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Everything posted by swansont

  1. ! Moderator Note Sorry, no, not good enough.
  2. It needs to be in equilibrium. This requires infinitesimal changes in whatever property, meaning an infinite number of steps. They each take a finite amount of time.
  3. Because you can’t actually be in equilibrium during the process and have it take a finite time
  4. If they have an equal magnitude, the shift from the velocity and the shift from the expansion should cancel if the object is moving toward us and far enough away that the expansion is occurring (i.e. gravity is not overriding it)
  5. Robots use could be because of physical danger from e.g. falling debris.
  6. Speak for yourself. This doesn't seem to be an impediment for others.
  7. AUDI R6 has been suspended 3 days for abusive comments and blatant trolling
  8. More like irrelevant. Didn't mean to imply it was intentional.
  9. ! Moderator Note Since this is essentially the same question, threads have been merged You add the vectors. It will accelerate in the direction of the resultant. The spacetime expansion comment is a red herring (or possibly blue herring if you are moving toward it quickly enough) since expansion will not overcome the intermolecular bonds
  10. I refer you to the response I gave some moments ago.
  11. Asserted without evidence. Can I combine electrostatics with mechanics? Coulomb's law says nothing about the motion of an object, yet I think I can describe the classical motion of a charged particle in proximity to another charged particle. I thought you knew all of physics.
  12. Why is this a requirement? Asserted without evidence.
  13. I thought you knew all physics?
  14. Why what? reversible means dS = 0 https://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node48.html https://en.wikipedia.org/wiki/Second_law_of_thermodynamics#Derivation_of_the_entropy_change_for_reversible_processes
  15. You were also given thermal noise.
  16. What does one have to do with the other? (physician = medical doctor)
  17. Reversible processes and the second law are closely intertwined. You must have reversible processes to keep entropy constant, and they don't exist (for any system where you would be applying thermodynamics, at least). Thus, with entropy increasing, perpetual motion is impossible.
  18. There's no way that advanced life could have existed for the first several billion years of the universe, and arguably could not have happened for a few billion beyond that. That says nothing about the attenuation by the interstellar medium. Again, this would only mean that the signal carries a little further, and if a weak signal is essentially gone after a LY (your contention) then a stronger one is gone after 2 or 3. Which makes zero difference. You didn't say concentrated effort. You said we don't do it. Drones are not cars, and don't operate in the same complex environment. Are any vehicles which drive in traffic doing so in anything other than a test program (typically with a driver on hand for when it fails)? I keep reading about them hitting pedestrians. Also how you can trap them
  19. I don’t believe the math work out for that. 50k LY in radius and 1000 LY thick is a volume of less than 10^13 cubic LY. A million civilizations means they require a volume of less than 10^7 cLY, or a radius of ~200 LY (assuming equal spacing for max separation) So a million civilizations could not all be thousands of LY apart. For any one that is that isolated, many others have to be much closer. They don’t have to come here, we just need to be able to detect them. So these are impediments for them colonizing but somehow not for us? And now world building is in the inevitable march of technology? Citation needed. We seem to be able to do radio astronomy. The interstellar medium doesn’t filter those signal, often over much, much greater distances (and attenuation is an exponential) What makes military radar immune to “fizzling out”? We don’t? https://en.m.wikipedia.org/wiki/Arecibo_message Not really. They are not reliably autonomous.
  20. A condition of the question was that no new physics is required.
  21. I guess you must be in the "there are no aliens" camp, too, seeing as there are no actual barriers to interstellar space travel, and your answer to the OP sounds like it's "no, space is not too big". If not, where are they?
  22. On the contrary. Technology marches on and I'm in that parade. I've been doing R&D for >25 years. Not requiring new physics is an insufficient answer. I've witnessed firsthand that every time you try to get an incremental improvement that some new problem crops up, usually something unanticipated, that needs to be solved. There are theoretical limits to everything, even if you aren't aware of them. "technology marches on" is a slogan, not science. It's not even a guarantee. We've been "50 years away" from fusion for ... 50 years. Flying cars are not ubiquitous — and for good reasons, that people didn't seem to discuss back in the day, and reminiscent of the arc of this thread. There's no new physics required for them (either of them), after all.
  23. Wow. No science at all. Dolphins are intelligent. Why haven't they launched any space probes? They even breathe air. Why haven't they launched probes to explore land here on earth?
  24. So it sounds like you're basically arguing the opposite of what I am. That it's trivially easy to move through interstellar space and visit other stars, so the only reason we haven't had visitors is that they don't exist. OK, make your case.