joigus

The periodic table of encyclopedia entries? Again??

Agreed. I think the reasons having to do with PEP and conservation laws were very robust already. I sometimes succumb to the drive to try to help the idea as much as I can before it dies. I suppose it's because after a while I get too tired of always being quickly dismissive. I sometimes want to make a point that it's not that you have an extreme dislike for the idea. Gravitation is indeed the only interaction that could have neutrinos clustering at some level in some scenario. If you had a universe with no dark matter, no scatterers of any kind, nothing, huge distances before you could find the next galactic halo, I guess at some point neutrinos would start to cluster in huge mega-halos gravitationally... Anyway. As you said, it would fail on so many levels.

Well, they can cluster gravitationally, therefore very weakly. At galactic scale. x-posted with mordred. Plus all the other reasons they're telling you...

Neutrinos cannot cluster. They hardly interact at all.

Wrong. Beta decay must be involved, as said. And, There's a cute explanation in Surely you're joking Mr Feynman, about his father asking him, "when an electron falls from a higher to a lower orbit, where was the photon before it happened?"

Close enough. that no integers a, b, c > 0 could possibly satisfy the equation an+bn=cn for n also integer and greater than 2. Otherwise there trivially are such a's b's and c's aplenty.* I know of no practical applications of it. But I wouldn't rule them out. * Counterexample: n=3, a=2, b=1, c=91/3

Depends. Some time I could do without. Time has a filling, and that's what's of the essence.

You read my mind. I'm not one of those people who can dash off a quick essay over the cellular. I remember having thought of "wannabe philosopher". Quotation marks would have done the job. And your expression certainly does it. The truth is we get a lot of this. People who think they can do philosophy, and by means of their philosophy of sorts, clinch the case of the most difficult (and long-standing) scientific problems: What is time? Did the universe have a beginning?, etc. The truth being they don't even get started doing science. They do very poor philosophy too.

I meant 'another "philosopher"'... Sorry, I'm on my mobile phone and typing is harder.

It probably has to do with a forward-scattering amplitude. Thereby the pi.

Another philosopher venturing into the deepest scientific caves without the lantern of maths...

Mass really is rest energy. That's all it is. You have to think of mass as some kind of cohesion energy. Mass is the energy that a piece of matter still has even if you take it to a standstill. (To understand this you need Einstein's theory of special relativity). A world with no mass is conceivable. It would look the same at every length scale. A world with no energy is nearly unconceivable, OTOH. I agree with @Mordred that those are not necessarily bad questions. They're good --if hard-- questions. Mixing --that Mordred mentioned-- further complicates things: Particles with well defined mass don't have other quantum numbers that well defined. They are quantum superpositions of states with different quantum numbers (analogues of electric charge). Some particles are so-and-so percent of this particle and so-and-so percent of that other particle. And this "mixing angles" (that determine how much of this and how much of that there is) are fixed that way since the beginning[?] of the universe... It's very confusing. My advice would be: Don't think about mixing for the time being. In QFT, mass is a mess. In Newton's mechanics, it's simple because it's a primitive concept and doesn't have to be justified. (Sorry I wrote "sofisticated" instead of "sophisticated". I'm bilingual, and I get the spelling of Latin/Greek-root words wrong when I'm writing in a hurry.)

Why? A world made of photons would gravitate. It's energy that's the source of gravitation, not mass. All fields are quantum fields. They should be. It's just that people haven't been able to make sense of quantum gravitational fields so far.

No problem. You must think of quantum fields as things of which it makes sense to think of them as "being there" but in a vacant state. The field people usually refer to is the vacuum of the Higgs field. One has to spend considerable amount of energy (and money) to take it to an excited state with occupation number = 1.

It's not either/or. Quarks cannot exist as individual massive particles, and protons aren't the smallest hadrons (strong interactive particles). Mesons are short-lived but real enough, and are composites of quark-antiquark. And they are smaller than protons. The so-called Higgs multiplet is actually a quantum field with 4 degrees of freedom. 3 of them are called Goldstone bosons and they're the ones that massless particles swallow up in order to acquire mass. The left over degree of freedom is what we call the Higgs boson. So trying to picture what happens in terms of an actual "swarm of Higgs particles" flying around is the wrong way to picture it. This leftover DOF of the Higgs multiplet is normally unoccupied. Occupation number = 0, in the QFT parlance. So it's not really there. You have to actually provide a lot of energy to make it show up. The swallowed up DOFs are what's dragging the massless particles to make them look as they've got mass. I don't know whether that answers your question, if only to clarify that the actual picture is a bit more sofisticated than particles modifying other particle's trajectories. Did that help at all? It's all energy that's the source of gravity, not only mass, and certainly not just the Higgs field.

