Tag Archives: Water

News

New study: Saturn’s orbit keeps Earth in the circumstellar habitable zone

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Circumstellar Habitable Zone
Circumstellar Habitable Zone

What do you need in order to have a planet that supports complex life? First, you need liquid water at the surface of the planet. But there is only a narrow range of temperatures that can support liquid water. It turns out that the size of the star that your planet orbits around has a lot to do with whether you get liquid water or not.

A heavy, metal-rich star allows you to have a habitable planet far enough from the star so  the planet can support liquid water on the planet’s surface while still being able to spin on its axis. The zone where a planet can have liquid water at the surface is called the circumstellar habitable zone (CHZ). A metal-rich star like our Sun is very massive, which moves the habitable zone out further away from the star.

If our star were smaller, we would have to orbit much closer to the star in order to have liquid water at the surface. Unfortunately, if you go too close to the star, then your planet becomes tidally locked, like the moon is tidally locked to Earth. Tidally locked planets are inhospitable to life. So we need a star massive enough to give us a nice wide habitable zone far away from the Sun itself.

But even with the right size star, which we have in our solar sytem, we still have CHZ problems. Just because a planet starts off in the circumstellar habitable zone, it doesn’t mean that it will stay there.

Jay Richards tweeted about this new article from the New Scientist, which talks about that very problem.

Excerpt: (links removed)

Earth’s comfortable temperatures may be thanks to Saturn’s good behaviour. If the ringed giant’s orbit had been slightly different, Earth’s orbit could have been wildly elongated, like that of a long-period comet.

Our solar system is a tidy sort of place: planetary orbits here tend to be circular and lie in the same plane, unlike the highly eccentric orbits of many exoplanets. Elke Pilat-Lohinger of the University of Vienna, Austria, was interested in the idea that the combined influence of Jupiter and Saturn – the solar system’s heavyweights – could have shaped other planets’ orbits. She used computer models to study how changing the orbits of these two giant planets might affect the Earth.

Earth’s orbit is so nearly circular that its distance from the sun only varies between 147 and 152 million kilometres, or around 2 per cent about the average. Moving Saturn’s orbit just 10 percent closer in would disrupt that by creating a resonance – essentially a periodic tug – that would stretch out the Earth’s orbit by tens of millions of kilometres. That would result in the Earth spending part of each year outside the habitable zone, the ring around the sun where temperatures are right for liquid water.

Tilting Saturn’s orbit would also stretch out Earth’s orbit. According to a simple model that did not include other inner planets, the greater the tilt, the more the elongation increased. Adding Venus and Mars to the model stabilised the orbits of all three planets, but the elongation nonetheless rose as Saturn’s orbit got more tilted. Pilat-Lohinger says a 20-degree tilt would bring the innermost part of Earth’s orbit closer to the sun than Venus.

So the evidence for a out solar system being fine-tuned for life keeps piling up. It’s just another factor that has to be just right so that complex, embodied life could exist here. All of these factors need to be just right, not just the orbits of any other massive planets. And you need at least one massive planet to attract comets and other such unwelcome intruders away from the life-permitting planets.

Here’s a good clip explaining the circumstellar habitable zone:

The factor I blogged about today is just one of the things you need in order to get a planet that supports life.

Here are a few of the more well-known ones:

  • 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

Here is a study that I wrote about recently about galactic habitable zones.

Polemics

How likely is it for blind forces to sequence a functional protein by chance?

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How likely is it that you could swish together amino acids randomly and come up with a sequence that would fold up into a functional protein?

Evolution News reports on research performed by Doug Axe at Cambridge University, and published in the peer-reviewed Journal of Molecular Biology.

Excerpt:

Doug Axe’s research likewise studies genes that it turns out show great evidence of design. Axe studied the sensitivities of protein function to mutations. In these “mutational sensitivity” tests, Dr. Axe mutated certain amino acids in various proteins, or studied the differences between similar proteins, to see how mutations or changes affected their ability to function properly.10 He found that protein function was highly sensitive to mutation, and that proteins are not very tolerant to changes in their amino acid sequences. In other words, when you mutate, tweak, or change these proteins slightly, they stopped working. In one of his papers, he thus concludes that “functional folds require highly extraordinary sequences,” and that functional protein folds “may be as low as 1 in 10^77.”11 The extreme unlikelihood of finding functional proteins has important implications for intelligent design.

Just so you know, those footnotes say this:

[10.] Douglas D. Axe, “Estimating the Prevalence of Protein Sequences Adopting Functional Enzyme Folds,” Journal of Molecular Biology, 1-21 (2004); Douglas D. Axe, “Extreme Functional Sensitivity to Conservative Amino Acid Changes on Enzyme Exteriors,” Journal of Molecular Biology, Vol. 301:585-595 (2000).

[11.] Douglas D. Axe, “Estimating the Prevalence of Protein Sequences Adopting Functional Enzyme Folds,” Journal of Molecular Biology, 1-21 (2004).

And remember, you need a lot more than just 1 protein in order to create even the simplest living system. Can you generate that many proteins in the short time between when the Earth cools and the first living cells appear? Even if we spot the naturalist a prebiotic soup as big as the universe, and try to make sequences as fast as possible, it’s unlikely to generate even one protein in the time before first life appears.

