joigus

You of all people are most welcome. The situation with mass in the standard model is potentially a bit confusing, at least to me. Well defined mass states are made up of superpositions of flavours, a phenomenon we call mixing*. The fixed-mass states --eigenstates of the mass operator in QFT parlance-- are the physical states, while superpositions of different flavours get physically connected --can evolve into each other-- by means of these mixing angles, contributing to the observed mass by means of perturbative quantum corrections. OTOH, people do talk about "Majorana mass" vs "Dirac mass." Example: https://physics.stackexchange.com/questions/101371/majorana-mass-vs-dirac-mass Not very proper terminology --mass is mass indeed--, but just saying. Neutrinos are anything but trivial. QFT itself is anything but trivial. And neutrinos seem to be on a mission to make the world look as skewed as they can. ------------------------------- * https://en.wikipedia.org/wiki/Pontecorvo–Maki–Nakagawa–Sakata_matrix https://en.wikipedia.org/wiki/Cabibbo–Kobayashi–Maskawa_matrix https://en.wikipedia.org/wiki/Weinberg_angle

LOL

As repeatedly noted above, there isn't such a thing as 'three different types of mass.' You could speak, in some sense --and some people do-- about two types of mass: Majorana mass, and Dirac mass. But those are not different types. It's really about how the mass term --the only type of mass we all know and love-- connects the left-handed component to the right-handed component in the Dirac equation. But it's the same kind of mass in terms of inertia. 1, 2, and 3 refers indeed to three distinct values of mass. It's really the three kinds of so-called flavours that the theory doesn't predict. IOW: Why are there three families of particles? Ie: three versions of every other particle that there is in the universe, with every other parameter exactly the same, except for mass, which differs from one family to another.

Ah, it does ring a bell now that you mention it. I must have mixed them, as in Spanish it's rather "an elephant in a pottery shop," (un elefante en una cacharrería), which I seem to have adapted to some kind of hybrid form. Live and learn! Duly noted. The list of things you don't like is growing thick. I was benevolent, I'd say. You juxtaposed the words "more or less entirely" which is a notorious oxymoron that didn't escape my attention. But I'll stay tuned for further nuances on when something is "more or less entirely" this or that. Pointing at straw-clutching is not the same as doing as strawman. That's your call, not mine. But I'll refer to my previous comment on 'kid gloves.' I'll try not to correct you anymore. Let other people do that thankless job, because, (My emphasis.) God forbid! You read too much into what people say. You think I'm upset... You clearly don't know me at all. It's anecdotal, but it tells quite a bit about the problems you seem to be having with some people. No 'hello' or 'cheers' or 'how are you?' or 'see you around''... Just a blunt 'blah' coming from a lurking presence in the darkness. "Consciousness" It took me a couple of seconds to realise it wasn't some kind of threatening / cryptic message from out of the woodwork. Nice.

I have to make some qualitications to what I said about ideal gases not having internal degrees of freedom --energy has nowhere to go... That's not true. They have. But only complication is Cv, Cp (specific heat) which just sets the scale for the relation entropy/temperature I was talking about. No time now. Sorry

Here: And then --not 'than', nor 'that' --, Because there's nowhere else for any form of energy to go but the state variables P, V, T. And, interestingly enough an ideal gas provides you with a better gauge for entropy than any other system has. It's, in a manner of speaking, a natural dipstik for entropy. It provides you with the zero and with the slope entropy/temperature. The exception to this is, as we well know, 1) Phase transitions: As the temperature goes down, the ideal gas (P, V, T) temperature must be replaced by another relation that contemplates the finite size of the molecules and their mutual short-range repulsive/long-range attractive force --Van Der Walls gas. And, 2) Quantum mechanics has to replace classical Newtonian mechanics when we get close to absolute zero of temperature. But point 2) should be of no concern to you. Point 1) should.

It's more kind of like a fencing trick than an insult, which is what you seem to be suggesting. Arguing is a little bit like fencing. It's certainly not a strawman. When a person takes something for granted, as if the previous statement had been totally absurd... and then you go, "obviously you're right... No, hang on." And you deploy your next argument. It's for greater effect in the arguing, not to insult you. I suggest you do the same: Be a good sport, fence back, smile, shake hands whether you "win" or "lose" --or think either you or your contestant have learnt anything from each other-- and you will make friends here. And what's more important, you will sharpen your own views, analytical tools, etc. I've been wrong quite a number of times on these forums. I've always tried to be grateful, on some occasions by PM-ing the person and saying something along the lines of "I hope this message finds you well. Thank you for so elegantly pointing out my mistake." Certainly not by sending a PM with nothing but <correction>blah</end of correction>. Without even a "Hi, pleased to meet you," and "blah" being a mispelled word, which is a false friend in my native language vs English. Sound familiar? I'm sorry. I'll wear my kid gloves next time.

Yes. Thank you. I remember that definitions of efficiency also depend on whether it's an engine, or a refrigerator, --inverse Carnot cycle-- or a heat pump. In the end, it's a definition based on our particular interest.

