Could time-travel subvert Fermi’s paradox?

It’s a little tongue-in-cheek, but I don’t find it totally out-of-the-question either. This post is a confluence of a few things, only two of which are mentioned in the title.

The best exposition of Fermi’s paradox I’ve come across, is by Prof Brian Cox. In fact, he provides a very good succinct definition in the first 2m of his video.

 

Notwithstanding the fact that there has been billions of years on billions of worlds for civilisations to arise, we see no evidence of any of them in the Galaxy at all. So the paradox is, Why?

 

He then uses the remaining 20+ minutes of the video, providing expositions on various reasons why this is the case. Firstly, he gives a history lesson, explaining how life on Earth took close to 4 billion years to evolve to its present state. He doesn’t mention that humans (homo sapiens) only arose in the last 3-400,000 years of that, so the last 0.01% or thereabouts, and it’s only in the last century of that 300k+ years that we developed very rudimentary extra-terrestrial space exploration capabilities (my point, not his). So a blink-of-an-eye in the context of our evolutionary history.

 

He goes on to give various scenarios why the Fermi paradox exists but the one most pertinent to this post (around 7m) is that the distance between worlds that could have the same properties as our solar system, in being able to create a stable environment over tens of billions of years for life to evolve, are at least thousands of lightyears away (in our galaxy), and therefore beyond the ability to travel here in the timeframe that such distances dictate. He points out that even the time required for receiving radio transmissions are commensurate with the distance to be traversed. Which is why searching for ‘artificial’ signals is the most efficient method to look for extra-terrestrial civilisations.

 

One of his best arguments involves Von Neumann machines or ‘replicators’, which are self-replicating robots, which could colonise a galaxy within 100s of millions of years (his estimate). He contends that the fact we’ve never seen any, is the best indicator we have that a spacefaring civilisation doesn’t exist in our galaxy.

 

I won’t elaborate on any of the other scenarios Cox expounds upon, but I recommend watching the full 23m, because it’s very stimulating and informative. He also talks about the ‘Great Filter’ (~10m), which is a scary yet totally plausible scenario, although not relevant to this post. Basically, he says that civilisations like us, who can create the technology for space-travel, also have the technology to destroy ourselves, and may lack the wisdom to do one over the other. In his own words, we’re brought undone by our ‘stupidity’.

 

His best argument he left to last, which I’ve reported on before, but based on Nick Lane’s excellent book, Life Ascending; The Ten Great Inventions of Evolution. Basically, Cox argues there was 4B years of life before complex life arose, and it’s such a rare possibility that maybe it’s never happened anywhere else. Note: this doesn’t rule out simple life being prolific throughout the galaxy. He cites John Barrow's and Frank Kipler’s book, The Anthropic Principle, which he explains, he grew up with, as supporting that particular view. I read that book and reference it here.

 

That took longer than I intended, so now I will address the other part of my question, which is time-travel. Another physicist, Jim Al-Khalili, who wrote an excellent book called Paradox (which I’ve read) has a video titled provocatively, Could I Travel Back in Time? where he explores various time-travel scenarios.

 

Naturally, he starts with the well known grandfather paradox, whereby you travel back in time to kill your grandfather before he met your grandmother, thus breaking the causal chain for your own existence. This idea was exploited in the original Terminator movie. In fact, it’s hard to talk about time-travel without referencing science fiction examples.

 

He then uses the scenario of having found instructions to build a time machine, actually builds it, which takes him 10 years, then travels back 10 years in time to drop the instructions on his desk. Al-Khalili points out a couple of issues: it defeats free will because if the scientist ‘chooses’ not to travel back in time, it can’t happen at all; and the instructions are never actually created in the first place, so causality is overturned. He also mentions the problem of having 2 versions of the scientist existing at the same time, therefore breaking the first law of thermodynamics: conservation of energy.

 

He then talks about how travelling into the future is physically possible according to Einstein’s theories of relativity, either by travelling close to the speed of light, as per the famous twin paradox thought experiment, or spending time in a strong gravitational field, as per the movie, Interstellar. A version of the last one, I’ve used in my own science fiction.

