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Everything posted by studiot
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Thanks but that is totally illogical. Why should the sofware offer me (or anyone else) the title of an existing thread? I typed my perfectly good title into an empty box. Some fool chose to make the software change this and substitute something else. Here at this foprum I suppose it is just funny. But programmers that write software like that can ( and have done) kill people. Suppose a 'smart' petrol pump substituted diesel for petrol because that was what the last customer had? Or even worse the other way round.
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Well yes it was a thread I started some while back. But so what. I clearly typed the thread title into the title box. It will not start the thread without a title. Then I concentrated on the meat of the OP in the proper box. Why should I need to look back to see if the computer was going behind my back to change things? It was more by good luck than good judgement that I noticed the substitution and edited it back to what it should be.
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That assertion would earn you a fail in (serious) Mathematics. Have you heard of equivalence classes? https://www.google.co.uk/search?source=hp&ei=e4QUWuq4C8ScgAaG8q7YBg&q=equivalence+classes&oq=equivalence+classes&gs_l=psy-ab.1.0.0l10.1337.5286.0.8989.19.13.0.6.6.0.190.1402.6j7.13.0....0...1c.1.64.psy-ab..0.19.1553...0i131k1.0.JsrJqbw1DHk
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Hello Outrider and Geordie, and thanks for the comments etc. @geordie, I'm still trying to put pen to paper for your next installment. Won't be long now.
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I just posted a topic in Earth Science. But the software here replaced the title with one from many weeks ago. It left the body of the text unchanged.
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Headline says it all Beach that vanished 12 years ago in a storm reappears overnight. Mind you it could only happen in the Emerald Isle https://www.msn.com/en-gb/news/world/irish-beach-returns-overnight-after-vanishing-in-storms-12-years-ago/ar-BBFqwut?ocid=spartandhp
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No one man can understand it all these days. I have read somewhere that one of the ancient greek philosophers was the last man on Earth who could understand all known knowledge. That is why we need to talk to and equally important listen to each other.
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Yes I had lots of problems with writing technical reports incorporating photos and diagrams etc, in Word. That is where I found out those methods I mentioned. Incidentally opening or pasting into wordpad can cut a recalcitrant document down to size.
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Some tricks I've found with recalcitrant Word things over the years. 1) Save the doc as an RTF file. Open the RTF file. Resave that as a new doc. 2) Copy (use the Windows select and copy function) the entire doc or the bad part of it. Open a new window of Word wiith a blank doc. Paste the bad doc into this. Sometimes simply opening a neew balnk doc in the original Word window and pasting into that is sufficient.
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Am I glad I got out of this thread.
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Since the OP has not bothered to continue dscussion with me for my last several posts I can't see any point my continuing in this thread, despite the directed effort I put in. This is his loss since if he had looked up Malus two mirror expreriment I had linked to, he would not have needed to ask some of his most recent questions. I'm sorry I bothered.
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I don't think spin quantum numbers need be involved - do photons have them and aren't they discrete> The circle of transverse vectors form a complete continuum of states around the axis. It is the change from state to state that is quantum.
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Analysis is (passively) reporting on what is already there/happening. Synthesis is actively creating something that is not (yet) there or moving something to be in a specific place. My two examples for discussion involve the latter. Note I didn't say that both max and min were necessarily involved. But surely the great grandmaster of uncertainty - Heisenberg - has a greater than sign in his principle? So any amount of uncertainty that is greater than the minimum value will conform to his principle.
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Swansont has now said twice that photons do not act as classical point particles in these circumstances. This is the key to understanding polarisation from a photon point of view. You have to move the probabilistic quantum mechanics. Then the explanation is the same as underlies all quantum effects. Since this is Dalo's thread I have presented principle only, although the mathematics can be shown to achieve the same result as classical wave theory. Fig 1 Shows a standard unpolarised transverse wave with the electric vectors ranged evenly around the propagation axis. Fig 2 Shows the classical view of a vertically polarised wave. It has electric oscillations only in the vertical direction and that's it. Fig 3 But in quantum mechanics all the other vectors still exist, however they are shown dashed.. That is because QM regards each as valid state. It is just that only one state is populated. However in QM every state has a non zero probability of being populated. Such a situation only becomes apparent when the light interacts with something, such as a slit. Fig 4 Shows a vertical slit where the probability of transmission is 100%. Fig 5 Shows a slit at 45o, where classically the probability of transmission is zero, but in QM the probability is 50% half the photons move to the 45o degrees polarisation level and half are absorbed. This also explains why the exist phtons are now polarised at 45o
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Thank you for your thoughts, Prometheus. Like most your first thoughts jump to analysis (measurement in this case). That is no criticism. Any thoughts on my examples from synthesis, which all too often seems the poor relation in technical discussion?
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Just to reinforce what John Cuthber said. It is only the electric component vector of light that plays a part in these effects. Bragg also explains this in his video. The simplest way to play with polarisation is Malus' Experiment. https://www.google.co.uk/search?source=hp&ei=ifsRWrRw7IyABt3hqKgO&q=malus+experiment&oq=malus+exper&gs_l=psy-ab.1.0.0j0i22i30k1l5j0i22i10i30k1l2.1809.4225.0.7143.11.11.0.0.0.0.260.1705.1j8j2.11.0....0...1.1.64.psy-ab..0.11.1692...46j0i131k1j0i46k1.0.rJABLl3UJX0 Here also is a pic which shows the effect of finer and finer gratings on diffraction.
