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  1. As a none native speaker i had to look up 'parsimonious'. Not very flattering... But ok, in this case it more or less fits me: I did not know there was a distinction between closed and isolated, so thank you for the free education. With the thought experiment i proposed i think closed-system is still appropriate though: energy created from 'nothing', will actually be supplied by the negative energy of the expanding gravitational field originating from the created energy. Here you have the chicken and egg problem... 😁 This seem to be the thing: my simple thought experiment is not so
  2. I don't know what "time translation symmetry" means. I'll look it up. Thanks. That said, i thought that conservation laws applied to closed systems in the widest meaning possible. But note that a closed system is a pure hypothetical construct: e.g. anything accelerating within a closed system will cause gravitational waves leaking out of the 'closed' system. Perhaps it's the same for me not understanding your comment? Bit confused here. What has a single point mass in an empty universe to do with, eh, with what? Looks like kind of a philosophical question to me: in that case the
  3. I just mean (for as far as i know) that all energy gravitates: It doesn't matter whether it is stored as mass (e=mc^2) or not.
  4. Some years ago i reasoned that the gravitational field must have a negative energy content. Apparently that was not a very original though. I was also speculating whether the total energy (gravitational energy + the mass_energy it originates from) would be negative, equal to zero, or positive. My guess was that it must zero but i did not know how to make a logic argument for that, let alone make calculation with that. The best answer that i could find was that is was arbitrary, but lately i stumbled upon a lecture of Lawrence Krauss in which he also reasons that the total energy must be zero
  5. I know. Those are known factors but are not the whole story. Different species can also evolve in the same habitat. E.g. i can imagine that adaption A gives an advantage and adaption B give a different advantage, but the mix gives a disadvantage relative to A or B separate. Genetic incompatibility is than also an advantage. Perhaps not for the individual but for the new species it is.
  6. I think encryption would complicate making sense of things, but it would not make detection impossible. The mentioned broadband spread-spectrum techniques would complicate detection and making sense of things. The nail on the coffin is that i think that each generation of wireless communication is lower-power and relying on a finer grid. Also, the frequency is increasing by which absorbption in the atmosphere is increasing. The spillover radiation would simply be too weak to be distinguish from background noise. All we can detect is a very strong directional signal send by a civilizatio
  7. I wonder if this can be explained by the species not sharing a habitat: then there is no evolutionary pressure for genetic incompatibility as a species advantage. The generic compatibility is then only very unlikely.
  8. I am impressed by the effort you put into this. Especially the way you drive the piezo stack can make a huge difference to the simplistic way Woodward is doing this. However, having followed Woodward's efforts for about 25 years (yes really!), i am also a bit skeptical about the results: Woodward manages to only show about 5 to 20 micro newton, and even that is highly debatable because of measurement problems. Vibrations, temperature differences, electric and magnetic fields, etc can very easy give false signals. So i would advice to keep on the good work but also to be very s
  9. Very cool. It is now more than three years later. Do you have new results that confirm or contradict this?
  10. Indeed, it is completely irrelevant. I only mentioned this to show that it is possible to nullify the difference in start of acceleration for both observers by positioning the rocket motor between both observers instead of one at the level of the motor and the other one a some distance.
  11. I don't think that is relevant, because that can be compensated for by a mechanic construction (e.g. with the rocker motor is positioned in the middle of the rocket). But for the sake of the argument lets assume the rocket stays in the back, what would that entail? Let's see: The difference in start and stop is given by a constant time: For a complete rigid rocket this only depending the height: delta_t = h/c where: h: height difference between observers c : speed of light. The top observer will start later, but also stop later. The result is that it is 'pu
  12. Sorry to be absent for some time. They don't have to climb: the rocket just has to stop accelerating. That is the whole thing. for instance, when the rocket stops accelerating half-way the trip, then turns around and starts accelerating again. Then stops accelerating when the velocity is zero relative to the starting point. The observers will disagree on the trip-time! I think that is just weird.
  13. I realized this last night myself as well: the proper local acceleration depends on the 'height' within the rocket because the observed differences in speed of time. It even does explain the contradiction i started with: the travelers will experience different travel-time although traveling the same. I think i just have to accept relativity produces weird effects. 🤪
  14. i know it is accurate, but in this case it is not relevant. I you want to go into technical details: the deformation can also be compensated for with actuators so the rod will act as completely rigid up to measurement precision.
  15. Correct. I can be wrong, but i think not this one. If so, please show me how.
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