Leave Earth, or Die!

By Gaz under Ramblings, Technology

Credit for the title of this post goes to Professor Stephen Hawking.

As a Brit in America on Independence Day, I’ve been warned not to go outside incase I get thrown on a fire like Guy Fawkes on Bonfire Night, as is apparently the custom here. Not wishing to be set alight, I decided to hide indoors and post more of my existentialist rantings here instead

The Copernican Principle

In 1514 Nicolaus Copernicus first began discussing his idea that the observed retrograde motion of the planets was because the Earth, along with the other observed planets, were orbiting the Sun — and not vice versa as had been supposed previously. His heliocentric model was the beginning of the end of Ptolemy’s ancient geocentric model of our universe with the Earth at its exact centre, and the church’s anthropocentric doctrines — that the universe was here specifically for the benefit of humans (not to be confused with the anthropic principle). Thus was born, in its original form, the Copernican Principle that states the Earth is not in a central, specially favoured position in space.

More recently, the principle has been further generalised to humans are not observing from a central, specially favoured position in space. That is, just because we are observing from here it doesn’t follow that here is statistically different to any other unremarkable location in the universe. Obviously here is significantly different in light of the fact that it is on the surface of a planet orbiting a star at just the right distance to create the conditions necessary for human-like life to exist… what the modern copernican principle engenders is that there are an astronomically huge number of other places in the universe that are not statistically different to right here, and consequently observing from right here isn’t anything to get excited about.

Live to be 1480!?!

Things get interesting if we apply the same Copernican principle to time: humans are not observing from a central, specially favoured position in time. More precisely, since today isn’t a particularly significant point in my life, I might say that there is a 50% chance that I’m in the middle half of my life; as opposed to the first or last quarter. And, barring catastrophes, being aged 37 today that seems like a pretty good bet. It also gives me a means of predicting how long I’m likely to live in the absence of any other statistical data. At one end of this scale I have 75% of my remaining life ahead of me; that is, I have 3 times more years ahead of me than behind, a generous 111 years to go! Alternatively, if I have 3 times more years behind me than ahead of me, I have only 12 and a bit years left In summary, I can categorically state, given no data other than my current age, that there is a 50% chance I will live between 12 and 111 years more. Big deal! Right?

Well, it’s easy to tighten up if, instead, I say that because I’m not observing from a specially favoured position in time, then there is a 95% chance that I’m in the middle 95% of my life, and not in the first or last 2.5%. And using the same maths, my remaining lifespan is most likely between 1/39th of my current age, and 39 times my current age — a 95% chance of living somewhere between 11 months and 1443 years longer, in fact! Now, that seems pretty dumb in light of all the other statistical data on life expectancy that is available, but it doesn’t make it any less true, and this very principle still comes in handy when the only thing we know about something is how long it has been around so far, and that right now isn’t an especially significant point in time relative to that something.

Even assuming you had never seen anyone drink too much and pass out, it would be pointless to try to work out how much longer I’ll remain conscious when I’ve just started my first Guinness, because it is significant that you are observing my first pint. Perhaps when I’m talking rubbish after 3 pints, you can surmise that 3 pints isn’t a specially favoured point to observe from, and that there is a 95% chance I’ll pass out somewhere between 1/13th of a pint and 57 pints from now; or after 9 pints when I can’t make it to the bar anymore, I’ll most likely pass out between about a quarter of a pint and 27 pints from now. Even with such a frivolous example, it’s plain that the system contains sensible answers within the large range of results it calculates.

Survival of the Human Race

Since we have no concrete statistical data for the survival of intelligent life, what does this imply for the future of our species? For as long as we occupy but a single planet, then we are subject to the same existential risks as every other species that lives, or has lived, here. The entirety of our existence could be erased by an errant comet, sudden climate change, or even a global zombie apocalypse in the wake of burgeoning overpopulation. Modern man has been around for close to 130,000 years. So the Copernican principle as I’ve described above gives a 95% chance that we’ll be around for between 3,300 and 5 million years more.

I’ve mentioned before our need to colonise another planet, and this adds more weight to the argument. Indeed, if we apply the same principle to our future as a space faring society, we might not have long to put it into force. So, with about 45 years of the Space Programme behind us, it’s extremely probable that we have between 1 and 1755 years remaining as a space faring species, if indeed the whole thing isn’t behind us already… It’s arguable, in fact, that the world economy today wouldn’t be able to support the Apollo programme that culminated in Neil Armstrong’s historic moon walk, so in that respect it’s probably a good thing that Kennedy was around to make it happen in the 1960’s. Yes, we could wait for another hundred years for our technology to improve further and make the colonisation all the more attainable, but what if we’re closer to the lower limit of time remaining as a space faring species? And overpopulation, or politics, or economics, or an asteroid brings our space programme to an end sooner rather than later? Bush’s 2004 new vision for the space exploration programme is not a moment too soon in planning to put a man on Mars in less than 23 years.

Considering that ever more prominent scientists backing a plan for colonisation of another planet, and that at least half of the difficulty of a Moon mission (let alone a Mars mission) is the problem of how to get back, I wonder whether the real problem is whether we should come back? With a slew of successful robotic Mars missions under their belt, I think NASA ought to launch a one-way manned mission a few years behind a robotic spearhead that sets up a sustainable artificial habitat in advance. The thing that particularly interests me here though, is the whereabouts of the tipping point for a fully self sufficient colony on Mars. Clearly, genetic diversity needn’t be a problem if a bank of frozen sperm and eggs are deposited (sic) with the first colonists, so the real problem lies in finding sufficient raw materials on Mars itself to sustain a growing colony in the absence of ongoing aid from Earth. And that, to my mind, is just the beginning of providing for the ongoing survival of our species in the event of a global catastrophe. The next problem is how to survive the death of our Sun.

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