Exoplanets Suitable for Life

Recently astronomers have discovered planets in orbit around most stars close enough to determine whether they have planets. But of all those billions of planetary systems, which have planets capable of supporting life? At present we do not have the technology to look closely at those systems. Of our own solar system, as far as we can tell, earth is the only one capable of supporting life. There are two other planets that might support life. Mars may have supported life in the past, but so far no concrete evidence of this has discovered. Europa, a moon of Jupiter, has a liquid ocean. Perhaps life developed there (if the ocean is water).

So what makes earth unique in the solar system. First, it is not too hot nor too cold to sustain life. Most of the planets and moons further from the sun than Mars are too cold. Mercury and Venus are too hot. Although Venus is not so close to the sun that a temperature within a range to support life is ruled out for that reason. Venus is sometimes regarded as earth's sister planet. Venus is only slightly smaller than Earth (95% of Earth's diameter, 80% of Earth's mass). Because of these similarities, it was thought that below its dense clouds Venus might be very Earth like and might even have life. Unfortunately, we now know that Venus may be the least hospitable place for life in the solar system.

The pressure of Venus' atmosphere at the surface is about the same as the pressure at a depth of one km in Earth's oceans. It is composed mostly of carbon dioxide. There are several layers of clouds many kilometers thick composed of sulfuric acid. These clouds completely obscure our view of the surface. This dense atmosphere produces a runaway greenhouse effect that raises Venus' surface temperature hot enough to melt lead. Venus' surface is actually hotter than Mercury's despite being nearly twice as far from the Sun.

Another factor to support life as we know it is the presence of water. Apparently Mars once had liquid water on its surface, but it no longer does. Another problem with Mars is its thin atmosphere. One possible reason that it no longer has water and air is its small mass. Any smaller planet would likely be completely airless like our own moon.

Hence, it can be seen that although three planets are in a zone capable of supporting life as far as distance from our star (the sun), only one can support life. The other two are too dry. One has an atmosphere that is too thick, the other an atmosphere that is too thin. Thus, it can be seen that planets capable of supporting life are relatively rare. The question is how rare. If ten percent of planets in the galaxy are capable of supporting life, there may be nine billion planet capable of supporting life. If this number is one percent there would nine hundred million; one tenth of one percent , ninety million. That's still a lot of planets capable of supporting life.

What's Beyond the Universe

Have you ever thought about infinity? Or read what modern cosmologists have to say about the universe? Back a few centuries, people who thought about such things figured that the universe consisted of the earth which was surround by crystal spheres. Astronomers (actually astrologers) of those days never wrote about what was outside the outermost crystal sphere. Then came along Copernicus, Galileo and Newton and the universe expanded somewhat to the size of the solar system and the fixed stars out there somewhere; nobody knew how far. When astronomers gazed through more powerful telescopes and other sophisticated gear, suddenly the universe expanded to billions of light years in size.

But how far did it go? Did it stretch on forever? In the early part of the twentieth century, Albert Einstein proposed his Theory of Relativity. This and other discoveries changed everything. Cosmologists began to think of the universe as a great expanding ball (or some other shape) that had a definite limit.

Okay, that is the current view of our universe. But if our universe is a great ball (or some other shape) curved in the fourth dimension, what lies outside of it? Recent articles I have read about what modern cosmologists and physicist think about the universe speak of "multiverses." I wonder what they are like.

Here are some thoughts on the matter. Not all of them are mine. According to one viewpoint,. the universe is defined to be everything, including space and time itself. Since the universe includes all space, there can be nothing "outside" the universe.

However, the Big Bang theory changed the view of cosmologists and others who study such things completely. According to the Big Bang theory, the Big Bang was not an explosion in a preexisting three-dimensional space, with matter and light expanding out into empty space from some central point; instead, matter and energy are understood to fill all of space (i.e. "the universe"), and what's expanding is space ("the universe") itself. But, wait a minute, if it's expanding, what is it expanding into?

The Big Bang theory is based on Einstein's theory of general relativity, which explains that gravity of matter/energy causes space-time to curve. The amount of curve depends on the average density of matter/energy throughout the universe, a consequence of this is that the universe as a whole can be curved, with either positive curvature, zero curvature, or negative curvature.

To visualize a closed universe with positive curvature, drop the dimensions by one. Instead of curved three-dimensional space, picture a two-dimensional universe in which two-dimensional space is curved into a sphere, and "expanding space" means that the sphere is blowing up like a balloon while the bits of two dimensional matter on the surface do not change in size. You can see that if you pasted a bunch of bits of paper on a balloon and then blew it up, each bit would see the other bits receding from it. This is what astronomers observe, when they view distant galaxies.

If you made a movie of the balloon blowing up and play the movie backwards, after a while the size of the sphere approaches zero, all the bits of matter throughout the balloon universe get more and more squished together and approach infinite density as the size approaches zero. This is what the big bang is supposed to be. Of course, this analogy forces you to picture the two dimensional surface of the sphere expanding into a third dimension, and our curved three dimensional space is expanding into four dimensional space. The question becomes what else is in the fourth dimensional space? Other balloons (universes)?

Also, if space is curved in the fourth dimension, what happens if you travel in a straight line as far as you could go? Would you return to your starting point? And if the fourth dimension is time, would you return to the point in time when you started your journey?

On the other hand, J. Bruno wrote: "The center of the universe is everywhere, as well as its border but does not exist anywhere." Thus, the universe has a center that exists everywhere and borders that exist everywhere. Think about this. Does this statement violate any physical or philosophical rules or not? If the answer is "not," the universe is and will stay infinite and isotropic.

Not everyone agrees. According to Stephen Hawkins, a black hole transports information to another universe. Another theory hypothesizes that there are many (perhaps an infinite number of) universes outside our own. In fact, one theory is that there is a larger universe of which our universe is only a part, like an atom of something much larger.

