It is my belief that people who do not believe in evolution are simply suffering from a lack of imagination. That is, they have trouble imagining just how big the universe is and just how long evolution has been trying to "get it right." Hidden behind every remarkable adaptation are thousands of creatures who did *not* get it right (due to partial or unsuccessful adaptations), and died as a result.
One of my favorite quotes is:
The universe is huge and old, and rare things happen all the time
-- Lawrence Krauss, physicist (see his talk on youtube).
As finite humans with an extremely limited worldview, it's difficult for us to comprehend just how big and how old the universe actually is. With the help of Wolfram Alpha, a remarkable information calculator, we can make those numbers more approachable. In order to wrap our heads around these huge concepts, let's compare these numbers to something we know.
How old is the universe?
You may have heard this analogy before, but it's really good so I'm just repeating it here.
What if we took the entire history of the universe since the big bang and compressed it down to a single 24-hour day? The formation of the stars, the formation of the planets, the emergence of the dinosaurs, the first appearance of humans, all the way up to today.
In that 24-hour day, the earth was formed at approximately 4:03pm (7 hours, 57 minutes ago)
The first humans appeared at 11:58.74pm that is, 1.26 seconds ago
And all of recorded history has happened in less than the time it takes you to blink (much, much less).
So, as important as we think we are, we humans simply have not been around very long. What has been happening all that time? A lot. And it has had nothing to do with any of us.
How big is the universe?
I'm going to make some approximations for the sake of simplicity. Just a few generations ago, the average human traveled no more than 25 miles from her birthplace during her entire life. Nowadays, it's not uncommon for a person to fly all over the world, even several times a week for some people!
While we as a species have managed to get off of our planet a few times in our very recent history, we have never visited another star besides our own.
How many stars are there in the known universe? Wolfram Alpha says: 3x1023 (NOTE: This number keeps going up every time I check.)
Let's shrink things down a bit. Let's imagine, for a moment, that our entire solar system - Mercery, Venus, Earth, all of them, all the way out to Pluto (because I'm old-school) - is the size of a single AA battery. And not the long-way either, just the round part, like you're looking down at the top. That little nipple on the top of the battery is our sun and the rings around it are the planets.
If we were to line up all the stars in the universe (as represented by AA batteries) side by side, how much space would they take up? We're standing the batteries up on their ends, so each circle touches four others (assuming a basic grid placement in rows & columns). So we multple the number of stars above by the diameter of a AA battery, squared: the batteries would cover an area 6.049 x 1013 km2
That's still a really big number. Let's shrink it down again. Most of us know how big a US football field is from having watched or played a game. How many batteries can we fit in a football field? 2.7x107 - that's 27,000,000 - twenty seven million batteries stood on their ends.
So how many football fields are we talking about? Dividing the number above by the area of a football field we get: 1.1 x 1016 - that's still too big to comprehend.
What if we covered the entire Earth with batteries, including all the oceans? With the number of stars in the universe (that we know about right now), it would cover the entire surface of the Earth 118,596 times over.
If we shrank the Earth itself to the size of a battery, and lined them up (still standing on end) side-by-side, they would stretch out for just over a mile, that's 18 football fields lined up end-to-end.
Imagine that we -- all of us, everyone you've ever met, everyone you've ever heard of, everyone who has ever lived - all exist on the top of one AA battery. There are batteries lined up in every direction as far as you can see. You can get on an airplane and fly to any part of the world and the ground is completely covered with batteries. All the oceans are covered with batteries. All you can see from your airplane is shiny metal tops everywhere. Now take the Earth and shrink it again to the size of one of those battery tops. Line up batteries for a mile. That's 18 football fields placed end-to-end. Imagine walking a football field. Next to your little toe is a planet the size of Earth, covered in batteries, each battery representing a star in the known universe. Out of all those stars, we've been to exactly one of them.
The universe is huge.
For the grognards, here are some notes about my models:
- All solar systems are not the same size, so some batteries would be bigger than others.
- Stars are not equidistant from each other, in fact there is a lot of room in between some of them. The batteries would not be right next to each other, but separated by some distance.
- This is not the most efficient packing of circular objects, but it's easier to understand.
- We have not "been to" the sun, but rather to a planet orbiting the sun.
Correcting for these assumptions would only make the universe even bigger.