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Showing content with the highest reputation on 01/16/20 in all areas

  1. 3 points
    Sorry if I'm confused but I think the analogy is 97% are saying the plane won't make it and you are saying we should believe the 3% who claim everything is ok.
  2. 1 point
    Although it would be a leap of faith, how reliable would it be for a human to strap on an easy to wear magnetic jacket/belt and jump down a strait tube of which the temporary Eddie current would slow the person down according to Lenz's Law so they would reach the end of the tube at ground level reliably and without injury? Sort of life a Fireman's Pole, only without the pole.
  3. 1 point
    More often than not they forget to mention Observable universe.
  4. 1 point
    I think many members are probably tired of hearing for the umpteenth time someone saying that they don't believe in climate change because they want to.
  5. 1 point
    But that is the exact opposite of the current situation. Evolution has, indeed, been obvious for millennia. What was missing for all that time was an explanation (a theory) of how and why it occurred in the way it did. It took the insights and evidence gathered by Wallace and Darwin to change the paradigm. No it isn't. Testing relativity to the extent it has been confirmed has required incredibly complex and sensitive experiments. Multiple lines of evidence from different experiments have all turned out to be consistent with each other and with the theory. (Keyword: consilience.) The same is true in climate science. Different ways of modelling and measuring the effects have all produced consistent results. For example, measuring the spectra of radiation transmitted from the atmosphere (using satellites) is completely consistent with the predicted effects for the measured levels of CO2; the measurements of industrial output (using, for example, GDP) matches growing levels of CO2 production; models of how climate is affected by insolation, greenhouse gas levels, albedo (snow, volcanic eruptions, cloud cover), etc can be matched with past conditions, and on and on. You can keep saying that there is doubt or "another side" or how poor the science is. But until you provide some evidence, these assertions have no value. Especially when weighed against the mountains of scientific evidence. Maybe you are confusing weather with climate? In some parts of the world, climate change is likely to result in colder weather (or, at least, more frequent extremes of cold weather). Remember, climate change is about average temperatures increasing, not about "everywhere getting hotter, every day". The last decade was confirmed as the hottest on record: https://www.bbc.com/news/science-environment-51111176 (but even a decade could be counted as weather, rather than climate).
  6. 1 point
    Since the induced field depends on the rate of change of the field in the material, that means the retarding force should be proportional to speed. That gives us a behavior like F = kv - mg k is some negatively-valued number (because the retarding force is up and v is down, kv > 0) and it depends on the magnet and the surrounding material and geometry. I assume that will be the same for all magnets (we have a platform with magnets around the rim, tightly fitting inside the tube) Terminal speed means kv = mg, and if my magnet is 0.1 kg (tough to measure, since it would tend to stick to a scale and it's hard to manipulate) and we approximate g as 10 m/s^2, we get mg = 1 N My estimate of the speed was 0.5 m in 3s, so that's 0.167 m/s (assuming it hits terminal speed quickly), and k is then 6 N-s/m And now, adding mass should result in a faster speed, but that should scale linearly, at least over some range of values. So if you increase the mass by 10x (0.9 kg of load per 0.1 kg magnet), you get a speed of 1.67 m/s Jumping from 1m gives a landing speed of 4.4 m/s, so you can tolerate a load of 2.5 kg additional mass per magnet (4.4/0.167 = 2.6 and subtract 0.1 kg for the magnet) If you are jumping into a tube that's 0.4m in radius, the circumference is 2.5 m, and you could fit ~100 magnets around the rim of your disk. Which should support 250 kg of load. More if you use stronger magnets So this back-of-the-envelope model suggests this would work.
  7. 1 point
    It is quantitative. Feynman mentions this - it's having electron spins line up. That's pretty sloppy for someone with a physics background. Forces do not require energy, work does. If there is no motion, or the motion is perpendicular to the force, no work is done. That's physics 101. Someone versed in quantum physics would know about the Heisenberg uncertainty principle, and the time constraints this places on conservation of energy
  8. 1 point
    Apologies to both of you. And molecules physically exist. A wave function is a mathematical description of a phenomenon. Not the phenomenon itself. (An electron has a wave function. The electron is not itself a wave function). You are asking something akin to what medium comprises a probability (which is one aspect of what a wave function describes). It makes no sense to ask the question. Wave functions and fields are related but still distinct concepts.
