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.

Can one overcome adversity without free will?

I recently read a book titled being (no capital) written by a father and daughter (Ross G. Menzies and Rachel E. Menzies), both academics in psychology, albeit at different institutions in Sydney. The subtitle is Why It’s Harder To Be A Human Than A Hamster Or A Herring, which I think is a little misleading, and probably unnecessary.

For me, the title, being, says it all, because it’s a category on my blog. ‘Being’ is literally about being human, with all that entails, including the fact that we are a complex social species who thinks in a complex language, which is akin to software in that it’s hard to imagine thinking without it. That alone differentiates us from all other species, but, having read their book, I really don’t think that’s what it's about.

 

The book has a strong existential flavour, because it’s really about how to take control of your inner self and therefore your life. And perhaps that would have been a better subtitle, and even shifted more books. But perhaps the authors wanted to differentiate themselves from the plethora of self-help books on the market, and I can understand that, because I don’t think this book fits that genre either. It’s more Oliver Sacks than Oprah Winfrey. In particular, they provide examples of case studies (like Sacks did in his seminal tome, The Man Who Mistook His Wife for a Hat), which are all extreme cases, yet illustrate their points.

 

I found myself identifying with a lot of what they described, and perhaps others will too. In particular, they explain how we all have an inner voice that can be our biggest critic and can inhibit us. I’m really not sure how widespread this is: I can’t imagine narcissists having a critical inner voice; I imagine their inner voice never stops telling them how exceptional and brilliant they are. Just listen to Donald Trump’s public exhortations of his own genius.

 

Basically, the authors are saying this inner voice can have pathological consequences, and I know mine never shuts up. They make the point that it was probably fostered in childhood, and I can certainly testify to that. But here’s the thing: I’ve come to see it as a positive, because it helps to keep my ego in check, and I agree with Socrates’ maxim about the unexamined life. It was also a feature of Confucius’ philosophy: that self-examination is a bulwark against our propensity to blame others for our shortcomings. Note that they both lived around 4-500 years before Christ.

 

The book includes a couple of questionnaires, which the reader is invited to try, and I complied.

 

One was about one’s search for purpose or meaning. It was only 10 questions but it was cleverly designed to ascertain 2 parameters: how strong is one’s search for meaning; and how strong is one’s sense of having acquired meaning or purpose. They are meant to be complementary in that a high score on one should be reflected by a low score on the other. I scored high on both: 29 out of 35.

 

They don’t address that anomaly, but my takeaway is that my sense of purpose is probably a lot higher than it was when I was younger; yet I’m still searching, in the belief that there is no final destination. I think this blog encapsulates both of those.

 

The other one was a measure of regret with only 5 questions, and I scored 9 out of 35, which is roughly what I expected. The questions were about reflecting on outcomes and considering what-ifs.

 

They reference Carl Rogers and, in particular, his mostly unacknowledged influence on the relationship between psychologists and their clients. In particular, in creating a non-judgemental environment. I remember that Carl Rogers was barely mentioned when I studied psychology, yet I’d read about his ‘client-centred therapy’ external to my studies.

 

Given their book has an unapologetic existential influence, I was surprised by their views on free will. Basically, they take the very strong scientific position that it’s a fallacy.

 

Following a chapter titled The Forks in the Road, which is about decision-making as the title suggests, there is a chapter titled The Illusion of Freedom, headlined by a quote from Sam Harris: You can do what you decide to do – but you cannot decide what you will decide to do. And that sums up what they talk about for the next 28 pages.

 

But let me backtrack momentarily to The Forks in the Road where they discuss something called the ‘Indecisiveness Scale’ devised by Robert Frost and Deanna Shows at Smith College, Northampton, Massachusetts, in the 1990s. To quote the authors:

 

This simple, fifteen-item scale has been used by researchers around the globe for decades and has revealed just how destructive to wellbeing indecisiveness really is. (My emphasis)

 

Across investigations, high scores on the Indecisiveness Scale have been linked to high levels of negative emotion, worry, depression and rumination.

 

One section of this chapter was subtitled, Maximising versus satisficing, and basically, giving examples, the authors explain how satisficing is better than maximising as a life enhancing strategy. Basically, maximising means always seeking and demanding the optimum outcome, and satisficing means making compromises and accepting the best outcome in a given situation.

 

Possibly, you can see a connection to the notion of free will, given we associate decision-making to the attribute of personal agency. Therefore, the Illusion of Freedom was like a bucket of cold water, in the face of what went before.

