God is not a Good Theory (Sean Carroll)

It is very

good

to be here, as you can see from my title, I am going to address the question of the role that the idea of ​​God should play in the explanation of the universe that we see from the point of view of a scientist, a physicist or a cosmologist. It is not the point of view of a professional theologian or philosopher. I think the point of view of a physicist or scientist is relevant to this question. It is not the only possible point of view one can have. There are aspects of the idea of ​​God that cannot be reduced to the roles that a simple scientific

theory

plays, but there are also aspects of the idea of ​​God that do play the roles of a scientific

theory

and those aspects can be judged by the same criteria that we use to judge the theories in the original. program if you've seen he removed the word

good

from my title so he just said God is not a theory but that's the opposite of what I'm trying to say here so just so you know my point I'm saying That God is a theory, the idea of ​​God to the extent that almost all believers use the idea of ​​God has aspects that can be judged in a way precisely analogous to the way we judge an ordinary scientific theory.

Now I'm very well. aware that there is a train of thought that says the opposite of that which says that the idea of ​​God is something that separates a different type of idea from the ideas that we use when we have theories of physics, then you know that God is not reproducible or something So. I just want to solve that particular definitional problem by raising the idea that theory is a very, very broad thing. I don't want to pick a very specific definition of a philosophy of science for me, a theory is just an idea about the universe that can be true or false and we should try to figure out how to judge whether this particular idea is true or false, so that one of the problems with God as a theory is that it is not a very precisely specified theory that One of my points is that, although we sometimes try to have God play the role of a physical theory by making predictions and explaining things while preserving some explanatory role, I'm going to argue that it doesn't do a very good job. now again I will do it, although I am not a trained theologian.

I certainly know that we have different conceptions of God. In fact, this is what I would say is one of the check marks against God, since a very good theory is that if you try Say well, here's why I don't believe in God, someone else will say, oh, I just don't. you understand what God is. God is completely different from that and I admit that I will at least try to explain what versions of God I am talking about. I can't guarantee that they are your favorite versions of God, so we can choose three that are not an exclusive list of passive active and emergent conceptions of God and what I mean by this under passive is the type of roles that are given to God . going back to some of the ancient Greeks going back at least to Aristotle a kind of philosophical role for God as something that helps explain helps sustain the universe and the unmoved mover a first cause a necessary being various philosophical notions that are not necessarily empirical in the The way scientific theories are, this type of God is something that we need in this conception to make sense of the universe, not something that necessarily goes around poking around in the universe and intervening in it and changing the physical laws, the active conception.

God is a more personal idea, often people define God as a type of person, just as often they say that God is not a person, but there is this conception of God as someone who cares about life here in the world. earth, cares about human beings and cares about both. in the sense that you know he wants us to succeed, but he also sometimes judges us and sometimes a little harshly. It depends on how far you want to go, but God will give you moral guidance and establish an afterlife for you. being ordained once you die, etc., there are various uses that this more active type of God has to perform and finally there is what I like to call an emergent idea of ​​God, which is that God is not a fundamental category , but God as a way of talking about aspects of the universe that you could also choose to talk about in different ways God is the laws of nature God is the order of the cosmos God is the universe itself where God is love where God is our feeling of everything in transcendence As we approach the universe and these different conceptions of God have different justifications, one can try to justify the passive notion of God that lies at the bottom in purely logical terms by simply thinking about how the universe could be the most active of God.

It will essentially be an empirical argument that the best way to explain the universe we see is to imagine that God is doing these things in an active sense, whereas the emergent idea of ​​God is a more rhetorical move and I don't mean that in a sense. asset. Any derogatory form is a way of talking about the universe we see, so I'm not really going to talk about this third category. My personal belief for those of you who are fascinated by her is that I don't see the need to talk. about the universe in that vocabulary, but you know, if you want, I won't stop you.

What interests me most for the purposes of this talk is how much more the conceptions of God that introduced God are a separate metaphysical category that we have something to do with and I'll start with these more philosophical metaphysical arguments for God. I think as a scientist the second category is more relevant, but I have to eliminate this one before we can. move on to the second, so what does it mean and what is the role of God as an unmoved mover as an Aristotelian first cause? God is a necessary being very often if you ask theologians, do you know how the universe would be different if God did not exist, they will say that I cannot imagine a universe in which God does not exist, therefore they cannot answer me that question, as a scientist, there is a big problem from the beginning with this type of reasoning, which is that the entire strategy is based on a priori metaphysics, that is, you know a lot about armchair philosophizing, you know, in the best sense of the word, to sit and think about all the possible ways the world can be and conclude that those ways must somehow involve the idea of ​​God, you never do, there is no step in that process where you actually go out and look what the universe is really like, you don't need to do it this way because you can just logically argue that God must be part of the universe.

