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Harvard astrophysicist backs the Rare Earth hypothesis

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What is the Rare Earth hypothesis?

It’s the thesis of a recent book written by two scientists at the University of Washington.

Here’s the blurb:

What determines whether complex life will arise on a planet? How frequent is life in the Universe?

In this exciting new book, distinguished paleontologist Peter D. Ward and noted astronomer Donald Brownlee team up to give us a fascinating synthesis of what’s now known about the rise of life on Earth and how it sheds light on possibilities for organic life forms elsewhere in the Universe.

Life, Ward and Brownlee assert, is paradoxically both very common and almost nowhere. The conditions that foster the beginnings of life in our galaxy are plentiful. But contrary to the usual assumption that if alien life exists, it’s bound to be intelligent, the authors contend that the kind of complex life we find on Earth is unlikely to exist anywhere else; indeed it is probably unique to our planet.

With broad expertise and wonderful descriptive imagery, the authors give us a compelling argument, a splendid introduction to the emerging field of astrobiology, and a lively discussion of the remarkable findings that are being generated by new research. We learn not only about the extraordinary creatures living in conditions once though inimical to life and the latest evidence of early life on Earth, but also about the discoveries of extrasolar planets, the parts Jupiter and the Moon have played in our survival, and even the crucial role of continental drift in our existence.

Insightful, well-written, and at the cutting edge of modern scientific investigation, Rare Earth should interest anyone who wants to know about life elsewhere and gain a fresh perspective on life at home which, if the authors are right, is even more precious than we may ever have imagined.

And here’s a review by Library Journal:

“Renowned paleontologist Ward (Univ. of Washington), who has authored numerous books and articles, and Brownlee, a noted astronomer who has also researched extraterrestrial materials, combine their interests, research, and collaborative thoughts to present a startling new hypothesis: bacterial life forms may be in many galaxies, but complex life forms, like those that have evolved on Earth, are rare in the universe. Ward and Brownlee attribute Earth’s evolutionary achievements to the following critical factors: our optimal distance from the sun, the positive effects of the moon’s gravity on our climate, plate tectonics and continental drift, the right types of metals and elements, ample liquid water, maintainance of the correct amount of internal heat to keep surface temperatures within a habitable range, and a gaseous planet the size of Jupiter to shield Earth from catastrophic meteoric bombardment. Arguing that complex life is a rare event in the universe, this compelling book magnifies the significance — and tragedy — of species extinction. Highly recommended for all public and academic libraries.”

Note that Peter Ward is a militant atheist (he has debated against Stephen C. Meyer), and Donald Brownlee is an agnostic. These are not Christians, nor are they even theists. However, I have the book, I have read the book, and I recommend the book. I usually have this book on my shelf at work for show-and-tell.

Now for the latest news about the hypothesis of the book. (H/T Brian Auten of Apologetics 315)

There are always going to be optimistic predictions by scientists who need to attract research funding, but those are hopes and speculations. The data we have today says Earth is rare. The number of conditions required for complex life of any kind is too high for us to be optimistic about alien life in this galaxy, at least. And as the number of requirements for life roll in, the odds of finding alien life that can contact us get slimmer and slimmer.

From the UK Daily Mail. (H/T Peter S. Williams)

Excerpt:

Dr Howard Smith, a senior astrophysicist at Harvard University, believes there is very little hope of discovering aliens and, even if we did, it would be almost impossible to make contact.

So far astronomers have discovered a total of 500 planets in distant solar systems – known as extrasolar systems – although they believe billions of others exist.

But Dr Smith points out that many of these planets are either too close to their sun or too far away, meaning their surface temperatures are so extreme they could not support life.

Others have unusual orbits which cause vast temperature variations making it impossible for water to exist as a liquid – an essential element for life.

Dr Smith said: ‘We have found that most other planets and solar systems are wildly different from our own.

‘They are very hostile to life as we know it.’

‘The new information we are getting suggests we could effectively be alone in the universe.

‘There are very few solar systems or planets like ours. It means it is highly unlikely there are any planets with intelligent life close enough for us to make contact.’ But his controversial suggestions contradict other leading scientists – who have claimed aliens almost certainly exist.

These arguments are actually quite useful, and I include them in my standard list of scientific arguments for theism. (See below) You have to know this stuff cold. Most people believe in aliens because they watched movies made by artists. As a result, they think that humans are nothing special and that God is not interested in us in particular. Which is very convenient for them, because it means they can do whatever they want and not care what God thinks about what they are doing. If you want to defend against the idea that humans are nothing special, and that we were not placed here for a purpose, and that we are not accountable and obligated to seek and know the Creator/Designer, then you’ll need more than feelings. You’ll need science. You’ll need the best science available.

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News

Why does the news media exaggerate some scientific discoveries?

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What does it take for a planet to be habitable by complex life?

