Do you think Hoffman’s theories about reality and perception are true?

I’ve written about this twice before in some detail, but this was a question on Quora, I addressed last year. I include it here because it’s succinct yet provides specific, robust arguments in the negative.
 
There is a temptation to consider Hoffman a charlatan, but I think that’s a bit harsh and probably not true. The point is that he either knows what he’s arguing is virtually indefensible yet perseveres simply out of notoriety, or he really believes what he’s saying. I’m willing to give him the benefit of the doubt. I think he’s gone so far down this rabbit-hole and invested so much of his time and reputation that it would take a severe cognitive dissonance to even consider he could be wrong. And this goes for a lot of us, in many different fields. In a completely different context, just look at those who have been Trump acolytes turned critics.
 
Below is my response to the question:
 
One-word answer, No. From the very first, when I read an academic paper he co-wrote with Chetan Kaprash, titled Objects of Consciousness (Frontiers in Psychology, 17 June 2014), I have found it very difficult to take him seriously. And everything I’ve read and seen since, only makes me more sceptical.

Hoffman’s ideas are consistent with the belief that we live in a computer simulation, though he’s never made that claim. Nevertheless, his go-to analogy for ‘objects’ we consider to be ‘real’ is the desktop icons on your computer. He talks about the ‘spacetime perceptual interface of H. Sapiens’ as a direct reference to a computer desktop, but it only exists in our minds. In fact, what he describes is what one would experience if one were to use a VR headset. But there is another everyday occurrence where we experience this phenomenon and it’s known as dreaming. Dreams are totally solipsistic, and you’ll notice they often defy reality without us giving them a second thought – until we wake up.

So, how do you know you’re not in a dream? Well, for one, we have no common collective memories with anyone we meet. Secondly, interactions and experiences we have in a dream, that would kill us in real life, don’t. Have you ever fallen from a great height in a dream? I have, many times.

And this is the main contention I have with Hoffman: reality can kill you. He readily admitted in a YouTube video that he wouldn’t step in front of a moving train. He tells us to take the train "seriously but not literally", after all it’s only a desktop icon. But, in his own words, if you put a desktop icon in the desktop bin it will have ‘consequences’. So, walking in front of a moving train is akin to putting the desktop icon of yourself in the bin. A good metaphor perhaps, but hardly a scientifically viable explanation of why you would die.

There are so many arguments one can use against Hoffman, that it’s hard to know where to start, or stop. His most outrageous claim is that ‘space and time doesn’t exist unperceived’, which means that all of history, including cosmological history only exists in the mind. Therefore, not only could we have not evolved, but neither could the planets, solar system and galaxies. In fact, the light we see from distant galaxies, not to mention the CMBR (the earliest observable event in the Universe), doesn’t exist unless someone’s looking at it.

Finally, you can set up a camera to take an image of an object (like a wild cat at night) without any conscious object in sight, except maybe the creature it took a photo of. But then, how did the camera only exist when the animal who didn’t see it, created it with its own consciousness?
 

Addendum:

Following my publishing this post, I watched a later, quite recent video by Hoffman where he gives further reasons for his beliefs. In particular, he states that physics has shown that space and time are no longer fundamental, which is quite a claim. He cites the work of Nima Arkani-Hamed who has used a mathematical object called amplituhedrons to accurately predict the amplitudes of gluons in particle physics. I’ve read about this before in a book by Graham Farmelo (The Universe Speaks in Numbers; How Modern Maths Reveals Nature’s Deepest Secrets). Farmelo tells us that Arkani-Hamed is an American born Iranian, at the Princeton Institute for Advanced Study. To quote Arkani-Hamed directly from Farmelo's book:
 
This is a concrete example of a way in which the physics we normally associate with space-time and quantum mechanics arises from something more basic.
 
And this appears to be the point that Hoffman has latched onto, which he’s extrapolated to say that space and time are not fundamental. Whereas I drew a slightly different conclusion. In my discussion of Farmelo’s book, I made the following point:


The ‘something more basic’ is only known mathematically, as opposed to physically. I found this a most compelling tale and a history lesson in how mathematics appears to be intrinsically linked to the minutia of atomic physics.
 
I followed this with another reference to Arkani-Hamed.



In the same context, Arkani-Hamed says that ‘the mathematics of whole numbers in scattering-amplitude theory chimes… with the ancient Greeks' dream: to connect all nature with whole numbers.’
 
But, as I pointed out both here and in my last post, mathematical abstractions providing descriptions of natural phenomena are not in themselves physical. I see them as a code that allows us to fathom nature’s deepest secrets, which I believe Arkani-Hamed has contributed to.
 
