joigus

Slow neutron experiments are not high-energy experiments. Google for fission and slow neutrons. Many other experiments aren't.

Exactly. Let me mention some lower-level authors for you: Dirac, Pauli, Einstein, Fermi, Bohr, Schrödinger, Feynman, Schwinger, Yukawa, Yang, Parisi, Altarelli, Aspect, Zeilinger... Every major physicist of the 20th/21st century except Prigogine, maybe. There are no unanswered questions about special relativity. None. When you start learning about relativity it's well worth spending some hours thinking about Alice and Bob experiments. All of the A/B thought-experiment paradoxes in SR have been solved. But if you know anything else about physics, you start seeing many paradoxes and peculiarities get resolved and you get motivated to learn it and think in relativistic terms simply because it makes huge progress everywhere in physics. Not least because it predicts antiparticles, getting energy from mass, it gives you the right properties of helicity and chirality of elementary particles, it explains the observed speed-dependent lifetimes for elementary particles. It is also an inescapable consequence of Maxwell's equations. It gives you a consistent picture of elementary processes (congruences of events, instead of the same thing (eg. a collision) happening at two different coordinate times). If you saw a particle-antiparticle annihilation coming at you at different speeds, you would perceive charge not to be conserved, because one would disappear before the other did. My suggestion: Try to learn some electromagnetism and you'll see how special relativity is necessary. The right expression for the energy of the electromagnetic field ~E2+B2 is a direct consequence of relativistic formulation, and it has the transformations properties of an energy under Lorentz transformations. The right expression for the Lagrangian of the EM field ~E²-B² is a Lorentz-relativistic invariant, not a Galilean invariant. Galilean invariance leaves magnetism unexplained. It also explains why charge is a relativistic invariant and the conservation of charge being agreed upon by all inertial observers, as I said. It's not difficult to come up with tens more examples. It is watertight. It contradicts your intuitions, it contradicts direct human intuitions, I know, most of us here know. But then, these intuitions are wrong. Many people have tried to bring to your attention the Alice/Bob approach; others have tried a more formalism-related approach; others, experiments with muons, etc... Your arguments remind me a lot of "arguments" against evolution on the grounds that we don't see anything intermediate between a whale and a dog, dismissing the wealth of evidence as if it were irrelevant.

Are you implying that the contents of all your thoughts are this seven liner? Please tell me that's not true. As someone self-declared to belong to the military, do the words "slow neutrons" ring a bell to you?

You mean (gamma)-1x' and (gamma)-1t'. I may have swapped left and right. Equations are insensitive to swapping left and right. A=B is the same equation as B=A. All the operations I told you already: Couldn't you reproduce the partial steps up to, \[x=\frac{\sqrt{1-v^{2}/c^{2}}}{1-v^{2}/c^{2}}\left(vt'+x'\right)\] ?

What question? Oh, I see. Bob would be the primed system. Alice would be the un-primed system. So to see how Alice sees Bob, you must substitute x'=0 in the un-primed coordinates as a function of the primed ones. x_A, t_A correspond to x, t x_B, t_B correspond to x', t' You have your notations mixed. So you express x, t (x_A, t_A) as a function of x', t' (x_B, t_B) and substitute x=0 (x_B = 0) with v/c = 0.4 Does that help?

Arbitrary.

Always break down problems into easy steps. Try a numerical example with say 3, -2, 7,... Get the idea. And then do it with a, b, c,... Then go for powerful and general methods. Once you get a solution, don't just be satisfied. Think: Does it make sense? If I make v=c, what do I get? What if I make v=0? How does the equation of a light ray x=ct or x=-ct transform? Check.

Bagpipe players in the subway have always bothered me. But bagpipe players in the subway doing a headstand are even worse.

OK. Let me know if you can follow the steps up to here: \[v\left(t-vx/c^{2}\right)+x-vt=v\sqrt{1-v^{2}/c^{2}}t'+\sqrt{1-v^{2}/c^{2}}x'\] \[\left(1-v^{2}/c^{2}\right)x=\sqrt{1-v^{2}/c^{2}}\left(vt'+x'\right)\] \[x=\frac{\sqrt{1-v^{2}/c^{2}}}{1-v^{2}/c^{2}}\left(vt'+x'\right)\] OK? If you have any difficulty with that, tell me. There's one minor step left. And then the other equation. But if you understand this one, it's almost done. You can PM me, if you want.

I think we can call it a day. Everybody get ready for drumbo's next thread: "Fat people should not be allowed in public transport."

Pascal must have been under a lot of pressure when he said that. I see no way in which this could be false.

Good point. That's called the curse of knowledge. It doesn't happen only to scientists, though. There's also the curse of expertise.

Inferring correlations when you see guys in the subway is no robust way to make serious statistics. It is well known that humans tend to apply filters and bias the results when they read too much into their everyday observations. For example, when people notice some guy who's dressing in a way they already disapprove, they tend to pay more attention when he's also acting in a way they disapprove. So you must be careful with such observations.

