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Indeed this is correct. Photons can travel distances greater than the radius of the observable universe without interacting with matter. This has been true ever since the period know as "recombination" when electrons became bound to hydrogen and helium nuclei. Prior to that time there were lots of free electrons that could interact with light. ...


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No extraterrestrial life has ever been found and we only know of one creature that has formed a civilisation: Homo sapiens. And we have not yet reached type I. So we know nothing from observations about civilisations that are beyond our own. Kardashev wanted to have a way of thinking that didn't put "humans" at the top, so he described types I, II ...


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I assume that the diagram indicates what the observer sees (if they had a big enough telescope!). i.e. The viewpoint is nearly in the orbital plane but not quite. Why then are the eclipses asymmetric, with the secondary eclipse being shallower than the primary? Well probably because the surface brightness of the two stars is different - i.e. they have ...


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Your intuition is correct - a moving source emitting wavefronts periodically will be closer to the previously emitted wave in the direction of motion, and farther from the previously emitted wave in the opposite direction - see the simulation here. You are also correct that the size of the effect depends on the speed of the observer relative to the speed of ...


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