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To add to the conversation, I would imagine the temperature inside a black hole to be immense considering the amount of matter and gravity compressing it all together, similar to stars and how they compress various elements into a white-hot mass.
Assuming anything could survive the tidal forces, living organisms would also have to contend with temperatures many orders of magnitude greater than stars.
This is where it would get strange. The heat would be coming from the accretion disk around the outside of the event horizon, not the singularity itself. The immense gravity of the singularity would prevent IR radiation from radiating outward. However, the material that is falling into the event horizon would be super-heated, so the further one is from the singularity the hotter it would be.
I would further add that there are no stable circular orbits in the event horizon, particularly for an object the size of a planet like Earth. The paper posted in the OP is based upon the orbit of a single photon, and it was anything but circular.
To the contrary, the temp is reverse proportional to the size of the hole. Bigger holes - colder. All the way down to -273C = 0K.
Hmmm, I didn't even know any research had been done in this field but I looked around and saw Hawking radiation which seems to touch on this. Problem with that is that it seems to still be just a speculative theory right now (the LHC at CERN might be able to prove or disprove it though). Also this seems to only measure the temp at the event horizon.
Fact of the matter is that we might not ever know for sure what the temp inside a supermassive black hole is. We cant exactly go in with a thermometer. Conventional wisdom would say that it's hot due to the immense gravitational compression squeezing everything that didnt make it out of the event horizon but seeing as how conventional laws of space-time don't really apply inside, I could be (and probably am) way off!
Hmmm, I didn't even know any research had been done in this field but I looked around and saw Hawking radiation which seems to touch on this....
We cant exactly go in with a thermometer.
You know what, my apologies. I checked my sources, and it is about perceived thermodynamic temperature of the event horizon as it appears to external (outside of the BH) observer. Not about the temp inside the BH.
It's not the point of whether we can go there with a thermometer though, we use spectral data to read the temp of the photosphere of the stars and we use math models to estimate the temp in the core. The point is that we don't have any technology or even any theoretical idea about receiving any info from inside of the black hole. All we got is electromagnetic based, i.e. photons but phonots by definition circle the BH by elliptic orbits and don't go beyond the EH.
Now, inside the black hole. How about we estimate what kind of densities we may deal with inside the BH.
The Schwarzschild radius: R= 2*G*m/(c^2) where G is graviconstant (6.67E-11 SI), c is the speed of light in vacuum (299792458 SI), and m is the mass of the object.
Suppose we pack the object into a sphere, the volume V should be 4* π * (R^3)/3 then. And, since the density ρ = m/V, let's resolve those equations to see what kind of mass we should have to reach the density of water, 1000 SI, i.e. 1 g/ccm. Check my math, I got the BH mass 2.59E+38 kg, i.e. 130,000,000 sun masses (assuming Sun's mass of 1.99E+30 kg). Which is about 1/10000 of the mass of the Milky Way and the definition of supermassive BH calls for 1e12 solar masses. So it's not even a super one, it's your average next door BH. Now, the R I got is 3.84E+11 which is about 2.58 AU, between Mars and Jupiter, closer to Mars. So if we pack a medium size black hole into about Mars orbit size plus a tad more, we got average density of 1 g/ccm, the density of the medium in which our fishes and whales spend most (if not all) of their lives.
Hence, most of the black holes may have average density of water. Whether it's uniform or not, can't tell right off the top without doing major math acrobatics, but there should be layers of this exact density and less. Even the density of air we breathe, no problem. As the BH gets heavier, then the density falls very fast, to essentially vacuum, you can build a chart in Excel with these formulas.
So, density won't be a problem per se. Temperatures, dunno. That mass must be something but what it exactly ends up to be - can't tell. Violence of the BH birth can settle like it did for our Solar system and below the EH, that's life as usual, normal laws of physics apply and the life inside the BH may be just the same as outside. We may be living inside one SOB of a BH. What else can threaten life as we know it - gravity gradients? Even if they are strong enough to rip my pelvis off my spine, live organisms could assume shape that can cope with this, flat and wide, or equalize vertically.
You know what, my apologies. I checked my sources, and it is about perceived thermodynamic temperature of the event horizon as it appears to external (outside of the BH) observer. Not about the temp inside the BH.
It's not the point of whether we can go there with a thermometer though, we use spectral data to read the temp of the photosphere of the stars and we use math models to estimate the temp in the core. The point is that we don't have any technology or even any theoretical idea about receiving any info from inside of the black hole. All we got is electromagnetic based, i.e. photons but phonots by definition circle the BH by elliptic orbits and don't go beyond the EH.
Now, inside the black hole. How about we estimate what kind of densities we may deal with inside the BH.
The Schwarzschild radius: R= 2*G*m/(c^2) where G is graviconstant (6.67E-11 SI), c is the speed of light in vacuum (299792458 SI), and m is the mass of the object.
Suppose we pack the object into a sphere, the volume V should be 4* π * (R^3)/3 then. And, since the density ρ = m/V, let's resolve those equations to see what kind of mass we should have to reach the density of water, 1000 SI, i.e. 1 g/ccm. Check my math, I got the BH mass 2.59E+38 kg, i.e. 130,000,000 sun masses (assuming Sun's mass of 1.99E+30 kg). Which is about 1/10000 of the mass of the Milky Way and the definition of supermassive BH calls for 1e12 solar masses. So it's not even a super one, it's your average next door BH. Now, the R I got is 3.84E+11 which is about 2.58 AU, between Mars and Jupiter, closer to Mars. So if we pack a medium size black hole into about Mars orbit size plus a tad more, we got average density of 1 g/ccm, the density of the medium in which our fishes and whales spend most (if not all) of their lives.