None, obviously... or do they? https://en.wikipedia.org/wiki/Prenatal_memory There's also such a thing as prenatal/perinatal stress, prenatal/perinatal imprinting, etc. The fact that you can't conjure up the memory doesn't mean it's not there. We're made of atoms. It is to be expected, one would say. And I'm just talking from googlesay...

There is ultimately no such thing as normal, healthy babies, the very same reason why there isn't the right tallness, or why lactase persistence is neither good nor bad. It's an interaction between genes and environment that tells what traits will develop, and which ones are more convenient to our reproductive success, or to our success measured in any other standards. Because many genes have to do with psychological development, I think it stands to reason that personality is not a program written on a blank slate by the environment, as you seem to have suggested. Or perhaps I did misunderstand you, which is entirely possible, in which case I apologise. But my post was more about the manner of your answer really. No offence, but you strike me as kind of thin-skinned. Even though you manage to make brilliant points at the last gasp. Example: Interesting... Care to develop on that one? It is your split thread after all. Oh, I think you lot have many other things. But you are prime curators and antiquarians, so you can be trusted with them.

(I emphasised the spots where you came across as kind of dogmatic in the face of evidence to the contrary.) A child with disfunctional FOXP2 genes won't speak properly no matter how much plasticity you hammer into them. It is widely accepted today --I think-- that human behaviour is a complex result of interaction between genes and environment. So this assumption of yours seems like in tatters, to say the least. I suppose that's what @iNow meant. Or something along those lines. I'm willing to learn more if I'm mistaken. You, as we say in my country, entered the scene like an elephant in a china store. I do appreciate your contributions to the forums --very much--, especially in the area of physics. So, please, take it down a notch and stay calm. We need you in the physics department. Too many loonies out there. We're learning from each other, as @MigL said in quoted thread.

BH falling into object or the other way around is a matter of reference frame. The thing about small Schwarzschild radius --in comparison to falling object-- is a question about tidal forces (gradients of gradients or second-order derivatives.) When object is very close to centre of gravitational attraction, it's no longer possible to consider local inertial system as such, due to second-order effects (second order derivatives.) I'm sure you know about this --from what I can infer. You're either an expert on this or a person so knowledgeable that not even an expert could tell the difference.

As usual, I refer to the question on the title when I can't follow the logic that comes below. Can a material object cross the horizon of the BH? If the Schwarzschild radius of the BH is much bigger than the size of the material object (2 cases, I'm assuming free fall): From the outside to the inside of the horizon: Yes, and if the BH is big enough, the material object would be none the wiser that it's crossing a horizon. From the inside to the outside of the horizon: No, and due to its being in free fall it would be none the wiser that a huge part of space-time is forbidden to them But, If the Schwarzchild radius of the BH is comparable to the size of the falling object: The material object would be squeezed to nuclear spaguetti, according to standard knowledge.

I've just found this, but wouldn't know why that's the case: (My emphasis). From: https://en.wikipedia.org/wiki/C/2022_E3_(ZTF) Maybe you can make something out from this.

So the answer to the question is a resounding yes! Carnot's efficiency formula is valid. There's no reason to believe its validity depends on heat being a fluid or not* --with our modern understanding being it's not, and Carnot's reasoning being the 1st stepping stone towards understanding it must somehow be quantifying elementary dynamical processes, which leads to the concept of entropy. There's no reason to believe the engine eventually grinding to a halt has anything to do with efficiency calculations**. There's no reason to believe the time it takes to complete a cycle --or thousands of them-- has anything to do with efficiency calculations. And finally, there's no reason for me to believe super-busy OP --with 113 comments at the time I'm writing these lines-- will ever even bother to address any of my comments. * If the fluid happened to correspond to a conserved quantity, it wouldn't make much of a difference, TBH. It's a conserved quantity that must go somewhere --for all that Carnot's reasoning is concerned. "Phlogiston" is a place-holder for a concept that was better understood later. ** Mind you, if the engine lost 0.00000000000001 usable energy every cycle, it would eventually grind to a halt anyway. Mind you also, @swansont's observation that, already gives you another clue: Under otherwise fixed conditions, re-scale Tc/Th, and things will get better in terms of efficiency. That's not direct proof, but certainly a good "thermometer" --allow me the conceptual pun-- that Carnot's reasoning is spot on. PD: 1) I said before something to the effect of "entropy leaking out." That wasn't quite right. You see, entropy is not a conserved quantity, so that was, strictly speaking, incorrect. But it can certainly go up and up for the whole universe, and it does reflect a loss in usable energy --something that can be exactly quantified by means of Gibbs or Helmholtz free energy, as the cases may be. And it will, as soon as you deviate in any way from the case of a 1-phase ideal gas ideally separated from the heat reservoir --and thereby exchanging both reversible work and heat-- by means of these "ghostly," non-existent walls that Carnot once imagined. 2) @Tom Booth In every reasoning you've deployed so far, you're counting irreversible work bluntly as "work" in the sense of Carnot. That's a blunder of such proportions that I don't wanna get involved in your reasoning any more. It will only lead to one mistake after another. When irreversible work is done, and you don't do anything to store it in any way in the form of state of the system, IOW, it leaves no record, it's as good as lost. Gone, forever, bye-bye. It's there, but you no longer know where it is. Nothing in the system's state reflects it's been done, or whether it came from work or from heat transfer. So you're tampering with concepts that are ambiguous if you try to interpret them in terms of Carnot's formula, and thereby, reversible thermodynamics.