There is also the theory of parallel universes in which a new universe is created whenever two or more possible futures occur. That each possibility creates a new universe which is almost identical to the ones parallel to it except in one the change occurred one way, and in the other, it occurred the other way.

Of course, all this brings up the question of what is the universe composed. When we say that space is curved, what is this curved "space" composed of? Nothing? How can nothing be curved? It seems that there are more questions than answers. For more confusing answers and questions, go to any web site on modern cosmology.

Computers That Learn

One of the great themes of science fiction is the computer that becomes as smart or smarter than a human being although not many novels and movies have been made in which this is the central theme. Off hand I can only think of a couple of movies, Colossus the Forbin Project and HAL in 2001, A Space Odyssey. In most science fiction the thinking machines are robots. At present computers can do many marvelous things, but none can compare with the human brain that makes sense of countless diverse, quickly changing stimuli without effort. Doing what we do with ease is often an impossible task for computers.

Nonetheless, researchers in artificial intelligence are hard at work trying to achieve the goal of computers that think as well or better than a human being. For example, Researchers at the Leipzig Max Planck Institute for Human Cognitive and Brain Sciences and the Wellcome Trust Centre for Neuroimaging in London have developed a mathematical model which could significantly improve the automatic recognition and processing of spoken language. In the future, such algorithms that imitate brain mechanisms could help machines perceive the world around them. Perception of its environment would go a long way toward achieving true artificial intelligence.

If you've ever had to deal with a voice activated automated telephone system, you probably realize how difficult it is for a computer to understand even simple words. If you speak a little too quickly or slowly, if your pronunciation is not clear, or if there is background noise, the system fails to understand you.

According to Stefen Kiebel of the Leipzig Max Plank Institute, the brain classifies the various signals from the smallest, fast-changing components such as single sound units like a vowel or consonant up to big, slow-changing elements such as the topic. The significance of the information at various duration levels is probably much greater than previously thought for the processing of perceived information. The brain searches for time dependent structures in the environment to determine what happens next. In this way, the brain can, for example, predict the next sound based on the slower-changing information.

To test this hypothesis, the researchers constructed a mathematical model to imitate, in a highly simplified manner, the brain processes that occur during the comprehension of speech. The processes were described by algorithms that process speech at different duration levels. The model succeeded well. In contrast to other artificial speech recognition devices, it could process speeded up speech sequences. In addition it could predict the next speech sound. If a prediction turned out to be wrong, the model detected the error. This indicates that the model represented processes in a way that was similar to the way the brain functions.

This new approach may be the beginning of a truly intelligent computer.

Armageddon in Science Fiction

One of the most reoccurring themes in science fiction is the end of the world, or at least the end of civilization. It is not surprising since there are many ways that this could actually come about. Also, prophets have been predicting catastrophic disasters from the time men learned to speak to each other. Two popular ones lately are global warming and an asteroid strike. So we have a choice of drowning when the ice caps melt or being smashed to atoms by a big rock.

For a while, when a few people caught bird flu in Asia, pandemics were all the rage. In the latter half of the twentieth century, everyone was betting on an all-out atomic war, but that fizzled when the cold war ended. Recently, I read article about a scientist who said we could all die from a burst of gamma ray radiation from a nearby supernova explosion. As the clock struck midnight ushering in the year 2000, all the computers were supposed go mad because they only had the last two digits of the year and could not distinguish between the twentieth and twenty-first century (which to some people did not start until 2001 anyway.)

Anyway, science fiction authors love to write about Armageddon of one sort or other. Here are some of my personal favorites. There are two by John Brunner. The first is Stand on Zanzibar where civilization is brought to an end because of overpopulation. Overpopulation as threat seems to be no longer in vogue. I guess because there are so many ways of dealing with overpopulation. For example, nuke the excess or give everybody a gun and give them leave to hunt and kill everybody they hate.

The second book by Brunner is The Sheep Look Up which is about pollution. We are pretty certain that is the most likely end that we face.

There are many atomic war novels. These were especially popular during the cold war years. The funniest was the movie Doctor Strangelove, where a deranged general starts world war three because of his erectile dysfunction. I also like the novel On the Beach by Nevil Schute, which was also made into a good movie. In this novel, the last people on earth after an atomic war are living in Australia waiting to die from the radioactivity produced by all those hydrogen bombs going off. Probably my all time favorite about a post apocalyptic world is Canticle for Leibowitz by Walter Miller where a monk finds an artifact from our civilization after civilization has gone back to the dark ages.

One of the more interesting ways that the human race comes to an end is a little known book called The Black Corridor by Michael Moorcock. In this short novel, bigotry runs wild so that everyone kills everyone else that is different from himself or herself. It's a real chiller. I got goose bumps reading it.

Invasions by aliens is another possibility that could end the human race. My favorite is Footfall by Larry Niven and Jerry Pournelle, where the invaders look like elephants.

An old movie that's fun is When Worlds Collide where a group of scientists and a chosen few race to build a spaceship to escape from a collusion between earth and another planet. The one thing I never quite understood was where the planet they were headed for was located

I liked the TV miniseries The Stand by Stephen King as the survivors of a pandemic meet up at the cabin of an old woman and go fight the devil in Las Vegas.

Of course there are many more great science fiction novels and stories about the Apocalypse, but those were some of my personal favorites, because they each have a slightly odd slant to the end of the world.

I have written one novel about Armageddon myself. It is called Morgaine and Armageddon and has a lot of stuff in it based loosely on The Book of Revelations of the Christian Bible. If you are interested, it is in E-book format and can be obtained from most online E-book sellers such as Amazon and Barnes and Noble.