Physicists & Philosophers debunk The Fine Tuning Argument

[Music] our universe is filled with galaxies nebula stars and planets and perhaps most importantly living things but it's been argued that if the constants of nature were even slightly different then none of this would be possible and that this fine-tuning is evidence of a God that had to select the constants to be just right the argument is often expressed like this the fine tuning is vastly improbable under naturalism but not theism and thus supports the existence of God in this film we'll hear from some of the world's leading physicists and philosophers of physics who'll explain why they disagree [Music] we've had the Good Fortune to interview many of the world's leading cosmologists and what's clear is there is far less consensus that fine-tuning is real than Advocates of the argument LED on I think the specific dangerous argument because we have no idea what life would be like even with these numbers we don't know enough about life to know that it would never necessarily come about with the numbers that we see we don't know enough about it to say it wouldn't come about with other numbers so I think it's a dangerous argument to use there may be another reason why they have these values which is purely mathematical we just don't know so there are big questions here which are interesting to talk about but I don't think you can make any big conclusion from them we certainly can't even go from the standard model to the periodic table of the elements much less atoms and nuclei and complicated things you need to make life so what that means for fine tuning is we just don't have a once and for all ability to say with these laws life would be possible with these laws it would not the arguments that people have raised for many years about properties of water and properties of of chemistry and nuclear States and carbon um have all seemed a little bit unpersuasive to me because we don't know much about the details of life really and people say yes but if the constants were a little bit different there will be nothing and that's incredible intellectual arrogance and stupidity because nobody would be able today from the standard model to predict chemistry and life nobody at all so how do you know what would happen if you change the value of the cosmology of a constant imagine you change the mass of a pork you know a coupling of the Higgs a little bit of course there would not be carbon that would not be stars but there will be something else and nobody is able to say correctly and and plausibly Incredibly that the Universe would not be complex and whatever because we're not able to do this calculation one thing I've learned over the years working in philosophy is that you don't have to be convinced by an argument to be convinced that its conclusion is true and in fact I think it's a it's very good to have an incredibly critical attitude towards arguments you feel are bad if you're passionate about the truth of the conclusion so so in my particular case I I look at the Majesty of the Universe I look at the beauty both the beauty of the Manifest things around me colors flowers animals human beings but then the beautiful intricacy of what we discover through science and my immediate reaction is I'm not inclined to believe this is all just an accident I actually think in a way it destroys that entire driving feeling that actually I would say even drives me toward the scientific Enterprise to say I'm going to take that Transcendent thing and try to package it up and explain it away by some kind of argument for me it strikes me that that's the wrong direction here while halvorsan does not seek to of his theism with science others have not been so cautious perhaps the most viewed take on the fine-tuning argument was presented by our friend Justin brierley now what if I rolled this dice 70 times and every single time I got a six the chances of rolling a six 70 times in a row are around 1 in 10 to the 55. that's a one with 55 zeros after it now the odds of rolling 76 in a row one in 10 to the 55 as it happens those are the same odds of something called the expansion rate of the universe being just right for the existence of us here today it hit 70 rolls of the number six in a row first time and the expansion rate of the universe is just one among 30 or so other incredibly sensitively finely tuned constants and fundamental forces in the universe that must be just the way they are for the universe to be able to produce us the fact that we're here shows that someone's loaded the dice in fact maybe there's no dice at all what if the evidence points to this life-permitting universe actually being the product of an intelligent mind so in the case of rolling dice we're familiar we've all had the experience of rolling dice we know that there are different possible outcomes and if we're not skilled cheaters we know that when we roll the dice the number of six comes out approximately one time in six but we have no experience like that that is relevant to assessing the probability of the constants of nature following the constants of physics falling within some narrow range we have never observed other universes where they take on different values we haven't observed repeated trials of universes being created by the same processes to see what values the concepts of nature take in those other cases so we don't have any basis to assign a probability in the case of the constants of physics you roll a die you know the probability distribution if it's a fair die you know it will be 1 1 6 of the time 2 1 6 at the time Etc in the case of cosmology or fundamental physics that's exactly what we don't know we don't know what that probability distribution is so without that all the analogies in the world are not helping us very much when people bring up the notion of fine-tuning what they have in mind is they look at the world around them and they say the universe around them and they say um gee it seems so unlikely so the question is what is that notion of unlikely that they're employing there's a few different ways you could try to say that's what we mean we say something probably most people nowadays will think that there are at least two different Notions of probability they're often called objective and subjective but um the objective one is something to do with what happens in the real world and the subjective one is one to do with degrees of belief so I might believe different things to various degrees I might be more confident that it will be sunny tomorrow in Los Angeles than that the Los Angeles Dodgers will win their baseball game the most common understanding of an objective probability is a frequentialist one we know for example that with human births more boys are born than girls so they're even though they're two possibilities and you might naturally think it's going to be 50 50 actually they're slightly more boys born than girls the other takes on probability one was Carl Carl popper he said a probability is actually a propensity in a thing so a thing has this feature that it has certain Tendencies so you see there's sort of problems for all of these accounts of probability for pulling off a fine tuning argument frequency how many we don't get an infinite number of universes over and over again at least most people don't think that it's just one it's we have one universe so how could it be something that's probable or improbable according to long-term frequency for subjective bayesians who cares what the probability is because it actually doesn't it's not something in the world and it can't convince people because if they think this universe is likely well that's their opinion and then propensity also runs into this problem that before the universe exists it can't have a propensity to be one thing or another so it does actually look like fine tuning has slightly Shady chances on any of the standard accounts of probability there are different cosmological theories about the origin of the universe but none of them really posits a mechanism that can generate different universes with different possible values of those constants such that we understand the probabilities of getting those constants in Falling within different ranges so we don't have an analog of the roulette wheel in order to avoid these problems fine-tuning Advocates often appeal to something called the principle of indifference the Prisma difference says in some sense that if we're indifferent between two hypotheses then we should assign the same probability to both of them but there's many cases in which that's going to give us inconsistent results for the probability assignments that we make so for example seven days in the week um you don't know what day it is it could either be Monday or not Monday and you've got no way of choosing between those two things so the probability that it's Monday has probably half so the property of Tuesday is a half the property Wednesday is the half and so so applying the principle of difference you just get inconsistent results and things get worse for the constants of nature as we could imagine them taking on literally any value another problem with the principle of indifference is that when we're dealing with a case where there are infinitely many possibilities there's no way of assigning equal probability to every one of the infinite possibilities in order to do that you have to introduce some mathematics called measure Theory and there are many many measures which will give different results you need to assign a numerical value to each event representing the probability that occurs a measure is a mathematical notion and basically it's a way of assigning numbers to things problem isn't one of defining a measure per se the the question is what meaning could such a measure have could that correspond to anything that was physically meaningful or even psychologically meaningful there's not to my mind been anything resembling a convincing argument that we have the one true measure that anyone can say this is the thing we should ask if we want to know are you know is our universe fine-tuned we should be indifferent about them and the only way to do that is assign them equal probabilities that's all great and good we're only cosmology that easy if you assign them all equal probability uh if you give them any fun at probability they've got to add up to one and that can't if you if you take any infinite number of Planet quads quantities they are up to something that's infinite if you want to normalize and make sure you get a value of string zero and one you've got to say that each thing has zero probability but then we hit the problem of dividing by zero um but on the other hand if you give them a probability greater than zero then they're going to add up to something infinite so I mean either zero or it's infinite and um neither of those is going to work ironically two of the most significant critics of the fine-tuning argument who pointed this problem out are Lydia and Tim McGrew I think that that actually was a quite brilliant move and a move of incredibly high integrity because you know Tim and Lydia McGrew you know they're well known you know the theistic philosophers to come in and say we're and the way I actually say it was quite inspirational to me to see them enter into the debate with some of their peers and say look we're not against you in principle but we don't like the argument you're pulling off right now let's raise the standards for the argument so so basically they're they're um main objection here is that again if you have infinitely many different possibilities what you consider to be the right way of assigning probabilities as different possibilities is just not given in advance for these kinds of spaces you're going to have to bring in some kind of contingent assumption which actually just spoils the whole argument Rob Collins has suggested we ignore the infinancy of possibilities and focus on what he calls the epistemically illuminated region or The Limited space where we can estimate whether the constants are life permitting I think Colin's argument is just a mistake maybe the right epistemic probably to have once you see the dart hit it is to think that the probability of a dart hits the illuminated region is one because you've just seen it hit the origin one before it hit there what should your epistemic probably be beats me I don't think there's any particular epistemic probability to have are we saying there's epistemic justification from physics that possibilities outside of this aren't relevant to the discussion and if so why or are we just talking about um we for some reason are throwing away a bunch of the other possibilities you know we're not taking those other possibilities the ones outside the epistemically illuminated region we're not taking them seriously and my answer is the more you make the argument subjective based on current knowledge where the less Force the argument has if we see somebody hit the bullseye repeatedly we think aha they must be very good at darts but again if we knew nothing about this process if we knew nothing about darts or dart boards or the physical processes by which darts were sent to dart boards we wouldn't be able to infer this a more unconventional suggestion is to Simply give up on the idea that probabilities have to sum to one we'll drop the requirement that if we sum accountable number like the natural numbers one two three four if we sum all those possibilities those will sum up to one we can drop that that stops the objection in one sense the objection has the McGrew objection has revenge because the thing is the best you can do in some sense is assign those events all zero and still say there's something will happen but they all have chance zero now once again the debate can go on because clever Defenders are fine-tuning they might go to something like we're going to go to infinitesimal numbers numbers smaller than any finite number are the chances of the different possibilities at that stage and I I love mathematics as much as anyone that's a stage where I say this sounds to me like we've gone to ptolemaic episidicals in effort to defend the argument it feels to me that that too much is being done to try to save getting life permitting values for the constants is often compared