I've been watching the Cosmos again with my soft-spoken and funky cool friend, Carl Sagan. If you've never seen Cosmos, stop what you're doing right now and watch it immediately. I'll be here 13 hours from now when you get back. Having just watched the mind-bending episode on space travel and its relationship to time, I felt compelled to ponder the endless possibilities.
The concept of deep-space travel seems to be intrinsically compelling to us wee humans. Maybe it's the prospect of new and unknown worlds. Maybe it's because we like to go fast. Or maybe, like George Mallory famously declared when asked why he wanted to climb Mount Everest, we want to explore the universe "because it's there." Regardless of the reasoning, there's no denying that the idea of space travel is pretty wicked awesome. UNANTICIPATED PESSIMISM: That's what makes it so unfortunate that the barriers to realizing this potential are so great.
The fundamental problem of deep-space travel is special relativity. Thanks, Einstein. OVERSIMPLIFICATION: In my never-having-taken-a-physics-class layman's understanding, special relativity basically states that all motion is relative, but that the speed of light (the c in E=mc2) is a constant against which all motion may be compared. Furthermore, nothing (except light, of course) can travel at the speed of light. You can travel at 99.999999% the speed of light, but you will never reach that asymptotic value.
Further complicating this whole situation is the fact that, as you approach closer and closer to the speed of light, weird stuff starts to happen. The wavelengths of light become either shorter or longer, meaning that everything coming toward you turns blue and everything moving away turns red. You get very skinny in the direction you're traveling. This is not a product of perception, mind you, you actually get physically skinnier.
The biggest problem that special relativity introduces to us, however, is that as you approach the speed of light, your mass becomes heavier and heavier. Why is this a problem? Because it means that you'll need exponentially more and more massive amounts of energy to sustain your speed as it increases. So where are we going to get this massive energy source? Not sure. Maybe nuclear fission. More likely nuclear fusion. Maybe some magical solution we haven't even conceived of yet.
SUDDEN DIGRESSION: Am I crazy, or do Carl Sagan, Neil Diamond, and Michigan State head football coach Mark Dantonio look like brothers? Cousins, at the very least.
CONTINUATION: So, okay. Let's just assume we find a magical power source that enables us to travel up to 99.9999% the speed of light. Woohoo! We did it! Let's break out the space colonies and Death Stars and blue-headed aliens, right? Well, not quite. Sorry, Han.
Somebody just told Han a parsec is a unit of distance, not time.
Remember that weird stuff that happens as you approach the speed of light? Well, the weirdest thing is a concept called time dilation. Essentially, if you travel fast enough, time slows down. Whu-whu-whu-whuuuuuut? That's right, folks. You actually age more slowly if you are traveling at the speed of light. Sounds great, right? The ultimate anti-aging cream. Yes and no. Say we could build a machine to take us to the center of the galaxy in only eight years ship time. In Earth time, we would be traveling for some time on the order of 30,000 years. The question at this point becomes the relative value of traveling through deep space, given the very real possibility that civilization as we know it would be long gone by the time of any potential return.
Is that it, then? Are we forever doomed to linger in this boring old solar system? (jk, Jupiter, keep doing what you're doing!) Not necessarily. So what is an alternative that might let us circumvent these apparently debilitating obstacles? Where do we go from here? Simple.
CLIFFHANGER: We go to the fourth dimension.
From the interstellar starship of Ivan Zissou
dictated but not read
cth
3 comments:
It is so hard to comment on your blog because there is so much great stuff to discuss! Loved this one. My absolute favorite topics. And thank you especially for bringing up Han and the parsec.
I hear you. I excuse Han myself because, as the esteemed Dr. Sagan tells us, we cannot look out into space without looking backward into time. Therefore, in terms of spacetime, any measure of distance can be construed as a measure of time as well. It's a stretch, I know, but I choose to believe Han Solo would never make such an error.
Well said!
Post a Comment