studiot

I felt that the video, whilst strictly correct in one sense, was disingenuously hiding some things, whilst making too much of a meal of others. In this respect and bearing in mind @Phi for All's recent comment favouring the written word over videos: References to a transatlantic telegraph cable bears little relation to the working of a power supply cable and could have been omitted. It was unjustifiable showmanship. Whilst they did say that the battery and the light were 1 metre apart, they di nothing to bring that out, except at the end in a smart alec, aren't we clever kind of way. They failed to mention the fact that the disparity in the length of the supply and return conductors was so large at 1 : 300,000,000. I can't think of any normal power supply connections with such a ratio. Much closer to 1 : 1 would be the norm. So an interesting bit of electrophysics would have been to analyse for two cases, the one they showed and one with both conductors at 300,000,000 metres in length. All in all I prefer the more measured discussion of the topic by Francis Sears (MIT) in his famous book 'Electricity and Magnetism'. Francis also make very clear the distinction between potential and emf.

There was no failure in my case. That is my point. The metal mechanism of the punch has a soft plastic catch plate for the punched paper disks that is fitted underneath by stretching it slight over the base of the metal frame. Clearly it had to be only stretched in the elastic region or it would not the snap back into position, gripping the frame. Taking it into the plastic region would result in a permanent set so it no longer gripped its place tightly. I was simply reflecting on how many plastic cases of many items and gadgets these days rely on this.

Thank you for your response. Yes I can confirm that all three incidents were pretty immediate following rhe shot. (Isn't that what happens in anaphalaxis as opposed to any old reaction ?) UK innoculation staff are all trained to watch for and be able to deal with any reaction followng the origninal Dumfries case. Of course I should have specified adverse reaction, after all we all hope to have some (favourable) response to the shot. I had no personally detectable response to my first two shots, but on the most recent third (booster) i had no response before I went to bed the night of the shot but has a slightly sore area on my arm at the innoculation site the following morning. This faded over the following couple of days. The actual reports are numerically exact but not gained from the covid monitoring programme but from the hospital's own incident (of any sort) monitoring programme. Every reportable incident is reviewed, categorized and catalogued for any appropriate follow up action.

As I was refitting the soft plastic debris catch plate to my hole punch, I reflected how often we use and rely on the elastic properties of so called plastic materials. If they genuinely operated as a plastic material there would be instant failure of the component. Comments ?

Thank you for response, which was even briefer than my original post. Since you wre the only one interested enough to respond at all +1. However you have jumped to some unjustifiable conclusions in your response, particularly as to the source of my information and the phrase "promptly and successfully treated" , which was indeed absolute and correct, rather than an overly-favourable speculation.

1) Is there a wheel lock and if so is it unintentionally engaged ? 2) Since you can detach the wheel, is there any relative movement or 'backlash' at all between the two moving parts ? 3) You might be able to free it up by spraying with silicone dry lubricant and hand twisting the two parts back and fore. 4) Are all the wheels locked or just some ?

For those that might be interested. In the area covered by our local district hospital they have now administerd about 245,000 covid vaccinations, mostly Pfizer with some AZ and lately some Moderna. In they started this in January 2020 and since then there have been 3 anaphalactic like reactions, none with serious lasting effects. Of these one proved to be actually an epileptic episode, that would likely have happened anyway and nothing to do with the vaccination. The other two were promptly and successfully dealt with by the attendant medical staff.

Not at all sure what this question is about, but usage varies quite considrably over Europe. The reaction of the sales person to the question cheque, cash, credit or debit or charge card, phone has several complex factor and so varies considerably. Perhaps the most important is whether you are dealing with a large organisation or a small trader. Many employees of large concerns can't be bothered to implement anything that requires a decision or extra work for themselves, even if they have the authority. Flash the card of the phone, job done, no work for them. On the other hand small concerns used to be more receptive to offering a discount for not using a credit card. I have a personal policy of offering a small trader the choice of, whichever is cheapest for them, to try to support local business of multinationals. Until recently they usually preferred cash, but changes to banking charges mean that many now find it cheaper to ask for a credit or debit card (some find one card cheaper, some another it just depends upon their bank). But just this week Amazon has announced it is ceasing accepting credit cards, due to high fees (0.1%) has been mentioned for them. In the UK people have accepted all these forms quickly and readily, as they did in the Netherlands. Recently I had no problems on a bus in the Netherlands buying a bus ticket with a credit or debit card, but in many places in the UK you need a phone or a special charge card for your bus ticket. But the first time I visited my friends in Germany I was suprised that the Germans disklike credit cards and not many places accept them, though more so do now. It was explained to me that antagonism towards any form of credit is deeply ingrained in the post hyperinflation german psyche. Ireland is pretty similar to the UK. France and Spain are somewhere in the middle between UK and Germany. Italy is similar to Ireland.

Actually you can, but only if you try some theologians who are also real physicists. Such as Michael Heller John Polkinghorne KBE. Not the twaddle from this member who seems to want to outdo Trump with his tweets.

