The Explainer General
Einstein established a new approach to science: Relativity, in which the mass and speed of objects are stable only in relation to their surroundings. One inescapable part of relativity is that space and time are parts of the same fabric. Very big masses and very fast speeds can warp that fabric.
One surprise discovery: there is a limit to how fast anything may travel. Anything approaching the speed of light requires more and more energy to push it only a little closer, until it can’t be pushed more. Unless we solve this problem, c (the symbol for the speed of light) is as fast as we’re going to get. But if you travel close to c, unusual things happen.
Two twins, Bill and Will, plan to make a fast trip to the nearest star, Alpha Centauri, on their twentieth birthday. The distance is about four light years away from Earth (light year = distance light travels in a vacuum in one year, about 5,865,696,000,000 miles). Will is stuck in a traffic jam and misses the blast off. Bill goes alone. He travels very close to the speed of light, .9999999 c, whips around Alpha Centauri and returns at the same speed. When he lands he asks for his brother Will.
Bill has been traveling for a bit over eight years; he’s 28 years old. But at this speed, his spaceship time has played out sloooooowly in relation to earth time. To Will on Earth, Bill’s trip took 49 years. Will is now 69 years old.
If the spaceship had traveled a little bit faster, say .9999999 c, Bill would still have aged 8 years. But when he returned to Earth, Will and everyone else he knew would be dead, since 155 years would have passed.
Recently, with fantastically accurate clocks, we’ve proved Einstein’s theories: astronauts traveling at thousands of miles an hour on space stations age a few seconds slower for every year of Earth-time.
Can we ever travel to distant stars? Not unless we find a way around Einstein’s shifting nature of space and time. Easy for Star Trek. So far, it’s impossible for us.
Jan Adkins is excited by things tiny and by enormous concepts. He’s published about forty-five books but they seem to be only excuses to find new stories and learn new facts. He’s been called “The Explainer General” because most of his work unsnarls complicated knots of confusion and re-builds them as simple paths to understanding. He explains bright bits of the world in pictures and words, often to young people. He’s written about sandcastles, bridges, pirates, knights, cowboys, maps, sailing, knots, coal, oil and gold. He’s got a long list of things he still wants to figure out and explain. Adkins (this is what his grandsons call him) believes real history and real science are ten or twelve times cooler than fairy tales and magic.
You know about Haley's comet, but did you know that another less famous comet is passing close to Earth right now? You will hear about it from Kerrie Hollihan tomorrow.