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It wasn't a gesture, it was sincere. Bragg explains how the grating works in his video, when he says that there is a regular pattern in crystal so the crystal is anisotropic to the passage of light.
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A not so small discrepancy in Relativity of Simultaneity
studiot replied to Truden's topic in Relativity
Then you can tell us all what it was, without all the theatricals. I stand by my conclusion that Noone will award red points for genuine responses, right or wrong. It's been literally years since I last posted one. -
Let me thank you for answering my question simply and well, +1 There is nothing to apologise for, but as iNow commented, yesterday was Saturday and I had many other calls on my time. I needed 20 minutes to watch the full video. I have not seen Bragg in action so thank you for introducing me to this source, the demonstrations, though old, were fascinating and well chosen. In my eyes he was both clear and understandable in his explanations. These seemed to me to answer both your questions that have given rise to long threads. So well done for attempting to replicate the experiments. Let's try to all stop squabbling and to pin-point your difficulty instead so that it can be sorted. I cannot believe that you are not interested since you have put so much effort into this. However remember that it may take a little time for responses so be patient. I still owe another member the next long installment of longish series about another subject, from last Sunday..
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A not so small discrepancy in Relativity of Simultaneity
studiot replied to Truden's topic in Relativity
One thing only saddens me. That you seem not to be genuinely seeking discussion and resolution of your point, rather you seek to provoke reaction so that you can ridicule others with more knowledge than yours, whilst at the same time sidestepping from your earlier statements. I made my last post for very good reasons, which anyone claiming to work on logic problems would normally ask "That's an interesting comment why did you say that?" In particular I stripped out simultaneity from the ladder paradox so that it would not obscure the Physics. Further I deliberately introduced a situation where no ladder of any length in any frame could in your words "pass the garage". I have pointed you at the correct resolution of the paradox which basically relies on an incomplete analysis of the situation, but without stating how explicitly. I take it that you are not actually interested in this. -
I am promoting discussion about the question What is a uncertainty in Science? Uncertainty is definitely linked to probability. Probability is a definite number (one number) between 0 and 1 So it is tempting to think that if the probability is p then the uncertainty can be defined as (1-p), but this doesn't really work. Consider a cubical shaped object. What is the uncertainty of position when I place it along a line? Let my cube be a model of my car and of side L. Now the UK rules for parking said car state that if any part of the car is on a yellow line it is illegally parked and I could be subject to a fine (or worse). So what is the allowable uncertainty in positioning my car when I park it? Now let my cube be much smaller. Let it be the rider on a beam balance. What is the uncertainty in positioning this rider so that the balance operates correctly? In both cases the uncertainty could be huge. The car could be 100 miles form the nearest yellow line. But there is a minimum distance for placing the centre. Which brings out two points. Probability is just a number. It has no units or dimensions. Uncertainty is usually expressed in the units of the measurand and generally has dimensions. Uncertainty is usually expressed as a range with one end a maximum or minimum.
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A not so small discrepancy in Relativity of Simultaneity
studiot replied to Truden's topic in Relativity
Wikipedia is not the best or most reliable source in this case. So thank you for trying. Another (and I think better) view is that the same physical reality must pertain in all frames. This is not about Schrodinger's cat and QM. Relativity is exactly deterministic. A proposal that suggests something different happens in different frames is flawed, usually by inadequate consideration of the mechanics of the situation. The same reality must happen in all frames (not events they have a special meaning) That is what is meant by the phrase the laws of Physics must be the same in all frames. Einstein himself concluded that must place certain limitations on acceptable laws of physics. If something is impossible in one frame it it impossible in all frames. I suggest that there is too much emphasis on the doors, which are really a distraction. The doors could be switch activated vertical light curtains effectively instantaneous in action if their height is tiny compared to the length of the ladder. Alternatively the whole paradox could be simplified, as I'm not sure there is a clear understanding of it here. So let the exit door of the garage be permanently closed. Then there is no need to have an opening / closing mechanism or a discussion about simultaneity of door operations. Jack and Jill first offer up the ladder to the garage and butt it against the exit door, through the open entrance. The other end of the ladder can be seen to stick out from the entrance side of the garage. All this takes place in the common frame of Jack, Jill and the garage. Then Jack picks up the ladder and walks slowly back a suitable distance to begin his run. He runs very fast forwards and notes that the ladder has not changed its length but the garage appears even shorter in his new frame. So he concludes that the ladder still will not fit into the garage space. Jill remains by the garage and notes that the garage has not changed in size. She also observes Jack running towards her, carrying a ladder, now appearing shorter than the garage space. So to Jill the ladder will now fit inside the garage. The resolution of this 'apparent paradox lies in the word apparent, appears and appearing. Appearances can be deceptive. Ask yourself how do Jack and Jill make these measurements and you will find that both have to be adjusted by the Lorenz gamma factor to be brought into a common frame for comparison. -
Like the pics of the discharge tubes, thanks +1 Sensei.
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Space (s) -the third form of matter
studiot replied to Dr. Charles Michael Turner's topic in Speculations
Not all. I'm a don't care, since it makes no difference to me. And I sleep better at night for not feeling the urge to prove or disprove the unprovable. (Didn't Oscar Wilde say something like that?) -
1967 I built my first geiger. Gosh was it that long ago? I don't think I even own one now. Anyway here is a good simple explanatory article. Don't forget geiger tubes use high voltage, when you are thinking about radioactivity. Yes readioactivity does degrade insulation over time.