Tim Maudlin's Interesting View of Time Part 2November 09, 2017 Time: 21:45
The renowned philosopher takes a more traditional view of time.
KEVIN HARRIS: Welcome back to Reasonable Faith with Dr. William Lane Craig. We are continuing to look at this interview with philosopher Tim Maudlin on the nature of time. And when you get time be sure to go by our website. It's new! We have some new features at ReasonableFaith.org. Go there often. We appreciate you supporting this ministry. And you can do that through our website safely and easily at ReasonableFaith.org. Here is part two of our podcast series on Tim Maudlin and time.
Bill, real quick – a quick side road – why would it be more possible to time travel on a B-theory of time then on an A-theory?
DR. CRAIG: I think simply because on the B-theory of time the future is just as real as the past whereas on the A-theory of time there is no such thing as the future. It doesn't exist. So it is impossible to travel from there to here.
KEVIN HARRIS: Tse then asks him,
If time has a direction, is the thermodynamic arrow of time still a problem?
Dr. Maudlin says,
The problem there isn’t with the arrow. The problem is with understanding why things started out in a low-entropy state. Once you have that it starts in a low-entropy state, the normal thermodynamic arguments lead you to expect that most of the possible initial states are going to yield an increasing entropy. So the question is, why did things start out so low entropy?
DR. CRAIG: This is highly significant. What Maudlin, I think, is implying is that thermodynamics does not give time its arrow. He said that time has a direction, right? That is called the arrow of time. There is a directionality to time from earlier than to later than. What he is saying is that thermodynamics, namely the claim that entropy increases over time, that doesn't supply time with an arrow. On the contrary, exactly as he said before, that presupposes that time has an arrow. Because when you say that entropy is increasing you mean it is going from a lower state to a higher state. That presupposes that there is a direction of time rather than saying it is decreasing from the higher state down to the lower state. So he says the interesting question is not what about the thermodynamic arrow of time, the interesting question is why did things start out with such a low entropy? And that is right at the heart of the thermodynamic arguments for the beginning of the universe that I use in support of premise (2) of the Kalam cosmological argument; namely, the second law of thermodynamics shows that the universe began in an extraordinary low entropy condition. Why was there this low entropy condition in the past? Here Maudlin says,
One choice is that the universe is only finite in time and had an initial state, and then there’s the question: “Can you explain why the initial state was low?” which is a subpart of the question, “Can you explain an initial state at all?” It didn’t come out of anything, so what would it mean to explain it in the first place?
This is exactly the Kalam cosmological argument. In order for there to be an initial state of the universe as shown by this low entropy condition there needs to be a transcendent cause which brings the universe into being because something cannot just pop into existence from nothing, or as he says not out of anything. Now, he goes on to say,
The other possibility is that there was something before the big bang. If you imagine the big bang is the bubbling-off of this universe from some antecedent proto-universe or from chaotically inflating space-time, then there’s going to be the physics of that bubbling-off, and you would hope the physics of the bubbling-off might imply that the bubbles would be of a certain character.
This is where the famous Borde-Guth-Vilenkin theorem becomes so relevant because what that theorem shows is that there cannot be this past-eternal, chaotic inflationary bubbling off that Maudlin describes here. So the first alternative, I think, is the better choice – that the thermodynamic properties of the universe imply the absolute origin of the universe at a point in the finite past with a special initial low entropy condition.
KEVIN HARRIS: Edwin Tse says,
Given that we still need to explain the initial low-entropy state, why do we need the internal directedness of time? If time didn’t have a direction, wouldn’t specification of a low-entropy state be enough to give it an effective direction?
Talk about that question there a little bit.
DR. CRAIG: It is presupposing this very widespread view that it is thermodynamics that gives time its direction, its arrow. But there is no reason to call that low entropy state “initial” unless you already presuppose that time has a direction. Why not call it the final state? Even that would presuppose a direction in the other direction. So words like “final” and “initial” betray that you are already presupposing an arrow of time to begin with. So thermodynamics cannot furnish it.
KEVIN HARRIS: If you have an initial then you've moved from it so that you can look back.
DR. CRAIG: Right! Right! Which is a direction; that shows directionality.
