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Everything posted by swansont

  1. The question of what happens when waves combine us a general one; there are multiple kinds of waves. The example in the video is more specific, as it has to do with the waves of the Schrödinger equation, which describe the probability of finding the electron at a particular place (and other things)
  2. A necessary but insufficient requirement. Your power station will go broke. And I can’t believe this has to be explained to you.
  3. “net production of heat” is not the same as “net production of energy”
  4. So it’s essentially gone in a few weeks, creating Tl -203, which is stable. Not a pollutant Where are the 14 MeV neutrons coming from? But 203 isn’t a pollutant, since it decays rapidly. 206 is stable. Why would it need to be removed? Emitted from what?
  5. ! Moderator Note From rule 2.7 “members should be able to participate in the discussion without clicking any links or watching any videos.” As I said, a link is insufficient You can put the information in a new post, rather than editing the original
  6. Having an infinite number of universes does not equate to all things being possible.
  7. ! Moderator Note Rules require that you post the details you want to discuss. A link is insufficient.
  8. I’m a physicist, so I’m in the minority of people who don’t complain about having to learn math (no “I’ll never use this!”) and I have used algebra quite often, as well as calculus, differential equations, trigonometry, etc. - basically all the areas of math I learned in high school and college. I learned about Benford’s law about 20 years ago, and have never had occasion to apply it. It’s neat, and there might be a few students who would be interested to learn of it. What is the audience who should learn about this in high school? I can only think it would be a thin slice of the student population, at best.
  9. swansont


    QM is a bit weird Spin 1/2 means the particle has a component of angular momentum (typically taken as the z-component) of 1/2 h-bar
  10. https://www.nature.com/articles/nature16155 Paywalled, unfortunately
  11. It is hypothesized that if you can reduce the energy of the vacuum with the Casimir effect, you could speed up photons by a tiny amount. Not a big enough effect to measure. https://en.wikipedia.org/wiki/Scharnhorst_effect A photon traveling between two plates that are 1 micrometer apart would increase the photon's speed by only about one part in 1036.
  12. No, not as far as I know. You have high-energy photons creating particle-antiparticle pairs, so there would be matter around for the photons to interact with. "Photon's past" from whose perspective? Surely not the photon's — no valid frame of reference there. Massive particles were created by photons (the pair production mentioned above) and photons could scatter off of those massive particles. The CMB is consistent with the photon creation from the recombination era - when the universe became transparent, tells us that photons were scattering before that. Is there a photon out there that never scattered? Possibly. I don't know how to assess how unlikely that is, or if it could be detected if nothing happened to send it in our direction.
  13. The issue that never seems to get properly defined is what one means by freedom of speech. Case 1: where one is referring to a document such as a country's Constitution (or similar document), then it's a right that the people have to not have the government retaliate or otherwise interfere with speech. But other people mean it as the ability to say whatever they want (case 2), and some go beyond that to mean saying whatever they want without fear of repercussion (case 3) So when one says there is no freedom of speech on this forum, or on some other public forum, that's wrong on terms of case 1. This is not an arm of a government, so there there is freedom of speech in that regard. But such a right is not without limits. If considering case 2 and case 3, then no, there is not. This is a privately-run place, even if the door is (initially) open to all. There are rules (things we won't discuss), and also repercussions for what one says (there may be pushback if someone disagrees with what you say or how you say it)
  14. Can never interact? All photons can interact, AFAIK. This doesn't make sense. They are in the universe. I don't know of a scenario where this would be true.
  15. Yes. At first, I expect, it will be workers willing to undertake risk on some kind of extended deployment. Similar to deep-sea fishermen going off for weeks at a a time, or transcontinental shipping. But you'll hit a limit of how long they will do this without the kind of settlements you describe.
  16. I don't think one can justify that. It continues to propagate until it interacts. Yes, a lifetime can be assigned, as long as it's from an observer's frame of reference.
  17. What is the entropy for the system? And in the divisions?
  18. No, it's not trying to define what time is. It's simply a reality that to measure time you need a system with massive parts. We don't have physics that predicts time from the perspective of a photon. You need to detect the photons somehow. They have to interact in some way. And you have to generate the photons. Clocks use photons, but not exclusively photons.
  19. I think the first step after government test-runs will be economic exploitation, should that ever become cost-effective. Only after that would any large-scale settlements work.
  20. Aren't those overlapping issues? What options do we run out of that's not related to overpopulation?
  21. Italy is an interesting example. I don't know if they typically venture outside of the Mediterranean. It's big, but Italy is almost in the middle. Makes sense their carriers would be designed to support STOL and helicopters; anything with longer range could be launched from the mainland, if their concern is the Med.
  22. It's not stupid, it's a matter of not having been exposed to the ideas yet. You learned something, which is a positive.
  23. Quantum physics tells us a vacuum is not nothingness.
  24. Sure. I think you could have quasi-permanent bases like that (more structurally sound, though), but you would have to remain indoors or be in a suit outdoors, like in the movie. If the choice is between terraforming and a generational ship and we have 100 years, then I think we're toast. If it's a choice between living on a spaceship and living on another planet or moon, I think the planet option is easier to achieve. (Power and dealing with gravity wells/orbits are two main reasons why)
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