I must confess a secret: I am a time-traveler. I know! “Who would have thought!” you exclaim. Hang with me, though, and I’ll elaborate.
First off, for all my “Mad-man-in-a-Blue-Box” friends, calm down. No vanishing blue box here, sad to say. No, the source of my time-traveling is a bit more mundane but no less imaginative. It is….
[Insert dramatic music here!]
Wait! Don’t run! Hear me out.
Follow along with me and you’ll see where I’m going with this. Or, coming from with this. Bopping along the time-stream can get a bit confusing. It’s a wibbly-wobbly-timey-wimey thing, you know.
Look up at the night sky sometime. See all those twinkling lights above you? (No, not the airplane on final approach, the ones beyond those twinkling lights.) Yes, the stars. Galaxies, and so on shining down on you. That’s where we are headed. As Douglas Adams pointed out:
“Space is big. You just won’t believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it’s a long way down the road to the chemist’s, but that’s just peanuts to space.”
The universe is approximately 13.77 billion years old. (I can show you the math, if you want, but it’s really boring.) And spacetime has been expanding the whole time. That means a lot of miles are out there. Space is so mind-bogglingly big that we can’t even use our customary terrestrial measuring systems to map it. Hence, the light-year.
Keep in mind that the light-year is not a measurement of time, it’s one of distance: how far light travels in one Earth-year. And that number is 2.998×108 m/s. That’s 299,800,000 meters every second. Or, approximately 185,103 miles every second. Every second.
Now, I can hear you asking: “Where does this tie into all of this time-travel blather, O Wise One?” Good question, Grasshopper! Follow along the time-stream….
Our nearest neighboring star is approximately 4.3 light-years away. (Other than our own Sun, that is. That star is 900,000,000 miles away, but we’re looking outside the neighborhood.) When you look up at the night sky at this little twinkling gem, the light hitting your retina left that star approximately 4.3 years ago. Think about it: You are not seeing that star as it is this moment, you are seeing it as it was 4.3 years ago. For an instant, you have stepped back in time. Want to travel farther back in time? Just switch your eyes to another target. How about the Andromeda Galaxy (also known as M31 to us astronomy geeks)? This little gem of the night sky is 2.5 million light-years from Earth. Looking at this beauty will take you instantly back in time to 2.5 million years ago. If the Andromeda Galaxy were to suddenly wink out of existence this instant, as you are reading these words, we would not know about it for another 2.5 million years. Isn’t time-travel, I mean, astronomy, neat?
The farther we look away from our world, the farther back in time we go. The Hubble Space Telescope performed an Ultra Deep Field survey recently and detected what is probably the oldest object yet seen: a proto-galaxy at a point in time that was approximately 480 million years after the Big Bang. That’s over 13 billion years ago. How’s that for time travel?
So, the next time you look up at the night sky, remember that you are a time-traveler. And you didn’t even have to leave your backyard to do so.