Cancer Posted February 1, 2021 Report Share Posted February 1, 2021 Quote 2. Of the anomalistic year, the sidereal year, and the tropical year, which one is the longest? Sadistic astronomy questions suitable for hazing rituals, part N+1. Quote Link to comment Share on other sites More sharing options...
Bazza Posted February 1, 2021 Report Share Posted February 1, 2021 Is ‘change’ required for physics? Ergo, can you do physics without ‘change’? Quote Link to comment Share on other sites More sharing options...
Pariah Posted February 1, 2021 Author Report Share Posted February 1, 2021 Yes. It's called Statics. Quote Link to comment Share on other sites More sharing options...
Cancer Posted February 1, 2021 Report Share Posted February 1, 2021 Archimedes's Principle and hydrostatic pressure are such topics that I've taught just in the last month. Also, the observation that certain situations are stable (at least in some sense) can be profoundly important. In the late 19th Century, Rutherford's discovery that the atom had the positive nucleus (with nearly all the mass) in the middle and the electrons in a cloud around it. The picture of electrons in orbits around the nucleus was immediately obvious, but it brings in a terrible problem. To have orbits, the orbiting object is continuously accelerated (even if it's a circular orbit, the acceleration is towards the center so its direction changes even if the speed does not). But an implication of Maxwell's equations is that when you accelerate a charge, that produces some radiation, and some of the energy is lost in that form. (Synchrotron radiation is one label for this radiation.) But for electrons orbiting a nucleus, there is only a fixed amount of energy there, and if the electrons really are in orbit, then they should quickly (much less than a second) radiate all that energy away and the electrons spiral into the nucleus and stay there. Now, we observe that is not so: stable atoms exist for very long times. Therefore something else, unknown at the time, has to be in operation to make the electrons' "orbit" outside the nucleus stable. This led into the discovery of quantum mechanics and so on. Quote Link to comment Share on other sites More sharing options...
L. Marcus Posted February 1, 2021 Report Share Posted February 1, 2021 Rutherford had a lot to answer for. Quote Link to comment Share on other sites More sharing options...
Cancer Posted February 1, 2021 Report Share Posted February 1, 2021 But it took him, after being elevated to the peerage a decade or two later, to get the Admiralty to look at and fund work on sound echolocation for detecting U-boats back in WW1. Pariah 1 Quote Link to comment Share on other sites More sharing options...
Logan D. Hurricanes Posted February 4, 2021 Report Share Posted February 4, 2021 L. Marcus and Cancer 2 Quote Link to comment Share on other sites More sharing options...
Old Man Posted February 4, 2021 Report Share Posted February 4, 2021 Wolf has covid, first pig refused to wear a mask, second pig wore one but didn't keep it over his nose. Third pig had a gun. 'Murica! Logan D. Hurricanes 1 Quote Link to comment Share on other sites More sharing options...
Old Man Posted February 5, 2021 Report Share Posted February 5, 2021 Quote Link to comment Share on other sites More sharing options...
Bazza Posted February 6, 2021 Report Share Posted February 6, 2021 i = sqrt(-1) Quote Link to comment Share on other sites More sharing options...
Cancer Posted February 6, 2021 Report Share Posted February 6, 2021 yup. Quote Link to comment Share on other sites More sharing options...
Pariah Posted February 6, 2021 Author Report Share Posted February 6, 2021 Finally, a real conversation in this thread. Cancer 1 Quote Link to comment Share on other sites More sharing options...
Starlord Posted February 6, 2021 Report Share Posted February 6, 2021 Science shows the more substantive conversations you have the happier you'll be. Quote Link to comment Share on other sites More sharing options...
Bazza Posted February 6, 2021 Report Share Posted February 6, 2021 Yep, 😁. They must be using that word ironically. Quote Link to comment Share on other sites More sharing options...
Logan D. Hurricanes Posted February 6, 2021 Report Share Posted February 6, 2021 11 hours ago, Bazza said: i = sqrt(-1) I squirt...? Quote Link to comment Share on other sites More sharing options...
Bazza Posted February 6, 2021 Report Share Posted February 6, 2021 It is an imaginary number. The scientists can explain it. Quote Link to comment Share on other sites More sharing options...
Cancer Posted February 6, 2021 Report Share Posted February 6, 2021 Mathematicians. I just use it. Quote Link to comment Share on other sites More sharing options...
Pariah Posted February 6, 2021 Author Report Share Posted February 6, 2021 I learned about the concept of imaginary numbers in Algebra I, probably my freshman year of high school. I actually used imaginary numbers my final year as an undergraduate, in quantum mechanics. Quote Link to comment Share on other sites More sharing options...
Bazza Posted February 7, 2021 Report Share Posted February 7, 2021 Are ‘imaginary numbers’ real? Quote Link to comment Share on other sites More sharing options...
Pariah Posted February 7, 2021 Author Report Share Posted February 7, 2021 Strangely enough, yes. There are certain things you cannot do in electronics without the use of imaginary numbers. Quote Link to comment Share on other sites More sharing options...
Bazza Posted February 7, 2021 Report Share Posted February 7, 2021 Next question. Are they a higher form of mathematics? Quote Link to comment Share on other sites More sharing options...
Cancer Posted February 7, 2021 Report Share Posted February 7, 2021 "Higher"? Not sure about that. They mesh fairly simply within algebra and calculus. Higher than what? Quote Link to comment Share on other sites More sharing options...
Bazza Posted February 7, 2021 Report Share Posted February 7, 2021 Higher than real mathematics. Quote Link to comment Share on other sites More sharing options...
Starlord Posted February 7, 2021 Report Share Posted February 7, 2021 Eleventyseven. There...that was easy. Quote Link to comment Share on other sites More sharing options...
Ternaugh Posted February 7, 2021 Report Share Posted February 7, 2021 24 minutes ago, Bazza said: Higher than real mathematics. The set of all imaginary numbers has cardinality with the set of all real numbers. The proof is left as an exercise for the readers. Cancer 1 Quote Link to comment Share on other sites More sharing options...
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