 

Essentially, they argue we are nothing more than ‘biological machines’. They quote from a previous book of theirs (which I haven’t read):

 

The decisions we believe we’re making ‘freely’ are all in fact determined by a dense thicket of crisscrossing cogs and causes – biographical, physiological, cultural, psychological, neurological and environmental… We are incredibly complex creatures, entwined in incredibly complex situations, which makes our choices often seen baffling and unpredictable, but we are nonetheless, ultimately, biological machines that obey the laws of physics just like everything else. (my emphasis)

 

That last sentence reminds me of Sabine Hossenfelder, and in fact, they reference her book at one point, Existential Physics (which I have read). But the main problem I have with their thesis is how they reverse the norm when it comes to dealing with failures. They give the example of Italian soccer player, Roberto Baggio, who famously (or infamously) missed a penalty goal in the 1994 FIFA World Cup final against Brazil, held in Pasadena, California. Other than the personal shame and humiliation, it effectively curtailed a brilliant career. The authors argue that the way he should have dealt with it, was to acknowledge that he had no free will.

 

I find this such a self-defeating attitude. Does that mean that all the brilliant successes he’d had up to that point in his star-studded career were also just a product of being a robotic ‘biological machine’? My point is that if you’re going to take responsibility for your triumphs you also need to take responsibility for your failures. Anything else is a cop-out. It’s why Socrates’ famous aphorism: The unexamined life is not worth living; is so resonant throughout the ages. We only examine our lives when we fail, and Socrates had failed to prevail against the Senate and paid for it with his life.

 

To provide a counter perspective, I watched a 97m YouTube video provided by Robert Lawrence Kuhn’s Closer to Truth channel, titled, Big Questions in Free Will. It covered a four-year project (so not a one-week seminar as you might expect), with experts in psychology, neuroscience, philosophy and theology. The theology component was separate and is covered at the end, and assumes free will, but discusses the apparent contradiction with having an omnipotent and omniscient God with human free will, which I won’t discuss here. I read a book on that topic by Clifford A Pickover (The Paradox of God And the Science of Omniscience), which I discussed in another post.

 

Overall, Kuhn’s video is an excellent exposition on the topic, based on interviews with various experts, and it revealed that free will is more nuanced than what many people claim, including myself. Basically, there are a lot of thoughts, impulses and ideas that come into your mind that you don’t have conscious control over. I think the most obvious example is when one dreams. In a dream, there is a sense that we don’t have control over events, even though I believe there is a conscious interaction. But anyone who has done something creative is aware that there is a strong subconscious component – we literally don’t know where it comes from.

 

Of all the participants (over 20), there were 2 in particular, who came closest to expressing my beliefs: Eddy Nahmias, Professor of Philosophy at Georgia State University, and Peter Tse, Professor of Psychology at Dartmouth College. Both expressed the view that decisions requiring detailed cognitive analysis with potentially life-changing consequences, like getting married or changing careers, were not solely the result of subconscious impulses. My own view, not expressed by any of the participants, is that consciousness can act as a feedback loop and modify a subconscious decision. Peter Tse alluded to this without calling it a loop. Douglas Hofstadter coined the term, ‘strange loop’ to describe this experiential phenomenon.

 

Peter Tse’s interaction with his colleague, Thalia Wheatley (Associate Professor of Psychology at Dartmouth College) was most interesting and informative, because Thalia held the view that free will is a chimera (my term, not hers), the same as Rachel and Ross Menzies. At one point, Tse mentions the role of imagination, which I’ve argued before is the key to free will – an idea I’ve borrowed from Raymond Tallis (neuroscientist turned philosopher).

 

I’ve long argued that consciousness without free will makes no evolutionary sense. If consciousness simply makes us aware of decisions already made, then what’s the point? On the other hand, consciousness can access memory and mentally time travel – hence the role of imagination – because that’s what imagination does. The ability to mentally time travel, especially into the future, allows us to consider the far-reaching consequences of events like getting married or changing careers or any other life-changing decision.

 

Getting back to the Menzies’ position and the subtext of their book, which is really about trying to live a more fulfilling life. I’ve spoken about this before, but I went through a phase in my life where I felt I had no control and I became a fatalist – believing that everything was caused by fate. Not surprisingly, I became very depressed. The fact that I overcame this, I put solely down to free will – the belief that one can change one’s circumstances, by taking control and responsibility for one’s decisions.

 

The authors don’t mention impostor syndrome, but I suspect I’ve suffered from a version of that my whole life, although I don’t necessarily think that’s a bad thing. I think it gives one perspective and stops one from being full of themselves. Ex New Zealand Prime Minister, Jacinda Ardern, said she suffered from imposter syndrome, but gave the impression that it helped her because it imbues humility in the face of dealing with significant events. It’s not lack of confidence, as she was quick to point out, but it requires self-examination, which requires a feedback loop.