Hoffman’s most salient point is that we need to go beyond time and space to find something more fundamental. In effect, he’s saying we need to go outside the Universe, and he might even be right, but that doesn’t eliminate the pertinent, empirically based and widely held belief that space and time are arguably the most fundamental parameters within the Universe. If he’s saying that consciousness possibly exists beyond, therefore outside, the Universe, I won’t argue with that, because we actually don’t know.
 
Hoffman has created mathematical models of consciousness, which I admit I haven’t read or seen, and he argues that those mathematical models lead to the same mathematical objects (abstractions) that Arkani-Hamed and others have used to describe fundamental physics. Therefore, consciousness creates the objects that the mathematics describes. That’s a very long bow to draw, to use a well-worn euphemism.
 

What does physics really tell us about reality?

 A little while ago I got into another discussion with Mark John Fernee (see previous post), but this time dealing with the relationship between ontology and epistemology as determined by physics. It came about in reference to a paper in Physics Today that someone cited, by N. David Nermin, a retired Professor of physics in Ithaca, New York, titled What’s bad about this habit. In particular, he talked about our tendency to ‘reify’ mathematically determined theories into reality. It helps if we have some definitions, which Fernee conveniently provided that were both succinct and precise.

Epistemology - concerning knowledge.

Ontology - concerning reality.

Reify - to think of an idea as real.

It so happens that around the same time I read an article in New Scientist (25 Mar 2024, pp.32-5) Strange but true? by philosopher, Eric Schwitzgebel, which covers similar territory. The title tells you little, but it’s really about how modern theories in physics don’t really tell us what reality is; instead giving us a range of possibilities to choose from.

I will start with Nermin, who spends the first page talking about quantum mechanics (QM), as it’s the most obvious candidate for a mathematical theory that gets reified by almost everyone who encounters it. This selected quote gives a good feel for what he’s talking about.

When I was a graduate student learning quantum field theory, I had a friend who was enchanted by the revelation that quantum fields were the real stuff that makes up the world. He reified quantum fields. But I hope you will agree that you are not a continuous field of operators on an infinite-dimensional Hilbert space. Nor, for that matter, is the page you are reading or the chair you are sitting in. Quantum fields are useful mathematical tools. They enable us to calculate things.

I found another quote by Freeman Dyson (2014), who makes a similar point to Nermin about the wave function (Ψ).

Unfortunately, people writing about quantum mechanics often use the phrase "collapse of the wave-function" to describe what happens when an object is observed. This phrase gives a misleading idea that the wave-function itself is a physical object. A physical object can collapse when it bumps into an obstacle. But a wave-function cannot be a physical object. A wave-function is a description of a probability, and a probability is a statement of ignorance. Ignorance is not a physical object, and neither is a wave-function. When new knowledge displaces ignorance, the wave-function does not collapse; it merely becomes irrelevant.

But Nermin goes on to challenge even the reality of space and time. Arguing that it is a mathematical abstraction. 

What about spacetime itself? Is that real? Spacetime is a (3+1) dimensional mathematical continuum. Even if you are a mathematical Platonist, I would urge you to consider that this continuum is nothing more than an extremely effective way to represent relations between distinct events.

He then goes on to explain that ‘an event… can be represented as a mathematical point in spacetime.’

He elaborates how this has become so reified into ordinary language that we’re no longer aware that it is an abstraction.

So spacetime is an abstract four-dimensional mathematical continuum of points that approximately represent phenomena whose spatial and temporal extension we find it useful or necessary to ignore. The device of spacetime has been so powerful that we often reify that abstract bookkeeping structure, saying that we inhabit a world that is such a four (or, for some of us, ten) dimensional continuum. The reification of abstract time and space is built into the very languages we speak, making it easy to miss the intellectual sleight of hand.

And this is where I start to have issues with his overall thesis, whereas Fernee said, ‘I completely concur with what he has written, and it is well articulated.’ 

When I challenged Fernee specifically on Nermin’s points about space-time, Fernee argued:

His contention was that even events in space-time are an abstraction. We all assume the existence of an objective reality, and I don't know of anyone who would seriously challenge that idea. Yet our descriptions are abstractions. All we ask of them is that they are consistent, describe the observed phenomena, and can be used to make predictions.

I would make an interesting observation on this very point, that distinguishes an AI’s apparent perspective of space and time compared to ours. Even using the word, ‘apparent’, infers there is a difference that we don’t think about.

I’ve made the point in other posts, including one on Kant, that we create a model of space and time in our heads which we use to interact with the physical space and time that exists outside our heads, and so do all living creatures with eyes, ears and touch. In fact, the model is so realistic that we think it is the external reality.