Well, I did wonder. But Google has plenty on 'politis' a Greek concept of a citizen and his rights and duties. So my question stands. As regards lobsters, I remember some years back visiting the Aquarium and Marine Biology labs whilst on holiday in Pembrokeshire. I was impressed with the work and projects they had going on with local schools. One project was a huge tank for the study of the marine environment. Listening to the guide I learend that the marine invornment was far closer to the 'law of the jungle' than ouit own. Everything was easy prey to something and even fierce looking creatures like lobsters would be quicly gobbled up if they strayed too far from their shelter. Definitely a constantly dangerous and aggressive environment.

Can anyone tell me what is meant by Politis in thread title ? It's all Greek to me. I also wonder if, having been mentioned in the current BBC drama, JP will become a latter day Harvey Smith ?

The response from the art world. https://www.bbc.co.uk/news/uk-england-derbyshire-59318780

Hi Chris, the two most important Laws in Science are called the first and seconf Law of Thermodynaics. They are the most important in my opinion, because they enabled the industrial revolution. The first law states "You can't get something for nothing" or "There is no such thing as a free lunch" or "You can't win, you can only break even". The second law states "You can't even break even you can only loose" So think of an ordinary coal or log fire. In theory you could collect all the heat from the combustion and use that as well as the portion you actually use. But the first law tells you that you can only get out what you put in. That is for a specific amount of fuel you get a specific amount of heat and no more. However the second law bites you in the ass because some of the products of combustion appear as a gas and go up the chimney. But to make a gas from a solid or liquid (fuel) requires an input of heat energy. This heat can only come from the heat of combustion as ther is nowhere else for it to come from. If the combustion products did not go up the chimney they would collect in the fireplace. Similarly if you took all the energy out of the water passing through a turbine at the bottom of a dam, the water would unot have enough energy left to flow away and you would be faced with a flood. At each stage of any process there Mr 10% (or worse) always takes his cut. So every time you recycle your hydrogen you would loose 10% (it would actually be more). Does this help ?

You mean Vance Packard ?

That is not, and never has been, the situation I described. As it is clear you are not going to even attempt to follow my question, let alone begin to answer it, we are done here with your fairy tales.

An excellent. and satisfying short, summary of what everyone has been saying to you. +1

The question you asked me on Nov 9 was, “Re phrasing for absorbtion, Are you telling me you that the electron can 'jump' before absorbtion takes place ? Surely the fundamental question is Which must happen first, absorption, or the electron transition ? “ The question strikes me as asking, Which came first, the shell or the nut? For one thing, you can’t tell precisely when the transition took place because of the impossibility of observing the event and the terms absorption and transition are essentially synonymous. My answer was that I can’t possibly see how anyone can time the events. I could have guessed and said absorption comes first. I suspect that is the answer you were looking for but that is not an answer I can support since I see the timing as unknowable. I have no idea where you are going with your “spectral lines” example so I expect you to explain whatever you are trying to explain. The problem can be viewed theoretically as a problem of math and this has been done by Carver Mead. Carver Mead is a former colleague of Richard Feynman and well known for his innovative work with transistors and IC’s so I suspect he knows what he is talking about. Mead's calculations are time-symmetric with waves going simultaneously forward and backward in time so the concepts of first and last are meaningless. The calculations can be found in the book “Collective Electrodynamics” by Carver Mead in Part 5 “Electromagnetic Interaction of Atoms.” The time of duration in his equations is represented by the letter alpha. I don’t understand Mead’s calculations well enough to give a reliable explanation but it is obvious from his descriptions that he has moved on from photon theory. This is not quite what I am saying. I am saying that two separate particles with different quantum states can share a common existence as if they were side-by-side even though they may be light centuries apart. More specifically, an electron in one part of the universe can share energy with an electron in a another part of the universe by means of entanglement so long as they reside on the same light cone. But, with all that waffle, you still have not addressed my question. You have just tried to sweep it under the carpet. I would hazard a guess that everyone else reading this thread can see that I have tried to ask the same question in different ways in order to try to make it as clear as I possibly can. Rephrasing sometimes helps. However you persistently address different questions, from the one I asked you. Of course not, you are answering a differnt question that you posed to yourself. Easy sidestep. Whether we are able to measure something or not has no bearing on that something itself. It would still be the same, even if we did not exist at all to attempt a measurement. So as not to appear grumpy and churlish I will offer a line of analytical thinking in more detail. A great many of our achievements in Science and Engineering are founded on the technique considering a very small piece of something and then considering what happens to our theory when we shrink that piece to zero. So consider an electron gaining energy by absorbtion, with a start time and a finish time separated by a very small time interval. (Note I have not specified absorbtion of any type of EM radiation, just energy from whatever source. Such non EM sources undoubtedly exist and are studied in basic physics.) Now QM tells us that the electron cannot make the transition to the higher state until the entire quantity of energy is available, whenever that occurs. Perhaps it cannot even start that transition until that point in time is reached. So we now consider a transition of the electron with its own, yet to be defined, start and end points, which correspond to different states of the electron (by definition) Put these together in a critical path analysis and then see what happens as you shrink either or both to zero. 'Instantaneous' would require both these very short time intervals to be exactly zero. Which would imply that the electron is in two different states at once. Still the same question, just with more detail. Schrodinger asked it way back about his cat.

