Back in time to the Big Bang (cont.)
Tim I thought you wanted
to take me in your time machine?
Ellen Tim, this is a time machine.
Tim Why? It only makes the stars and the galaxies appear bigger.
Ellen Yes. But think - when do you see the stars and the galaxies?
Tim Now, of course.
Ellen Only if light traveled with infinite speed- but it does not.
The speed of light is 300,000 km per second, but in space all distances
are enormous. It takes light about 4 years to cross the space to our neighboring
star.
Tim OK - but I still don't get your point about the time machine.
Ellen Looking into space is like looking back into the past. The
deeper we look into space, the further we look back in time. The light
we see from a star on the other side of our galaxy was emitted about 100,000
years ago - when we were still sitting in caves and hurling clubs.
