23966k - Instituto Carlos I - Universidad de Granada

very nice to do experiments because it’s very clear this W function what it means, and I
think it would be nice to see more experiments on measuring these state functions [. . . ]
experimentally.
• JLL: I guess that’s a joint work with Tasaki also.
• FR: Yes, well this Tasaki you mention, I think is slightly bit different, because I’m not
sure they are the same people. I think they are Japanese but not the same. It’s a different
work.
• JLL: I think it is certainly a very interesting work.
• SP: It is just my ignorance. What do you define to be a steady state? Because,
obviously, may have a bit of fluctuations. How big the fluctuations do you allow?
• JLL: It’s like in an equilibrium state. I mean, in the region which Shelly [Goldstein]
showed, or I showed also, we do include fluctuations of square root of N type of thing.
In the steady state they might be different, but normal fluctuations I would include in.
• SP: So, for example, if instead of the metal bar you just have a cube with water and a
bit of carbon and hydrogen, eventually you will get a fish. So, if instead of being a metal
bar you have a cube that is filled with a homogeneous solution of water, and carbon and
hydrogen, after a long time you will get a fish swimming. That is a too big fluctuation.
• JLL: I think so. I think that is a too big fluctuation. I would consider that as different
macrostates.
• SP: So although are on average, say, a thousand fish swimming, that would not be a
steady state.
• JLL: Yes, I mean, let’s stick to the metal bar. Or let’s take still water where there is not
going to be any fish swimming over there. I you have got a fish swimming, presumably
you have put in something besides just water. [. . . ]
• SP: Some Carbon, some Hydrogen, and it’s homogeneous but eventually there will be
a fluctuation that will lead you to. . .
• JLL: Wouldn’t that be true in equilibrium also? You also have a fluctuation that will
lead you to something like that?
• SP: Suppose that this will be maintained for a long time. Suppose this situation will
be. . . Well, the other interesting question is obviously whether there is a limit to the
complexity that may arise in such a system.
• JLL: I don’t know the answer to that. But I think somebody asked me again in
connection with your question on Monday. What is the steady. . . ? Who is that? Julio
[Fernández]? was asking me the question: what is the steady state of us on Earth
assuming that the sun doesn’t give out on us, or other thing. What’s going to happen?
My private opinion maybe I don’t want to tell you [laughs]. But, I don’t know. I mean,
things can be very, very complex as you say, and specially in nonequilibrium situations.
It’s a good point.
• Anonymous: You can find it through the hydrodynamic equations. So you start with
the hydrodynamic equations, and you set the time derivative equal to zero. This is the
way, one of the ways, in which you can identify these states.
• JLL: Macroscopic, but still it doesn’t include everything. Anybody else?
• Sergey Apenko: I have a kind of a technical question because I’m not an expert in the
field. I feel that the whole discussion is somehow predetermined by these three questions
put forward. They are certainly very fundamental and very difficult to solve. But it’s
written here that these are only some of important open problems. I have a question: do