Archive for Wednesday, December 27, 2006

The science of really big numbers

December 27, 2006

How many miles wide is our Milky Way Galaxy? Traveling in our fastest spaceship at 25,000 mph, how long would it take to reach the Andromeda Galaxy, one of the closest galaxies to our own? How many atoms are there in a drop of water? How many cells are in the human body?

These are all valid and interesting questions, but sometimes in science the answers you get sound so far out they are, for all practical purposes, meaningless. It's not too hard to imagine 100 of something, or even 10,000. Those are real numbers that we can conceive and picture in our brains. Now let's kick it up a notch -- such as the recent news that the United States just hatched its three hundred millionth citizen; a pretty big number to be sure, but still within the realm of our comprehension.

What if I told you the Milky Way Galaxy is 568,036,800,000,000,000 miles wide; it would "only" take 469,255,680,000,000 years to reach the Andromeda Galaxy in our speedy rocket; a drop of water contains 4,000,000,000,000,000,000,000 atoms; and the human body is made up of about 100,000,000,000,000 cells?

Now I don't know about you, but those numbers mean nothing to me. I look at them and all I can tell you is those are big numbers. Now there's a profound statement, to be sure. The only way numbers of that magnitude could have any meaning or relevance is to put them in a context that we can begin to be able to wrap our brains around.

For example, there are approximately 100 billion stars in our galaxy (which is an average sized galaxy), and there are an estimated 200 billion galaxies in the observable universe.

By multiplying these two figures, we can calculate there are about 20,000,000,000,000,000,000,000 stars in the universe which, interestingly, is about five times as many atoms in a drop of water.

To put this in perspective, there are about as many stars in the universe as there are grains of sand on every beach, sand dune, ocean floor and river bed on Earth. It's also about equal to the number of cups of water in every ocean, river, lake, ice cap and glacier on Earth. Bottom line: It's a lot! But at least we now have a reference point.

As I think about the significance of this, two points come to mind.

The first is that it is understandable why science seems so difficult and unapproachable and thus turns people off. Complicated concepts and far out facts intimidate us and tend to frighten us from further study. We question the relevance to our everyday lives; after all, who really cares how wide our galaxy is?

But to me, this is precisely what makes science so fascinating and awe-inspiring. To think we live in such a spectacularly vast and complex universe evokes a sense of wonder and astonishment. The very act of understanding and discovery allows us to wade, if only ankle deep, into the bottomless pool of nature and all she has to show us.

Johannes Kepler (1571-1630), German mathematician and astronomer, said: "The diversity of the phenomena of Nature is so great, and the treasure hidden in the heavens so rich, precisely in order that the human mind shall never be lacking in fresh nourishment."

So come on in. The water's fine.

- Tonganoxie dentist Grant Ritchey can be reached via e-mail at

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