Tag Archives: Apologetics

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.

Polemics

Sean Carroll debates William Lane Craig on cosmology and God’s existence

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Carroll was as good of a speaker as Craig in terms of style. Very easy to listen to, very quick on his feet, very civil. There was no clear winner on style.

It was difficult to assess the truth value of scientific points being made, especially for the layperson. I explained a few of them in my posts earlier this week, but I think laypeople might struggle with them if they are hearing about these things for the first time.

A couple of Craig’s slides: (click for larger images)

Slide 1 of 2:

Dr. Craig slide #1 of 2
Dr. Craig slide #1 of 2

Slide 2 of 2:

Dr. Craig slide #2 of 2
Dr. Craig slide #2 of 2

Quick summary: (this is not complete, because I couldn’t get everything they were saying noted)

Dr. Craig defended two arguments: 1) the kalam cosmological argument and the fine-tuning argument.

Dr. Craig supported the origin of the universe with 1) the expansion of the universe and 2) the second law of thermodynamics.

Dr. Craig said that the BGV theorem supports a beginning for the universe.

Dr. Craig said that the consensus of scientists did not accept Carroll’s naturalistic cosmology, quoting Stephen Hawking in support.

Dr. Craig said that multiverse models fall victim to the Boltzmann brain problem, where we should observe Boltzmann brains coming into existence and then phasing out again far more probably than embodied minds. But we observe embodied minds, and no Boltzmann brains.

Dr. Carroll said that science cannot study metaphysical questions.

Dr. Carroll said that science is about making models that may or may not be consistent with the experimental data.

Dr. Carroll said that the BGV theorem does not support a beginning for the universe.

Dr. Carroll proposed 17 alternative cosmologies, but did not provide a shred of scientific evidence for any of them, the way that Craig did for the standard model.

Dr. Carroll refuted Dr. Craig’s citation of Stephen Hawking, and Craig yielded the point.

Dr. Carroll speculated that science might progress to the point where the fine-tuning can be explained without an intelligent cause, and he gave an example of where that happened (inflation).

Dr. Craig argued that all 17 of the models suggested by Carroll either conflicted with evidence, had serious problems or did require a beginning.

Dr. Craig argued that Carroll’s own model required a beginning.

Dr. Craig argued that Carroll’s own model fell victim to the Boltzmann brain problem.

Dr. Craig argued that Carroll’s own model violated the second law of thermodynamics.

Dr. Craig re-stated his point that the baby universe spawning in Carroll’s model was speculative and incomplete, and cited Christopher Weaver’s work.

Dr. Carroll denied that things that pop into being out of nothing require a transcendent cause.

Dr. Carroll reiterated that science can only make naturalistic models, and that he did not have to answer questions about ultimate causes.

Dr. Carroll showed a photo of Alan Guth expressing his opinion that the universe is “probably” eternal. No evidence was given for this assertion.

Dr. Carroll said that the fine-tuning was not done in an optimal way, because one fine-tuned value was lower than it needed to be, and it should be exactly what it needed to be if God did it.

Dr. Carroll said that a finely-tuned universe is more probably in naturalism than in theism, because God can do anything he wants and doesn’t need a fine-tuned universe.

Dr. Carroll said he would stop defending his model now, and would instead defend Aguirre-Gratton.

Dr. Craig gave three reasons why the universe popping into being out of nothing requires a transcendent cause.

First, he said that nothing cannot cause anything to happen, because nothing is nothing.

Second, he said that if things pop into being out of nothing, then why don’t we see it happening all the time with other things.

Third, he said that we have no reason to dismiss the causal principle, especially when it is the basis of scientific inquiry and has been so fruitful in the progress of science.

Dr. Craig reiterated that baby universes in Carroll’s model would be dominated by Boltzmann brains, and we don’t observe that.

Dr. Craig said that even on the quantum gravity models that Carroll mentioned, there would still be a beginning.

Dr. Carroll said that Craig mustn’t say “popped into being” but instead that “there was a first moment of time”.

Dr. Carroll said that his model does indeed violate the second law of thermodynamics “YES!”.

At this point Carroll stopped talking about the topic of the debate and started expressing personal opinions about religion. It’s funny how often atheists do this in debates.

Dr. Carroll said that most theists don’t believe in God because of cosmology, but because of community and feelings.

Dr. Carroll said that science had learned a lot in the last 2000 years, so theism was false.

Dr. Carroll said that most philosophers don’t think that God exists, so theism was false.

Dr. Carroll said microscopes and telescopes were absent 2000 years ago, so theism was false.

Dr. Carroll said that religion should be about community and feelings, not about what is true.

Conclusion:

My conclusion was that Carroll lost because he is just satisfied to throw theories out and not to argue that they are true by citing evidence. Carroll never seemed to be interested in finding out what is true, but instead he just wanted to tell a story that didn’t include God, and assert that by Occam’s Razor, his story was a better explanation. I am not impressed with theoretical speculations, although the layperson might be. I kept waiting for him to respond to Craig’s points about how his model was falsified by experimental evidence and observations, e.g. – the Boltzmann brains or the baby universe generation, and he never cited the evidence I wanted him to cite. Craig did have some evidence for his views, but he could have been stronger in making his case. He could have shown the e-mail from Vilenkin that stated that he had understood the BGV theorem, and was using it correctly, for example.