Excerpt:

Complex life in particular probably needs many of the things that we Earthlings enjoy: a rocky terrestrial planet similar in size and composition to the Earth, with plate tectonics to recycle nutrients, and the right kind of atmosphere; a large, well placed moon to contribute to tides and stabilize the tilt of the planet’s axis. That planet needs to be just the right distance from the right kind of single star, in a nearly circular orbit–to maintain liquid water on its surface.

It also needs a home within a stable planetary system that includes some outlying giant planets to protect the inner system from too many deadly comet impacts. That planetary system must be nestled in a safe neighborhood in the right kind of galaxy, with enough heavy elements to build terrestrial planets. And that planet will need to form during the narrow habitable window of cosmic history. (This is to say nothing of having a universe with a fine-tuned set of physical laws to make stars, planets, and people possible in the first place. But that’s another long and complicated story.)

That’s a tall order and it’s not even an exhaustive list of all the requirements.

Now keeping that list in mind, Christian apologist Peter Williams explains how the latest discovery of an exoplanet that might support life was presented to the media by the excited scientists.

Excerpt:

Nasa scientist and Nobel laureate in physics John Mather’s recent comment about ‘Earth-like’ planets was rather timely. Mather said: ‘We know there are earth-like planets out there, but what we don’t know is whether any of them are capable of supporting life.’ Well, Nasa have announced that: “If confirmed, [Gliese 581g] would be the most Earth-like exoplanet yet discovered and the first strong case for a potentially habitable one.”

Thus far we have an unconfirmed report that Gliese 581g might be rocky (since it may be too small to be a gas giant – although the mass given is a minimum figure) and that it seems to be in the right ‘goldilocks’ temperature zone for liquid water – that’s if there is any water there and if the atmosphere is of the right composition!

Of course, the phrase ‘Earth-like’ is being used with some lattitude here: the gravity on Gliese 581g is higher than on earth (because its about three to four times the size of Earth). Moreover, the planet is ‘tidally locked’, meaning it doesn’t rotate (i.e. no seasons). This probably means that there’s only a narrow ‘twilight zone’ of the planet that’s even potentially habitable; assuming, of course, that the atmosphere (if it even has one) hasn’t frozen out over time to the night side of the planet!

At most (it’s hard to extrapolate here), this discovery may indicate that rocky planets in the habitable zone of stars aren’t all that rare; but consider this interesting passage from The Hiffington Post article on the discovery:

‘Vogt and Butler ran some calculations, with giant fudge factors built in, and figured that as much as one out of five to 10 stars in the universe have planets that are Earth-sized and in the habitable zone. With an estimated 200 billion stars in the Milky Way galaxy, that means maybe 40 billion planets that have the potential for life, Vogt said. However, Ohio State University’s Scott Gaudi cautioned that is too speculative about how common these planets are.’

There’s more to habitability – let alone the origin of life – than a chunk of rock at the right temperature!

This is Peter Pan science. They believe what they want to believe.

Many people want to believe that we are nothing special simplifying the world so that they don’t have to worry that maybe, somehow, they were created for a relationship with a cosmic Creator and Designer. Because if that were true,then they might not be free to just do whatever they want without any moral rules in order to make themselves happy. What they really want is to have all the benefits of being created by a loving God, without any of the responsibilities. They like sex, but they don’t like being told how to use it. So they jump at any news story that breaks down the evidence for a Creator/Designer. And they praise moral evil to the skies in order while bashing moral good down, in order to obliterate any vestiges of the idea that there might be any way that they ought to act. They don’t want to be accountable to God. They don’t want moral obligations.

Now look at the latest news from the New Scientist.

Excerpt:

Last month, a team of astronomers announced the discovery of the first alien world that could host life on its surface. Now a second team can find no evidence of the planet, casting doubt on its existence.

The planet, dubbed Gliese 581 g, was found to orbit a dim, red dwarf star every 37 days, according to an analysis by Steven Vogt of the University of California, Santa Cruz, Paul Butler of the Carnegie Institution of Washington in DC, and their colleagues.

Unlike the four previously known planets in the same system and hundreds of others found throughout the Milky Way galaxy, Gliese 581 g sits in the middle of its host star’s habitable zone, where temperatures are in the right range for liquid water to exist. It is also puny enough – weighing about three Earths – to have what is likely a rocky, solid surface.

But it might be too early to claim a definitive detection. A second team of astronomers have looked for signals of Gliese 581 g in their own data and failed to find it.

“We easily recover the four previously announced planets, “b”, “c”, “d”, and “e”. However, we do not see any evidence for a fifth planet in an orbit of 37 days,” says Francesco Pepe of the Geneva Observatory in Switzerland. He presented the results on Monday at an International Astronomical Union symposium in Turin, Italy.

They wanted to believe we were cosmic accidents. Did they distort their data to prove what they wanted to believe? Like hiding the decline to “prove” that capitalism is evil?

