So are we doomed? It’s not looking good, models suggest
THE Drake Equation is gradually filling out, and it’s looking good for the existence of life, the rise of intelligence and the likely number of civilisations elsewhere in the universe.
There’s even reason to hope that some highenergy technological civilisations successfully pass through the energyenvironment bottleneck that our own planetary civilisation is now entering. But not all of them.
The Drake Equation was written by American radio astronomer Frank Drake in 1961 to estimate how many hightech civilisations there were in the galaxy. It had seven factors, but they were all empty.
The first three factors were: what is the average rate of star formation in our galaxy; how many of those stars have planets; and what proportion of those planets can potentially support life? We know the answers now, and they are pretty encouraging.
There’s around one new star annually, most stars have planets, and about one star in five has a planet with liquid water on the surface. That means that around 100 billion planets in this galaxy alone can support life, but that’s just a start.
There are about 100 billion galaxies in the universe, so the total number of planets potentially able to support life is about 10,000,000,000,000,000,000,000
(10 billion trillion).
What Adam Frank has done, in his recent book, Light of the Stars: Alien Worlds and the Fate
of the Earth, is to point out that there must therefore have been a lot of ‘‘exocivilisations’’. Make your assumptions about first life and then intelligence emerging on any given planet as pessimistic as you like, and there will still be a lot.
What Frank really wants to know is how many of those civilisations made it through the bottleneck — and for that he doesn’t need to know anything specific about those unknown exocivilisations. He only needs to know that all civilisations use large amounts of energy, and that there is a strictly limited number of ways that a ‘‘young’’ technological civilisation like ours can access energy.
There will be fossil fuels on some planets, but not on others. There’s hydro, wind and tides. There’s solar, geothermal and nuclear. That’s it. Using energy always produces waste, but some of these modes produce far less heat, carbondioxide and toxic chemicals than others.
So put different original mixes of these energy sources into your experimental models, put in different planetary conditions as well, and run a few thousand of these models through your computer.
It turns out that most of the models see runaway population growth, followed at a distance by growing pressures on the planet’s environment that lowers the ‘‘population carrying capacity’’.
At some point the alarmed population switches to lowerimpact energy sources. There is still a steep dieback (up to 70%) in the population, but then a steady state emerges and the civilisation survives.
In other models, the planet’s people (creatures? beings?) delay switching the energy sources for too long, and the late movers don’t make it. The population starts to fall, then appears to stabilise for a while, then rushes downward to extinction. Nobody saw that one coming, but that’s what the models are telling us.
So where does our own planetary civilisation fall on this spectrum of possible behaviours? I don’t know, but this just in.
Oil production is at an alltime high of 100 million barrels a day, and the Organisation of PetroleumExporting Countries has just predicted that it will reach 112 mbd in the next 20 years. That’s definitely the wrong direction.