Perhaps "upper bound" are the words to look for here? It definitely sets a theoretical upper bound in terms of energy obtained to energy invested ratio, having nothing to do with time --how long the machine is running, as you pointed out before--, or with whether the machine will eventually stop or keeps going forever --as Swansont pointed out. Because the Carnot cycle is defined in terms of state variables --due to all intermediate states beeing equilibrium ones-- and because an ideal gas has no internal mechanism to hide energy other that its pressure, volume, and temperature, no matter how many contraptions or intermediate complications we introduce, this upper bound cannot be overcome. The dynamics of this discussion does remind me of that of a Carnot engine, with a reservoir full of an inexhaustible resource, and the corresponding sink that can take any amount of such resource without in any way changing its state.

Those are excellent points that partially overlap with what I was thinking at this point. A Carnot cycle is an extreme idealisation. When I said before it's just based on (1) Conservation of energy (2) Existence, to a good approximation, of heat reservoirs I wasn't quite thorough. You need the gas doing the work to be ideal. You were quite right when you said, If the "working agent" is an ideal gas, and all the intermediate states are of equilibrium, its energy exchanges with the rest of the universe can be expressed as proportional to its temperature. Thereby Carnot's limit as a function of both temperatures. It's not --as OP has been repeatedly suggesting-- because the basic concept of efficiency is based on temperatures. It's not. It's based on energy exchanges. Anything, repeat anything, that deviates from this behaviour, would result in further "leaking out of entropy" to the rest of the universe and will make things worse in terms of efficiency. This is intuitively clear and only properly understood once the concept of entropy is introduced. It would be an interesting exercise --which I'm not going to do-- to replace the gas for a real gas, with an equation of state more similar to Van Der Waals, a virial expansion, etc, to see that things would only be made worse with real gases --never mind mechanical elements that introduce irreversible work and consequently extra dissipation. Another interesting approach would be a treatment based on statistical mechanics, which allows you in principle to make the isotherms not exactly isothermal, and introduce fluctuations in temperature.

Sorry. I was interrupted and then forgot. I agree.

First, we should agree on what the basic "objects" are. Quantum field theory tells us that those are quantum fields. Quantum fields are kind of "instanciation machines" for their quanta. These quanta are discrete jumps in the fields that we recognise in 2 ways: (1) Mathematically: they carry irreducible representations of the Poincaré group (2) Experimentally: They show themselves as discrete excitations on experimental equipment consistent with the values of energy/momentum/angular momentum that the theory implies The second one is more or less clear, I'd say. We never find "half an electron" hitting anywhere. The first one means that these fields factor out in terms that, in turn, cannot be further factored out into parts that mathematically represent translation, rotation, and motion at a speed.

Very good explanations here, so there isn't much of significance that I can add here. Just another rephrasing of the same idea. The whole concept of "touching" rests on the assumption that one thing is "here" and the other thing is "there," and that this assumption can be pushed to any scale we want. Quantum mechanics tells us that's an illusion. All the concepts involved must be reviewed: "Here"/"there", "one thing"/"the other thing", and "being". It's as @Genady says, It's very radical.

Thank you. South Asia is a big puzzle.

(My emphasis.) Advise: Go back to your second incarnation and borrow a page from his book.

Here's the paper with the find that Denisovan ancestry reveals two distinct pulses of Denisovan genes: https://pubmed.ncbi.nlm.nih.gov/29551270/ And here's a paper based on applying Bayesian methods with a bundle of plausible models as contrasting hypotheses, and finding that there seems to be support for a "third" --meaning distinct, but genetically equidistant between Neanderthals and Denisovans-- group of humans: https://www.nature.com/articles/s41467-018-08089-7 I learnt about these papers in this wonderful podcast by Stefan Milosavljevich: I always think twice before recommending a YT channel. This one is prime quality. Número uno...

-giggle Sorry, I should've said "a fourth group of humans". Or fifth, or even sixth... Let's just say one more. We do have pretty good physical evidence of ourselves.

That's quite correct from what I remember too from the mid-'10s. But we must stay tuned, because "Denisovan studies" is a very active field lately. I've recently read that experts are finding traces of Denisovan traits in native Americans. The study is based on protein analysis, rather than DNA. It has to do with the structure of the lips. https://www.sci.news/genetics/native-americans-lip-shape-gene-denisovans-09330.html I've also learnt that a third group of humans approximately contemporaneous of Neandertals and Denisovans is being guessed at based on statistical analysis. I'm trying to get more info on that.