 

Al-Khalili draws a spacetime diagram showing the future and past light cones, which features strongly in my way of viewing this. But without getting ahead of myself, he points out that, according to GR (Einstein’s general theory of relativity), if you could curve spacetime strongly enough you could create a time-loop. In fact, this would be a feature of a rotating universe, as pointed out by Einstein’s friend, Kurt Godel, as well as a possibility for a rapidly spinning black hole. There is good reason to believe we don’t live in a rotating universe, but rotating black holes, one assumes, are quite common. Could one get stuck in a time-loop at the event horizon of a spinning black hole? I don’t know.

 

Al-Khalili cites Russian astrophysicist, Igor Novikov, who proposed his own rule, regarding CTCs (Closed-Timelike-Curves): ‘Only “logically self-consistent” solutions are allowed’.

 

Al-Khalili then introduces us to Dr Fabio Costa, who has published a paper where he talks about taking time-slices, where cause-and-effects create boundary conditions, which neither he nor Al-Khalili explain in detail. But Costa concludes by saying, “Nature is smart enough to prevent such paradoxes” (referring to the grandfather paradox, specifically). My takeaway, which admittedly is rather simplistic, even superficial, is that cause-and-effect is such a fundamental principle in physics, that any scenario that sidesteps it, needs to be treated with extreme caution. I should point out that there are scientists and philosophers (like Donald Hoffman) who think that causality, as a principle, is past its use-by date.

 

As Al-Khalili sums up, Fabio Costa argues that “time paradoxes disappear, not because they’re logically inconsistent, but because they’re physically not allowed.”

 

Al-Khalili also refers to the Many Worlds Interpretation (MWI) of quantum mechanics, as providing another loophole, for want of a better expression, to allow time-travel without creating paradoxes. In fact, this is the scenario invoked in the Back to the Future movie franchise. When Marty McFly goes back to the past and intervenes, he subsequently finds himself in a different universe when he returns to the present. Al-Khalili explains how this resolves the grandfather paradox very neatly (similar to the Marty McFly scenario), but like me, he has issues with MWI as a reality.

 

Lastly, Al-Khalili talks to Dr Lorenzo Gavassino at the Department of Mathematics, Vanderbilt University, Nashville, Tennessee, who took a serious look at the Groundhog Day scenario, but proposes that the individual was in a closed box that underwent a time loop. Specifically, he looked at how this is impacted by the 2^nd Law of Thermodynamics or entropy, because when the individual went back in time their entropy would decrease and their memories would be erased. Again, I might be simplifying it for the sake of explication, but it’s what I expect a time loop would create. The way Gavassino describes it, including his literal handwaving, the time loop has 2 nodes, where at one node the entropy is at its lowest and at the other node, entropy is highest. And effectively, the individual oscillates between these two extremes.

 

Right at the end, Al-Khalili makes the point that I’ve heard before, which is that if someone did invent a time machine, it could never go back to earlier than the time it was invented, which is why we’ve never seen one.

 

Again, I spent much longer on this than I intended but I’m now going to reference yet another video that talks about the edge of time for the entire universe. In essence, I’m going to discuss a video by Curt Jaimungal who discusses an aspect of Einstein’s GR that I’d never heard about before. Curt often discusses very esoteric topics, but I’m confident he knows what he’s talking about, because I’ve seen him hold his own with such luminaries as Stephen Wolfram, Gregory Chaitin, Sir Roger Penrose and Sabine Hossenfelder. In fact, I watched a 2hr video conversation he had with her after he sent me a link, and they were very chatty and friendly.

 

I had to watch this more than once to get my head around it, and I’ll rely heavily on quotes to get my points across. As a side-issue, he addresses a conundrum I’ve raised many times before, which is that the Universe has an edge in time, but not space (as best we can tell), yet relativity theory tells us that there is no universal now. I’ll get to that, but first I’ll address what the video is primarily about.

 

What the video is about, contrary to what everyone seems to believe, including Einstein himself, based on what I know, is that his GR equations don’t provide for a deterministic universe at the very limit or edge of the Universe in time. In fact, Curt contends that it is even less deterministic than quantum mechanics with an infinity of possibilities. At one point, he quips, “God does not even play dice, He just shrugs.”