When we throw or catch a ball on the sporting field, we know that our brains don’t work out the quadratic equations that determine where it’s going to land. But imagine an AI controlled artillery device, which would make those calculations and use a 3-dimensional grid to determine where its ordinance was going to hit. Likewise, imagine an AI controlled drone using GPS co-ordinates – in other words, a mathematical abstraction of space and time – to navigate its way to a target. And that demonstrates the fundamental difference that I think Nermin is trying to delineate. The point is that from our perspective, there is no difference.

This quote gives a clearer description of Nermin’s philosophical point of view.

Space and time and spacetime are not properties of the world we live in but concepts we have invented to help us organize classical events. Notions like dimension or interval, or curvature or geodesics, are properties not of the world we live in but of the abstract geometric constructions we have invented to help us organize events. As Einstein once again put it, “Space and time are modes by which we think, not conditions under which we live.”

Whereas I’d argue that they are both, and the mathematics tells us things about the ‘properties of the world [universe]’ which we can’t directly perceive with our senses – like ‘geodesics’ and the ‘curvature’ of spacetime. Yet they can be measured as well as calculated, which is why we know GR (Einstein’s general theory of relativity) works.

My approach to understanding physics, which may be misguided and would definitely be the wrong approach according to Nermin and Fernee, is to try and visualise the concepts that the maths describes. The concept of a geodesic is a good example. I’ve elaborated on this in another post, but I can remember doing Newtonian-based physics in high school, where gravity made no sense to me. I couldn’t understand why the force of gravity seemed to be self-adjusting so that the acceleration (g) was the same for all objects, irrespective of their mass.

It was only many years later, when I understood the concept of a geodesic using the principle of least action, that it all made sense. The objects don’t experience a force per se, but travel along the path of least action which is also the path of maximum relativistic time. (I’ve described this phenomenon elsewhere.) The point is that, in GR, mass is not in the equations (unlike Newton’s mathematical representation) and the force we all experience is from whatever it is that stops us falling, which could be a chair you’re sitting on or the Earth.

So, the abstract ‘geodesic’ explains what Newton couldn’t, even though Newton gave us the right answers for most purposes.

And this leads me to extend the discussion to include the New Scientist article. The author, Eric Schwitzgebel, ponders 3 areas of scientific inquiry: quantum mechanics (are there many worlds?); consciousness (is it innate in all matter?) and computer simulations (do we live in one?). I’ll address them in reverse order, because that’s easiest.

As Paul Davies pointed out in The Goldilocks Enigma, the so-called computer-simulation hypothesis is a variant on Intelligent Design. If you don’t believe in ID, you shouldn’t believe that the universe is a computer simulation, because some entity had to design it and produce the code.

'Is consciousness innate?' is the same as pansychism, as Schwitzgebel concurs, and I’d say there is no evidence for it, so not worth arguing about. Basically, I don’t want to waste time on these 2 questions, and, to be fair, Schwitzgebel’s not saying he’s an advocate for either of them.

Which brings me to QM, and that’s relevant. Schwitzbegel makes the point that all the scientific interpretations have bizarre or non-common-sensical qualities, of which MWI (many worlds interpretation) is just one. It’s relevance to this discussion is that they are all reifications that are independent of the mathematics, because the mathematics doesn’t discern between them. And this gets to the nub of the issue for me. Most physicists would agree that physics, in a nutshell, is about creating mathematical models that are then tested by experimentation and observation, often using extremely high-tech, not-to-mention behemoth instruments, like the LHC and the James Webb telescope.

It needs to be pointed out that, without exception, all these mathematical models have limitations and, historically, some have led us astray. The most obvious being Ptolemy’s model of the solar system involving epicycles. String theory, with its 10 dimensions and 10^500 possible universes, is a potential modern-day contender, but we don’t really know.

Nevertheless, as I explained with my brief discourse on geodesics (above), there are occasions when the mathematics provides an insight we would otherwise be ignorant of.

Basically, I think what Schwitzgebel is really touching on is the boundary between philosophy and science, which I believe has always existed and is an essential dynamic, despite the fact that many scientists are dismissive of its role.

Returning to Nermin, it’s worth quoting his final passage.

Quantum mechanics has brought home to us the necessity of separating that irreducibly real experience from the remarkable, beautiful, and highly abstract super-structure we have found to tie it all together.

The ‘real experience’ includes the flow of time; the universality of now which requires memory for us to know it exists; the subjective experience of free will. All of these are considered ‘illusions’ by many scientists, not least Sabine Hossenfelder in her excellent book, Existential Physics. I tend to agree with another physicist, Richard Muller, that what this tells us is that there is a problem with our theories and not our reality.

In an attempt to reify QM with reality, I like the notion proposed by Freeman Dyson that it’s a mathematical model that describes the future. As he points out, it gives us probabilities, and it provides a logical reason why Feynman’s abstraction of an infinite number of ‘paths’ are never observed.

