Luke Barnes and Fine Tuning

KEVIN HARRIS: Bill, a colleague of yours that we’ve talked about a lot was recently interviewed^[1] about the Reasonable Faith animated video on the argument from fine-tuning^[2]. He basically agrees with you but offers some nuances. I thought it was funny. I saw on Facebook a lot of people were talking about this interview and they all said, “Luke Barnes basically agrees with Dr. Craig.” Bottom line. But he is offering a few nuances.

DR. CRAIG: Yes.

KEVIN HARRIS: Talk a little bit about Luke Barnes before we go to this first clip.

DR. CRAIG: I first met Luke Barnes when I was in Australia on that debate tour with Lawrence Krauss which took us to Sydney and Brisbane and Adelaide and Melbourne. While I was in Sydney speaking at the university there this young man approached me and introduced himself and said, “I'm Luke Barnes. I am an astrophysicist here at the University of Sydney, and I'm interested in your work and interested in some of these same questions.” And we became friends and began to then correspond and collaborate over the years. He's been a great help to me in my work on the fine-tuning argument in particular. In the Zangmeister animated video on the fine-tuning of the universe, Luke served as one of our scientific advisors for that video. It was he who checked the accuracy of all of the examples of fine-tuning that we give in the video, and so we owe him a real debt for his fine work.

KEVIN HARRIS: This video is from Jordan Hampton, and his channel is called The Analytic Christian. I want to give Jordan a shout out. In fact, he's been doing a series, Bill, on you bringing in people to interact with your work. Four or five he's done. We'll look at a couple in the next few weeks or so, including the one today. I want to point out that these Reasonable Faith videos are designed to be brief overviews of the topics for the YouTube crowd. They're very good, the Zangmeister videos, but they're not hours-long exhaustive treatments. I mean, that would be a long movie on some of these topics. Luke Barnes acknowledges that in this interview. He said, “Look, this is a five minute video.” But let's go to the first clip as they begin interacting with that Reasonable Faith video. Here it is.

DR. BARNES: Again, there's a couple of things I'd want to nuance a little bit in the physics of it, but mostly it's generally sort of roughly correct. So there are actually about 30 constants of nature in the best theories we have. There's a core of about 10. It's kind of the 10 that they showed there on screen actually rather than all of them. And even within those 10 there are varying degrees of how much you can change it and still have a life-permitting universe. The video then zoomed in on a couple of the interesting ones. The strength of gravity – you’ll remember that with the dial, 1 part in 10 to the 60. That's an odd way to put it but that's sort of broadly correct. Basically the expansion of the universe at a very early stage has to be very close to being what's called critical and so if you're a very small part this way it's expanding too fast and everything gets too far away from everything else and structure doesn't form. The other way the universe doesn't expand fast enough; it recollapses.

KEVIN HARRIS: There's the opening intro there where he begins to talk about those finely tuned constants in the universe.

DR. CRAIG: Yes. And what Luke says there is that the video basically underplays its case. He says the video mentions around 10 of these examples of fine-tuning when in fact there are some 30 constants that require fine-tuning to various degrees that aren't even mentioned. So that actually reinforces, I think, the strength of the video's conclusion. Gravitation that he mentions there is just one of these. If you alter the gravitational force marginally by making it stronger, the whole universe would recollapse into a black hole. If you [weaken]^[3] the force of gravity then the universe will expand so quickly that stars and galaxies would never congeal and there would be no place for life. So the force of gravity in the early universe needs to be right at that critical density level that will allow the universe to expand and not recollapse quickly but long enough to form galaxies and stars where life can evolve and exist.

KEVIN HARRIS: Let's go to clip number two. He continues.

DR. BARNES: Fine-tuning is about life-permitting universes relative to the total. On some level, of course, any universe is going to be unique and weird and rare. The question is not whether our universe is unique and weird and rare; it's whether a life-permitting universe is. So instead of asking what's the bit of the total where our universe is or a universe which has that sort of low entropy – the unlikeliness that we see around us. It's a question of how finely does the Creator have to point . . . how finely does that need to happen – not to hit our universe but to hit a universe which can permit life. And that number is still absurdly small, but 10 to the 10 to the 60 maybe. I've seen some people estimate it to be in that sort of ballpark. Nothing depends on . . . it's not like 10 to the 10 to 123 and the argument's good but 10 to the 10 to the 60 and it's no good. But there's some interesting little details in at least the physics of what's presented there.

KEVIN HARRIS: Yeah, if the numbers are off a little bit – a few billion here or there – it's okay.

