Tag Archives: Fine Tuning

William Lane Craig debates Peter Atkins: Does God Exist?

Apologetics 315 posted the video of a debate from the Reasonable Faith speaking tour in the UK:

This is a must-see debate. It was extremely fun to watch.


On Wednesday 26th October 2011 William Lane Craig debated Peter Atkins on the topic: Does God Exist? This debate took place at the University of Manchester  as part of the UK Reasonable Faith Tour with William Lane Craig. The debate was chaired by Christopher Whitehead, Head of Chemistry School at the University. Post-debate discussion was moderated by Peter S Williams, Philosopher in Residence at the Damaris Trust, UK.

Dr. William Lane Craig:

William Lane Craig (born August 23, 1949) is an American analytic philosopher, philosophical theologian, and Christian apologist. He is known for his work on the philosophy of time and the philosophy of religion, specifically the existence of God and the defense of Christian theism. He has authored or edited over 30 books including The Kalam Cosmological Argument (1979), Theism, Atheism and Big Bang Cosmology(co-authored with Quentin Smith, 1993), Time and Eternity: Exploring God’s Relationship to Time (2001), and Einstein, Relativity and Absolute Simultaneity (co-edited with Quentin Smith, 2007).

Craig received a Bachelor of Arts degree in communications from Wheaton College, Illinois, in 1971 and two summa cum laudemaster’s degrees from Trinity Evangelical Divinity School in Deerfield, Illinois, in 1975, in philosophy of religion and ecclesiastical history. He earned a Ph.D. in philosophy under John Hick at the University of Birmingham, England in 1977 and a Th.D. underWolfhart Pannenberg at the University of Munich in 1984.

Dr. Peter Atkins:

Peter William Atkins (born 10 August 1940) is a British chemist and former Professor of Chemistry at the University of Oxford and a Fellow of Lincoln College. He is a prolific writer of popular chemistry textbooks, including Physical ChemistryInorganic Chemistry, and Molecular Quantum Mechanics. Atkins is also the author of a number of science books for the general public, including Atkins’ Molecules and Galileo’s Finger: The Ten Great Ideas of Science.

Atkins studied chemistry at the University of Leicester, obtaining a bachelor’s degree in chemistry, and – in 1964 – a PhD for research into electron spin resonance spectroscopy, and other aspects of theoretical chemistry. Atkins then took a postdoctoral position at the UCLA as aHarkness Fellow of the Commonwealth fund. He returned to Oxford in 1965 as fellow and tutor of Lincoln College, and lecturer in physical chemistry (later, professor of physical chemistry).

You can get the audio of the debate here, along with links to their previous debate from 1998. This debate is accessible and understandable to novice-level Christians.

I am happy when debates like this come out. I have friends who are Christians who doubt the importance of apologetics in evangelism, because they don’t think that apologists can prove anything or win arguments. I have friends who are skeptical of using arguments that assume a 14-billion year old universe, because they think that the Big Bang is compatible with atheism (!). I have friends who think that philosophical arguments have no persuasive force. I have friends who think that nothing can be proven from history, beyond a reasonable doubt. I have co-workers who ask me whether anyone wins these debates. I think that this debate answers all of those questions.

This debate clearly shows why Christians should not shy away from studying science, philosophy and history. We will not discover anything that harms Christian theism by thinking logically and by looking at the evidence. To the contrary, it is the atheist who makes war on the progress of science, and who is forced to resist the clear experimental evidence, and to resort to baseless speculations and blind faith. If you want to see a good debate with an intelligent atheist, I recommend watching the debate between William Lane Craig and Peter Millican instead. But if you want to see a really, really overwhelming defeat for atheism, watch this debate. It is very clear at the end of this debate why Richard Dawkins refused to debate William Lane Craig at Oxford.


I only had time to summarize the first two speeches. Keep in mind that Dr. Craig always shines in his rebuttals, and this debate is no different. So you’ll want to watch those rebuttals. Dr. Atkins literally says in this debate in his first rebuttal “There was nothing here originally. There is nothing here now. But it is an interesting form of nothing which seems to be something.” And the audience laughs nervously. This debate is like that. You will see a clear winner and clear loser in this debate. This fight is decided by knockout.

