Is there a maximum speed beyond which we cannot travel and remain alive? A point at which a fore-shortened body and brain (in the direction of travel) will not be able to function, a speed at which the chemical reactions necessary for life cannot take place?
No, I think you are talking about acceleration rather than speed. At constant speed you might as well be standing still.
I think the maximum g's experienced by a living human was 20...during catapult from a Mig plane. But thats a bit of a myth, more plausible is 8 g's
You're forgetting the whole essence of relativity. To you in your spaceship, it appears that the universe outside is moving and experiencing the foreshortening. From your point of view you are standing still and everything in your ship is the right length.
people used to be afraid of the train because they thought that it's excessive speed would surely have detrimental effects on the health of the passenger. And it sure does when the train hits a massive object with no speed or opposite speed. The resulting deceleration (form of acceleration) causes havoc.
I am not talking acceleration. As Fraggle Rocker points out, there is a foreshortening at relativistic speeds. As you start travelling at a noticeable fraction of light speed, you will shorten in the direction of travel (though to you, all will seem normal it is said). I believe that the energy is decreasing as it is crushed against the light barrier. Example. If you are travelling at half light speed and you shine a torch in the direction of travel, even though the beam is moving at light speed, it is effectively moving at only half light speed in comparison to the torch and you. Chemical reactions and even the electrical energy necessary to life will move at a slower rate, having less energy. At some speed they will not be sufficient to work and at that point, we will die.
As Fraggle (and I) pointed out traveling at any constant speed is no different from standing still to the person traveling. Unless they are moving through some sort of medium without protection of course, but that's not what you mean I think.
as I tried to show with the train example, you can't know for sure till you try. Physicists are renowned for knowing shit about real life. Hence they might construct a spaceship capable of traveling faster than light (well, engineers would construct it), but do they know shit about whether you could survive the trip? no.
Such a particle is not known to exist. I fail to see what sort of process would make the difference.. :shrug: