You know how in Star Wars Han Solo, Luke Skywalker, Chewbacca and the gang would jump into the Millennium Falcon and fly “from one end of the galaxy to the other” (to quote Han Solo himself)? Yeah. A recent article from The Economist essentially explained why that’s impossible. Not impossible as in, “We can’t do it now but one day we might be able to!” but impossible as in, “It could never happen. Like, ever.”
The problem is simple. Space is big. So big that it is, quite literally, almost impossible for us to truly begin to envision it. So The Economist used a very powerful tool, one I eagerly share with my students whenever I can: the analogy.
Let’s talk about the vast size of the universe. The closest star to our own star (that’s the Sun, of course) is Proxima Centauri. (If you thought it was Alpha Centauri, then ha! I know something you don’t know! Thanks, Google!) The Sun is 149,600,000 km from Earth, and Proxima Centauri–the next closest star–is 39,900,000,000,000 km from Earth. As you can see, using the exact, precise, mathematical distances isn’t actually that helpful, is it? I mean, you can see that Proxima is, like, way farther from us than our own Sun, but are you in awe? Probably not. Numbers can illuminate, but they can also obscure.
Okay, let’s try an analogy instead. Imagine that the Earth is a grain of sand sitting on the desk in your bedroom. The moon is another grain of sand right beside it. The Sun is a basketball (that’s roughly in scale, if you can believe it) and it’s outside your bedroom, way down the hall, somewhere in your parents’ room. From the point of view of the grain of sand on your desk, getting there isn’t impossible, but wouldn’t be an easy task by any stretch of the imagination and probably wouldn’t even be worth attempting. So where’s Proxima Centauri?
Well, if the Earth and moon are grains of sand side-by-side on your desk, and if the Sun is a basketball way down the hallway in your parents’ room, Proxima Centauri is a basketball that’s somewhere in Russia. (Needless to say, if you happen to be reading this blog while sitting at your computer in Russia, this analogy loses some of its power. But if you are somewhere in Canada, the United States, or even western Europe, you get the point, I trust). Now, from the point of view of the grain of sand on your desk, getting to that distant basketball in your parents’ room is a pretty huge challenge, but it is conceivable. But getting to that basketball in Russia? It’s a distance so great that, from the point of view of the grain of sand, it’s hard to even imagine it, much less attempt it. We can at least imagine it, sort of. For example, the Voyager 1 spaceprobe is pretty fast. It travels 17 km per second. Per second! And it could reach Proxima Centauri—in 75,000 years. Can you even imagine 75,000 years? I can’t. Not in any meaningful way, anyway.
This is my slight variation of the analogy as presented in The Economist; read the article I linked to above for the original, slightly more mathematically precise analogy. Read the article just because it’s absolutely fascinating reading. At the end, I took away three insights about education:
1. We are never travelling outside our solar system. (Okay, that isn’t exactly about education, but it’s still a pretty cool insight.)
2. It is the sacred duty of every teacher–regardless of subject or age level–to instill in his or her students a profound sense of awe at the world (and universe) around them. If you are a teacher, when was the last time you did this? When was the last time you even tried?
3. The analogy is a powerful tool. Like all powerful tools it can be just as harmful as helpful, and can obscure facts just as easily as illuminate them. Students need to learn the uses and limitations of analogies, and they need to see how they are used in a wide range of disciplines, not just in literature or fiction. Because they *are* used all the time in science, history, and politics, to name but three areas.
In closing, let’s return to the analogy for a moment. How hard would it be, exactly, for some people from your grain of sand to get into a little space ship and zip down the hall to the basketball in your parents’ room?
If you want to watch a remarkable science-fiction film–one of the best ever made, I would argue–that attempts to deal seriously with the logistics of a manned spaceflight to the sun, watch Danny Boyle’s astonishing 2007 film Sunshine.
One powerful insight this film will give you is that even getting human beings from the Earth to the Sun is a task so complex it doesn’t bear thinking about too much. And Proxima Centauri?
It would be easier to walk to Russia–ocean included.