Tag: quantum superposition

A ‘quantum consciousness’ absurdity at IIT Mandi

As you go downward, inward, smaller and smaller, you get more vast conscious experience. This is the idea in Indian knowledge systems. At the bottom of it, or the very base of it, at the source, is Brahman. My point is that this is actually very consistent with what we’re learning about how consciousness may be produced in our brain due to quantum effects.

The person who made this statement is Stuart Hameroff, at the 10th convocation at IIT Mandi on December 5. Hameroff is a neuroscientist and anaesthesiologist. Since 1975, he has been at the University of Arizona, where, in 1999, he became professor in the department of anaesthesiology and psychology and the director for the Center for Consciousness Studies. He became an emeritus professor in 2003. He is famous for his part in the Orch-OR hypothesis of how consciousness originates in the brain. Hameroff and Roger Penrose (who won the Nobel Prize for physics in 2020 for unrelated work) collaborated on the idea and published a few papers detailing their assumptions and conclusions.

‘Orch-OR’ stands for ‘orchestrated objective reduction’. Broadly speaking, the hypothesis is that the states of microtubules, which are cellular structures inside neurons, enter into a quantum superposition – becoming like the cat inside the unopened box in the Schrödinger’s cat thought-experiment. The superposition is then forced to collapse (‘the box is opened’) in favour of one state by gravity. This is taken to be the moment when consciousness comes ‘on’. One scheme of the hypothesis says that when the superposition collapses, the process should release some electromagnetic radiation – a testable prediction.

Experiments looking for this radiation have come up empty. One experiment whose results were published in May 2022 found that the brain would have to have 1,000-times more of the cells that make up microtubules than it actually does, disfavouring the hypothesis in a range of space- and time-scales, albeit not entirely. The hypothesis is also largely controversial and doesn’t find favour among most physicists, who have been critical of Penrose’s calculations of how the gravity-mediated superposition collapse happens.

To be sure, there has been some evidence that quantum phenomena might be going on in the human brain; what we don’t have evidence for is sophisticated hypotheses like Orch-OR that claim a precise origin of consciousness.

So Hameroff’s statement at IIT Mandi that the concept of the ‘Brahman’ “is actually very consistent with what we’re learning about how consciousness may be produced in our brain due to quantum effects” is at best disingenuous. What we are learning is that Orch-OR is quite unlikely to be a valid explanation of the emergence of consciousness in the brain; and we are certainly not finding support for Orch-OR by shoehorning the concept of the ‘Brahman’ and spiritual ideas of consciousness into gravity’s effects on hypothetical forms of spacetime.

But his talk gets worse. A few minutes later, Hameroff says that consciousness appears to straddle the shared border between the quantum and the classical worlds, that the phenomenon of quantum state reduction (a.k.a. superposition collapse) is akin to the emergence of the “Atman from the Brahman”, and that he wondered “whether the many faces of Krishna were a quantum superposition”. He continues:

Under normal circumstances, the people back then didn’t see Krishna in superposition but as one, but knew in different ways that there could be this apparent superposition of many possible faces of Krishna.

So here we have a scientist who once helped develop and support a difficult hypothesis to explain a famously intractable problem using the methods of science, but who has now gone so far as to claim that a) a Hindu deity was a real person, b) he had many heads, and c) people didn’t see these heads but d) knew that he could have many faces, and e) understood them to be in an “apparent superposition”. What are we to make of this waterfall of nonsense?

His claims aren’t false because they’re unfalsifiable. Consider just one: Hameroff is postulating that macroscopic superposition could have been real (regarding the face of a human being, but let’s set that aside).

Quantum computers work by manipulating qubits, the smallest units of information in these machines, using quantum phenomena like superposition and entanglement. The computer’s result is the state to which the qubits’ superposition collapses. But unlike classical bits, which are made of semiconductors, qubits are very fragile systems and must be protected against external disturbances, even small amounts of electromagnetic radiation. If a qubit is disturbed, it will lose the ability to participate in the quantum computer in a process called decoherence.

To date, despite researchers’ best efforts, they haven’t built a quantum computer that completely eliminates errors arising out of decoherence. They also haven’t built quantum computers that can solve practical problems, like modelling stresses on a bridge or synthesising a drug with certain components either, meaning more complex machines will present more significant decoherence barriers. And quantum computers use subatomic (microscopic) particles as qubits.

