Everyday Is Better Than The Next

I would say that I spend a lot of time studying how the universe works. I have read many books about the planets, astronomy, cosmology, physics, special relativity, general relativity, quantum mechanics, entropy and the second law of thermodynamics, the big bang, etc, etc. The point is that I feel that I have a general understanding of the basics of how the universe operates. In dealing with things about our universe it is sometimes hard to get your mind around the enormous numbers that are involved when one thinks “universally”. Our minds are not able to comprehend numbers like a million billion or two hundred and fifty thousand light-years. We have no such frame of reference for that kind of number. We are much more comfortable with smaller numbers because that is what we deal with on a daily basis. We can easily asses how far 150 miles is, but we have trouble with 150 light-years. We can look at a pile of rocks and easily estimate their quantity, but we would be hard pressed to estimate the number of stars in the night sky.

Every now and then I catch myself taking these large numbers for granted. Today is one of those days. I came across an image today that really made me think about how large these numbers really are and how tiny and insignificant they can make me feel.

The above image (click for a larger view) is an artists rendition of our galaxy, the Milky Way. While looking at that picture you may think that the white chalky looking area in between the arms is dust or gas clouds. While some of it is, for the most part these “clouds” are actually all stars, but they are so tiny in this picture that they give the appearance of being a cloud. This is the same way that your TV works. Each individual pixel makes up the entire picture. If your TV screen was completely white you wouldn’t be able to tell the difference between the pixels and it would appear is if the screen was a solid white. But, before we get ahead of ourselves let’s first define what a galaxy is. Most people are familiar with the idea that we live on the planet earth which, along with some other planets that make up the solar system, are in orbit around the sun. What some people may not be familiar with is that our solar system is part of a large (very very large) group of stars that make the Milky Way galaxy.

It is estimated that there are somewhere between 100 billion and 400 billion stars in our galaxy. The truth is that we don’t know the true number for a couple of reasons. First of all the fact that we are situated in the Milky Way prevents us from seeing the other side. Secondly, the most common type of stars are a class known as red dwarfs. Red dwarfs are a small type of star that do put out a lot of light, and therefore we can’t see all of them. And finally, the number of stars is just overwhelming. Let’s say there were 250 billion stars in our galaxy. If it took one second to count each one (which it does not), it would take us 7,900 years to count them all. For humors sake, let’s look at comparison. If every star in the Milky Way was a grain of salt they would fill an Olympic sized swimming pool. Just think, spinning around just one of those grains of salt there is a planet called Earth and you are standing on it.

So now that we have a better understanding of our galaxy let’s take a look at the distances involved. Since light travels at a constant speed, light is what we use to measure great distances in our universe. Light travels at about 186,282 miles per second, or to compare it to a measurement that we are familiar with such as the speed of a car light moves at 983,571,056 miles per hour. That number alone is almost incomprehensible. What makes it even more incomprehensible is the fact that distances to stars, across galaxies, and to other galaxies is measured in light years. The closest star to us is the faint, red dwarf star called Proxima Centauri. This star is only 4.2 light-years away. The light we see from this star has traveled for 1,500 days. That means that when we look at Prixima Centauri, we are actually looking back in time. The farther away an object is, the farther back in time we are actually looking. Let’s look at another example of “seeing into the past”. The closest spiral galaxy to us is Andromeda, a galaxy much like our own Milky Way. It is 2.5 million light years away from us. That means that when we look at Andromeda, we are actually seeing what it looked like 2.5 million years ago. To put that in perspective, 2.5 million years ago was right around the the dawn of man.

All that I have talked about up to this point was our own galaxy. Although it may be hard to get a grip on what these incredibly large numbers actually mean, this next set is even more mind boggling. Our galaxy is one of about 125 billion other galaxies in the known universe. Again, we don’t know the exact number and we may never know the exact number. If you do the math with rough estimates of the number of galaxies in the universe and the number of stars in a galaxy what you come up with is that there are more stars in the universe than there are grains of sand on all the beaches of the earth. Earlier I said that if all the stars in our galaxy were the size of a grain of salt they would fill an Olympic sized swimming pool. Think about 125 billion Olympic sized swimming pools all filled with salt. And remember, in one of those 125 billion pools, spinning around one of those grains of salt there is a planet called Earth and you are standing on it. If that doesn’t make you feel completely insignificant, then I don’t know what would.

What does this insignificance mean though? That is the question that I ask myself every day. When you realize that anything that you do won’t really have any effect on the outcome of anything in the grand scheme of things, what is the point of getting up in the morning? Why bother? It’s not like it’s going to change anything. Our galaxy will still continue hurtling though the universe. The sun will continue to rotate around our galaxy. Earth will continue spinning around the sun.

Further Reading:
Scale of the Universe
The Fabric of the Cosmos: Space, Time, and the Texture of Reality