I’ve always been quite fascinated by astronomy and/or cosmology. The two terms are often used interchangeably, but cosmology can sometimes imply a bit more speculation and philosophy than astronomy.
When dealing with this field, one requires some rather lengthy measurements, to say the least. You may recall from a high school physics class that light travels at roughly 190,000 miles per second. A light-year – that is, the distance light travels in a year – is roughly 6 trillion miles. That figure is the foundation for many scientific equations and measurements in astronomy.
Of course, stars are simply suns. They may be larger or smaller, brighter or dimmer than our sun, but they’re suns nonetheless. A galaxy is defined as a cluster of stars; that is, stars that tend to congregate.
A galaxy contains at least 40 billion stars and can have as many as 100 billion. And, in case you have trouble getting your mind around that, the universe contains more than 100 billion galaxies, give or take a few billion. (Hold up a penny against the night sky and you block three galaxies from your view.) That’s like 100 sillion, octillion, zillion stars, most of which may have planets zinging around them.
It’s quite reasonable to assume that somewhere in that cosmic soup there are other forms of life. Even intelligent life.
And yet, despite those billions upon trillions upon zillions of suns and planets, the universe is 99 percent space. In fact, for illustrative purposes, if there were only three flies in the Earth’s atmosphere, our air would still be more crowded with flies than space is with stars!
All this space really isn’t empty. There’s a lot of stuff shooting around in it. Dust. Subatomic particles. Comets. Whatever.
The universe is expanding quite rapidly, even in cosmic terms. All the galaxies are flying away from each other. This is why scientists feel some awesome explosion – the Big Bang – must have occurred in the distant past and the universe has been flying apart ever since.
When did this explosion happen? Well, it’s a bit ridiculous to even raise the question, but some Harvard mathematicians have playfully attempted an answer. By making a preposterous estimate of the amount of matter in the cosmos (talk about an estimate that’s so much bovine excrement!) and combining this with the speed of expansion, effects of gravity and a few other odds and ends, they’ve concluded, with impish little smiles, that the Big Bang occurred around 15 billion years ago.
The Hubble telescope is currently looking at the light from stars that are 15 billion light years away. That’s right, friends, stars that are 84,000,000,000,000,000,000,000 miles from Earth. Of course, the stars in question may no longer exist because the light from them – the light we’re seeing – took 15 billion years to get here. So, we’re actually looking back in time; seeing stars as they looked 15 billion years ago, shortly after the Big Bang. This is what astronomers mean when they speak of the “edge” or the “end” of the universe.
As you may surmise, such figures and distances have certain philosophical consequences. More on these thoughts next week, if you can imagine or tolerate such a thing.