Is there life elsewhere?

The question is: Is there Life elsewhere in our Galaxy? I’m going back to an old blog 409, where at the bottom Professor Brian Cox thwarted suggestions alien life was a possibility and said he believed humans were the only form of civilisation in our galaxy, despite the astronomical number of other planets in it. 

I have previously quoted Paul Davies as saying: "The chance of life arising is as slim as throwing six pick-up sticks (or nails) on the table, and they end up intersecting in the one spot. Next to zero!"

But recently I have written about the theory of the Five Filters, blogs 941 and 942 ... it talks about the  rising of life in the first instance as single cell beings (the First Filter). This is the crux of the matter: How did life evolve in the very first instance, where single cell, living beings separated from inanimate matter.

Scientists have no idea where and when this has happened. But is is now largely accepted that once single cell beings exist, the step to overcome the Second Filter and indeed the Third are not too much of a mystery. And those single cell beings?

Well, it is mooted they can travel in space. They potentially can survive for millions of years on an icy asteroid ... get carried around the galaxy and seed life on any planet that will support it. So the life would not have to be 'created' over and again in various locales at all. A neat theory.

The trick is to overcome the various Filters, up to the Fourth. That's where we are as humans on Earth. Where to from here? We may have to overcome the Fifth Filter ... or be consumed by it. As have any potential previous alien civilisations, since we can't seem to be able to find aliens ... the Fermi Paradox. I have written an essay on that subject matter  THE FUTURE II

But back to single cell beings, the rising of life in the very first instance: It probably only happened once, in a galaxy far far away; we are the children of those primordial beings and our brothers and sisters are roaming the universe frozen in intergalactic ice, carried around by asteroids. Cool.


A while ago Paul Davies wrote another article  Are We Alone in the Universe?


THE recent announcement by a team of astronomers that there could be as many as 40 billion habitable planets in our galaxy has further fuelled the speculation, popular even among many distinguished scientists, that the universe is teeming with life. 

The astronomer Geoffrey W. Marcy of the University of California, Berkeley, an experienced planet hunter and co-author of the study that generated the finding, said that it “represents one great leap toward the possibility of life, including intelligent life, in the universe.”


But “possibility” is not the same as likelihood. If a planet is to be inhabited rather than merely habitable, two basic requirements must be met: the planet must first be suitable and then life must emerge on it at some stage.      


What can be said about the chances of life starting up on a habitable planet? Darwin gave us a powerful explanation of how life on Earth evolved over billions of years, but he would not be drawn out on the question of how life got going in the first place. “One might as well speculate about the origin of matter,” he quipped. 

In spite of intensive research, scientists are still very much in the dark about the mechanism that transformed a nonliving chemical soup into a living cell. But without knowing the process that produced life, the odds of its happening can’t be estimated.


When I was a student in the 1960s, the prevailing view among scientists was that life on Earth was a freak phenomenon, the result of a sequence of chemical accidents so rare that they would be unlikely to have happened twice in the observable universe. “Man at last knows he is alone in the unfeeling immensity of the universe, out of which he has emerged only by chance,” wrote the biologist Jacques Monod. Today the pendulum has swung dramatically, and many distinguished scientists claim that life will almost inevitably arise in Earthlike conditions. Yet this decisive shift in view is based on little more than a hunch, rather than an improved understanding of life’s origin.


The underlying problem is complexity. Even the simplest bacterium is, at the molecular level, staggeringly complex. Although we have no idea of the minimal complexity of a living organism, it is likely to be very high. It could be that some sort of complexifying principle operates in nature, serving to drive a chaotic mix of chemicals on a fast track to a primitive microbe. If so, no hint of such a principle has been found in laboratory experiments to re-create the basic building blocks of life.


On the other hand, if life arose simply by the accumulation of many specific chemical accidents in one place, it is easy to imagine that only one in, say, a trillion trillion habitable planets would ever host such a dream run. Set against a number that big - and once you decide a series of unlikely accidents is behind the creation of life, you get enormous odds very easily - it is irrelevant whether the Milky Way contains 40 billion habitable planets or just a handful. Forty billion makes hardly a dent in a trillion trillion. 


So we are stuck. Life may indeed pop up readily in Earthlike conditions, or it may be a fluke, unique in the observable universe. Because we are a product of this cosmic accident, we cannot conclude that Earth is typical. No statistical evidence can be drawn from a sample of one.


The easiest way to settle the matter is to find a second sample of life, one that arose from scratch independent of known life. The inventory of extrasolar planets being discovered is an extremely useful first step. In the future, our telescopes should be able to analyze the atmospheres of some of these planets for telltale signs of biological activity.


But evidence favoring life’s high probability could exist closer to home. No planet is more Earthlike than Earth itself. If life does pop up readily in Earthlike conditions, then it should have started many times, right here on our own planet. It could be that intermingled among the seething microbes all around us are some that are so biochemically different they could be descended only from a separate origin. You couldn’t tell by looking, only by delving into their molecular innards and finding something weird enough to rule out a common precursor. The discovery of just a single “alien” microbe under our very noses would be enough to conclude that the universe was indeed teeming with life. 


It would also address a deep philosophical question. Although the pathway from microbes to complex thinking beings like humans may still be a very difficult one, at least we know the mechanism whereby it happens - Darwinian evolution. If microbial life is widespread in the cosmos, we can expect that, at least here and there, sentient beings will evolve. We would then be much closer to answering that age-old puzzle of existence: Are we alone in the universe?