There is no evidence to date of macroscopic objects being in perfect superposition, forget an entity as complicated and ‘noisy’ as a human face or body. Hameroff’s other claims require less explanation as to their absurdity.

There is a good chance he was invited to IIT Mandi with full knowledge of his views. Since 1994, Hameroff has been conducting a conference every year called ‘Science of Consciousness’, where some consciousness researchers present some notable ideas and results while others… Let me quote Tom Bartlett writing for The Guardian in 2018:

While the Science of Consciousness event has, technically, three programme chairs and an advisory committee, it is more or less The Stuart Show. He decides who will and who will not present. And, to put it nicely, not everyone is in love with the choices he makes. To put it less nicely: some consciousness researchers believe that the whole shindig has gone off the rails, that it is seriously damaging the field of consciousness studies, and that it should be shut down.

In 2012, Hameroff said,

“Let’s say the heart stops beating, the blood stops flowing, the microtubules lose their quantum state. The quantum information within the microtubules is not destroyed, it can’t be destroyed, it just distributes and dissipates to the universe at large. … If the patient is resuscitated, revived, this quantum information can go back into the microtubules and the patient says ‘I had a near death experience’. If they’re not revived, and the patient dies, it’s possible that this quantum information can exist outside the body, perhaps indefinitely, as a soul.”

In the Copenhagen interpretation of quantum mechanics, a superposition of states collapses into a single state when an observation is made on the system. What counts as an act of observation has been refined over the years: today, physicists understand that the collapse happens when the information required to describe the superposition is no longer locally available. In this sense, Hameroff’s delineation above seems to hew close to reality – but we have absolutely no way of saying that quantum information is the same as a soul!

As Jim Al-Khalili, an expert in quantum biology, said in 2020 about Orch-OR:

“There was some brief excitement about this idea initially, but I think very quickly most scientists said: ‘No, hang on a minute, just because quantum mechanics is mysterious and we don’t understand it and consciousness is mysterious and we don’t understand it, it doesn’t mean that the two have to be connected’.”

So Hameroff has been making dubious claims for a long time, including claims for at least a decade that overlook the differences between a knowledge system concerned with verifiable truths and the elimination of bias and one that is concerned with harmonising reality and perception regardless of tests – and the pitfalls of claiming that a ‘fact’ in one system could be wholly equivalent to a ‘fact’ in the other. To quote philosophy scholar S.K. Arun Murthi:

While [ancient Indian] systems of thought are called philosophical systems, they are unified in their aim: salvation and liberation of the soul. One question that has frequently been the topic of discussion in scholarly circles is whether Indian culture and civilisation really recognised an independent discipline called ‘philosophy’ as a discursive analytic tradition. The question arises because all its schools have been restricted to theological and soteriological concerns.

Surendranath Dasgupta even begins his aforementioned book with a note of caution, that Indian thought always manifested itself “in an yearning after the Infinite” and that “Hindus never busied themselves about the investigation of the laws of nature except in so far as it was connected with the general philosophical speculations”.

The other knowledge system, science, requires evidence, but Hameroff has none. Yet in May 2022 Hameroff again wrote:

“Light is the part of the electromagnetic spectrum that can be seen by the eyes of humans and animals – visible light. … Ancient traditions characterized consciousness as light. Religious figures were often depicted with luminous ‘halos’, and/or auras. Hindu deities are portrayed with luminous blue skin. And people who have ‘near death’ and ‘out of body’ experiences described being attracted toward a ‘white light’. In many cultures, those who have ‘awakened to the truth about reality’ are ‘enlightened’.”

(A few months earlier, Laxmidhar Behera, the director of IIT Mandi, had expressed belief and experience in exorcisms and that students should rid their friends’ parents of evil spirits using chants.)

Armchair logicians and social-media loudmouths will now interpret Hameroff’s talk as ‘evidence’ of ancient India’s intellectual supremacy and as his tacit endorsement of the physical reality of Hindu deities and the sophisticated ideas that sages and scholars of the time contemplated. Hameroff also says that “therapies aimed at microtubule resonance e.g. with painless, safe and pleasant brain ultrasound can treat mental and cognitive disorders”, extending a handle to many quacks already using quantum-physics gobbledygook to con unsuspecting care-seekers.