to winning the lottery but with no bounds on what values the constants might take this is an infinite Lottery and what are the odds of winning that mathematicians often distinguish between what is called the countably infinite and the even larger set which is uncountably infinite it's even worse than the case of an infinite Lottery infinite Lottery if you get to something like a constant of nature because again we tend to think these constants we see no good reason to say they're restricted to a finite region they could be anything but now we have not just an infinite Lottery we have a lottery with uncountably many infinitely all the decimal numbers it could be that the constant could be that decimal how do we choose what the more likely possibilities are we have no rational a priority way to do that it's not totally hopeless because we might hope that physics has a reason for choosing some measure over the other in most of these cases in many of these cases there could be a measure that is there could be a way of saying this chance is more likely than that one and so on but we're going to need physics to give it to us we're going to have good reasons coming out of physics and indeed in many cases physics has shown us that what seemed to be extremely improbable ends up being extremely probable philosopher of physics Tim Maudlin illustrates this with a hypothetical skydiver let's call him Phil who seems to spend his entire life in free fall they're feeling wind all the time and so on and they don't develop enough physics to figure out how much drag there is and they realize at some point that the force of gravity downward is exactly and precisely balanced by the drag upwards so they're not accelerating they're falling at a constant rate and if you think about that balance it looks wildly unlikely because the force of gravity is just given by how much mass they have but the drag is given by you know how how their hands are spread out and what they're wearing and all these little details of the of the air going by so you might say well what are the chances that they downward and upward forces would exactly balance and the answer is well they had to because they didn't when you started falling and then you kept falling faster and faster and building up the drag until they balance so this is a case of homeostasis this is where no matter where you started you'll be out of balance at the beginning but then the system itself will naturally go to balance and and stay there and so there's nothing miraculous about it even though it would look miraculous if you just did the calculation we can't just calculate probabilities a priori we need to have some understanding of the mechanism that produces outcomes or some kind of pattern of repeated trials that we can use to estimate a probability so as an illustration here's a jar and it contains both black beans and red lentils it's kind of a vegetarian's delight with mixed legumes so suppose I were to shake this randomly what's the probability that all of the black beans would come out on top or would be in the top half of this layer of the jar well we might try to compute that a priori the probability that any one black bean will be in the top half of the jar is one half and since they're 100 of them the probability that all 100 of them will be in the top half would be one half to The One Hundredth so this is an astronomically small number so what happens when we shake what's going on well we understand the process here these beings are in a gravitational field they're moving about but there's a force that's trying to pull them downwards and the little tiny red lentils are small and they're able to kind of fall down through the nooks and crannies that the bigger black beans create and so this process it's random in the sense that it's not directed There is an intelligent agency behind it but it's a process that's taking place under a bias that is leading towards the red lentils to go to the bottom and the black beans at the top and you have to understand the process to know that this outcome is in fact likely it's in fact what you expect and this number that you calculated a priori doesn't really have anything to do with what's going on inside that jar during the uh 18th 19th centuries uh astronomers noticed that all the planets travel in the same direction around the Sun in an elliptical orbit that pretty much at the same plane given all the possible ways in which planets could travel around the Sun uh in a comfortable conformance with Newton's laws of gravity this looks like very special why is it like that and in fact there were some philosophers I think Emmanuel Kant was one of them who used this as an argument for the existence of God later LaPlace constructed a scientific explanation he gave an account of of the formation of the solar system according to which is called the nebular hypothesis which said that the sun formed out of a ball of gas the rotating gas and the planets were thrown out from the Sun as the sun was rotating and so at Naturally since it's rotating in a particular way they'd all be thrown out at the same angle all traveling in the same direction another case is the very example Justin gave in his dice video it's also known as Dickie's flatness problem as it's related to the fact that a flat universe which allows the expansion rate to be just right is unstable like a pencil balancing on its tip but the theory of exponential expansion known as inflation solves this okay just get inflation started and it will do all the heavy lifting for you uh it'll make the universe really big um so it will make the in particular it'll make it very flat because if you imagine like a a curved thing and then expand it to be really really huge it looks locally flat just like the earth looks flat to us because we're real small compared to that inflation was originally thought to be driven by a phase transition known as supercooling and as Alan Guth wrote in 1979 this kind of super cooling can explain why the universe today is so incredibly flat and therefore resolve the fine-tuning Paradox pointed out by Bob Dickey so the original flatness argument from Dickey was if you start with a little bit of curvature of space in the early Universe it becomes more pronounced more noticeable over time unless you have inflation which pins it back to zero curvature but the question that we need to ask is what is the probability that the Universe would have started with a little bit of non-zero curvature and again we don't know the answer to that like that's a very hard question to ask but general relativity is our best theory of gravity and cosmology it's a classical Theory there is something called The leoville Measure there's a particular measure on the space of trajectories that you can calculate and when Dicky did this or when other people who do inflationary cosmology think about the flatness problem they don't bother to actually ask what is the measure and therefore what is the probability when you do you find out that with probably ability one if you choose a universe randomly it will be spatially flat the counter factuals don't give you the probabilities