William Lane Craig opening speech:

1. the origin of the universe
2. the moral argument
3. the resurrection of Jesus

Peter Atkins opening speech:

1. Dr. Craig is stupid, lazy and evil:
– Dr. Craig’s arguments are old: from the 11th century! Old arguments can’t be true
– Dr. Craig is just asserting that “God did it” because he is lazy
– Dr. Craig feels pressured to agree with the theistic majority
– Dr. Craig needs a psychological crutch to comfort him
– Dr. Craig is fearful of death
– Dr. Craig is just wishing for an eternal life of bliss
– Dr. Craig is driven by his heart, and not by his head

2. Origin of the universe:
– Maybe the universe is eternal and has no beginning – we don’t know
– Maybe mommy universes can give birth to daughter universes
– It is naive to think that a cause is needed to cause the creation of the universe from nothing
– Science is just about to show how it is possible that something appears out of nothing without cause
– Some scientists have already begun to speculate about about how something can come into being out of nothing
– Maybe nothing is not really nothing, but it is actually something
– It would be admitting defeat to say that God created the universe out of nothing

3. Fine-Tuning:
– It could be the case that the fundamental constants are not variable
– It could be the case that the fine-tuning of the cosmic constants is a happy accident
– It could be the case that there are billions of billions of unobservable universes that are not fine tuned
– It could be the case that the cosmic constants in these billions and billions of unobservable universes are all random so that some are fine-tuned
– Anyone who infers that an intelligence is the best explanation of a finely-tuned set of life-permitting cosmic constants is lazy

4. Purpose:
– Philosophers and theologians are stupid
– I don’t think that there is purpose in the universe
– I think that the universe is more grand if there is no purpose, so there is no purpose

5. Miracles:
– I don’t think that miracles happen
– The resurrection is a fabrication
– It could be the case that Jesus didn’t exist
– It could be the case that Jesus wasn’t really crucified
– It could be the case that Jesus didn’t  really die after being crucified
– It could be the case that the disciples stole his body
– It could be the case that the women went to the wrong hole in the ground
– the gospels are political propaganda written long after the events they are reporting on

6. Theodicy:
– God has no morally sufficient reason for allowing humans to perform actions that result in suffering
– God has no morally sufficient reason for allowing nature to cause suffering

7. Morality:
–  customs and conventions emerges arbitrarily in different times and places based on an awareness of the consequences of actions, as well as various anecdotes and experiences
–  these customs and conventions are decided based on the goal for survival, in much the same way as politeness and manners emerge for decorum and to avoid offense
– it is childish to presume that there is an umpire God who decides moral values and duties

8. Religious believers are stupid, lazy and evil:
– the notion of God has arisen because people are stupid and want to be comforted
– there are no arguments or evidences for belief in God
– people who believe in God do not think, but instead take refuge in incomprehensible nonsense

Luke Barnes reviews Victor Stenger’s critique of cosmic fine-tuning

Apologetics and the progress of science
Apologetics and the progress of science

Victor Stenger is a famous “Internet Infidel” atheist, but what makes him different is that he is has a PhD in physics. He wrote a book published by the atheist publisher Prometheus Press where he explains why he thinks that the universe is not fine-tuned for embodied sentient life.

An Australian physicist named Luke Barnes decided to write a response to his book, and the response is summarized (without the math!) on Uncommon Descent. Barnes has a PhD in Astronomy from Cambridge. He did postdoctoral research in Switzerland at the Institute for Astonomy, and now he is doing more postdoctoral research at the University of Sydney . The response that he wrote does not talk about God, or explanations of why the fine-tuning happened. I have no idea where his convictions are on any of that, because his response just talks about the fine-tuning itself from a scientific point of view.

Here’s how Uncommon Descent explains Barnes’ response.


Professor Victor Stenger is an American particle physicist and a noted atheist, who popularized the phrase, “Science flies you to the moon. Religion flies you into buildings”. Professor Stenger is also the author of several books, including his recent best-seller, The Fallacy of Fine-Tuning: How the Universe is Not Designed for Humanity (Prometheus Books, 2011). Stenger’s latest book has been received with great acclaim by atheists: “Stenger has demolished the fine-tuning proponents,” writes one enthusiastic Amazon reviewer, adding that the book tells us “how science is able to demonstrate the non-existence of god.”

