joigus

AFAIK, the problem about trans fats --for humans in particular-- is their high melting point. Because they --as John said-- have double bonds in the middle of the chain, they allow for hydrogen atoms to be either both on the same side (cis) or on opposite sides (trans), so that trans give rise to molecules that tend not to coil or bend so much. This results in straight chains that function pretty much as saturated fats when it comes to melting points. Molecules that tend to coil act more "pointlike" than molecules that remain "straightened up", which is what qualitatively explains the difference in melting points. So they tend to clog more easily in your blood. I'm not aware of metabolism having to do with other negative effects, but it could be.

That's not exactly what seems to have happened. Einstein came up with a cosmological constant in order to account for a static universe, which was his, shall we call it, theoretical prejudice. Einstein's field equations do allow for a term which is proportional to the metric tensor, which has so-called covariant derivative (identically) equal to zero. So Einstein realised that adding such a term did not change the auxiliary condition that was the main drive for his conjecture. Namely: A gravitational tensor which had identically vanishing covariant derivative. Einstein knew the right-hand side of his equation had to be conserved, so he guess a left-hand side that was identically conserved so that his equations were some kind of curved-space analogue of Maxwell's equations. was identically conserved --had identically zero covariant derivative. Having identically zero covariant derivative are technical words for expressing a local conservation law in a curved space-time (what disappears inside a volume must do it by crossing its surface.) You can always add this term without changing this property. The problem with Einstein's solution was that it produced an unstable solution, so it didn't make much sense. But also, had he guessed that introducing a positive cosmological constant would require an expanding universe, he would have anticipated an experimental discovery that only came decades later by Penzias and Wilson. He regretted that predicting an expanding universe had been within his reach but he fell short because of this theoretical prejudice that the universe must be static. That's more or less the story. Maybe I can provide some better explanation or bibliography later. Or other users can further clarify.

You're right. I was in doubt about that too. Maybe a ferromagnetic salt could play the role of the "iron particles"? You could package permanent magnetic dipoles, while having the particles be soluble in water... Just a thought. https://en.wikipedia.org/wiki/Ferrofluid Edit: Ferromagnetic salt is probably not the proper term. Paramagnetic salt is more like it. This checks with what I was thinking, although you know much more than I do about this. My impression was that it wouldn't release/absorb much heat.

It's a beautiful experiment, and it seems to me that it's quite doable. But keep in mind that, as long as your jar is not a closed system, it doesn't have to display entropy increase. Same reason why the gas in a refrigerator can be made to cool by expanding adiabatically --not getting or giving heat from/to the outside--, but exchanging work. In this way, the universe as a whole would see its entropy increase, but parts of it --the jar's interior-- would see their entropy decrease. Why don't you try it? Some people here could give you advice. A Dewar flask, a magnet, and a thermometer could do the trick.

Very interesting. The gif didn't work for me. I've found it here, and you can really see the vortices pushing against each other: https://phys.org/news/2021-01-reveals-jellyfish-virtual-wall.html

The book itself in an excellent example of gravity too --6 pounder.

Absolutely. I don't disagree with @HallsofIvy about the specific point. What I meant, of course, was in the context of the general flow of information, which was exclusively unidirectional. I'm seasoned enough not to recognize the pattern of someone being disingenuous on purpose, just for laughs. Making fun of people whom, deep inside, you feel to be more intellectually capable than yourself, and relishing in the cheap thrill you get from pulling it off: "Look at them, they think they're so clever, and they can't tell I'm just having some fun at their expense."

I gave them the benefit of the doubt for a while, way past the reasonable... Just in case. But no. They opened another thread, and then another, and another, without ever addressing anything they were told, not even the slightest trace of a reasonable followup question. Only more questions to new, equally silly, unrelated "problems." The last thread's title was "What's 2+6?", and they said "I'm totally confused," which was the opening statement. Really? Language barrier? I don't think so. Now, you don't have to read between the lines to know this person was pissing on all of us. Good riddance, that's all I can say. I've seen that pattern before and I have my ideas about what can lead a person to act in that sorrily pathetic way, but I would be off base speculating about that here. Then there are people working on social experiments out there. I just know, because I happen to know one scientist who works on that, so... You never know.

The way I understand the comment, it may be any other subject.

It was the "unmanifest" bit, wasn't it? Maybe they mean non-observable?

In order to have an electric field you always need a potential difference. In fact, you can have a potential difference without an electric field, but not the other way around. This is because, for a small change in the \( x \) direction, the potential changes according to: \[\Delta V=-E_{x}\Delta x\] But this is small potatoes. You can always say your constant \( V \) with no \( \boldsymbol{E} \) is just an artifice. This constant \( V \) is very much a convention: You can always redefine it to be zero everywhere. But not so with the magnetic vector potential. We actually know fermions are sensitive to the vector potential --the equivalent of the potential difference for magnetostatic fields-- even when the magnetic field is zero everywhere, as long as the vector potential has a source line --a thin line of current generating it--. This is called the Aharonov-Bohm effect. In simple terms, it means electrons "know" there is some field there even though there are no electric or magnetic fields. OTOH, electric and magnetic fields are not the be-all-end-all of what can be in space. There are also electroweak fields, strong-force fields, Higgs fields... So, why would the electric field be the ultimate substance of everything else physical that has spatial extension?