I firmly believe that this type of reasoning has never taught us anything true and interesting about the real world, that does not mean that thinking in an armchair without going out to look at the world is not useful in any way. mathematical logic is extremely useful other branches of philosophy and formal research are not empirical in nature they do not involve going out and looking at the real world they reason in an a priori sense but they also do not reveal interesting truths about the real world mathematics reveals consequences of the axioms you It says I have a certain axiomatic structure and I deduced theorems based on that, it doesn't tell you which axioms are possibly true if you really want to discover our universe, does it imply any notion of God? a real fact about the specific universe we live in and I personally don't think this kind of reasoning is going to get us there, but let me take it seriously for a moment and tell you my feelings as a scientist on this, how could we refute the claim of that God is a necessary being, for example, and I must also admit that I am happily combining all sorts of ultimately different a priori metaphysical arguments, first because the prime mover is necessary, all of these are subtly? different in ways that I'm going to completely ignore, sorry, they taste similar and I'm going to treat them similarly, so if you believed God was a necessary being you literally couldn't imagine a universe. in which God did not play a major role in order to logically disprove that belief, all I need to do is invent a universe in which God does not exist, you know, if you say that all swans are white as a logical fact, all that What we have to do is show you a Black Swan to show that your logical argument cannot be correct, so all we have to do is invent a universe in which God plays no role and that would enhance your imagination enough to that you can imagine.

Universes where God was not important I claim that it is not difficult to invent universes Possible universes The hypothetical universe is not necessarily ours, but autonomous, consistent, coherent universes in which God plays no special role, no role at all, so here there is the universe. Sorry for the mathematics, this universe is a three-dimensional space that evolves in time and in that space there is a particle that is the entire universe, this particle moves according to Newton's laws of motion under the influence of some potential energy , so here is space, there is time. There is our particle moving, it has an equation of motion and this continues forever in the childhood past or the infinite far future.

I claim that this is a logically conceivable universe, but you can't help but imagine that this is the universe, it clearly isn't. our universe I'm not trying to claim that there is some complicated transformation that makes our real world look like this, but this could be a universe and there is no God in this universe, there is just a moving particle if you want a slightly more realistic example here. It's a universal, I think you might actually be right. Replacement instead of three-dimensional space. I have a space of states which is a Hilbert space, that is, a quantum mechanical space of possible states, the space of wave functions, if you like, there is also time. evolution then the state is an element of that Hilbert space and it evolves over time if you want to know how it evolves while solving this equation The Schrodinger equation where this capital H is an operator called a Hamiltonian that basically tells you how the Bowls state changes with time, so this universe is mathematically isomorphic to a trajectory in a Hilbert space, according to Schrodinger's equation, it goes forever from the infinite step to the infinite far future, it is autonomous, there is nothing outside this universe that hold it. sustaining it keeping it going causing it to exist or allowing it to persist is just that mathematical structure and that's it, I actually liked what I said, I think this is a plausible mathematical structure for the real world we live in, clearly there are some details that need to be filled out I need to know what the actual Hamiltonian of the world is, which I don't claim to know, but this is a plausible framework for reality and just to give you a final idea of ​​what types of universes I'm thinking of.

Here is a world, a universe, it is a point, it is actually bigger than a point because it is difficult to show you a point, so this is a circle, but imagine a mathematical structure that is isomorphic to a single point. I claim that it is a once possible universe. Again, it's not our universe in any interesting way, but it is a conceivable universe and once again, God plays no role, so what am I trying to get at here? What I'm trying to get at is that if you sat down again a priori. and I tried to think of all the possible ways that existence could manifest, we know that, at least to some extent, there are mathematical ways of talking about existence, talking about the real world.

I can easily imagine self-contained and consistent mathematical structures in which the notion of God or necessary beings or first cause plays no role now. You know, this is not a brilliant new idea. People who do believe in necessary beings and such have an answer to this. They will say sure you can. Imagine that, but in reality they are not legitimate possibilities of how the world can please you and that is because there is no fundamental explanation, there is no reason why the world is the way it is, that God's role is to substantiate why this is the case. world instead or in fact why this world at all why a world at all then the answer to my examples would be safe, you can write them down mathematically but you haven't explained why that would be the universe and my answer to those arguments is then , who can say? that I'm supposed to explain why a universe exists, maybe you'd prefer there to be an explanation of why this universe instead of that universe, but you can't logically prove that there must be some explanation, the universe might just be that's the disagreement fundamental between people who believe in a metaphysical notion of God and more empirically minded scientists, so let me elaborate a little.