 

But what I want to focus on, is what Curt calls a ‘Cauchy surface,’ which, if I understand him correctly, is the hypersurface that we are all familiar with in the spacetime diagram that Al-Khalili referred to in his video, which also shows the past and future light cones for any observer at time, t.

Significantly, Curt distinguishes between local determinism and global determinism, because he argues that GR allows for one and not the other, and this is also relevant to determining what ‘now’ means. Significantly, global determinism "determines the future of the entire universe", whereas local determinism refers to "what happens in the immediate future of that region [of space]".

 

Curt defines a ‘Cauchy surface’ as “a spacelike slice, that every causal curve hits exactly once.” He emphasises this with beats of his hand for every single word. An obvious consequence of this is that there can be no time loops.

 

He then asks the obvious question: can you extrapolate local determinism to global determinism? His answer is very informative in that he contends that in flat spacetime this is ‘trivial’ because you can, but not in curved spacetime, which is what GR describes. I think this is also relevant in attempting to understand what a universal now means.

 

In fact, Curt says, specifically, “There are solutions to the field equations of Einstein [in GR] where you literally can’t define a moment of time across the entire universe.” He then emphasises the point, by saying: “In general relativity, there may not be a way to slice spacetime in all of space at time t.” Note, this is a consequence of spacetime curvature and not SR (special theory of relativity) as most arguments claim.

 

And there’s a term for this, which is ‘global hyperbolicity’, and that’s where he introduces his definition of a Cauchy surface which I referenced earlier. So the spacelike slice where every ‘causal curve’ only crosses once, applies to the entire universe.

 

Then, in an apparent contradiction to what he told us before, he says “the Cauchy surface is like a snapshot of the universe at one time.” He then emphasises again that “every world line [for a particle] and every light ray; they all cross the surface exactly once.” He then says, “This is what even allows you to say, the state of the Universe at time t.” And I think this is the closest you will get to the idea of a universal now. But there is a caveat, which is that “not all solutions to Einstein’s equations are globally hyperbolic.”

 

He then provides examples which mostly include black holes, including rotating black holes, which I mentioned in reference to Al-Khalili’s video. He also mentions Godel’s rotating universe, which I think we can confidently say, we don’t inhabit.

 

Curt has an understanding of this topic that makes me realise how little I really know. What I do know is that clocks measure time at different rates depending on gravity, so if you happened to live near a black hole, you would measure the age of the Universe as younger than someone on Earth, so you would axiomatically get a different t.

 

What Curt doesn’t describe is the possibility that there is a wavefunction for the entire universe, which some scientists believe (like Sean Carroll, for example), and, if it describes the future, as Freeman Dyson believed, then maybe entanglement provides an edge in time for the entire universe. But I’m speculating way beyond the limits of my knowledge.

 

This post has already become too long with detours down various rabbit holes, but there is one more video I want to reference, which has specific relevance to the title.

 

I grew up in a small rural town in Australia, and I’m old enough to remember when TV arrived, though we didn’t own a set until I was 16. The saving grace for me were books, including both the primary school and high school libraries, which I devoured. So it was around 16 years of age that I read a book called The Truth About Flying Saucers by Aime Michel, first published in 1956 (I looked it up), and I admit to being profoundly influenced by it. (I’m not sure you’d find a book on flying saucers in a modern high school in Australia.) It so happened that I had a science teacher who was also interested in UFOs – he was a very good science teacher, by the way, and I’m not the only one who would say that.

 

I’ve since become more sceptical about the whole UFO scene, as I’ve developed what I believe is a healthy scepticism towards conspiracy theories of any ilk. So it’s in that context that I reference an episode of Australian Story on ABC TV, where a group of people from a small town in Australia recollect a particular ‘incident’ from their childhood, involving phenomena that couldn’t be explained at the time, or even now.

 

When I watched this and listened to their testimony, I thought that one explanation, which is even more out-there than the possibility of visitors from outer space, is the possibility that some ultra-advanced technological species has learned how to travel through time from the future. Perhaps only a sci-fi writer would even consider that.

