I wrote this when New Horizons was approaching Pluto, and expected to find new moons and possibly a ring system. So, just as a fun question to hook this post on, I asked, could it find a moon of a moon? Or a moon with rings?

This is a commonly used argument, indeed often taken for granted. We can simulate physics on a computer. So, the argument goes, 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?

Elon Musk says he wants to create a backup of Earth on Mars, and several brilliant people have suggested this should be one of our main objectives for sending humans into space, not only Elon Musk. Perhaps most notably, Stephen Hawking. But being brilliant doesn't mean you are always right in everything you say, or that what you say can't be questioned by anyone else!

There are other good reasons for space settlements - but would any of them be of any value as a "backup" any time in the next few hundred million years? 

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.

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.