The Centenary of Einstein’s General Theory of Relativity

This month (November 2015) marks 100 years since Albert Einstein published his milestone paper on the General Theory of Relativity, which not only eclipsed Newton’s equally revolutionary Theory of Universal Gravitation, but is still the cornerstone of every cosmological theory that has been developed and disseminated since.

It needs to be pointed out that Einstein’s ‘annus mirabilis’ (miraculous year), as it’s been called, occurred 10 years earlier in 1905, when he published 3 groundbreaking papers that elevated him from a patent clerk in Bern to a candidate for the Nobel Prize (eventually realised of course). The 3 papers were his Special Theory of Relativity, his explanation of the photo-electric effect using the newly coined concept, photon of light, and a statistical analysis of Brownian motion, which effectively proved that molecules made of atoms really exist and were not just a convenient theoretical concept.

Given the anniversary, it seemed appropriate that I should write something on the topic, despite my limited knowledge and despite the plethora of books that have been published to recognise the feat. The best I’ve read is The Road to Relativity; The History and Meaning of Einstein’s “The Foundation of General Relativity” (the original title of his paper) by Hanoch Gutfreund and Jurgen Renn. They have managed to include an annotated copy of Einstein’s original handwritten manuscript with a page by page exposition. But more than that, they take us on Einstein’s mental journey and, in particular, how he found the mathematical language to portray the intuitive ideas in his head and yet work within the constraints he believed were necessary for it to work.

The constraints were not inconsiderable and include: the equivalence of inertial and gravitational mass; the conservation of energy and momentum under transformation between frames of reference both in rotational and linear motion; and the ability to reduce his theory mathematically to Newton’s theory when relativistic effects were negligible.

Einstein’s epiphany, that led him down the particular path he took, was the realisation that one experienced no force when one was in free fall, contrary to Newton’s theory and contrary to our belief that gravity is a force. Free fall subjectively feels no different to being in orbit around a planet. The aptly named ‘vomit comet’ is an aeroplane that goes into free fall in order to create the momentary sense of weightlessness that one would experience in space.

Einstein learnt from his study of Maxwell’s equations for electromagnetic radiation, that mathematics could sometimes provide a counter-intuitive insight, like the constant speed of light.

In fact, Einstein had to learn new mathematics (for him) and engaged the help of his close friend, Marcel Grossman, who led him through the technical travails of tensor calculus using Riemann geometry. It would seem, from what I can understand of his mental journey, that it was the mathematics, as much as any other insight, that led Einstein to realise that space-time is curved and not Euclidean as we all generally believe. To quote Gutfreund and Renn:

[Einstein] realised that the four-dimensional spacetime of general relativity no longer fitted the framework of Euclidean geometry… The geometrization of general relativity and the understanding of gravity as being due to the curvature of spacetime is a result of the further development and not a presupposition of Einstein’s formulation of the theory.

By Euclidean, one means space is flat and light travels in perfectly straight lines. One of the confirmations of Einstein’s theory was that he predicted that light passing close to the Sun would be literally bent and so a star in the background would appear to shift as the Sun approached the same line of sight for an observer on Earth as for the star. This could only be seen during an eclipse and was duly observed by Arthur Eddington in 1919 on the island of Principe near Africa.

Einstein’s formulations led him to postulate that it’s the geometry of space that gives us gravity and the geometry, which is curved, is caused by massive objects. In other words, it’s mass that curves space and it’s the curvature of space that causes mass to move, as John Wheeler famously and succinctly expounded.

It may sound back-to-front, but, for me, Einstein’s Special Theory of Relativity only makes sense in the context of his General Theory, even though they were formulated in the reverse order. To understand what I’m talking about, I need to explain geodesics.

When you fly long distance on a plane, the path projected onto a flat map looks curved. You may have noticed this when they show the path on a screen in the cabin while you’re in flight. The point is that when you fly long distance you are travelling over a curved surface, because, obviously, the Earth is a sphere, and the shortest distance between 2 points (cities) lies on what’s called a great circle. A great circle is the one circle that goes through both points that is the largest circle possible. Now, I know that sounds paradoxical, but the largest circle provides the shortest distance over the surface (we are not talking about tunnels) that one can travel and there is only one, therefore there is one shortest path. This shortest path is called the geodesic that connects those 2 points.

A geodesic in gravitation is the shortest distance in spacetime between 2 points and that is what one follows when one is in free fall. At the risk of information overload, I’m going to introduce another concept which is essential for understanding the physics of a geodesic in gravity.

One of the most fundamental principles discovered in physics is the principle of least action (formulated mathematically as a Lagrangian which is the difference between kinetic and potential  energy). The most commonly experienced example would be refraction of light through glass or water, because light travels at different velocities in air, water and glass (slower through glass or water than air). The extremely gifted 17th Century amateur mathematician, Pierre de Fermat (actually a lawyer) conjectured that the light travels the shortest path, meaning it takes the least time, and the refractive index (Snell’s law) can be deduced mathematically from this principle. In the 20th Century, Richard Feynman developed his path integral method of quantum mechanics from the least action principle, and, in effect, confirmed Fermat’s principle.

