Fabric of the Cosmos

Fabric of the Cosmos (part 1)

Dr. Craig examines the contentions of the PBS program "The Fabric of the Cosmos". How do popular science programs often misconstrue science? What philosophical distinctions must be made when dealing with the concept of time?

Fabric of the Cosmos (part 2)

Dr. Craig continues his evaluation of the PBS series and offers theological ramifications that leave Kevin saying "wow!" far too many times!

Fabric of the Cosmos (part 3)

Dr. Craig concludes his discussion of the PBS series by examining aspects of the "multi-verse". And, what in the world is a "Boltzmann Brain?"


Transcript Fabric of the Cosmos Part 1

Kevin Harris: This is the podcast of Reasonable Faith with Dr. William Lane Craig. I'm Kevin Harris. We're going to tackle a very difficult question today, Dr. Craig. There's a new series on Nova for PBS with Brian Greene, The Fabric of the Cosmos – a four part series. It's very well done. The illustrations and the animation were just really well done. They interviewed physicists from all over the world on these topics, and lo' and behold as I watched this series, Dr. Craig, it's a lot of subjects that we talk about right here, and a lot of your work is involved, in particular the meaning and the definition of time, and the universe or a multiverse, and the fabric of the cosmos. What do you think about Brian Greene?

Dr. Craig: I think Brian Greene helps to popularize science for the layman in a dynamic, exciting way that makes it interesting. But what I've noticed about these popularizations of current science, Kevin, is that they all seem to follow a kind of familiar pattern that bothers me. And it's the same pattern that you see in these documentaries every Easter or Christmas about the historical Jesus; namely it's the sensational, the fringe theories, the outrageous views that get all the attention, rather than the good, normal, solid, well-established views. And I think this is because in the media today it's not exciting, it's not interesting, when dog bites man, it's when man bites dog that you get people's attention. And so all of these programs on contemporary popularizations of science seem to try to run the line that modern science is an outrage to common sense, that it's destroyed or called into question all of our normal perceptions about time and reality, and I frankly think that this is just sensationalism, by and large. It is really a misrepresentation of the serious science that's going on here in the favor of attention-grabbing sensationalism, and I think this program is really very guilty of that, frankly.

Kevin Harris: The producers of these programs have to produce a compelling show. They're non-scientific themselves, they're in an editing bay with script writers and they know that they have to get viewers, they have to get laypeople to watch this. It's got to be, as you say, the term is sexy; it's got to be sexy enough to watch. And I guess that many serious scientists are willing to capitulate that in that they, well, first of all, they don't have much of a choice if they're going to be in the program. And second of all, they would like the exposure, and so on. Now I'm not accusing Brian Greene of compromising or anything like that because perhaps his views really have been accurately shown in this piece, in this series.

Dr. Craig: Yes, that could well be. But I think what you discover is that professional physicists many times lack the philosophical training to make the conceptual distinctions that are important, to think clearly about the philosophical implications of these theories, and that's typically what these programs are about. For example, the idea that time is an illusion. That, I think, is a sensationalistic, attention-grabbing claim that has no solid basis in the science but some of these physicists may in fact believe it; others, I think, are simply quoted out of context.

Kevin Harris: Okay, and I'm pursuing this with you, Bill, because I want our listeners to be aware of how programming on TV is produced, in that you have to watch it carefully to see what the producers may be trying to portray rather than the people in the documentary itself. So that's a good point of yours. Alan Guth was quoted in it, and he said: “What is time? It's really the sixty-four thousand dollar question to physics.” And Brian Green says, “What is time? Basically, we don't know.”

Dr. Craig: Yes, now that's the odd thing about it. It begins by saying “Time is a mystery, we don't understand it, we don't know what it is,” and yet by the end of the program we're told that time may well be illusory, that time passes at different rates according to different observers, that the arrow of time is established by thermodynamic entropy increase. All sorts of things are told to us about the nature of time when, at least at the beginning of the program, we were told that time is a mystery which nobody really understands. This is just one of the fundamental contradictions in the whole program.[1]

Kevin Harris: Now there's a difference between the measurement of time and what time is – isn't there? They go through the program on how we began to measure time with pendulums, and things like that.

Dr. Craig: This is exactly, Kevin, one of the conceptual distinctions that needs to be made clearly and that gets blurred in a program like this. It begins by talking about clock measurements. It says no matter how accurate our clocks have become, time remains a mystery; clocks can tell us what time it is, but they haven't been able to tell us what time itself is, what it is we're actually measuring. So they make this distinction between time and our physical measurements of time using clock mechanisms. But then that distinction gets blurred in the program. It begins to talk about how fast time ticks, as time ticks along. Well, now, time doesn't tick along, Kevin. That's a metaphor. Clocks tick, not time. And yet by blurring time with what clocks do then we're told later that time runs more slowly for observers in relative motion to each other, rather than saying that their clocks run more slowly relative to each other. And then you begin to get these statements about the physical time keeping mechanisms applied to time itself.

In fact we shouldn’t even think about time itself as flowing. What we have here in this program is a collision between two radically different views of time that philosophers have helpfully distinguished. One is called a tensed theory of time or a dynamic theory of time; the other is called a tenseless theory of time or a static theory of time. According to the tensed theory of time the distinction between past, present, and future is an objective feature of reality. Temporal becoming is real; that is to say, things come into being and they go out of existence. By contrast on the tenseless view of time the distinction between past, present, and future is just an illusion of human consciousness. Really, all events in time are equally real and the distinction between past, present, and future is just a subjective illusion of human beings. And these two views of time are contrasted without naming them clearly in this program.