Just because we have a universe, is it necessarily true that there is some explanation, reason or cause? I think the reason you're tempted to think that is because in our current universe you associate causes with events. Things happens. I can explain to you why that happened. Here, the reason now there are two things to notice about that is that there are very often multiple different sounding reasons can be given for a single event, why this football team lost their game well.because the goalkeeper let that goal in or because they were not well prepared or because space-time is four-dimensional, I mean.

There are many possible reasons you could give, what counts as a reason depends on the framework in which you are talking. Reasons do not exist once and for all in a unique way, by themselves, they appear within contexts and the context in which the entire universe appears is different, whatever it is. could then be all the contexts in which things appear within the universe even if it were true when I don't think it is true but even if it were true that everything within the universe can be associated with a reason or a cause that does not mean that they are the same. thing applies to the universe itself, it may or may not, and so the second point is that you may want to invent a principle, you may want to invent a way of thinking, the principle of sufficient reason or something, that simply requires that things have explanations that nothing that happens happens without a reason but my answer to that would be why why it is necessary that everything has a reason and you could give an argument you say well when I look at the universe everything that happens has a why why but the point is that now you are taking your metaphysical argument and turning it into an empirical one why it is necessary for things to have reasons or explanations well I see that things have reasons or explanations but that doesn't mean you can just draw the conclusion that everything that happens must happen for a reason.

The example I like to use is conservation of energy because conservation of energy is a thing. As you look around you you see many different things happening, many different processes, dynamic events in The world you are going to look at every time I can associate a number, the energy that is constant in time, does not change in the process of this dynamic event, so I invent a law of nature of conservation of energy, but the point is that logic is not. I see that energy is conserved, therefore energy is conserved. The logic is that I see that energy is conserved, therefore I make a hypothesis.

I imagine that energy is actually conserved and then I go out and test that hypothesis. It is empirical. I'm looking for a logical foundation. based on some broader theory and I actually do tests. In fact, there is experimental evidence of energy conservation. I could also be wrong if you see that everything in the universe happens for a reason that I don't think is true, but even if you saw that at best you could say so, therefore I hypothesize that maybe everything happens for a reason, maybe therefore the universe has a cause or a reason, but that's not just a metaphysical demand, it's an idea that you should go out and try. is again an empirical statement and should be evaluated accordingly, it is just one more example.

There is something called the Kalam cosmological argument which begins by saying that everything that has a beginning has a cause and therefore says that the universe has a beginning and then says the universe has a beginning therefore the universe must be caused but the answer This is maybe not. I don't even need to say that no, it is not true that everything that has a beginning has a cause. All I need to be able to say is maybe it exists. are things that happen without causes, then it becomes an empirical statement that I need to go out and judge just as I judge any other scientific theory, like conservation of energy, so the conclusion of this type of reasoning is that we need to think about God as an empirically testable hypothesis, not as something completely incorrect, even supposed metaphysical arguments that God is necessary ultimately boil down to contingent empirical claims, so what we should ask is whether to include God in our Ontology makes God play a role in our conception. of how the world works give us the best possible theory on conventional scientific bases.

Now it is true that we do not understand what those conventional scientific bases are with perfect clarity. The idea of ​​what is the best possible explanation for something, even within science, is a bone of contention. But I'm not going to go into details about that. I think we all know it when we see it. When it comes to what constitutes a good scientific theory, we are looking for something that is a simple, coherent theory that explains the largest amount of data and when it comes down to it, it is not difficult to imagine aspects of the observed world, but you could say that the best possible explanation for this observed phenomenon is the existence of God historically, which has certainly been true, so movement is one of them, remember.

One of Aristotle's conceptions of God is an unmoved mover and this is the one that when I was a student at my Catholic University, taking all those religion courses made the least sense to me and it took me years later until I finally figured out why I didn't have sense. I understand why you needed an explanation of why things move and the answer was that in an Aristotelian metaphysics you are basing what happens on Aristotelian physics in which motion is something that needs to be explained directly in Aristotelian physics in order to be able to do it.

