Actually, nothing can get to the speed of light
except light itself. If the man started off in a
spaceship, even if his rocket engines ran forever
and never ran out of fuel, the spaceship would
still never get up to the speed of
Here's what happens. As you get
close to the speed of light, your mass increases.
You know how it's much harder to push a bowling
ball than a marble? If a bowling ball was
traveling at 99.995% of the speed of light, it
would have as much mass as a (resting) car--and be
just as hard to push. So it becomes harder and
harder to accelerate. At 99.999999995% of the
speed of light, a bike would have more mass than a
(resting) freight train! So you can get closer
and closer to the speed of light, but as you do,
it gets harder and harder to go any faster.
There are other effects, too. As you get
close to the speed of light, time (for you) slows
down. Your watch may show only 1 minute has
passed, but back on Earth, a day has gone by. If
you could still see Earth through a telescope, it
would seem like everyone was moving around at
breakneck speeds. This was first explained by
Einstein in a theory we call relativity. It has
proved to be amazingly accurate. In fact, the
clocks on satellites run at a slightly "wrong"
speed (relative to Earth) unless they are
corrected for relativity.
The universe is a
very interesting place to live!
Even the very fastest spaceships are much, much,
much slower than the speed of light. Still, we can
wonder, what if we could make a spaceship that
could go that fast? The problem is that the closer
you get to the speed of light, the harder it will
be to go a little bit faster. To actually get to
the speed of light would take an infinite amount
of energy (that is to say it simply can't happen).
As far as we know, nothing in the universe can
travel faster than light, so we have no scientific
explanation for what would happen to a person if
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