91–100 of 178 posts
So the law of increasing entropy is not a fundamental law of the reality because it can be derived from other fundamental equations. Suppose I show you a snapshot of a random universe, would you be able to tell if the entropy of the universe is going to increase or decrease as the time progresses? Let's assume that universe's entropy would increase. Consider another universe exactly the same as current universe, but…
So, the sun is a low-entropy source of energy, and Earth (and everything on it) increases that entropy as it uses and then reradiates that energy. This process is entirely consistent with the second law of thermodynamics.
The relationship between light frequency and entropy comes from the fact that entropy is a measure of disorder or randomness. High-frequency light, such as ultraviolet or visible light, is more ordered and less random than lower-frequency light, such as infrared or microwave light.
This is due to how light is structured. Light is made up of particles called photons, and each photon carries a certain amount of energy. The energy of a photon is directly proportional to its frequency: higher-frequency photons carry more energy than lower-frequency ones.
So, if you have a fixed amount of energy to distribute among photons, you can do so in many more ways (i.e., with higher entropy) if you use low-energy, low-frequency photons. That's because you would need many more of them to carry the same total amount of energy.
On the other hand, if you use high-energy, high-frequency photons, you would need fewer of them to carry the same total amount of energy. There are fewer ways to distribute the energy (i.e., lower entropy), so this arrangement is more ordered and less random.
Therefore, high-frequency light is considered a lower-entropy form of energy compared to low-frequency light, because the energy is concentrated in fewer, more energetic photons.
Earlier quoted context omitted.
What I really like about this explanation is that it highlights the fact that entropy is not a natural property of the physics system: entropy is only defined with respect to some coarse-graining operation applied by an imperfect observer of the system. So as Sabine points out it seems we should really be talking about multiple different entropies, each of which corresponds to a different mechanism for coarse-grainin…
> mass-spring system is periodic I don't pretend to understand this stuff, but wouldn't a real mass-spring system slowly stop, due to friction, air resistance, heat dissipation, ...? So a real system wouldn't be periodic.
Earlier quoted context omitted.
What I really like about this explanation is that it highlights the fact that entropy is not a natural property of the physics system: entropy is only defined with respect to some coarse-graining operation applied by an imperfect observer of the system. So as Sabine points out it seems we should really be talking about multiple different entropies, each of which corresponds to a different mechanism for coarse-grainin…
> mass-spring system is periodic I don't pretend to understand this stuff, but wouldn't a real mass-spring system slowly stop, due to friction, air resistance, heat dissipation, ...? So a real system wouldn't be periodic.
Earlier quoted context omitted.
Not really - look up “heat death” of the universe.
The "heat death" of the universe is a concept that deserves to die. The second principle of thermodynamics is true only if you ignore gravity. In the presence of gravity, systems tend to go towards lower entropy, just see how a planetary system can form out of a gas cloud.
Earlier quoted context omitted.
He seems to exaggerate the importance of things when they make for a good story and sound interesting. This is a classic flaw in popular science but I think he's got a lot more egregious with it over the years. The worst example I remember, which is actually what drove me to unsubscribe, was when he said that the golden ratio was "a pretty five-y number" because it can be written as 0.5 + 0.5 * (5^0.5). Anyone with a…
> Anyone with a good mathematical background could tell you there's nothing five-y about 0.5 at all. Um, I disagree? Visually, the 5 is memorable here. "Fivey" just seems to mean "lots of the number 5"?
The part that was new to me was the bit about how a space full of life tends toward more entropy faster than the same amount of space without life. Like the best ideas, it’s simple and makes sense if you think about it, but it’s still a really interesting framing that the complex machinery of life is really just the most efficient “entropy converter”. If there’s something about the arrow of time that speeds towards t…
Right? I think this could be a really interesting basis for a sci-fi novel - the first space-faring civilization in the entire universe trying to force every form of life to keep "entropy usage" to a minimum, so they can prolong their own life span.
Entropy only made sense when I learned it from the perspective of statistical thermodynamics. It's a very programmerly understanding, IMHO, and it's quite intuitive. EXCEPT that the language used is ridiculous: grand canonical ensemble indeed! Anyway, the idea that a system can be in some number of specific states, and that equilibrium is that unique situation where the number of possible specific states is at its ma…
You are given insulated cylinder with a barrier in the middle. Left side of the cylinder filled with ideal gas A, and the right side filled with gas B. If given a particle one can distinguish A from B. The pressure and temperature on both sides are the same. Then you remove the barrier and gases mix. Question: how much work you need to do to revert the system into the original state? Hint: the work is equal to entropy difference between two states.
More generally, if you have proper insulated system and leave it be for a while. All of sudden you will have to do some work to come back to the original state despite energy conservation law holds.
I think the concept would be easier for me to understand if we talked about the inverse of entropy - i.e. some kind of measurement for the concentration of useful energy or "order". I think it would then be more intuitive to say that this measurement always decreases. Do we even have a word for the opposite of entropy?
I think the concept would be easier for me to understand if we talked about the inverse of entropy - i.e. some kind of measurement for the concentration of useful energy or "order". I think it would then be more intuitive to say that this measurement always decreases. Do we even have a word for the opposite of entropy?