Tag Archives: Faith

News

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

Podcasts

J. Warner Wallace explains how to prepare young Christians for college

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Here’s a podcast from the master of evidence-gathering and case-making himself, J. Warner Wallace. In this episode, he tries to convince Christians to take the questions that young people ask seriously, and explains what is likely to happen to them in college.

The MP3 is here.

Topics:

  • our nation is becoming more and more secular
  • secularism makes it harder for us to defend our faith and values in public and influence the culture
  • why is secularism happening? it’s because young people are walking away from the faith
  • young Christians are leaving the faith in high school and college
  • this is where the real battleground is – and that’s where apologists need to focus
  • we need to be focused especially on junior high school and high school, and to a lesser degree college
  • it’s good that we have lots scholars working physics, philosophy and biology
  • but what we really need is ordinary Christians to get serious about apologetics and work on young people
  • some people believe that there is no great youth exodus problem: are they right to doubt the statistics
  • it’s undeniable that young people are inarticulate about their faith – that much is certain
  • what young people in church actually believe is not Christianity, but moralistic therapeutic deism
  • young people: life is about feeling good, being liked, and nice people of all religions are saved
  • young people think that there is so little substance to Christianity that it can’t even be discussed
  • the focus among young people today is not on true beliefs, but on being kinds to others
  • even in churches, there is higher respect for helping others than on having knowledge and evidence
  • instead of focusing on the worldview that grounds good works, the focus is on good works
  • young people have learned to minimize discussions about specifics of theology
  • teachers and college professors are hostile to public expressions of evangelical Christianity
  • television is also hostile and much less Christian than it used to be
  • even if young people come back to the church, they come back for the wrong reasons
  • the adults come back for tradition and comfort but they don’t really believe Christianity is true
  • they want to pick and choose what they believe based on what they like, like going to a buffet
  • they return to church when they have kids so that their kids will absorb values – but not truth
  • that’s what we have sitting in the pews: people who think Christianity is false, but “useful”
  • and that’s why so many christians are so liberal on social values (abortion, same-sex marriage)
  • they don’t really accept the Bible as authoritative, they pick and choose what they like and don’t like
  • if Christianity is taught as “useful” then they will dump it when they find something more “useful”
  • people who leave the church are exposed to Christianity, but it doesn’t stick
  • young people lose their faith before college, and then when they escape the nest, they act it out
  • the disconnecting from the faith occurs in high school, but it only becomes public after they leave home
  • young people are becoming more focused on redefining “the good life” with consumption and materialism
  • the typical experience of young adults involves alcohol use, drug use, and recreational sex
  • young people actually want more than niceness – they want real answers to serious questions
  • young people have doubts and questions, but no one in the church or home is equipped to answer them
  • adults have to be involved in the education of young people
  • parents who are engaged in teaching their children Christian truths see much better retention rates
  • we need to stop teaching people (one-way preaching) and start training them (two-way interactive)
  • when you give a young person a definite goal – a fight with a date certain – then they will be engaged
  • when people know that they will fail unless they can perform, then they will be more engaged in learning
  • church needs to be in the business of scheduling battles, and then training young people for the battles
  • there is no sense of urgency, risk and purpose in young people, so the teaching is not effective

I’m sure that you’ll enjoy this very practical podcast.