 

But there is another possibility, which I thought of when I watched Brian Cox’s video. If you look at the spacetime diagram depicting past and future light cones, it’s obvious that most of the events in the so-called ‘observable’ universe are ‘unobservable.’ It’s possible, therefore, that there are civilisations billions of light years away, who have developed technologies that exceed ours, which we can’t possibly know about using radio waves, Von Neumann machines or whatever. Unless, that is, they’ve developed the technology to travel through time as well as space.

 

The thing is that if someone (or some object) was able to visit us from outside our past or future light cones, it wouldn’t create a causal loop, unlike all the examples that Al-Khalili provided in his video (except MWI).

 

My conjecture, if I can call it that, which is admittedly more sci-fi than science reality, is: What if a technologically advanced enough extra-terrestrial species developed the ability to ride the hyperplane on the Cauchy surface, while avoiding black holes, and was able to visit our world line? As Brian Cox said at the end of his video, a scientist has to be able to admit they’re wrong, but it would require a visitor in a flying saucer to convince him.

 

Footnote: The last video I referenced, Australian Story, is very good reporting, and I recommend you watch it so you can make your own judgement.

The Case Against Reality by Donald D. Hoffman

As I’ve pointed out before, YouTube has allowed scientists and philosophers of all stripes to promote pet theories that they know they can’t pursue academically with the same freedom. In fact, I’ve heard comments from people like Gregory Chaitin and Sabine Hossenfelder, who feel that the innate conservatism in academia is hindering progress in research and exploring new ideas.

 

Donald Hoffman is possibly an exception given his credentials: ‘Professor of Cognitive Sciences at the University of California, Irvine… [He] is the author of over one hundred scholarly articles on various aspects of human perception and cognition. He received a Distinguished Scientific Award of the American Psychological Association for early career research into visual perception, the Rustum Roy Award of the Chopra Foundation and the Troland Research Award of the US National Academy of Sciences.’

 

All of the above I’ve lifted verbatim from the About The Author section to his book, The Case Against Reality (2019). The copy I have is Penguin paperback (2020). The subtitle is How evolution hid the truth from our eyes. I first came across Hoffman 10 years ago (2016), when someone sent me a link to an academic paper he cowrote with Chetan Prakash called Objects of Consciousness, which I reviewed back then.

 

All of this gives Hoffman enormous credibility, without even mentioning that he had direct communication with Francis Crick before the latter died. His book is obviously aimed at people like myself, who have an interest in science but are not academic, with the intention of convincing us that his ideas are unassailable. But the truth is that by the time I reached the end of his book, I was more convinced that he was wrong than when I started. Now that’s a huge admission given the extraordinary gap in our credentials not to mention the limitations of my knowledge in neuroscience.

 

I wrote a post some time ago, where I talked about how important beliefs are in the development of science. What I’ve learned from watching various science experts on YouTube, who have, what one might call, ‘fringe ideas’, is that they form a very strong belief and then look for the evidence to support it. I include myself in this, even though I’m not a scientist. My fringe idea is that there is a universal now, and I think this is consistent with relativity theory, even though everyone will tell you that I’m wrong. The one thing going in my favour is that the Universe appears to have an edge in time and a finite age, which runs contrary to the orthodox view that there is no objective now. From what I’ve seen and read, physicists gloss over this conundrum, including Brian Greene in his excellent book, The Fabric of the Cosmos.

 

A better example is cosmologist Claudia de Rahm, who is one of the very few scientists (perhaps the only one with the necessary expertise) who thinks that gravitons could have mass. The point is that we don’t even know if gravitons exist, and she readily acknowledges, that if they do exist, they might be impossible to detect.

 

So I can’t criticise Hoffman simply because his ideas are ‘out there’; it’s not uncommon among scientists, including famous ones like Sir Roger Penrose.

 

This is a lengthy preamble, but I want to make one other point, before I get into the nitty gritty of his arguments. I wrote a post once on how I believe science works, which, in a nutshell, builds on what we already know, even when we have so-called revolutions in science. Ever since the scientific revolutions of Copernicus, Galileo, Kepler, and of course, Newton and Leibniz, our theories have extended science rather than outright replaced what went before. Claudia de Rahm (cited above) in answer to an audience question I watched online, made the explicit point that whatever new discoveries we make, they have to explain what we already know, so we don’t just throw everything in the rubbish bin (to use her turn-of-phrase).