if I'm playing craps and I lose I can say if I'd rolled a seven I would have won that doesn't tell me anything about How likely or unlikely it is that I of rolling a seven so we can do the thought experiment and imagine a universe like ours with the same laws of physics and principles of physics but with different values for those physical constants that might tell us what would have happened in such a universe it doesn't tell us whether those values of the constants were probable or improbable because multiple constant is probably the best candidate we have for pointing at something and saying here we could imagine this being very very different if it were very large or very large and negative there's just not enough time there's not enough ways to make a planet much less a living being that's very very plausible what we don't know is How likely is it that the cosmological constant is big or small or anything like that we can make a guess and that's good and we can make progress on the basis of that let's just not get too confident about it that presumption that the the relevant quantity could take a big range of values it's completely pure apurate has no basis in a scientific judgment there is a reason we call constants of nature constants of nature our theories as they are they uh they have some parameters in them that are constants um we can imagine uh other scenarios where their constants were different but uh we don't really have a good theory of how this could happen or if that would happen so that's really a matter of speculation and there's really no way of knowing if you think that there is fine-tuning for the constants of nature in our universe to allow for the existence of life this is excellent evidence in favor of naturalism as opposed to theism because if you think about it in theism God can do whatever God wants God is Not constrained by the laws of physics God does not need the laws of physics to allow certain physical configurations to exist in order for there to be life God is infinitely powerful God can do whatever ever the only Theory under which the physical conditions need to be exactly right to allow for complex chemical reactions in biology and life and so forth is naturalism it's under naturalism that you need the constants to have the right values in order for life to exist under theism life could exist under any conditions whatsoever why does God need a whole universe there to bring life about he certainly doesn't that he could just wrote about New York City in fact if I was God that's what I would do who needs Los Angeles fine-tuning arguments strike me as very unprincipled in where they're willing to have omnipotence play a role so you could imagine for example a really wild scenario where like God just said well I don't need to go to any of this trouble to have there be assembled atoms and molecules and then biological systems and why not just take something like electrons and endow them with Consciousness I mean God can do that right as soon as you say God can't do that I think the the the theistic arguer is in a very hazardous situation God's omnipotence the very thing that allows us to assume he can change the constants of nature is also the very thing that robs him of any motive to do so in response to this line of reasoning more sophisticated Defenders of fine-tuning describe it as not for life but rather the existence of embodied moral agents the claim has sometimes been made that in order for us to be able to commit morally significant actions we need to be we need to have physical bodies we need to be physically embodied there are at least two reasons why I don't think that that claim is plausible presumably if we were Souls without physical bodies we could still harm each other in ways that in some spiritual realm the other way in which I don't think that this is true is if we accept the Christian view that there are such things as as angels and demons and so on that those beings are capable of doing moral wrongs so for instance Satan was capable of rebelling against God and falling and so forth and yet Satan is supposed to be a physically disembodied Spirit if Satan is a physically disembodied spirit and was capable of doing wrong then apparently it's possible to do wrong without being physically embodied there were theists historically who thought that it was a bad thing that we are physically embodied so for instance the gnostics the early NASA Christians thought that the deity of the Old Testament was a separate demigod from the god of the news Testament that I had sent Jesus and that demigod from the Old Testament was the god that was responsible for our physical embodiment but that the god in the New Testament is a God that we can um that we can come to only by overcoming our physical embodiment true that our physical embodiment was a bad thing then it might be quite surprising that uh that God would create us with physical bodies if the higher God never intended for a physical Universe to be created then having a landscape where creation would have Hazard creation could make something that's not intrinsically good would be almost what you'd expect for the Gnostic God now the lower now this may be where it gets very exciting because you say now maybe it would be almost like the problem of evil and the fine-tuning argument both could be right in some sense because you'd say the the the lower God comes along and they're going to do something that's not at all the Perfection which would be to just leave nothing created so it's going to both have the evil but also it's a sign that there is this fine tuning because they at least wanted to get beings Like Us in the picture so you know I think there could be a very good case made that what you actually get upon consideration is something more like gnosticism a key point to note then is that the fine-tuning argument can only get off the ground if we assume that the creation of the physical universe is something a good God would want to do but what gnosticism shows is that that doesn't follow from merely postulating God's existence if I flip a coin and it lands heads I can think of a hypothesis that explains that perfectly namely an all-powerful God who intended for the coin to land heads and that entails that the coin lands heads because all powerful God can't fail to realize these intentions but this is rendering the the whole process trivial um it's like firing an arrow a tree and then drawing a Target around wherever the arrow happened to land because I I could just as easily I can always add a hypothesis like that following the discovery of anything say if I find that there's some trilobite at the bottom of the ocean that we weren't expecting to see well that's explained perfectly by an all-powerful God wanting exactly that trilobite to be exactly the essay whatever you can always just ad hoc add on these types of entailing hypotheses after any empirical data whether it's about the hospitability of the universe or the way that coin lands what's going on here is a kind of abuse of probability Theory rather than generally defined deriving probabilities and expectations based on hypotheses it's constructing