Over the last week or so I have been going back and forth with a friend about the timeline in the Terminator movies. With the new one coming out, the old ones have been on cable. I either forgot or I was unaware that they had made a fourth movie, based around the John Connor character, so I watched it the other day. That film tries to address the timeline issue, which is what spawned the discussion.

The trouble with time travel, of course, is the paradox. In this case, sending Kyle Reese back in time could alter the timeline in such a way that the future no longer includes the possibility of sending that same guy back in time. That’s the paradox. It is the old bit about going back in time to kill your parents. It’s a logical impossibility.

Therefore, the only way the movies can make any sense is if the future guy is destined to be a part of the natural timeline. Your attempt to go back and kill your parents always fails, but in the attempt, events are shaped in such a way that you one day decide to go back in time to kill your parents. Lather. Rinse. Repeat.

In the movie four they try to tidy up this bit of the plot, so they make it clear that John Connor knows how this works. He knows he sends his father back in time to save his mother. The trouble with that is he could roll the dice and decide to just shoot the man destined to be his father, thus scrambling the whole thing, but then that would mean someone else was his father.

The point here is that time travel as a plot devise is fine as long as you don’t think about it too much. The only way to make it work logically is to either accept determinism or the multiverse. The former naturally appeals to humans, while the latter is incomprehensible to most people, so Hollywood preaches a weird form of fatalism in these movies.

There’s a similar problem with space aliens. Logic say that intelligent life evolving on another planet is most likely going to look a lot like us.

They are often portrayed on screen as little green men with elongated limbs and saucer-like eyes.

From E.T to the X-Files, aliens from outer space have captured our imagination for decades.

Yet a new book from a leading evolutionary biologist argues that if they exist and we ever encountered them, they would look very similar to us.

Professor Simon Conway Morris said extra-terrestrials that resemble human beings should have evolved on at least some of the many Earth-like planets that have been discovered by astronomers.

This is most certainly true, to a point. A planet the size of earth orbiting a sun similar to ours would probably be very similar to earth. In order to support carbon based life of any complexity it will need to look very much like earth. An intelligent species evolving on an earth like planet will therefore come out pretty close to humans. Maybe all the smart people are black instead of Chinese, but otherwise things would be pretty close.

“An area of biology which is becoming popular, perhaps too popular, that the possibility evolution is becoming much more predictable than people thought,” he told The Independent. “The book is really trying to persuade the world that evolutionary convergence is completely ubiquitous. Wherever you look you see it.

“The theme is to try and drive the reader, gently of course, into the possibility that the things which we regard as most important, ie cognitive sophistication, large brains, intelligence, tool making, are also convergent. Therefore, in principle, other Earth-like planets should very much end up with the same sort of arrangement.”

Professor Conway Morris, a Fellow at St John’s College, said it follows that plant and animal life on other planets able to support life would also look similar to Earth’s.

He said: “Certainly it’s not the case that every Earth-like planet will have life let alone humanoids. But if you want a sophisticated plant it will look awfully like a flower. If you want a fly there’s only a few ways you can do that. If you want to swim, like a shark, there’s only a few ways you can do that. If you want to invent warm-bloodedness, like birds and mammals, there’s only a few ways to do that.

The missing bit here is we don’t know what we will look like 10,000 years from now. We know, for example, that humans as a whole are about ten points dumber now than in the Victorian era. The main reason for that is stupidity is not as lethal as it was then. Similarly, we are physically weaker as a whole, due to the fact we do far less physical labor.

An intelligent life form on another planet that is able to traverse the stars to reach earth will be vastly more advanced than us and therefore further down the timeline of evolution. If the artificial intelligence people are right, they will have long ago figured out how to upload their consciousness into the machine and will no longer be organic, as we currently understand it.

Of course, a species with the ability to traverse the stars will surely have the ability to cloak their presence from us anyway. Therefore, the only way we will ever encounter space aliens is when we evolve to the point where we can traverse the stars and meet them halfway. Alternatively, we will see the humanoids of another planet when we visit, but they will look like retarded apes to us as we will have evolved well beyond our current meat stick form.

In other words, there are no little green men and even if there were, they would not reveal themselves to us anyway.