 

Many people don’t know that one of Einstein’s self-imposed constraints on his General Theory of Relativity (GR) was that it had to agree mathematically with Newton’s theory of gravity when relativistic effects were negligible. Likewise, quantum mechanics (QM) hasn’t so much replaced classical physics, as added to it and possibly underpins it. UK based Aussie physicist, Mithuna Yoganathan (from the Looking Glass Universe YouTube channel) has made the point that she’s attracted to the many worlds interpretation (MWI) of QM because she can’t accept that the Universe obeys 2 sets of rules: for quantum mechanics and classical physics. The fact that she even mentions it suggests to me that it’s quite plausible, in which case, QM adds new physics without completely overturning the old.

 

The reason I’ve spent so much time on this detour is that, according to Hoffman, we need to reinvent virtually all the physics of the past 4-500 years, as well as evolutionary theory.

 

In fact, Hoffman states that “ITP asserts that one theory of objective reality – that it consists of physical objects in spacetime – is false.” (p.82) Einstein’s GR, mentioned earlier, is one such theory and currently underpins the latest cosmological model, specifically ΛCDM. ITP is Hoffman’s ‘Interface Theory of Perception’ which he analogises with a desktop interface on a computer, and to extend the analogy, the ‘objects’ we perceive are like ‘icons on the desktop’, so not ‘real’. I’ll return to this point later, given its significance to his argument.

 

After reading his book, I have many philosophical differences with Hoffman, but there is one point in particular, which is central to his entire thesis, where I’d argue the evidence contradicts him. I’m calling it the ‘principle of object permanence’. I admit I made that up, but it’s something that I argue evolution by natural selection selected for, because it’s a principle we not only take for granted but is cognitively found in babies and other animals. In other words, it’s the fundamental belief that an object still exists when we can’t see it. I will give an example of its ‘evolutionary value’ shortly, but it’s the direct opposite of what Hoffman believes. And I mention its evolutionary value because key to Hoffman’s theory is that evolution by natural selection supports his position and not mine.

 

He calls his theorem FBT, ‘Fitness-Beats-Truth’, which effectively means that evolution selects for fitness, not truth, while being somewhat hand-wavy about what those terms mean and how they can be quantified. The one example he provides in his book is a graphic representation. In fact, all his ‘evidence’ is based on computer modelling according to the examples he gives. He combines FBT with ITP (already mentioned), asserting they prove that he’s right: object permanence does not exist (as I defined it above).

 

I’m not going to try and prove his FBT or ITP wrong; I’m going to show why I believe the principle of object permanence is a necessary belief for evolutionary fitness. Now Hoffman would agree that the perception of object permanence affects evolutionary fitness but that doesn’t mean it’s real. However, I contend that it can make the difference between life and death, which does make it real.

 

I will give an example I read about once, involving crows not humans, which I assume really happened. Actually, it involved crows and humans, but it’s the cognitive ability of the crow that’s tested. A human with a gun set a trap for a crow using bait, then went into hiding until the crow took the bait. The crow, however saw the man go into hiding, and believing in object permanence waited patiently till the man left. Then the man got a companion, and this time the crow waited until both of them left. So they repeated the exercise using 3 gunmen and this time after 2 left, the crow thought it was safe, only it wasn’t. The exercise proved that the crow couldn’t count past 2. But you can see how a belief in object permanence can be critical to survival.

 

Now Hoffman has an answer to this, because it’s comparable to being hit by a car or being killed by any so-called object in his ‘interface’ (hence the name, ITP). He would say you need to take the car ‘seriously but not literally’. I admit I have a problem with that statement: I take the car ‘seriously’ because it can kill me but I don’t take it ‘literally’ because it’s not ‘real’. Hoffman keeps comparing this to someone playing Grand Theft Auto on a computer, because we live in an ‘interface’ not spacetime and there are no objects, only ‘icons’, including your own body. He later argues we don’t live in a computer simulation, which I’ll return to.