DR. CRAIG: I think that the point that he's making is a very good one that I've made in my published work. The fine-tuning argument is not trying to explain why this universe exists, but why a life-permitting universe exists. The analogy I love to give on this is a lottery in which a billion billion billion white ping-pong balls are mixed together and one orange ping-pong ball is thrown into the horde. Then one ball is drawn randomly from the horde. Now, whichever ball is drawn will be equally improbable. Any particular ball is equally improbable. Nevertheless, it is overwhelmingly more probable that whichever ball is drawn it will be white rather than orange. And that's the correct analogy for the probability of a life-permitting universe. We're not interested in why this particular universe was drawn. Rather we're interested in why the universe that was drawn is a life-permitting rather than a life-prohibiting universe.

KEVIN HARRIS: He continues. Here's another excerpt. Let's go to clip number three from Luke Barnes.

DR. BARNES: So three options are necessity, chance, and design. The universe had to be life-permitting or it could have been any old way and we just got lucky or someone ahead of time thought through which of the possibilities they wanted and chose this one because it's got some interesting stuff in it. Let's go through those. Necessity. What I like about the presentation there is that people take it for granted . . . whenever this option's thrown up there I don't think people realize what a very extreme thing to think about the universe – that it must have been life-permitting, that it's impossible for a universe to be not life-permitting. Generations of atheists are trying to tell us that it's just a typical universe, we’re just a third rock around an average star in the outskirts of an average galaxy in a universe where there's all these galaxies. We're not at the center of anything. Life is just the sort of thing that matter does from time to time when it gets together. There's nothing particularly unique or special going on around here. This is a typical universe. How do we weigh up those two options? What fine-tuning suggests is let's go and make some other universes so we at least have an idea of what could have been. A very systematic and useful way to do that is not just to sort of imagine them but let's take the laws of nature as we know them and change these constants a bit as a method of seeing what could have been. This is why I like that the video is sort of presenting (even if it's only in passing) how extreme this option is. You've got to say something like life-permitting universes are inevitable, that a life-prohibiting universe is impossible. You are not just in “this theory explains the data better than that theory.” It's now saying what's possible and what's impossible and all those sorts of things.

KEVIN HARRIS: There's an intro into the three parts – necessity or chance or design – and he talks about necessity. He doesn't see how anybody could even believe that.

DR. CRAIG: This is just a very implausible alternative. What's important to understand is that in these fine-tuning discussions scientists hold constant the laws of nature and then what they alter is not the laws of nature, they alter the values of the constants and quantities that appear in the laws of nature. And those values are independent of the laws of nature. The laws of nature can describe a vast range of universes having different values of the fundamental constants and quantities. So there's simply no ground at all for saying that the values of those constants and quantities are physically necessary. They're not. They're independent of nature's laws. Moreover, it's not just the constants that must be fine-tuned but these arbitrary quantities that are just put in at the beginning as initial conditions. For example, the ratio between matter and antimatter is just an arbitrary initial condition of the universe, and there's nothing in physics about laws of initial conditions that would mandate that these have to be a certain way. So the person who tries to say that the values of the constants and quantities are physically necessary is taking a very radical line for which there is no justification. I think that's why this first possibility is not really taken seriously in cosmological discussions today. It's really the second alternative, the alternative of chance, where the debate lies.

KEVIN HARRIS: We're going to talk about that here in just a moment – Luke Barnes does. In this next clip he mentions the atheist philosopher Graham Oppy. Here's clip number four.

DR. BARNES: There is an approach to defending necessity which I must admit I don't fully understand but it's taken by Graham Oppy who's an Australian philosopher of religion and an atheist. My apologies because I'm probably not going to get this right, but his idea is basically we test . . . we've got this option of saying that something in our worldview is necessary. It just has to be that way, and that's a postulate that we can make. How do we know whether we're right or wrong about that postulate? Well, we can just test it according to what's the best explanation of the world around us. So he would say the idea that the fundamental properties of our universe are necessary (like the mass of the electron) just is the best explanation for why this universe is as it is. It sort of solves the fine-tuning problem by saying sort of by fiat, by announcement, by declaration, that all those other universes that you think are life-prohibiting are actually impossible. Now, he hasn't got any deeper reason for that. As a physicist, what I'd hope for is if you have some reason why the electron mass has to be what it is, what that means is you could sit down with pen and paper and mathematically derive what it is and tell us what it is in terms of some sort of equation. He hasn't got anything like that. He's just got some declaration that this is the best way to explain the universe.

KEVIN HARRIS: I don't know what it is about these Australian guys. They sure are smart. You know, Luke Barnes, Graham Oppy.

