From Uncommon Descent’s The Privileged Planet, Redux
We’ve all heard about the fine-tuning of physical constants–just change them ever so slightly and a different kind of universe emerges. Then, there’s simply our location in our galaxy that allows us to see outwards to the galaxy itself, and beyond. Now, even the radioactivity in the earth’s core seems to be conducive to life.
“What they found is that if the radiogenic heating is more than the Earth’s, the planet can’t permanently sustain a dynamo, as Earth has done. That happens because most of the thorium and uranium end up in the mantle, and too much heat in the mantle acts as an insulator, preventing the molten core from losing heat fast enough to generate the convective motions that produce the magnetic field.
With more radiogenic internal heating, the planet also has much more volcanic activity, which could produce frequent mass extinction events. On the other hand, too little radioactive heat results in no volcanism and a geologically “dead” planet.
“Just by changing this one variable, you sweep through these different scenarios, from geologically dead to Earth-like to extremely volcanic without a dynamo,” Nimmo said, adding that these findings warrant more detailed studies.”
I wonder what the state of the Drake Equation is like these days.
It’s been a while since I thought about it. I have a feeling that it has grown a LOT longer than it used to be!