exchemist

So what, though? The subtleties of nature are not anything like determining the existence of a country. If you had been a Newtonian physicist, you would have used logic and evidence to "determine" that the kinetic energy of a moving body is 1/2 mv². And you would, a couple of centuries later, have been shown that that was not the case. If you had been J J Thomson, at the turn of the c.20th, you would have used logic and evidence to "determine" that the atom had a structure like that of a plum pudding - only to find out a decade or so later, that that was entirely misconceived. Science has been burnt often enough in history by such changes in understanding that it avoids speaking of truth or reality where a theory is concerned, but only of models that predict the behaviour of nature. These models aim, in that limited sense, to represent physical reality, but they are potentially imperfect, not definitive and always subject to change in the light of new evidence. So it's not really at all like whether a country exists or not.

There may be some misunderstanding here. @studiot is talking about the UK, where I am also located. So the US FDA is not relevant. Here, we have a National Health Service. If someone were to suffer an anaphylactic reaction, after going home from a vaccination, any medical treatment they received would come from the NHS, who would rapidly ascertain that the patient had just had a Covid vaccination. So there is no doubt that the NHS, having administered tens of millions of vaccinations, would know by now if such events were significant. We do know, from the campaign, about various rare side effects of the different vaccines. Everyone has been on the lookout for them and has been reporting them. There is no way that a serious and dramatic effect like anaphylaxis would somehow have been missed.

There seems to be evidence that choosing a booster different from your previous shots widens your scope of protection. Omicron seems to be crowding out delta in the UK, at great speed. What I'm not clear about is whether this means delta will die out. I suppose that if omicron confers immunity against delta that would be expected: omicron would tend to get to a person first and then they would be less likely to catch delta later. But if omicron does not confer significant immunity against delta, I don't see why omicron's presence would stop delta proliferating as well. Maybe someone more knowledgeable can comment.

Does common sense also tell you to ignore all the evidence that contradicts your hypothesis, as you seem intent on doing? And how does your BA in Engineering help you account for why, if, as you suggest, Pangaea is the remnant of a moon, it is only the outer shell that is splattered on the surface of the Earth? Why would an outer shell detach and be preserved, and what happened to all the rock inside? Or do you perhaps think this moon was hollow? Lastly, why pose a question on a science forum, when you are convinced you already know the answer and are not prepared to consider any objections to your hypothesis?

I think fusion would seen as complementary to the intermittent generation sources, to avoid needing to rely on them for more than, say 50% of the demand, the problem being of course the need for energy storage where intermittent sources are used. How do they store electricity from solar and wind in Australia? I agree that we cannot bank on fusion at the moment. For now we need nuclear fission and, in the short term (10-20yrs?) some gas, as coal and oil are phased out. If we do get fusion it won't be for 20years at least, the way things are looking.

No that's wrong. There is instead a fractionation process occurring in the mantle, which you do not mention. Volcanism tends to erupt less dense material to the surface, where it builds up continents, which float on the denser material like rafts. The evidence is that the area of the continents has grown with time rather than decreased. The surface water occupies the hollows where there are no continental blocks.

I don't follow this. Can't have what both ways?

The evidence of geology is that there were separate continents long before Pangaea. Pangaea was only a temporary, and fairly recent, lumping together of all or most of the continental crust. We know this from the numerous mountain-building episodes that long predate Pangaea. So it definitely did not arrive from outer space 300m years ago. Since it covered a fair chunk of the Earth's surface, one would expect it to form a part of a sphere, more or less. But not a "ball", i.e. a complete sphere. Furthermore if it had been a moon, it would have dramatically ceased to resemble a ball when it hit the Earth.

On the point about steam raising etc., I learnt something about that from the other thread. In a commercial machine, the torus is to be surrounded by a "breeder blanket" containing Li that intercepts the emitted neutron flux, making tritium, and getting hot in the process. This heat would apparently be conveyed by a coolant to a heat exchanger that can raise steam for a turbogenerator, rather as in a fission power plant. I don't know what the breeder blanket would be made of. Obviously not just lithium, as that melts at 180C. This breeder blanket concept has not been proved so far, I think, though ITER is apparently going to test some of its possible components. ITER is to be followed by a reactor called DEMO, in which this breeder blanket would be run for real, apparently.

Ha. I tutor pope on erectlocycric leaction mechanism. I not lobot.

OK, so contrary to what your profile says, you do not teach astronomy at a school in the UK. Correct?

I'm out of this discussion now. You have basic errors in understanding, that you need to sort out before you go any further, as many people more adept than I have tried to explain to you.