I can take care of that. Thank you very much. https://en.wikipedia.org/wiki/Al-Qarada_raid Mohammed raided caravans for a while. Please, illustrate me when Islam considers this a proper behaviour. (My emphasis.) Women can be free... I thought either you're free or your not. If you can be free, something's wrong with your "freedom." This reminds me of that similar, very common, euphemism: "This is potentially dangerous." Something is either dangerous or it's not. "Dangerous" means "potentially harmful." "Potentially dangerous" is about as BS as "potentially potentially harmful." Same with "free." If you're free, you're able to do what you want. If you "can be free," you're able to be able to do what you want. My BS detector went off. OTOH: https://en.wikipedia.org/wiki/Criticism_of_Muhammad#Age_of_3rd_wife_Aisha Is this story true? Is Bukhari right about it? If so, is a 6-year-old child who's still playing with dolls free to take a man in his fifties as husband?

It could've been a proper followup of this: Which kind of was the prophecy that we would have a thread like this.

They all looked like characters out of Jeremiah Johnson --except for the Native Americans.

Great explanation. The best possible. It's very difficult to explain this in simpler terms than these. For a space with dimension n the number of components of the Weyl are the number of components of the Riemann minus the number of components of the Ricci: \[ \#(Riemann) = \frac{1}{12} n^2\left(n^2-1\right) \] \[ \#(Ricci) = \frac{1}{2}n\left( n+1\right) \] For n=3 that gives precisely 6-6=0 components for the Weyl. So no tidal forces in dim=4 if Markus is right and the Weyl codifies tidal forces. And I'm guessing he is.

I was to within a smidgeon of a thought of mentioning Ben Franklin. That's where the convention came from.

Another ridiculously beautiful one is brine pools (underwater lakes). They really look like lakes or rivers of underwater water. --------------------------- From Wikipedia: https://en.wikipedia.org/wiki/Brine_pool ---------------------------------- From: http://valorielord.com/index.cfm/blog/underwater-lakes-and-rivers/

Amazing. Quoted from Wikipedia article:

Exactly so. Actually, the number of events --ticks of a clock-- is the only reference you have any hope for all observers to agree upon. Those would be "classical events" or measurements. Quantum mechanical evolution is a different matter. We cannot directly measure the wave function, but even wave functions quantum amplitudes give consistent results if you assume they transform as a certain representation of the Lorentz transformations. Time is real enough, and it is a dimension. In quantum mechanics you can tie it to just one event by Heisenberg's uncertainty principle. The more energy a random fluctuation has, the shorter it will live, according to time-energy HUP: \[\Delta E \Delta t \geq \frac{\hbar}{2} \] There is no reference system in which you measure half an event, or no event at all. The events are the invariant reference. And if you measure time interval and spacial extension, and thereby calculate proper time, all observers agree on the time it takes.

(My emphasis.) This is precisely what the principle of relativity tells you is not possible. Nothing internal is affected by the system moving at a constant velocity, so no internal mechanism can "detect" that the particle is moving based on any phenomenon, including the decay of the particle. Time dilation and length contraction are the consequence of a symmetry principle, not of an internal mechanism of matter. In the last centuries, we've grown apart from trying to explain physical phenomena in terms of mechanical models, pieces that push, and pull, and swivel against each other; and we've learnt to look at physical theories more abstractly: Mathematical spaces, mathematical objects defined in those spaces, and principles of symmetry. And we've done so for very good reasons. The velocity that you see is not an attribute of the object that's moving, it's a parameter that encapsulates your relation to it as an observer. The particle "doesn't know" it has a velocity, so when it decays, it doesn't do it as a consequence of that velocity. This point by @studiot is very much what I meant by my "it's all in the mathematics, not in any mechanism."

Yusef, I'm interested in holy texts mostly from the point of view of historical criticism. I think they give you clues to the concerns and strife of our ancestors, whether they be Muslim, Christian or Jew, or any other religion. I also enjoy the poetry in them, occasionally. They are literary works of art at some points, political manifestos at another. Not even for a second do I consider that they could be an accurate account of anything. Let alone use them as a proper guide for use in our daily lives. My kind of questions would be like: What kind of man must Mohammed have been? Why did the monotheists in the 6th century's Middle East --first years of the Hegira or الهجرة‎-- feel compelled to raise in arms against polytheism and "stranded" versions of their faith in one God? Why did the Kaaba --ٱلْكَعْبَة‎-- end up in Mecca? Why did the Qibla --قِبْلَة‎-- change? What consequences had the vying for power between Caliphs during the first few centuries of Islam in the later developments into different branches? Very similar questions I ask myself about Christianity and Judaism. I also have faith in archaeology: What you dig from the ground is what it is, far more robust an evidence than anything written in a book. And the reason is I can write in a book now whatever I want, and people now, or people centuries from now, can choose to believe me or not. But if I do this or that, I eat or drink this or that, if I worship to this or that god, the remains of my activity cannot easily misrepresent me and my environment. They are what they are. And they will be there when they're dug out, speaking about me volumes more than anything about myself I write down. And they will be proof of what I did or didn't do. Some data, of course, are lost forever. That, in a nutshell, is why I don't take literally anything my ancestors said.

Oh, boy. I wish there were a filter for the really important questions. So much time wasted on the I'm-totally-confused user!

Doh! You're right. Manganese can't take what's not there.