Well, it seems that the great Stenger has finally met his match. Dr. Luke A. Barnes, a post-doctoral researcher at the Institute for Astronomy, ETH Zurich, Switzerland, has written a scathing critique of Stenger’s book. I’ve read refutations in my time, but I have to say, this one is devastating.

In his paper, Dr. Barnes takes care to avoid drawing any metaphysical conclusions from the fact of fine-tuning. He has no religious axe to grind. His main concern is simply to establish that the fine-tuning of the universe is real, contrary to the claims of Professor Stenger, who asserts that all of the alleged examples of fine-tuning in our universe can be explained without the need for a multiverse.

Dr. Barnes’ ARXIV paper, The Fine-Tuning of the Universe for Intelligent Life (Version 1, December 21, 2011), is available online, and I shall be quoting from it below. Since the paper is quite technical at times, I’ve omitted mathematical equations and kept the references to physical parameters to a minimum, since I simply wish to give readers an overview of what Dr. Barnes perceives as the key flaws in Professor Stenger’s book.

First, the abstract:

The fine-tuning of the universe for intelligent life has received a great deal of attention in recent years, both in the philosophical and scientific literature. The claim is that in the space of possible physical laws, parameters and initial conditions, the set that permits the evolution of intelligent life is very small. I present here a review of the scientific literature, outlining cases of fine-tuning in the classic works of Carter, Carr and Rees, and Barrow and Tipler, as well as more recent work. To sharpen the discussion, the role of the antagonist will be played by Victor Stenger’s recent book The Fallacy of Fine-Tuning: Why the Universe is Not Designed for Us. Stenger claims that all known fine-tuning cases can be explained without the need for a multiverse. Many of Stenger’s claims will be found to be highly problematic. We will touch on such issues as the logical necessity of the laws of nature; objectivity, invariance and symmetry; theoretical physics and possible universes; entropy in cosmology; cosmic inflation and initial conditions; galaxy formation; the cosmological constant; stars and their formation; the properties of elementary particles and their effect on chemistry and the macroscopic world; the origin of mass; grand unified theories; and the dimensionality of space and time. I also provide an assessment of the multiverse, noting the significant challenges that it must face. I do not attempt to defend any conclusion based on the fine-tuning of the universe for intelligent life. This paper can be viewed as a critique of Stenger’s book, or read independently.

Here’s a quote that I wanted to put out there from the paper about how widely accepted fine-tuning is among scientists:

There are a great many scientists, of varying religious persuasions, who accept that the universe is fine-tuned for life, e.g. Barrow, Carr, Carter, Davies, Dawkins, Deutsch, Ellis, Greene, Guth, Harrison, Hawking, Linde, Page, Penrose, Polkinghorne, Rees, Sandage, Smolin, Susskind, Tegmark, Tipler, Vilenkin, Weinberg, Wheeler, Wilczek. They differ, of course, on what conclusion we should draw from this fact. Stenger, on the other hand, claims that the universe is not fine-tuned.

That is a very diverse list. I know that Sandage, Ellis, Page, Tipler and Polkinghorne are theists. But I also know that Weinberg, Rees, Hawking, Greene, and Dawkins are atheists. So scientists all across the spectrum of worldview admit that the fine-tuning is real.

Now, let’s look at Barnes’ paper and see why Victor Stenger disagrees with the view of those scientists.

1) Stenger doesn’t show why the entropy at the beginning of the universe isn’t a case of fine-tuning:


We turn now to cosmology. The problem of the apparently low entropy of the universe is one of the oldest problems of cosmology. The fact that the entropy of the universe is not at its theoretical maximum, coupled with the fact that entropy cannot decrease, means that the universe must have started in a very special, low entropy state. (p. 23)

Let’s return to Stenger’s proposed solution… Stenger takes it for granted that the universe is homogeneous and isotropic. We can see this also in his use of the Friedmann equation, which assumes that space-time is homogeneous and isotropic. Not surprisingly, once homogeneity and isotropy have been assumed, Stenger finds that the solution to the entropy problem is remarkably easy.

