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How tidal effects improve the habitability of a planet

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Circumstellar Habitable Zone
Circumstellar Habitable Zone

Science Daily reports on a new factor that affects planetary habitability: tides. Specifically, tides can affect the surface temperature of a planet, which has to be within a certain range in order to support liquid water – a requirement for life of any conceivable kind.

Excerpt:

Tides can render the so-called “habitable zone” around low-mass stars uninhabitable. This is the main result of a recently published study by a team of astronomers led by René Heller of the Astrophysical Institute Potsdam.

[…]Until now, the two main drivers thought to determine a planet’s temperature were the distance to the central star and the composition of the planet’s atmosphere. By studying the tides caused by low-mass stars on their potential earth-like companions, Heller and his colleagues have concluded that tidal effects modify the traditional concept of the habitable zone.

Heller deduced this from three different effects. Firstly, tides can cause the axis of a planet`s rotation to become perpendicular to its orbit in just a few million years. In comparison, Earth’s axis of rotation is inclined by 23.5 degrees — an effect which causes our seasons. Owing to this effect, there would be no seasonal variation on such Earth-like planets in the habitable zone of low-mass stars. These planets would have huge temperature differences between their poles, which would be in perpetual deep freeze, and their hot equators which in the long run would evaporate any atmosphere. This temperature difference would cause extreme winds and storms.

The second effect of these tides would be to heat up the exoplanet, similar to the tidal heating of Io, a moon of Jupiter that shows global vulcanism.

Finally, tides can cause the rotational period of the planet (the planet’s “day”) to synchronize with the orbital period (the planet’s “year”). This situation is identical to the Earth-moon setup: the moon only shows Earth one face, the other side being known as “the dark side of the moon.” As a result one half of the exoplanet receives extreme radiation from the star while the other half freezes in eternal darkness.

The habitable zone around low-mass stars is therefore not very comfortable — it may even be uninhabitable.

Here is my previous post on the factors needed for a habitable planet. Now we just have one more. I actually find this article sort of odd, because my understanding of stars was that only high-mass stars could support life at all. This is because if the mass of the planet was too low, the habitable zone wouldbe very close to the star. Being too close to the star causes tidal locking, which means that the planet doesn’t spin on its axis at all, and the same side faces the star. This is a life killer.

This astrophysicist who teaches at the University of Wisconsin explains it better than me.

Excerpt:

Higher-mass stars tend to be larger and luminous than their lower-mass counterparts. Therefore, their habitable zones are situated further out. In addition, however, their HZs are much broader. As an illustration,

  • a 0.2 solar-mass star’s HZ extends from 0.1 to 0.2 AU
  • a 1.0 solar-mass star’s HZ extends from 1 to 2 AU
  • a 40 solar-mass star’s HZ extends from 350 to 600 AU

On these grounds, it would seem that high-mass starts are the best candidates for finding planets within a habitable zone. However, these stars emit most of their radiation in the far ultraviolet (FUV), which can be highly damaging to life, and also contributes to photodissociation and the loss of water. Furthermore, the lifetimes of these stars is so short (around 10 million years) that there is not enough time for life to begin.

Very low mass stars have the longest lifetimes of all, but their HZs are very close in and very narrow. Therefore, the chances of a planet being formed within the HZ are small. Additionally, even if a planet did form within the HZ, it would become tidally locked, so that the same hemisphere always faced the star. Even though liquid water might exist on such a planet, the climactic conditions would probably be too severe to permit life.

In between the high- and low-mass stars lie those like our own Sun, which make up about 15% percent of the stars in the galaxy. These have reasonably-broad HZs, do not suffer from FUV irradiation, and have lifetimes of the order of 10 billion years. Therefore, they are the best candidates for harbouring planets where life might be able to begin.

This guy is just someone I found through a web search. He has a support-the-unions-sticker on his web page, so he’s a liberal crackpot. But he makes my point, anyway, so that’s good enough for me.

Maybe the new discovery is talking about this now, but I already knew about the tides and habitability, because I watched The Privileged Planet DVD. Actually that whole video is online, and the clip that talks about the habitable zone and water is linked in this blog post I wrote before.

Videos

Stephen C. Meyer lectures on intelligent design and the origin of life

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A MUST-SEE lecture based on Dr. Stephen C. Meyer’s book “Signature in the Cell“.

You can get an MP3 of the lecture here. (30 MB)

I highly recommend watching the lecture, and looking at the slides. The quality of the video and the content is first class. There is some Q&A (9 minutes) at the end of the lecture.

Topics:

  • intelligent design is concerned with measuring the information-creating capabilities of natural forces like mutation and selection
  • Darwinists think that random mutations and natural selection can explain the origin and diversification of living systems
  • Darwinian mechanisms are capable of explaining small-scale adaptive changes within types of organisms
  • but there is skepticism, even among naturalists, that Darwinian mechanisms can explain the origin of animal designs
  • even if you concede that Darwinism can account for all of the basic animal body plans, there is still the problem of life’s origin
  • can Darwinian mechanisms explain the origin of the first life? Is there a good naturalistic hypothesis to explain it?
  • there are at least two places in the history of life where new information is needed: origin of life, and Cambrian explosion
  • overview of the structure of DNA and protein synthesis (he has helpful pictures and he uses the snap lock blocks, too)
  • the DNA molecule is composed of a sequence of bases that code for proteins, and the sequence is carefully selected to have biological function
  • meaningful sequences of things like computer code, English sentences, etc. require an adequate cause
  • it is very hard to arrive at a meaningful sequence of a non-trivial length by randomly picking symbols/letters
  • although any random sequence of letters is improbable, the vast majority of sequences are gibberish/non-compiling code
  • similarly, most random sequences of amino acids are lab-proven (Doug Axe’s work) to be non-functional gibberish
  • the research showing this was conducted at Cambridge University and published in the Journal of Molecular Biology
  • so, random mutation cannot explain the origin of the first living cell
  • however, even natural selection coupled with random mutation cannot explain the first living cell
  • there must already be replication in order for mutation and selection to work, so they can’t explain the first replicator
  • but the origin of life is the origin of the first replicator – there is no replication prior to the first replicator
  • the information in the first replicator cannot be explained by law, such as by chemical bonding affinities
  • the amino acids are attached like magnetic letters on a refrigerator
  • the magnetic force sticks the letters ON the fridge, but they don’t determine the specific sequence of the letters
  • if laws did determine the sequence of letters, then the sequences would be repetitive
  • the three materialist explanations – chance alone, chance and law, law alone – are not adequate to explain the effect
  • the best explanation is that an intelligent cause is responsible for the biological explanation in the first replicator
  • we know that intelligent causes can produce functional sequences of information, e.g. – English, Java code
  • the structure and design of DNA matches up nicely with the design patterns used by software engineers (like WK!)