There may be some who truly believe such statements while others will wield it to further an agenda while knowing well that the claims are less than flimsy. Either way, the task in front of the debunker is much more devious: to set out not just the laws of nature and the methods of science but also the work of Hameroff and Penrose, the criticism against it, why expertise is not a carte blanche, the incommensurability of the knowledge systems involved, and the fine line between ‘absence of evidence’ and ‘evidence of absence’.

A quantum theory of consciousness

We seldom have occasion to think about science and religion at the same time, but the most interesting experience I have had doing that came in October 2018, when I attended a conference called ‘Science for Monks’* in Gangtok, Sikkim. More precisely, it was one edition of a series of conferences by that name, organised every year between scientists and science communicators from around the world and Tibetan Buddhist monks in the Indian subcontinent. Let me quote from the article I wrote after the conference to illustrate why such engagement could be useful:

“When most people think about the meditative element of the practice of Buddhism, … they think only about single-point meditation, which is when a practitioner closes their eyes and focuses their mind’s eye on a single object. The less well known second kind is analytical meditation: when two monks engage in debate and question each other about their ideas, confronting them with impossibilities and contradictions in an effort to challenge their beliefs. This is also a louder form of meditation. [One monk] said that sometimes, people walk into his monastery expecting it to be a quiet environment and are surprised when they chance upon an argument. Analytical meditation is considered to be a form of evidence-sharpening and a part of proof-building.”

As interesting as the concept of the conference is, the 2018 edition was particularly so because the field of science on the table that year was quantum physics. That quantum physics is counter-intuitive is a banal statement; it is chock-full of twists in the tale, interpretations, uncertainties and open questions. Even a conference among scientists was bound to be confusing – imagine the scope of opportunities for confusion in one between scientists and monks. As if in response to this risk, the views of the scientists and the monks were very cleanly divided throughout the event, with neither side wanting to tread on the toes of the other, and this in turn dulled the proceedings. And while this was a sensible thing to do, I was disappointed.

This said, there were some interesting conversations outside the event halls, in the corridors, over lunch and dinner, and at the hotel where we were put up (where speakers in the common areas played ‘Om Mani Padme Hum’ 24/7). One of them centered on the rare (possibly) legitimate idea in quantum physics in which Buddhist monks, and monks of every denomination for that matter, have considerable interest: the origin of consciousness. While any sort of exposition or conversation involving the science of consciousness has more often than not been replete with bad science, this idea may be an honourable exception.

Four years later, I only remember that there was a vigorous back-and-forth between two monks and a physicist, not the precise contents of the dialogue or who participated. The subject was the Orch OR hypothesis advanced by the physicist Roger Penrose and quantum-consciousness theorist Stuart Hameroff. According to a 2014 paper authored by the pair, “Orch OR links consciousness to processes in fundamental space-time geometry.” It traces the origin of consciousness to cellular structures inside neurons called microtubules being in a superposition of states, and which then collapse into a single state in a process induced by gravity.

In the famous Schrödinger’s cat thought-experiment, the cat exists in a superposition of ‘alive’ and ‘dead’ states while the box is closed. When an observer opens the box and observes the cat, its state collapses into either a ‘dead’ or an ‘alive’ state. Few scientists subscribe to the Orch OR view of self-awareness; the vast majority believe that consciousness originates not within neurons but in the interactions between neurons, happening at a large scale.

‘Orch OR’ stands for ‘orchestrated objective reduction’, with Penrose being credited with the ‘OR’ part. That is also the part at which mathematicians and physicists have directed much of their criticism.

It begins with Penrose’s idea of spacetime blisters. According to him, at the Planck scale (around 10-35 m), the spacetime continuum is discrete, not continuous, and that each quantum superposition occupies a distinct piece of the spacetime fabric. These pieces are called blisters. Pernose postulated that gravity acts on each of these blisters and destabilises them, causing the superposed states to collapse into a single state.

A quantum computer performs calculations using qubits as the fundamental units of information. The qubits interact with each other in quantum-mechanical processes like superposition and entanglement. At some point, the superposition of these qubits is forced to collapse by making an observation, and the state to which it collapses is recorded as the computer’s result. In 1989, Penrose proposed that there could be a quantum-computer-like mechanism operating in the human brain and that the OR mechanism could be the act of observation that forces it to terminate.

