/sci/ - Science & Math

>>9373404
>Entropy
No such thing.

>>9373407
:O

>>9373407

>>9373404
t. Sophomore

>>9373404
Any non-BH object with the same mass as a particular BH must have a lower entropy than the BH.
Entropy is sort of a measure of "what you don't know." An ordered deck of cards can be described in a few works. There's not much you don't know.
A shuffled deck takes a lot more verbiage to completely describe. There's a great deal you don't know.
You don't know ANYTHING about what's inside an event horizon. All properties but mass, and spin, and charge disappear at the boundary. You can't know less than zero about something -- so BHs have the maximum possible entropies.

>>9373404 (OP)
Any non-BH object with the same mass as a particular BH must have a lower entropy than the BH.
Entropy is sort of a measure of "what you don't know." An ordered deck of cards can be described in a few words. There's not much you don't know.
A shuffled deck takes a lot more verbiage to completely describe. There's a great deal you don't know.
You don't know ANYTHING about what's inside an event horizon. All properties but mass, and spin, and charge disappear at the boundary. You can't know less than zero about something -- so BHs have the maximum possible entropies.

>>9373448
Thanks, cobber. That's a good explanation.

>>9373448
So do black holes evaporating make entropy go up?
I don't have a brainlet macro for my post, just use this one. >>9373412

>>9373461
Go down I mean.

>>9373404
Low entropy, they evaporate over time.

>>9373461
>>9373465
>>9373472
That's an interesting point.

Does the evaporation via Hawking radiation lower the entropy?

>>9373404
>low entropy
>high entropy

It is the exact same thing, that fucking brainlet.

>>9373491
The jars looks different to me.

>>9373493

* Munches popcorn, watches posers 'discuss' things they don't understand or know anything about, including even what the words mean. *

>>9373483
count it yourself

http://xaonon.dyndns.org/hawking/

>>9373528
Most of us are asking questions, one guy gave an answer, and everyone else is just saying "Haha you don't know but I do, I swear"

So sure, do whatever buddy.

>>9373483
>Does the evaporation via Hawking radiation lower the entropy?

>>9373448
>Entropy is sort of a measure of "what you don't know."

Stop begging the question, OP.

grammarist.com/rhetoric/begging-the-question-fallacy/

>Begging the question, sometimes known by its Latin name petitio principii (meaning assuming the initial point), is a logical fallacy in which the writer or speaker assumes the statement under examination to be true. In other words, begging the question involves using a premise to support itself.

A black hole is not "infomation-dense" any more than it has "rotational-velocidensity". That's just a made up word. In terms infomation crammed into a small space, a typical hardrive with a compression algorithm has more information space in it than any celestical object.

>>9373407
Could you please go back to your nursery?

>>9373528
Why dont you fuck off you chad shit.

>>9373448
Isn't entropy more of a measure of "happenedness"; where a black hole is maximally static?

I seriously dont get how you get from log of multiplicity of a system to a fucking black hole. Given that we dont know the multiplicity and entropy has to be maximized to conserve energy I dont see a way to reasonably decide based on basic thermodynamics and thats where

https://en.m.wikipedia.org/wiki/Black-hole_thermodynamics

comes into picture and apparently entropy of black hole is proportional to its surface area

>>9373404
I'm non-physics brainlet here
can anyone explain me the whole "information and black holes" schtick?
I think of "information" as an abstract, non-physical concept, how does gravity/mass affect it?

>>9373404
>entrophy
kys my man

>>9373404

>>9374179
https://youtu.be/JalSUkondr8

>>9374179
A black hole's radius is the length of its singularity to the event horizon.
You just havent comprehended the concept clearly.

>>9373404
Maximum entropy, see: https://en.wikipedia.org/wiki/Bekenstein_bound

>>9374179
>>9374181
>>9374192
https://youtu.be/U9wDxktPx4k

>>9373407
Look around in your basement: Thát's entropy, neckbeard.

>>9374100
>entropy of black hole is proportional to its surface area

>surface area decreases
>entropy decreases

Woops

Everyone in here who has to use analogies or quotation marks to describe entropy has no qualifications to talk about it at all and should (re)read fundamental literature.

>>9373404
That isn't entropy. Simple mixing or disorder is not entropy. It is a mathmatical state regarding the distribution of energy into stable states the represent a local minima.

>>9373448
>Entropy is sort of a measure of "what you don't know."
no it isn't. Entropy describes the energy difference between the current state and the theoretical "stable ground state" where no further work can be extracted from the system.

>>9374100
Nope, the energy of a black hole is proportional to its mass and volume. The entropic state of a black hole is a maximum entropy. You cannot extract work from a system that only includes a single black hole.

Black holes can lose energy through Hawking radiation, but if you put a radiation mirrior around a black hole it would be steady state forever.

>>9373528
just explain it thoroughly and then leave, don't even look at the responses. If you're actually a grad student or have a physics PhD then you should be able to do so easily.

>>9373407
This. Entropy is a spook.

A curious question.
Can black holes with different masses have different volumes?
And which is the mass and volume relationship?
What about the no hair theorem.

>>9373461
>>9373483
>>9373407

W H A T I S G I B B S E N E R G Y ? ? ?

>>9373404
I'd say you could replace entropy with density, and make them limits.

>>9373483
>Does the evaporation via Hawking radiation lower the entropy?

It lowers the entropy of the universe. The BH has a maximum entropy density; it is a state of maximum entropy for a given volume (the volume inside the event horizon). However, the universe is much larger, and is not in a maximum-entropy-density state.

The evaporation increases total entropy by putting particles into states outside the event horizon. The remaining mass of the black hole is lower, so its event horizon shrinks. The black hole's total entropy thus decreases, but the universe's entropy increases by more than enough to compensate. It's essentially the same idea as how a blackbody such as a star cools by radiation: its entropy drops but the total entropy of the system rises because of the entropy in the radiation.

>>9377556
>It lowers the entropy of the universe.
Sorry: meant to say it *increases* the entropy of the universe.

>>9377556
>The black hole's total entropy thus decreases, but the universe's entropy increases by more than enough to compensate
That's interesting, thank you.

>>9377298
The other guy said a blackhole was max entropy though.

>>9374911
>proportional to it's mass and volume

So the wiki page is wrong then? I don't think proportionality to mass and volume is correct. At best, It's square of the mass of black hole.