Paul Davies - Are the Laws of Nature Constant?

Paul whenever we try to really discern what it's all about we always get back to the laws of physics the laws of nature and most would impose that as fixed and final on the universe and therefore the hint and it's only a hint that some of the most fundamental laws might have changed over the course of universal history which is not sure but is so startling and disruptive how do you look upon the laws of physics are they necessarily constant for a long time I was an ardent place honest now Plato gave us the notion that mathematics has real existence but it's not an existence within the universe it's got its own sort of realm outside of space and time so statements like eleven is a prime number or an equilateral triangle these are real statements and objects but they're not real in the universe physical universe if you try to draw a triangle or a circle in the physical universe it's always an imperfect representation of the perfect real circle that the exist in this platonic realm and most physicists who work on fundamental issues have taken on this sort of platonic view and they regard the laws of physics as mathematical statements existing in this platonic realm where they can be perfect mathematical statements infinitely precise and that mother nature who applies these laws of physics does her computation in this platonic realm and not in the real universe and the relationship between mathematics and physics has always been a very curious one because as Galileo said the book of a great book of nature is written in mathematical language and so you have to be versed in mathematics to interpret it why is it that the laws of nature are mathematical and then we can ask for why those laws why those particular mathematical statements and not some others and so we had this image that mathematics is some fast warehouse of mathematical forms and relationships and mother nature goes along with the shopping trolley and says oh I'll have that differential equation there and I'll have that symmetry group from I like this particular geometry there and then goes off and builds a universe with those concepts making the laws of physics from those perfect mathematical stats right and then leaving all the rest of it behind you see and so this raises the question well why did Mother Nature choose those particular forms and not some others and gets us into all sorts of mischief so that is the traditional view that the universe came with an absolute fix Universal set of perfect mathematical laws immutable stamped on like the creators mark at the beginning and unchanged ever since but I've abandoned that notion of physical law I think it's ridiculously idealized it can never be tested we can't ever show that the laws apply to infinite precision I think there's very good reason to think that these laws are limited in their fidelity and the reason is that the rules of physics are really informational statements they tell us things about the universe they give us information about how nature operates and when we go to the modern concept of information we find that it's related to things like compute ability and software and all of these things that we're familiar with from the information revolution and so if we think of the laws of physics as being really like information or like software then as everybody knows that any man-made computer is limited in its computational power there's always rounding errors and inaccuracies and certain finite fidelity in the same way we should find that the laws of nature subjects are similar limitations so that opens up the possibility that if the laws have a certain intrinsic fuzziness might we detect some flaws in the laws and could these flaws in the laws be more important than the laws themselves and it also opens up the possibility that maybe these laws can change with space or time and so we can start looking for evidence of the laws may not be absolute but may undergo some some variation and we can again imagine two types of variation a systematic variation or an arbitrary is or a chaotic variation and now these are very unfashionable points of view but I think that the notion that the laws are absolutely fixed and infinitely precise because it's untestable is one that we should approach with a lot of caution well it is testable in the one senses it could be falsified that's right you can guess you can never prove it right but but you can't falsify that if for example if we show in the early universe the fine-structure constant the ratio of areas of fundamental of forces and laws and physics has changed for some reason hard to do but that would be very significant and there are hints from astronomical observations that maybe some of these basic constants of physics are not actually constant but have undergone a little ditches and things over time but I like to give a very striking example of where I think this belief in infinitely precise laws clearly comes unstuck and it's an example that is drawn from the realm of quantum computation now the in quantum mechanics you could have a curious property called the entanglement Einstein called in ghostly action at a distance and what it means is you could have two particles that may be physically separated but they're entangled in a way that means that if you do something to to this particle that particle knows about it in some sense you can't use its end information or signal fast on the light or anything like that but there's a linkage between the two now the significant thing here is that the more particles you add to this entanglement the more complex this system becomes and it turns out that if you have just four hundred entangled particles the complexity of that system is so great that you could not specify the state of the system even if you used every atom in the universe to represent a particular number there is no way that within the resources of the universe the informational resources of the universe you