We conclude that Stenger has not only failed to solve the entropy problem; he has failed to comprehend it. He has presented the problem itself as its solution. Homogeneous, isotropic expansion cannot solve the entropy problem – it is the entropy problem. Stenger’s assertion that “the universe starts out with maximum entropy or complete disorder” is false. A homogeneous, isotropic spacetime is an incredibly low entropy state. Penrose (1989) warned of precisely this brand of failed solution two decades ago… (p. 26)

2) Stenger responds to calculations showing the need for fine-tuning by speculating that future calculations will overturn the ones we have now:

The Cosmological Constant, Lambda

The cosmological constant problem is described in the textbook of Burgess & Moore (2006) as “arguably the most severe theoretical problem in high-energy physics today, as measured by both the difference between observations and theoretical predictions, and by the lack of convincing theoretical ideas which address it”. A well-understood and well-tested theory of fundamental physics (Quantum Field Theory – QFT) predicts contributions to the vacuum energy of the universe that are [approx.] 10^120 times greater than the observed total value. Stenger’s reply is guided by the following principle:

Any calculation that disagrees with the data by 50 or 120 orders of magnitude is simply wrong and should not be taken seriously. We just have to await the correct calculation. [FOFT p. 219]

This seems indistinguishable from reasoning that the calculation must be wrong since otherwise the cosmological constant would have to be fine-tuned. One could not hope for a more perfect example of begging the question. More importantly, there is a misunderstanding in Stenger’s account of the cosmological constant problem. The problem is not that physicists have made an incorrect prediction. We can use the term dark energy for any form of energy that causes the expansion of the universe to accelerate, including a “bare” cosmological constant (see Barnes et al., 2005, for an introduction to dark energy). Cosmological observations constrain the total dark energy. QFT [quantum field theory – VJT] allows us to calculate a number of contributions to the total dark energy from matter fields in the universe. Each of these contributions turns out to be 10^120 times larger than the total. There is no direct theory-vs.-observation contradiction as one is calculating and measuring different things. The fine-tuning problem is that these different independent contributions, including perhaps some that we don’t know about, manage to cancel each other to such an alarming, life-permitting degree. This is not a straightforward case of Popperian falsification. (pp. 34-35)

3) Stenger doesn’t consider the full range of values when deciding if something is fine-tuned or not:

Protons, Neutrons, Electrons

We turn now to the relative masses of the three most important particles in our universe: the proton, neutron and electron, from which atoms are made. Consider first the ratio of the electron to the proton mass, … of which Stenger says: “…we can argue that the electron mass is going to be much smaller than the proton mass in any universe even remotely like ours.” [FOFT p. 164] (p. 50)

The fact that Stenger is comparing the electron mass in our universe with the electron mass in universes “like ours” is all the evidence one needs to conclude that Stenger doesn’t understand fine-tuning. The fact that universes like ours turn out to be rather similar to our universe isn’t particularly enlightening. (p. 50)

Finally, and most importantly, note carefully Stenger’s conclusion. He states that no fine-tuning is needed for the neutron-proton mass difference in our universe to be approximately equal to the up quark-down quark mass difference in our universe. Stenger has compared our universe with our universe and found no evidence of fine-tuning. There is no discussion of the life-permitting range, no discussion of the possible range of [mass(neutron) – mass(proton)] (or its relation to the possible range of [mass(down quark) – mass(up quark)], and thus no relevance to fine-tuning whatsoever. (p. 51)

Those are just a few of the examples in the paper, highlighted in the Uncommon Descent article (emphasis theirs).

Barnes’ paper has now been published in a peer-reviewed journal. The journal is published by Cambridge University.

Four ways the Earth is fine-tuned for life, and one more

Circumstellar Habitable Zone
Circumstellar Habitable Zone

This is a post from J. Warner Wallace, over at Cold Case Christianity.

Let’s see his four ways first, then I’ll add one that I know.

He writes:

  1. The Earth’s Relationship to the Sun Is Favorable to Life
  2. The Earth’s Atmospheric Conditions Are Favorable to Life
  3. The Earth’s Terrestrial Nature Is Favorable to Life
  4. The Earth’s Relationship to the Moon Is Favorable to Life

I’ve blogged about the moon and plate tectonics before, so we won’t pick #3 and #4 to look at. And I blogged about the stellar habitable zone before, so we won’t pick #1, either.

