I think you are thinking of the thought experiment as some sort of representation of reality, possible reality or the like. Many make this mistake in thinking about what a thought experiment "does", aka it's function. Physicist like to think and math about what they think. If you rewatch this video you will see how this 19th century idea from Maxwell has led to a number of ideas, most notably linking information theory and thermodynamics. That is the function of this kind of thought experiment, to challenge current ideas and to produce new ones. Still, keep physicsing. It's good for your brain. 😊
The demon must sense. It needs an interaction to do this. An interaction implies 2, not one, particles. The problem, unknown to Maxwell, is the transfer of heat by the interaction. a la Szilard.
Why didn't Szilard simply argue that, in order to measure the position and velocity of the particle, the demon has to introduce energy to the system, making it, by definition, an open system? Increased entropy is fine in open systems.
globally as in "on the entire system", yes, in our physical universe that means it doesn't necessarily apply locally, since the "system" in question is always the entire universe (you can never fully isolate yourself from the outside world), but in a thought experiment like this, the entire system was the box in question, which was what was observed
@@user-zz3sn8ky7z However, unless there's more to it, the thought experiment doesn't prove anything about the 2nd law if one of the conditions is that the 2nd law is modified so that it only applies to part of the system. Then it just says "if we alter the laws of thermodynamics the laws of thermodynamics are now different". Of course it's still interesting, since it shows that the increase in entropy to make this consistent with actual thermodynamics it provided by the exchange of information itself (which is quite interesting), but it doesn't do what it was intended to do.
Couldn't we construct a gate that only lets through fast particles from one direction and reflects them from the other direction? No demon needed, just the physical properties of such a gate. It's pretty much safe to say that the 2nd law is true, so we should be able to find why such a gate is impossible.
Well, those physical properties sound a lot like magic until someone figures out how to do it (if it's possible that is), it doesn't really change the argument compared to the demon. In a way, those hypothetical physical properties _are_ the demon. And why is it safe to say that the 2nd law is always true? We don't know if we have simply failed to break it so far, or if it's truly impossible. Since the universe exists, it seems a lot of stuff (spacetime, matter) was created from nothing at some point...
@@Takyodor2 well, afaik we only know we know nothing, but we got to establish our known reality. Doesn't mean that knowledge can change or mutate. But the 2nd law is solid if the only argument is a magical door
Why is it so hard for people to look up how to pronounce Hungarian names correctly? It's not "zillard", it's "See-lard"! In Hungarian, the double letter "sz" is pronounced as "s", while a simple "s" is pronounced "sh". It takes 1 minute to look it up and people can never get them right.
I never really properly understood this thought experiment because, to me, Maxwell's Demon is unphysical and, therefore, akin to _just magic_
The entire argument is just "God can violate the second law if he wants to lol"
I think you are thinking of the thought experiment as some sort of representation of reality, possible reality or the like. Many make this mistake in thinking about what a thought experiment "does", aka it's function.
Physicist like to think and math about what they think. If you rewatch this video you will see how this 19th century idea from Maxwell has led to a number of ideas, most notably linking information theory and thermodynamics.
That is the function of this kind of thought experiment, to challenge current ideas and to produce new ones.
Still, keep physicsing. It's good for your brain. 😊
@@puernatura8998 It was originally described as a "finite being" per Maxwell's own description.
The demon must sense. It needs an interaction to do this. An interaction implies 2, not one, particles. The problem, unknown to Maxwell, is the transfer of heat by the interaction. a la Szilard.
What about gate which opens by itself BUT the energy go calculate position and velocity of molecule is taken from the system itself
Entropy with energy units?
Why didn't Szilard simply argue that, in order to measure the position and velocity of the particle, the demon has to introduce energy to the system, making it, by definition, an open system? Increased entropy is fine in open systems.
How come just saying "there is no such thing as a frictionless door" is not enough to disprove the assumption?
Are you sure about the units?
[S] =J/K
[kT]=J
Isn't the second law meant to only apply globally?
globally as in "on the entire system", yes, in our physical universe that means it doesn't necessarily apply locally, since the "system" in question is always the entire universe (you can never fully isolate yourself from the outside world), but in a thought experiment like this, the entire system was the box in question, which was what was observed
@@user-zz3sn8ky7z However, unless there's more to it, the thought experiment doesn't prove anything about the 2nd law if one of the conditions is that the 2nd law is modified so that it only applies to part of the system. Then it just says "if we alter the laws of thermodynamics the laws of thermodynamics are now different".
Of course it's still interesting, since it shows that the increase in entropy to make this consistent with actual thermodynamics it provided by the exchange of information itself (which is quite interesting), but it doesn't do what it was intended to do.
It is meant to apply to closed systems.
@@brendanh8193 that's the same thing
Couldn't we construct a gate that only lets through fast particles from one direction and reflects them from the other direction? No demon needed, just the physical properties of such a gate. It's pretty much safe to say that the 2nd law is true, so we should be able to find why such a gate is impossible.
Well, those physical properties sound a lot like magic until someone figures out how to do it (if it's possible that is), it doesn't really change the argument compared to the demon. In a way, those hypothetical physical properties _are_ the demon. And why is it safe to say that the 2nd law is always true? We don't know if we have simply failed to break it so far, or if it's truly impossible. Since the universe exists, it seems a lot of stuff (spacetime, matter) was created from nothing at some point...
@@Takyodor2 well, afaik we only know we know nothing, but we got to establish our known reality. Doesn't mean that knowledge can change or mutate. But the 2nd law is solid if the only argument is a magical door
@@SiriusJazz A magical door, and also the existence of the universe and its contents.
Search for Maxwell's demon turbine or Evosmosis Engine
Beautiful
Why is it so hard for people to look up how to pronounce Hungarian names correctly? It's not "zillard", it's "See-lard"! In Hungarian, the double letter "sz" is pronounced as "s", while a simple "s" is pronounced "sh".
It takes 1 minute to look it up and people can never get them right.