Is it worth hunting for aliens?

07 February 2017

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Question

William - Am I right in thinking Goldilocks theory now maintains there are hundreds of parameters, such as the exact diameter of earth, exact gravitation, atmospheric composition, distance from sun, magnetic field and so on which if even slightly different would make life on earth impossible?
If so, doesn't this make the search for exoplanets a bit futile?

Answer

Chris Smith put William's question to Richard Hollinham.

Richard - Nice question Chris. As Chris said the Goldilocks zone which is the area we inhabit, the Earth inhabits. We are the perfect distance from the Sun, we have gravitational stability so Earth doesn’t wobble around on it’s orbit around the Sun thanks to the Moon sitting there orbiting around the Earth. We have a magnetic field and this is very important for life. The magnetic field gives us this magnetosphere which is like a protective magnetic bubble around the Earth which protects us from charged particles from the Sun, stops us from getting zapped. And we’re pretty much the right size. So everything about Earth is great. That doesn’t necessarily mean…

Chris - Not everything.

Richard - Well no. We haven’t got time to go into all the things that are wrong right now. Let’s talk about all the things that are great physically with the Earth. It’s great for life.

That doesn’t necessarily mean that other places aren’t great for life it’s because life might be different there. I’m firmly of the view there is a lot of life out there. It might not be like us and I don’t think it’s going to be intelligent life. But I think if you look at places like hydrothermal vents deep underwater, and very toxic environments, where you can find particularly bacteria, and viruses, other microorganisms that we thought no way life could be there. You just need some source of energy and probably water but not necessarily.

So the argument with Jupiter’s moons which may have liquid water, energy there won’t come from the Sun, energy there will come from the gravity of Jupiter. So you’re looking at all these places that could have life but it won’t necessarily be us.

Chris - I was very fortunate to go down one of the world’s deepest gold mines in south Africa. And, in fact, in these operations there are microbiologists working because there are seeps of water and you can prove chemically that the water has been cut off from the rest of the world for millions of years, maybe 100 million years plus. You can tell that from the chemistry of the water. And yet when you look in this water which, in some cases is 60 degrees centigrade, you can find it’s thriving with bacterial life. So people said “well where do they come from?”

When scientists unpicked this, and this was a paper in Science about ten years ago, what they find is that there is uranium present in the ore. The radium is spitting out radiation, and the radiation is doing things to water molecules and giving them some energy. The water molecules then attack minerals in the rocks and release them for these microbes to live on, and the first layer of microbes eat those and then other microbes eat those first microbes, and you’ve got this whole ecosystem growing powered by radiation. So once people found that they said well look, it’s not so unlikely that you could have this somewhere else in our solar system, in a very inhospitable place but it’s got a nice warm interior because it’s radioactive and there’s life there.

Richard - Yeah. We can’t answer the fundamental question of how life gets there in the first place, but there does seem to be life in the most unlikely places.

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