Now, when one applies the principle of least action to a projectile in a gravitational field (like a thrown ball) one finds that it too takes the shortest path, but paradoxically this is the path of longest relativistic time (not unlike the paradox of the largest circle described earlier).

Richard Feynman gives a worked example in his excellent book, Six Not-So-Easy Pieces. In relativity, time can be subjective, so that a moving clock always appears to be running slow compared to a stationary clock, but, because motion is relative, the perception is reversed for the other clock. However, as Feynman points out:

The time measured by a moving clock is called its “proper time”. In free fall, the trajectory makes the proper time of an object a maximum.

In other words, the geodesic is the trajectory or path of longest relativistic time. Any variant from the geodesic will result in the clock’s proper time being shorter, which means time literally slows down. So special relativity is not symmetrical in a gravitational field and there is a gravitational field everywhere in space. As Gutfreund and Renn point out, Einstein himself acknowledged that he had effectively replaced the fictional aether with gravity.

This is most apparent when one considers a black hole. Every massive body has an escape velocity which is the velocity a projectile must achieve to become free of a body’s gravitational field. Obviously, the escape velocity for Earth is larger than the escape velocity for the moon and considerably less than the escape velocity of the Sun. Not so obvious, although logical from what we know, the escape velocity is independent of the projectile’s mass and therefore also applies to light (photons). We know that all body’s fall at exactly the same rate in a gravitational field. In other words, a geodesic applies equally to all bodies irrespective of their mass. In the case of a black hole, the escape velocity exceeds the speed of light, and, in fact, becomes the speed of light at its event horizon. At the event horizon time stops for an external observer because the light is red-shifted to infinity. One of the consequences of Einstein’s theory is that clocks travel slower in a stronger gravitational field, and, at the event horizon, gravity is so strong the clock stops.

To appreciate why clocks slow down and rods become shorter (in the direction of motion), with respect to an observer, one must understand the consequences of the speed of light being constant. If light is a wave then the equation for a wave is very fundamental:

v = f λ , where v is velocity, f is the frequency and λ is the wavelength.

In the case of light the equation becomes c = f λ , where c is the speed of light.

One can see that if c stays constant then f and λ can change to accommodate it. Frequency measures time and wavelength measures distance. One can see how frequency can become stretched or compressed by motion if c remains constant, depending whether an observer is travelling away from a source of radiation or towards it. This is called the Doppler effect, and on a cosmic scale it tells us that the Universe is expanding, because virtually all galaxies in all directions are travelling away from us. If a geodesic is the path of maximum proper time, we have a reference for determining relativistic effects, and we can use the Doppler effect to determine if a light source is moving relative to an observer, even though the speed of light is always c.

I won’t go into it here, but the famous twin paradox can be explained by taking into account both relativistic and Doppler effects for both parties – the one travelling and the one left at home.

This is an exposition I wrote on the twin paradox.

The Unreasonable Effectiveness of Mathematics

I originally called this post: Two miracles that are fundamental to the Universe and our place in it. The miracles I’m referring to will not be found in any scripture and God is not a necessary participant, with the emphasis on necessary. I am one of those rare dabblers in philosophy who argues that science is neutral on the subject of God. A definition of miracle is required, so for the purpose of this discussion, I call a miracle something that can’t be explained, yet has profound and far-reaching consequences. ‘Something’, in this context, could be described as a concordance of unexpected relationships in completely different realms.

This is one of those posts that will upset people on both sides of the religious divide, I’m sure, but it’s been rattling around in my head ever since I re-read Eugene P. Wigner’s seminal essay, The Unreasonable Effectiveness of Mathematics in the Natural Sciences. I came across it (again) in a collection of essays under the collective title, Math Angst, contained in a volume called The World Treasury of Physics, Astronomy and Mathematics edited by Timothy Ferris (1991). This is a collection of essays and excerpts by some of the greatest minds in physics, mathematics and cosmology in the 20th Century.

Back to Wigner, in discussing the significance of complex numbers in quantum mechanics, specifically Hilbert’s space, he remarks:

‘…complex numbers are far from natural or simple and they cannot be suggested by physical observations. Furthermore, the use of complex numbers in this case is not a calculated trick of applied mathematics but comes close to being a necessity in the formulation of the laws of quantum mechanics.’

It is well known, among physicists, that in the language of mathematics, quantum mechanics not only makes perfect sense but is one of the most successful physical theories ever. But in ordinary language it is hard to make sense of it in any way that ordinary people would comprehend it.

It is in this context that Wigner makes the following statement in the next paragraph following the quote above:

‘It is difficult to avoid the impression that a miracle confronts us here… or the two miracles of the existence of laws of nature and of the human mind’s capacity to divine them.’

Hence the 2 miracles I refer to in my introduction. The key that links the 2 miracles is mathematics. A number of physicists: Paul Davies, Roger Penrose, John Barrow (they’re just the ones I’ve read); have commented on the inordinate correspondence we find between mathematics and regularities found in natural phenomena that have been dubbed ‘laws of nature’.

The first miracle is that mathematics seems to underpin everything we know and learn about the Universe, including ourselves. As Barrow has pointed out, mathematics allows us to predict the makeup of fundamental elements in the first 3 minutes of the Universe. It provides us with the field equations of Einstein’s general theory of relativity, Maxwell’s equations for electromagnetic radiation, Schrodinger’s wave function in quantum mechanics and the four digit software code for all biological life we call DNA.

