Robert Inventor

The way this is usually presented is - that we can simulate physics on a computer. So what is to stop us eventually simulating your whole body including your brain? And if so, is it not just a matter of time, and increasing computer power before we have exact simulations of humans as computer programs? Programs whose behaviour is indistinguishable from humans?This is a staple of many science fiction stories of course. But some logicians, philosophers and physicists think there are flaws in this argument.We know the laws of physics are incomplete. Could there be physical processes which for some reason are impossible to simulate using a computer program? And could processes like that go on in a human being? This is what Roger Penrose thinks.

The brain is based on physics, and we can simulate physics on a computer, so what is to stop us eventually simulating human beings in a computer, your whole body including your brain? Many researchers, and science fiction writers have come to the conclusion that it is just a matter of time, and increasing computer power before we can do this.However - there are some gaps in this reasoning. Are the laws of physics as we know them complete? Could there be laws physics that we can't simulate using a computer program? 

Have you ever wondered if any spaceship could ever travel through the sun with future technology? What if it is as big as Mercury or larger? Nothing material will work that we know of.  The sun's temperature of 26 million degrees is far too hot, and the most refractory substances we know of melt at a few thousand degrees. It seems a hopeless task. But there are a few things to explore, so let's look a bit more closely. (You can download this article as a kindle ebook)

Many of us care deeply about the possibility of tigers, lemurs and such like becoming extinct in the wild. I'd like to suggest that we care as much about the possibility of microbes on Mars and elsewhere in our solar system becoming extinct through human activities.

Many people care deeply about the possibility of tigers, lemurs and such like becoming extinct in the wild. I'd like to suggest we care as much about the possibility of microbes on Mars and elsewhere in our solar system becoming extinct through human activities. So what's so special about microbes on Mars? Well first, the uniqueness. Tigers are closely related to cats. They are wonderful and remarkable creatures - and would be a tremendous shame to lose them - but basically it's the familiar tabby in another guise.

Many people care deeply about the possibility of tigers, lemurs and such like becoming extinct in the wild. I'd like to suggest we care as much about the possibility of microbes on Mars becoming extinct. And more so.

Where should we go, on Mars, to look for droplets and streaks of present day liquid water? You may have heard of the "warm seasonal flows", and the recent "swimming pools of bacteria". However,  there are several other promising ideas for habitats such as the "Flow like features", the advancing sand dunes bioreactor, and possibilities for life using the humidity of the night time air on Mars. It's an exciting field with many new discoveries and ideas every year, and it is hard to keep up with the developments.

This is an exciting field which developed over just the last six years or so. There are many academic papers - but I haven't been able to find a good overview of the field in non technical language. So, let's do that. I'm drawing heavily on Nilton Renno's technical overview from last year, together with more recent results.Let's start with the Flow Like Features associated with the dark dune spots in the southern polar region. These are lesswell known than some of the other candidates but rather interesting, as the best explanation involves melt water at 0°C, warm for liquid water on Mars, also (at its source) pure water, unusually for Mars.

NASA proposes to return a sample from Mars in the 1920s and recently announced details of the successor for Curiosity which will drill and cache samples for return. But is this the best approach in the search for life on Mars? What about searching "in situ" directly on Mars itself?

This idea goes back in 1967. James Lovelock, originator of the Gaia hypothesis, found a way to use a planetary atmosphere to detect life. He suggested that we look for simultaneous presence of pairs of gases like oxygen and methane that react together. We can also search for gases such as oxygen above  levels expected from abiotic processes.As  far as we can see, Mars atmosphere seems to be close to equilibrium in this way. So when Viking I and II landed there in 1976, and found a barren desert-like surface, it seemed natural to conclude that there is no life on Mars.

This is something James Lovelock, author of the Gaia Hypothesis, predicted, way back in 1967. He said that Mars is lifeless, based on nothing more elaborate than the simple observation that it's atmosphere is in chemical equilibrium.. Nine years later, Viking I and II found a barren desert-like surface in 1976, which seemed to confirm his conclusions.

I thought I'd post this because there are many who haven't followed the latest findings, who still think that present day life on the surface of Mars is absolutely impossible because of UV light, ionizing radiation, and perchlorates, and because the atmosphere is in almost perfect chemical equilibrium. That is indeed what most scientists believed, prior to about 2008. But it is now generally agreed in the field that if there do turn out to be nutritious warm and wet habitats on the surface of Mars, they will be habitable.