Yes! This is a consequence that few people realize or stop to consider, and is rarely addressed even in science fiction literature written by authors such as Asimov, Poul Anderson, etc., who are actually highly qualified, professional scientists and surely must realize this. In the Star Trek series, however, they make passing mention of or at least imply that their starships' deflector shields are needed and used, not just to defend against hostile attacks, but also just to protect them from severe damage and even destruction from high speed collisions with the matter that exists even in the highly rarified, nearly perfect vacuum of interstellar space as they move through it. This is yet another reason to doubt that UFOs are actually alien, interstellar spaceships (unless, of course, some kind of hyperdrive or warp drive precludes the necessity of having to move through ordinary space at high relativistic speeds).DrW wrote: ↑Tue Jun 29, 2021 5:52 pmPhysics Guy,
Thank you for your technical contributions to this discussion, especially for your earlier tutorial on some of the math and physics of relativistic travel. Relativity continues to delight.
Aside from the propulsion energy problem, there is another consequence of relativistic speed travel that I have not seen mentioned yet on this thread. That consequence is the fact that even in the vacuum of interstellar space, a near light speed spaceship would encounter enough gas and dust particles at high enough velocity that the collective energy of such collisions would eventually ablate or melt pretty much any available material. Ablation and melting are already a problem at 0.2c. https://iopscience.iop.org/article/10.3 ... 357/aa5da6
Many of the reports of flying saucers claim that they are spinning. One can imagine that constant rotation would distribute the craft/particle collision energy around the perimeter (constantly changing leading edge) of the craft reducing heating and ablation and thus increasing the speed that they could safely travel in space.
In one science fiction story I read by Arthur C. Clarke, colony ships powered by tapping nearly limitless zero-point energy and moving at high relativistic speeds protected themselves by pushing iceberg sized masses of ice ahead of themselves as ablative shields. In the story, one of these ships carrying a cargo of cryogenically frozen colonists was forced to make an unscheduled, emergency orbital stop at a previously colonized world to replace their too severely depleted or damaged ice shield. I forgot the name of the story. I think I read it long ago in Isaac Asimov's science fiction magazine.