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Michael Strauss: are Earth-like planets common in the universe?

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Christianity and the progress of science
Christianity and the progress of science

Physicist Michael Strauss is one of my favorite speakers and scholars – he has a real love of experimental science which I find lacking in many Christian philosophers who seem to treat science (as opposed to naturalism) as the enemy.

Here is his latest blog post:

When scientists say that an Earth-like planet may have been discovered, they actually mean one of three things. Either (1) the planet is in such an orbit around its central star that allows the temperature on the planet to possibly harbor liquid water, or (2) the planet is about the same size as the earth, or (3) the planet is solid and rocky rather than gaseous. Of course any one of these criteria, or even all three, does not actually give us a true Earth-like planet. We know that our moon is in the correct location to contain liquid water, but it is not “Earth-like.” We know Venus is about the size of the earth, but it is not “Earth-like.” We know that Mercury is rocky and not gaseous, but it is not “Earth-like.” So none of these criteria really give an Earth-like planet. Headlines and sound-bites are not meant to be precise but to draw attention, and it is much more exciting to proclaim an “Earth-like” planet has been found rather than a “Venus-like” planet (if even that could be claimed).

[…]An enlightening book on this subject is Rare Earth: Why Complex Life Is Uncommon in the Universe by Peter D. Ward and Donald Brownlee, published in 2000. One of my favorite chapters in the book is titled “The Surprising Importance of Plate Tectonics” which documents why plate tectonics is required in order for complex life to survive. Having lived 23 years of my life in California, I am well acquainted with the consequences of plate tectonics, but had no idea that such activity was crucial for my survival. Ward and Brownlee document how plate tectonics not only forms and maintains continents, but promotes biological diversity, regulates global temperature, and helps maintain a planetary magnetic field. They write, “It may be that plate tectonics is the central requirement for life on a planet and that it is necessary for keeping a world supplied with water,” (p. 220).

The astrophysicist Hugh Ross has done a rough estimate of the probability of finding a single planet that could support even simple unicellular life for a sustained period of time. Including correlations and longevity factors, and assuming there are 10 billion trillion planets in the visible universe, he concludes that the probability of finding a single planet that could support unicellular life for a prolonged period of time is 1 in 10556, (see Part B of this document). If this informed estimate is even close to being correct, then there are no other planets in the visible universe that can support life.

Previously, I blogged about a few of the minimum requirements that a planet must satisfy in order to support complex life.

Here they are:

  • a solar system with a single massive Sun than can serve as a long-lived, stable source of energy
  • a terrestrial planet (non-gaseous)
  • the planet must be the right distance from the sun in order to preserve liquid water at the surface – if it’s too close, the water is burnt off in a runaway greenhouse effect, if it’s too far, the water is permanently frozen in a runaway glaciation
  • the planet has to be far enough from the star to avoid tidal locking and solar flares
  • the solar system must be placed at the right place in the galaxy – not too near dangerous radiation, but close enough to other stars to be able to absorb heavy elements after neighboring stars die
  • a moon of sufficient mass to stabilize the tilt of the planet’s rotation
  • plate tectonics
  • an oxygen-rich atmosphere
  • a sweeper planet to deflect comets, etc.
  • planetary neighbors must have non-eccentric orbits
  • planet mass must be enough to retain an atmosphere, but not so massive to cause a greenhouse effect

That’s a lot of characteristics that need to be present. When you calculate the probabilities of each one and then multiply them (product rule) to get the odds of getting a planet with ALL of them present, you get a number far smaller than the maximum number of possible life sites in the universe. We are alone.

News

New study: model of 700 quintillion terrestrial exoplanets suggests Earth is special

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The Circumstellar Habitable Zone, where liquid water could potentially exist
The Circumstellar Habitable Zone, where liquid water could potentially exist

This is from Scientific American. (H/T William)

Excerpt:

More than 400 years ago Renaissance scientist Nicolaus Copernicus reduced us to near nothingness by showing that our planet is not the center of the solar system. With every subsequent scientific revolution, most other privileged positions in the universe humans might have held dear have been further degraded, revealing the cold truth that our species is the smallest of specks on a speck of a planet, cosmologically speaking. A new calculation of exoplanets suggests that Earth is just one out of a likely 700 million trillion terrestrial planets in the entire observable universe. But the average age of these planets—well above Earth’s age—and their typical locations—in galaxies vastly unlike the Milky Way—just might turn the Copernican principle on its head.

Astronomer Erik Zackrisson from Uppsala University and his colleagues created a cosmic compendium of all the terrestrial exoplanets likely to exist throughout the observable universe, based on the rocky worlds astronomers have found so far. In a powerful computer simulation, they first created their own mini universe containing models of the earliest galaxies. Then they unleashed the laws of physics—as close as scientists understand them—that describe how galaxies grow, how stars evolve and how planets come to be. Finally, they fast-forwarded through 13.8 billion years of cosmic history. Their results, published to the preprint server arXiv (pdf) and submitted to The Astrophysical Journal, provide a tantalizing trove of probable exoplanet statistics that helps astronomers understand our place in the universe.

Discover magazine, which is all in for Darwinism and aliens everywhere, says this about the study:

Zackrisson found that Earth appears to have been dealt a fairly lucky hand. In a galaxy like the Milky Way, for example, most of the planets Zackrisson’s model generated looked very different than Earth — they were larger, older and very unlikely to support life.

[…]Zackrisson’s work suggests an alternative to the commonly held assumption that planets similar to Earth must exist, based on the sheer number of planets out there.

