You have a great site and I have spent some time looking around and listened to an interview you gave some time back. Thank you for all the great information and code you have freely provided. You're most welcome. Questions for you -

1. Evolution says that life will proliferate under the right circumstances, that life will evolve to conquer new niches and from our experience of the evolution of life on earth life is both varied and abundant in many forms. Why is it then that we are searching for minuscule signs of life in our solar system when we believe the previous sentence to be true? Because science isn't about belief, it's about evidence. No matter how strongly we believe something, we still need evidence. In fact, science works much better if we ignore what we think or hope is true, and focus entirely on gathering evidence without allowing ourselves to be swayed by emotion or belief. If there were any life at all it would be both varied and abundant according to evolution otherwise it would die a slow and perhaps long death. No, that's not true. Life might come into existence elsewhere but remain in a primitive form, as it did here during the first several billion years of Earth's existence — as tiny, hard-to-detect microorganisms, before certain structural changes evolved by chance to allow larger, multicellular organisms to come into existence.

It turns out that, if life exists elsewhere, it's much more likely to be in a primitive but more robust form than much of the life we see around us. This conclusion arises from a simple statistical analysis of the process that leads from prebiotic forms like proteins, to the first simple self-reproducing life forms, to complex multicellular organisms. Such an analysis shows that the base of life's pyramid is much wider (i.e. more probable) than the more delicate and complex organisms at the top.

An argument for this hierarchical view is that, if a huge asteroid crashed into earth, it might wipe out the human race, but single-celled organisms would be hardly affected at all, because their requirements are less strict than ours. In fact, the Toba catastrophe theory posits that an especially powerful volcanic eruption about 70,000 years ago caused an extended global volcanic winter to descend across earth and nearly wiped out the human race. According to this controversial theory, only a small handful of our ancestors survived that episode (as few as 3,000 survivors planetwide), a conclusion supported by careful genetic analysis of living humans. But microorganisms were not wiped out, in fact chances are the global winter provided some new opportunities for creative and rapid bacterial evolution. 2. If we were to detect any signs of life on any exoplanet - what would we do? I don't know what we would do with the information, but it would certainly change our outlook on the topic of life in the universe, our expectations about meeting other intelligent species. Obviously the likelihood of our meeting another intelligent species depends on the likelihood of extraterrestrial life of any kind. At the moment, we just don't know what the probability is for the genesis of life elsewhere — in fact, we don't even know this about life on Earth. We know there's life here now, but we don't know the exact circumstances that produced life, nor what the probabilities are for conditions leading to the first life forms. 3. We assume that if we were to find exoplanets with life we could then investigate further. With our current technology we cannot get there to investigate. It takes us 30+ years just to get to the edge of our own solar system - no human has travelled that long or that far on a single journey. The successful result of finding some sort of life outside our own planet will always remain undecided until we can see it, touch it and examine it. No, this isn't true. We could derive a huge amount of useful information by remote detection — for example, by detecting exoplanets (planets around other stars) likely to harbor life. We could then use remote sensing methods to detect the atmospheric composition of such planets. For example, an exoplanet that showed the atmospheric spectral signature of methane might harbor life, and other detected gases might support or falsify that conclusion or lead to a new theory about atmospheric compositions able to support life.

A new generation of very large telescopes is presently being designed and built to support this kind of remote sensing and investigation. With these new telescopes we may be able to answer questions like (a) how many exoplanets exist in the so-called "Goldilocks zone", the temperature zone where liquid water is possible, and (b) how many of those planets have gravitational and atmospheric compositions suitable for life.

Having created a candidate list of planets that might support life, we could then focus our attention on those targets with a new generation of sophisticated radio and light receivers, to see if there are any more specific signs of life, like broadcasts of alien soap operas. And we could do this without revealing ourselves, to satisfy those who think an aggressive program to reveal our existence might be a bad idea. With your involvement and knowledge of space travel surely we are clutching at straws? Not at all. If we establish that life exists elsewhere in any form, this would support and justify a program to (a) locate other advanced civilizations, then (b) engage in very productive conversations by means of radio or lightwave communications. Without actually visiting alien worlds, we might obtain solutions to some problems that we can't solve on our own, and in turn we might provide solutions to problems that the other civilizations might find hard to solve. Should we not be diverting funds allocated to exoplanet research to finding new science that might get us there? That depends on how you define getting there. If you really believed we would be required to travel to a hypothetical alien planet to derive any benefit from their existence, you wouldn't have written me, you would instead have traveled here and thrown a pebble at my window to start this exchange. But you didn't do that — you were confident that a symbolic, electronic exchange would be productive and more efficient, and you were right.

It's the same with the hypothetical aliens.

Thanks for writing.