hypotheses to fit things we've already found I think the fine-tuning argument can sometimes backfire in a way that hasn't really been noticed by people who put it forward and that is if you take as an assumption which which I actually think is theologically very well motivated that not only does God have a say in the game if God exists but that God has a say in setting up the rules of the game so the way you can put that in terms of cosmology is not only does God get to choose in some sense which of the universes comes about but he actually has a say about which are more or less likely to come about imagine that you believe in some some infinite being who designed some sort of game for you and and you believe also that this being um so I think in a paper I wrote some time ago I actually call this being Gob um so Gob just for just for fun now imagine that you before you you play the game you think gob really really likes perp The Color Purple right so God really likes the color purple he hates the color yellow once you you're going to play this game where you're going to draw a ball out of a hat and and you know this is the preference Gob is averse to Yellow loves purple okay so now you're gonna play the game but the game is to figure out does who set up the game okay so you're gonna play You're Gonna draw the balls out of the Hat now of course naturally we think evidence for gob's existence is you draw out a purple ball because Gob hates yellow likes purple okay so imagine how you're going to play the game you reach down in you pull out a ball and it's purple and you go okay I have a fine tuning argument right Gob exists because I got a purple ball that's evidence that God exists now imagine you get round two of the game now you get to look inside the Hat every Ball but the one you pulled out was yellow every single one now what do you do what's your feeling about gob's existence I think the obvious answer is it's a big defeater to the claim that Gob exists but this is directly analogous to the fine-tuning argument because what we think is we got super lucky we pulled out the universe analogy of a purple ball a universe in which life exists however we look at the landscape of possible universes and this incredibly rare possibility my reaction which I think in that case is that's our that's evidence against God's existence in other words if God sets the probabilities for life and loves life we should expect the probabilities for life to be high fine-tuning is the claim that the probabilities for life are low yet Advocates of the argument like Luke Barnes claim that life would be likely given theism a lot of other things are likely namely that if God is supposed to be the benevolent guy he's said to be that it's likely that there wouldn't be a holocaust but we know that it's not true so if we think of that as a hypothesis as Luke Barnes was suggesting it's been refuted not once not twice but a trillion times over let's say well it's it's probable it's pretty probable that there would be embodied physical organisms given that there's a God and you might wonder how do we know that that's probably we have an independent way of establishing that shouldn't we be skeptical about that now compare that to what they say about the problem of evil given the idea of an all-good all-powerful God you might think yeah it's really improbable that there would be such bad designs so many design flaws and so much suffering in the world and yet they want to say oh no you don't know enough about what is open to God what God's intentions are and what God's Ways and Means are to rule out or to sort of say that that would be improbable well how do you get this knowledge it seems like they help themselves to it in the one case when it helps their overall position and and say oh we don't have it when it would hurt their overall position and that seems to be kind of arbitrary in a way the fine-tuning argument depends crucially on the assumption that God favors life-permitting universes if you accept that you very quickly run over to God would favor a universe without lots of suffering and things like that so you're in Jeopardy here the extent to which you buy into fine tuning you're going to run to the problem of evil if there's a designer what's the designer interested in designing now if you say life why life because I'm alive why oh human beings the god the designer really wanted human needs went through all these billions of millions of years of of dinosaurs to get there that doesn't make any sense right that's just egocentrism we put ourselves at the center of the thing that needs to be explained one way of motivating the idea that God has done specific intentions is to say that God is like good something like that but then why think that God is good well one classic way that people have done that is to appeal to say an ontological argument which is trying to show the God is a perfect being right but if you've already got an argument that establishes that God is a perfect being and therefore exists you don't need to run the fine-tuning argument which doesn't actually entail the God exists it just raises your expectation that God exists so why bother with the fine-tuning argument if you've already got a deductive argument that proves that God exists there's no point to it if you need a stronger stronger argument to support a weaker one week one is redundant many theologians suggest the universe could not produce Life by purely natural means but it's hard to see how this can be squared with the claims that it's also fine-tuned for life after all we wouldn't suggest that an object is perfectly designed for flight if it needs a miracle to get off the ground that there is no Theory not even a shadow of a theory that will explain the origin of Life on this planet and that the evidence is quite consistent with thinking that the origin of Life requires some sort of miraculous intervention by God on the one hand we can see cases where nature is designed well you know and we say that must be the sign that God did it on the other hand we see cases where nature is insufficient and we might be tempted to say so God had to do it God had to breach the Gap they want the parameters and so on to be set up so that by itself nature would lead to life so it's almost like they're saying there can't be a we're going to ignore the fact that we traditionally have put a miracle here now we did a miracle earlier namely the miracle that we got the constants that permit life it feels to me like we're we're playing a non-principled game here to think that we have empirical evidence that the constants of nature are the kind of thing that we would expect to be the product of intelligence we have no evidence for that we we just have never seen anything like that produced by intelligence the German metaphysician leibniz he actually said a miracle would be evidence against God's existence because God would design a universe that was so perfect it wouldn't need Miracles another way to formulate the argument is to suggest that the fine-tuning is due to necessity chance or design and then try to rule out the first two options the most promising