I Amount of black hole entropy inside the Universe?

AI Thread Summary
The majority of the universe's entropy is believed to reside in black holes, with estimates suggesting stellar-mass black holes have an entropy of around 10^98 bits. The cosmic microwave background radiation contributes significantly to the universe's entropy, estimated at about 10^90 bits. Understanding the absolute entropy of the rest of the universe involves calculating the entropy of ordinary matter and photons, which are well-defined. The discussion emphasizes the importance of references for claims made about entropy comparisons. Overall, black holes are considered stable due to their high entropy, aligning with the Second Law of Thermodynamics.
bbbl67
Messages
216
Reaction score
21
Now, it's been said that the majority of the entropy in the universe resides within the cumulative entropy of black holes inside the universe. How do they know that?
Now, I'm not so interested in how they determine the black hole's entropy, I know there's a relatively simple formula for that. What I'm curious to know is how do they know what the absolute entropy of the rest of the universe is to compare it to the black holes within it?
 
Astronomy news on Phys.org
bbbl67 said:
Now, it's been said
By whom? Where?
 
  • Like
Likes jim mcnamara and malawi_glenn
In order to answer we need references please.
 
Please PM me when you have the reference you wish to discuss and I will reopen the thread for you. In the meantime, I have closed it to reduce the number of “we need references” replies
------------------------------------------------------------------
The OP has a reference and the thread is reopened
 
Last edited:
  • Like
Likes jim mcnamara
Here's the reference:
Entropy in the Universe | Azimuth
https://johncarlosbaez.wordpress.com/2020/01/25/entropy-in-the-universe/

The entropy in all the photons in the Universe is even more! The Universe is full of radiation left over from the Big Bang. The photons in the observable Universe left over from the Big Bang have a total entropy of about 1090 bits. It’s called the ‘cosmic microwave background radiation’.

Black holes have immensely more entropy than anything listed so far. Egan and Lineweaver estimate the entropy of stellar-mass black holes in the observable Universe at 1098 bits. This is connected to why black holes are so stable: the Second Law says entropy likes to increase.
 
bbbl67 said:
how do they know what the absolute entropy of the rest of the universe is
Because we know what "the rest of the universe" is made of: ordinary matter and photons. And we know how to calculate the entropy of those things.
 
TL;DR Summary: In 3 years, the Square Kilometre Array (SKA) telescope (or rather, a system of telescopes) should be put into operation. In case of failure to detect alien signals, it will further expand the radius of the so-called silence (or rather, radio silence) of the Universe. Is there any sense in this or is blissful ignorance better? In 3 years, the Square Kilometre Array (SKA) telescope (or rather, a system of telescopes) should be put into operation. In case of failure to detect...
Thread 'Could gamma-ray bursts have an intragalactic origin?'
This is indirectly evidenced by a map of the distribution of gamma-ray bursts in the night sky, made in the form of an elongated globe. And also the weakening of gamma radiation by the disk and the center of the Milky Way, which leads to anisotropy in the possibilities of observing gamma-ray bursts. My line of reasoning is as follows: 1. Gamma radiation should be absorbed to some extent by dust and other components of the interstellar medium. As a result, with an extragalactic origin, fewer...
This thread is dedicated to the beauty and awesomeness of our Universe. If you feel like it, please share video clips and photos (or nice animations) of space and objects in space in this thread. Your posts, clips and photos may by all means include scientific information; that does not make it less beautiful to me (n.b. the posts must of course comply with the PF guidelines, i.e. regarding science, only mainstream science is allowed, fringe/pseudoscience is not allowed). n.b. I start this...
Back
Top