DR. CRAIG: Graham Oppy is a compatriot of Luke Barnes. But notice that I said that cosmologists don't think that these values of the constants and quantities are physically necessary. But Graham Oppy, a philosopher, simply asserts that maybe they're metaphysically necessary – that the initial conditions of the universe are just metaphysically necessary and couldn't have been different. As Barnes says, he has no justification for such an assertion. It's just a bare assertion without justification. It seems to me to be enormously implausible. I think we have a very strong intuition of the contingency of the universe – that the universe didn't have to have these initial conditions. Scientists play with toy models of the universe all the time in which they vary the initial conditions or the laws of nature as well as the fundamental constants and quantities. It just seems very intuitive that the universe is metaphysically contingent. But I think the real coup de grace for this argument is that the universe had a beginning. If the universe began to exist then it cannot be metaphysically necessary because a metaphysically necessary being must be an eternal being. It's impossible for it not to exist, and therefore the very beginning of the universe, I think, shows that the universe is radically contingent. The only way I could think of for Oppy to avoid this problem would be to adopt what's called a tenseless theory of time according to which temporal becoming is an illusion of human beings. In fact, the universe did not come into being when it began to exist – the whole four-dimensional space-time continuum just exists tenselessly and metaphysically necessary. And that takes us into a totally different debate over competing theories of time. Many years ago I realized that one's theory of time is vital for the kalam cosmological argument which says that whatever begins to exist has a cause, the universe began to exist, therefore the universe has a cause. Therefore, I devoted about 11 years to the study of the philosophy of time and God's relationship to time. I argue at length both for the tensed theory of time and against the tenseless theory of time. I think we have good reasons for rejecting Oppy’s necessitism with respect to the beginning of the universe.

KEVIN HARRIS: That's necessity. Let's check out what Luke says about the chance alternative. In this first clip he begins to discuss the multiverse. Here it is.

DR. BARNES: Generally it starts off all right. Just saying “we'll just take our chances” – the probabilities here, if they are as fine-tuning thinks they are, they're not probabilities to be messed with. I don't know how much of a convinced atheist you are, you're not that convinced that 10 to the 10 to the 123 or to 60 or 10 to 120 or 10 to the 90 shouldn't start changing your mind about these sorts of things. So that's a good point. Then it raises the multiverse, and there were sort of three points being made there. The first is that there's no evidence for the multiverse. Again I think the reply would be the same maneuver that's made that sort of Oppy tries to make which is to say fine-tuning itself is evidence for the multiverse. If the multiverse is correct then that would explain why our universe exists with the right set of constants for life because there's possibilities all over the place, and why we observe such a universe is because there's no one around observing all the dead universes.

DR. CRAIG: Could we pause at that point?

KEVIN HARRIS: Yeah, go ahead.

DR. CRAIG: Let’s pause at this point and respond to that first argument. The problem with appealing to the fine-tuning as evidence for multiverse is that the fine-tuning is equally evidence for the existence of a designer. And so it's a wash. What the video means when it says there's no evidence for a multiverse, it means there is no independent evidence. Whereas in the case of God, we do have independent evidence for the existence of a transcendent creator and designer of the universe: Leibniz's argument from contingency, the kalam cosmological argument, Wigner's argument from the applicability of mathematics, the moral argument. So theism is not simply dependent upon fine-tuning but it enjoys independent arguments for its reality, arguments which the multiverse does not share.

KEVIN HARRIS: I think Luke recognizes that. Listen to the continuation of the clip.

DR. BARNES: Fine-tuning can be used as evidence for God. It can be used as evidence for the multiverse. The fact that the multiverse explains it would provide that sort of evidence. I think Craig's reply again to that would be for God we have independent forms of evidence in the form of the other arguments whereas for the multiverse we've got nothing.

KEVIN HARRIS: Well, he predicts . . .

DR. CRAIG: He read my mind! I shouldn't have interrupted you, Kevin.

KEVIN HARRIS: That's fine. These clips can be kind of long so interrupt when you need to.

DR. CRAIG: It was so delicious, I just had to say something! Barnes, I think, correctly anticipated my response.

KEVIN HARRIS: OK. Next he addresses the multiverse generator, as he continues to talk about chance. Here's the next clip.

DR. BARNES: In a particular universe someone was able to measure the mass of the electron in their own universe, what are they likely to observe? Then you've got a prediction for what we should observe. You should be able to do that with the fundamental constants with multiverse theories. The fact that we really can't sort of tells you that a lot of these ideas are kind of toy ideas. But at least there's that possibility. There's another quick one they squeeze in just before the Boltzmann brain one. They say if there is a universe generator then the generator would have to be fine-tuned. I think that's a very good point. The problem is we don't have . . . when we say other laws of physics fine-tuned, other constants of nature fine-tuned, we have the standard model of particle physics, standard model of cosmology, and we can ask questions. There's a definite thing that everyone's looking at. When you say the multiverse, it's not really one thing. It's sort of an idea that there's different ways it might happen. So there's not really “the generator” and then we can go and all look at the generator and see whether it's fine-tuned itself. There's a whole bunch of toy models, if you like.