We have to be careful about what some educated academic people want. Some educated academic people are sufficiently wealthy and powerful that they can avoid being hurt by most other people. So what they want is to pursue pleasure without being limited by moral rules. So they want to break them down because they view them as “speed bumps” on the road to pleasure in this life. Whatever they say has to be interpreted in light of this desire to get free from moral obligations and moral judgments by you and by your children. They want to normalize the idea that selfishness that causes damage to others is morally neutral. The breakdown of moral realism is what is behind many fads like Dan Brown, sex education, moral relativism, etc.

My previous article on what it takes to make a planet that is habitable by complex life.

Polemics

Is carbon required for complex life? Is the production of carbon fine-tuned?

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Here’s an article by Fuz Rana at Reasons to Believe, talking about alternatives to carbon-based life. (H/T Tough Questions Answered)

Excerpt:

Life as we know it on Earth consists of carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur (CHONPS). But could other elements constitute life as we don’t know it?

Not merely a discussion topic for science-fiction buffs, this question bears on origin-of-life discussions and on the search for extraterrestrial life. Carbon-based life requires a strict set of conditions. But perhaps life based on an element like silicon can exist under more extreme conditions. Few places in our solar system, and presumably beyond, can conceivably support carbon-based life. But for life built upon silicon, habitable sites may well abound throughout the universe.

However, of the 112 known chemical elements, only carbon possesses sufficiently complex chemical behavior to sustain living systems.  Carbon readily assembles into stable molecules comprised of individual and fused rings and linear and branched chains. It forms single, double, and triple bonds. Carbon also strongly bonds with itself as well as with oxygen, nitrogen, sulfur, and hydrogen.

Carbon serves as the hub of complex molecules. You can join lots of different things to it so that they stay put. But the bonds are not so strong that you can’t break things apart if you really want to. That’s what makes it suitable for making complex life, and why people talk about “carbon-based life”.

The rest of the article explains why other kinds of elements like silicon and phosphorus are not suitable for creating life.

Is carbon synthesis fine-tuned?

Here’s an article by agnostic physicist Paul Davies explaining why people think that the production of carbon in the universe is an example of fine-tuning.

Excerpt:

One of the best-known examples of this life-friendly ‘fine-tuning’ of the laws of physics concerns carbon, the element on which all known life is based. The Big Bang that kicked off the universe coughed out plenty of hydrogen and helium, but no carbon. So where did the carbon in our bodies come from? The answer was worked out in the 1950s: most of the chemical elements heavier than helium were manufactured in the cores of stars, as the product of nuclear fusion reactions. It is the energy released by these reactions that makes the Sun and stars shine.

However, while the details of stellar nuclear reactions are fairly straightforward, there is a notable exception: carbon. Most nuclear reactions in stars occur when two atomic nuclei, rushing around at tremendous speed care of the searing temperatures, collide and fuse, forming a heavier element. But carbon cannot be made this way because all the intermediate steps from helium to carbon involve highly unstable nuclei. The solution, spotted by University of Cambridge astronomer Fred Hoyle, is for carbon to form from the simultaneous collision of three helium nuclei.

THERE IS, HOWEVER, a snag. The chances that three helium nuclei will come together at the same moment are tiny. So Hoyle reasoned that a special factor must be at work to boost the rare reaction and lead to our abundance of carbon. If not, then life in general, and Fred Hoyle in particular, would not exist!

Hoyle knew that nuclear reactions can sometimes be greatly amplified by the phenomenon of resonance, similar to the way that an opera singer can shatter a glass by hitting a certain pitch. Carbon nuclei can resonate too, if the masses and energies of the colliding particles that go to form it are just right. Hoyle worked backwards — he knew the particle masses and energies, and he used them to predict the existence of a carbon resonance.

He then pestered Willy Fowler, a nuclear physicist at the California Institute of Technology, to do an experiment to test the prediction. And sure enough, Hoyle was right. Carbon has a resonant state at exactly the right energy to enable stars to manufacture abundant carbon, and thereby seed the universe with this life-encouraging substance.

Hoyle immediately realised just what a close-run thing this mechanism is. Like Baby Bear’s porridge in the story of Goldilocks, the energy of the carbon resonance has to be “just right”. Too high or too low, and the consequences for life would be catastrophic.

So what determines the carbon resonance? Ultimately it depends on the strength of the force that binds protons and neutrons together in the nucleus. That force is one of the unexplained parameters of basic physics — one of the knobs on the Designer Machine if you like. If the strength of the force that determined the carbon resonance was only a fraction stronger or weaker, it is doubtful there would be observers in the universe to worry about the distinct absence of carbon.

Hoyle himself was deeply impressed by this discovery. “It looks like a put-up job,” he quipped. “A commonsense interpretation of the facts suggests that a superintellect has monkeyed with physics,” he later wrote. A similar conclusion was reached by the Princeton physicist Freeman Dyson: “In some sense, the universe knew we were coming.”

He doesn’t accept that God is the fine-tuner though, so the article just concludes with “it could be” speculations, which is all that naturalists can offer against the standard theistic arguments. Still, what he said about the finely-tuned synthesis of carbon is accurate.