Recent content by One128

First, any increase in energy/mass would be due to increased temperature; after the heat dissipates and the stick returns to environment temperature, you'll find its energy/mass unchanged. - That there isn't a lasting increase in energy is obvious if you consider that an idealized stick with a...

If I know you're sending me the result of 30 coin tosses, and nothing else, then the entropy of such a message - until I receive it - is 30 bits, and I can't tell the value of any bit. After I receive it, the entropy of the same message is zero, and I can tell the value of every bit. If I don't...

Entropy is the measure of uncertainty, and as such it is ultimately defined the same way in information theory as in statistical mechanics: as a measure of uncertainty. I believe I may have mentioned that a few times. The crucial thing is: the uncertainty about what, given what. That makes all...

More accurately, entropy (in thermodynamic sense) does not quantify how many states the particles do occupy, but how many states they can occupy, in a given macrostate. In a system where 0's and 1's are encoded symmetrically (same energy level etc.), particles can occupy the same number of...

I'm not sure what point you're trying the make here. If I understand correctly, you seem to be essentially saying the participating in a process that involves flow of heat can have entropy effects on the material. Putting aside whether that is the case or not - how would that support any point...

I don't understand what you're referring to (i.e. what doesn't follow from what and why). If by "first paragraph" you mean the one you quoted, then I don't see how the statement that change in entropy depends on how you define entropy has anything to do with Clausius-Duhem inequality.

Q_Goest, I apologize, I skimmed through your post too fast and I overlooked the details of your particular setup. Upon closer reading, I realize that it's actually not that straightforward to answer: This can't be answered given only the details you give. If the gas was an ideal gas, 1 and 2...

Only for the same set of macroscopic variables and the same assumptions about the observer. The change of entropy does depend on how we specify it. As noted in the example I just wrote, in one instance reading the data does not decrease the entropy, in another instance it can. Once again, you...

Yes, this is true, as long as certain assumptions are satisfied (namely the fundamental assumption of statistical mechanics, i.e. all microstates being equally likely) and the temperature is constant. It can be also looked at in this way: increasing entropy means that some of the usable energy...

Let me see if I can address that, and let me start with a somewhat different example, that may illustrate it better, but also say how your example fits into that. Say you have a large bottle of hydrogen, separated into two chambers. In one, the gas is hot, in the other one, the gas is cold. You...

Well, let me try to clarify: the OP does ask about the difference in weight between an empty and a full memory stick, so yes, in order to truly answer that, one should first define what "empty" and "full" means, in terms of data. But the question is related to a more general one: does the mass...

The problem with that is that the relationship between energy, entropy and temperature follows from the assumption that all microstates are equally likely - i.e. that you don't in fact know anything about them (see here for how that assumption is used). So when you say, "a change of entropy at...

Entropy and equilibrium are both observer dependent. The classical example of this is the mixing paradox. You mix two substances at the same temperature and pressure; does the entropy change? If you're not able to tell the difference between the substances, then there's no change in entropy, and...

Kote is absolutely right. Andy, you seem not to realize that entropy depends on the observer. Entropy is a measure of our uncertainty about a system - i.e., the uncertainty of some particular observer. For two different observers, the entropy of a system can differ. See for example the...

When a valve on a pneumatic tire (filled with compressed air) is released and the tire is allowed to deflate, one may notice that the valve stem will become quite cold during the process. A common, everyday observation. So far, so good. The question is: What would we observe if the tire being...