Ok, thanks. That said, I understand there could very well still be as yet undetected (or undetectable) dark matter black holes, around which any dark matter particles could be interacting quite frequently.Chris Peterson wrote: ↑Mon Oct 21, 2024 1:37 pmExcept in actual usage, "temperature" simply isn't used that way. Absent a large enough population of particles for statistics to be meaningful, you would just consider the energy of a particle (which could be all over the place as it absorbs or emits photons and changes its energy state).johnnydeep wrote: ↑Mon Oct 21, 2024 1:21 pmBut a collection of a million atoms could have the same temperature as a collection of 100 atoms due simply to the average velocity of the atoms being the same (however impeded by collisions those atoms may be). So, it makes sense to me to say that a single atom with that same average velocity could be said to have that same temperature.Chris Peterson wrote: ↑Sun Oct 20, 2024 11:38 pm
"Temperature" is a thermodynamic property that only makes sense across a statistically meaningful population of particles. A single atom doesn't have a "temperature". It reflects the average kinetic energy of a collection of particles.
Particle collisions are extremely rare. At the particle scale, baryonic matter interacts with itself through the electromagnetic force. Not the very weak gravitational force. Very, very early in the Universe the particle density of dark matter may have been high enough that actual collisions occurred. No more.Why couldn't dark matter interact with itself via collisions? We already know dark matter can affect other dark matter via gravity.Because our ordinary usage of "temperature" involves collisions between particles and the transfer of energy, and because particles of dark matter essentially don't interact, they don't really possess a temperature as such (although they may have very high velocities, so in some settings are treated as having a sort of temperature. But it's not something we measure; rather, it's a theoretical concept).
APOD: Dark Matter in a Simulated Universe (2024 Oct 20)
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Re: APOD: Dark Matter in a Simulated Universe (2024 Oct 20)
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Re: APOD: Dark Matter in a Simulated Universe (2024 Oct 20)
I don't think the concept of a dark matter black hole makes any sense. The nature of the matter is completely lost in a black hole. It's a singularity with mass. Why would one formed from baryonic matter be any different from one formed from dark matter?johnnydeep wrote: ↑Mon Oct 21, 2024 7:19 pmOk, thanks. That said, I understand there could very well still be as yet undetected (or undetectable) dark matter black holes, around which any dark matter particles could be interacting quite frequently.Chris Peterson wrote: ↑Mon Oct 21, 2024 1:37 pmExcept in actual usage, "temperature" simply isn't used that way. Absent a large enough population of particles for statistics to be meaningful, you would just consider the energy of a particle (which could be all over the place as it absorbs or emits photons and changes its energy state).johnnydeep wrote: ↑Mon Oct 21, 2024 1:21 pm
But a collection of a million atoms could have the same temperature as a collection of 100 atoms due simply to the average velocity of the atoms being the same (however impeded by collisions those atoms may be). So, it makes sense to me to say that a single atom with that same average velocity could be said to have that same temperature.
Particle collisions are extremely rare. At the particle scale, baryonic matter interacts with itself through the electromagnetic force. Not the very weak gravitational force. Very, very early in the Universe the particle density of dark matter may have been high enough that actual collisions occurred. No more.
Why couldn't dark matter interact with itself via collisions? We already know dark matter can affect other dark matter via gravity.
Chris
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Re: APOD: Dark Matter in a Simulated Universe (2024 Oct 20)
Yes, that's true. But the black hole still might have been formed predominantly from dark matter initially, though perhaps we'd never be able to confirm that. And clearly, since dark matter perfuses all of space, black holes must be swallowing some up all the time!Chris Peterson wrote: ↑Mon Oct 21, 2024 10:18 pmI don't think the concept of a dark matter black hole makes any sense. The nature of the matter is completely lost in a black hole. It's a singularity with mass. Why would one formed from baryonic matter be any different from one formed from dark matter?johnnydeep wrote: ↑Mon Oct 21, 2024 7:19 pmOk, thanks. That said, I understand there could very well still be as yet undetected (or undetectable) dark matter black holes, around which any dark matter particles could be interacting quite frequently.Chris Peterson wrote: ↑Mon Oct 21, 2024 1:37 pm
Except in actual usage, "temperature" simply isn't used that way. Absent a large enough population of particles for statistics to be meaningful, you would just consider the energy of a particle (which could be all over the place as it absorbs or emits photons and changes its energy state).