Hence, most of the black holes may have average density of water. Whether it's uniform or not, can't tell right off the top without doing major math acrobatics, but there should be layers of this exact density and less. Even the density of air we breathe, no problem. As the BH gets heavier, then the density falls very fast, to essentially vacuum, you can build a chart in Excel with these formulas.
So, density won't be a problem per se. Temperatures, dunno. That mass must be something but what it exactly ends up to be - can't tell. Violence of the BH birth can settle like it did for our Solar system and below the EH, that's life as usual, normal laws of physics apply and the life inside the BH may be just the same as outside. We may be living inside one SOB of a BH. What else can threaten life as we know it - gravity gradients? Even if they are strong enough to rip my pelvis off my spine, live organisms could assume shape that can cope with this, flat and wide, or equalize vertically.
That's my USD $0.02 worth.
The temperature at the inner layer of the Event Horizon is dependent upon on the chemical composition of the gas layer that has been accreted. At very high temperatures, as in the environment of a black hole, high energy photon interactions with nuclei or even with other photons, can create an electron-positron plasma. All the energy released by accretion does not have to appear as outgoing luminosity (as in x-ray or gamma-ray bursts), since energy can be lost through the Event Horizon. Which would make it difficult, if not impossible, to know the temperature at the inner layer of the Event Horizon. At the very least the temperature could be potentially higher than the measured luminosity would imply.
The temperature at the inner layer of the Event Horizon is dependent upon on the chemical composition of the gas layer that has been accreted. At very high temperatures, as in the environment of a black hole, high energy photon interactions with nuclei or even with other photons, can create an electron-positron plasma. All the energy released by accretion does not have to appear as outgoing luminosity (as in x-ray or gamma-ray bursts), since energy can be lost through the Event Horizon. Which would make it difficult, if not impossible, to know the temperature at the inner layer of the Event Horizon. At the very least the temperature could be potentially higher than the measured luminosity would imply.
Best of Wikipedia for you. See all these "weasel words" I highlighted?
Alright, with a bright accretion disk things get hot, as hot as 10e13 sols inward/outward, plenty of energy to swallow to kill any organic life inside. Fine. But not all BHs have enough food to light up any decent accretion disk. Then what? Hawkings rad, by the formula, goes all the way to 0K for large holes. Now, we got a medium size BH as I described earlier with no accretion to warm it up or just enough accretion to keep insides warm and comfy enough for life, then what? Or the BH is large enough for any accretion energy dissipate, and for a hole large enough, there will be no disk, it would swallow the whole galaxy like a peanut and a billion LYs inward, this event won't have any impact.
Now, there is also dark matter but it does not contribute to Eddington lumi, DM does not play electromagnetic anything. Here you go, look ma, a BH with life!
Best of Wikipedia for you. See all these "weasel words" I highlighted?
I do not know what you are trying to imply by "weasel words," but since we are discussing black holes specifically, and the Eddington Limit can be applied to any object, I felt it was necessary to identify black holes specifically.
Also, since nobody knows how much energy is lost to the black hole, it would not be accurate to state what the temperature may be precisely. The Eddington Limit merely tells us what the temperature must be, at a minimum, based upon the luminosity. That does not mean that the temperatures could not be higher.
Quote:
Originally Posted by geekie
Alright, with a bright accretion disk things get hot, as hot as 10e13 sols inward/outward, plenty of energy to swallow to kill any organic life inside. Fine. But not all BHs have enough food to light up any decent accretion disk. Then what? Hawkings rad, by the formula, goes all the way to 0K for large holes. Now, we got a medium size BH as I described earlier with no accretion to warm it up or just enough accretion to keep insides warm and comfy enough for life, then what? Or the BH is large enough for any accretion energy dissipate, and for a hole large enough, there will be no disk, it would swallow the whole galaxy like a peanut and a billion LYs inward, this event won't have any impact.
Now, there is also dark matter but it does not contribute to Eddington lumi, DM does not play electromagnetic anything. Here you go, look ma, a BH with life!
In the case where the black hole has no accretion disk, and ignoring the effects of tidal forces inside the Event Horizon, how could there be life? Life requires some form of energy, and it certainly is not going to get that from the singularity, regardless of its mass.
The Eddington Limit merely tells us what the temperature must be, at a minimum, based upon the luminosity. That does not mean that the temperatures could not be higher.
Again, you reduce accretion energy - you got no problems with this energy killing life. Problem solved.
Quote:
Originally Posted by Glitch
In the case where the black hole has no accretion disk, and ignoring the effects of tidal forces inside the Event Horizon, how could there be life? Life requires some form of energy, and it certainly is not going to get that from the singularity, regardless of its mass.
Again, try to understand the formulae I posted earlier and the numbers crunched using those:
you can make a black hole from nearly a vacuum
in which case tidal forces will be negligible
As of "singularity", Hawkins et al painted themselves into a corner with it, it's nothing but mathematical deficiency of the model. Quantum gravity took care of it - there is no singularity, no infinite density. You put sufficient mass of whatever into a volume that fits inside that S-radius (see the numbers I presented earlier) - you got a black hole. But inside there can be stars and galaxies and clusters of galaxies, the honycomb of the dark matter etc etc. Business as usual. Life included. We may be living inside a BH for that matter. Energy? Why this should be a problem? There may be enough remaining entropy since formation of a huge BH to sustain life for billions of years not to mention that a BH can always go feed for more.
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