exchemist

What groups are these that American scientists were finding themselves in, in 2009, that would prevent them replying with honesty to an anonymous survey? I cannot envisage how that would work.

Why would an atheist, in the USA in 2009, have felt the need for courage to respond honestly, in an anonymous survey?

But you could easily do studies in liberal democracies where no such persecution or social expectation applies. This would be true of anywhere in N America, W Europe or Japan. There is this Pew study, conducted in the USA for example: https://www.pewresearch.org/religion/2009/11/05/scientists-and-belief/ What this does not seem to correct for is any correlation between religious belief and level of educational attainment. It may be also that more educated people tend to be less religious, regardless of subject studied.

What does it mean to “harvest” a direction? You must mean harvesting energy, surely? If this is a quantum system in its ground state, you cannot extract energy from it without breaking up the system. You have a form of zero point motion. You can’t extract energy from that. But if you have not yet learned any quantum theory you may find this hard to understand. All I can suggest is to read a bit, e.g. this link: http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/hosc4.html Don’t be scared by the maths, just read the text.

Well I must say that video seemed to make perfect sense to me, as a total non-expert in this area. Sabine's key point seemed to be that there is a vacuum energy inherent in GR that is just a constant of nature, arising purely from GR in a self-contained way, with no connection at all to the energy of vacuum fluctuations in QFT. Is that controversial?

No I don't think so. See the Wiki article: https://en.wikipedia.org/wiki/Time_crystal and especially this passage: Time crystals do not violate the laws of thermodynamics: energy in the overall system is conserved, such a crystal does not spontaneously convert thermal energy into mechanical work, and it cannot serve as a perpetual store of work. But it may change perpetually in a fixed pattern in time for as long as the system can be maintained. They possess "motion without energy"[16]—their apparent motion does not represent conventional kinetic energy.[17] I'll admit I know nothing about time crystals apart from what I have just quickly read, but it looks to me as if these things exhibit motion in their ground state. The definition of a ground state is it is the lowest energy state allowed for the system. From that it follows that energy cannot be extracted from the system (unless you break the system up, I guess, which would be a one-off exercise). You have much the same thing with the zero point energy in a harmonic oscillator, or, to give a real example, in the vibrational ground state of a diatomic molecule. There is still residual motion, even at absolute zero (hence "zero point"), but none of it can be extracted as energy.

No, this is wrong. You need to understand the difference between excitation and ionisation. Photons are often absorbed without having enough energy to eject an electron. They just move it to a higher, but still bound, energy state. This creates an excited state of the atom or molecule that has absorbed the photon. The whole of spectroscopy involves processes of this kind.

I wonder, though, whether this question may be about something else, viz. the "elasticity" of the current-carrying electrons in the circuit. For instance is the voltage is at its maximum value at one end, what will be the phase of the voltage 10 metres along the wire. Will that also be at the max, or is there a phase lag due to the compressibility of the current carriers?

Hard to know where to start with this gibberish. Almost everything you say is wrong, almost as if intentionally so. Just to take one point, there is no photoionisation in the retina of the eye. Photons are absorbed by proteins called opsins, which thereby enter an excited state and change from one isomer to another (cis ->trans). The isomerised version then undergoes a chemical reaction with other molecules to start a cascade of biochemistry, resulting in a nerve signal. This is not photoionisation.

There is apparently a meaning relating to an Ancient Greek theory of sight, in addition to the more, er, Sid James sense of the word.......

OK, I'm trying to follow this in the context of a permanent magnet. I'm not finding the motor analogy very helpful (sorry, my background is chemistry rather than engineering). I'm aware that ferromagnetism arises due to aligned, unpaired electron intrinsic "spin" and orbital angular momentum. So I presume the "current" you refer to in this case would comprise the "spinning" (not really but let's call it that) and orbital motion of the electrons. Is that right? But it seems to me this aligned angular momentum does not lead to an overall E field external to a bar magnet, which can interact with a nail some distance away. Or does it? If, as you say, the energy in the magnet that changes, when the nail is brought close to it, comes from the E field, what change do we get at the atomic level? Are we saying the quantum states of the unpaired electrons drop slightly in electrostatic energy, e.g. their mean distance from the nucleus reduces fractionally, or something like that? As you will see, I am trying to get a physics tutorial on this from @Mordred, who is I gather a professional physicist (respect). It looks to me so far (i.e. pending what I may be about to learn) that I may have been a bit too cavalier in strict physics terms in claiming the work done by, and on, your magnets comes from what I have been calling "the magnetic field". We are now into a discussion of the E field and the B field and where exactly the extra energy due to magnetisation resides in a permanent magnet. I think though that, in terms intelligible to a non-physicist, we can still say it is the extra energy in the fields due to their magnetised condition that rises and falls as work is done. But let's see what brother Mordred comes back with. I just hope I have enough grey cells left, at approaching 70, to take in a change in my mental picture of how this all works. 😀

OK, but what gives rise to the E field in this case and what form does it take?

