An 8 Year Old’s Questions About Space Travel
Last night before we started reading in his bed, The Kid asked me out of the blue – as children often do – how fast light travels.
“186,282 miles in a second,” I answered.
“Some kid said that sound travels faster than light in space,” The Kid said.
“Sound can’t travel in space,” I answered. “But if it could, light is much faster.”
“In space, no one can hear you scream,” The Wife interjected. “By the way, which movie is that from?”
“Alien, I think,” I said.
Seeing the opportunity to spark the kid’s imagination I continued. “Nothing can travel faster than light.”
“Nothing?” The Kid said. “He paused. How about if you took ten or thirty rockets and put them altogether?”
“They still couldn’t travel anywhere near the speed of light. You see the problem is that the closer you get to the speed of light the more you need more and more fuel.” Technically not right, but how do you explain gaining mass – or even the concept of mass – to a child?
“How long did it take to get to the moon?” The Kid asked.
“Four days.”
“How far away is it?”
“About 250,000 miles. So that means that it takes light about 1 1/2 seconds to travel between the Earth and the Moon.”
I then did some quick calculations in my head. 4 days=350,000 seconds or so, divided by 1.5 = 225,000.
“So light is 225,000 times faster than our rockets.”
The Astronomy lesson continued. Has man ever been to deep space? No, but the machines we made have – if you consider “deep space” to mean beyond the outer planets. How about to a star? No, but we made machines that have orbited our Sun – which is a star. Have we gone to any other stars? No because the nearest is 4 light years away – and if our rockets are a quarter of a million times slower than light – then it would take us a million years to travel there.
Again, technically this is incorrect. Theoretically it would be possible to travel to the stars faster, but you have to tailor your answers to your audience, and what is important in this case is the sheer distances between the stars. Whether the journey took two hundred years or a million is immaterial to an 8 year old. Either number is huge.
His thoughts turned to the universe. Was it as big as infinity?
For all practical purposes yes, but according to current theory, it’s about 30 billion light years across, and still expanding.
“What would happen if we came to the edge of it?”
I couldn’t think of a good answer to that one. My instinct said that an edge was not possible, that we were like ants walking on the outside of a balloon and that eventually we would return to where we started. Kind of. However in the mean time the universe would continue expanding, so the point where we started really wasn’t the point where we started: “new points” now lay in between. Besides in order to arrive where we began we would have to travel faster than the expansion of the universe, which would mean we would have to travel faster than light which brings us to time travel – backwards in time, the universe collapsing like high speed film of a firecracker exploding, the pieces combining and reforming, the smoke and light being sucked back into the tightly rolled paper.
“I think it’s time for Harry Potter,” The Wife said.
“Yeah, read Harry Potter,” The Kid commanded.
Saved by J.K. Rowlings.