Let’s look at #2:

The Earth’s Atmospheric Conditions Are Favorable to Life:
The surface gravity of Earth is critical to its ability to retain an atmosphere friendly to life. If Earth’s gravity were stronger, our atmosphere would contain too much methane and ammonia. If our planet’s gravity were weaker, Earth wouldn’t be able to retain enough water. As it is, Earth’s atmosphere has a finely calibrated ratio of oxygen to nitrogen—just enough carbon dioxide and adequate water vapor levels to promote advanced life, allow photosynthesis (without an excessive greenhouse effect), and to allow for sufficient rainfall.

Ok, that’s very good.

Now here is one from me… well, it’s from Science Daily, but I found it. Actually, ECM found it. But he told me.


They suggest that the size and location of an asteroid belt, shaped by the evolution of the Sun’s protoplanetary disk and by the gravitational influence of a nearby giant Jupiter-like planet, may determine whether complex life will evolve on an Earth-like planet.

This might sound surprising because asteroids are considered a nuisance due to their potential to impact Earth and trigger mass extinctions. But an emerging view proposes that asteroid collisions with planets may provide a boost to the birth and evolution of complex life.

Asteroids may have delivered water and organic compounds to the early Earth. According to the theory of punctuated equilibrium, occasional asteroid impacts might accelerate the rate of biological evolution by disrupting a planet’s environment to the point where species must try new adaptation strategies.

The astronomers based their conclusion on an analysis of theoretical models and archival observations of extrasolar Jupiter-sized planets and debris disks around young stars. “Our study shows that only a tiny fraction of planetary systems observed to date seem to have giant planets in the right location to produce an asteroid belt of the appropriate size, offering the potential for life on a nearby rocky planet,” said Martin, the study’s lead author. “Our study suggests that our solar system may be rather special.”

So, that’s 5 ways that the Earth and our solar system are fine-tuned to be habitable for complex, embodied minds. Somebody is looking out for you, so be thankful and recognize.

Actually, I was thinking about this today (Wednesday). At lunch, I was thinking about this girl I know who is very disrespectful of me, of what I’ve achieved, and she won’t take my advice in the areas where I am experienced – education, career, saving, investing. I was fretting about it as I was about to start eating my lunch and suddenly it struck me that I don’t give God enough credit for the many blessings I get from him. I don’t mean things that “go my way”, I mean big things like habitability, and so on. So I said a longer grace than normal today at lunch. I wonder if he sent me that rebellious girl so that I would know how he feels when I don’t recognize and respect him, and just complain about the things he doesn’t do for me.

Anyway, I hope this habitability post will give you something to be thankful for. Our God is an awesome God.

Five reasons why the multiverse is not a good explanation for cosmic fine-tuning

Apologetics and the progress of science
Apologetics and the progress of science

This post by J. Warner Wallace appeared at his Cold Case Christianity blog. It features 5 reasons why the multiverse hypothesis is not a good explanation for the astonishing degree of fine-tuning we find in the cosmic constants and quantities in the universe that allow complex, embodied intelligent life of any conceivable kind.

Here is the list:

  1. This Explanation Lacks Evidential Confirmation
  2. This Explanation Requires Fine-Tuning
  3. This Explanation Relies on Speculative Notions of Time
  4. This Explanation Results in Absurdities Common to “Infinites”
  5. This Explanation Acknowledges an “External” Creative Cause

Let’s take a closer look at numbers two and three:

This Explanation Requires Fine-Tuning
If there is a multiverse vacuum capable of such creative activity, it would be reasonable for us to askhow the physics of such an environment could be so fine-tuned to create a life-permitting universe. As Oxford philosopher Richard Swinburne observes, any proposed multiverse mechanism “needs to have a certain form rather than innumerable possible other forms, and probably constants too that need fine-tuning in the narrow sense . . . if that diversity of universes is to result.” Theoretical physicist, Stephen Hawking, when assessing “eternal inflation” models as a source for the multiverse, admits the same problem of fine-tuning: “The problem is, for our theoretical models of inflation to work, the initial state of the universe had to be set up in a very special and highly improbable way. Thus traditional inflation theory resolves one set of issues but creates another—the need for a very special initial state.”