The second miracle is that the human mind is uniquely evolved to access mathematics to an extraordinarily deep and meaningful degree that has nothing to do with our everyday prosaic survival but everything to do with our ability to comprehend the Universe in all the facets I listed above.

The 2 miracles combined give us the greatest mystery of the Universe, which I’ve stated many times on this blog: It created the means to understand itself, through us.

So where does God fit into this? Interestingly, I would argue that when it comes to mathematics, God has no choice. Einstein once asked the rhetorical question, in correspondence with his friend, Paul Ehrenfest (if I recall it correctly): did God have any choice in determining the laws of the Universe? This question is probably unanswerable, but when it comes to mathematics, I would answer in the negative. If one looks at prime numbers (there are other examples, but primes are fundamental) it’s self-evident that they are self-selected by their very definition – God didn’t choose them.

The interesting thing about primes is that they are the ‘atoms’ of mathematics because all the other ‘natural’ numbers can be determined from all the primes, all the way to infinity. The other interesting thing is that Riemann’s hypothesis indicates that primes have a deep and unexpected relationship with some of the most esoteric areas of mathematics. So, if one was a religious person, one might suggest that this is surely the handiwork of God, yet God can’t even affect the fundamentals upon which all this rests.

Addendum: I changed the title to reflect the title of Wigner's essay, for web-search purposes.

Freedom; a moral imperative

I wrote something about freedom recently, in answer to a question posed in Philosophy Now (Issue 108, Jun/Jul 2015) regarding What's The More Important: Freedom, Justice, Happiness, Truth? My sequence of importance starting at the top was Truth, Justice, Freedom and Happiness based on the argued premise that each was dependent on its predecessor. But this post is about something else: the relevance of John Stuart Mill’s arguments on ‘liberty’ in the 21st Century.

Once again, this has been triggered by Philosophy Now, but Issue 110 (Oct/Nov 2015) though the context is quite different. Philosophy Now is a periodical and they always have a theme, and the theme for this issue is ‘Liberty & Equality’ so it’s not surprising to find articles on freedom. In particular, there are 2 articles: Mill, Liberty & Euthanasia by Simon Clarke and The Paradox of Liberalism by Francisco Mejia Uribe.

I haven’t read Mill’s book, On Liberty, which is cited in both of the aforementioned articles, but I’ve read his book, Utilitarianism, and what struck me was that he was a man ahead of his time. Not only is utilitarian philosophy effectively the default position in Western democracies (at least, in theory) but he seemed to predict findings in social psychology like the fact that one’s conscience is a product of social norms and not God whispering in one’s ear, and that social norms can be changed, like attitudes towards smoking, for example. I’ve written a post on utilitarian moral philosophy elsewhere, so I won’t dwell on it here.

The first essay by Clarke (cited above) deals with the apparent conflict between freedom to pursue one’s potential and the freedom to end one’s life through euthanasia, which is not the subject of this post either. It’s Clarke’s reference to Mill’s fundamental philosophy of individual freedom that struck a chord with me.

An objectively good life, on Mill’s (Aristotelian) view, is one where a person has reached her potential, realizing the powers and abilities she possesses. According to Mill, the chief essential requirement for personal well-being is the development of individuality. By this he meant the development of a person’s unique powers, abilities, and talents, to their fullest potential.

I’ve long believed that the ideal society allows this type of individualism: that each of us has the opportunity, through education, mentoring and talent-driven programmes to pursue the goals best suited to our abilities. Unfortunately, the world is not an equitable place and many people - the vast majority - don’t have this opportunity.

The second essay (cited above), by Uribe, deals with the paradox that arises when liberal political and societal ideals meet fundamentalism. One may ask: what paradox? The paradox is that liberal attitudes towards freedom of expression, religious and cultural norms allows the rise of fundamentalist ideals that actually wish to curtail such freedoms. In the current age, fundamentalism is associated with Islamic fundamentalism manifested by various ideologies all over the globe, which has led to a backlash in the form of Islamophobia. Some, like IS (Islamic State) and Boko Haram (in Nigeria) have extreme, intolerant views that they enforce on entire populations in the most brutal and violent manner imaginable. In other words, they could not be further from Mill’s ideal of freedom and liberation (Uribe, by the way, makes no reference to Islam).

In Western societies, there is a widely held fear, exploited by many right-winged and nationalist movements, that Islamic fundamentalism will overthrow our Western democratic systems of government and replace it with a religious totalitarian one. The reports of extreme human rights violations (including genocide, slavery and internet posted executions) in far-off politically unstable countries, only adds to this paranoia.

There are caveats to Mill’s manifesto (my term) on individual freedom, as pointed out by Clarke: ‘Excepting children and the insane, for whom intervention for their own sake is permissible…’ and ‘Freedom for the sake of individuality does not allow the harming of others, because that would damage the individuality of others.’

