Tag Archives: Aliens

Polemics

What makes a planet suitable for supporting complex life?

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The Circumstellar Habitable Zone (CHZ)

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.

Circumstellar Habitable Zone
Circumstellar Habitable Zone

Here, watch a clip from The Privileged Planet: (Clip 4 of 12, full playlist here)

But there’s more.

The Galactic Habitable Zone (GHZ)

So, where do you get the heavy elements you need for your heavy metal-rich star?

You have to get the heavy elements for your star from supernova explosions – explosions that occur when certain types of stars die. That’s where heavy elements come from. But you can’t be TOO CLOSE to the dying stars, because you will get hit by nasty radiation and explosions. So to get the heavy elements from the dying stars, your solar system needs to be in the galactic habitable zone (GHZ) – the zone where you can pickup the heavy elements you need but not get hit by radiation and explosions. The GHZ lies between the spiral arms of a spiral galaxy. Not only do you have to be in between the arms of the spiral galaxy, but you also cannot be too close to the center of the galaxy. The center of the galaxy is too dense and you will get hit with massive radiation that will break down your life chemistry. But you also can’t be too far from the center, because you won’t get enough heavy elements because there are fewer dying stars the further out you go. You need to be in between the spiral arms, a medium distance from the center of the galaxy.

Like this:

Galactic Habitable Zone
Galactic Habitable Zone and Solar Habitable Zone

Here, watch a clip from The Privileged Planet: (Clip 10 of 12, full playlist here)

The GHZ is based on a discovery made by astronomer Guillermo Gonzalez, which made the front cover of Scientific American in 2001. That’s right, the cover of Scientific American. I actually stole the image above of the GHZ and CHZ (aka solar habitable zone) from his Scientific American article (linked above).

These are just a few 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

By the way, you can watch a lecture with Guillermo Gonzalez explaining his ideas further. This lecture was delivered at UC Davis in 2007. That link has a link to the playlist of the lecture, a bio of the speaker, and a summary of all the topics he discussed in the lecture. An excellent place to learn the requirements for a suitable habitat for life.

News

Pew survey: evangelical Christians least likely to believe superstitious nonsense

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The Pew Research survey is here.

They are trying to see which groups believe in superstitions and new age mysticism.

Here are the parts that I found interesting:

Click for full image.

Click for full image.

Notice the numbers for Republicans vs Democrats, conservatives vs. liberals, and church-attending vs non church-attending. The least superstitious people are conservative evangelical Republicans, while the most superstitious people are Democrat liberals who don’t attend church. I think there is something to be learned from that. It’s consistent with the results of a Gallup survey that showed that evangelical Christians are the most rational people on the planet.

Here’s the Wall Street Journal article about the Gallup survey entitled “Look Who’s Irrational Now“.

Excerpt:

The reality is that the New Atheist campaign, by discouraging religion, won’t create a new group of intelligent, skeptical, enlightened beings. Far from it: It might actually encourage new levels of mass superstition. And that’s not a conclusion to take on faith — it’s what the empirical data tell us.

“What Americans Really Believe,” a comprehensive new study released by Baylor University yesterday, shows that traditional Christian religion greatly decreases belief in everything from the efficacy of palm readers to the usefulness of astrology. It also shows that the irreligious and the members of more liberal Protestant denominations, far from being resistant to superstition, tend to be much more likely to believe in the paranormal and in pseudoscience than evangelical Christians.

The Gallup Organization, under contract to Baylor’s Institute for Studies of Religion, asked American adults a series of questions to gauge credulity.

[…]The answers were added up to create an index of belief in occult and the paranormal. While 31% of people who never worship expressed strong belief in these things, only 8% of people who attend a house of worship more than once a week did.

Even among Christians, there were disparities. While 36% of those belonging to the United Church of Christ, Sen. Barack Obama’s former denomination, expressed strong beliefs in the paranormal, only 14% of those belonging to the Assemblies of God, Sarah Palin’s former denomination, did. In fact, the more traditional and evangelical the respondent, the less likely he was to believe in, for instance, the possibility of communicating with people who are dead.

When I think of the “weird” things that evangelical Christians believe, I think of the origin of the universe, the cosmic fine-tuning, the origin of life and the sudden origin of animal body plans in the Cambrian. All of this is superstition to an atheist, and yet all of it is rooted in mainstream science. Not just that, but they’ve grown stronger as science has progressed. I can accept the fact that an atheist may be ignorant of the science that defeats his atheism, but that’s something that has to be remedied with more studying of the evidence, not less. If you generate a worldview by 1) your desire to dispense with moral judgment and/or 2) your desire to prefer Star Trek and Star Wars to mainstream science, then of course you are going to have an irrational worldview. I’m not saying that all atheists do this, surely someone like Peter Millican does not. But for rank-and-file Dawkins acolytes, I think this is pretty accurate, and it’s why we get the survey results that we do.

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.