This Explanation Relies on Speculative Notions of Time
Theorists who propose a pre-existing vacuum must account for the nature of time in this setting. All descriptions of this vacuum describe it as temporal (with bubble universes emerging or quantum events occurring over time). But the Standard Cosmological Model indicates time, as we know it,began with our universe. Physicist Alexander Vilenkin describes the dilemma this way: “There is no matter and no space in this very peculiar state. Also, there is no time . . . In the absence of space and matter, time is impossible to define. And yet, the state of ‘nothing’ cannot be identified with absolute nothingness.” Multiverse explanations must provide an account for the temporal nature of the vacuum lying at the core of their theory.

Regarding  Wallace’s first point, here is MIT physicist Alan Lightman talking about the multiverse’s evidential problems in Harper’s Magazine.

He writes:

The… conjecture that there are many other worlds… [T]here is no way they can prove this conjecture. That same uncertainty disturbs many physicists who are adjusting to the idea of the multiverse. Not only must we accept that basic properties of our universe are accidental and uncalculable. In addition, we must believe in the existence of many other universes. But we have no conceivable way of observing these other universes and cannot prove their existence. Thus, to explain what we see in the world and in our mental deductions, we must believe in what we cannot prove.

Sound familiar? Theologians are accustomed to taking some beliefs on faith. Scientists are not. All we can do is hope that the same theories that predict the multiverse also produce many other predictions that we can test here in our own universe. But the other universes themselves will almost certainly remain a conjecture.

It’s not a good explanation of the data, it’s just desperate speculation. Don’t be one of these people that finds a way to believe what you want to believe. Look through the telescope for yourself. Believe what you can see with your own eyes – that’s the right way to get to the truth.

What are Boltzmann brains, and what challenge do they pose to the multiverse hypothesis?

Apologetics and the progress of science
Apologetics and the progress of science

I thought I would turn to the atheist theoretical physicist Sean Carroll, who has previously debated William Lane Craig, to explain to us what a Boltzmann brain is, and what threat it posts to the multiverse hypothesis.

Here is Sean Caroll, quoted by About.com:

Ludwig Boltzmann was one of the founders of the field of thermodynamics in the nineteenth century.

One of the key concepts was the second law of thermodynamics, which says that the entropy of a closed system always increases. Since the universe is a closed system, we would expect the entropy to increase over time. This means that, given enough time, the most likely state of the universe is one where everything is the in thermodynamic equilibrium … but we clearly don’t exist in a universe of this type since, after all, there is order all around us in various forms, not the least of which is the fact that we exist.

With this in mind, we can apply the anthropic principle to inform our reasoning by taking into account that we do, in fact, exist.

Here the logic gets a little confusing, so I’m going to borrow the words from a couple of more detailed looks at the situation. As described by cosmologist Sean Carroll in From Eternity to Here:

Boltzmann invoked the anthropic principle (although he didn’t call it that) to explain why we wouldn’t find ourselves in one of the very common equilibrium phases: In equilibrium, life cannot exist. Clearly, what we want to do is find the most common conditions within such a universe that are hospitable to life. Or, if we want to be more careful, perhaps we should look for conditions that are not only hospitable to life, but hospitable to the particular kind of intelligent and self-aware life that we like to think we are….

We can take this logic to its ultimate conclusion. If what we want is a single planet, we certainly don’t need a hundred billion galaxies with a hundred billion stars each. And if what we want is a single person, we certainly don’t need an entire planet. But if in fact what we want is a single intelligence, able to think about the world, we don’t even need an entire person–we just need his or her brain.

So the reductio ad absurdum of this scenario is that the overwhelming majority of intelligences in this multiverse will be lonely, disembodied brains, who fluctuate gradually out of the surrounding chaos and then gradually dissolve back into it. Such sad creatures have been dubbed “Boltzmann brains” by Andreas Albrecht and Lorenzo Sorbo….

In a 2004 paper, Albrecht and Sorbo discussed “Boltzmann brains” in their essay:

A century ago Boltzmann considered a “cosmology” where the observed universe should be regarded as a rare fluctuation out of some equilibrium state. The prediction of this point of view, quite generically, is that we live in a universe which maximizes the total entropy of the system consistent with existing observations. Other universes simply occur as much more rare fluctuations. This means as much as possible of the system should be found in equilibrium as often as possible.