Curiously, Fernee provides tacit support for the idea that the so-called ‘measurement’ or ‘observation’ provides an ‘abstract’ distinction between past and future in physics, though he doesn’t use those specific words.

In quantum mechanics, the measurement hypothesis, which includes the collapse of the wave function, is an irreversible process. As we perceive the world through measurements, time will naturally seem irreversible to us.

Very similar to something Davies said in another context:

The very act of measurement breaks the time symmetry of quantum mechanics in a process sometimes described as the collapse of the wave function…. the rewind button is destroyed as soon as that measurement is made.

Lastly, I would like to mention magnetism, because, according to SR, it’s mathematically dependent on a moving electric charge. Only it’s not always, as this video explicates. You can get a magnetic field from electric spin, which is an abstraction, as no one suggests that electrons do physically spin, even though they produce measurable magnetic moments.

What most people don’t know is that our most common experience of a magnetic field, which is a bar magnet, is created purely by electron spin and not moving electrons.

Is randomness real or illusion?

 Let’s look at quantum mechanics (QM). I watched a YouTube video on Closer To Truth with Fred Alan Wolf, a theoretical physicist, whom I admit I’d never heard of. It’s worth watching the first 7 mins before he goes off on a speculative tangent that maybe dreams are a more fundamental level of reality, citing Australian Aboriginal ‘dreamtime’ mythology, of which I have some familiarity, though no scholarship.
 
In the first 7 mins he describes QM: its conceptual frustrations juxtaposed with its phenomenal successes. He gives a good synopsis, explaining how it describes a world we don’t actually experience, yet apparently underpins (my term, not his) the one we do. In particular, he explains:
 
There is a simple operation that takes you out of that space into (hits the table with his hand) this space. And that operation is simply multiplying what that stuff - that funny stuff – is, by itself (waves his hands in circles) in a time-reverse manner, called psi star psi (Ψ*Ψ) in the language of quantum physics.
 
What he’s describing is called the Born rule, which gives probabilities of finding that ‘stuff’ in the real world. By ‘real world’ I mean the one we are all familiar with and that he can hit his hand with. Ψ (pronounced sy) is of course the wave function in Schrodinger’s eponymous equation, and Schrodinger himself wrote a paper (in 1941) demonstrating that Born’s rule effectively multiplies the wave function by itself running backwards in time.
 
Now, some physicists argue that Ψ is just a convenient mathematical fiction and Carlo Rovelli went so far as to argue that it has led us astray (in one of his popular books). Personally, I think it describes the future, which explains why we never see it, or as soon as we try to, it disappears, and if we’re lucky, we get a particle or some other interaction, like a dot on a screen, all of which exist in our past. Note that everything we observe, including our own reflection in a mirror, exists in the past.
 
Wolf then goes on to speculate that the infinite possibilities we use for our calculations are perhaps the true reality. In his own words: What I’m interested in are the things we can’t see… And he makes an interesting point that most people don’t know: that if we don’t take into account the things we can’t see, ‘we get the wrong answers’.
 
And this is where it gets interesting, because he’s alluding to Feynman’s sum-over-histories methodology, which takes into account all the infinite paths that the particle (as wave function) can take. In fact, the more paths that are allowed for, the more accurate the calculation. Wolf doesn’t mention Feynman, but I’m sure that’s what he’s referring to.
 
Feynman’s key insight into QM was that it obeys the least-action principle, which is mathematically expressed as a Lagrangian. It’s the ‘least-action principle’ that determines where light goes through a change in medium (like glass), obeying Fermat’s law where it takes the path of ‘least time’. It also determines the path a ball follows if you throw it into the air by following the path of ‘maximum relativistic time’. I elaborate on this in another post.
 
There is something teleological about this principle, as if the ball, particle, light, ‘knows’ where it has to go. Freeman Dyson, who was a close collaborator with Feynman, argued that QM cannot describe the past, but only the future, and that only classical physics describes the past. So these infinitude of paths that are part of the calculation to determine the probability of where it will actually be ‘observed’ make more sense to me if they exist in the future. I don’t think we need a ‘dream state’ unless that’s a euphemism for the future.
 
Like Dyson, I don’t think we need consciousness to make a quantum phenomenon become real, but it does provide the reference point. In his own words:
 
We do not need a human observer to make quantum mechanics work. All we need is a point of reference, to separate past from future, to separate what has happened from what may happen, to separate facts from probabilities.
 
The thing about consciousness is that it exists in a ‘constant present’, as pointed out by Schrodinger himself (when he wasn’t talking about QM), so it logically correlates with 'a point of reference, to separate past from future', that Dyson refers to.
 