It’s this last point: ‘that would damage the individuality of others’; that I would argue, goes to the crux of the issue. Totalitarianism and fundamentalist ideologies should and can be opposed on this moral principle – political and social structures that inhibit unfairly the ability for individuals to pursue happiness should not be supported. This seems self-evident, yet it’s at the core of the current gay-marriage debate that is happening in many Western countries, including Australia (where I live). It’s also the reason that many Muslims oppose Islam extremists as they affect their own individualism.

On another, freedom-related issue, Australia has for the past 15 years pursued a ruthless, not-to-mention contentious, policy of so-called ‘border protection’ against refugees arriving by boat. Both sides of the political spectrum in Australia pursue this policy because our politics have become almost completely poll-driven, and any change of policy by either side, would immediately damage them in the polls, due to the paranoid nature of our society at large. This is related to the issue of Islamophobia I mentioned earlier, because a large portion of these refugees are from the unstable countries where atrocities are being committed. Not surprisingly, it’s the right-wing elements who exploit this issue as well. But it’s hard to imagine an issue that more strongly evokes Mill’s demand for individual freedom and liberty (except, possibly, the abolition of slavery).

As I said in an earlier post (the one I reference above), freedom and hope are partners. It’s the deliberate elimination of hope that drives my government’s policy, and the fact that this has serious mental health consequences is not surprising, yet it’s ignored.

Imprisonment is the most widely employed method of punishment for criminals because it eliminates freedom, though not necessarily hope. The Australian government’s rationalisation behind their extremely tough policy on asylum seekers is that they are ‘illegals’ and therefore deserve to be punished in this manner. However, the punishment is much worse than what we dispense to convicted criminals under our justice system. It’s a sad indictment on our society that we have neither the political will nor the moral courage to reverse this situation.

What is now?

Notice I ask what and not when, because ‘now’, as we experience it, is the most ephemeral of all experiences. As I’ve explained in another post: to record anything at all requires a duration – there is no instantaneous moment in time – except in mathematical calculus where a sleight-of-hand makes an infinitesimal disappear completely. It’s one of the most deceptive tricks in mathematics, but in mathematics you can have points with zero dimensions in space, so time with zero dimensions is just another idealism that allows one to perform calculations that would otherwise be impossible.

But another consequence of ‘now’ is that without memory we would not even know we have consciousness. Think about it: ‘now’ has no duration and consciousness exists in a continuous present so no memory would mean no experience of consciousness, or ‘now’ for that matter, because once it occurs it’s already in the past. Therefore memory is required to experience it at all.

But this post is not about calculus or consciousness per se; it arose from a quote I came across attributed to William Lawrence Bragg:

Everything that has already happened is particles, everything in the future is waves. The advancing sieve of time coagulates waves into particles at the moment ‘now’.

For those who don’t know, Sir William Lawrence Bragg was son of Sir William Henry Bragg, whom, as far as I know, were the only father and son to be jointly awarded a Nobel Prize in physics, for their work on X-ray diffraction in crystals. Henry was born in England and Lawrence was born in Australia. I heard about them at school, naturally, but I only came across this quote earlier in the week. They were among the first to exploit short wave photons (X-rays) to find the atomic-scale dimensions of crystal lattices, thus pioneering the discipline of crystallography.

In the same week, I came across this quote from Freeman Dyson recalling a conversation he had with Richard Feynman:

Thirty-one years ago Dick Feynman told me about his ‘sum over histories’ version of quantum mechanics. ‘The electron does anything it likes’, he said. ‘It goes in any direction at any speed, forward and backward in time, however it likes, and then you add up the amplitudes and it gives you the wave-function.’ I said, ‘You’re crazy.’ But he wasn’t.

I’ve discussed in some detail the mathematical formulation of the ‘wave-function’ known as Schrodinger’s equation, in another post, but what’s significant, in regard to the 2 quotes I’ve cited, is that the wave function effectively disappears or becomes irrelevant once an ‘observation’ or experimental ‘measurement’ occurs. In other words, the wave function ‘permeates all space’ (according to Richard Elwes in MATHS 1001) before it becomes part of the ‘classical physics’ real world. So Bragg’s quote makes perfect sense that the wave function represents the future and the particle ‘observation’, be it a photon or electron or whatever, represents the past with the interface being ‘now’.

As I’ve explicated in my last post, the default interpretation of Feyman’s ‘sum over histories’ or ‘path integrals’ mathematical description of quantum mechanics, is that all ‘histories’ occur in parallel universes, but I would argue that it’s a consequence of the irreversibility of time once the particle is ‘observed’. Now ‘observed’, in this context, means that the particle becomes part of the real world, or at least, that’s my prosaic interpretation. There is an extreme interpretation that it does require a ‘conscious observation’ in order to become real, but the fact that the Universe existed many billions of years prior to consciousness evolving, makes this interpretation logically implausible to say the least.

Brian Cox, in one of his BBC TV programmes (on ‘Time’) points out that one of the problems that Einstein had with quantum mechanics is that, according to its ‘rules’, the future was indeterminate. Einstein’s mathematical formulation of space-time, which became fundamental to his General Theory of Relativity (albeit was a consequence of his Special Theory) was that time could literally be treated like a dimension of space. This meant that the future was just as ‘real’ as the past. In other words, Einstein firmly believed that the universe, and therefore our lives, are completely deterministic – there was no place for free will in Einstein’s universe. Interestingly, this was a topic in a not-so-recent issue of Philosophy Now, though the author of the article didn’t explain that Einstein’s strict position on this was a logical consequence of his interpretation of space-time: the future was just as fixed as the past.