And it's important to understand that those who are partisans of the tensed theory of time do not think that time literally flows. This is universally acknowledged among philosophers of time who hold to the tensed view of time to be a metaphor for our experience of time. We experience time as passing, and it passes at different rates experientially depending on whether you're bored (in which case it passes slowly), or if you're busy (in which case time appears to pass quickly). But partisans of tensed time don't think that time literally flows along. Rather they would simply say temporal becoming is real, things come into and go out of existence, and there's a real difference between past, present, and future.

And so what happens in this documentary is that the flow of time is interpreted literally, it is identified with clock rates, and then by saying that clocks run more slowly or more quickly in certain circumstances, that time itself runs more slowly or more quickly. And I think you can see, I hope, that here you've just got an enormous conflation of ideas into this confused muddy waters that need to be made more conceptually distinct.

Kevin Harris: Yeah, and the illustrations didn't really help. You would think that animation and illustration would help in this. But one thing I was thinking was when they showed an instance of a clock slowing down, I thought, okay, now, what is the clock slowing down in reference to? Slowing down in reference to what? The clock may slow down, but you still have a measurement by which to gauge whether it's running faster or running slower that's kind of assumed and in the backdrop. And I thought, okay, well, they're going to bring Einstein into this.

Dr. Craig: Right, because he would say it's running slower relative to some other observer.[2] But what we need to understand is that there are different interpretations of the Special Theory of Relativity. What they're talking about here is the Special Theory of Relativity developed by Albert Einstein in 1905. What they don't tell you is that there are at least three different physical interpretations of the mathematical equations of Special Relativity. The only empirical evidence that we have for the Special Theory of Relativity would establish that the spatio-temporal coordinates of one observer are related to the spatio-temporal coordinates of another uniformly moving observer by a set of equations that are called the Lorentz transformation equations. That is the heart of the Special Theory of Relativity – that the spatio-temporal coordinates of these relativity moving observers are related by this set of mathematical equations named for the great Dutch physicist Hendrik Antoon Lorentz.

But beyond that it's a matter of interpretation how you're to understand this. Einstein's original interpretation was an interpretation of normal three-dimensional physical objects enduring though time. Lorentz's interpretation was quite different. Lorentz said, as you sort of indicated there, there is an absolute time relative to which clocks in motion run slowly, so that when a clock is in motion relative to the sort of fundamental reference frame then that clock will run slowly relative to that frame. But time itself it not relative, as it is in Einstein's interpretation. For Lorentz time itself is unaffected, it's our measurements of time which are affected by motion relative to the absolute reference frame. A third interpretation of relativity theory came along in 1908 from the German mathematician Herman Minkowski, and what Minkowski said in contraction to both Einstein and Lorentz, is that there really are no three-dimensional objects enduring through time, rather objects are four-dimensional. Just as they are extended in the three-dimensions of space – height, width and breadth – they have a fourth dimension in which they are extended, which is the dimension of time. So reality is really four-dimensional, and Minkowski unified time and space into one four-dimensional geometrical representation which he called spacetime.

Now, this program incorrectly attributes the spacetime formulation to Albert Einstein. That is not true. Einstein's original interpretation was an interpretation that had ordinary three-dimensional objects enduring through time, just as Newtonian physics did. The four-dimensional interpretation came along later with Minkowski and after Minkowski developed it Einstein adopted it himself. But that it is Minkowski's interpretation is evident in that the spacetime of Special Relativity is called Minkowski spacetime – it's named after Minkowski, it's not named after Einstein. So what this program is basically doing is plumping for a four-dimensional Minkowskian interpretation of the Special Theory of Relativity rather than the original Einsteinian view or a Lorentzian view.

Now, the problem is, Kevin, that these three physical interpretations are empirically equivalent. At least until very recently there's been no way to discover which one of them is correct because they all make the same empirical predictions. And yet Greene and some of the other persons in the program present the sort of textbook Minkowskian view of relativity theory as though this were in fact the truth, as though this were a scientific discovery, and it's not. And if I might here, I want to quote from an article that we did a podcast on on another occasion – an interview with professor Tim Maudlin, who is a very eminent contemporary philosopher of time. He speaks to this very issue. He says that,

You have others saying that time is just an illusion, that there isn't really a direction of time, and so forth.[3] I myself think that all of the reasons that lead people to say things like that have very little merit, and that people have just been misled, largely by mistaking the mathematics they use to describe reality for reality itself.[4]

Now that is a perfect characterization of Minkowski spacetime. Minkowski discovered that you can formulate the theory by imagining this four-dimensional geometry called spacetime, but people have elevated this mathematical representation to realty. They think that spacetime is not just a sort of diagrammatical way of portraying space and time on an axis, rather they think that this is reality, this is the way the world really is. And as Maudlin says, that is a philosophical or metaphysical jump or leap which has no justification in the science at all. It is an uncritical, naïve – philosophically naïve – interpretation of Minkowski spacetime, to be not just a diagrammatic way of representing reality but to be a sort of picture of reality itself. So Maudlin says, to answer “Why should physicists want to hand the subject of time over to philosophers?”:

The answer would be that physicists for almost a hundred years have been dissuaded from trying to think about fundamental questions. I think most physicists would quite rightly say, “I don't have the tools to answer a question like, 'what is time?' – I have the tools to solve a differential equation.” The asking of fundamental physical questions is just not part of the training of a physicist anymore.[5]

So these are deep metaphysical questions which contemporary physicists are very ill-quipped to adjudicate.

Kevin Harris: Now, Bill, let me understand that one of your complaints here is that this particular series, The Fabric of the Cosmos from PBS and Nova, only presents the tenseless view of time, not the tensed view. It's a B-theory of time that they want to embrace.

Dr. Craig: That's another name for the tenseless theory, the B-theory of time; whereas the tensed view has been called the A-theory of time by philosophers.

Kevin Harris: A and B; okay.