Schrodinger coined a term, ‘statistico-deterministic’, to describe quantum phenomena, because, at a statistical level, it can be very predictable, otherwise we wouldn’t be able to call it ‘successful’. He gives the example of radioactive decay (exploited in his eponymous cat thought experiment) whereby we can’t determine the decay of a single isotope, yet we can statistically determine the half-life of astronomical numbers of atoms very accurately, as everyone knows.
 
I contend that real randomness, that we all observe and are familiar with, is caused by chaos, but even this is a contentious idea. I like to give the example of tossing a coin, but a lot of physicists will tell you that tossing a coin is not random. In fact, I recently had a lengthy, but respectful, discourse with Mark John Fernee (physicist at Qld Uni) on Quora on this very topic. When I raised the specific issue of whether tossing a coin is ‘random’, he effectively argued that there are no random phenomena in physics. To quote him out of context:
 
Probability theory is built from statistical sampling. There is no assumed underlying physics.
 
The underlying physics can be deterministic, while a statistical distribution of events can indicate random behaviour. This is the assumption that is applied to every coin toss. Because this is just an assumption, you can cheat the system by using specific conditions that ensure deterministic outcomes.
 
What I am saying is that randomness is a statistical characterisation of outcomes that does not include any physical mechanism. As such, it is not a fundamental property of nature. (Emphasis in original)
 
I get the impression from what I’ve read that mathematicians have a different take on chaos to physicists, because they point out that you need to calculate initial conditions to infinite decimal places to achieve a 100% predicted outcome. Physicist, Paul Davies, provided a worked example in his 1988 book, The Cosmic Blueprint. I quoted Davies to Fernee during our ‘written’ conversation:
 
It is actually possible to prove that the activity of the jumping particle is every bit as random as tossing a coin.
 
The ‘jumping particle’ Davies referred to was an algorithm using clock arithmetic, that when graphed produced chaotic results, and he demonstrated that it would take a calculation to infinity to get it ‘exactly right’. Fernee was dismissive of this and gave it as an example of a popular science book leading laypeople (like myself) astray, which I thought was a bit harsh, as Davies actually goes into the mathematics in some detail, and I possibly misled Fernee by quoting just one sentence.
 
Just to be clear, Fernee doesn’t disagree that chaotic phenomena are impossible to predict; just that they are fully deterministic and, in his words, only ‘indicate random behaviour’.
 
Sabine Hossenfelder, who argues very strongly for superdeterminism, has a video demonstrating how predicting chaotic phenomena (like the weather) has a horizon (my term, not hers) of predictability that can never be exceeded, even in principle (10 days in the case of the weather).
 
So Fernee and Hossenfelder distinguish between what we ‘cannot know’ and what physically transpires. But my point is that chaotic phenomena, if rerun, will always produce a different result – it’s built into the mathematics underlying the activity – and includes significant life-changing phenomena like evolutionary biology and the orbits of the planets, as well as weather and earthquakes. Even the creation of the moon is believed to be a consequence of a chaotic event, without which life on Earth would never have evolved.
 
Note that both QM and chaos have mathematical underpinnings, and whilst most see that as modelling or a very convenient method of making predictions, I see it as more fundamental. I contend that mathematics transcends the Universe, yet it’s also a code that allows us to plumb Nature’s deepest secrets and fathom the dynamics of the Universe on all scales.

 

Follow-up (30 Mar 2024)

Following my discourse with Fernee, I reread Davies’ book, The Cosmic Blueprint (for the third time since I bought it in the late 80s), or at least the part that was relevant. I really did Davies a disservice by just quoting one sentence out of context. In fact, Davies goes to a lot of trouble to try and define what randomness means. He also acknowledges that, despite being totally unpredictable, chaotic phenomena are still ‘deterministic’ – it’s just the initial conditions that are unattainable (mathematically as well as physically). That is why, when you rerun a chaotic event, you get a different result, despite being so-called ‘deterministic’.
 
As well as the mathematical example I gave above, Davies discusses in detail 2 physical systems that are chaotic – the population of certain species of animals and the forcing of a pendulum (where a constant force is applied to a pendulum at a different frequency to its natural frequency). Marcus du Sautoy in his book, What We Cannot Know, interviews ex-pat Australian, Robert May (now a Member of the House of Lords), who did pioneering work on chaos theory in animal populations.
 
Davies quotes Ilya Prigogine concerning ‘…the conviction that the future is determined by the present…  We may perhaps even call it the founding myth of classical science.’
 
He also quotes Joseph Ford: ‘…the fact that determinism actually reigns only over a quite finite domain; outside this small haven of order lies a largely uncharted, vast wasteland of chaos where determinism has faded into an ephemeral memory of existence theorems and only randomness survives.’
 