KEVIN HARRIS: A couple of things there. When he says “toy models” or “toy ideas” do you think he means that they're novel or speculative or kind of wild? Is that what he means?

DR. CRAIG: I think he means they are overly simple. They're simplistic and therefore cannot be realistic descriptions. That's the sense in which these are just toy models of the universe. In his published scientific articles in journals, Luke Barnes has been relentless in pursuing this criticism that these multiverse theories are incomplete, they are unspecified, they don't provide any realistic model of how a multiverse might exist that would explain the fine-tuning. He says until they offer this there's just no credibility to these multiverse theories.

KEVIN HARRIS: He says that we really just don't have a bead on them in order to test some of these things. We just don't have that for the multiverse or a multiverse generator. Which model are you going to talk about, which version are you going to talk about – he says it's kind of vague.

DR. CRAIG: Yes. And notice that if the proponent of the chance hypothesis is to carry the day for his explanation, he needs to show that the multiverse hypothesis will be free of any fine-tuning – that none of its constants and quantities are finely tuned. Because if they are, he hasn't succeeded in explaining it. So he has a real burden of proof to sustain if he's to put his explanation forward as the best.

KEVIN HARRIS: Then he touches on the Boltzmann brain problem in this next clip. Listen to this.

DR. BARNES: The Boltzman brian one – the video makes this point quite well. A smaller amount of order is more likely than a large amount of order. If the multiverse generator is the kind of place that is more likely to make small amounts of order than large amounts, in particular if the way you get a big bit of order is just by getting lots of little bits of order, then it's much more likely that any observer in that universe says, “Oh, you know, I'm just a brain. There's literally chaos like two centimeters outside of my brain cavity. I'm probably going to hang around for about three seconds, so thanks for asking.” Rather than this thing we see where there's order from one end of the universe to the other, 90 billion light years of galaxies and stars and planets. In particular stars that have such useful energy for billions of years, all that sort of stuff. That's the Boltzmann brain problem. It's a very common failed prediction of a multiverse theory that it would predict that an observer should see a small amount of order around them rather than the universe we see around us. So, again, the problem is: are all multiverse theories inflicted by the Boltzmann brain problem? The reason we don't know this is because, again, there's no one thing we're all looking at. There's no one multiverse idea that we can say does this idea . . . If you make a specific model or specific prediction of a specific idea about the multiverse and say, “Here you go. Make some predictions” then we can answer that question. But while it's just a sort of vague “oh maybe a bit of inflation and some string theory comes along even though no one really knows how string theory works” then you can't answer these sort of questions to know whether inflation is fine-tuned. So whether the multiverse itself is fine-tuned and whether it suffers from a Boltzmann's brain problem (although the Boltzmann brain problem does seem to be extremely general).

KEVIN HARRIS: I'm finally starting to understand the Boltzmann brain problem, so if there's anybody listening or watching who doesn't get it yet, you're in good company. But keep on studying it because I think it's fascinating. When he says that it seems to be general, does that mean that it could cover a host of these multiverses, if not all of them?

DR. CRAIG: That’s right. This, I think, is a potentially fatal objection to using multiverse hypotheses to explain away the fine-tuning of the universe. Even if you cannot show that most of the observable universes in the multiverse would be Boltzmann brain worlds and that therefore I am a Boltzmann brain, you can put the conclusion negatively; namely, the multiverse proponent cannot prove that we are not Boltzmann brains with mere illusions of the world around us. He cannot prove that we are ordinary observers who are sensing an external world. In other words, the Boltzmann brain problem leads to a radical skepticism which would leave us without any knowledge of the external world. So whether you state the problem positively (that it implies that we are Boltzmann brains) or you just state it negatively (that it does not show that we are not Boltzmann brains), either way this is a deadly objection to the multiverse hypothesis as an explanation of fine-tuning.

KEVIN HARRIS: This interview is over an hour long, and we've just looked at some excerpts here. Finally, Jordan asked him one more question. Here's number five.

JORDAN HAMPTON: I think that covered the video basically. So once you knock out necessity, chance, all that's left as an option is design. What do you think about that move? Are those the only three options or should there be more?

DR. BARNES: I think that's about right.

KEVIN HARRIS: So there you go. He says, “that's right.” We'll take that. Bill, your summary.

DR. CRAIG: For anybody who knows the scientific literature on fine-tuning, you will recognize that there are three live options to explain it: physical necessity, chance, or design. I think the evidence weighs heavily against both physical necessity and chance, which means that design is the best explanation unless it can be shown to be just as implausible as the other two. Then here the defender of design would need to defend that against potential objections to the design hypothesis.^[4]