Dr. Craig: Yes. And what it does is present the B-theory as though it has been established by these breakthrough discoveries in science that show that temporal becoming is illusory. They draw these vast metaphysical conclusions like the past, present, and future are equally real, and that tense is an illusion of human consciousness. As Maudlin says, these are all gratuitous. There are perfectly good interpretations of the equations that involve a tensed theory of time, including Einstein's original view in 1905 as well as Lorentz's view.

Kevin Harris: Brian Greene says that “Einstein would shake up the world with a radical insight into the nature of time.” He said, “Most people view time in a pretty simple straightforward way, time ticks the same for everyone everywhere.”

Dr. Craig: Yeah, see, the ticking; the conflation of clocks with time itself.

Kevin Harris: He says, “It's a commonsense picture established by the father of modern science, Isaac Newton.” But he goes on to say, “Sensible as Newton's picture of time may seem, Einstein realized it wasn't right. He discovered that time could run at different rates. As strange as it sounds, this means that time for me may not be the same as time for you. Einstein's discovery smashed Newton's conception of reality.” Now, that's what we've been talking about, Bill.

Dr. Craig: Sure; that's what we've been told.

Kevin Harris: Okay, so it's an embrace of one particular view out of the three of relativity, and also an embrace of the one particular view out of two views of time, the A-theory and the B-theory.

Dr. Craig: Yes, that's right. That's right, in favor of this sort of tenseless theory. And what's interesting, Kevin, is that he doesn't mention in this program that some of the most recent scientific evidence that's very exciting tend to vindicate Lorentz's interpretation, that there is absolute time and a sort of fundamental reference frame. And what I'm having reference here to is the measurement of faster than light particles at the accelerator in CERN in Switzerland. They have measured neutrinos traveling faster than the speed of light, and if there are such particles traveling at super-luminal velocities, on Einstein’s interpretation and Minkowski's this would mean that relative to some reference frames, these particles would go backwards in time. That means that the particle would literally be received at the receptor before it was ever sent from the transmitter, which is absurd.[6] So if you're going to avoid these sort of pathological situations what you have to say is that there is an absolute reference frame relative to which these super-luminal particles are moving, just as Lorentz believed, and that they do not go backwards in time at all, but that our clocks and our measuring instruments are affected by their motion relative to this absolute reference frame. So these recent discoveries actually fit very much better with a Lorentzian interpretation of relativity than the received view.

Kevin Harris: Bill, so often programs like this and physicists want to embrace the more mysterious, absurd notions; and you go, “That's absurd!” They go, “Ah, of course.”

Dr. Craig: Yes, exactly. This is what bothers me; it's the sensationalism.

Kevin Harris: It's the sound of one hand clapping. That's absurd. “Ah, now you understand.” [laughter]

Dr. Craig: Or it reminds me again of these historical Jesus programs where it's the apocryphal gospels, the gospel of Judas, the DaVinci Code, these flaky views that get all the attention because they're sensational. There seems to be a certain sort of standard shtick here in these science programs that the more they outrage common sense the better when in fact that's not at all required by the science.

Kevin Harris: By the way, the B-theory of time is a lot sexier than the A-theory of time because on the B-theory you can travel back in time – time travel is possible.

Dr. Craig: Right, that comes in on this program too, doesn't it?

Kevin Harris: It does in some of the illustrations. So it's more entertaining. I'm just trying to say that you can, wow, you can go back to the first grade!

Dr. Craig: Yes, though it has some, I think, absurd results. For example, if people are actually four-dimensional objects that are extended in time then the person that I see sitting across the table from me here – you – you're really not that whole object, you're just a slice of that object. You're like a slice of the loaf of bread. But what that means then, Kevin, is that the person I'm speaking to now is not the same person that was there one second ago because it's a different slice. So these are literally different objects. Now that means you're not the same person as the one who began listening to this program a few minutes ago. You are literally a different person. There is no personal identity over time on this tenseless theory, which I think is outrageous; it's just absurd. So I think there are all kinds of philosophical problems with this tenseless view that make it highly implausible.

Kevin Harris: We have run out of time. It has flown past, and we want to pick this up next time. In fact, Bill, on our next podcast, there's an illustration of what we're talking about that they do on this particular show. They use the animation of a person and an alien from another planet that they attempt to show that in fact the tenseless view of time, the B-theory, is the correct one. We'll look at that next time right here on Reasonable Faith.[7]



[1] 5:02

[2] 10:03

[3] 15:00

[4] Ross Andersen, “What Happened Before the Big Bang? The New Philosophy of Cosmology,” The Atlantic, January 19, 2012. See http://www.theatlantic.com/technology/archive/2012/01/what-happened-before-the-big-bang-the-new-philosophy-of-cosmology/251608/ (accessed March 19, 2014).

[5] Ibid.

[6] 20:07

[7] Total Running Time: 23:30 (Copyright © 2012 William Lane Craig)


Fabric of the Cosmos Part 2

Kevin Harris: Welcome back to the podcast of Reasonable Faith with Dr. William Lane Craig. We've been talking about the PBS series Nova and The Fabric of the Cosmos with Brian Greene of Columbia who also studied at Cornell. A really well-made documentary, Bill, but you've had your reservations about it. Sometimes glossy productivity and compelling images don't necessarily tell the truth. And at the end of our last podcast you talked about this theory that if you're looking at me you always see a slice of me, a kind of 'now' slice. This documentary says that that's kind of what Einstein came up with, that you can slice time, or slice spacetime just like you would slice a loaf of bread.

