Fabric of the Cosmos (part 2)

Transcript 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,

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,

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]