But, even without quantum mechanics, we know that chaos theory also contributes to the irreversibility of time, although Einstein was unaware of chaos theory in his lifetime. Paul Davies explains this better than most in his book on chaos theory, The Cosmic Blueprint.

The point is that, both in chaos theory and Feynman’s multiple histories, there are many possibilities that can happen in the ‘future’, but the ‘past’ is only one path and it can’t be remade. According to David Deutsch and Max Tegmark, all the future possibilities occur both in quantum mechanics and at a macro level. In fact, Deutsch has argued that chaotic phenomena are a consequence of the quantum mechanics' many worlds interpretation. In effect, they disassemble the asymmetry between the future and the past. According to their world-view, the future is just as inevitable as the past, because no matter which path is chosen, they all become reality somewhere in some universe; all of which bar one, we can’t see. From my perspective, this is not an argument in support of the many worlds interpretation, but an argument against it.

In my last post but one, I discussed at length Paul Davies’ book, The Mind of God. One of his more significant insights was that the Universe allows evolvement without dictating its end. In other words, it’s because of both chaos and quantum phenomena that there are many possible outcomes yet they all arise from a fixed past and this is a continuing process - it’s deterministic yet unpredictable.

One could make the same argument for free will. At many points in our lives we make choices based on a past that is fixed whilst conscious of a future that has many possibilities. I agree with Carlo Rovelli that free will is not a consequence of quantum mechanics, but the irreversibility of time applies to us as individual conscious agents in exactly the same way it applies to the dynamics of the Universe at both quantum and macro levels.

There is just one problem with this interpretation of the world, and that is, according to Einstein’s theories, there is no universal ‘now’. If there is no simultaneity, which is a fundamental outcome of the Special Theory of Relativity, then it’s difficult to imagine that people separated in space-time could agree on a ‘now’. And yet, the fact that we give the Universe an age and a timeline, effectively insists that there must be a ‘now’ for the Universe at large. I confess I don’t know enough physics to answer this, but quantum entanglement reintroduces simultaneity by stealth, even if we can’t use it to send messages. One of the features of the Universe is causality. Despite the implications of both quantum mechanics and relativity theory on the physics of time, neither of them interfere with causality, despite what some may argue (and that includes entanglement). But causality requires the speed of light to separate causal events, which is why the ‘now’ we experience sees stars in the firmament up to billions of years old. So space-time makes ‘now’ a subjective experience, even to the extent that at the event horizon of a black hole ‘now’ can become frozen to an outside observer.

Addendum: I actually believe there is a universal 'now', which I've addressed in a later post (towards the end).

Are Multiverses the solution or the problem?

Notice I use the plural for something that represents a collection of universes. That’s because there are multiple versions of them; according to Max Tegmark there are 3 levels of multiverses.

I’m about to do something that I criticise others for doing: I’m going to challenge the collective wisdom of those who are much smarter and more knowledgeable than me. I’m not a physicist, let alone a cosmologist, and I’m not an academic in any field – I’m just a blogger. My only credentials are that I read a lot, especially about physics by authors who are eminently qualified in their fields. But even that does not give me any genuine qualification for what I’m about to say. Nevertheless, I feel compelled to point out something that few others are willing to cognise.

This occurred to me after I wrote my last post. In the 2 books I reference by Paul Davies (The Mind of God and The Goldilocks Enigma) he discusses and effectively dismisses the multiverse paradigm, yet I don’t mention it. Partly, that was because the post was getting too lengthy as it was, and, partly, because I didn’t need to discuss it to make the point I wished to make.

But the truth is that the multiverse is by far the most popular paradigm in both quantum physics and cosmology, and this is a relatively recent trend. What I find interesting is that it has become the default position, epistemologically, to explain what we don’t know at both of the extreme ends of physics: quantum mechanics and the cosmos.

Davies makes the point, in Mind of God (and he’s not the only one to do so), that for many scientists there seems to be a choice between accepting the multiverse or accepting some higher metaphysical explanation that many people call God. In other words, it’s a default position in cosmology because it avoids trying to explain why our universe is so special for life to emerge. Basically, it’s not special if there are an infinite number of them.

In quantum mechanics, the multiverse (or many words interpretation, as it’s called) has become the most favoured interpretation following the so-called Copenhagen interpretation championed by Niels Bohr. It’s based on the assumption that the wave function, which describes a quantum particle in Hilbert space doesn’t disappear when someone observes something or takes a measurement, but continues on in a parallel universe. So a bifurcation occurs for every electron and every photon every time it hits something. What’s more, Max Tegmark argues that if you have a car crash and die, in another universe you will continue to live. And likewise, if you have a near miss (as he did, apparently) in this universe, then in another parallel universe you died.

In both cases, cosmology and quantum mechanics, the multiverse has become the ‘easy’ explanation for events or phenomena that we don’t really understand. Basically, they are signposts for the boundaries or limits of scientific knowledge as it currently stands. String Theory or M Theory, is the most favoured cosmological model, but not only does it predict 10 spatial dimensions (as a minimum, I believe) it also predicts 10⁵⁰⁰ universes.

