joigus

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.

You don't need LQG to prove BHs have entropy. The first historical proof was actually a mix between thermodynamic and quantum arguments. Also, you seem confused between the entropy of a BH and the entropy of "particles on their way into a BH." Those are different. You seem to identify "entropy" with "mistakes." Because a portal to another universe would require some control on the parameters of the spaceship going into it. How would we be able to control its direction? Is something like that your question? OTOH, BHs as portals to other universes --or regions of the universe-- is still an open question in physics, so we're not sure they are actually possible. Gravity is not a part of the current laws of particle physics. It's something pretty much "adjoined" to the standard model of particle physics. ------ PS: I had edited this last night and some comments have already been posted very much in the direction I was going.

Looks to me like a redox reaction that you have to balance by identifying how many electrons are transferred from what ion to what ion, and then accounting for H2O ions depending on whether you are in an acid or basic solution. This is called the ion-electron balancing method. The acid --in this case-- or the base in others, is there to tell you that you must balance by using protons. Bases balance by using OH- ions. Is this homework?

Thanks, Phi, especially for "intact". That completely threw me off. Signals from atoms can be obtained without need of ionizing them. That's what an MRI does, for example, in which oscillating magnetic fields get the atom to radiate at low --non-ionizing-- frequencies. There are many other kind of signals you can get from atoms without ionizing them --making them lose their electrons--. Most of those signals from atoms are radiation of different frequencies. In the other case that you mention: More or less, yes. But in this case it's a metal. A metal can be conceived of as many atoms forming a common "molecule" --a metallic crystal-- in which the internal electrons --called valence electrons-- are close to their nuclei, while the conduction electrons form a common quantum highway --a conduction orbital--. Metals have a strong tendency to lose their outer electrons. But they can't get too far off. As you say, the light is due to the conduction electrons finding resistance and heating up the filament, rather than the glass. The glass is heated because it's so close to all this action.

Round?

Frequency of certain quantum states has nothing to do with the frequency of certain quantum events. It's just another way of saying "energy." I agree with Studiot that you gave a reasonably good account of some features of special relativity. But then you jumped somewhere I don't quite see.

I've noticed the same bug. Thanks for pointing it out.

Sorry, I don't understand your question. A waste of time? That's not a physical concept. This doesn't sound like a speculation. It seems to me you're asking a question. We'll help you rephrase, as clearly something's bothering you. In particular, I don't understand what you mean by "surging" or by "stay intake".

You're right. You did say so. I'm missing the second purely electrical one...

As @studiot said, there are two sign criteria. One for charges and another for magnetic fields with respect to currents --the right-hand rule--. It is a technical difficulty to be sure, but nothing measurable depends on it.