KEVIN HARRIS: He answers,
If time didn’t have a direction, it seems to me that would make time into just another spatial dimension, and if all we’ve got all are spatial dimensions, then it seems to me nothing’s happening in the universe. I can imagine a four-dimensional spatial object, but nothing occurs in it. This is the way people often talk about the, quote, “block universe” as being fixed or rigid or unchanging or something like that, because they’re thinking of it like a four-dimensional spatial object. If you had that, then I don’t see how any initial condition put on it — or any boundary condition put on it; you can’t say “initial” anymore — could create time.
DR. CRAIG: Do you notice the way he corrects himself? You can tell this is a genuine interview. He says, “I don’t see how any initial condition” and then he corrects himself: “Any boundary condition . . . you can’t say ‘initial’ anymore.” Because you've just got this tenseless spatial block. This again betrays, or indicates, that his slip is showing, so to speak. His A-theoretical tensed-time slip is showing here, because on a tenseless theory of time change just means that as you go across one of the dimensions things look differently at different points on that dimension just as the scenery can be said to change from west to east. There isn't any change in the sense of becoming, but there would be difference between the universe at say 3 minutes after the Big Bang and 10 billion years after the Big Bang. But for Maudlin that's not enough to have real change. For real change, for things to be really happening in the universe, he seems to want to have the reality of tense and temporal becoming, which I cheer and applaud.
KEVIN HARRIS: He continues,
Suppose on one boundary there’s low entropy; from that I then explain everything. You might wonder: “But why that boundary? Why not go from the other boundary, where presumably things are at equilibrium?” The peculiar characteristics at this boundary are not low entropy — there’s high entropy there — but that the microstate is one of the very special ones that leads to a long period of decreasing entropy. Now it seems to me that it has the special microstate because it developed from a low-entropy initial state. But now I’m using “initial” and “final,” and I’m appealing to certain causal notions and productive notions to do the explanatory work. If you don’t have a direction of time to distinguish the initial from the final state and to underwrite these causal locutions, I’m not quite sure how the explanations are supposed to go.
DR. CRAIG: Very good. You've got to have the direction of time in order to even talk meaningfully about entropy increase or decrease, or initial and final.
KEVIN HARRIS: He says,
But all of this seems so — what can I say? It seems so remote from the physical world. We’re sitting here and time is going on, and we know what it means to say that time is going on. I don’t know what it means to say that time really doesn’t pass and it’s only in virtue of entropy increasing that it seems to.
DR. CRAIG: That clearly indicates, I think, his belief in the objectivity of tense and temporal becoming. He says, I don't even know what it means to say that time doesn't really pass and it's just an illusion produced in our minds by entropy increase. That seems to be, again, one of those telltale indications that Maudlin here wants to endorse a tensed theory of time. Here then he is going to take back with the right hand what he's just given with the left. Go ahead.
KEVIN HARRIS: Edwin Tse then asks:
You don’t sound like much of a fan of the block universe.
There’s a sense in which I believe a certain understanding of the block universe. I believe that the past is equally real as the present, which is equally real as the future.
DR. CRAIG: Let me just interrupt there. Here he does endorse the block universe and the ontological parity of all events in time whether past, present, or future. This is a view of time in which there is no temporal becoming; that everything just exists. And yet, as we've seen, so often already in this interview other things he says seem to betray that view but here he seems to want to affirm the block. But now read the next couple of sentences.
KEVIN HARRIS: He says,
Things that happened in the past were just as real. Pains in the past were pains, and in the future they’ll be real too, and there was one past and there will be one future. So if that’s all it means to believe in a block universe, fine.
DR. CRAIG: Notice here he gives a completely different characterization of the block universe. Now instead of present tense verbs he suddenly reverted to past tense and future tense verbs. He says things that happened in the past were just as real. Not that they are just as real. They were just as real. Pains in the past were pains, and in the future they will be real. They are not real, but they will be real. There was one past; there will be one future. And I agree with him. If that is all it means to believe in a block universe, fine. Every tensed theorist believes that. So I think here we see the kind of inner-contradiction or inner-incoherence in Maudlin's view. I don't think he is entirely conceptually clear on what tensed view of reality involves. He ought not to be affirming the ontological parity of all events past, present, and future. Rather he ought to affirm what he has said here in the latter part of the paragraph: things in the past were real, things in the future will be real, and that suffices.
KEVIN HARRIS: This is a complex paragraph here where he says,
People often say, “I’m forced into believing in a block universe because of relativity.” The block universe, again, is some kind of rigid structure. The totality of concrete physical reality is specifying that four-dimensional structure and what happens everywhere in it.
