Are we alone?

One important question that is raised repeatedly - and is raised in "What I Believe but Cannot Prove" - is the important issue of whether we are alone in the universe.

It is important to distinguish two questions here: is there other life in the universe; and is there other intelligent life in the universe? These are fundamentally different questions, and have different implications. Firstly, what do I mean by "intelligent life"? I would count this as any species who has an awareness of themselves. It therefore implies that they could have an awareness of other beings in the universe.

So, is there other life in the universe? That is, are there other planets where life has independently evolved? The evidence we have from this planet, and the other planets we have investigated in our solar system, does suggest that life in some form is incredibly resilient, and will find a way to survive in the harshest of conditions. It would seem reasonable to surmise that, if life has evolved anywhere, it would find a way to survive. The question then comes down to whether life had evolved elsewhere, whether the miracle and wonder of life is commonplace or rare.

The question of whether there is life elsewhere boils down to whether the core processes that generate life are common or not, are they easy and natural processes that we can expect to occur everywhere or not? This is actually a harder question to answer that it might seem. While the core chemical components of life are relatively common - Carbon, Hydrogen, Oxygen - the complexity of the appropriate combination, the necessity for a few other chemicals, the combination of the compounds to make the required amino-acids, the combination of these to produce basic life: these processes are very complex, very difficult. A single celled organism is, in truth, an incredibly complex piece of chemical engineering. How often is this likely to have happened in the universe?

Of course, the universe is very large, so something that will only occur very infrequently will still occur thousands or millions of times. What is more, we don't know whether the processes that turn a few chemicals into life are common or not. We know that if life can start, it seems to be able to adapt to whatever situation, but does it start easily, or only very occasionally? We don't know, and the answer is crucial. If it is common and easy, then we should expect life in many places. If it is not, then life may be very uncommon, even unique.

The second question, about intelligent life, is a different question. For this to have occurred, it requires not just any life environment to be available, but a very stable one, over a long time. this is needed to enable highly complex life to evolve and settle. Our own planet is very unusual - the large moon jeeps it stable in orbit, the goldilocks zone location makes it ideal for a wide variety of life, the presence of larger planets helps to keep the worst of the space debris away from us. How common is a good, stable environment for highly complex life to evolve in the universe? The unusual nature of our situation, the very strange situation that we find ourselves in would suggest to me that we are unusual. Even if life is common, the idea that it should have developed self-awareness seems to require a very unusual state of affairs - our Earths situation is accepted to be peculiar, unusual, very unexpected. Of course, intelligent life doesn't need a situation exactly like ours, but it does need a stable environment. And we do not know how common stable environments are, however they are created.

In the end, there are tow possibilities: We are alone as intelligent beings in the universe, or; we are not alone as intelligent beings in the universe. We have no idea which of these is the reality, but either option gives us a challenge. To be alone should make us value ourselves far more than we do - to treat life as lightly as we do if we are alone is reckless. To be one of many intelligences in the universe should make us consider just how we might appear to others.

The question may be just an interesting point to muse, but the implications of whichever route we go should challenge us and make us thing.