And then Davies himself:
 
But in reality, our universe is not a linear Newtonian mechanical system; it is a chaotic system… No finite intelligence, however powerful, could anticipate what new forms or systems may come to exist in the future, The universe is in some sense open; it cannot be known what new levels of variety or complexity may be in store.
 
In light of these comments from last century, and considering that under Newton and Pascale, everyone thought that given enough information, the entire universe’s future could be foreseen, I see ‘strong determinism’ (as opposed to weak determinism) as a scientific ‘fashion’ that’s come back into favour. By ‘weak determinism’, I mean that all physical phenomena have a causal relationship; it’s just impossible to predict beyond a horizon, which is dependent on the nature of the phenomenon (whether it be the weather or the planets). Therefore, I think randomness is built into the Universe, and its principal mechanism is chaos, not quantum.

Does simultaneity have any meaning?

 Someone on Quora asked me a question about simultaneity with respect to Einstein’s special theory of relativity (SR), so I referenced a 30min video of a lecture on the subject, which I’ve cited before on this blog. It not only provides a qualitative explanation or description, but also provides the calculations which demonstrate the subjectivity of simultaneity as seen by different observers.
 
Below I’ve copied exactly what I posted on Quora, including the imbedded video. I’ll truncate the question to make things simpler. The questioner (Piet Venter) asked if there is experimental evidence, which I ignored, partly because I don’t know if there is, but also because it’s mathematically well understood and it’s a logical consequence of SR. Afterwards, I’ll discuss the philosophical ramifications.
 
Does the train embankment thought experiment of Einstein really demonstrate relativity of simultaneity?
 
Actually, there’s a very good YouTube video, which explains this much better than I can. It’s a lecture on the special theory of relativity (SR) and you might find the mathematics a bit daunting, but it’s worth persevering with. He gives the perspective from both a ‘stationary’ observer and a ‘moving’ observer. Note that he also allows for space-contraction for the ‘moving’ case to arrive at the correct answer.

 
To be specific, he uses the Bob and Alice scenario with Bob in a spaceship, so Bob’s ‘stationary’ with respect to the light signals, while he’s ‘moving’ with respect to Alice. What I find interesting is that from Bob’s perspective, he sees what I call a ‘true simultaneity’ (though no one uses that term) because everything is in the same frame of reference for Bob. The lecturer explains both their perspectives qualitatively in the first 6 mins, before he gets into the calculations.
 
When he does the calculations, Bob sees no difference in the signals, while Alice does. This infers that Bob has a special status as an observer compared to Alice. This is consistent with the calculations if you watch the whole video. The other point that no one mentions, is that Alice can tell that the signal on Bob’s ship is moving with respect to her reference-frame because of the Doppler shift of the light, whereas Bob sees no Doppler shift.

 
I commit a heresy by talking about a ‘true simultaneity’, while physicists will tell you there’s no such thing. But even the lecturer in the video makes the point that, according to Bob, he sees the two events recorded by his ‘clocks’ as happening at the same time, because everything is stationary in his frame of reference. Even though his frame of reference is moving relative to others, including Alice, and also compared to anyone on Earth, presumably (since he’s in a spaceship).
 
I contend that Bob has a special status and this is reflected in the mathematics. So is this a special case or can we generalise this to other events? People will argue that a core tenet of Einstein’s relativity is that there are no observers with a ‘special status’. But actually, the core tenet, as iterated by the lecturer in the video, is that the speed of light is the same for all observers, irrespective of their frame of reference. This means that even if an observer is falling into a black hole at the speed of light, they would still see any radiation travelling at the speed of light relative to them. So relativity creates paradoxes, and I gave a plausible resolution to that particular paradox in a recent post, as did David Finkelstein in 1958. (The ‘special status’ is that Bob is in the same frame of reference, his spaceship, as the light source and the 2 resultant events.)
 
In another even more recent post, I cited Kip Thorne explaining how, when one looks at the curvature of spacetime, one gets the same results if spacetime is flat and it’s the ruler that distorts. If one goes back to the Bob and Alice thought experiment in the video, Alice sees (or measures) a distortion, in as much as the front clock in Bob’s spaceship ‘lags’ his rear clock, where for Bob they are the same. This is because, from Alice’s perspective, the light signal takes longer to reach the front because it’s travelling away from her (from Bob’s perspective, it’s stationary). On the other hand, the rear clock is travelling towards the light signal (from her perspective).
 
When I was first trying to get my head around relativity, I took an unusual and novel approach. Because we are dealing with light waves, it occurred to me that both observers would ‘see’ the same number of waves, but the waves would be longer or shorter, which also determines the time and distance that they measure, because waves have wavelength (corresponding to distance) and frequency (corresponding to time).
 