For me the winning side comes down to evidence. The standard model is the standard model because of scientific evidence. Until that evidence is overturned, then speculative models are of no interest to anyone who is evidence-driven. Speculations are not science. A philosophical presupposition of metaphysical naturalism is not science.

The nice thing is that Robin Collins, one of Craig’s respondents, went deep into the science of the fine-tuning, especially on one of my favorite data points, the cosmic microwave background radiation. The paper he presented is now posted on his web site (H/T Christian Apologetics Alliance). I posted about the CMBR before in my post about particle physicist Michael Strauss lecture on cosmology and fine-tuning at Stanford University and the his more recent lecture at the University of Texas. Note that Strauss is an experimental physicist, not a theoretical physicist like Carroll.

Here’s another review of the debate by Randy Everist of Possible Worlds blog. He explains the back-and-forth over Boltzmann brains and the BGV theorem in more detail.

Commentary

When dealing with a non-Christian, make evidence – not behavior – the main issue

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Pastor Matt posted about something that I think all Christian apologists believe, deep down. (H/T The Poached Egg)

He writes:

Typically, the church has defined loving one’s neighbor as in line with Jesus’ parable of the Good Samaritan (Luke 10:25-37) and Christ’s teaching in passages such as Matthew 25:31-46, in which we are commanded to love the imprisoned, the homeless, the hungry, etc. as if they were Jesus himself. Of course all believers should do so whether by volunteering at a soup kitchen or donating money to ministries like World Help.

But there is more to loving one’s neighbor these days than caring for the poor, as important as that is.  Those of us who live in a first world western country now dwell in a post-Christian society.  Our neighbors are inundated with naturalism masquerading as good science and sound philosophy.  Non-Christians believe the faith is intellectually vacuous.

It shocks many people when those trained in apologetics point out that atheists cannot answer questions like, “How did the universe come into existence?” “Why is our planet so finely tuned for life despite all the odds against it?” “How did life begin?” “Why do humans have consciousness?” “How is there truth or right and wrong without God?” “Why did the disciples die horrible deaths as impoverished traveling peasants rather than deny the resurrection of Jesus?”, etc.

If we are to help bring our neighbors to saving faith, we must first destroy their false ideas of what Christianity is and is not.  That means we must preach the Gospel (2 Cor. 5:21), knock down specious views of the faith and present the truth of what we believe.

Apologetics is not just an intellectual exercise for nerds like me or a debate to be won on college campuses but an increasing tool in loving our neighbors.  For if they do not understand the faith, they will likely not come to faith and that is what the God we love wants and how we must show love to our neighbors.  So, let’s study not just to win arguments but to love others.

That reminds me of 2 Corinthians 10:3-5. Our job is to beat up on false ideas and speculations.

Pastor Matt’s point is critical, I think. Just stop and think for a minute about your non-believing co-workers. Do they know that the universe began to exist? Do they know that the initial conditions and the cosmological constants have to be finely tuned to support things like galaxies, stars, planets and elements heavier than hydrogen? Do they know how much information is in a protein, and how many proteins would be needed to make the first living cell? Do they know what it takes to make a planet that can support life? What facts from the gospels and the Pauline letters pass the tests for historicity? What is the best explanation of those minimal facts?

These are the facts that we share when we discuss spiritual things with people. They are not Christian facts, they are public, testable facts. And yet, almost no one in the culture who is not already a believer is curious to find out these things on their own. But without the evidence, how are they supposed to take the first step towards a relationship with God through Jesus Christ? It’s not possible. This is a propositional faith, and we know it’s true by evidence. To share the evidence with someone so they can decide is as loving as sharing the evidence about retirement planning, or the evidence about nutrition, or the evidence about fitness and exercise, or the evidence about career planning. When you love someone, you tell them the facts, and then they decide. Evangelism is the same thing.

Here’s something from a recent post by J. Warner Wallace, where he talks about doing apologetics with people who have not yet decided whether God exists or not.

The Undecided

In many ways, this group holds the most promise. People who are undecided usually fall into two categories. Some have never really given the issue much thought. They’re neither for nor against; they’ve simply been living unaware. You may be the first person to introduce them to the issues you are trying to share. If so, remember the importance of a first impression. What you say or do will have an impact on the work of those who follow you. The second group of “undecideds” are people who have given the issue some thought, but are just beginning to make their decision. For this group of people, your defense of Christianity may very well be the deciding factor. The responsibility you and I have with the undecided is daunting, but it’s a privilege to play a small part in their decision.

OK, so I want to make a point about this. So often, I see Christian parents and leaders trying to focus on changing people’s behaviors, and not by giving them evidence. Instead of trying to convince them about what’s true, they tell them Bible verses, or maybe tell them they are going to Hell. But given what Matt and J. Warner said, I don’t want us to be focused on changing outward behavior. I want us to be focused on showing people what is true and showing our work – how we arrived at these true beliefs. You are doing Christianity wrong if you focus on getting behaviors from people by shaming them, overpowering them or scaring them.

So in my case, I’m not trying to get non-Christians to act like Christians when they have no reasons to be one. I’m trying to get them to settle on true beliefs – so that each of them and God can shake hands and be reconciled, responding to his drawing them of their own free will. Then, they can decide how they are going to act. And how they act might be even better than what we had in mind for them when all we wanted was for them to quit swearing and eat their vegetables. The Christian life is bigger than just making people do what we want them to do.