Black holes and the first law of thermodynamics

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Summary:

Is matter consumed by a black hole truly destroyed, or?...
The first law of thermodynamics states that matter can only be transferred from one state to another, and cannot be truly destroyed.

What happens to matter consumed by a black hole? What happens to it and where does it go? Does the first law still hold true?
 

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Orodruin
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The first law of thermodynamics states that matter can only be transferred from one state to another, and cannot be truly destroyed.
It does not state this. It relates internal energy of an isolated system to work done and heat.
 
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  • #3
stefan r
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Does the first law still hold true?
yes
The first law of thermodynamics states that matter can only be transferred from one state to another, and cannot be truly destroyed.
Matter and energy are interchangeable. What goes into a black hole stays in a black hole. It is still spinning and has charge. You can take angular momentum from a black hole. Some Hawking radiation may come out. But things that went in are gone. We will never get information from them.

What happens to matter consumed by a black hole? What happens to it and where does it go?
It goes into the black hole. It stays right there. That is the end destination.

Over obscene time scales the black hole may radiate enough energy to be equal to the mass that fell in. On Earth we use a platinum bar located in a vault in France to measure a kilogram. This platinum will quantum decay much faster then any stellar mass black holes. The black hole is going no where on the timescale of our finest instruments. It is the ultimate ground state. You cannot go any lower.
 
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Orodruin
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On Earth we use a platinum bar located in a vault in France to measure a kilogram.
No we do not. Not since the SI units were redefined two weeks ago.
 
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Matter and energy are interchangeable.
It depends on how you define matter, but still it is very misleading. The way people usually define matter makes it a "thing", and energy is a property of that thing. Things and their properites are not interchangable.
 
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It depends on how you define matter, but still it is very misleading. The way people usually define matter makes it a "thing", and energy is a property of that thing. Things and their properites are not interchangable.
The important bit in this is "...define matter...". Physicists don't usually define "matter", they talk about the properties of matter, which include mass and energy, (and spin... charge...). You can make a good argument that the only things that actually exist are the properties. At a particle level these are quantum numbers. When we are talking about mass and black holes the only way that counts (I nearly wrote 'matters') is the definition in General Relativity with mass and energy interchangeable. Everything else , including "The way people usually define ...", is only an approximation/guesswork.
In the case of a black hole, the sets of numbers which are particles end up on the other side of the event horizon from whence we can never recover them.
 
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Matter and energy are interchangeable.
Well I think what he meant to say is that mass and energy are interchangeable when anything can move at a speed which can be compared to the speed of light.
Summary: Is matter consumed by a black hole truly destroyed, or?...

What happens to matter consumed by a black hole?
Well everything that goes into the blackhole stays in the blackhole. the blackhole starts gaining mass and some Hawking radiation may be released in these cases. and yeah the matter that goes into the blackhole is destroyed to its atom and then the atoms start moving in the blackhole creating more mass as stated above.

Somethings I said may be wrong so sorry for that and tell me where I am wrong. Thanks
 
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Orodruin
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and yeah the matter that goes into the blackhole is destroyed to its atom and then the atoms start moving in the blackhole creating more mass as stated above.
This is wrong and you simply cannot state this. If you are not reasonably certain of your statements then you should not be making them. It will just confuse and mislead others.
 
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@ElliotSmith, it is a few years old, but Brian Koberlein gives a good treatment of black hole thermodynamics at https://phys.org/news/2014-09-black-hole-thermodynamics.html, with some follow-on articles that delve into specific aspects such as 'hair', in-falling matter, and light orbiting a BH. He does not go into math, so it may not be as detailed as you are seeking, but it seems to address your question at a conversational level.
 
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Physicists don't usually define "matter"
But still they think about it as a 'thing', and energy is a property of that thing, so you can't say that matter and energy are interchangable just like 'strawberry' and 'red' are not interchangable.

they talk about the properties of matter
And properties of matter are not the same as matter. I know it's semantics, but I think that these semantics are very important. Especially when there are so many misconceptions about mass and energy in relativity. For example this:

is the definition in General Relativity with mass and energy interchangeable.
as is stated is not true (unless you use an outdated concept of relativistic mass). Mass (meaning invariant mass) of a system depends on it's energy, of course, but that does not mean that mass and energy are interchangable. Proper relation between mass and energy of a particle looks like this (setting ##c=1##) : ##E^2=p^2+m^2##. It contains momentum!
 
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Summary: Is matter consumed by a black hole truly destroyed, or?...

The first law of thermodynamics states that matter can only be transferred from one state to another, and cannot be truly destroyed.

What happens to matter consumed by a black hole? What happens to it and where does it go? Does the first law still hold true?
While this thread is marked basic, you still might find this old library entry regarding black hole thermodynamics useful-

https://www.physicsforums.com/threads/black-hole-thermodynamics.762982/
 

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