For something to move, you have to push it and keep pushing it and we see things moving everywhere, so there must be something doing a definite push in some sense, but then comes what we now know as conservation of Seine momentum. and Newton and Galileo point out that, left to their own devices, things don't need to be constantly held or pushed to keep moving, things will keep moving, so the idea that things are moving is not something we needs to be explained, it is simply something that is a law of physics it is an aspect of the world I think you know the change in theological thinking that somehow implicitly followed the invention of Newtonian mechanics is something interesting and underdeveloped in that To think, of course, there is life and I think that for many people now and in ancient times the reason we are tempted by supernatural explanations is because living things look very different from non-living things living things are alive and conscious and respond in interesting ways seems to be the simplest explanation you know when something dies when it goes from being a living object, a living organism, to being a corpse, it seems that something changed, something left it, something is now absent, there was some type of spiritual energy, some life force and I think it is a very obvious motivation in a primitive society to think that there is something beyond the merely physical, but today we think that there is nothing about life or death that does not can be explained in principle only by chemistry and only by biology, of course, there is a design, not only the existence of living creatures but also of the wonderful diversity of all the different species of creatures that we have here on earth, there is a British man named Charles Darwin who explained that in terms of natural selection and today we still have some unanswered questions, there is the question of consciousness, what makes a person have a feeling of what it is like to be themselves to reflect and think into things that I'm hopeful neuroscience is addressing and continues to improve in understanding what consciousness really is.

I am not a professional neuroscientist. I'm not going to talk about it. That, but given the empirical success of science and giving naturalistic explanations for the characteristics of the universe, I don't see any obstacles to that happening. In the case of consciousness, finally there is also the origin of the universe itself and here I have some experience in what naturalistic science means. The modes of explanation have to say about the origin of the universe. It is a traditional role that God must play. If you take the Bible, it's there at the beginning. God is creating the entire universe.

So this is what we know from the modern perspective about the origin of the universe. Origin of the universe 13.7 billion years ago, the universe was in a hot, dense and rapidly expanding state, which we call the Big Bang. Much of the credit for this idea goes to George Lameta, a Catholic priest. After La Mettrie helped invent the idea of ​​the Big Bang, the Pope attempted to use him and try to match the scientific theory of the Big Bang with a theological vision of that God created the universe from nothing and Lumetri very wisely advised him not to do that, but nevertheless the Big Bang left.

When we ask questions about the origin of the universe, the Big Bang is not necessarily the beginning of the universe, we often talk as if it were, but what we are really doing when we talk about the Big Bang as if it were the beginning is that we. We are using a theory to draw a conclusion when we have no right to believe what that theory tells us. That theory, of course, is classical general relativity. Einstein's theory of space, time and gravity is extrapolated in classical general relativity to the Big Bang and is maintained. Going back, you reach a singularity at a time when the spacetime curvature, expansion rate, and energy density are infinitely large, so in classical general relativity you would say it is a spacetime boundary. , that is, a point beyond which you cannot pass.

However, we no longer have any reason to think that classical general relativity is an appropriate and correct description of what is happening near the Big Bang. We shouldn't think of Djenne from the Big Bang as the beginning of the universe. We should think of it as the end of our understanding of what is happening, we need to do a better job, at least a theory of quantum gravity, before we can draw conclusions about what happened at that time. Now it is better to simply say that we don't know what we can. Of course, can we know if it is possible to imagine theories of the universe that explain the beginning of the universe or should we keep that idea separate by giving God a chance to sneak in and play a role?

I don't know what the correct theory is about the origin of the universe, but I have no shortage of plausible theories, so let me give you a few of them. One is that the Big Bang really is the beginning of the creation of the universe in some sense. out of nowhere Stephen Hawking has obviously promoted this idea very famously for a long time, but it's not the only one on the market: there is the cyclical universe, the universe in which the Big Bang is just a phase that the universe goes through , which expands and collapses again. and it bounces an infinite number of times there is eternal inflation, we are Joe, we already talked about inflationary cosmology, the idea that from a small portion of space a negative pressure fluid can force the universe to accelerate an enormous amount and grow a lot in volume .

I discover that that can happen forever and that you can go from one small universe to many many small subuniverses in the neck and happen again an infinite number of times. There's also my favorite idea, which is that these kinds of things happen but they happen in both directions. of time, so there is a point in the universe that is a kind of middle and to the right and left of that the universe grows and gets bigger and creates many small descendant universes. Any of these models is, as I said, autonomous. It tells you the entire history of the universe, there is no external influence that is giving the universe into existence.

I am not advocating that any of these models are correct. I'm simply pointing out that there is absolutely no reason to fall on our swords and let's say we need help explaining the origin of the universe outside of conventional naturalistic explanations. We don't need God to explain the origin of the universe. However, it is still possible that God is a better explanation than any of the purely physical naturalistic ones I have proposed. was talking, so we should judge God by the same standards that we judge all other theories by. In my personal opinion, the best argument based on empirical data for the existence of God comes from fine-tuning the physical parameters in our universe.

