What Makes the Earth Rare

What is it about the Earth that has allowed life to continue for such long periods of time? The most important factor is plate tectonics. 

When we thought up the Rare Earth Hypothesis, it was simply taking a look at what happened on this planet that allowed us to have multi-cellularity.  Part of it was that we had conditions allowing habitability for billions of years.  It took a long time to get to something as simple as a two-celled creature. A long time.  


How do you get a long time?  You do it because systems of temperature, systems of oxygen, systems of all the gasses and the carbon movement remains stable.  If you get too hot, too cold and only a little bit too hot and a little bit too cold in a planetary sense, you can kiss it all good-bye. 

So, what is it about the Earth that allowed things to continue for such long periods of time?  The most important factor is plate tectonics.  This is the movement of the surface of the Earth over the top of a mobile, softer rock substrate beneath it.  So, the continents skate around like bumper cars.  Part of that process is a continental and ocean recycling.  And that recycling system is an absolutely necessity to keep a long term temperature constancy.  We have this feedback system, a thermostat system.  What makes the earth warmer is carbon dioxide, what makes the earth cooler, interestingly enough, is the removal of that carbon dioxide.  Volcanoes put it in the air, but weathering removes it.  If you take a granite, or any rock that had a volcanic material in it and let it chemically weather, one of the byproducts takes Co2 out of the atmosphere.  The warmer it gets, the faster that process works. 

So, the warmer it gets the faster the breakdown removes Co2.  If you get down to an area, or a level at which you can no longer chemically weather, the volcanoes refill you up.  Now that bang-bang feedback system has been in service for over 3 ½ billion years or more.  That has kept us at a stable temperature.  How often does a planet have plate tectonics?  By looking at the nature of the rock, we barely have it.  If you want to think about the end of the world, the end of the world is going to happen when the friction co-efficiency over-exceeds the type of rock we have, and we no longer have these subduction zones. 

The end of the world is also going to be when our core - we have this liquid molten core - it’s going to freeze because the Earth is slowly dying and cooling.  When that freezes, we lose our magnetic field.  So we also have consequences for plate tectonics. So, those two things are geologically produced.  How often do you find both of them on the same planet?  Theoretical studies say, not very often.  

In Their Own Words is recorded in Big Think's studio.

Image courtesy of Shutterstock

​There are two kinds of failure – but only one is honorable

Malcolm Gladwell teaches "Get over yourself and get to work" for Big Think Edge.

Big Think Edge
  • Learn to recognize failure and know the big difference between panicking and choking.
  • At Big Think Edge, Malcolm Gladwell teaches how to check your inner critic and get clear on what failure is.
  • Subscribe to Big Think Edge before we launch on March 30 to get 20% off monthly and annual memberships.
Keep reading Show less

The colossal problem with universal basic income

Here's why universal basic income will hurt the 99%, and make the 1% even richer.

Videos
  • Universal basic income is a band-aid solution that will not solve wealth inequality, says Rushkoff.
  • Funneling money to the 99% perpetuates their roles as consumers, pumping money straight back up to the 1% at the top of the pyramid.
  • Rushkoff suggests universal basic assets instead, so that the people at the bottom of the pyramid can own some means of production and participate in the profits of mega-rich companies.
Keep reading Show less

Top vets urge dog lovers to stop buying pugs and bulldogs

Pugs and bulldogs are incredibly trendy, but experts have massive animal welfare concerns about these genetically manipulated breeds. 

'No nose, no thermoregulation, no health, no welfare.' Photo by terriermandotcom.blogspot.com
popular

Pugs, Frenchies, boxers, shih-tzus and other flat-faced dog breeds have been trending for at least the last decade, thanks to higher visibility (usually in a celebrity's handbag), an increase in city living (smaller dogs for smaller homes), and possibly even the fine acting of Frank the Pug in 1997's Men in Black. We're not ruling it out. These small, specialty pure breeds are seen as the pinnacle of cuteness – they have friendly personalities, endearing odd looks, and are perfect for Stranger Things video montages.

Keep reading Show less

This is the best (and simplest) world map of religions

Both panoramic and detailed, this infographic manages to show both the size and distribution of world religions.

(c) CLO / Carrie Osgood
Strange Maps
  • At a glance, this map shows both the size and distribution of world religions.
  • See how religions mix at both national and regional level.
  • There's one country in the Americas without a Christian majority – which?
Keep reading Show less