The universe is a fairly large place, as Carl Sagan once remarked. "If it is only us, it seems like a terrible waste of space."
The Drake equation gradually fills in and it looks good for the existence of life, the rise of intelligence and the likely number of civilizations elsewhere in the universe.
There is even reason to hope that some high-energy technological civilizations successfully pass the energy-environment bottleneck that our own planetary civilization is now entering. But there are not many who get through the bottleneck without suffering major losses, and a lot is just going to happen.
The Drake equation was written by the American radio astronomer Frank Drake in 1961 to estimate how many high-tech civilizations there were in the Melkweg. It had seven factors, but they were all empty.
The first three factors, all uncertain in 1961, were: what is the average rate of star formation in our galaxy; how many of those stars have planets; and which part of those planets can potentially support life? We know the answers now, and they are pretty encouraging.
Every year there is about one new star, most stars have planets and about one star in five accommodates one or more planets with liquid water on the surface. That means that there are probably only about one hundred billion planets in this galaxy that can support life, but that is only a beginning.
As Douglas Adams indicated The Hitch-Hiker's Guide to the Galaxy"The room is big, really big, you just will not believe how huge, huge, mind-boggling it is."
The Hubble telescope has revealed about a hundred billion galaxies in the universe. Total number of potentially life-supporting planets? About 10,000,000,000,000,000,000,000 (ten billion trillion).
Drake & # 39; s remaining factors are still unknown quantities. The only two of interest to Adam Frank – for all he wants to know is how many non-human civilizations have ever existed anywhere in the universe – is what fraction of potentially life-sustaining planets is actually developing life? and which part of those planets continues to develop intelligent life.
What Adam Frank did in his recent book, Light of the Stars: Alien Worlds and the Fate of the Earthis to point out that there are so many & # 39; exo-civilizations & # 39; must have been. Make assumptions about the first life and then the intelligence that comes on a random planet, as pessimistic as you want, and there will still be many.
Perhaps not billions or even millions, but even if you assume that only one life-supporting planet in a million trillion has ever supported a civilization, there would have been ten thousand of it. That is big enough for a statistical sample, and what Frank really wants to do is to activate the figures and get a grip on how many of those civilizations would have come through the bottleneck.
He does not need to know anything specific about those unknown exo-civilizations. He only needs to know that all civilizations use large amounts of energy and that there is a strictly limited number of ways in which a technological & # 39; young & # 39; civilization if ours has access to energy.
There are fossil fuels, if your planet had a Carboniferous era or burned biomaterials only if it was not. There is hydropower, wind and tides. There is solar, geothermal and nuclear. That is it. The use of energy always produces waste, but some of these modes produce much less heat, carbon dioxide and toxic chemicals than others.
So place different original mixes of these energy sources in your experimental models, set them in different planetary conditions (some planets get closer to their suns, a bit further away) and run a few thousand of these models via your computer.
It turns out that most models see a runaway population increase, followed by remote pressure on the planet's environment that the population's ability to pay & # 39; lowers.
At some point, the alarmed population switches to energy sources with a lower impact. There is still a steep decline (up to 70 percent) in the population, but then a stable state arises and civilization survives.
In other models, the people of the planet (beings?) Slow down the energy sources for too long. They all switch over eventually, but the laggards still do not get it. The population begins to fall, then seems to stabilize for a while and then runs down to extinction. Nobody saw it coming, but it is what the models tell us.
There is still a huge amount of research to be done in this new domain, but it is time to ask where our own planetary civilization falls on this spectrum of possible behavior.
I do not know, but this is just inside. Oil production is at the highest point ever of 100 million barrels per day, and the Organization of Oil-exporting Countries predicts that it will reach 112 mbd in the next 20 years. That is the wrong direction.