It seems to be true that if you look around in the universe, we characterize what is happening with various numbers, the energy density on average, the expansion rate, physical parameters like electron mass, etc., it seems to be the case that if you changed many of these numbers by an appreciable amount, things would be very, very different. I said it weakly enough that it's almost certain that if you changed the mass to give the electron a substantial amount, things would be very, very different. It is plausible that for many of these numbers, if changed by an appreciable amount, life would not exist.

That's a fact. It seems probable or at least possible that the values ​​adopted by the physical and cosmological parameters that we observe around us allow existence. of life and not many would, furthermore, it seems that some of these physical parameters are not natural, that is, if you took them out of a bag, the mass of the energy density of the electrons, the expansion rate of the empty space of the universe, you would get very, very different numbers than what we actually observe, so you can see where the argument is going. It requires certain parameters veryspecifics, the argument says that there are parameters in the universe for life to exist.

These parameters do not appear to be generic, they do not appear to be ones that would easily be found. obtain by simply choosing random numbers for the universe and yet they are right there where you need them for life to exist why were we so lucky to find ourselves in a universe that seems unnatural but in a way that allows the universe to be? hospitable to the existence of life is a very natural and sensible place to ask whether or not there was some design at work, whether or not God helped the universe a little in choosing the appropriate parameters to allow the existence of life, the best example in my mind it's the cosmological constant the density of empty space the energy of the vacuum this is something that we think is not zero, you know, when I was your age we thought this was zero when I was in graduate school, but in 1998 We discovered that the universe is accelerating in a way that is exactly compatible with a small but non-zero energy density in empty space.

The reason this is interesting is because you can sit back and wonder if I didn't look at the universe if I just estimated it based on what I know about particle physics and cosmology, what do I suppose the value of the vacuum energy should be? My guess is greater than the observed value by a factor of 10 to the power of 120, that is, if it is true that we have a non-zero but small vacuum energy, we don't just pick it out of a hat at random, we think we know what it would be. the natural value if we were to pick it at random out of a hat, is very, very, very different from the value that we actually observe, so our notion of picking it at random out of a hat is either very, very wrong or is there some dynamic explanation for why The value of vacuum energy is so small, so what kinds of possibilities could help explain this apparent fine-tuning of nature's parameters?

Well, one is that we were just lucky. It is never entirely clear to me that asking this question is a sensible thing to do. Aren't we lucky that the laws of nature allow us to be here wondering how lucky we are? I'm not sure it's a sensible question because if the laws of nature didn't allow us to be here, we wouldn't be asking the question. Everyone who asks the question is lucky enough to live in a universe that allows them to exist. However, I don't find it entirely plausible or at least. At least you know, as a working scientist, it seems like a cop-out to say: well, we just got lucky, the laws of physics allow us to be here, it's not that nice, let's move on.

I suspect that this apparent adjustment of vacuum energy and other constants of nature or Clues, are telling us something, there is something we don't understand about the universe, we should try to do better, so I'm going to leave aside this possibility, another possibility is that the parameters are not close. No matter how sharp we think when it comes to explaining the existence of life, perhaps for very different values ​​of the parameters there will be other types of life, it is extremely presumptuous. I think we understand perfectly well when life might exist, maybe life is pretty generic and then the last two more substantive possibilities are maybe what we're seeing as a selection effect maybe the parameters of our nature are very different from one place to another. to another perhaps most places are completely inhospitable to the existence of life but of course there is environmental selection we are only going to find ourselves in those regions of the universe that are hospitable to us, therefore we observe these finely tuned parameters or someone made it that way God intervened made the parameters because God wanted to make a universe where we could exist.

What would be the point of the universe without us after all? So let me talk a little about this second possibility: the idea that life is much more generic than we think and that parameters don't need to be. that are finely tuned to obtain something like life if we were really serious about claiming that the parameters of the universe are clearly fine-tuned in such a way as to allow the existence of life, this is the kind of argument we would have to do so we would have to say consider all the possible physical theories consider all the possible cosmological manifestations of those laws of physics consider all the possible ways that life and/or consciousness or something like that could exist within those universes and then calculate the fraction of those universes compared Regarding the number total of possible universes, now no one does this.

Religious people who would argue that fine tuning is for God. Don't do this. Physicists and cosmologists who want to argue that the multiverse is necessary to explain things do not do so. Do this, no one does this because it is wildly impractical. Our knowledge of all the possible laws of physics is nowhere near allowing us to make this argument and the scientists are as guilty of this as any of the theologians who want to use this as evidence. For the distance from God there are some arguments that say that if the mass of the neutron was smaller than the mass of the proton, life could not exist.