 

For examples of truth that evolution didn’t select for, he mentions oxygen and ultraviolet light causing sunburn. His point is that in both cases we don’t need to know about oxygen in order to know that the ability to breathe air confers fitness or know about ultraviolet light to know that keeping our skin covered against prolonged exposure to sunlight also confers fitness. By these examples, truth means explanations, to which I’d agree: evolution doesn’t select for explanations and I wrote about that elsewhere, while also discussing Hoffman. Note how sunlight and air exist externally to us.

 

Returning to my principle of object permanence, Hoffman cites Einstein’s famous retort to Bohr, ‘Do you think the moon ceases to exist when you’re not watching?’ It turns out that Hoffman does: “There is no objective moon or spacetime that exists even when unperceived…” (p.198)

 

I would like to know how that affects the tides occurring all around the world, although, according to Hoffman, there is no ‘around the world’, because there is no 3-dimensional space, and there is no cause and effect. He also claims that DNA and chromosomes don’t exist unperceived which turns evolutionary theory on its head. I discussed that in my original post on Hoffman. It reinforces my earlier point that Hoffman’s theory requires all of science to be replaced, including evolutionary theory as well as cosmology. He doesn’t explain how DNA and chromosomes can only exist when observed, yet underpin evolutionary theory as we currently know and understand it. He also claims the same for neurons in the brain, meaning consciousness creates them rather than the converse, which is the consensus of virtually all neuroscientists. Hoffman acknowledges this fundamental disagreement.

 

He spends a lot of time discussing optical illusions in considerable detail as supporting evidence that what we perceive is not real. I agree with him that our sensory experiences, like colour, sound and smell are all totally subjective and that other animals’ sensory experiences can be completely different to ours. We know that some animals can see colours we can’t and vice versa, and some can hear sounds that we can’t. But here’s the thing: colours are created by reflected light from an external source, and sounds are caused by vibrations transmitted through a medium, like air, and we’re evolutionarily adapted to pick them up and transform them into sensory experiences. To use his terms, the ‘fitness’ is our sensory experience and the ‘truth’ is our explanation of their external origins. So, yes, we evolved for fitness, not a scientific understanding called truth, but that doesn’t rule out object permanence (as described above) nor their location in space and time.

 

For the sake of brevity, I can’t address all his points but there is one other I find particularly contentious, and that is the idea that 3 dimensions of space are redundant, and we only need 2. Hoffman cites the cosmological holographic principle, which is basically the idea that all the (quantum) information inside a black hole is available holographically on the surface of its event horizon, which, it needs to be pointed out, is a sphere. Some argue that our entire universe could be modelled on the same principle, that everything in it could be a hologram projected from a 2-dimensional horizon. Hoffman argues that since all the information can be contained in 2 dimensions the third dimension of space that we ‘perceive’ is redundant and is used for ‘error-correction’. Aside from this being highly speculative physics, Hoffman overlooks the fact that the 2-dimensional surface of an event horizon on a sphere can only exist in 3-dimensional space; a hollow sphere in 2 dimensions becomes a circle.

 

But there is more: the inverse square law for gravity, which is in both Newton’s and Einstein’s theories, is a direct consequence of space being 3-dimensional. John Barrow gives the best account I’ve come across in his excellent book, The Constants of Nature. Given Hoffman’s access to academia, I’d recommend he talk to Barrow, or at least, read his book. Hoffman quotes Arkani-Hamed in a 2014 lecture at the Perimeter Institute: “Almost all of us believe that spacetime doesn’t exist; that spacetime is doomed, and has to be replaced by some more primitive building blocks.” (p.114) Now, I’m obviously not familiar with Arkani-Hamed’s work, but Graham Farmelo (The Universe Speaks in Numbers) also quotes Arkani-Hamed in a different context, which is the success of mathematical objects called amplituhedrons in predicting the amplitude of gluons in particle physics. Note this has an experimental physics basis, and is not just theoretical.