  9. 1 point
    @swansont scuddyx promised to answer me and has kept his word so please let the thread run at least a little longer. First let me say thank you for continuing the conversation and explain tha V represents the quantity etc under scrutiny for change. I know I labelled a time axis but I would like to consider the implications of not having a formal axis at all and then show that we can't do without it. This is quite different from an emergent phenomenon (as I understand the term) which arises as a result of specific and particular circumstances with a particular collection of objects. It cannot be linked to other phenoma taking place elsewhere (ie is independent of them). A good example is the action of an arch bridge. The massive strength of an arch bridge only occurs with a particular configuration of the arch stones and only when they are all there. The arch will not stand up, let alone support load, untill all parts are in place. If one is removed or missing the arch will collapse. A variation on this which shows that the remarkable emergent phenomenon is the fact that the shape causes the apllied force to be diverted through exactly one right angle is the ring. Load a part ring radially and it will bend. Apply that same load to a complete ring and the radial force will be turned into a circumferential one. To return to my diagrams. Say we repeatedly sample the variable under scrutiny, V. When change occurs we expect continuity in V. That is there is always some value for V (including zero) and there is never a sample for which there is no value. There are no gaps in the continuum, and every value is distinct and different so V1 is different from V2 is different from V3 (although it may be the same as V1) Now my plots show how we can distinguish V1, V2 and V3 using the second property I mentioned, that of order. If V1 = V3 but not V2 we have two changes using the order V1 V2 V3 but only one change using the order V1 V3 V2. So our running variable distinguished this difference. Consider a 50kg lump of Uranium slowly degrading through fission. V1 = 50kg V2 = slightly less than 50 kg because of radioactive decay. V3 = slighly less again. and so on But if all this decay occured together as one big change, not as a lot of small ones we would have a nuclear explosion instead of a slowly degrading lump.
  10. 1 point
    All particles can be described via wavefunctions the Schrodinger equations can be time dependent and time independent so time symmetry relations would certainly be involved. CPT involves time symmetry.
  11. 1 point
    A magnetic field is something you get when transforming an electric field into a moving frame. What we have here is similar to Feynman being asked to explain it to someone who lacked a physics background. He said something like ”I can’t explain it in terms you will understand” IOW there are concepts built on other concepts. In those cases, you need to understand the underlying material first. edit: the whole thing is good IMO (he talks of the difficulty of answering "why" questions and the necessity of having some things be understood) but the part I was referencing starts at 6:00, and he touches upon it multiple times
  12. 1 point
    Not necessarily. It depends on the quality of those dissenting voices or, more accurately, the quality of the evidence and analysis in those dissenting papers. Obviously, it may not be easy for a layman to make that judgement. And, of course, not all of the papers which support climate change are necessarily of high quality. And it may be that some of the 2.9% are actually pointing out problems in flawed papers in the 97% (which is a good thing). As swansont says, there are serious physicists who think relativity is wrong (and biologists who think evolution is wrong). That doesn't mean there is "another side" that is worth considering. Those people are just wrong. But it is good that there are people challenging the consensus. Science needs that. Einstein's views on quantum theory were wrong. But the fact that he challenged it made people think more carefully about those issues and come up with better experimental tests to confirm the theory. I don't think that is fair. None of those things have happened to the OP or to you for asking questions (unless I missed it).
  13. 1 point
    Electromagnetism is rather well understood* within mainstream science at this time. Scientists have developed reliable models that predicts a large range of phenomenons. Engineers have applied the models resulting in a large amount of applications. You have joined a good forum to enhance your understanding. Members here will be happy to provide sources or descriptions at various levels of details. Just ask questions! Sorry, no. I prefer other sources.
  14. -1 points
    I have seen that video a few times, and thanks for your respectful answer (unlike another staff member🙄) . And yes I never said I did not have a Physics background... I've been doing physics most of my life, Its my passion and understanding magnetism is also my aspiration. I do understand what Feynman is saying but in this case I do know about the current theories about magnetism, but I am questioning them because they are simply illogical. There are a lot of ways to describe the phenomena but there is one question to which I still haven't received an answer to. A magnet before it becomes a magnet is not a magnet.. its just a piece of iron boron, ceramic etc. its been seen that the quantitative nature of a magnet before it becomes a magnet is identical to after it becomes a magnet, so if the change is not quantitative then it has to be qualitative, so what is the qualitative attribute of a magnet? because it isn't quantitative! Feynman also says "there are electrical forces, gravitational forces, magnetic forces" forces require energy and frequency gives rise to energy. Current science, quantum physics in general has a lot of definitions for things, they say the magnetic force is due to an exchange of "virtual photons". Quoting: "electrostatic and magnetic fields involve the exchange of "virtual" photons instead, very close to an electron is a cloud of virtual photons which are consistently being emitted and re-absorbed by an electron". That is a deeper explanation to the "magnetism is caused by the motion of electric charges". This is also contradictory because "virtual photons or virtual particles supposedly pop in and out of existence, but this also violates the law of conservation of energy! This just goes into loops and loops! I still don't have an answer from anyone, except from the guy on the video, which seems to know what he talks about and makes more sense. Thanks for your time!
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