Now, I’m sure many will say that since the multiverse crops up in so many different places: caused by cosmological inflation, caused by string theory, caused by quantum mechanics; at least one of these multiverses must exist, right? Well no, they don’t have to exist – they’re just speculative, albeit consistent with everything we currently know about this universe, the one we actually live in.

Science, as best I understand it, historically, has always homed in on things. In particle physics it homed in on electrons, protons and neutrons, then neutrinos and quarks in all their varieties. In biology, we had evolution by natural selection then we discovered genes and then DNA, which underpinned it all. In mechanics, we had Galileo, Kepler and Newton, who finally gave us an equation for gravity, then Einstein gave us relativity theory that equated energy with mass in the most famous equation in the world, plus the curvature of space-time giving a completely geometric account of gravity that also provided a theoretical foundation for cosmology. Faraday, followed by Maxwell showed us that electricity and magnetism are inherently related and again Einstein took it further and gave an explanation of the photo-electric effect by proposing that light came in photons.

What I’m trying to say is that we made advances in science by either finding more specific events and therefore particles or by finding common elements that tied together apparently different phenomena. Kepler found the mathematical formulation that told us that planets travel in ellipses, Newton told us that gravity’s inverse square law made this possible and Einstein told us that it’s the curvature of space-time that explains gravity. Darwin and Wallace gave us a theory of evolution by natural selection, but Mendel gave us genes that explained how the inheritance happened and Francis and Crick and Franklin gave us the DNA helix that is the key ingredient for all of life.

My point is that the multiverse explanation for virtually everything we don’t know is going in the opposite direction. Now the explanation for something happening, whether it be a quantum event or the entire universe, is that every possible variation or physical manifestation is happening but we can only see the one we are witnessing. I don’t see this as an explanation for anything; I only see it as a manifestation of our ignorance.


Addendum: This is Max Tegmark providing a very cogent counterargument to mine. I think his argument from inflation is the most valid and his argument from QM multiple worlds, the most unlikely. Quantum computers won't prove parallel universes, because they are dependent on entanglement (as I understand it) which is not the same thing as multiple copies. Philip Ball makes this exact point in Beyond Weird, where he explains that so-called multiple particles only exist as probabilities; only one of which becomes 'real'.

Physics, mathematics, the Universe - is Reason its raison d'être?

I’ve just read Paul Davies’ The Mind of God: Science & The Search for Ultimate Meaning, published in 1992, so a couple of decades old now. He wrote this as a follow-up to God and the New Physics, which I read some years ago. This book is more philosophical and tends to deal with cosmology and the laws of physics – it’s as much about epistemology and the history of science as about the science itself. Despite its age, it’s still very relevant, especially in regard to the relationship between science and religion and science and mathematics, both of which he discusses in some depth.

Davies is currently at The University of Arizona (along with Lawrence Krauss, who wrote A Universe from Nothing, amongst others), but at the time he wrote The Mind of God, Davies was living and working in Australia, where he wrote a number of books over a couple of decades. He was born and educated in England, so he’s lived on 3 continents.

Davies is often quoted out of context by Christian fundamentalists, giving the impression that he supports their views, but anyone who reads his books knows that’s far from the truth. When he first arrived in America, he was sometimes criticised on blogs for ‘promoting his own version of religion’, usually by people who had heard of him but never actually read him. From my experience of reading on the internet, religion is a sensitive topic in America on both sides of the religious divide, so unless your views are black or white you can be criticised by both sides. It’s worth noting that I’ve heard or read Richard Dawkins reference Davies on more than a few occasions, always with respect, even though Davies is not atheistic.

Davies declares his philosophical position very early on, which is definitely at odds with the generally held scientific point of view regarding where we stand in the scheme of things:

I belong to the group of scientists who do not subscribe to a conventional religion but nevertheless deny that the universe is a purposeless accident… I have come to the point of view that mind – i.e., conscious awareness of the world – is not a meaningless and incidental quirk of nature, but an absolute fundamental facet of reality. That is not to say that we are the purpose for which the universe exists. Far from it. I do, however, believe that we human beings are built into the scheme of things in a very basic way.

In a fashion, this is a formulation of the Strong Anthropic Principle, which most scientists, I expect, would eschew, but it’s one that I find appealing, much for the same reasons given by Davies. The Universe is such a complex phenomenon, its evolvement (thus far) culminating in the emergence of an intelligence able to fathom its own secrets at extreme scales of magnitude in both space and time. I’ve alluded to this ‘mystery’ in previous posts, so Davies’ philosophy appeals to me personally, and his book, in part, attempts to tackle this very topic.

Amongst other things, he gives a potted history of science from the ancients (especially the Greeks, but other cultures as well) and how it has largely replaced religion as the means to understand natural phenomena at all levels. This has resulted in a ‘God-of-the-Gaps’, where, epistemologically, scientific investigations and discoveries have gradually pushed God out of the picture. He also discusses the implications of a God existing outside of space and time actually creating a ‘beginning’. The idea of a God setting everything in motion (via the Big Bang) and then watching his creation evolve over billions of years like a wound up watch (Davies’ analogy) is no more appealing than the idea of a God who has to make adjustments or rewind it occasionally, to extend the metaphor.

