I got thinking about traveling at light speed the other day while I was eating breakfast. There must have been something in my Shredded Wheat and Bran that stimulated intense neural activity, because all morning at work I felt like my mind was bubbling over with interesting and stimulating thoughts and concepts. As I pondered the eventual possibility of interstellar travel (or even intergalactic travel) a few thoughts crossed my mind:
Regardless of mechanical capabilities (we all know the Falcon could never truly endure light speed) could a human being actually survive travel at light speed? I can’t see any reason why they couldn’t exist quite happily while traveling at that speed – after all, we travel at 800 km/h with basically no sensation of it in airplanes – but could a person actually accelerate to 300,000,000 m/s in the course of their lifetime? How long would it take, and what force would have to be applied against them in order to maintain the level of acceleration required to get them there? Traveling at light speed would potentially be cool, but not if you were a cold, rotting, corpse because you died during the approach. Even if you did survive the force of acceleration, you wouldn’t want to end up with permanent damage or a facial expression stuck like the middle one below:
The problem with accelerating quickly to very high speeds is mainly that doing so impedes circulation, as far as I can tell. Your heart is designed to pump blood around your body at or near atmospheric pressure. When a substantial amount of force is applied against your body (or by your body against something else, same thing!) – as in the case of a vehicle collision, airplane crash, Gravitron-gone-wild or willful subjection to interstellar travel – your heart may not actually be able to pump blood hard enough to overcome the applied force. Basically, your blood ends up pooling in the direction of the applied force instead of circulating and keeping your tissues (and thus, you) alive.
Acceleration is often described as a multiple of the rate of acceleration due to gravity (the “G force”: ~9.8 m/s^2). Plenty of studies/events have demonstrated the detrimental effects of sustained (or even brief) exposure to high G’s (greater than 5 or so). High-velocity jet pilots and other maniacs wear special equipment and train their bodies to cope with forces upwards of 9 G’s, but only very briefly (seconds). They need to flex certain muscles throughout their bodies in order to manually “encourage” circulation; as a side note, muscle flexing is actually always a component of healthy circulation, even at STP. Particularly without this kind of training or special conditions, prolonged exposure to high G’s would almost definitely lead to rapid loss of consciousness. In a way, it’s comforting to know that many people who die in tragedies like SwissAir 111 may have passed out from the intense G force prior to being decimated by the impact.
Anyway, based on the Wikipedia article on G force I decided to see how long it would take to accelerate to light speed at a couple of different (possibly) tolerable G forces. I pulled out a pad of paper and started scrawling down some formulas from intro physics. Formulas 1 and 2 were used to find the time required, based on average acceleration (about 5.5 g’s, or 55 m/s^2 first) and initial and final velocities (0 m/s and 300,000,000 m/s, respectively).
I was actually surprised to find out that at about 5.5 G’s it would only take 63 days to make it from 0 to light speed. Since 5.5 G’s is probably right around the threshold of maintaining consciousness, this would probably be the most horrendous experience of your life. 63 days of being pressed back against your seat so hard that you’re constantly bordering on passing out, probably unable to eat anything since even IV fluid might not be able to circulate due to the force against it. [One possible, futuristically awesome solution to this that my colleague Emma and I came up with would be micro-pumps inserted into the blood vessels throughout your body, similar to stints.]
If you slow the rate of acceleration down to 3 g’s, it would probably still be absolutely terrible for a prolonged period of time (similar force to what you might experience on the Gravitron, which recommends no more than 80 seconds of exposure), and it would take 118 grueling days. Plus, remember that you need to double this number since you’d have to decelerate upon arrival. You’re looking at the better part of a year in a state of constant pressure…
Anyway, I’ve exhausted my interest (and probably yours) in this subject by now, so I’ll leave it at that. Feel free to carry on with my calculations and find the amount of time you’d be willing to travel to reach light speed, and the G’s you’d be willing to withstand. What do you think? Sound like a good time?