Vagueness cannot be proven false, but that is no virtue. Try to contradict this: "There is something about something that could explain something in some cases." It's falsifiable ideas that get the ball rolling. There are other things: Explanatory power, prediction, economy of ideas, etc.

Niels Bohr said it. But he didn't say QM is absurd. To say that QM is extremeley counter-intuitive is one thing. Quite a very different thing is to say that it is absurd. No physicist would say such a silly thing. The quote is frequently phrased as, After a few weeks you're over it, as you should if you want to do physics and complete the exercises. An uneasiness can stay with you for a while, but then you finally accept it. Why wouldn't you? It's the way things behave. Conservation of energy is a local conservation principle, within the allowance of Heisenberg's uncertainty principle, even in QM. So we know this not to be true. It is well known that QM introduces a tension between reality (the possibility that the output of an experiment can be predicted with certainty for certain groupings of observables) and locality (the fact that information, energy, angular momentum, and every other conserved quantity must propagate through space, and cannot disappear here and appear there, so to speak). If you want to introduce a model that proposes non-local propagation of the amplitudes, it would be strange, but I don't think it could be ruled out based of first principles. But you've done nothing of the kind. You haven't introduced any hypothesis. You just have a vague idea: Something non-local happens that somehow explains something in some cases. Not the most promising of starts.

This is not a conceptual problem for quantum mechanics. Then you just dissolve into vagueness: "it would be like", "a certain behavior", "would be like" three or four more times, "more or less energy" etc. Too vague to even make sense. And no, particles cannot exceed the speed of light, not even "in some cases." So-called virtual particles --if that's what you're refering to--, are not actual particles, they are modes of the quantum field that cannot be measured but must be included in the calculations.

It would be, not only presumptuous, but plain stupid for me to disagree with you. I'm keenly aware of this, yes. And I was for a while thinking about making due qualifications --retroviruses, that you mention, for which RNA goes to DNA, and prions, which I implied without mentioning them, and have to do more with folding or packaging of proteins of "chaperoning" as I understand. That's why I chose the prions as an (admittedly extreme) example of how the doings of the proteins more heavily determine what the brain ultimately looks like, does or doesn't do than the other way around. I introduced that example precisely because the OP was about the brain in particular. Francis Crick famously regretted having called this DNA-to-RNA-to-protein predominant flow of information a "dogma". Dogma is something accepted without question, while paradigm is just a typical example of a pattern. It is unfortunate that so many people use the word "paradigm" more pompously than it deserves, IMO. A paradigm is just a typical example of something. But you're totally right, of course. It's more complicated that that, with lots of feedback going on from the organ level to the molecular level, and back.

I was thinking the same thing: WTH are Calabi-Yau manifolds doing here? A picture is a picture is a picture...

You've had excellent responses already. You seem to be looking for a video though. Here's one just as a sample: Of course, as they've told you, it's not about the brain monitoring the process, but about regulatory sequences being activated/silenced, etc depending on the signaling going on. In order to understand all of this, you need to have a grasp of the paradigm of molecular biology: replication --> transcription --> translation from DNA to protein, which is almost always the case in bio. As an extreme case of the complete opposite happening (proteins acquired somewhere else determining the brain's behaviour), bad protein packaging can give you a brain going horribly wrong. Those are called spongiform encephalopathies.

Obviously. grav force/strong force is a dimensionless number, and represents a natural scale in Nature. Newtons OTOH are just some convenient units useful on the Earth for weighing bricks and such. My own favourite unit of force is the Jocular, and one Jocular is equal to 1020 N. Your coincidence has just vanished when expressed in Joculars. I concur with the other objections expressed, btw.

Good tip too. Thanks for the recommendations and welcome back.

Sorry you see it as though I wasn't trying to help. I was. I thought it was more urgent that you learn to handle dimensions than it was for you to handle vector addition. As an old professor of mine said, 'If you want to be able to write Chinese poetry, your first goal should be to be able to write Chinese'. I wish you best of luck with your Chinese poetry.

You said, This is not dimensionally consistent. All physical equalities must be dimensionally consistent. It can happen though that when a dimensional quantity is a universal constant, you can choose it to be one, and there is a dimensional reduction. AFAIK, the centimeter is not a universal constant.