In discussing how the scientific enterprise evolved, in particular how we search for the cause of events, reminded me of my own attraction to science from a very early age. Children are forever asking ‘why’ and ‘how’ questions – we have a natural inclination to wonder how things work – and by the time I’d reached my teens, I’d realised that science was the best means to pursue this.

Davies gives an example of Newton coming up with mathematical laws to explain gravity that not only provided a method to calculate projectiles on Earth but also the orbits of planets in the solar system. Brian Cox in a documentary on Gravity, wrote the equation down on a piece of paper, borrowing a pen from his cameraman, to demonstrate how simple it is. But Newton couldn’t explain why everything didn’t simply collapse in on itself and evoked God as the explanation for keeping the clockwork universe functioning. So Newton’s explanation of gravity, albeit a work of genius, didn’t go far enough.

Einstein then came up with his theory that gravity was a consequence of the curvature of space-time caused by mass, but, as Cox points out in his documentary, Einstein’s explanation doesn’t go far enough either, and there are still aspects of gravity we don’t understand, at the quantum level and in black holes where the laws of physics as we know them break down. As an aside, it’s the centenary year of Einstein publishing his General Theory of Relativity and I’ve just finished reading a book (The Road to Relativity by Hanoch Gutfreund and Jurgen Renn) which goes through the original manuscript page by page explaining Einstein’s creative process.

But back to Newton’s theory, I remember, in high school, trying to understand why acceleration in a gravitational field was the same irrespective of the mass of the body, and I could only resort to the mathematics to give me an answer, which didn’t seem satisfactory. I can also remember watching a light plane in flight over our house and seeing it side-slipping in the wind. In other words, the direction of the nose was slightly offset to its direction of travel to counter a side wind. I remember imagining the vectors at play and realising that I could work them out with basic trigonometry. It made me wonder for the first time, why did mathematics provide an answer and an explanation – what was the link between mathematics, a product of the mind, and a mechanical event, a consequence of the physical world?

I’ve written quite a lot on the topic of mathematics and its relationship to the laws of nature; Davies goes into this in some depth. It is worth quoting him on the subject, especially in regard to the often stated scepticism that the laws of nature only exist in our minds.

Sometimes it is argued that laws of nature, which are attempts to capture [nature’s] regularities systematically, are imposed on the world by our minds in order to make sense of it… I believe any suggestion that the laws of nature are similar projections of the human mind [to seeing animals in the constellations, for example] is absurd. The existence of regularities in nature are a mathematical objective fact… Without this assumption that the regularities are real, science is reduced to a meaningless charade.

He adds the caveat that the laws as written are ‘human inventions, but inventions designed to reflect, albeit imperfectly, actually existing properties of nature.’ Every scientist knows that our rendition of nature’s laws have inherent limitations, despite their accuracy and success, but quite often they provide new insights that we didn’t expect. Well known examples are Maxwell’s equations predicting electromagnetic waves and the constant speed of light, and Dirac’s equation predicting anti-matter. Most famously, Einstein’s special theory of relativity predicted the equivalence of energy and mass, which was demonstrated with the detonation of the atomic bomb. All these predictions were an unexpected consequence of the mathematics.

Referring back to Gutfreund’s and Renn’s book on Einstein’s search for a theory of gravity that went beyond Newton but was consistent with Newton, Einstein knew he had to find a mathematical description that not only fulfilled all his criteria regarding relativistic space-time and the equivalence of inertial and gravitational mass, but would also provide testable predictions like the bending of light near massive stellar objects (stars) and the precession of mercury’s orbit around the sun. We all know that Riemann’s non-Euclidian geometry gave him the mathematical formulation he needed and it’s been extraordinarily successful thus far, despite the limitations I mentioned earlier.

Davies covers quite a lot in his discussion on mathematics, including a very good exposition on Godel’s Incompleteness Theorem, Turing’s proof of infinite incomputable numbers, John Conway’s game of life with cellular automata and Von Neuman’s detailed investigation of self-replicating machines, which effectively foreshadowed the mechanics of biological life before DNA was discovered.

In the middle of all this, Davies makes an extraordinary claim, based on reasoning by Oxford mathematical physicist David Deutsch (the most vocal advocate for the many worlds interpretation of quantum mechanics and a leader in quantum computer development). Effectively, Deutsch argues that mathematics works in the real world (including electronic calculators and computers) not because of logic but because the physical world (via the laws of physics) is amenable to basic arithmetic: addition, subtraction etc. In other words, he’s basically saying that we only have mathematics because there are objects in our world that we can count. In effect, this is exactly what Davies says.

This is not the extraordinary claim. The extraordinary claim is that there may exist universes where mathematics, as we know it, doesn’t work, because there are no discrete objects. Davies extrapolates this to say that a problem that is incomputable with our mathematics may be computable with alternative mathematics that, I assume, is not based on counting. I have to confess I have issues with this.