Dr. Craig: Einstein didn't come up with this idea but he did adopt it after Herman Minkowski came up with it in 1908. Minkowski was a German mathematician who realized that Einstein’s Special Theory of Relativity could be formulated in a more perspicuous way by thinking of space and time as geometrical and representing objects as being four-dimensional, as having three dimensions of spatial extension and one dimension of temporal extension. And so what we see in our experience around us on Minkowski's representation would just be a slice, a three-dimensional slice or cross-section, of an extended four-dimensional spacetime worm.

Kevin Harris: Brian Greene says,

To get a feel for the bizarre effect this can have imagine an alien in a galaxy ten billion light years from earth and way over there on earth the guy at the gas station. Now if the two are sitting still, not moving in relation to one another, their clocks tick off time at the same rate, and so they share the same 'now' slices, which can cut straight through across their loaf. But watch what happens if the alien hops on his bike and rides directly away from earth. Since motion slows the passage of time, their clocks will no longer tick off time at the same rate, and if their clocks no longer agree their 'now' slices will no longer agree either. The alien's 'now' slice cuts across the loaf differently. It's angled towards the past. Since the alien is biking at a leisurely pace his slice is angled toward the past by only a miniscule amount. But across such a vast distance that tiny angle results in a huge difference in time. So what the alien would find on his angled ‘now’ slice he considers is happening right now on earth, no longer includes our friend at the gas station or even forty years earlier when our friend was a baby. Amazingly, the alien's 'now' slice has swept back through more than two-hundred years of earth history and now includes events we consider part of the distant past, like Beethoven finishing his fifth symphony, 1804-1808.

Okay, now this illustration is supposed to show that since their two now slices – the 'now' slices that they inhabit – the alien's is so far away in a moving relation to each other that it's going further back, that he's two-hundred years in the past from the guy on earth, and that would make it possible to be able to go, or maybe traverse that back to two-hundred years.

Dr. Craig: Well, now, that in itself wouldn't enable time travel to be possible. But what he is describing here is how, on the Special Theory of Relativity, if you use Einstein’s procedure for synchronizing different clocks then you will calculate different events to be simultaneous with each other. It's not really a 'now' slice, as he puts it – he's combining there a tensed view of time with a tenseless view of time – it's really, what events does the alien consider to be simultaneous with his current event, and what event does the man at the gas station consider to be simultaneous. And using Einstein’s procedure they will determine different events to be simultaneous with the event that they are engaging in at that time. Now, does that imply, then, that there is no absolute now or no absolute time?[1] Well, not at all. On Lorentz's view it's their clocks that are affected by their relative motion. And so Einstein’s clock synchronization procedure will be incorrect with regard to observers who are in relative motion. It will only apply to someone who is at rest with respect to the fundamental reference frame of absolute space. So on Lorentz's view it is our clocks which are affected by a relative motion, not time itself.

Kevin Harris: Sean Carroll says, “If you believe the laws of physics, there is just as much reality to the future and the past as there is to the present moment.” Max Tegmark then says, “The past is not gone, and the future isn't non-existent. The past, the future, and the present are all existing in exactly the same way.”

Dr. Craig: That is an expression of this Minkowskian view of spacetime. It is a gratuitous metaphysical inference from this geometrical representation of time and space.

Kevin Harris: A model.

Dr. Craig: Yes, a model, or almost, really, even a diagram. You could do the same thing with temperature and pressure, for example. You could draw a chart where one axis represents pressure and the other axis represents temperature, and you could draw a line of how the temperature-pressure goes, as the temperature increases or the pressure increases, say. But that doesn’t mean there's a reality called 'temperature-pressure.' It's just a way of representing it on paper, and it's almost that bad with respect to spacetime. They have taken a diagrammatical way of representing time and space and interpreted this to be reality. Now that certainly is a possible interpretation of the theory. Indeed, it is a metaphysical view of reality that is breathtaking – I think Einstein was a philosopher as well as a physicist. It is a breathtaking vision of reality, this tenseless theory of time. But the idea that you just read this off of modern science is illusory; that is simply not the case.

Kevin Harris: Let's use Brian Greene's illustration here to see if we can illustrate A-theory and B-theory. Brian Greene says,

Just the way an entire movie exists on celluloid, think of all moments of time as already existing, too. The difference is that in the movies a projector lights up or selects each frame as it goes by. But in the law of physics there is no evidence of something like a projector light that selects one moment over another. Our brains may create this impression, but in reality what we all experience as the flow of time really may be nothing more than an illusion.

Now, time (the whole history), and in fact the future, is in that film case with a handle on it. It's the celluloid with each frame coiled up.

Dr. Craig: Representing a different moment of time

Kevin Harris: Then as it goes across the projector, we experience each moment of time.

Dr. Craig: As present.

Kevin Harris: Now, the A-theory of time, then, Bill, using this illustration, there wouldn't be the whole case full of the celluloid, there would be one cell after, one frame after another.

Dr. Craig: Exactly. Those future frames don't exist. There is no sense in which my eating dinner tomorrow is out there somehow down the line equally existent with what is happening right now.

Kevin Harris: That's what this program said though. [laughter]

Dr. Craig: Yes, it does say that, Kevin. It is doing metaphysics. It's doing metaphysics but passing it off as physics. And I think that's what troubles me so much.

Kevin Harris: Okay, you've shown us one distinction to make: and that is don't misinterpret models and diagrams which are mathematical tools to work on these things as somehow instantiating them.