could even say what that state is it's just 400 entangled particles now you might say well will anybody ever produce a state with 400 integra particles well the answer is in the quantum computation industry where there try to harness the complexity of these states to do computing they set their sights on ten thousands entangled particles in the foreseeable future so this is not totally unreasonable that we're going to hit a real cosmic limit in the informational fidelity or computational capacity of the universe within a few years and we'll see a breakdown in this in these laws because if you believe that quantum mechanics is going to continue to apply according to the present set of rules to a system with more than 400 example particles it means that mother nature isn't computing in the in the real universe mother nature is computing in this platonic realm outside of the universe so it's a real test that we could find in the foreseeable future in one sense all the particles in the universe are entangled in some way right so if we think of the entire universe as a gigantic quantum computer but the significant thing is that the when we talk about bits of information anything that you and I can observe are not these qubits is quantum bits not this entanglement we see real classical bits and so there's a huge reduction that takes place whenever you perform a measurement or observation in quantum mechanics between this vast complex system with always many branches of the wavefunction as we would say so you're describing 400 entangled particles it has ten to the hundred and twenty to ten to the power 125 it's wavefunction to describe it and that's more than there are bits of information and the entire observable universe but when we make an observation this collapses down to two bits of information so the we never actually see these quantum bits but if you believe and this is the key point if you believe that there is a sort of hidden Platonic reality manipulating all these branches of the wave if that's mother nature of work then you have to be a play to this but what are the implications if indeed the constants of physics are changing well if the constants of physics are changing in a systematic manner you can always say well there's a deeper law of physics that describes how they change and so you're you're back to square one but if they're changing in a in a random or chaotic or an arbitrary manner then it would suggest to me that these are flaws in the laws rather than some sort of underlying super law but it's a law or a limitation on the precision of the law well if it's changing in just an arbitrary way I would expect it to be changing throughout time you see the evidence from the the astronomical observations for the so-called fine structure constant suggests that it went through a sort of glitch about 6 billion years ago where as what I'm talking about is a fasteners of the laws it starts out quite great so if we could glimpse what was going on at the time of inflation just after the Big Bang we'd see that there was very considerable fuzziness and that it sort of focuses in overtime so this arbitraries gets reduced as the informational capacity of the universe grows now where it is most significant is of course in the very early universe that's where there's the greatest amount of flexibility or looseness in these laws and very difficult airport for us to observe but it's not inconceivable that this fuzziness in these laws will have left an imprint on the early universe which is observable bias today and indeed the very process of inflation itself which involves exponential expansion already involves numbers which are in excess of the total information content of the universe at the time and so there's a self-consistency argument that I think can be used to test these ideas that we should find that there are remnants or relics in the universe from this very early time when the laws were less precise than they are now what are the implications if the laws of physics are imprecise as you said well I think the implications are that we can if you're the real deep philosophical implications are that it opens the way to a universe which can explain itself and explain its own laws because if the universe comes with a fixed set of laws infinitely precise right from the word go then why the laws are as they are is is a mystery you've got to feel something outside the universe to explain it but if the laws have got some flexibility then we open up the possibility of a feedback loop between the processes going on in the universe and the laws that give rise to them so we're the traditional relationship between laws and states of the universe is a very lopsided one the laws fixed an absolute but the states of the world can change with time and however violent the physical processes that occur in the universe the laws matter not one jot you can't change them at all so the states of the world depend on the laws where the laws are completely independent of the states that's another theological position that comes from monotheistic theology that the universe depends for its existence utterly upon God that God depends not at all on what goes on in the universe and so once you get to the notion that the laws are flexible and the states of the world are flexible then there the symmetry between them has been restored and you have the possibility of a mutual explanation but the laws explain the states in the way that the states explain the laws do you have a self-consistent explanatory new without need for anything external to that whether it's multi universes or whether it's God that's right we don't need to to say well it's a mystery and so all these men or something outside the universe but we don't know what it is

Channel: Closer To Truth

Views: 11,473

Rating: 4.902041 out of 5

Keywords: Paul Davies, Closer To Truth, Nature, Physics, Universe, Cosmology

Id: Puh4PGTvrNw

Length: 12min 47sec (767 seconds)

Published: Thu Jan 28 2016