Particle collisions are extremely rare. At the particle scale, baryonic matter interacts with itself through the electromagnetic force. Not the very weak gravitational force. Very, very early in the Universe the particle density of dark matter may have been high enough that actual collisions occurred. No more.
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}
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Re: APOD: Dark Matter in a Simulated Universe (2024 Oct 20)
They say an electric charge is conserved after a collapse to a black hole*. What if the dark matter possesses some kinds of dark charge and those are conserved in black holes too?Chris Peterson wrote: ↑Mon Oct 21, 2024 10:18 pmI don't think the concept of a dark matter black hole makes any sense. The nature of the matter is completely lost in a black hole. It's a singularity with mass. Why would one formed from baryonic matter be any different from one formed from dark matter?johnnydeep wrote: ↑Mon Oct 21, 2024 7:19 pmOk, thanks. That said, I understand there could very well still be as yet undetected (or undetectable) dark matter black holes, around which any dark matter particles could be interacting quite frequently.Chris Peterson wrote: ↑Mon Oct 21, 2024 1:37 pm
Except in actual usage, "temperature" simply isn't used that way. Absent a large enough population of particles for statistics to be meaningful, you would just consider the energy of a particle (which could be all over the place as it absorbs or emits photons and changes its energy state).
Particle collisions are extremely rare. At the particle scale, baryonic matter interacts with itself through the electromagnetic force. Not the very weak gravitational force. Very, very early in the Universe the particle density of dark matter may have been high enough that actual collisions occurred. No more.
For all we know the dark charges may interact in some strange way like neither mutually repel nor attract but chase one another or go around one another. It may help to sustain a puffy galactic dark halo even if the dark matter is not quite as non-colliding as they think. It may make darkly charged black holes interact and merge. But to study dark charges is a challenge for a baryonic creature like us.
___
* like there's a chance for electrically charged interstellar media to get together and feed a black hole
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Re: APOD: Dark Matter in a Simulated Universe (2024 Oct 20)
Well, pretty much by definition dark matter can't have an electric charge. To the extent black holes have any charge, it is by taking in charged material after formation. But any actual charge will be extremely tiny. Suffice to say, there's no reason to think that a black hole would vary in properties in some way based on the nature of the matter that formed it or feeds it.VictorBorun wrote: ↑Wed Oct 23, 2024 2:59 amThey say an electric charge is conserved after a collapse to a black hole*. What if the dark matter possesses some kinds of dark charge and those are conserved in black holes too?Chris Peterson wrote: ↑Mon Oct 21, 2024 10:18 pmI don't think the concept of a dark matter black hole makes any sense. The nature of the matter is completely lost in a black hole. It's a singularity with mass. Why would one formed from baryonic matter be any different from one formed from dark matter?johnnydeep wrote: ↑Mon Oct 21, 2024 7:19 pm
Ok, thanks. That said, I understand there could very well still be as yet undetected (or undetectable) dark matter black holes, around which any dark matter particles could be interacting quite frequently.
For all we know the dark charges may interact in some strange way like neither mutually repel nor attract but chase one another or go around one another. It may help to sustain a puffy galactic dark halo even if the dark matter is not quite as non-colliding as they think. It may make darkly charged black holes interact and merge. But to study dark charges is a challenge for a baryonic creature like us.
