Recently, I picked up the audio book version of “The Privileged Planet”, which is a book by philosopher / economist Jay Richards and astronomer Guillermo Gonzalez. This book is different from books about the origin of the universe and cosmic fine-tuning. It talks about what it takes to make a habitable planet. And it talks about how the habitable places in the universe are also the best places to make scientific discoveries.
Christian scholar Jay Richards was interviewed by Brian Auten of Apologetics 315.
The Earth’s Atmospheric Conditions Are Favorable to Life:
The surface gravity of Earth is critical to its ability to retain an atmosphere friendly to life. If Earth’s gravity were stronger, our atmosphere would contain too much methane and ammonia. If our planet’s gravity were weaker, Earth wouldn’t be able to retain enough water. As it is, Earth’s atmosphere has a finely calibrated ratio of oxygen to nitrogen—just enough carbon dioxide and adequate water vapor levels to promote advanced life, allow photosynthesis (without an excessive greenhouse effect), and to allow for sufficient rainfall.
Ok, that’s very good.
Now here is one from me… well, it’s from Science Daily, but I found it. Actually, ECM found it. But he told me.
They suggest that the size and location of an asteroid belt, shaped by the evolution of the Sun’s protoplanetary disk and by the gravitational influence of a nearby giant Jupiter-like planet, may determine whether complex life will evolve on an Earth-like planet.
This might sound surprising because asteroids are considered a nuisance due to their potential to impact Earth and trigger mass extinctions. But an emerging view proposes that asteroid collisions with planets may provide a boost to the birth and evolution of complex life.
Asteroids may have delivered water and organic compounds to the early Earth. According to the theory of punctuated equilibrium, occasional asteroid impacts might accelerate the rate of biological evolution by disrupting a planet’s environment to the point where species must try new adaptation strategies.
The astronomers based their conclusion on an analysis of theoretical models and archival observations of extrasolar Jupiter-sized planets and debris disks around young stars. “Our study shows that only a tiny fraction of planetary systems observed to date seem to have giant planets in the right location to produce an asteroid belt of the appropriate size, offering the potential for life on a nearby rocky planet,” said Martin, the study’s lead author. “Our study suggests that our solar system may be rather special.”
So, that’s 5 ways that the Earth and our solar system are fine-tuned to be habitable for complex, embodied minds. Somebody is looking out for you, so be thankful and recognize.
I found an interview with Peter Ward (atheist) and Donald Brownlee (agnostic) discussing astrobiology in Forbes magazine. They were asked about how important plate tectonics are for a planet to be able to support complex life.
Astrobiologists often cite the sheer numbers of stars and galaxies as evidence that complex life elsewhere must surely have evolved somewhere. But is probability enough?
Without a moon, we don’t have any idea of how commonly a planet could have the long-term stability needed for complex life. Until we “get” that, going to the sheer numbers argument is useless. Without that moon-forming collision, we wouldn’t have plate tectonics. Without plate tectonics, we might have microbes but we’d never get to animals.
What about the rarity of earth’s crustal dichotomy of oceans and continents?
If you can’t make granite, you’re not going to have continents. But granite formation is a consequence of our moon-forming collision. That scrambled the entire density of our crust. Mars doesn’t have granite; all it’s got is this volcanic basalt. To build granite you need a planetary subduction [or plate tectonic] process.
In triggering complex life, how important were plate tectonics’ role in the continual recycling of earth’s atmosphere?
It’s this recycling that allows for a very rich planetary atmosphere with an extended life. Photosynthesis gets you oxygen, but how do you get enough photosynthesis to get oxygen at 10 to 20 percent? You’ve got to have a shoreline next to a rich sea with rocks eroding into it in order to provide the nitrogen and phosphates for [plant] photosynthesis.
This article from Astrobiology explains more about the importance of plate tectonics.
Plate tectonics is the process of continents on the Earth drifting and colliding, rock grinding and scraping, mountain ranges being formed, and earthquakes tearing land apart. It makes our world dynamic and ever-changing. But should it factor into our search for life elsewhere in the universe?
Tilman Spohn believes so. As director of the German Space Research Centre Institute of Planetary Research, and chairman of ESA’s scientific advisory committee, he studies worlds beyond our Earth. When looking into the relationship between habitability and plate tectonics, some fascinating possibilities emerged.
It is thought that the best places to search for life in the Universe are on planets situated in “habitable zones” around other stars. These are orbital paths where the temperature is suitable for liquid water; not so close to the star that it boils away, and not so far that it freezes. Spohn believes that this view may be outdated. He elaborates, “you could have habitats outside those, for instance in the oceans beneath ice covers on the Galilean satellites, like Europa. But not every icy satellite would be habitable. Take Ganymede, where the ocean is trapped between two layers of ice. You are missing a fresh supply of nutrition and energy.”
So planets and moons that lie beyond habitable zones could host life, so long as the habitat, such as an ocean, is not isolated. It needs access to the key ingredients of life, including hydrogen, oxygen, nitrogen, phosphorous and sulphur. These elements support the basic chemistry of life as we know it, and the material, Spohn argues, must be regularly replenished. Nature’s method of achieving this on the Earth appears to be plate tectonics.
Spohn found that the further he delved into the issue, the more important plate tectonics seemed to be for life. For example, it is believed that life developed by moving from the ocean to the kind of strong and stable rock formations that are the result of tectonic action. Plate tectonics is also involved in the generation of a magnetic field by convection of Earth’s partially molten core. This magnetic field protects life on Earth by deflecting the solar wind. Not only would an unimpeded solar wind erode our planet’s atmosphere, but it also carries highly energetic particles that could damage DNA.
Another factor is the recycling of carbon, which is needed to stabilize the temperature here on Earth. Spohn explains, “plate tectonics is known to recycle carbon that is washed out of the atmosphere and digested by bacteria in the soil into the interior of the planet from where it can be outcast through volcanic activity. Now, if you have a planet without plate tectonics, you may have parts of this cycle, but it is broken because you do not have the recycling link.”
It has also been speculated that the lack of tectonic action on Venus contributed to its runaway greenhouse effect, which resulted in the immense temperatures it has today.
Most planets don’t have a moon as massive as ours is, and the collision that formed the moon is very fine-tuned for life. This is just one of the many factors that needs to be present in order to have a planet that supports complex, carbon-based life.
If you want to learn more about this data, I recommend watching “The Privileged Planet” DVD, and someone posted it on YouTube:
If you haven’t seen it, and have 90 minutes, this is time well-spent.