candidate for a theory of everything to date super String Theory or M Theory allows a Cosmic Landscape of around 10 to the 500th power different universes governed by the present laws of nature so that it does nothing to render The observed values of the constants and quantities physically necessary we certainly can't say string theory predicts something and therefore it's true we don't know whether string theory is true we don't know what string theory predicts these are the two major problems there so when it comes to what string theory predicts I think we should take it very seriously it seems to predict there's a landscape of different possibilities but there's plenty of string theorists out there who doubt that and they're trying to understand that and it's very hard to do string theory is really a speculation about the nature of quantum gravity even though it's it's the leading proposal it hasn't really been tested in any way if String Theory itself cannot explain through necessity the values of the fine constants then maybe so much the worst for that Avenue in solving the fine-tuning problem perhaps it can perhaps there'll be another theory that will prove better than String Theory so all of these questions are entirely open and therefore we cannot rule out necessity so if it can be shown that it's necessary that the constants of nature take the values that they do then I can imagine somebody saying well then why did they take those values isn't that itself a sign of intelligent design I think that's a different argument because that's not trading on the improbability of the constants taking on a certain value now you could come up with some speculative other Theory maybe there's an infinite number of universes giving you an infinite number of chances to roll the dice Maybe but we don't have any scientific evidence for it so if you're hanging your hat on that possibility then you're every bit as much committed to a faith position as the person who says God was behind it comparing the Multiverse to God is not really a fair fight in terms of thinking about hypotheses and theories to explain the universe because the Multiverse as unclear and uncertain as it is we have no direct evidence that it's out there it's a scientific hypothesis we have equations that tell you what happens speak to the Multiverse problem Dr Lennox my instinctive reaction is it is the biggest violation of the principle of Occam's razor we've ever seen in other words that principle that we normally use in science and in our investigation that we keep the number of hypotheses as small as possible point that a lot of Skeptics about the Multiverse don't understand is that you don't postulate a Multiverse that's not what you do that's just a mistake they're getting it wrong what you postulate are laws of physics that give rise to a Multiverse it would be like complaining that there are too many integers you have zero and one and two and there's an infant number of them that's crazy talk that misunderstands what the integers are you start with zero and then you have a rule for making more within physics and cosmology that's where the Multiverse comes from there's no scientific evidence for the existence of this Multiverse it cannot be detected observed measured or proved okay if that solution is no good for you because it can't be tested oh very good that's very good that's amazing I agree fully um we cannot test the idea that changed the fundamental parameters you don't have life we're going to call uh foul at speculation for a Multiverse Theory I think I'm going to call foul at speculation about what occurs with small changes in the constants or changes in the constant of nature Multiverse hypothesis is relatively new and really what it is it is a response to the fact that the Universe appears to be so designed nobody would be thinking that there are other universes out there unless they realize wow this place is so designed we've got to multiply our chances that this could have happened without intelligence if we're going to say there's no God this claim is simply false while the Multiverse is still controversial and we'll hear from both supporters and detractors it was not invented to deal with the theological fine-tuning argument but it seemed to arise naturally from inflationary cosmology once inflation starts it just never stops and the way that works is actually fairly simple uh inflation is a is driven by a kind of gravitational repulsion which is in turn created by a certain peculiar state of matter and this peculiar state of matter that creates gravitational repulsion is unstable so it decays pretty much like a radioactive substance decays just randomly without any way of really predicting one it will suddenly start to Decay and this Decay starts locally small patch um so if you wait for um one half-life of this Decay then really by definition half of the space that you are looking at that was inflating uh will no longer be inflating but the catch is that the exponential expansion goes on all the time uh so for the parameters that are appropriate for most versions of the theory uh during the half-life of the Decay the region that is has not decayed has expanded by a factor much much larger than a factor of two uh so at the end of the period you end up with more space inflating than what you started with even while it's decaying and this goes on forever whenever a Decay takes place that really creates a local Big Bang it's a local Universe which we sometimes call a pocket Universe in this context to distinguish it from everything and these pocket universes go on being created in the context of these theories um adding finite following NASA's CMB probe debut map declaring they had detected a key signature of inflation Issa launched an even more advanced follow-up mission called plank George of statue was the cosmologist chosen to present its cosmology results you know the simplest models would have internally inflating universe and Clinic favors yeah so when I hear all the time on TV there's no evidence for a Multiverse what you're telling me seems to acquire there is and if so if inflation is eternal then uh then you have a Multiverse that um and and so and that's why I say that you know I think this is the most important result from from Planck um where we're sort of being pushed towards you know now experimentally in the direction of a of a Multiverse now a visible Universe we think that life does not arise uniformly in all places uh but life only arises in very special places um and there's every reason to think that in the Multiverse it would be the same way most living things would see laws of physics low energy local laws of physics that would be conducive to life um and it would not be because the laws of physics are actually fine-tuned uh but just that life only forms and those particular kinds of vacuum which are suitable for the creation of life in the 1980s Nobel Prize winner Stephen Weinberg used the idea of a self-selection effect in a Multiverse otherwise known as anthropic reasoning to predict a small value for the cosmological constant it came as a shock to most physicists when the and tropical