Then he gets into Newtonian mechanics. Can you expand on this a little bit?
DR. CRAIG: Yes. In Newtonian physics you can cast that physics in terms of a four-dimensional spacetime. What is distinctive about Newtonian spacetime is that it has an absolute foliation, that is to say slicing or division into moments of time that are present, past, or future absolutely relative to each other. There is a universal worldwide time in Newtonian physics which is the same for everybody in the universe. So if an event is present for one observer in the universe, it is present for anybody else at that time. There is this universal time. But then he says in relativity you don't have this kind of absolute slicing of spacetime. Rather different observers in spacetime will slice up the four dimensional block differently so that there wouldn't be any sort of absolute simultaneity. But he says, “I don’t see how that different geometrical character gets rid of time or gets rid of temporality.” It would just mean there isn't any absolute simultaneity. What Maudlin doesn't mention here but he could have is that Einstein's original special theory of relativity was not formulated in terms of spacetime. It was formulated in terms of ordinary three-dimensional objects enduring through time. So you don't need to have this geometrical interpretation in order to cast special relativity. I think he is quite right in saying that just having this different geometrical structure of spacetime doesn't do anything to show that temporal becoming or tense is illusory. It would just mean it is relative to reference frames. That is not my view but that would be consistent with Einstein's original 1905 paper which did think of temporal becoming and tense as real and objective but just relative to observers and reference frames. But I love what Maudlin says next. He says,
The idea that the block universe is static drives me crazy. What is it to say that something is static? It’s to say that as time goes on, it doesn’t change.
And you can't say that about the block universe because it is not in time, rather time is one of its internal structuring dimensions. So he really doesn't like this sort of tenseless block universe and yet he is not entirely consistent it seems to me in affirming the objectivity of tense and temporal becoming.
KEVIN HARRIS: He says,
Physics has discovered some really strange things about the world, but it has not discovered that change is an illusion.
DR. CRAIG: And notice again there in order to characterize change as illusory he is presupposing that change involves this idea of tense; that it is not enough just to have different descriptions of the universe at different times. In order for change to be real there has to be some kind of a process that goes from one to the other. He wants to affirm the reality of temporal becoming; that things turn into something else.
KEVIN HARRIS: He is then asked,
What does it mean for time to pass? Is that synonymous with “time has a direction,” or is there something in addition?
There’s something in addition. For time to pass means for events to be linearly ordered, by earlier and later.
DR. CRAIG: And here again he is taking back with the right hand what he gave with the left. This seems to be confused. Again to appeal to Adolf Grünbaum – Grünbaum argued for the anisotropy of time. He says that time is linearly ordered. It has an earlier-than direction and a later-than direction. And yet Grünbaum was a vociferous critic of the idea that time passes. So it is not correct for Maudlin to say for time to pass means for events to be linearly ordered by earlier and later. That is insufficient for the passage of time. What is needed in addition to anisotropy, as Grünbaum recognized, is the objectivity of temporal becoming. And that is what Grünbaum denied and rejected. Grünbaum affirmed the directionality of time, the anisotropy of time, but he rejected the idea of temporal becoming. I think that that is what is needed in addition to linear ordering in order for time to pass.
KEVIN HARRIS: He says,
The causal structure of the world depends on its temporal structure. The present state of the universe produces the successive states. To understand the later states, you look at the earlier states and not the other way around. Of course, the later states can give you all kinds of information about the earlier states, and, from the later states and the laws of physics, you can infer the earlier states. But you normally wouldn’t say that the later states explain the earlier states. The direction of causation is also the direction of explanation.
DR. CRAIG: And why is that? It is because of the objectivity of temporal becoming. Otherwise why not have retro-causation? You can infer the earlier states from the later states, so why not say it is retro-causal, backward causation? Because of the objectivity of temporal becoming. The later states result from the earlier states. The earlier states become, or turn into, the later states. So I think Maudlin is grasping quite right here that the order of explanation, the order of causation, is fundamental and it is going to be rooted in the objectivity of temporal becoming.
KEVIN HARRIS: He asked,
Am I accurate in getting from you that there’s a generation or production going on here — that there’s a machinery that sits grinding away, one moment giving rise to the next, giving rise to the next?
