the CMB. A quick check of Wikipedia says that is the amount of energy emitted by a black hole of mass approximately equal to the moon. So even the smallest known black hole is a very long time from being able to lose mass through hawking radiation.
No black hole formed by the collapse of a star has evaporated yet, yes. However, during the early expansion phase of the universe, it's considered possible that black holes may have been formed just from pockets of high density gas and such. Possibly a very large number of them.
Glancing at Wikipedia, I guess the estimated time for a 1 solar mass black hole to evaporate is 1.16×10^67 years. (The universe is 13.787×10^9 years old, for reference. We're a long way off.)
The extremely tiny black holes that could theoretically have been created by the Large Hadron Collider would have evaporated basically instantly, though.
The thing I don't quite get is when the virtual particles form outside the black hole, and one of them falls in, why does this count as the black hole losing mass when it gains that particle?
It doesn't. The analogy Hawking used of a virtual particle pair being split by the event horizon and a "negative energy particle" falling in is incorrect and Hawking even noted in his 1975 paper that it was not be taken literally as the explanation. The math is of course a lot more complicated.
The zero point energy of the universe is the same measured value everywhere, but due to relativity there is a discrepancy in mapping that energy in the deeply curved spacetime around black holes to flat spacetime at infinity. That is, the values don't agree. That discrepancy can be solved by the gravitational field energy appearing to produce photons, or the thermal energy Hawking calculated a black hole should produce. But in producing a photon, the gravitational field strength is reduced a corresponding amount of energy. Hence the black hole "shrinks" by emitting energy but there is no violation of conservation of energy like what is implied by the virtual pair analogy.
That said, the actual physical explanation of how this process happens requires a theory of quantum gravity which we don't have (yet).
SiliconStew on
Just remember that half the people you meet are below average intelligence.
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Brovid Hasselsmof[Growling historic on the fury road]Registered Userregular
I read all those posts and didn't understand any of it. I should learn not to ask questions about these things.
Not understanding is one of the best and most fun parts on quantum mechanics and cosmology. Second only to the bits and pieces where we do get a bit of understanding.
Black holes are basically magic. Especially once you start getting into ideas of what happens inside them regarding space and time going utterly bonkers. And then you start finding out how colossal they can be and suddenly there's talk of theoretical white holes that do the opposite of black holes in that they expel matter but nothing can enter them.
The more I learn about black holes the less I understand.
I like the idea that there isn't an inside, the membrane of the event horizon is essentially all one point in space, so every point on the surface of the event horizon is the same point
Black holes are basically magic. Especially once you start getting into ideas of what happens inside them regarding space and time going utterly bonkers. And then you start finding out how colossal they can be and suddenly there's talk of theoretical white holes that do the opposite of black holes in that they expel matter but nothing can enter them.
The more I learn about black holes the less I understand.
<insert something juvenile and clever about entering a white hole>
I read all those posts and didn't understand any of it. I should learn not to ask questions about these things.
Basically nothing comes out of the Black Hole i.e nothing is flying around inside and leaves across its edge (or event horizon as it is called), but if you apply quantum mechanics to black holes you get photons appearing around them and the black hole "pays" for it in the form of loosing some energy I.e getting a teensy bit smaller
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FencingsaxIt is difficult to get a man to understand, when his salary depends upon his not understandingGNU Terry PratchettRegistered Userregular
Black holes are basically magic. Especially once you start getting into ideas of what happens inside them regarding space and time going utterly bonkers. And then you start finding out how colossal they can be and suddenly there's talk of theoretical white holes that do the opposite of black holes in that they expel matter but nothing can enter them.
The more I learn about black holes the less I understand.
<insert something juvenile and clever about entering a white hole>
So what is it?
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JedocIn the scupperswith the staggers and jagsRegistered Userregular
Too late, the joke collapsed under its own weight: <.>
Now no information about it can escape to the rest of the internet.