Mmmm. Maybe that's because when someone is mature enough to watch or read news reports, it's already too late. Same reason why it's inconceivable that a person who studies science should not know who Shakespeare or Van Gogh were or what they did, it is inconceivable to me that a person well learned in the humanities should not know in simple terms why we know the Earth is billions of years old, or animals and plants evolve, or everything falls with the same acceleration in a vacuum. Those ideas can be explained without mathematics, or very technical vocabulary or complicated reasoning. I think it is incumbent upon everybody involved in science education to devise ways of teaching science that are suitable to the non-scientific mind, that can be easily assimilated by everybody, and make a permanent part of a person's education, irrespective of what they do. Some politicians, ie., don't seem to understand that long-term (climate) change is far more predictable than tomorrow's weather for very good reasons (one is concerned with averages over centuries and continents; the other with right then and there). Anybody can understand that if properly explained. These people suffered a deep alienation from science very early in their lives, and I would like to know why and what can be done to put an end to this tragic scientific illiteracy. I've been arguing for years about the necessity that journalism becomes a speciality of every technical branch of knowledge. Such specialists should be trained in making the messages from science percolate from specialists to general public. Techniques of general journalism are simply not good enough. The Donald Trumps and Michael Caputos of this world don't come from a parallel dimension. They've been raised here. I understand there's always going to be die-hards. Denial is a part of human nature. But politicians should be better than that. Better education can limit the damage.

Here's the cartoon, by the way: Before anybody says anything, I've got several issues with the cartoon. I'm concerned with the "kernel of truth" part of it, that's all. I tend to see it more about heterogeneous demographics, rather than ups and downs or one-night stands. But I wouldn't know. I'm not an American. You must have a reason to say that.

Nice topic. Before kissing, go lick some steel.

And try gracing the dinner table with a conversation about feldspar. You'd be shown the way out before the dessert.

I must say this comment is making me think a lot. Political movements don't just pop up by spontaneous generation. They capitalize on some previous climate of opinion, discontent, etc. For some reason a fundamental disconnect between science and some sectors of the general public has grown, and I would like to understand the roots of that. Maybe such a connection didn't exist in the first place, and people who are trying to turn to science in search of answers are easily disappointed, maybe because of the very simple fact that opinion is not enough, and they don't expect that. I saw a cartoon the other day suggesting that it's to do with science and scientists sounding arrogant in the ears of big swathes of the public. I'm not so sure about that, but there seems to be a communication gap. Creepy!

Which GOD?: Good Old Days? Great Ominous Darkness? I'm not familiar with the acronym. -------------------------------- And do you mean the kind of discipline and compassion that you've displayed in abundance here?

The Trump Administration seems to be getting quite explicit lately about something that's been in the air for quite a while. The man himself and some of his officials seem to be taking the anti-scientific discourse up a notch. Very worrying news coming from the US these days. I thought I'd never see the day: https://edition.cnn.com/2020/09/14/opinions/another-day-another-trump-outrage-on-climate-and-science-oreskes/index.html?fbclid=IwAR38oXn2xJLdp5rjnPZHeAsQtNSkkptKuZy_C3Sd3LJ5c2Usyv08TAzySQ8 https://www.nytimes.com/2020/09/14/us/politics/trump-biden-climate-change-fires.html?action=click&module=Spotlight&pgtype=Homepage&fbclid=IwAR38oXn2xJLdp5rjnPZHeAsQtNSkkptKuZy_C3Sd3LJ5c2Usyv08TAzySQ8 https://www.nytimes.com/2020/09/14/us/politics/caputo-virus.html What are your thoughts?

I generally agree. This is a very hype-sensitive topic.

The only case that I know of anything in the way of a civilization appearing as a direct consequence of the Younger Dryas is the Natufian culture. The Natufians were hunter-gatherers, but kept dogs and made sickles with which to harvest wild grain. They seasonally settled places were they kept some of their heavier proto-agricultural hardware --huge pestles and mortars-- and made repairs on their seasonal homes. When the glaciation hit hard, they seem to have settled permanently near the water and brought stores of grain with them. It is known that when people settles society becomes hierarchical. Some chieftains may even develop a funny orange toupee-like hairstyle. Everything that we associate to the word "civilization" (monumental architecture, overlordship) I think came a bit later. Although an interesting precursor of civilization that seems to overlap with the Younger Dryas is Gobekli Tepe. Interesting: monumental architecture from a hunter-gatherer society. I wasn't aware of the impact theory, although I tend to think that there is always a temptation to find one cause for changes that probably are more complex. I have never considered the possibility that Elvis was a Natufian or that the Natufians assassinated JFK. 🤣 This is a very interesting topic.

Thanks @Area54 and @MigL. Do you know of any geological/atmospheric process that could replenish PH3? Apparently the authors have tried some of that and ruled it out. Also, does anybody know the answer to, ?

Dark matter gravitates; dark energy anti-gravitates. Scales are hugely different too. Dark matter's attraction is very noticeable at the range of galactic haloes. Dark energy's repulsion is noticeable only at scales much bigger. So I can't see how they could "be one." The rest doesn't really amount to a scientific proposal. Mass is known to have to do with chirality and helicity, for example, and you haven't adressed that.

Question for the chemistry experts: Suppose that were phosphine they're measuring in Venus' atmosphere, and never mind where it comes from. Would it be possible for this chemical to last in those conditions for, say, billions of years after it was produced, whether biologically or otherwise? OK. I'm no expert in chemistry, but I'm kind of an expert in explanations. And that is not one.