Personally, I have almost no faith that we would understand what the universe would be like if the parameters of nature were very, very different, so I'm open-minded about it, but it's clearly a very difficult problem. I just want to admit that it is as much a problem for scientists as it is for religious believers. Okay, let's move on to the multiverse. the multiverse versus God, let's see if we can really adduce evidence for or against the existence of God from the fact that the parameters are nominally adjusted and here just to make things seem like science II we use the basic theorem of the theorem of Bayes is the way we take our expectations about what should be true and update them based on the evidence we get about the universe, so what we mean is that we have some observations, some data D and we have a set of possible theories that could be true T sub I and then we define different ways of associating probabilities with these theories being true, so that P of X given Y is the probability that Very crucially, we have the prior probability for a given theory. we have to say that not all theories are created equal, we give a larger prior probability to theories that seem more powerful, simpler, more elegant, that require a lot of special arguments and finally adjustments, they are given smaller prior probabilities , That's the way. that science works and then Bayes' theorem tells us that once we observe our data, the probability that we assign to our theory being the correct explanation for that data comes from taking the prior probability that the theory was true before obtaining the data and then multiply it by the probability of the data being true in that theory, then if the theory is true, what is the probability of the data happening?

That is the probability that the theory is true given that we observe that data and this is just a normalizing factor at the bottom. Basically all of this tells you that what you need to keep in mind is that when we judge our theories we need to calculate two numbers, we need to calculate the probability that the theory was correct before we even look at the universe and have to update that probability by now saying that We have observed the universe, how does that probability change? So let's apply this notion to both God and the multiverse, starting with the multiverse, the idea that in many different regions of space the laws of physics are very different.

We are only in the hospitable regions of space, so most people agree that the probability that life can exist if the multiverse is true is substantial, it is close to 1 if a multiverse really exists, which is very , very big and has all kinds of things. So somewhere there life may exist and anyone who talks about this universe will exist in those little sub-places where life exists, that's more or less uncontroversial among people who are both pro and anti-multiverse. The controversy is over what prior probability should be given to this theory. This is our judgment on how good a theory the multiverse is.

First of all, should we penalize the idea of ​​the multiverse because it is not simple? It is ontologically extravagant. of these things that you will never observe, not even in principle, just to explain some parameters in our small portion of the observable universe, so forcefully put it by Richard Swinburne, a theologian who says that postulating a trillion trillion other universes, a trillion trillion It's hilariously small in comparison. to the actual number of universes that we generally postulate, but we postulate trillions of trillions of other universes instead of one God to explain the order of our universe, seems the height of irrationality, so high if its rationality is a fanciful way of saying that the Prior probability should be very, very small Swinburne is saying look at this, you're just postulating many, many invisible entities to explain one or two features of yourself or the observable world, that's not good science, that's what he's saying, of course, The problem with this is that one does not postulate billions upon billions of universes that is not the way the multiverse works this is the crucial point the multiverse is not a theory the multiverse is not something that people sit down with and say hey , you know, what would be cool?

If it were like a billion universes or a billion or ten for the five hundred different universes, wouldn't that be interesting? This is not how the idea arose, but rather the multiverse is a consequence of other theories, so it is not that you postulate a billion different universes. that you postulate a small set of possible laws of physics and these laws of physics predict the existence of many, many different universes in the early 1980s Vilenkin and Lynda and others invented what we call eternal inflation which if you believe that inflation It is possible, inflation is a very well-founded physical scenario, we do not know if it is true or not, but it is a very plausible scenario to explain the observed homogeneity and isotropy of the universe.

What Valentina Linda showed is that if you believe that, then in a wide range of possible inflationary models, inflation never ends, it ends in some region of the universe, but in other places it continues and keeps creating new regions of the universe, it is not something that you must include in a very generic way, arises from your attempt to explain the observed modernity of our universe. In the late 1990s, string theorists realized that as you go from 10 or 11 dimensions of spacetime to string theory that posits up to the 4 we know and love, you can do it, but if you can do it one way, you can do it. 10 to 500 different ways and all these different ways of compacting the hidden dimensions of space give us different laws of low energy physics, this is called the landscape of string theory, all kinds of different possible parameters that you can imagine getting a huge huge number of them, so string theory says that the laws of physics could be very different from place to place.