Dr. Craig: Yes; and I'd like to speak to the issue of the movie film being shown on the screen, as well. Greene says there is nothing that corresponds to the light of the projector in reality. Well, I disagree with that. And I think what it is is what philosophers call the presentness of experience. The presentness of my own experience, I think, is that projector light. I can be mistaken about the presentness of other events out there because those events are mediated to me by finite velocity light signals.[2] And so when you view the supernovae through the telescope you think it's occurring right now as you see it, but in fact it occurred millions of years ago because it's taken the light that long to get to you. But I can't be mistaken about the presentness of my own experience. That is, my experience of seeing the supernovae is now. And there is nothing that will eliminate the presentness of experience. Even if you say that the experience of temporal becoming is illusory, the illusion of temporal becoming itself involves temporal becoming. The very illusion of it involves a presentness of the illusory experience. So I think there most certainly is a sort of privileged present which we immediately grasp in the presentness of our experience. And the fact that different observers moving relative to each other will calculate different events to be present is simply a distortion of their measuring instruments, of their clocks.

And I might say here, too, that it's very misleading when theorists will sometimes say that this other observer, like your alien, that he will observe some other event to be present. That's not true. We're not talking about observation here, Kevin. What you're talking about is mathematical calculation. He will calculate, using the Lorentz transformation equations, the spatial-temporal coordinates of some distant event and he will determine different events to be simultaneous than someone who's moving relative to him. But it's all just a matter of mathematical calculation; it's not empirical observation. And so with regard to the empirical evidence these two different interpretations of the theory are entirely equivalent, apart from these recent discoveries that I mentioned in our other podcast at CERN where we seem to have discovered superluminal particles that would suggest an absolute reference frame.

Kevin Harris: Well, whenever I hear that something is an illusion that always perks my ears up, Bill, because if you say something is an illusion, you're assuming a backdrop of reality by which to compare the illusion. You don't know what an illusion is unless you know what's not an illusion. You don't know what an illusion is unless you know what the real is. And so I was trying to figure out, just like how the clock slows down in reference to one – well, okay, now, what is the backdrop of reality by which this is gauged as an illusion?

Dr. Craig: Yeah. I think that they would say it is this four-dimensional spacetime.

Kevin Harris: Okay.

Dr. Craig: These folks are realists about spacetime. They think that there really is this four-dimensional entity called spacetime and we are occupying different spatial-temporal coordinates in it. And the idea that there is a present is just an illusion of our consciousness.

Kevin Harris: And this program then goes on into time travel in the past and in the future.

Dr. Craig: Right. Without alerting the viewer, the program moves from talking about the Special Theory of Relativity into the General Theory of Relativity, and these are very different. And it's really important to make the distinction because Einstein’s Special Theory of Relativity didn’t really succeed in showing that all motion is relative. He just dealt with uniform motion or constant speed in the special theory. But accelerated motion or rotational motion is still absolute. And in the general theory he tried to provide a theory of relativity that would show even accelerated or rotational motion is just relative, too. And he failed; he was unable to do so. So the General Theory of Relativity is really a misnomer, Kevin. It's not a relativity theory. What it is is a radical new theory of gravity – it is a gravitational theory. And in it he says, in fact, that Minkowski spacetime, the spacetime of Special Theory of Relativity, doesn't really exist. The spacetime in the Special Theory of Relativity is flat, it doesn't have any curvature. In the General Theory of Relativity spacetime is represented as curved, and the presence of matter in spacetime will warp spacetime, if you interpret it realistically. And so you're dealing with a very different theory, and in fact it turns out that all these conclusions in the special theory turn out to be in a sense false because they only apply in a flat spacetime,[3] and that's not the way spacetime is. Spacetime is, in fact, curved. And when you look at the General Theory of Relativity and you apply it to cosmology, what happens, Kevin, is that there turns out to be a sort of preferential way of slicing up the loaf of spacetime. Now, it's true, you could slice up spacetime any way you want in general relativity, but there is only one slicing in which you will have an expanding universe that expands in a way that will be the same in all directions, that will preserve the homogeneity of matter, right back to the initial Big Bang. So it turns out that there is a preferred slicing of spacetime in modern cosmology, and what this gives you, Kevin, is a cosmic time which is the same for every observer in the universe regardless of his relative motion.

Kevin Harris: Wow.

Dr. Craig: Yeah, exactly. Wow, you're right. In other words, what this does is this restores that universal, absolute time that was supposedly done away with in the special theory. It reemerges in the general theory with cosmic time which is the same for all observers in the universe. So when cosmologists say that the universe originated 13.7 billion years ago in the Big Bang, they're not qualifying that by saying, “from our frame of reference,” or, “it's 13.7 billion years from our perspective.” No, this is a cosmic time that measures the duration of the universe, and is the same for every observer in the universe. So you do have that fundamental, absolute, universal time that Newton believed in and that Lorentz believed in, and the rug is pulled out from underneath those who want to say with the special theory that there is no sort of preferred and absolute universal time.

Kevin Harris: Bill, as we conclude this today would you reflect a little on the theological and apologetic ramifications of what we've been talking about.

Dr. Craig: Well, I think there are such ramifications, Kevin. I got into this subject because I was interested in God's eternity, God's relationship to time. Many philosophers and theologians think that God is in time, that God has a past, present, and future. But then the question obviously arises, well, if God is in time, who's time is he in? Since God isn't a physical object in relative motion he couldn't be identified with the reference frame of any physical observer in the universe. There would be no reason to privilege one of these frames, to think that that's God's time. So, who's time is God in? He couldn’t be in everyone's time because then he would have a fractured consciousness. He wouldn't know what time it is. He would have all of these diverse 'now' consciousnesses and wouldn't know what is actually happening now. And so you would get a sort of schizophrenic God that would almost look like polytheism, a different one associated with each reference frame.

So it seems plausible that if God is in time that there is a kind of absolute time that is his now, and that he knows what events he is now causing throughout the universe. If God sustains the universe in being moment by moment then he knows immediately without any need of clock synchronization procedures what events he is now causing in the universe. And so that would give you a kind of absolute time, just as Lorentz thought.