DR. CRAIG: Isn't that a clear question about the objectivity of temporal becoming? One moment giving rise to the next and then that giving rise to the next; a principle of generation or production. The interviewer is saying, Are you affirming this notion? And Maudlin replies,
Well, that’s certainly a deep part of the picture I have.
So he does seem to be wanting to affirm the objectivity of temporal becoming. I think he goes on to say that the machinery just is the laws of nature. But as he has already admitted the laws of nature allow you to infer either forward or backwards in time. There has got to be something more than the laws of nature to explain this process of one moment giving rise to the other. There needs to be temporal becoming. So as he says here, if I may jump ahead,
Other things are derivative from, produced by, explained by, derived from the laws operating.
That notion of deriving from, being produced by, and so forth, I think all presupposes the objectivity of temporal becoming.
KEVIN HARRIS: He says,
And there, the word “operating” has this temporal characteristic.
It is hard to get around the language.
DR. CRAIG: Right. I want to say more than that in that people like Grünbaum and other B-theorists or tenseless time theorists do affirm the reality of time. So they would say yes it is a temporal characteristic. But it is more than that. As the interviewer says there needs to be something in addition to just this sort of linear ordering. And that “in addition” is becoming. That is what the word “operating” has behind it as its characteristic.
KEVIN HARRIS: He is asked,
Why is yours a minority view? Because it seems to me, if you ask most people on the street what the laws of physics do, they would say, “It’s part of a machinery.”
DR. CRAIG: I think that the question is misconceived because, as I say, the laws of physics itself don't explain the difference between past and future. You need temporal becoming to explain why the later states derive from or are produced by the earlier states. But Maudlin says,
I take “time doesn’t pass” or “the passage of time is an illusion” to be a pretty bizarre view.
Here he affirms unequivocally the idea of the passage of time which I take to be an affirmation of temporal becoming. And he actually says the view of physicists and some philosophers that temporal becoming is illusory and that time doesn't really pass in that sense he thinks it is bizarre. And I agree with him.
KEVIN HARRIS: The final question that he is asked, Edwin Tse says,
What does this all have to say about whether time is fundamental or emergent?
You might want to talk about that question a little bit.
DR. CRAIG: This is a debate among philosophers of time as to whether time is part of the most fundamental description of the way reality is, or on the most fundamental level is the universe really timeless and then time is a sort of emergent property at a higher level of description of the way the universe is. To try to illustrate this, one might say that the wetness of water is not a fundamental property of water. H2O, the hydrogen and oxygen atoms combined, those describe the fundamental properties of water, but at a higher level of description this emergent property appears that water is wet. But the wetness isn't a property of that fundamental level of description of hydrogen and oxygen atoms. Those aren't wet. That would be analogous to the way some theorists think of time. They want to say reality is not at its most fundamental level temporal; that time is just an emergent reality or a higher level of description. And I love Maudlin's response. He is so much like the little boy who says the emperor is wearing no clothes. Why is the emperor naked? He says,
I’ve never been able to quite understand what the emergence of time, in its deeper sense, is supposed to be.
He doesn't even understand what it means. He says,
How do we understand — and is the emergence a temporal emergence? It’s like, in a certain phase of the universe, there was no time; and then in other phases, there is time, where it seems as though time emerges temporally out of non-time, which then seems incoherent.
He is absolutely right. It is incoherent to say that in its earliest initial phases the universe was timeless and then later on time emerged because that presupposes time. You can't have a temporal emergence of time. So when emergentists talk about the emergence of time they are not talking about a chronological emergence. They are talking about different levels of description. Rather the universe at its most fundamental level of description doesn't include time but then at a higher level of description the property of time is part of the description. That in no way implies that time is therefore illusory any more than the wetness of water is an illusion. I tend to agree with Maudlin though that there is no reason to think of time as an emergent property especially if you think of time in the way I do as a metaphysical reality that isn't dependent upon physics or its laws. Maudlin says, to close out the interview,
And for me, again, the notion of temporality or of time seems like a very good place to think I’ve hit a fundamental feature of the universe that is not explicable in terms of anything else.
Time is at the bedrock of our understanding of reality. And for Maudlin, time, as we've seen, I think, involves the objectivity of tense and temporal becoming. What that implies is that if there was an initial state of the universe then that initial state just popped into existence from nothing unless you have a transcendent personal creator of the universe to bring it into being.