While you’re enjoying your view of the Pacific during happy hour, here’s a deep thought to accompany those still waters: How old is the universe?
Uh, you’re asking me? A guy in a beach chair with chili stains on his shirt? I’m no scientist, so how the heck should I know?
Let’s turn to the scientists, then. They’ll tell you the universe is 13.8 billion years old.
Well, if nothing else, that’s a refreshingly user-friendly number. I mean, unlike some of the wacky-big numbers that are associated with things cosmological, 13.8 billion is something we can get our heads around.
For example, there are 7 billion people on earth now. Or, consider that Bill Gates is worth about $77 billion. Lots of other guys weigh in at over a billion bucks these days. So this billion scale isn’t the sole domain of scientists, since normal work-a-day people, such as accountants, bankers, analysts, and so on, deal with billions all the time.
But the number isn’t the real story. No, the story is the concept behind it. And for that we look back 90 years to an astronomer named Edwin Hubble.
You might recognize that name. It’s the “Hubble” that the famous space telescope is named for. The Hubble telescope is always making news for its cool discoveries.
Which is a fitting situation indeed, since Hubble himself was quite the news maker. Back in his days, the common outlook was that our hometown galaxy, the Milky Way, was, in itself, the entire universe. It was sort of like standing on Saipan in the dark and saying Saipan is the only island in the world. Those lights from Tinian? Must be from Saipan, since there’s only Saipan.
Telescopes had been around for hundreds of years. So there was no shortage of things observed, nor of people to observe them. But what they lacked was a sense of scale. Sure, they saw lots of stuff, but they had no idea how far away the stars, or groups of stars, were.
Worse yet, they didn’t have pizza delivery back then, so they had to pull these all-nighters subsisting on sardines and prunes.
In 1924, Hubble made history by reckoning some distances and by showing that some visible objects were, in fact, entirely separate galaxies. In other words, we’re not the only island.
And in 1929, Hubble announced that distant galaxies were moving away from earth, and, not only were they moving away, but that the farther away they were, the faster they were moving.
There’s a lot of juice in that statement. It means this: The universe is expanding.
Although neighboring galaxies might clump together based on their mutual gravitational attraction, the big picture is, plain and simple, one of galaxies moving apart.
We’re hot on the trail of this age thing, but it’s time for some human interest backstory.
Hubble’s distance calculations were rooted in an earlier discovery made by a lady from Massachusetts named Henrietta Swan Leavitt. Her efforts went largely unheralded, even though she is the one who provided the key used to open the cosmic lock. Ms. Leavitt passed away, at age 53, in 1921, a few years short of shy of Hubble hitting fame. Leavitt deserves fame, too, but she didn’t get it.
OK, let’s get back to the action. Where were we? Ah, yes, hot on the trail of this age caper. Let’s think in Hollywood terms: If we play the cosmic movie forwards, the galaxies get farther apart from each other as time goes by. We know this because of Hubble.
But what happens if we play the movie in reverse, thus looking backwards in time instead of forwards? Well, the galaxies will get closer and closer to each other as we go earlier and earlier in time. Eventually, of course, the distance between the galaxies hits zero, and everything stops because it can’t go any further.
Oh, great. Now what? Did we break the rewind button? No, to the contrary: We just solved the problem.
It’s solved because when everything squishes together into a single point you can’t run the movie back anymore. You’ve hit the beginning. If you note the time stamp on this scene, then you know when it all started.
And that’s pretty much what the scientists did. They used mathematics as a virtual rewind button. Time stamp: 13.8 billion years ago. Name of single point: Big Bang. Mission: accomplished!
But wait, there’s more: As an extra bonus, the Big Bang also demarks the starting point for time itself. The go-to guy for this stuff is the physicist Stephen Hawking, and here’s what he said: “The concept of time has no meaning before the beginning of the universe.”
Actually, according to my calculations, the concept of time has no meaning until the car is paid off and you’ve accrued 20 days of vacation on the books.
But let’s not sweat those details now. After all, having traveled all the way back to the beginning of time today, you probably want to resume happy hour.
So go ahead and order another round. Unless, that is, you’d prefer prunes.