And so I think that a Lorentzian view of special relativity theory fits in very nicely with the view that God is in time. Moreover, the cosmic time that emerges in the General Theory of Relativity would be the measure of the duration of the universe from the time that God created it. In other words, the universe would be literally a clock; it is God's clock that measures the time since God created the universe. So this is a really remarkable, I think, theological implication of this.

I think it also has other implications. For example, if temporal becoming is just an illusion and there is no objective distinction between past, present, and future,[4] then that means in a sense, Kevin, that evil is never really eliminated from reality. It would just mean that earlier portions of the spacetime block are filled with evil events, and that later portions of the spacetime block after God judges evil are now no longer filled with events that are morally evil. But those morally evil events never really pass away. The stain of evil is indelible and is just as real as the later portions of the block. In particular, Christ's hanging on the cross is just as real as later slices of Christ that are risen from the dead. In one sense the Christ that is on the cross never really comes down. That slice is never raised from the dead, it's permanent.

Kevin Harris: Wow.

Dr. Craig: So this has really very strange implications for evil and God's victory over evil. Think of what it also means for God's judgment of persons. I shared earlier that when I interact with you I don't really see you, what I see is a temporal slice of you. I see a piece of you, a three-dimensional cross-section of you. So when people stand before God on the Judgment Day and God judges them, by what right can he judge those temporal slices that stand before him on the Judgment Day because of what other temporal slices did in the past? They're the ones who ought to be punished, not the one that's standing before him on the Judgment Day.

Kevin Harris: Wow.

Dr. Craig: And, similarly, those that are standing before him on the Judgment Day, really, there's an infinite number of slices there because all you have to do is ask yourself, well, how big of a slice do you want to take? A one year slice, a one second slice, a one minute slice? All of those slices are present before God on the Judgment Day but yet not all of those slices are equally guilty of the same sins or the same good deeds. So it makes moral praise and blame impossible because you can't morally reward and blame one slice for things that are done by literally another object, another slice.

Kevin Harris: Wow.

Dr. Craig: So this tenseless theory of time, I think, has all sorts of really strange and undesirable theological consequences that would give us good reason to reject it unless there were some sort of overwhelming philosophical or scientific evidence in favor of the four-dimensional view. But there's not, Kevin. There are no good philosophical or scientific arguments for adopting this tenseless four-dimensionalist view of reality.

Kevin Harris: What kind of affect does it have on the kalam?

Dr. Craig: I think that the kalam cosmological argument from start to finish is predicated upon a tensed theory of time because when we say that everything that begins to exist has a cause we mean that something can't come into being without a cause. On the tenseless theory, however, things never really come into being. They just exist at their appointed spatial-temporal stations. So on the B-theory the universe begins to exist only in the sense in which a yard stick begins to exist, namely, there's a front edge, there's a first inch, but it doesn't come into being at that point. So the tenseless theory of time would make it inappropriate, I think, to ask, “Why did the universe come into being?” It didn't. It just exists eternally and timelessly. The question that would be asked, I think, on the tenseless theory of time would be Leibniz’s question: Why is there something rather than nothing? Why does this four-dimensional spacetime block exist, instead of just nothing?

Kevin Harris: Still you can't escape Leibniz. [laughter]

Dr. Craig: No, you can't escape Leibniz. But without the tensed theory of time I think the kalam cosmological argument would no longer have the force that it does.

Kevin Harris: I really need to get this time thing down. I can't be on time anywhere I go, [laughter] I am late everywhere. And so thank you, Dr. Craig, for this. Next time we want to continue looking at The Fabric of the Cosmos and there's one particular series we're going to look at: the universe or the multiverse? That's next time right here on Reasonable Faith.[5]



[1] 5:03

[2] 10:03

[3] 15:08

[4] 20:05

[5] Total Running Time: 24:55 (Copyright © 2012 William Lane Craig)


Fabric of the Cosmos (Part 3)

Kevin Harris: Thanks for joining us on Reasonable Faith with Dr. William Lane Craig. Dr. Craig, we've been looking at The Fabric of the Cosmos with Brian Greene, produced by Nova for PBS, really well-done, and, yet, we've also tried to uncover some of the hidden agendas and assumptions of this series. When we look today at this particular segment of the series – universe or multiverse? – what are some of the overriding views that are held that flavor and color this one?

Dr. Craig: Well, what this program is really about, Kevin, is the problem of the fine-tuning of the universe for intelligent, interactive, embodied agents, like ourselves. I don't believe the word fine-tuning is actually mentioned in the program, but instead he talks about the dark energy that pervades the cosmos and which has a very precise life-permitting value, and how can you explain this apart from some sort of cosmic intelligence which has designed the universe to be life-permitting? So that would be the cash value, theologically, for the question that he's asking – universe or multiverse? – because those are, in a sense, the options for explaining the fine-tuning. He might have entitled this: universe, multiverse, or God? But God doesn't get into the pool of explanatory options in this program.

Kevin Harris: Well, this is the newest kid on the block – multiverse. And I think that, not only does this series embrace it, but Brian Greene certainly does – the multiverse.

Dr. Craig: Yes, this has become the center of the debate over fine-tuning today. The principle alternative to a cosmic designer is some sort of multiverse or world ensemble or many worlds hypothesis in order to give you the probabilistic resources for our highly improbable fine-tuned universe to exist. If you have many roulette wheels rolling at once then you'll increase the probability that one will come up in a particular number than if there's just one wheel that's turning. And so the multiverse is an attempt to get as many roulette wheels turning as possible in order to get this highly, highly, improbable result that we observe.

Kevin Harris: I see that move, and that would be fine and dandy if it were true.

Dr. Craig: Yes, that's right. It would work if it were true.

Kevin Harris: Stephen Weinberg says, “if the multiverse is indeed infinite then one is going to have to confront a lot of possibilities that are very hard to imagine.” So he's captured our imagination there, an infinite multiverse?

