Saturday, August 23, 2008

How big is Big?

So, Okada and I were having a discussion recently on the likelihood of evolution, and it started making me think of the size of the universe, how long it's been in existence, and the inability of humans to really comprehend such things. I consulted NOVA's website (one of the COOLEST places online) and got a few basic numbers, which I'll do my best to break down for everybody and give you some rough idea of just how significant we really are in the universe.

A warning: there are big numbers below the fold...

Okay, let's start off with the concept known as a "light-year." It's a term lots of us are familiar with thanks to Star Trek and the like, but just what is it? Well, light travels at roughly 300,000 kilometers per second (186,411.36 miles/sec). So, with a quick bit of number crunching later, we know that light travels at 9,467,280,000,000 kilometers per year (300,000 x 60 x 60 x 24 x 365.25), which gives us the distance of a light-year: over 9 trillion kilometers.

So, now that we have that number down, let's go with figuring out how big the universe really is. The closest galaxy to our own Milky Way of any real size is Andromeda, which is 2 million light-years away. That translates as 18,934,560,000,000,000,000 kilometers away. The farthest point in the universe that we can see is about 12 billion light-years away, which is a whopping 113,607,360,000,000,000,000,000 kilometers away. Now, keep in mind that's a radius, not an area or anything like that. That is the distance from us, the center of our visual sphere of the universe. There is another 12 billion light years in every other direction. Our visual sphere's volume is a number that is just astronomical...6.141974554241230393692905613093x10^69 cubic kilometers.

I've started throwing around the term "visual sphere," and I think I should elaborate on that a bit. Since we rely on light to see these distances, we can only see something that's as far away as light has had time to travel. So, if it's the 12-14 billion light years or so away from us and sheds light, we can see it here now. That forms our visual sphere of the universe. That means the universe is possibly much, much larger than what we can see.

So, let's say you want to make the ultimate road trip and drive over to Andromeda for the weekend. We've all been in a car going at 60 miles per hour, which translates as 96 kilometers per hour. To drive from Earth's surface to the edge of Andromeda, it would take our interstellar Prius approximately 23,478,260,869,565 years. You can do the gas math for that one if you really want to.

Now, you can look at these numbers and think about how big the universe is. Really think about it for a second...something you may notice is that our minds are incapable of wrapping around ideas like 2 billion light-years. Hell, we can barely comprehend what 10,000 is. Don't believe me? Try this game...imagine a penny. One tiny little piece of copper-plated zinc with the face of Lincoln stamped on it. Not hard to do, right?

Try ten pennies. Ten Lincolns in a row. Not even breaking a sweat, are you? Now do one hundred; ten rows of ten. You've probably seen this before in your lifetime, so no big deal. What about a thousand pennies? That square of 100 pennies stacked ten high. Okay, sure. Ten-thousand? One-hundred-thousand? A million? How high can you go before you can no longer picture the size of that number of pennies? It doesn't take too many zeros before it becomes impossible. (Fun fact: according to various sources, there are somewhere between 140- and 200-billion pennies in circulation today) Do this exercise with seconds (Okada's favorite method) and you'll get the same idea about time.

So, with your newfound knowledge of just how big the universe is, and just how old it has to be in order for us to have seen the horizon of our visual sphere, how is it hard to believe that evolution can and did occur? And is it that much more of a stretch to say that something as advanced as humanity could spring up from the innumerable cellular developments that occurred over the 14 billion-or-so year span? Is it hard to believe that it could *gasp* happen again, somewhere else?

1 comment:

Ragoth said...

One quick note, the age of our solar system is about 4.5 billion years old, as we are orbiting a second or third generation star (which, also wik, is why we have heavier elements like say, uranium and iron. Fun!) Now, life appeared almost immediately after the cooling of the Earth. It took around 3 billion years for life to advance to multicellular forms, but once that happened (probably due to slow changes in atmospheric concentrations and other factors), life exploded. Which, really, this should tell you something about just how robust and adaptive life is. In other words, to look at the evolutionary history of the world (and the greater astrophysical history of the universe), is to witness "endless forms most beautiful."

So, summing up, evolution on earth has happened within the last 4.5 billion years, but this shorter time-span really bespeaks the remarkable ubiquity of organic compounds in the universe, the wide range of conditions under which life can occur, and it's hardy robustness.