If I apply this visualisation trick to Alice’s perception, then the waves going to the front clock must get longer and the waves going to the rear must get shorter, if they are to agree with the number of waves that Bob ‘sees’, whereby from his perspective, there’s no change in wavelength or frequency. And if the number of waves correspond to a ‘ruler’, then Alice’s ruler becomes distorted while Bob’s doesn’t. So she ‘measures’ a longer distance to the front from the light source than the rear, and because it takes longer for the light to reach the front clock, then it ‘lags’ (relative to Bob’s recording) according to her observation, using her own clocks (refer video).
 
So, does this mean that there is a universal simultaneity that we can all agree on? No, it doesn’t. For a start, using the thought experiment in the video, Bob is travelling relative to a frame of reference, which is the spacetime of the Universe. In fact, if there is a gravitational gradient in his space ship then that would be enough to put his clocks out of sync, so his frame of reference is idealised.
 
But I would make the point that not all observations of simultaneity are equal. While observers in different locations in the Universe would see the same events happening in different sequences; for events having a causal relationship, then all observers would see the same sequence, irrespective of their frame of reference. Since everything that happens is causally related to past events, then everything exists in a sequence that is unchangeable. It’s just that there is no observer who can see all causal sequences – it’s impossible. This brings me back to Kant, whom I reference in my last post, that there is an epistemological gap between what we can observe and what really is. If there is a hypothetical ‘universal now’ for the entire universe, no single observer within the universe can see it. Current wisdom is that it doesn’t exist, but I contend that, if it does, we can’t know.

What would Kant say?

Even though this is a philosophy blog, my knowledge of Western philosophy is far from comprehensive. I’ve read some of the classic texts, like Aristotle’s Nicomachean Ethics, Descartes Meditations, Hume’s A treatise of Human Nature, Kant’s Critique of Pure Reason; all a long time ago. I’ve read extracts from Plato, as well as Sartre’s Existentialism is a Humanism and Mill’s Utilitarianism. As you can imagine, I only recollect fragments, since I haven’t revisited them in years.
 
Nevertheless, there are a few essays on this blog that go back to the time when I did. One of those is an essay on Kant, which I retitled, Is Kant relevant to the modern world? Not so long ago, I wrote a post that proposed Kant as an unwitting bridge between Plato and modern physics. I say, ‘unwitting’, because, as far as I know, Kant never referenced a connection to Plato, and it’s quite possible that I’m the only person who has. Basically, I contend that the Platonic realm, which is still alive and well in mathematics, is a good candidate for Kant’s transcendental idealism, while acknowledging Kant meant something else. Specifically, Kant argued that time and space, like sensory experiences of colour, taste and sound, only exist in the mind.
 
Here is a good video, which explains Kant’s viewpoint better than me. If you watch it to the end, you’ll find the guy who plays Devil’s advocate to the guy expounding on Kant’s views makes the most compelling arguments (they’re both animated icons).

But there’s a couple of points they don’t make which I do. We ‘sense’ time and space in the same way we sense light, sound and smell to create a model inside our heads that attempts to match the world outside our heads, so we can interact with it without getting killed. In fact, our modelling of time and space is arguably more important than any other aspect of it.
 
I’ve always had a mixed, even contradictory, appreciation of Kant. I consider his insight that we may never know the things-in-themselves to be his greatest contribution to epistemology, and was arguably affirmed by 20th Century physics. Both relativity and quantum mechanics (QM) have demonstrated that what we observe does not necessarily reflect reality. Specifically, different observers can see and even measure different parameters of the same event. This is especially true when relativistic effects come into play.
 
In relativity, different observers not only disagree on time and space durations, but they can’t agree on simultaneity. As the Kant advocate in the video points out, surely this is evidence that space and time only exist in the mind, as Kant originally proposed. The Devil’s advocate resorts to an argument of 'continuity', meaning that without time as a property independent of the mind, objects and phenomena (like a candle burning) couldn’t continue to happen without an observer present.
 
But I would argue that Einstein’s general theory of relativity, which tells us that different observers can measure different durations of space and time (I’ll come back to this later), also tells us that the entire universe requires a framework of space and time for the objects to exist at all. In other words, GR tells us, mathematically, that there is an interdependence between the gravitational field that permeates and determines the motion of objects throughout the entire universe, and the spacetime metric those same objects inhabit. In fact, they are literally on opposite sides of the same equation.
 
And this brings me to the other point that I think is missing in the video’s discussion. Towards the end, the Devil’s advocate introduces ‘the veil of perception’ and argues:
 
We can only perceive the world indirectly; we have no idea what the world is beyond this veil… How can we then theorise about the world beyond our perceptions? …Kant basically claims that things-in-themselves exist but we do not know and cannot know anything about these things-in-themselves… This far-reaching world starts to feel like a fantasy.
 
