Tripping the Light Fantastic

As you look at those stars on the night sky, you should always keep in mind that what you are seeing is what happened a long time ago. For hundreds, if not thousands of years, geniuses such as Einstein and Isaac Newton and even further back to ancient Greeks and Persians wondered about light. For a really long time, it was believed that light could travel at any speed through space because, in those days, before telescopes, ancient stargazers believed that there was nothing to block the light. So they thought it could speed up and slow down.

But now we know differently. Space is not as empty as everyone once believed and the speed of light is one of those amazing things that stays the same, no matter what. This is a good thing if you think about it for a second. Because light can be counted on to behave the same near earth as it does billions of miles away, we can make predictions about what to expect.

Consider this image, done to simulate exactly how fast light travels from the Earth to the Moon. It takes 1.25555 seconds. The light from the sun takes eight minutes to get to us.

I remember you telling me what you learned when you did that project on Einstein a couple of years back. You told me that light traveled 186,242.4 miles a second. How fast is that? Suppose you were shine a light from Bend to New York on the other side of the United States. That beam of light would travel back and forth 60 times in a second.

This galaxy is the farthest light has traveled, measured by Hubble at 13 billion light years away. The universe was only a billion years old when this galaxy (on the right) began to send its light out, so long ago, the earth wasn't even here yet. Because that is so fast, it is almost impossible to imagine. Look at your Mom across the room. What you are seeing is not what you think. It actually happened 20 billionth of second ago. Now imagine that our Milky Way is 100,000 light years across. In terms of galaxies, that's not very large. But it does require a very large imagination to try and picture that king of event.

This is the closest galaxy to us at 42,000 light years away.