+1 for another well thought out and balanced assessment. (Background sounding of Copland's "fanfare for the common man") You have advanced the cause of rational thinking by "non experts" substantially. More so in my opinion that the subject of this thread, even though I have little symapthy for him. Hi MigL, I am going to both agree with you and disagree with you. Yes I agree that I find current Psychology , as a Science, at about the level of Physics in the time of Francis Bacon. They are just beginning to find their way by feeling for the variables/parameters to observe and consider. As such they have yet to develop any really effective tools, just as mechanics was before Gallileo and Newton. Today we know a lot more about mechanics (who would be brave/foolish enough to say we know everything ?). In particular I am suprised at your declaration of repeatabilty. Yes it is a desirable outcome, but not always attainable, even in mechanics. We know of at least three factors that mitigate against the possibility of repeatabilty. 1) Statistical variation, leading to the development of limit state theory amongst other techniques. 2) Chaos theory leading to multiple (unrepeatable) outcomes. 3) Catastrophe theory, leading to uncertainty of timing of a mechanical outcome.

I tied mine once nearly 2 years ago, to the correct tension and have not needed to tie them again. The masks have now been through the wash at least once a week since then.

My wife did a similar thing, except she cut up some old tights for the material to make the stretchy ties at the back. She has also been experimenting with the metal strips recovered from the hospital blue masks which are re-deformable. As a matter of interest the blue masks survive trips thropugh the wahing machine.

I agree but this is a duplicate thread of this one

Ok so I have been doodling over the weekend, but sadly did not get as far as I had hoped. So here is the next part. Fig 2 is a repeat of Fig 1 but introducing two coordinate systems. In the red corner we have the red system. x', and in the blue corner we have the blue system x. Note the constant p yields a 'transfomation' equation between the two systems. We can also show that the the distance between A and B have the same value in both systems, following the equations in Fig1. That is it is invariant. I will return to the x' = (x - p) equation in more detail, when we get on to motion. In Fig 3 we strike out in 2 dimensions, with two displacement constants, p and q. Now that we are using the full extent of our graph paper, I have tilred the line AB, shown in green. Hopefully it is easy to see that the length of this line is [math]\sqrt {{{\left( {{x_B} - {x_A}} \right)}^2} + {{\left( {{y_B} - {y_A}} \right)}^2}} = \sqrt {{{\left( {x{'_B} - x{'_A}} \right)}^2} + {{\left( {y{'_B} - y{'_A}} \right)}^2}} [/math] although the coordiante differences are different for the red and blue systems. Displacement of a coordinate system is a 'permitted transformation' that simply move the origin about on the graph paper. The other permitted transformation is a rotation of the soordinate system, as in Fig 4 I have gone explicitly through the geometry to show how once again the length AB or its square AB2 is invariant, regardless of the angle of rotation. The key to this is to note that the length AB is the common hypotenuse to two triangles, ABC in the blue system and ABD in the red system. So for rotation also the length is measured the same in both systems That wraps up the static situation, but what ae we actually doing ? We are drawing lines on a piece of graph paper. All lines on that graph paper have a length measured in, say, cm. That is both axis lines, gridlines and plotted lines. To attach meaning to this look at Fig 5, which is a cooling curve for some substance, and a 'plot' of temperature against time. What units is the distance along the curve between points A and B measured in ? Well like all lines on the graph paper, it is measured in cm But, you say, the axes are in seconds and degrees C. No they are also measured, on the graph, in cm. Bot axes are subject to a scale factor (constant in this case) that introduces the necessary conversion of units. Cm to seconds and cm to degrees, remembering that we can only plot cm on the graph paper. This is where you question about c comes in. c is a velocity and velocity is a (variable or constant) scale factor converting time to length. The next installment will introduce moving coordinate systems, which are the basis of relativity. There are three things we must take forward from this. Firstly that there are invariants that are measured the same in all coordinate systems. Secondly The most important one is a function of coordinate difference, not the coordinates themselves. Thirdly that all we have been considering is Geometry, as in the shape and size of things.

And yet they are popular in Scandinavia. I have no idea what you mean by this ?

Some explanation of your diagrams would help and perhaps draw more discussion. I, for one, have no idea what you are showing in your diagrams. Perhaps also you could fill in the blank space following your here is some more comment ?

I suggest another way of looking at it is to say that classical mechanics (of the sort we have been talking about) is about localisation, quantum mechanics is about delocalisation. I was at Loughborough in 1968, 69 and 70. The Chemistry department was dwarfed by the Chemical Engineering department. The Physics department was even smaller than the Chemistry. But that is all a long story.