___
* like there's a chance for electrically charged interstellar media to get together and feed a black hole
Chris
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Re: APOD: Dark Matter in a Simulated Universe (2024 Oct 20)
Yes but I am talking about darkly charged BHs (if there are any kinds of dark charge, puffing up dark galactic halos maybe)Chris Peterson wrote: ↑Wed Oct 23, 2024 3:14 amWell, pretty much by definition dark matter can't have an electric charge. To the extent black holes have any charge, it is by taking in charged material after formation. But any actual charge will be extremely tiny. Suffice to say, there's no reason to think that a black hole would vary in properties in some way based on the nature of the matter that formed it or feeds it.VictorBorun wrote: ↑Wed Oct 23, 2024 2:59 amThey say an electric charge is conserved after a collapse to a black hole*. What if the dark matter possesses some kinds of dark charge and those are conserved in black holes too?Chris Peterson wrote: ↑Mon Oct 21, 2024 10:18 pm
I don't think the concept of a dark matter black hole makes any sense. The nature of the matter is completely lost in a black hole. It's a singularity with mass. Why would one formed from baryonic matter be any different from one formed from dark matter?
For all we know the dark charges may interact in some strange way like neither mutually repel nor attract but chase one another or go around one another. It may help to sustain a puffy galactic dark halo even if the dark matter is not quite as non-colliding as they think. It may make darkly charged black holes interact and merge. But to study dark charges is a challenge for a baryonic creature like us.
___
* like there's a chance for electrically charged interstellar media to get together and feed a black hole
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Re: APOD: Dark Matter in a Simulated Universe (2024 Oct 20)
"Dark charge"?VictorBorun wrote: ↑Wed Oct 23, 2024 6:28 amYes but I am talking about darkly charged BHs (if there are any kinds of dark charge, puffing up dark galactic halos maybe)Chris Peterson wrote: ↑Wed Oct 23, 2024 3:14 amWell, pretty much by definition dark matter can't have an electric charge. To the extent black holes have any charge, it is by taking in charged material after formation. But any actual charge will be extremely tiny. Suffice to say, there's no reason to think that a black hole would vary in properties in some way based on the nature of the matter that formed it or feeds it.VictorBorun wrote: ↑Wed Oct 23, 2024 2:59 am
They say an electric charge is conserved after a collapse to a black hole*. What if the dark matter possesses some kinds of dark charge and those are conserved in black holes too?
For all we know the dark charges may interact in some strange way like neither mutually repel nor attract but chase one another or go around one another. It may help to sustain a puffy galactic dark halo even if the dark matter is not quite as non-colliding as they think. It may make darkly charged black holes interact and merge. But to study dark charges is a challenge for a baryonic creature like us.
___
* like there's a chance for electrically charged interstellar media to get together and feed a black hole
Chris
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Re: APOD: Dark Matter in a Simulated Universe (2024 Oct 20)
Victor conjectured that dark matter might possess a "dark charge" in his prior post (which for some reason isn't appearing in my reply to your reply that does show it).Chris Peterson wrote: ↑Wed Oct 23, 2024 1:32 pm"Dark charge"?VictorBorun wrote: ↑Wed Oct 23, 2024 6:28 amYes but I am talking about darkly charged BHs (if there are any kinds of dark charge, puffing up dark galactic halos maybe)Chris Peterson wrote: ↑Wed Oct 23, 2024 3:14 am
Well, pretty much by definition dark matter can't have an electric charge. To the extent black holes have any charge, it is by taking in charged material after formation. But any actual charge will be extremely tiny. Suffice to say, there's no reason to think that a black hole would vary in properties in some way based on the nature of the matter that formed it or feeds it.