I have learned from the chat (never read the comments) that Jack Black's mom --Judith Love Cohen-- worked for NASA. She was an aerospace engineer, and among her important projects, "helped create the Abort-Guidance System which rescued the Apollo 13 astronauts." HOLD THE FUVK ON this is just
"[She] went into labor with her fourth child on August 28, 1969. On her way to the hospital, Cohen decided to stop at the office to pick up a computer printout of the problem she had been working on. Later that day, she had called her boss to let him know she had solved the problem, and in the meantime, had had a healthy baby."
She was also, like, a ballerina, and retired to found a publishing company author a bunch of books...
I have learned from the chat (never read the comments) that Jack Black's mom --Judith Love Cohen-- worked for NASA. She was an aerospace engineer, and among her important projects, "helped create the Abort-Guidance System which rescued the Apollo 13 astronauts." HOLD THE FUVK ON this is just
"[She] went into labor with her fourth child on August 28, 1969. On her way to the hospital, Cohen decided to stop at the office to pick up a computer printout of the problem she had been working on. Later that day, she had called her boss to let him know she had solved the problem, and in the meantime, had had a healthy baby."
She was also, like, a ballerina, and retired to found a publishing company author a bunch of books...
I feel like this actually does kind of explain the existence of Jack Black, sure.
I have learned from the chat (never read the comments) that Jack Black's mom --Judith Love Cohen-- worked for NASA. She was an aerospace engineer, and among her important projects, "helped create the Abort-Guidance System which rescued the Apollo 13 astronauts." HOLD THE FUVK ON this is just
"[She] went into labor with her fourth child on August 28, 1969. On her way to the hospital, Cohen decided to stop at the office to pick up a computer printout of the problem she had been working on. Later that day, she had called her boss to let him know she had solved the problem, and in the meantime, had had a healthy baby."
She was also, like, a ballerina, and retired to found a publishing company author a bunch of books...
Also, to be specific, that baby was Jack Black.
One of his older brothers is Neil Siegel, who worked in the US Army making UAV programs (yikes) but also has a notable civilian resume because of that:
Siegel has had a major impact on the design and capabilities of many types of mobile consumer electronics, including smart phones, GPS receivers, and so forth. He is the documented earliest creator of a complete, operating adaptation of the internet to wireless operation, and many important / related technologies that are widely used today in such wireless devices, including:
GPS-enabled mobile devices[16]
Automatic orientation of a map display to match the geographic cardinal points[17]
Optimizing unicast protocols (including TCP) for use on low-bandwidth, wireless networks[18]
Performing many security administrative and control tasks remotely[19]
Managing and administering a large network of wireless devices[20]
Increasing battery life on GPS-enabled devices[21]
Pretty interesting family, all told.
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3cl1ps3I will build a labyrinth to house the cheeseRegistered Userregular
Hidden in the neck of this “hourglass” of light are the very beginnings of a new star — a protostar. The clouds of dust and gas within this region are only visible in infrared light, the wavelengths that Webb specializes in: go.nasa.gov/3TKluzI
Posts
It's got a nice rhythm to it
How big is a black hole, anyways? I know they're super, super dense, but they've collapsed into a tiny singularity right? So does that mean their actual physical size is super small? (compared to their previous size as a star, I mean) If it's possible to even assign something like "size" to a black hole since they affect everything around them so strongly. Maybe their "size" then is just considered the area in which they effect space around them? Or the radius of their event horizon? I don't know shit about fuck and I'm just rambling, don't mind me
Googling around a bit, and assuming that a black hole's "size" is its event horizon, it looks like the smallest known black hole is in GRO J1655-40 and has a radius of about ten miles. Its mass is 5.4 times the Sun, by the way.
Intermediate-mass black holes, meanwhile, are kind of hard to spot. One example this astronomy.com article I'm reading gives weights in at 50,000 suns and is 0.2 suns in radius (twice the radius of Jupiter).
Going for a supermassive black hole, meanwhile, Sagittarius A* is in the center of the Milky Way, weighs in at 4 million suns, and has a radius 17x the sun (or comfortably within Mercury's orbit). The biggest one we've found yet is in the center of Holm 15A, clocking it at 40 billion suns and a diameter that's... well, it's the size of the solar system.
