Topic Tuesday #38 2013/04/09 - "Are we alone?"
It's a classic question isn't it? It this planet the only one in the universe that has fostered life in many forms? Worse, perhaps, are Homosapien-sapiens the only "intelligent life" in the universe capable of asking the question?There are a few facts that I am aware of that are amazing at giving a hint to an answer. Some of these facts do little more than to bend the mind and pose more query.
How many stars are in our home galaxy, the Milky Way?
(2×10^11 to 4×10^11) For those that don't like exponents, that's 200,000,000,000 to 400,000,000,000, or 200 billion to 400 billion stars.
How many galaxies in the observable universe?
1.7×10^11 or 170,000,000,000 or 170 billion
How many stars in the observable universe?
3×10^23 or 300,000,000,000,000,000,000,000 or 300 sextillion or 300 thousand billion billion
(according to research by Pieter G. van Dokkum and Charlie Conroy published in December 2010)
This number is comparable more than the number of grains of sand on Earth.
When was the first optical telescope invented?
The year was 1608, or 405 years ago.
When was the first radio telescope invented?
The year was 1937, or 76 years ago.
What is the first known use of written language on Earth?
The Kish tablet dated to ca. 3500 BC is the oldest surviving example of proto-cuneiform signs.
This places evidence of language and recorded history being a time period of roughly 5500 years.
When was the first broadcast of a terrestrial radio signal?
The first experimentation with radio was done in the late 1800's. Marconi made the first radio transmission in 1895. This was 118 years ago.
What does all this amount to? What does this mean?
Every star observed could have planets. Statistically, some of those stars will have planets in the theorized "Goldilocks Zone" where the conditions are just right to promote the conditions to bear life. In short, to think that we are alone, could be attributed to egotism. The odds are not in favor of that conclusion. Then you might think of Martians and crop circles and cattle mutilations and so on. There is a problem with that. It's the problem that we are dealing with every day as we keep looking up. The fundamental speed limit of the universe. The speed of light.
Effectively, looking into space is time travel. No really. Think of it this way, the light or radio signals that we are observing here on our planet, had to travel across space to get here. Radio and light, being energy waves, travel at the same speed. Our closest neighbor, Alpha Centauri, is 4.39 light years away. This is where your head may start to hurt, when you realize that whatever we observe from the 3 stars in the Alpha Centauri system, happened 4.39 years ago. The stars in Alpha Centauri could explode today, and we wouldn't notice until August 29, 2017.
Our star, Sol (aka the Sun), is classified as a G2V main sequence star, roughly middle age at 4.57 billion years. We estimate it has another 4.5 billion years left before it expands to a sub giant, then red giant, then a planetary nebula, and finally, a white dwarf. Our own solar system tells us much of our galactic neighbors. How many planets are possible, what types of planets are likely, the practical ages of stages of star systems. Basically, a wealth of information that builds upon itself to tell us what happened to stars thousands, millions, and billions of light years away from us.
The trick is time and distance. There are stars that we can observe that have already passed through their main sequence (where life is most likely to form). So then we can ponder, what could have happened. As we are aware at this point is that the world will go on without us. The solar system will change, but will go on for billions of years. We are a young species and just dipping our impatient toe in a vast ocean of the unknown.
To reach out to a species on the other side of the galaxy, we will need to learn how to overcome the speed limit. Have other species done this? Impossible to confirm, until they stand here and show us. But it would be unwise to underestimate any possibility. We don't know they would even be interested in talking to us, or eating us.
We are young; our period of intelligence (based on written communication) being less than 6,000 years. The signals that are most likely to be noticed, to say that we are here, have been traveling into space for no more than 118 years. We need to take the long view and have patience.
Our culture has been shaped to be very self centered. For examples;
"The world was made for man."
"The Sun revolves around the Earth, and the Earth does not move."
"The stars revolve around us, if not Earth, certainly the Sun."
"Certainly we are at the center of the universe."
"Everything was made for us, for our time here. It all lead up to this moment."
Seeing stars explode and scatter their enriched guts across space to feed the creation of another world, I find it remarkably egotistical to think that; our small planet, in an average solar system, around an average star, in an equally unremarkable arm of one of 170 billion galaxies... could somehow be more special than any other.
We are very lucky to have made it this far. It is doubtful we are alone, but it is even more doubtful that the other intelligent life has survived to make contact with us, or that they would have even noticed us yet. Should we stop looking? Never. There is still a chance, even if it is small. While we look, we learn. One day, when we take to the stars as a space faring race, escaping from an expanding star (or whatever else we may have done), we will need to have a destination.
We need to survive long enough to do this, so smile and hug your fellow man. Know we are children. We will make mistakes. We just need to keep some perspective. We're only human.