anti Dark Matter?

[chasmanian]

fascinating nFA. thank you.

and isn't it interesting that Black Stars may not need a singularity (solving that part of the problem)?

or are you talking about that when you mention the Planck Density?

for that matter, what does the Black Hole singularity problem come from?
is it that gravity at the BH center becomes infinite?
or something else becomes infinite? (and thus wrong?)

[notFritzArgelander]

fascinating nFA. thank you.

and isn't it interesting that Black Stars may not need a singularity (solving that part of the problem)?

yes. singularities always tell me that the theory is incomplete and inapplicable.

or are you talking about that when you mention the Planck Density?

for that matter, what does the Black Hole singularity problem come from?
is it that gravity at the BH center becomes infinite?
or something else becomes infinite? (and thus wrong?)

it's a mix.

even for a vacuum BH with not a speck of matter in it, say the non rotating Schwarzschild case for example, the singularity at the center is a place where the curvature of spacetime is infinite. so General Relativity fails at some point before the singularity is reached.

now for a BH made of matter or some other form of "stuff" the mass density also becomes infinite with the same conclusion.

so for a vacuum BH spacetime curvature becomes infinite, a big bugaboo.
for a matter BH both the spacetime curvature and the matter density become infinite. 2 big bugaboos for the price of one BH. such a deal!

[chasmanian]

thank you very much nFA.

so very interesting, all you wrote.

am thinking about neutron stars, etc now.

googling around, saw a comment somewhere, if you throw an apple onto a neutron star,
it will turn into a BH. hmmm.

and for your entertainment:

https://phys.org/news/2016-04-neutron-s ... -hole.html

https://en.wikipedia.org/wiki/Quark_star

"The existence of Planck stars was first proposed by Carlo Rovelli and Francesca Vidotto, who..."
https://en.wikipedia.org/wiki/Planck_star

[notFritzArgelander]

thank you very much nFA.

so very interesting, all you wrote.

am thinking about neutron stars, etc now.

googling around, saw a comment somewhere, if you throw an apple onto a neutron star,
it will turn into a BH. hmmm.

hmm indeed. it's not quite that simple. it has to be a maximum critical mass for that to happen. and whether or not it is maximum mass there will be fireworks from the apple. about 10% of the apple's rest mass will be converted into energy in the collision. so for a 100 g apple that is about a million billion joules of energy.

and for your entertainment:

https://phys.org/news/2016-04-neutron-s ... -hole.html

https://en.wikipedia.org/wiki/Quark_star

"The existence of Planck stars was first proposed by Carlo Rovelli and Francesca Vidotto, who..."
https://en.wikipedia.org/wiki/Planck_star

yep. great fun.

[chasmanian]

very good, thank you again nFA.

a million billion joules, wow.

this is from wiki:

https://en.wikipedia.org/wiki/Orders_of ... e_(energy)

1015 Peta- (PJ)
1×1015 J Yearly electricity consumption in Greenland as of 2008

[notFritzArgelander]

very good, thank you again nFA.

a million billion joules, wow.

this is from wiki:

https://en.wikipedia.org/wiki/Orders_of ... e_(energy)

1015 Peta- (PJ)
1×1015 J Yearly electricity consumption in Greenland as of 2008

.... or a 1 megaton nuke.

[chasmanian]

wiki:
"4.2×10^15 J Energy released by explosion of 1 megaton of TNT"

which would be 4 apples, but yeah wow, that is one heck of a lot of energy from 1 little piece of fruit.
hahaha
its reminding me of the Monty Python skit with John Cleese and the banana:

[chasmanian]

nFA,

would you please tell me if you have any thoughts about this?

could it be possible that Black Stars AND Black Holes both exist?

if yes, here is a thought experiment:

imagine if a Black Star and a Black Hole get close to each other.

if the Black Hole gets swallowed by the Black Star, we might be able to learn stuff about the Black Hole (and the Black Star)?

[notFritzArgelander]

nFA,

would you please tell me if you have any thoughts about this?

could it be possible that Black Stars AND Black Holes both exist?

My understanding is that it is not possible. The underlying physics requires either one or the other.

[notFritzArgelander]

nFA,

would you please tell me if you have any thoughts about this?

could it be possible that Black Stars AND Black Holes both exist?

My understanding is that it is not possible. The underlying physics requires either one or the other.

Let me correct that. I was wrong. There is a loophole. I've had a half cup of tea and realized my error.

Primordial vacuum BHs could coexist with Black Stars. Mergers of BHs and Black Stars would tell us more about the Black Stars than about the Black Holes. So far there is no way to tell apart mergers of vacuum BHs from mergers of non vacuum BHs.

[chasmanian]

super fantastic.
thank you for your super excellent thoughts nFA!!

[notFritzArgelander]

super fantastic.
thank you for your super excellent thoughts nFA!!

it's only when all BHs are made from matter that coexistence of BHs and Black Stars is impossible. just to emphasize.

[chasmanian]

thank you nFA.
I've been googling.

and found this article about Dark Stars. it mentions Dark Matter WIMP.
in case it is of value to you, I am posting a link:

https://astronomy.com/magazine/2018/09/ ... -the-light

here's a wiki:

https://en.wikipedia.org/wiki/Dark_star_(dark_matter)

[notFritzArgelander]

thank you nFA.
I've been googling.

and found this article about Dark Stars. it mentions Dark Matter WIMP.
in case it is of value to you, I am posting a link:

https://astronomy.com/magazine/2018/09/ ... -the-light

here's a wiki:

https://en.wikipedia.org/wiki/Dark_star_(dark_matter)

as long as googling keeps you giggling......

with the lack of evidence for WIMPs one must treat the Dark Star concept cautiously.

[chasmanian]

thank you nFA.

I super appreciate your wisdom and sense of humor.

[chasmanian]

you inspired me to try and craft a joke.
I have a start:

A Black Hole, a Black Star, a Dark Star, a Dark Energy Star, and a Gravastar walk into a bar.

no wait, they walk into a "bar"-red spiral galaxy.

hmm, will sleep on it.

[notFritzArgelander]

you inspired me to try and craft a joke.
I have a start:

A Black Hole, a Black Star, a Dark Star, a Dark Energy Star, and a Gravastar walk into a bar.

no wait, they walk into a "bar"-red spiral galaxy.

hmm, will sleep on it.

interesting premise.

[chasmanian]

thank you nFA.

this is the best I can think of for now.

and the bartender says: Cosmic Cocktails for the house

this is a book by Katherine Freese:

https://press.princeton.edu/books/paper ... c-cocktail

[notFritzArgelander]

It's nice, but I'm surprised she is still willing to believe in the DAMA results.

[GCoyote]

Sorry I'm late to the party. Is the reason for energy density always being positive a result of the photon being its own anti particle? Or am I confusing this with something else?