 

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. (my emphasis)

 

Now, I know that some physicists are speculating that spacetime might be an emergent property from something deeper (as inferred in the above quote from Arkani-Hamed), but that’s not the same as saying it doesn’t exist. If, on the other hand, Arkani-Hamed really believes that ‘spacetime doesn’t exist’, then he needs to replace the highly successful GR with something else. He also needs to explain the cosmological history based on the observable CMBR (cosmic microwave background radiation) that is the remnant of the Big Bang (13.8 billion years ago). I don’t know how you can have a cosmological history without spacetime. Hoffman challenges this by arguing for a ‘top-down cosmology’, that starts with an observer, but that’s another topic for another time.

 

In fact, Hoffman argues that conscious agents generate spacetime and all the physics we currently know, including quantum mechanics.

 

Conscious realism must ground a theory of quantum gravity, explain the emergence of our spacetime interface, and its objects, explain the appearance of Darwinian evolution within that interface, and explain the evolutionary emergence of human psychology. (pp.198-9)

 

We must show how conscious agents generate spacetime, objects, physical dynamics and evolutionary dynamics. We must get back quantum theory and general relativity, and generalisations of these theories that are mathematically precise. (p.184-5)

 

Hoffman does this by creating a mathematical model of consciousness that apparently generates all of what we call objective reality. He reveals this in an appendix, titled, Precisely; The Right to Be Wrong. He doesn’t make it clear who has ‘the right to be wrong’: himself or the rest of us. It’s very obtuse mathematics, in the form of logic rather than equations, but basically, he creates a mathematical formula for ‘conscious agents’, and then, using ‘Markovian dynamics’, effectively derives spacetime. I don’t pretend I can follow it. He concludes by saying: “…perhaps a dynamic evolution of conscious agents toward small-world networks may appear in spacetime as the dynamics of gravity.” (p.205) I think the words, ‘perhaps’ and ‘may’, do a lot of heavy-lifting. To provide context, Hoffman argues that it’s networks of ‘conscious agents’, not individuals, that generate the world we call reality.

 

Earlier this year, I attended a 2hr stage presentation by Prof Brian Cox, which was very esoteric, discussing wormholes, black holes and other cosmological exotica, but he never mentioned that ‘spacetime is doomed’; so that’s the orthodox view.

 

In summary, I have 2 fundamental contentions with Hoffman, without even considering his ideas on evolution. Anyone who has lost an object (like car keys) knows they still exist unobserved, including Hoffman, I suspect. He will rationalise that he takes them ’seriously but not literally’. However, that explains nothing, unless you’re in a video game (refer below). My argument is that evolution confers fitness on perceiving ‘object permanence’ because it’s a matter of life-and-death, as per my crow story.

 

My second contention is that we live in 3D not 2D. To demonstrate, draw an animal, any animal, on paper, so it’s flat and you can cut it out. Then draw an alimentary canal from its mouth to its anus. If you then cut it out, it falls apart into 2 pieces. This is as good a reason as any why we don’t live in a 2D universe. Hoffman mentions, in passing, while discussing something else, that he can’t visualise 4D, and there’s a good reason for that: we don’t need to; even though we can represent any finite dimensional world mathematically. The reason we can only visualise 3D and less, is because we live in a 3D world.

 

Hoffman finishes his main text (before the Appendix) with this:

 

Spacetime is your virtual reality, a headset of your own making. The objects you see are your inventions. You create them with a glance and destroy them with a blink. You have worn this headset all your life. What happens when you take it off? (p.202)

 

Despite claiming that he doesn’t believe we live in a computer simulation, his description of ‘reality’ is indistinguishable from one. This is demonstrated by calling objects and even his own body, ‘icons’, and that he believes the world is 2D like a screen, which we erroneously perceive as 3D (according to him), because it increases our evolutionary fitness.

 

He reinforces that view here: “The interface theory of perception contends that there is a screen – an interface – between us and objective reality.” (p.191, my emphasis)

 

Later he talks about spirituality, which I won’t elaborate on, except to say that the idea that consciousness can escape its physical constraints, as opposed to creating them, is not ruled out or ruled in.

Addendum: I admit to indulging in a fantasy of ‘talking’ to Donald Hoffman, so we could have a Socratic conversation.