But every physicist has an answer to this, because 20th Century physics has taken us further into this so-called ‘fantasy’ than Kant could possibly have imagined, even though it appears to be a neverending endeavour. And it’s specifically mathematics that has provided the means, which the 2 Socratic-dialogue icons have ignored. Which is why I contend that it’s mathematical Platonism that has replaced Kant’s transcendental idealism. It’s rendered by the mind yet it models reality better than anything else we have available. It’s the only means we have available to take us behind ‘the veil of perception’ and reveal the things-in-themselves.
 
And this leads me to a related point that was actually the trigger for me writing this in the first place.
 
In my last post, I mentioned I’m currently reading Kip A. Thorne’s book, Black Holes and Time Warps; Einstein’s Outrageous Legacy (1994). It’s an excellent book on many levels, because it not only gives a comprehensive history, involving both Western and Soviet science, it also provides insights and explanations most of us are unfamiliar with.
 
To give an example that’s relevant to this post, Thorne explains how making measurements at the extreme curvature of spacetime near the event horizon of a black hole, gives the exact same answer whether it’s the spacetime that distorts while the ‘rulers’ remain unchanged, or it’s the rulers that change while it’s the spacetime that remains ‘flat’. We can’t tell the difference. And this effectively confirms Kant’s thesis that we can never know the things-in-themselves.
 
To quote Thorne:
 
What is the genuine truth? Is spacetime really flat, or is it really curved? To a physicist like me this is an uninteresting question because it has no physical consequences (my emphasis). Both viewpoints, curved spacetime and flat, give the same predictions for any measurements performed with perfect rulers and clocks… (Earlier he defines ‘perfect rulers and clocks’ as being derived at the atomic scale)
 
Ian Miller (a physicist who used to be active on Quora) once made the point, regarding space-contraction, that it’s the ruler that deforms and not the space. And I’ve made the point myself that a clock can effectively be a ruler, because a clock that runs slower measures a shorter distance for a given velocity, compared to another so-called stationary observer who will measure the same distance as longer. This happens in the twin paradox thought experiment, though it’s rarely mentioned (even by me).

The role of prejudice in scientific progress

 I’m currently reading Black Holes and Time Warps; Einstein’s Outrageous Legacy by Kip A. Thorne, published in 1994. Despite the subject matter, it’s very readable, and virtually gives a history of the topic by someone who was more than just an observer, but a participant.
 
What I find curious is how everyone involved, including Einstein, Oppenheimer and Wheeler, had their own prejudices, some of which were later proven incorrect. None of these great minds were infallible. And one shouldn’t be surprised by this, given they were all working on the very frontier of physics and astrophysics in particular.
 
And surely that means that some of my prejudices will eventually be proven wrong. I expect so, even if I’m not around to acknowledge them. Science works because people’s prejudices can be overturned, which always requires a certain cognitive dissonance. As Freeman Dyson remarked in one his Closer-to-Truth interviews with Robert Lawrence Kuhn, every question answered by science invariably poses more questions, so it’s part of the process.
 
Of course, I’m not even a scientist, but a self-described spectator on the boundary of ideas. So why should I take myself seriously? Because, over time, my ideas have evolved and I’ve occasionally had insights that turned out to be true. One of these was confirmed in the reading of Thorne’s book. In a not-so-recent post, The fabric of the Universe, I attempted to resolve the paradox that an external observer to someone falling into a black hole sees them frozen in time, whereas the infalling subject experiences no such anomaly. I concluded that space itself falls into the black hole at the speed of light.
 
It so happens that a little-known postdoc, David Finkelstein, wrote a paper effectively coming to the same conclusion – only a lot more rigorously – in 1958, when I was still in primary school. The thing is that people like Penrose, Oppenheimer and Wheeler were convinced, though it had stumped them. In fact, according to Thorne, Wheeler took longer to be convinced. Thorne himself wrote an article in Scientific American in 1967, describing it by using diagrams showing a 2-D ‘fabric’ dragging ants into the hole, while they 'rolled balls’ away at the speed-of-light. At the event horizon the balls were exactly the same speed as the fabric, but in the opposite direction. Therefore, to the external observer, they were never ‘received’, but to the ants, the balls were travelling at the speed-of-light relative to them. Paradox solved. Note it was solved more than 60 years before I worked it out for myself.
 
And this is the thing: I need to work things out for myself, which is why I stick to my prejudices until I’m convinced that I’m wrong. But, to be honest, that’s what scientists do (I emphasise, I’m not a scientist) and that’s how science works. I contend that there is a dialectic between science and philosophy, where philosophy addresses questions that science can’t currently answer, but when it does, it asks more questions, so it’s neverending.