the projected value of the cosmological constant was actually observed and this changed many Minds I do think that weinberg's prediction really of a value of the cosmological constant which is non-zero a bit close to zero was extremely striking I think it greatly impressed the community and made us all believe that gosh there's something too anthropic reasoning and it might really deliver while inflation is the mainstream view of cosmologists it is not without its critics who propose Alternatives which we've documented in our film series before the Big Bang many of these critics deny that fine-tuning is real others suggest that alternative schemes can also give rise to an ensemble of universes what CCC is a different picture it's a sequential you say the different eons one after the other but not next to each other in this other sense and one possibility might be that in the eons of CCC these numbers have different values and there's this thing called the anthropic principle which might say well we're only in that Eon where these numbers have exactly the right values where life could come about and if you change monkey with these numbers too much life wouldn't happen given this our friend Justin brierley author of the infamous dice video invited Phil and the Christian apologist and physicist Jeff zwyrink onto his podcast unbelievable I'm ready to hold my hands up guys and say if if I um jumped the gun as I think probably it would be fair to say lots of other people involved in Christian politics by saying there's no scientific evidence for a Multiverse in that in that video then I'll hold my hands up and say my bad if this is true I may have I I may just have to say that we don't have a fine-tuning argument right now and so I think that is something as Christians we need to wrestle with pretty seriously one criticism of the Multiverse is that the Universe generator itself would require an enormous amount of fine-tuning exactly what justifies this is not clear but it may be related to the claim that inflation is unlikely to start in the first place there has been some debate in the physics literature about how probable it is for inflation to start my point of view really is that that discussion is pretty much just irrelevant if inflation has a high probability of becoming Eternal because Eternal gives you an infinite factor for the space-time volume that comes out of inflation and infinity is a large number and I think that makes it pretty much irrelevant How likely inflation was to start as long as you think that there's some non-zero probability of it starting for the people who do play that game uh people reach different conclusions because in truth we don't have any theory of the actual creation of the universe so people make different guesses and come up with all kinds of answers some saying inflation is very likely and some saying inflation is highly improbable the main argument against Multiverse hypotheses that are being floated today in cosmological discussions and the idea is this um it is far more likely that a single brain would fluctuate into existence out of the vacuum then that a universe finally tuned like this at a low entropy condition would come to exist you would get both men brains even if there was no Multiverse at all it's the idea is you just wait long enough you don't change the constants of nature or anything like that you just have a a a soup of these individual molecules floating around in space and you give them an infinite amount of time and only a finite amount of space and they'll eventually Bang into each other the right way to form pretty much any structure you want this has nothing to do with the Multiverse at all it's entirely orthogonal question one way out of it is certainly to except the notion of a Multiverse that our universe is not the only one but one of many pocket universes and then the Volkswagen brands in our universe can be outnumbered by normal life in parallel universes and for many kinds of measures uh the boltzman brain problem can be solved the boltzman brain problem is weird in how people have sort of latched onto it it's a very specific problem if a very specific set of things happen namely the universe lasts forever and as it's lasting forever there are random thermal fluctuations within it then we should get boltzmann brains and we should have a very different Universe than what we see but neither one of those assumptions are automatic even if you believe in a Multiverse maybe it's a finite amount of time but much more likely the way the Multiverse exists and evolves over time is just completely different than random thermal fluctuations that's a very easy thing to set up so the Bolson brain problem is not a statement that the Multiverse is in trouble because there are too many boltzmann brains it's just just a statement that you should avoid those particular versions of the Multiverse which are dominated by boltzmann brains that's not that hard to do it's not a big problem get over it as Roger Penrose has pointed out while Multiverse or anthropic reasoning might address the fine-tuning of the constants it can resolve the apparent low entropy at the beginning of the universe I'm of the belief that the fact that our early Universe had low entropy is a huge problem for modern cosmology problem in the sense of a puzzle we need to solve not that it's unsolvable it's extremely solvable I have suggested solutions for it with my colleague Jennifer Chen we proposed a Multiverse model which would explain why our early Universe had low entropy but the anthropic principle does not by itself solve it with that I agree with Roger Penrose because the early universe's low entropy is much much lower than it needs to be to allow for the existence of life so I would take that as a strike against those who want to explain fine tuning using God because here's an example of a fine-tuning that was not just for us to exist right it was clearly some dynamical mechanism that has nothing to do with the existence of life yet we have some fine-tuning to be explained it could very well be that other fine tunings have similar dynamical explanations pretty pretty gross course tuning the the entropy in the gravitational field is ridiculously small compared with um the entropy in Mata uh it's there's nothing fine-tuned about it it's just huge yes people had argued there are these constants that's fine-tuned for life and he said well hang on look at the entropy that could be much much higher and life would still be here so that's not an attitude for life therefore we see something about good it isn't I absolutely agree with that I absolutely agree with that yes Sean Carroll has constructed a model which uh adds an more to the universe which uh explains how it is that our our universe would have formed in verse with very small entropy and Roger Penrose has constructed a different model based on his unconformal geometry and his uh and black holes uh but so and there may be other ideas around and indeed Loop Quantum cosmology and the big bones so it's another potential in the quadratic Branch because the Dynamics is different from Einstein's theory a horizon develops but