exchemist

Sure. What is your problem?

I'm not sure why you think it is saying it takes more energy when done in finite steps. I don't think the text is saying that. What is giving you that impression? This whole business about finite steps is because when you compress the gas in the cylinder, the pressure goes up. It is to show you that you can't just multiply the pressure at the start by the volume change, or you will get the wrong answer for the work done (too low). The pressure is a function of volume, i.e. p is p(V). So as I said before you need to calculate this as an integral: W = - ∫p(V) dV. If you have studied calculus, you will know that integration is the limiting case of adding up a number of steps, each with a different value of the quantity. (Again as I said previously, I personally think it is mistake on the part of the writer of this text to try to teach integral calculus as a sidebar to a discussion of the gas laws. It's just confusing - and, lo and behold, you have got confused! Some simple calculus is something you need to know to do physics at this level anyway.) But luckily for us chemists, a lot of the time we only need to consider PV work in the context of lab experiments done under ambient atmospheric pressure. Under these conditions the volume changes during a chemical reaction occur under constant pressure, so we can calculate PV work, e.g. to work out enthalpy changes, just on the basis of volume change, without needing to do an integration, i.e. we can say ΔH = ΔU + PΔV. (That would not be true if we were reacting gases, in a vacuum line or something.)

It's not to do with the speed at which heat is supplied though. There is no time dependence in dQ(rev)/T= dS. So I would say it is closer to 1 than 2. Transferring heat at a lower temperature results in it being distributed in more different ways within the substance.

Ah, thanks, so this is the Indian government school material that goes up to class 12 in the final year of secondary education. So you are in your penultimate year of secondary school then. That is useful background to your series of questions.

What book are you using?

The law of the bleedin’ obvious?

What book is this?

This needs care. What are you quoting from?

Re (2), yes. As was explained on one of your previous threads, the convention is that energy lost from the system is -ve and energy added to it is +ve. So an exothermic process will have a -ve enthalpy change (ΔH<0). In this case the more you dilute HCL the more energy is released (it gets warm), so the change is -ve. Yr (1) involves calculating the difference between 2 -ve quantities, that's all. Don't get bamboozled by all the -ve signs.

But that's not what I wrote. What I wrote was that the Big Bang theory "depends on" GR. Which it does. Nobody would disagree with you that observed reality trumps any theory. That's obvious. But relativity, both special and general, fits observation, so it is congruent with reality as far as we can tell at the moment. In SR, foreshortening in one frame of reference corresponds to time dilation in the other (I always like the cosmic ray induced muon example to picture this). No "mutilation" of anything is required: it all fits nicely.

I'm the same age as you, then.😊 I think you are rather overdoing things if you think the absence of a preferred frame of reference is somehow an argument against God. Don't forget the Big Bang theory, which depends on general relativity, was originally proposed by a Catholic priest, Mgr. Lemaître: https://en.wikipedia.org/wiki/Georges_Lemaître As for predictions that cannot be tested, the point surely is that for a theory to be scientific it must make testable predictions. General Relativity obviously does this. Even our GPS systems wouldn't work without GR. However, I don't think that means that every prediction or speculative extrapolation that one can make from it necessary has to be testable. As for Einstein's "spooky action at a distance", my understanding is this was one of Einstein's rare errors in that in modern physics there is no such thing. Quantum entanglement does not imply any instantaneous communication between the correlated entities.

OK, evidently there haas been some correspondence about lightning and Einstein outside the thread, that I was not party to. I'll leave to the others who seem to understand what you are referring to.

This is all over the place. There is no "parallel cause and effect". As already stated by @MigL it is a principle of relativity that information, however transmitted, cannot be sent faster than c. So this idea of yours is wrong, at least wrong as far as modern physics is concerned, so wrong to the best of our knowledge. By the way a "pneumatic type" transmission mechanism take time to react, as pressure in a gas takes time to build up and a fast change in pressure at one end of a pneumatic tube will produce a pressure wave that will travel down the tube at quite a modest speed. You then glitch and start burbling about lightning strikes on trains and Einstein. What is all that about?

Yes that is excellent, except for the implicit misogyny. Sessile females etc.

I’m not sure what point you are making here. Are you saying we should not indulge our imagination? Or is it just that we should not present the fruits of our imagination as settled science, perhaps?

I expect there are stats on numbers and violence of hurricanes, floods and wildfires. Also household insurance payouts for natural disasters. I don't have them to hand but maybe you could look up a few of those. I do know, from reading the Financial Times, that insurance companies are very concerned about climate change.

I recall from skiing one distinguishes between une télécabine (cable car), une télésiege (chairlift) and une tire-fesse (button lift) a.k.a téléski. Funiculaire was something else, on rails. One of my brothers went up a funicular railway in Rio which was steep enough to be rather frightening, so he dubbed it a "testicular railway", as you needed balls to get on it.

Yes I can understand the text. I can also discern its implication. Your argument here reminds me a bit of Dawkins's quip: "Show me a cultural relativist at 30,000ft and I'll show you a hypocrite." While you are not espousing cultural relativism, you are in effect claiming there is no such thing as a reliable body of human knowledge, only an individual's own direct experience. That is a (rather destructive) form of nihilism. It is also simply untenable, for the reasons @swansont has explained. Science has a methodology, by design, that accepts knowledge verified by more than one human being. We thus rely on one another's experiences and build models based on a consensus of what those experiences seem to be telling us. This is what makes science reliable - reliable enough for us to fly at 30,000ft, for instance. Something similar, though not assessed so formally, is also what makes certain sources of information credible, i.e. they have been found to be so by many human beings, over a period of time. That is why on forums like these we often ask for sources to back up claims, so that we can judge the claims based on the quality of the sources. Whereas, as we know, LLMs disturbingly often make shit up or rely on bad sources.

Absurd. Suggest you look up what reproducible observation means.

You can have antipopes though.

Hard to envisage, I think, like asking if there is anti-space. What would that look like? Matter and antimatter are entities, whereas space and time are just dimensions. So not really comparable. You can speak of going forward or backward in either space or time. But anti? What could that mean? But maybe a physicist can add more.

"A New Paradigm: Framework for Quantum Testicular Extension". How long before the first paper pitches up on this forum?

….if your balls are spread out across the universe….

Perhaps you have to work out that noble price means Nobel Prize? 🤪

As it explains (admittedly a bit confusingly badly😀), the convention is for work done on the system, i.e. when the system gains energy, to be +ve. Conversely, work done by the system, losing energy , is -ve. In this case the volume decreases, pushing the piston in. So ΔV is -ve. pΔV is therefore also -ve. But we need to express the work as +ve, in line with the convention. So we need to say that W = - pΔV. Here is a better explanation, again from the Libretext source: https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Physical_Chemistry_(LibreTexts)/19%3A_The_First_Law_of_Thermodynamics/19.02%3A_Pressure-Volume_Work This uses an integral which is better since, as V decreases, p will generally not stay constant but will increase. That means p is a function of V, so you actually need to integrate PdV with respect to V. What your text is trying to express, not very well, is the principle of integration as the limit of a sum of lots of little steps, each with a slightly bigger p than the one before. (Personally I think it's a lousy idea to try to teach the mathematical principle of integration as a sidebar to a discussion on the gas laws. In my view integration should be taught on its own, as a piece of the mathematical toolkit you need to do this kind of science. It's just confusing to cover it here.) You never answered my previous question about what text you are quoting from. Can you reply, please?