From this point of view, it is very surprising that we find the universe around us in such a low entropy state. In fact, the logical conclusion of this line of reasoning is utterly solipsistic. The most likely fluctuation consistent with everything you know is simply your brain (complete with “memories” of the Hubble Deep fields, WMAP data, etc) fluctuating briefly out of chaos and then immediately equilibrating back into chaos again. This is sometimes called the “Boltzmann’s Brain” paradox.

[…]Now that you understand Boltzmann brains as a concept, though, you have to proceed a bit to understanding the “Boltzmann brain paradox” that is caused by applying this thinking to this absurd degree. Again, as formulated by Carroll:

Why do we find ourselves in a universe evolving gradually from a state of incredibly low entropy, rather than being isolated creatures that recently fluctuated from the surrounding chaos?

Unfortunately, there is no clear explanation to resolve this … thus why it’s still classified as a paradox.

Naturalists like to propose the multiverse as a way of explaining away the fine-tuning that we see, and explaining why complex, embodied intelligent beings like ourselves exist. But even if the multiverse hypothesis were true, we still would not expect to observe stars, planets, and conscious embodied intelligent beings. It is far more likely on a multiverse scenario that any observers we had would be “Boltzmann” brains in an empty universe. The multiverse hypothesis doesn’t explain the universe we have, which contains “a hundred billion galaxies with a hundred billion stars each” – not to mention our bodies which are composed of heavy elements, all of which require fine-tuning piled on fine-tuning piled on fine-tuning.

William Lane Craig answered a question about Boltzmann brains a while back, so let’s look at his answer since we saw what his debate opponent said above.

He writes:

Incredible as it may sound, today the principal–almost the only–alternative to a Cosmic Designer to explain the incomprehensibly precise fine tuning of nature’s constants and fundamental quantities is the postulate of a World Ensemble of (a preferably infinite number of) randomly ordered universes. By thus multiplying one’s probabilistic resources, one ensures that by chance alone somewhere in this infinite ensemble finely tuned universes like ours will appear.

Now comes the key move: since observers can exist only in worlds fine-tuned for their existence, OF COURSE we observe our world to be fine-tuned! The worlds which aren’t finely tuned have no observers in them and so cannot be observed! Hence, our observing the universe to be fine-tuned for our existence is no surprise: if it weren’t, we wouldn’t be here to be surprised. So this explanation of fine tuning relies on (i) the hypothesis of a World Ensemble and (ii) an observer self-selection effect.

Now apart from objections to (i) of a direct sort, this alternative faces a very formidable objection to (ii), namely, if we were just a random member of a World Ensemble, then we ought to be observing a very different universe. Roger Penrose has calculated that the odds of our solar system’s forming instantaneously through the random collision of particles is incomprehensibly more probable that the universe’s being fine-tuned, as it is. So if we were a random member of a World Ensemble, we should be observing a patch of order no larger than our solar system in a sea of chaos. Worlds like that are simply incomprehensibly more plentiful in the World Ensemble than worlds like ours and so ought to be observed by us if we were but a random member of such an ensemble.

Here’s where the Boltzmann Brains come into the picture. In order to be observable the patch of order needn’t be even as large as the solar system. The most probable observable world would be one in which a single brain fluctuates into existence out of the quantum vacuum and observes its otherwise empty world. The idea isn’t that the brain is the whole universe, but just a patch of order in the midst of disorder. Don’t worry that the brain couldn’t persist long: it just has to exist long enough to have an observation, and the improbability of the quantum fluctuations necessary for it to exist that long will be trivial in comparison to the improbability of fine tuning.

In other words, the observer self-selection effect is explanatorily vacuous. It does not suffice to show that only finely tuned worlds are observable. As Robin Collins has noted, what needs to be explained is not just intelligent life, but embodied, interactive, intelligent agents like ourselves. Appeal to an observer self-selection effect accomplishes nothing because there is no reason whatever to think that most observable worlds are worlds in which that kind of observer exists. Indeed, the opposite appears to be true: most observable worlds will be Boltzmann Brain worlds.

Allen Hainline explained some of the OTHER problems with the multiverse in a post on Cross Examined’s blog. I recommend taking a look at those as well, because I feel funny even talking about Boltzmann brains. I would rather just say that there is no experimental evidence for the multiverse hypothesis, as I blogged before, and leave it at that. But if the person you are talking to fights you on it, you can disprove the multiverse with the Boltzmann brains.