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}
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Re: APOD: Dark Matter in a Simulated Universe (2024 Oct 20)
Yeah, well maybe it possesses dark magnetism or dark unicorns. Making up a word without any underlying basis isn't science. Dark matter is understandable to the extent its observed behavior makes rational sense, and that is a particle of some kind that doesn't interact with the electromagnetic force (or only extremely weakly). If dark matter did interact with EM, that would be apparent in behavior that we explicitly do not observe, and would expect to.johnnydeep wrote: ↑Wed Oct 23, 2024 1:42 pmVictor conjectured that dark matter might possess a "dark charge" in his prior post (which for some reason isn't appearing in my reply to your reply that does show it).Chris Peterson wrote: ↑Wed Oct 23, 2024 1:32 pm"Dark charge"?VictorBorun wrote: ↑Wed Oct 23, 2024 6:28 am
Yes but I am talking about darkly charged BHs (if there are any kinds of dark charge, puffing up dark galactic halos maybe)
Chris
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Re: APOD: Dark Matter in a Simulated Universe (2024 Oct 20)
(And it seems that the quoting support only allows going three levels deep!)Chris Peterson wrote: ↑Wed Oct 23, 2024 1:46 pmYeah, well maybe it possesses dark magnetism or dark unicorns. Making up a word without any underlying basis isn't science. Dark matter is understandable to the extent its observed behavior makes rational sense, and that is a particle of some kind that doesn't interact with the electromagnetic force (or only extremely weakly). If dark matter did interact with EM, that would be apparent in behavior that we explicitly do not observe, and would expect to.johnnydeep wrote: ↑Wed Oct 23, 2024 1:42 pmVictor conjectured that dark matter might possess a "dark charge" in his prior post (which for some reason isn't appearing in my reply to your reply that does show it).
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}
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Re: APOD: Dark Matter in a Simulated Universe (2024 Oct 20)
the hole topic of any dark feed to black holes is poorly basedChris Peterson wrote: ↑Wed Oct 23, 2024 1:46 pmYeah, well maybe it possesses dark magnetism or dark unicorns. Making up a word without any underlying basis isn't science. Dark matter is understandable to the extent its observed behavior makes rational sense, and that is a particle of some kind that doesn't interact with the electromagnetic force (or only extremely weakly). If dark matter did interact with EM, that would be apparent in behavior that we explicitly do not observe, and would expect to.johnnydeep wrote: ↑Wed Oct 23, 2024 1:42 pmVictor conjectured that dark matter might possess a "dark charge" in his prior post (which for some reason isn't appearing in my reply to your reply that does show it).
one (rather weak) argument I thought of for a dark charge is "non-colliding" puffy dark halos around galaxies and clusters of galaxies.
Either dark particles only interact via gravitation or the dark charge acts puffing the heap up, with not mutual attraction but making dark particles chase one another or go around one another
the other (rather weak) argument I thought of for a dark charge is that the astrophysics currently struggles to model enough BHs' merges to explain why SMBHs are so many, and so massive, and so early. It would help if BHs could approach one another not only via their interaction with the stellar population but by stopping their orbiting because of some dark charge interaction. Say, their dark charges tell them to go around each other in one direction and their initial orbital spin after the first approach was in the opposite direction; those BHs would merge real fast.
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Re: APOD: Dark Matter in a Simulated Universe (2024 Oct 20)
It all sounds like pseudoscience to me.VictorBorun wrote: ↑Wed Oct 23, 2024 9:09 pmthe hole topic of any dark feed to black holes is poorly basedChris Peterson wrote: ↑Wed Oct 23, 2024 1:46 pmYeah, well maybe it possesses dark magnetism or dark unicorns. Making up a word without any underlying basis isn't science. Dark matter is understandable to the extent its observed behavior makes rational sense, and that is a particle of some kind that doesn't interact with the electromagnetic force (or only extremely weakly). If dark matter did interact with EM, that would be apparent in behavior that we explicitly do not observe, and would expect to.johnnydeep wrote: ↑Wed Oct 23, 2024 1:42 pm
Victor conjectured that dark matter might possess a "dark charge" in his prior post (which for some reason isn't appearing in my reply to your reply that does show it).
one (rather weak) argument I thought of for a dark charge is "non-colliding" puffy dark halos around galaxies and clusters of galaxies.
Either dark particles only interact via gravitation or the dark charge acts puffing the heap up, with not mutual attraction but making dark particles chase one another or go around one another
the other (rather weak) argument I thought of for a dark charge is that the astrophysics currently struggles to model enough BHs' merges to explain why SMBHs are so many, and so massive, and so early. It would help if BHs could approach one another not only via their interaction with the stellar population but by stopping their orbiting because of some dark charge interaction. Say, their dark charges tell them to go around each other in one direction and their initial orbital spin after the first approach was in the opposite direction; those BHs would merge real fast.
Chris
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Chris L Peterson
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