Re: Can we 'see' the Earth's past?

Brandon,

Yes, if we could somehow travel faster than light, we could see the Earth's
past. This is why physicists often say that "faster-than-light" travel
is equivalent to time travel.

To see why we need to go faster than light, imagine that we leave Earth in a
spaceship, say on a Tuesday. If we go, say, half the speed of light, the light
from the Earth will catch up to us. So after we've traveled for one day, the 
light leaving the Earth on Wednesday will already be next to us. Clearly this
will not help us see the past, so we have to go faster than the speed of light.
But relativity theory tells us it's not possible to go faster than light,
and time travel leads to all sorts of paradoxes, so most physicists think it's
not physically possible anyway.

There is a minor technological problem in "seeing the Earth's past" - the fact
that, once we got far enough away to see the 65-million-year-old light, there
wouldn't be enough light for us to see any details of what was happening on the
Earth! NASA is talking about trying to make maps of planets around nearby stars,
and even that is a HUGE technical challenge. But of course, surviving a trip
through a wormhole would also be a huge challenge! These things are fun to think
about, though.

Pauline