It's my understanding the general mechanism of core collapse involves the adiabatic constant of the material, gamma. This is the exponent in the relation P V^(gamma) = constant.
For a normal, non-relativistic gas in which the particles have no internal degrees of freedom, gamma is 5/3. As a gas becomes more relativistic, and as photon pressure becomes more important, gamma declines toward 4/3.
For gamma = 4/3, a self-gravitating gas will be marginally stable: the energy needed to compress a sphere of the gas will be equal to the gravitational potential energy liberated by the compression. So, any effect that pushes gamma below 4/3 makes it unstable against collapse.
In a conventional core collapse SN this is photodissociation of nuclei, where energy gets soaked up in breaking apart nuclei into alpha particles and then free nucleons. In a pair-instability SN, this is increasing conversion of photons to electron-positron pairs.
ben_w 13 hours ago [-]
My favourite kind of supernova, due to their absurdity.
chasil 10 hours ago [-]
A hypernova is an even larger star that is theorized to end its life due to photodisintegration rather than pair instability.
I just want to live long enough for space telescopes to evolve exponentially to observe kilonovas in the visual spectrum
I mean laser interferometers are an amazing advancement but just imagine seeing an earth-sized chunk of gold pop out of a kilonova (probably not my lifetime but eventually a human will see it happen)
Thank goodness this administration did not frack with Nancy Grace Roman Telescope, I thought the name alone would make them cancel it or rename it after him, wait maybe I shouldn't even mention that idea...
Check out the aragoscope [1]. It's not planned, but we would already have the technology as it doesn't rely on fragile and heavy lenses to be sent in orbit.
If you look at image 17 you can see that a simulated aragoscope that is in our technical reach could already resolve the Jupiter moons from almost 23 light years away. I hope as well that we will have something comparable while I am still around.
I know you are a bad-faith bot account, so this is not posed to you.
I am wondering why there are so many of these accounts popping up. They seemingly only exist to antagonize. What do their operators get out of that?
junon 18 hours ago [-]
What do 14 year olds get out of trolling anything? A cheap grin and something to do on an after school evening.
detritus 17 hours ago [-]
heh, funny you say that - I just yesterday almost bit at some obvious Nego-Trolling on here and remembered "Just don't engage".
Some people, for some reason at certain points in their life, just want to shit on other people's stuff, any way that they can, for... reasons.
I mean, clearly it's not to make themselves feel better, because how on Earth could that work?
There's no value in engaging, in any way whatsover. Sadly there's very little that can be done to prevent that form of human behaviour, without otherwise souring the experience for the generality.
*shrug, whatchagonnado?
nutjob2 17 hours ago [-]
> I mean, clearly it's not to make themselves feel better, because how on Earth could that work?
When you're really, really angry you look for an outlet. Some people kick the dog, some abuse their gf/wife/kids, others troll on online forums.
detritus 17 hours ago [-]
Yeah, I get that. But does it actually make them feel better?
What do they say about sugaring trauma?
AnimalMuppet 17 hours ago [-]
It can make them feel better by giving them a chance to look down on someone else. (The "looking down" doesn't have to be the content of the post - the act of trolling is a form of looking down on someone.)
scns 16 hours ago [-]
> It can make them feel better by giving them a chance to look down on someone else.
That's the idea but it does not work. Self esteem is still negative afterwards
MadnessASAP 13 hours ago [-]
Whether or not it works isn't what matters. It's whether or not the perpetrator, consciously or not, believes it works.
nutjob2 17 hours ago [-]
Welcome to the general public. You'll meet all the people you go to great lengths to avoid in the real wold, online.
timwis 17 hours ago [-]
Dark Forest theory, anyone?
groos 17 hours ago [-]
It was a supergiant, hence died at a young age, and unlikely to have evolved life of any kind in its system.
tgrowazay 16 hours ago [-]
That’s what Singer’s civilization wants you to think before they send a Photoid or Dual-Vector foil (but later would require a supervisor’s approval which is a PITA)
dotancohen 13 hours ago [-]
> before they send a Photoid
Plenty of services require a Photo ID nowadays.
veltas 2 hours ago [-]
I like to think there's a solid argument against dark forest that even if you can destroy other intelligent systems, then hidden intelligent cautious systems may exist and see evidence of what you've done, so there's a potential consequence to destroying every intelligent system you identify.
And then also (maybe this is absurd) isn't there something intrinsic in intelligence to want to avoid conflict and desire peace?
chasil 14 hours ago [-]
Pair-instability can only happen in low-metalicity surroundings.
The big bang created hydrogen, helium, and small amounts of lithium. Any higher elements are created by stars, and a significant presence of those "metals" will take a star down a different path than pair-instability.
Low-metalicity environments are not likely to be friendly to life.
[1] https://en.wikipedia.org/wiki/Spontaneous_combustion
https://en.wikipedia.org/wiki/Pair-instability_supernova
For a normal, non-relativistic gas in which the particles have no internal degrees of freedom, gamma is 5/3. As a gas becomes more relativistic, and as photon pressure becomes more important, gamma declines toward 4/3.
For gamma = 4/3, a self-gravitating gas will be marginally stable: the energy needed to compress a sphere of the gas will be equal to the gravitational potential energy liberated by the compression. So, any effect that pushes gamma below 4/3 makes it unstable against collapse.
In a conventional core collapse SN this is photodissociation of nuclei, where energy gets soaked up in breaking apart nuclei into alpha particles and then free nucleons. In a pair-instability SN, this is increasing conversion of photons to electron-positron pairs.
https://en.wikipedia.org/wiki/Photodisintegration#Hypernovae
I mean laser interferometers are an amazing advancement but just imagine seeing an earth-sized chunk of gold pop out of a kilonova (probably not my lifetime but eventually a human will see it happen)
Thank goodness this administration did not frack with Nancy Grace Roman Telescope, I thought the name alone would make them cancel it or rename it after him, wait maybe I shouldn't even mention that idea...
* https://science.nasa.gov/mission/roman-space-telescope/
* https://en.wikipedia.org/wiki/Nancy_Grace_Roman_Space_Telesc...
If you look at image 17 you can see that a simulated aragoscope that is in our technical reach could already resolve the Jupiter moons from almost 23 light years away. I hope as well that we will have something comparable while I am still around.
[1] https://www.nasa.gov/wp-content/uploads/2017/03/2014_phase_i...
For reference, there are 103 known main sequence stars within 20 light years.[1]
[1]: https://en.wikipedia.org/wiki/List_of_nearest_stars
I don't think it's possible to do worse, even for him.
I am wondering why there are so many of these accounts popping up. They seemingly only exist to antagonize. What do their operators get out of that?
Some people, for some reason at certain points in their life, just want to shit on other people's stuff, any way that they can, for... reasons.
I mean, clearly it's not to make themselves feel better, because how on Earth could that work?
There's no value in engaging, in any way whatsover. Sadly there's very little that can be done to prevent that form of human behaviour, without otherwise souring the experience for the generality.
*shrug, whatchagonnado?
When you're really, really angry you look for an outlet. Some people kick the dog, some abuse their gf/wife/kids, others troll on online forums.
What do they say about sugaring trauma?
That's the idea but it does not work. Self esteem is still negative afterwards
And then also (maybe this is absurd) isn't there something intrinsic in intelligence to want to avoid conflict and desire peace?
The big bang created hydrogen, helium, and small amounts of lithium. Any higher elements are created by stars, and a significant presence of those "metals" will take a star down a different path than pair-instability.
Low-metalicity environments are not likely to be friendly to life.