I don’t think that matters. But let’s say it has been brought up from infinity (a concept physicists seem to like), held in place on the table and then released. Work is done against friction as the nail moves towards the magnet. What provides the energy?

If a nail is attracted towards a permanent magnet, doing work against friction, where does the energy come from?

Right. But, to be clear, there is energy in the magnetic fields, which can be made to do mechanical work, for instance in my example of the nail being drawn towards a permanent magnet, against the force of friction with a table top. My attempt at analysing the operating cycle of this reciprocating machine was to show how energy is alternately drawn from and returned to the fields generated by the pair of opposed magnets, so the net effect, over one operating cycle, is as you say, no net work done by the magnets and a mere transfer of input mechanical work to output mechanical work.

Yes, it would be good to understand exactly what @swansont means. I suspect it may be the simple point that a magnetic grab, once it is clamped onto an object, does no work when the crane lifts said object. However, when a permanent magnet on a table top draws a nail towards it, against the force of friction, work is clearly done. That work, it seems to me, must be drawn from stored energy in the magnetic field.

That's interesting. I had always understood that magnetic fields have energy, as for example in the stored energy in an energised electromagnet. If they do not, where does the energy come from when an object moves towards another under the influence of magnetic attraction? And you yourself say a magnetic field has an energy density.

Information is related to entropy, but is not energy and can’t be “turned into” it. You don’t know what you are talking about.

Well, I had no idea rapidity had a technical meaning in the context of relativity, so I've learned something already! But having looked it up here: https://en.wikipedia.org/wiki/Rapidity, I'm definitely going to leave it to you chaps in long trousers.......

This abusive approach does not seem likely to make a person “repent and turn to Christ”. Surely it is more likely to confirm them in their low opinion of religions and religious people generally, isn’t it? From a stylistic point of view, some paragraphs would help, too😉

Look, from all your posts it is plain you have a really unhealthy relationship with food. That previous picture you posted on the 14th of March was positively disgusting. And now you ballock on about eating whole lemons and limes on their own, which is nuts and certainly nothing like part of any reasonable, balanced diet. The acid alone will screw with your stomach. I don't know what you are doing on this forum. You've been given all the advice you need long since. Go and talk to a dietician and act on what they say. Stop trying these random daft things and then coming here to obsess about it. I'm sorry, but I've really had enough of this crap.

Suspect the biological question was to open the door to these dubious social ideas now being advanced. We shall see.

But you are not only asking questions. You are making contentious assertions - or at least advancing contentious opinions - too. You say it seems that the male of the human species is becoming less relevant. You cannot expect us all to go along with this without challenging it, because it is patently ridiculous. The human male has dominated human societies for millennia and a quick glance at the sex of those occupying positions of power and influence in modern societies will show you they are still predominantly male. We can't just answer your questions, if your questions start from a false premise. Surely you must understand that?

OK. As I understand it, the idea is inserting the tab, or finger, causes the magnets to be attracted to it, instead of repelled from one another as they are in the previous phase of the motion. If we describe the operation in terms of an engine cycle, there are 4 phases:- 1) magnets close together no tab inserted, high energy of the field 2) magnets have moved apart due to mutual repulsion, reduction in field energy. Work imparted to output shaft 3) tab or finger inserted into the gap, causing magnets to be now attracted towards it, with further lowering of field energy. More work output to the output shaft (and some work output to the input shaft as well, due to the attraction) 4) tab removed from the gap between the magnets, which are now close together. This replaces the force of attraction to the tab or finger by mutual repulsion of the magnets, which are now at close separation, i.e. back to (1). It is this step that requires the substantial work input which returns the stored energy in the field to its stating value. Failure to realise the work need to do this is what can lead the incautious designer to think he has an over-unity machine, as the other steps all involve extracting work from the magnetic field. At least, that is my energy-based analysis of this machine.

Over unity is the same thing as what is traditionally known as a “perpetual motion machine of the first kind”, i.e. one that claims to break the 1st law of thermodynamics. So it’s not a slur. There have also been ideas for perpetual motion machines of the 2nd kind, which claim to break the 2nd law of TD instead. As I have mentioned, it can be good sport to spot the flaw in the logic of the designer. A rule of some patent offices, e.g. the US one, is patent applications for perpetual motion machines will only be accepted if accompanied by a working model. Which they never are, of course. So recognising perpetual motion machines is something patent office examiners (as Einstein once was,incidentally) and patent agents have to be able to do.