Inflation says that it is easy to physically create regions that actually have those laws. Now both schemes are optional, we don't know if they are absolutely. true, they're not that established, but the point is that the number of things you're postulating isn't trillions of trillions, it's more like two or three, you're not arguing against the statistical mechanics of the atmosphere in this room. geez base, you need a lot of molecules in this room to explain this, you don't count the theories, you don't count against the theories because of a number of elements in a certain set that the theory invokes, you don't say that the integers are ontologically extravagant because there are an infinite number of them it is a simple pattern that generates all integers there are only a small number of types of air molecules in this room there are only a small number of physical principles underlying the multiverse the way to judge the probability of the multiverse scenario is judging the plausibility of inflation and string theory or some different ways of getting the same kind of things, but once you have these dynamical laws you get many, many different regions of the universe that you don't get. postulating them separately doesn't count as an attack on the theory, so I would conclude, so I don't know what the answer is here, that what we're trying to get here is what is P of the multiverse, what is the a priori AA. probability you should give about the possibility of a multiverse existing.

I wouldn't say it's necessarily close to one, but I wouldn't say it's 1 out of 10 to the power of 500 either. You don't decrease the probability every time you add a new universe. It decreases the probability of the conceptual complication of your theory every time you add a new idea and, by that measure, the multiverse might not have an order close to probability 1, but it is not extremely unlikely either, it is something verysensible to consider, so now let us turn to God. What is the prior probability of God and the probability that God is true, given the data?

So later I will talk about prior probability. Let's talk about the probability that God is the best explanation for the data we see, given that God exists. Do we expect to see this type of universe? So I have no problem believing that if God exists, then life should exist. I'm willing to grant God theorists that the kinds of gods we're talking about here are the ones who would do it. It is possible that we exist. I don't think it's a difficulty. It's the other data, the data other than the fact that life exists, that gets God into trouble as a hypothesis, and this is a very, very difficult thing to do correctly.

What we are trying to do here is ask if we knew nothing about the real universe but had a theory that says that there is something called God that created the universe that cares about us humans, that has a large or infinite scope. amount of power, etc., what do we expect the universe to be like? It's very difficult to do this because God is a little big, frankly, God doesn't make unambiguous predictions and we know what the universe looks like, so we tend to say well, God would do it. This is what we see the universe looking like, but that's not entirely fair, we need to answer as honestly as possible what we would expect the universe to look like if god were responsible for it, so my favorite example of this is low entropy. of the early universe this was the topic of the latest Oxford mini course on philosophy and cosmology the arrow of time in the modern conception of the arrow of time we understand that the microscopic laws of physics are perfectly reversible the same thing that goes forward and backward in the time, but the reason macroscopic physics has such pronounced directionality is that there is a boundary condition in the early universe: it has a much lower entropy than it would have if you picked the universe again.

At random, by chance, a lower entropy by a factor of about 10 to the power of minus 10 to the power of 120, so this is not a typo, so the cosmological constant is tuned one part in ten to the power of one hundred and twenty, this is one part in 10 to 10 to one hundred and twenty, so there is a huge Lemoore adjustment involved to explain the low entropy of the early universe and, fundamentally, the cosmos will come from vacuum energy, you can argue that if it were larger by a couple of orders of magnitude in which life would not exist.

I'm not sure I bought that argument, but you could argue for entropy. However, that argument fails completely. It makes no sense that the entropy of the early universe had to be so low. just for life to exist could be enormously higher, it could be almost order one compared to this and we would still be fine, so if you were really trying to be consistent, I would say that the probability that the entropy of the early universe could be as low given that God created the universe so that we would be here is of the order of 10 to the power of minus 10 to the power of 120, so it is a lot of evidence against God if we didn't know what the universe was really like and just said God created the universe so that we were here.

We would predict an early universe with enormously higher entropy. Another way to say this is here is Hubble's ultra-deep field. This is what you get when you point your camera at the sky and just take a picture if your camera is attached to the Hubble Space Telescope and you'll see all these little specks, each of which is a galaxy comparable in size to our Milky Way, so that each of these galaxies has billions of stars on the order of one hundred billion. stars there are a hundred billion such galaxies in the universe none of them are necessary for us to exist here on earth if you are simply going to create the universe and solve problems fitting it enough for life to exist there is no reason to create any of these galaxies, all the matter, all the degrees of freedom in those galaxies would have to be in thermal equilibrium.

If you're going to claim that your explanation for fine tuning is that God made it that way for life to exist, you strongly predict that this should be a blank or at least just a chaotic mess, it shouldn't have all these other galaxies in there and be That many religious believers would look at a picture like this and say, oh my goodness, the glory and stupendous news of God's creation. I look at a picture like this and say how the hell can you think the reason for this is to allow us to be here. We are very small compared to a very large universe, so there is a course of responses to these types of arguments.