This seems to be just another marketing video from fusion researchers. I didn't see any mention of progress. We had a thread on this topic some days ago: https://www.scienceforums.net/topic/126240-making-fusion-pay/?tab=comments#comment-1193803 To be honest I am a bit jaundiced now where news items on controlled fusion are concerned. I keep seeing plenty of hype, plenty of "jam tomorrow" - and yet it seems to be still as far away as it supposedly was when I was a child. The discussion in that other thread about Q factors illustrates how misleading some of the claims tend to be. I'm all for continuing to do the research, because of the size of the potential prize, but realistically it is still decades away and progress is glacially slow. I suppose they need to release these reports occasionally for political reasons, to keep the R&D money flowing in, but I don't think we should be fooled by them.

This "block universe" stuff has nothing to do with anything we have been discussing. Suggest sticking to the subject. There are two measurements, that's all I meant. But I'm not really interested in getting into a debate with you about your little story. I'm getting bored with this now. If you can explain the issue more clearly to our poster, go ahead.

I'm just trying to deal with the question this poster is posing, which seems to betray a misunderstanding, very likely the notion of a preferred frame of reference. But feel free to correct the misapprehension in a different way if you think it would be clearer.

Yes, there are two lengths, if you like. The point about relativity, which you seem not to have absorbed, is that measurements of length (and time) are not absolute. There is no single "true" value for them. Any measurement of them depends on the viewpoint (frame of reference) from which they are measured and all are equally "true". If you still can't grasp this I suggest going back to your books and reading carefully what relativity says. Nothing can inhabit two different reference frames at once. So you can't do QM (for example) from the viewpoint of two different reference frames at once either. Which means that relativity does not lead to a superposition of states, as you originally suggested.

I don't know where you are, but in the UK university lecturers are as poor as church mice. And you have to do decent research as well, as @CharonY points out. People do it for love of the subject rather than for financial reward. But I take your point that university students don't require such a large amount of sheer teaching expertise as schoolteachers do.

Incorrect. What you "know" is that, due to the relative motion between your 2 reference frames, you expect a difference in these measured lengths, depending on the reference frame choose to consider. You do not "know" 2 incompatible things, for the simple reason that you cannot be simultaneously in both reference frames at once. Rather obviously.

"Clearly", ballocks. If you change reference frames you start your QM analysis again, with the length ruler appropriate to that frame. You only have a superposition if you have 2 states that are mixed. But in either reference frame, you have only one state. This is why I keep telling you that you can't somehow stand outside these frames of reference when you apply your QM, and say "Look, there are 2 different states". I repeat: any application of physics has to assume some frame of reference, from which it takes its dimensional yardsticks. You cannot use two different ones at once.

You are not making much sense now. I have tried to explain to you why length contraction does not imply any superposition. Nothing is changed, as far as QM is concerned, by one spatial dimension appearing foreshortened in one frame of reference relative to another one. You can't do QM outside a frame of reference, any more than you can do any other physics outside one. A frame of reference is always presumed, either explicitly or implicitly. So in your example, you are in one or the other and your QM maths will come out the same in both, with, say, the x dimension a bit squashed in one compared to the other. That's all. From your other response it looks as if you are labouring under the misapprehension that there is some "intrinsic" or "real" length and that observations made from other frames of reference are an illusion or distortion. This is wrong. I think it is the source of your confusion.

The issue with that is that it will be >50% teaching and <50% science. I mean, you really need to have a skill at communicating, and be able to handle a room full of kids and so on. That's a skill that not everyone has, by any means, and it is quite exhausting. Also it is notoriously poorly paid. But handing on the torch of knowledge to the next generation can be very rewarding. No one forgets an inspirational teacher. Or a really crap one, come to think of it........

Hoho. But it's not a subject as such, to the extent that there are teachers employed to teach astronomy, so far as I know. But I'd be interested to hear what, um, Kevin has to say - and how he expresses himself.

So, um, Kevin, if you have no links with certain schools, are there some schools that you do have links with? I was not aware that astronomy featured in the UK school curriculum.

Far from it. Temperature is often quoted as an example of an emergent phenomenon, yet we know exactly how it arises. As I understand it, it is meaningless to speak of the temperature of an individual molecule, because temperature applies to an assembly of molecules, statistically large enough to form a Boltzmann distribution, in which the probabilities of each state the molecules can occupy is proportional to exp(-e/kT), T being the temperature. Other bulk properties of matter that arise from statistical distributions of atomic-scale entities - and there are lots of them - would be similar.

Thanks. That's informative. What they call the Breeding Blanket seems to be the crucial component. That has led me to this paper,https://nucleus-new.iaea.org/sites/fusionportal/Shared Documents/FEC 2016/fec2016-preprints/preprint0228.pdf according to which ITER will test a design for this blanket, which will then have to be scaled up and proved in something called DEMO, which is a reactor to be built only if and when ITER succeeds in achieving stable fusion. It seems to me it is going to take several further decades of development work before we have commercial fusion power. If we ever get there.