To start from scratch, mathematics starts with numbers, which we all become acquainted with from an early age by counting objects. It’s a small step to get addition from counting but quite a large step to then abstract it from the real world, so the numbers only exist in our heads. Multiplication is simply adding something a number of times and subtraction is simply taking away something that was added so you get back to where you started. The same is true for division where you divide something you multiplied to go backwards in your calculation. In other words, subtraction and division are just the reverse operations for addition and multiplication respectively. Then you replace some of the numbers by letters as ‘unknowns’ and you suddenly have algebra. Now you’re doing mathematics.

The point I’d make, in reference to Davies’ claim, is that mathematics without numbers is not mathematics. And numbers may be to a different base or use different symbols, but they will all produce the same mathematics. I agree with Deutsch that mathematics is intrinsic to our world – none of us would do mathematics if it wasn’t. But I find the notion that there could hypothetically exist worlds where mathematics is not relevant or is not dependent on number, absurd, to use one of Davies’ favourite utterances.

Earlier in the book, Davies expresses scepticism at the idea that the laws of nature could arise with the universe – that they didn’t exist beforehand. In other words, he’s effectively arguing that they are transcendent. Since the laws are firmly based in mathematics, it’s hard to argue that the laws are transcendent but the mathematics is not.

I have enormous respect for Davies, and I wonder if I’m misrepresenting him. But this is what he said, albeit out of context:

Imagine a world in which the laws of physics were very different, possibly so different that discreet objects did not exist. Some of the mathematical operations that are computable in our world would not be so in this world, and vice versa.

Speaking of mathematical transcendence, he devotes almost an entire chapter to the underlying mystery of mathematics’ role in explicating natural phenomena through physics, with particular reference to mathematical Platonists like Kurt Godel, Eugene Wigner and Roger Penrose. But it’s a quote from Richard Feynman, who was not a Platonist as far as I know, that sums up the theme.

When you discover these things, you get the feeling that they were true before you found them. So you get the idea that somehow they existed somewhere… Well, in the case of physics we have double trouble. We come across these mathematical interrelationships but they apply to the universe, so the problem of where they are is doubly confusing… Those are philosophical questions that I don’t know how to answer.

Interestingly, in his later book, The Goldilocks Enigma (2006), Davies distances himself from mathematical Platonism and seems to espouse John Wheeler’s view that both the mathematics and the laws of nature emerged ‘higgledy-piggledy’ and are not transcendent. He also tackles the inherent conflict between the Strong Anthropic Principle, which he seems to support, and a non-teleological universe, which science virtually demands, but I’ll address that later.

Back to The Mind of God, he discusses in depth one of the paradigms of our age that the Universe can be totally understood by algorithms leading to the possibility that the Universe we live in is a Matrix-like computer simulation. Again, referring to The Goldilocks Enigma, he discounts this view as a variation on Intelligent Design. Towards the end of Mind of God, he discusses metaphysical, even mystical possibilities, but not as a replacement for science.

But one interesting point he makes, that I’ve never heard of before, was proposed by James Hartle and Murray Gellmann, who claim:

…that the existence of an approximately classical world, in which well-defined material objects exist in space, and in which there is a well-defined concept of time, requires special cosmic initial conditions.

In other words, they’re saying that the Universe would be a purely quantum world with everything in superpositional states (nothing would be fixed in space and time) were it not for ‘the special quantum state in which the universe originated.’ James Hartle developed with Stephen Hawking the Hawking-Hartle model of the Universe where time evolved out of a 4th dimension in a quantum big bang. It may be that Hartle’s and Gellmann’s conjecture is dependent on the veracity of that particular model. The link between the two ideas is only alluded to by Davies.

Apropos to the book’s title, Davies spends an entire chapter on ‘God’ arguments, in particular cosmological and ontological arguments that require a level of philosophical nous that, frankly, I don’t possess. Having said that, it became obvious to me that arguments for God are more dependent on subjective ‘feelings’ than rational requirements. After lengthy discussions on ‘necessary being’ and a ‘contingent universe’, and the tension if not outright contradiction the two ideas pose, Davies pretty well sums up the situation with this:

What seems to come through such analyses loud and clear is the fundamental incompatibility of a completely timeless, unchanging, necessary God with the notion of creativity in nature, with a universe that can change and evolve and bring forth the genuinely new…

In light of this, the only ‘God’ that makes sense to me is one that evolves like ‘Its’ creation and, in effect, is a consequence of it rather than its progenitor.

One of the points that Davies makes is how the Universe is not strictly deterministic or teleological, yet it allows for self-organisation and the evolvement of complexity; in essence, a freedom of evolvement without dictating it. I would call this pseudo-teleological and is completely consistent with both quantum and chaotic events, which dominate all natural phenomena from cosmological origins to the biological evolution of life.

This brings one back to the quote from Davies at the beginning of this discussion that the universe is not a meaningless accident. Inherent in the idea of meaningfulness is the necessary emergence of consciousness and its role as the prime source of reason. If not for reason the Universe would have no cognisance of its own existence and it would be truly ‘purposeless’ in every way. It is for this reason that people believe in God, in whatever guise they find him (or her, as the case may be). Because we can find reason in living our lives and use reason to understand the Universe, the idea that the Universe itself has no reason is difficult to reconcile.