On Sat, Jun 07, 2025 at 06:14:55PM +0800, Bret Busby wrote: > According to the Doppler theory (I believe it was - this is from some > decades ago), if you would be travelling toward a set of traffic lights, at > the speed of light,
You could not reach the speed of light > and the traffic lights were red, the Doppler effect would cause them to > appear green, and, so you could travel through them; and, if you hit > anything, it would not matter, because, at the speed of light, you would have > infinite mass, as you would have a very large mass [ as you speed up your mass increases ] thus needing huge energy to reach close to the speed of light. The only way of travelling at the speed of light is to be a light beam in the first place. But yes: the Doppler effect would work. Astronomers see this a lot but the other way round: green is seen as red - because distant objects are travelling away from us; this is how they deduce that the universe is expanding: https://en.wikipedia.org/wiki/Redshift > it is like the question of "the universe" - it is said to be constantly > expanding and contracting - if that is correct, then, something must exist > outside the border of "the universe". If that is correct, then, how can what > we regard as "the universe", be regarded as a universe, when it is not all > encompassing? Not necessarily: if the universe bends back on itself (in a 4th spatial dimension) then it does not have an edge, in the same way that the surface of a balloon does not have an edge (the 2D surface is curved in the 3rd dimension): pump more air into the balloon and the surface expands. -- Alain Williams Linux/GNU Consultant - Mail systems, Web sites, Networking, Programmer, IT Lecturer. +44 (0) 787 668 0256 https://www.phcomp.co.uk/ Parliament Hill Computers. Registration Information: https://www.phcomp.co.uk/Contact.html #include <std_disclaimer.h>