it grows extremely rapidly and in fact therefore the entropy a really grow extremely rapidly and and as usual with black hole Horizons this entropic dominates completely the entropy of matter therefore the entropy is really growing very rapidly but then at the bounds the geometry is such which is not trivial statement is such that in fact the area of this Horizon becomes infinite and then after that The Horizon simply disappears so if you like what one has to do is to reset the entropic clock in a certain sense at the bounds if fine tuning is real then it suggests the constants of nature were not chosen randomly and only once but there's nothing in naturalism that says that has to be how the constants were selected one of the critics of anthropic reasoning is Lee smolen who's developed a model of cosmology known as cosmological natural selection where the constants of nature are forced into a life-permitting range Lee smullen several times in his career has introduced ideas that amazingly address or even solve problems that no one's had an idea of any inkling how to do it not that he's right in his Solutions but it's a possible solution and for that I give him great credit and the case of cosmological selection I think is an example it's a way of solving fine-tuning problems but without introducing uh as an observer selection effect I saw this as a problem akin to the problem of biology which is to explain why the different creatures in the living world are so fit if you imagine that the parameters of the standard model are like the genes then with different choices of the genes you get different organisms in different ecosystems with different populations of organisms the animals or the organisms are fitter than they would be under a random change this seems analogous to the claim that the universe is more complex and more hospitable to life for the present values of the parameters then for random values of the parameters so I wondered whether there could be an explanation akin to biological natural selection which would apply at the scale of the universe as a whole cosmological natural selection offers the idea that a new universe comes into being a singularity of a black hole each universe is equipped with a set of parameters the parameters of nature that govern the physics in that universe and the parameters change a little bit between the parent universe and the new universe there is a set of parameters it is postulated that maximizes the number of black holes formed uh in a universe in a given universe and therefore maximizes the number of progeny that it produces if you have a biology of this type for universes then you could then apply the theory of evolution and to the universe as an Ask okay so what is the fittest kind of universe that you could have and if you just follow very naively the same thing that you do in evolution basically the fittest life form is the one who can have most offsprings so which is a universe could make most black holes right so that that was his idea that basically you're not really uh fine-tuning for life but you're really fine-tuning for more and more black holes although Stephen Weinberg predicted the value of the cosmological constant using anthropics Raphael Sorkin also made the same successful prediction on the basis of his theory of quantum gravity known as causal set theory which posits that there are atoms of space and time recently it's been suggested there's a link between causal sets and cosmological natural selection I studied whether cosmological naturalization could be compatible with puzzle sets Theory The Singularity is what separates the mother Universe from the progeny once we Define those structures we studied the Dynamics of causal sets around them so the Dynamics and causes that theory is given by a set of parameters which in this model play the role of the parameters of nature and we've shown that there is a process of change you can repackage the parameters in a different way on each side of the partition or in each in each universe and so this idea of changing of the parameters of nature across the singularity was echoed in those ideas police Mullen also claims that his model makes predictions for astrophysical data the prediction is that a universe picks a constant such that the maximum mass of nutrient stars is this small as possible so Lee's suggestion was that it cannot so the maximum Mass cannot be bigger than two solar masses we've now observed neutral stars that are just as massive as that um so it's kind of an on the verge of that prediction we know that possibly but then really the question is is how how sharply you can put that value because there's a lot of uncertainties and the real uncertainty is what what is what is the type of the nuclear matters that you could have so there's a the main uncertainty impact in this game is that what's known as a nuclear equation of a state and the maximum Mass good value by by 100 basically depending on what what choice you make and then the other question is that could there be different types of um nutrient stars with different equations of the state so if you detect a nutrient star with I don't know two and a half solar masses does it mean that that's the maximum for all the neutron stars or there could be different types of nutrient stars that some of them are much more susceptible to form a black hole so we don't really know that's that's the uncertainty here the difficulty with raising God as explanance we philosophers we have the exponentum the thing we're going to explain and we have the explanance if God is the exponents on the basis of intent to bring about what is otherwise seems enormously improbable then we have an explanation for absolutely everything that we might be baffled by as sort of a universal explanations for a a a endless explananda Without End this is part of the reason why I think it's rather it's rather it is a bankrupt policy to appeal to God at the level of detail if we do that we are really infantilizing ourselves it's contrary to our entire experience after two and a half thousand years of science this isn't how we make progress this isn't how we deepen our understanding and it isn't how we give genuine explanations for fine-tuning it's not clear that there's a problem to solve and if there is there is no shortage of solutions none of which have been rolled out the constants might be set by necessity or by chance in a Multiverse or they may be selected via a darwinian process or perhaps some other mechanism yet to be discovered and at the moment we can't say which of these are true but that gives no justification for accepting the conclusion of the fine-tuning argument

Channel: Phil Halper (aka Skydivephil)

Views: 78,044

Keywords: cosmology, physics, god, atheism, multiverse, the fine tuning argument, debunking the fine tuning argument, sean carroll, carlo rovelli, roger penrose, hans halvorson, philosophy, debate, debate God, entropy, fine tuning, fine tuning argument, fine tuned universe, skeptic, quantum, fine tuning of the universe, Alan Guth, inflationary cosmology

Id: jJ-fj3lqJ6M

Length: 59min 44sec (3584 seconds)

Published: Thu Nov 17 2022