Dr. Craig: That the multiverse is infinite is not something that's required by the multiverse hypothesis. That's a sort of ad hoc adjustment that needs to be made by hand. You've got to get an infinite number of these universes in order to guarantee that our universe will come up by chance somewhere in the multiverse. If there's only a finite number of universes in the multiverse then it's not guaranteed that ours would appear anywhere by chance. So many times theorists will say, well, there's an infinite number of multiverses. Now that is a breathtaking metaphysical hypothesis, Kevin, that there's an infinite number of multiverses.

Now, how they get that is very interesting, too, because it involves, again, a commitment to a certain metaphysical view of time. What they do is they interpret universes which are future relative to us to be actually real and existent. So that if these universes keep on coming into existence into the future then all of those can be counted as equally real and existent. And that's how you get your infinite number of universes – by counting these ones that are in the future as though they actually exist. Well, the problem is that presupposes this view of time according to which there is no objective distinction between past, present, and future. If you say that temporal becoming is real then universes that will form in the future are pure possibilities.[1] They're mere potentialities. They in no sense exist. Therefore you would not have your infinite number of roulette wheels spinning right now, and therefore there would be no guarantee that we would exist right now.

The point that I'm making here, Kevin, is that the postulate has to be a lot more than just saying there are other worlds, there are other universes. This has got to be adjusted so, number one, they've got to be infinite in number if you're going to guarantee that our universe will appear some place, you've got to postulate a certain number of these; but then also you need to postulate that they're randomly ordered in their constants and quantities, because if they're just all the same, or, say, if there are only three kinds of universes in the multiverse then there's, again, no guarantee that ours would appear anywhere by chance. So the hypothesis is a lot more finessed than just saying, 'maybe there are other worlds.' You're postulating the existence of this infinite number of randomly ordered unseen universes out there just in order to explain away the fine-tuning of our universe that we observe.

Kevin Harris: Andreas Albrecht of the University of California says in this series, “I'm very uncomfortable with the multiverse. To become solid science it's got a lot of growing up to do.”

Dr. Craig: Yeah, it looks very metaphysical at this point. It's a metaphysical hypothesis because there isn't any physical evidence that there are other universes. Now, I think it would be good at this point to say, Kevin, that the theist doesn't have any objection in principle to there being a multiverse and there being other universes. We would say that even that multiverse was brought into being by God. In fact, I think, Kevin, and this will emerge in the course of this podcast, really, the best hope for the existence of a multiverse is theism. I don't see much hope for thinking that there is a multiverse if naturalism is true. I think the best hope of saying that there is a multiverse is that God has created it and brought into being many worlds. So there's nothing inherently anti-theistic about this. We have no ax to grind in this discussion. We can be open to follow the evidence where it leads.

Kevin Harris: And we would also be in line with Genesis 1:1, in the beginning God created the heavens and the earth, in that the multiverse would also require a beginning, according to the models.

Dr. Craig: Yes, we've talked about that in other podcasts, that the theorem that was developed by Alexander Vilenkin and Alan Guth and Arvind Borde applies to this multiverse, not just to our universe. And the multiverse itself would have to have a finite past and therefore a past spacetime boundary. It cannot be eternal in the past; it too came into existence. So Vilenkin has recently said that all the evidence says that the universe has a beginning, and by that he means all that exists spatial-temporally.

Kevin Harris: You can always count on Star Trek to have examined some of this on the TV series. But I seem to recall one episode in which there was a universe in which an evil Spock existed, and he had a goatee, you know, kind of sinister looking, and he was mean, and he encountered the good Spock without the goatee. And really that's a simplified version of what this speculation is on multiverses, that somewhere there is a Bill Craig who was a dentist as opposed to a philosopher in a universe somewhere.

Dr. Craig: Yes, the idea there, Kevin, is that if you have a finite number of possibilities and you have an infinite number of universes then every possibility will be actualized some place. I don't think that that at all follows because for someone who believes in freedom of the will, events don't happen just by random chance. Events happen because people choose things for good reasons. And so there may be no world, no universe, in which, for example, Adolf Hitler delivers the Nuremberg Address standing on his head. There's no reason he would do such a thing. So even though that's physically possible, there's no reason to think that even in an infinite multiverse that that event takes place somewhere. Why? Because events don't just happen according to random chance if there are libertarian agents who make significant choices that's going to mess up the calculations.[2]

Kevin Harris: Well, Bill, this program seems to hint at the multiverse being eternal, and we've said that Vilenkin has shown that that's not right. It then goes to dark energy. What do we mean by dark energy?

Dr. Craig: The dark energy is postulated to explain the recently observed acceleration of the universe. Rather then slowing down the expansion of the universe actually seems to be speeding up. There seems to be a repulsive force or dark energy that is blowing the universe apart at ever more rapid speed. And this dark energy is finely-tuned to our existence to the measure of about one part out of ten to the hundred and twentieth power, an inconceivable precision. If it were slightly greater then everything would blow apart so quickly that galaxies and stars and planets would never even have formed. So the dark energy is fine-tuned for the universe to permit intelligent, interactive, embodied agents to a degree that is literally incomprehensible. This is just on example of many examples of fine-tuning of the universe, and this program appeals to dark energy as one reason to adopt a multiverse hypothesis. Now, that's really interesting, Kevin, because they don't call it fine-tuning, but that's really what it is. This is just an instance or an illustration of fine-tuning. What they're really saying is that to explain the fine-tuning of the universe for life we need to appeal to this multiverse hypothesis in order to multiply the probabilistic resources so that somewhere in this world ensemble of universes one with just this value of the dark energy would turn up by chance alone.