There are some very good tips in this lecture so that you will be able to explain intelligent design to others in simple ways, using everyday household items and children’s toys to symbolize the amino acids, proteins, sugar phosphate backbones, etc.

Proteins are constructed from a sequence of amino acids:

A sequence of amino acids forming a protein
A sequence of amino acids forming a protein

Proteins sticking onto the double helix structure of DNA:

Some proteins sticking onto the sugar phosphate backbone
Some proteins sticking onto the sugar phosphate backbone

I highly, highly recommend this lecture. You will be delighted and you will learn something.

Here is an article that gives a general overview of how intelligent design challenges. If you want to read something more detailed about the material that he is covering in the lecture above related to the origin of life, there is a pretty good article here.

There is a good breakdown of some of the slides with helpful flow charts here on Uncommon Descent.

Positive arguments for Christian theism

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Does reading science fiction predispose people to atheism?

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A conflict of worldviews
A conflict of worldviews

My friend ECM thinks that science fiction that people read when they are younger causes them to believe that the religion is anti-science and that the progress of science always disproves religion. The stories they read colors their views of science and religion for life, before they ever get to assessing evidence. And that’s why when we produce evidence for them in debates, they will believe in speculations rather than go where the evidence leads. So they believe that maybe unobservable aliens caused the origin of life, and that maybe the untestable multiverse theory explains the fine-tuning of cosmological constants, and that maybe this universe has existed eternally despite the well-supported Big Bang theory which shows that the universe began to exist. Maybe, maybe, maybe. They seem to think that untestable speculations are “good enough” to refute observational evidence – and maybe it’s because of all the science fiction that they’ve read.

Here’s an article in the American Spectator that talks a bit about it.

Excerpt:

A magazine I frequently write for (not this one) recently published a review of a book of essays advocating atheism. The reviewer pointed out with some enthusiasm that a large number of the contributors were science-fiction writers.

This left me somewhat nonplussed. I publish a good deal of science fiction myself, I have also read quite a lot of it, and I am quite unable to see why writing it should be held to particularly qualify anyone to answer the question of whether or not there is a God.

[…]Historically the contribution of the Catholic Church to astronomy was massive and unequalled. Without it astronomy might very well never have grown out of astrology at all. Cathedrals in Bologna, Florence, Paris, Rome and elsewhere were designed in the 17th and 18th centuries to function as solar observatories. Kepler was assisted by a number of Jesuit astronomers, including Father Paul Guldin and Father Zucchi, and by Giovanni Cassini, who had studied under Jesuits. Cassini and Jesuit colleagues were eventually able to confirm Kepler’s theory on the Earth having an elliptical orbit. J.L. Heilbron of the University of California has written:

The Roman Catholic Church gave more financial aid and social support to the study of astronomy over six centuries, from the recovery of ancient learning during the late Middle Ages into the Enlightenment, than any other, and, probably, all other, institutions.

Science fiction is, by definition, fiction, that is, it deals with things which are the product of a writer’s imagination and are not literally true. In any event, what is and what is not science fiction is hard to define. Simply to say it is about science is meaningless, and while some science-fiction writers are qualified scientists, many are not. Probably even fewer are trained theologians.

Science fiction makes the mysteries of the universe seem easy to an atheist. Everything can be easily explained with fictional future discoveries. Their speculations about aliens, global warming and eternal universes are believed without evidence because atheists want and need to believe in those speculations. In the world of science fiction, the fictional characters can be “moral” and “intelligent” without having to bring God or the evidence for God into the picture. That’s very attractive to an atheist who wants the feeling of being intelligent and moral without having to weight actual scientific evidence or ground their moral values and behavior rationally. The science fiction myths are what atheists want to believe. It’s a placebo at the worldview level. They don’t want cosmic microwave background radiation – they want warp drives. They don’t want WMAP satellite confirmation of nucleosynthesis – they want holodecks.

Why do people become atheists?

My theory is mainly that atheists adopt atheism because they want pleasure, especially sexual pleasure, without any restraints or guilt. They want to believe that sex without commitment has no consequences, especially a consequence like God judging them for it. Another contributing factor may be that atheists want to be thought of as smart by “the right people” – to sort of blindly accept whatever the “smart people” accept without really searching out reasons or dissenting views. They do this so that they are able to look down at some other group of people so they can feel better about themselves and be part of the right group – without actually having to weigh the evidence on both sides. And lastly, atheism may also be caused by weak fathers or abandoning fathers. But I think that ECM’s science fiction theory has merit, as well. I think that all four of these factors help to explain why atheists believe in a discredited worldview in the teeth of scientific progress.

I wonder if my readers would take some time out to investigate whether their atheist friends have been influenced by reading science fiction and whether they still read it.