[…]One of the most fundamental requirements for a planet to sustain life is to orbit in the “habitable zone” of a star — the “Goldilocks” region where the temperature is just right and liquid water can exist. Astronomers have, to this point, discovered around 30 exoplanets in the habitable zones of stars. Simply extrapolating that figure based on the known number of stars suggests that there should be about 50 billion such planets in the Milky Way alone. Probability seems to dictate that Earth-twins are out there somewhere.

But according to Zackrisson, most planets in the universe shouldn’t look like Earth. His model indicates that Earth’s existence presents a mild statistical anomaly in the multiplicity of planets. Most of the worlds predicted by his model exist in galaxies larger than the Milky Way and orbit stars with different compositions — an important factor in determining a planet’s characteristics. His research indicates that, from a purely statistical standpoint, Earth perhaps shouldn’t exist.

Time for me to list out some of the things that are required for a galaxy, solar system and planet to support complex embodied life. Not just life as we know it, but life of any conceivable kind given these laws of physics.

  • a solar system with a single massive Sun than can serve as a long-lived, stable source of energy
  • a terrestrial planet (non-gaseous)
  • the planet must be the right distance from the sun in order to preserve liquid water at the surface – if it’s too close, the water is burnt off in a runaway greenhouse effect, if it’s too far, the water is permanently frozen in a runaway glaciation
  • the solar system must be placed at the right place in the galaxy – not too near dangerous radiation, but close enough to other stars to be able to absorb heavy elements after neighboring stars die
  • a moon of sufficient mass to stabilize the tilt of the planet’s rotation
  • plate tectonics
  • an oxygen-rich atmosphere
  • a sweeper planet to deflect comets, etc.
  • planetary neighbors must have non-eccentric orbits

It’s not easy to make a planet that supports life. For those who are interested in reaching out to God, he has left us an abundance of evidence for his existence – and his attention to detail.

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Polemics

The media reported that TRAPPIST-1 planets were “Earth-like”, but were they?

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Christianity and the progress of science
Christianity and the progress of science

My assumption whenever I read these headlines from the naturalist mainstream media is that they are just scientific illiterates pushing a science fiction agenda. Naturalists believe that no intelligent designer was required in order to create a planet, a solar system and a galaxy fine-tuned for complex embodied life. The mainstream media tries to help naturalists by trumpeting that make planets that support life look common, so that no designer is needed.

Recently, there was a story about some planets that the mainstream media called “Earth-like”. But were they really Earth-like?

Evolution News reports: (links removed)

Do you recall the hubbub only one month ago about TRAPPIST-1, a dim red dwarf star some 40 light years from Earth? This star has seven planet, three of which, roughly Earth-sized, were announced as being potentially habitable. This led to excited speculation about alien evolution:

  • “Scientists find three new planets where life could have evolved” (Sky News)
  • “Nasa discovers new solar system where life may have evolved on three planets” (The Telegraph)
  • “Nasa’s ‘holy grail’: Entire new solar system that could support alien life discovered” (The Independent)
  • “Seven Alien ‘Earths’ Found Orbiting Nearby Star” (National Geographic)

Well, not so fast. Much of the breathlessness about the system stemmed from a tho

roughly imaginative artist’s rendering courtesy of NASA. The planets are designated by letters, b through h. The middle three planets are depicted as rather inviting, with what appear to be pleasing Earth-like oceans.

Today, the TRAPPIST-1 bubble looks to have popped, with 3D computer climate modeling showing major problems with the system. According to Eric T. Wolf of the University of Colorado’s Laboratory for Atmospheric and Space Physics, the inner three planets would be barren, the outer three frozen. And the middle, planet e? In NASA’s rendering, it looks the most Earth-like. However, in a system like this centering on a dim red dwarf, planet e would need to have been stocked, to start, with seven times the volume of Earth’s oceans.

roughly imaginative artist’s rendering courtesy of NASA. The planets are designated by letters, b through h. The middle three planets are depicted as rather inviting, with what appear to be pleasing Earth-like oceans.

Today, the TRAPPIST-1 bubble looks to have popped, with 3D computer climate modeling showing major problems with the system. According to Eric T. Wolf of the University of Colorado’s Laboratory for Atmospheric and Space Physics, the inner three planets would be barren, the outer three frozen. And the middle, planet e? In NASA’s rendering, it looks the most Earth-like. However, in a system like this centering on a dim red dwarf, planet e would need to have been stocked, to start, with seven times the volume of Earth’s oceans.

Let’s review what’s needed for a planet to support life, so that when these stories come out, we can recognize how many “Earth-like” qualities required for life are not mentioned.

Previously, I blogged about a few of the minimum requirements that a planet must satisfy in order to support complex life.

Here they are:

  • a solar system with a single massive Sun than can serve as a long-lived, stable source of energy
  • a terrestrial planet (non-gaseous)
  • the planet must be the right distance from the sun in order to preserve liquid water at the surface – if it’s too close, the water is burnt off in a runaway greenhouse effect, if it’s too far, the water is permanently frozen in a runaway glaciation
  • the planet has to be far enough from the star to avoid tidal locking and solar flares
  • the solar system must be placed at the right place in the galaxy – not too near dangerous radiation, but close enough to other stars to be able to absorb heavy elements after neighboring stars die
  • a moon of sufficient mass to stabilize the tilt of the planet’s rotation
  • plate tectonics
  • an oxygen-rich atmosphere
  • a sweeper planet to deflect comets, etc.
  • planetary neighbors must have non-eccentric orbits
  • planet mass must be enough to retain an atmosphere, but not so massive to cause a greenhouse effect

Now what happens if we disregard all of those characteristics, and just classify an Earth-like planet as one which is the same size and receives the same amount of radiation from its star? Well, then you end up labeling a whole bunch of planets as “Earth-like” that really don’t permit life.