Kevin Harris: Yeah, and Brian Greene says it. He says in this series:

The value of the dark energy wouldn't allow the formation of galaxies, stars, and planets. Universes with much less dark energy than ours would just collapse in on themselves. And universes with much more dark energy than ours would expand so fast that matter would never have a chance to coalesce into clumps and form stars and galaxies.

So that is the fine-tuning, isn't it? We're in a Goldilocks region of dark energy.

Dr. Craig: Yes.

Kevin Harris: Now, was dark energy predicted? Because I guess you would think that the expansion of the universe would slow down after the Big Bang.

Dr. Craig: Yes, for years scientists were trying to measure what's called the deceleration parameter of the universe. They thought that they could show that as the expansion moves out that it would slow down, and instead it's speeding up.

Kevin Harris: And so we have to say, okay, now why, against what we would think, is it speeding up? You'd have to postulate something like dark energy.

Dr. Craig: Yes, that's right. And this dark energy is then fine-tuned for life, for life to exist.

Kevin Harris: Is dark energy a tool or is there really experiential evidence that the dark energy is there and is pushing galaxies away?

Dr. Craig: Well, it's a name. Dark energy, in the sense that you can't observe it visually. But it's a name, but there is a real repulsive force that is blowing the universe apart at ever-accelerating speed.

Kevin Harris: By the way, that seems to indicate that we're not going to experience a big crunch.

Dr. Craig: That's what it seems to indicate. It seems to indicate that as time goes on the universe will just expand forever and will never re-collapse.

Kevin Harris: I don't want to be crunched, so I'm glad. [laughter] Of course, I know how it turns out. So the dark energy is used as an evidence that there might be a multiverse. What else do they go to here?

Dr. Craig: Well, he not only appeals to the fine-tuning of the universe but he also appeals to inflationary models of the universe and to string theory. Now both of these are extremely speculative and underdeveloped areas of science but that doesn't stop him from appealing to these to generate the multiverse. Here's the problem. In string theory it doesn't predict that the universe should have the precise values of these various constants that we observe, like the gravitational constant or the electromagnetic force. In fact it is consistent with the laws of physics and with string theory that there would be around ten to the five-hundredth power different possibilities for universes governed by our laws of nature.[3] So string theory doesn't do anything to make the observed values of these constants necessary. That would seem to be friendly to the fine-tuning argument. It would show that fine-tuning is not due to physical necessity. String theory does not predict that these constants will have the values they have by physical necessity. It permits a wide range of values, ten to the five-hundredth power different sorts of universes. And this has come to be called the cosmic landscape, which has become a sort of phenom in it's own right. Now, it's important to understand, this cosmic landscape is just a landscape of possibilities, Kevin. These aren’t real worlds or real universes out there, it's just possibilities. But the attempt, then, is to marry string theory with inflationary theory, which says that our universe may be a bubble within a wider universe which is blowing up, which is expanding, a sort of mother universe. And in this mother universe that is blowing up different bubbles will form here and there and these represent different universes. So if you marry string theory with inflationary theory you can say that inflation gives you the many bubbles – right? – and the string theory gives you the random variation of the universes among the ten to the five-hundredth possibilities. And so this is how you'll get your multiverse, based upon string theory and inflation. And the problem, of course, is that this is all conjectural. Nobody has any idea whether or not this is true. There's no evidence that there is such a world ensemble out there. But this is the attempt to generate the multiverse that could then give you the probabilistic resources to explain the observed fine-tuning.

Kevin Harris: Bill, let's conclude today with some evidence against this whole multiverse notion.

Dr. Craig: Yes, I think that is important to rehearse because a number of physicists, such as Roger Penrose at Oxford University, have been highly critical of these attempts to explain fine-tuning by appealing to a multiverse hypothesis. And one of the most critical problems is the problem that's been called the invasion of the Boltzmann brains. Boltzmann brains are brains named after the famous German physicist Ludwig Boltzmann which just fluctuate into existence out of the quantum vacuum. They represent random fluctuations of the vacuum. And these fluctuation-formed brains, then, are observers. This would be an observable universe. A Boltzmann brain could have an observation of the universe in which it exists for a fleeting amount of time. What that means, therefore, Kevin, is that in order for universes to be observable they don't have to be fine-tuned for agents like ourselves. Indeed the most probable sort of observer that would form by chance in a multiverse scenario would be these Boltzmann brains, so that they would dominate the proportion of observable universes. If there is a multiverse then the most probable sort of observable universe by far would be a universe that has a single Boltzmann brain that fluctuates into existence.

What that means, therefore, Kevin, is that the fine-tuning of the universe that we observe for intelligent, embodied, interactive agents cannot be explained away by just saying, “Well, in a multiverse it would have to happen somewhere.” Because given a multiverse hypothesis, it is vastly more probable that what would exist would be a Boltzmann brain observable universe, and not a universe like ours. So the fine-tuning cannot be explained away as simply a self-selection effect of observable universes. There are observable universes that are not fine-tuned like ours, indeed they are vastly, vastly more probable, and therefore should exist if there is a multiverse.

So what that means, I think, is that the evidence indicates that in all probability there is no multiverse out there because we don't have a Boltzmann brain universe,[4] we've got a different kind of observable universe, and therefore that disconfirms very strongly the multiverse hypothesis.

Kevin Harris: So when you say observable universe, the observable universes that exist, are you talking about possible universes?

Dr. Craig: Yes, universes that would have observers in them.

Kevin Harris: There you go; there you go; okay.

Dr. Craig: Think of the multiverse. Most of the multiverse is dead – right? Most of the multiverse has no observes. But by chance alone there will appear observers in some of these universes. And the point I'm making here, and that others have made, is that the incomprehensible majority of those observable universes will be Boltzmann brain worlds, and