I've thought about it, they say, well, maybe you can't create us, maybe you can't form our solar system without forming all those other galaxies, etc., this is simply false, everything we know about physics tells us that none of those other galaxies is You need to explain what we have here in our neighborhood, so you say, well, maybe the reason you get all these other galaxies with this really lower entropy than you ever needed is because God is kind of procedurally thrifty. . God not only does, I mean, remembers. He is God we are talking about. God would have no problem making just the Milky Way if that's what God chose to do, but you could say, well, God wants to play by his own rules, so God plays by the laws of physics, so God makes use of them. some physical mechanism for the creation of the universe that, as a byproduct of creating conditions that allow us to exist, also creates a hundred billion other galaxies, so it's plausible, but you see what's happening, you see that in trying to explain this characteristic that we would not have predicted we are pushed to create an essentially physical naturalistic scientific explanation, we are eliminating all the usefulness of God, we are saying that the reason the universe looks that way is because there is some physical mechanism that makes it look that way and that's what God used, but That's a story I can tell without invoking God at all.

There is a physical mechanism that made the universe look like this and then I can stop so that the advantage you might have had by invoking God in the first place is gone. This type of argument. that a priori the entropy of the early universe would not have been expected to be so low if God were the explanation, is the same type of argument that has been used to argue against God for millennia, now its probability that if God really existed, the world would exist. It doesn't seem like we're talking about that. This is the problem of evil.

If God existed, we would not expect there to be evil. This is the problem with random suffering, even if you argue that evil is necessary for free will and being human. election and so on there is no reason for you to know that we have natural disasters that kill innocent children or something like that. God could prevent that from happening. It's not what you would expect. Our priority. My favorite is the instructions problem if I didn't know what. what the universe was like, but I thought the universe was designed and created by an impotent God who wanted us to do well.

The first prediction I would make would be that God would explain to us very clearly as the author of a textbook that he has read. your amazon.com reviews. I would expect God's textbook to be perfectly clear. It may not be easy to follow the instructions, but I would know what the instructions were. It would have been very easy for God in some Holy Scripture to give us some clues to say that you know that matter is made of atoms, that the universe is billions of years old. People of different races, sexes, genders, and sexual orientations should be treated equally.

Governments should draw their power from government consent. A lot of things God could have. he told us and chose not to do it. That's a prediction he would have made otherwise. Finally I like to say that this is one way. I like to say it. Imagine his theologian in a world where there was no evil or random suffering and where God had given perfectly. clear instructions there were sacred scriptures that said know how to be kind to one another blah, blah, blah, blah, if I were that theologian, I would take the absence of injustice in the world as evidence against the existence of God.

I don't think so. I think so. would be fine, this is what I would expect God to do, he created a just society for us, if he didn't count the absence of injustice as evidence against the existence of God, then you should count the presence of injustice as evidence against the existence of God . God, there are a couple of ways to salvage the idea that God would have created data like this: just erase God's fingerprints everywhere to say you know what God really likes to do, act like God doesn't exist. God likes to obey the laws of physics again, that is possible, but then you are eliminating the usefulness of God and the other strategy is the vagueness of denying that we have any reason to expect something from God, denying that we can make predictions about how it might be the universe, so I have a quote here from Terry Eagleton, first he tries to say that God is the condition of possibility, the answer to why there is something instead of nothing, a concept that sounds ethereal, very abstract, but then he likes to say, well, God can repent.

God is an artist who makes things. of love and therefore you can't predict what God is going to do the problem is that you can't have it both ways you can't get credit for both for explaining the finely tuned value of let's say the cosmological constant and still say that God doesn't do predictions for other things we observe about the universe, multiverse theorists at least try. Here is an argument from an article where people who think about the multiverse predict the relic density of dark matter action in the universe based on the Multiverse Hypothesis. I don't especially think this is a reliable prediction in any sense, but at least they are trying.

I have never seen an image like this in a theology magazine. Nobody tries to use the God hypothesis. They can try to claim credit. for the low vacuum energy that allows us to exist, no one attempts to calculate the action density predicted under the God theory, so that is my conclusion, which is that God, as ontologically extravagant as the multiverse, appears to be God, is very much more problematic, it's a completely separate category it's not a type of physics, a type of natural process, it's a completely different type of thing, it's ill defined, it's unnecessary as far as I know and apparently you need to take or leave different predictions you could make depending on how they fit together is on the table as a logical possibility yes I think as good scientists we have learned over the last few hundred years that we can better explain the universe, thank you.