Lol "just" lmao "they just do this really advanced calculation nbd"
Theoretically black holes evaporate due to Hawking radiation, and the smaller they are the faster they evaporate. So there could be some of any size (with some old, small ones having shrunk down) but once they get smallish they go quickly. Though there is a theory that once they get down to Planck length size they can't evaporate any more, and if there were a lot of these remnants left over from the early stages of the universe they could be a dark matter candidate (as they would still be affected by gravity but would pass in between essentially everything undetected).
No currently known black holes are losing mass due to hawking radiation. The "temperature" of the CMB throughout the universe is 2.7 kelvin. So any black hole radiating energy more slowly then that will be gaining mass due just due to the CMB. A quick check of Wikipedia says that is the amount of energy emitted by a black hole of mass approximately equal to the moon. So even the smallest known black hole is a very long time from being able to lose mass through hawking radiation.
My understanding is, particles can just spawn for no reason in a vacuum. It takes a bunch of energy, and they appear in a matter/antimatter pair (e.g. an electron and a positron). They initially move away from each other, but then because they have opposite charge they slam back together and annihilate each other. This would normally release a bunch of energy, but that energy is the same as what went into creating them, so it's a net of nothing happening and it usually happens so fast that nobody notices.
Close to a black hole, something strange can happen. The difference in gravitational pull (see also: spaghettification) means that one particle may be able to escape, but the other one gets sucked in. Somehow the one getting sucked in counts as negative energy? And the escaping one is the radiation?
Ok so my understanding isn't complete. Black holes are weird.
This effect is very widely accepted but very hard to actually test for.
This is a story close to the truth, it gets more complicated.
This gets you on the journey:
This happens all the time everywhere, but normally they annihilate each other and give it back in pico seconds.
When one of them doesn't the black hole has to pay up.
No black hole formed by the collapse of a star has evaporated yet, yes. However, during the early expansion phase of the universe, it's considered possible that black holes may have been formed just from pockets of high density gas and such. Possibly a very large number of them.
Glancing at Wikipedia, I guess the estimated time for a 1 solar mass black hole to evaporate is 1.16×10^67 years. (The universe is 13.787×10^9 years old, for reference. We're a long way off.)
The extremely tiny black holes that could theoretically have been created by the Large Hadron Collider would have evaporated basically instantly, though.
It doesn't. The analogy Hawking used of a virtual particle pair being split by the event horizon and a "negative energy particle" falling in is incorrect and Hawking even noted in his 1975 paper that it was not be taken literally as the explanation. The math is of course a lot more complicated.
The zero point energy of the universe is the same measured value everywhere, but due to relativity there is a discrepancy in mapping that energy in the deeply curved spacetime around black holes to flat spacetime at infinity. That is, the values don't agree. That discrepancy can be solved by the gravitational field energy appearing to produce photons, or the thermal energy Hawking calculated a black hole should produce. But in producing a photon, the gravitational field strength is reduced a corresponding amount of energy. Hence the black hole "shrinks" by emitting energy but there is no violation of conservation of energy like what is implied by the virtual pair analogy.
That said, the actual physical explanation of how this process happens requires a theory of quantum gravity which we don't have (yet).
The more I learn about black holes the less I understand.
<insert something juvenile and clever about entering a white hole>
Basically nothing comes out of the Black Hole i.e nothing is flying around inside and leaves across its edge (or event horizon as it is called), but if you apply quantum mechanics to black holes you get photons appearing around them and the black hole "pays" for it in the form of loosing some energy I.e getting a teensy bit smaller
So what is it?
Now no information about it can escape to the rest of the internet.
~ Buckaroo Banzai
Looks like we’ve hit 710k now
"[She] went into labor with her fourth child on August 28, 1969. On her way to the hospital, Cohen decided to stop at the office to pick up a computer printout of the problem she had been working on. Later that day, she had called her boss to let him know she had solved the problem, and in the meantime, had had a healthy baby."
She was also, like, a ballerina, and retired to found a publishing company author a bunch of books...
I feel like this actually does kind of explain the existence of Jack Black, sure.
One of his older brothers is Neil Siegel, who worked in the US Army making UAV programs (yikes) but also has a notable civilian resume because of that: Pretty interesting family, all told.