Here’s Doug Axe to explain his research:

If you are building a protein for the FIRST TIME, you have to get it right all at once – not by building up to it gradually using supposed Darwinian mechanisms. That’s because there is no replication before you have the first replicator. The first replicator cannot rely on explanations that require replication to already be in place.

News

Study: the early Earth’s atmosphere contained oxygen

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Here’s a paper published in the prestigious peer-reviewed science journal Nature, entitled “The oxidation state of Hadean magmas and implications for early Earth’s atmosphere”. This paper is significant because it undermines naturalistic scenarios for the origin of life.

Evolution News explains what the paper is about.

Excerpt:

A recent Nature publication reports a new technique for measuring the oxygen levels in Earth’s atmosphere some 4.4 billion years ago. The authors found that by studying cerium oxidation states in zircon, a compound formed from volcanic magma, they could ascertain the oxidation levels in the early earth. Their findings suggest that the early Earth’s oxygen levels were very close to current levels.

[…]Miller and Urey conducted experiments to show that under certain atmospheric conditions and with the right kind of electrical charge, several amino acids could form from inorganic compounds such as methane, ammonia, and water. Several experiments have been done using various inorganic starting materials, all yielding a few amino acids; however, one key aspect of all of these experiments was the lack of oxygen.

If the atmosphere has oxygen (or other oxidants) in it, then it is an oxidizing atmosphere. If the atmosphere lacks oxygen, then it is either inert or a reducing atmosphere. Think of a metal that has been left outside, maybe a piece of iron. That metal will eventually rust. Rusting is the result of the metal being oxidized. With organic reactions, such as the ones that produce amino acids, it is very important that no oxygen be present, or it will quench the reaction. Scientists, therefore, concluded that the early Earth must have been a reducing environment when life first formed (or the building blocks of life first formed) because that was the best environment for producing amino acids. The atmosphere eventually accumulated oxygen, but life did not form in an oxidative environment.

The problem with this hypothesis is that it is based on the assumption that organic life must have formed from inorganic materials. That is why the early Earth must have been a reducing atmosphere. Research has been accumulating for more than thirty years, however, suggesting that the early Earth likely did have oxygen present.

[…]Their findings not only showed that oxygen was present in the early Earth atmosphere, something that has been shown in other studies, but that oxygen was present as early as 4.4 billion years ago. This takes the window of time available for life to have begun, by an origin-of-life scenario like the RNA-first world, and reduces it to an incredibly short amount of time. Several factors need to coincide in order for nucleotides or amino acids to form from purely naturalistic circumstances (chance and chemistry). The specific conditions required already made purely naturalist origin-of-life scenarios highly unlikely. Drastically reducing the amount of time available, adding that to the other conditions needing to be fulfilled, makes the RNA world hypothesis or a Miller-Urey-like synthesis of amino acids simply impossible.

So here’s where we stand. If you are a materialist, then you need a reducing environment on the early Earth in order to get organic building blocks (amino acids) from inorganic materials. However, the production of these organic building blocks (amino acids) requires that the early Earth atmosphere be oxygen-free. And the problem with this new research, which confirms previous research, is that the early Earth contained huge amounts of oxygen – the same amount of oxygen as we have today. This is lethal to naturalistic scenarios for creating the building blocks of life on the Earth’s surface.

Other problems

If you would like to read a helpful overview of the problems with a naturalistic scenario for the origin of life, check out this article by Casey Luskin.

Excerpt:

The “origin of life” (OOL) is best described as the chemical and physical processes that brought into existence the first self-replicating molecule. It differs from the “evolution of life” because Darwinian evolution employs mutation and natural selection to change organisms, which requires reproduction. Since there was no reproduction before the first life, no “mutation – selection” mechanism was operating to build complexity. Hence, OOL theories cannot rely upon natural selection to increase complexity and must create the first life using only the laws of chemistry and physics.

There are so many problems with purely natural explanations for the chemical origin of life on earth that many scientists have already abandoned all hopes that life had a natural origin on earth. Skeptical scientists include Francis Crick (solved the 3-dimensional structure of DNA) and Fred Hoyle (famous British cosmologist and mathematician), who, in an attempt to retain their atheistic worldviews, then propose outrageously untestable cosmological models or easily falsifiable extra-terrestrial-origin-of-life / panspermia scenarios which still do not account for the natural origin of life. So drastic is the evidence that Scientific American editor John Horgan wrote, “[i]f I were a creationist, I would cease attacking the theory of evolution … and focus instead on the origin of life. This is by far the weakest strut of the chassis of modern biology.”3

The article goes over the standard problems with naturalistic scenarios of the origin of life: wrong atmosphere, harmful UV radiation, interfering cross-reactions, oxygen levels, meteorite impacts, chirality, etc.

Most people who are talking about intelligent design at the origin of life talk about the information problem – how do you get the amino acids to form proteins and how do you get nucleotide bases to code for amino acids? But the starting point for solving the sequencing problem is the construction of the amino acids – there has to be a plausible naturalistic scenario to form them.