One refinement of the OR hypothesis is the Diósi-Penrose scheme, with contributions from Hungarian physicist Lajos Diósi. In this scheme, spacetime blisters are unstable and the superposition collapses when the mass of the superposed states exceeds a fixed value. In the course of his calculations, Diósi found that at the moment of collapse, the system must emit some electromagnetic radiation (due to the motion of electrons).

Hameroff made his contribution by introducing microtubules as a candidate for the location of qubit-like objects and which could collectively set up a quantum-computer-like system within the brain.

There have been some experiments in the last two decades that have tested whether Orch OR could manifest in the brain, based on studies of electron activity. But a more recent study suggests that Orch OR may just be infeasible as an explanation for the origin of consciousness.

Here, a team of researchers – including Lajos Diósi – first looked for the electromagnetic radiation at the instant the superposition collapsed. The researchers didn’t find any, but the parameters of their experiment (including the masses involved) allowed them to set lower limits on the scale at which Orch OR might work. That is, they had a way to figure out a way in which the distance, time and mass might be related in an Orch OR event.

They set these calculations out in a new paper, published in the journal Physics of Life Reviews on May 17. According to their paper, they fixed the time-scale of the collapse to 0.025 to 0.5 seconds, which is comparable to the amount of time in which our brain recognises conscious experience. They found that at a spatial scale of 10-15 m – which Penrose has expressed a preference for – a superposition that collapses in 0.025 seconds would require 1,000-times more tubulins as there are in the brain (1020), an impossibility. (Tubulins polymerise to form microtubules.) But at a scale of around 1 nm, the researchers worked out that the brain would need only 1012 tubulins for their superposition to collapse in around 0.025 seconds. This is still a very large number of tubulins and a daunting task even for the human brain. But it isn’t impossible as with the collapse over 10-15 m. According to the team’s paper,

The Orch OR based on the DP [Diósi-Penrose] theory is definitively ruled out for the case of [10-15 m] separation, without needing to consider the impact of environmental decoherence; we also showed that the case of partial separation requires the brain to maintain coherent superpositions of tubulin of such mass, duration, and size that vastly exceed any of the coherent superposition states that have been achieved with state-of-the-art optomechanics and macromolecular interference experiments. We conclude that none of the scenarios we discuss … are plausible.

However, the team hasn’t nearly eliminated Orch OR; instead, they wrote that they intend to refine the Diósi-Penrose scheme to a more “sophisticated” version that, for example, may not entail the release of electromagnetic radiation or provide a more feasible pathway for superposition collapse. So far, in their telling, they have used experimental results to learn where their theory should improve if it is to remain a plausible description of reality.

If and when the ‘Science for Monks’ conferences, or those like it, resume after the pandemic, it seems we may still be able to put Orch OR on the discussion table.

* I remember it was called ‘Science for Monks’ in 2018. Its name appears to have been changed since to ‘Science for Monks and Nuns’.

The problem with rooting for science

The idea that trusting in science involves a lot of faith, instead of reason, is lost on most people. More often than not, as a science journalist, I encounter faith through extreme examples – such as the Bloch sphere (used to represent the state of a qubit) or wave functions (‘mathematical objects’ used to understand the evolution of certain simple quantum systems). These and other similar concepts require years of training in physics and mathematics to understand. At the same time, science writers are often confronted with the challenge of making these concepts sensible to an audience that seldom has this training.

More importantly, how are science writers to understand them? They don’t. Instead, they implicitly trust scientists they’re talking to to make sense. If I know that a black hole curves spacetime to such an extent that pairs of virtual particles created near its surface are torn apart – one particle entering the black hole never to exit and the other sent off into space – it’s not because I’m familiar with the work of Stephen Hawking. It’s because I read his books, read some blogs and scientific papers, spoke to physicists, and decided to trust them all. Every science journalist, in fact, has a set of sources they’re likely to trust over others. I even place my faith in some people over others, based on factors like personal character, past record, transparency, reflexivity, etc., so that what they produce I take only with the smallest pinch of salt, and build on their findings to develop my own. And this way, I’m already creating an interface between science and society – by matching scientific knowledge with the socially developed markers of reliability.

I choose to trust those people, processes and institutions that display these markers. I call this an act of faith for two reasons: 1) it’s an empirical method, so to speak; there is no proof in theory that such ‘matching’ will always work; and 2) I believe it’s instructive to think of this relationship as being mediated by faith if only to amplify its anti-polarity with reason. Most of us understand science through faith, not reason. Even scientists who are experts on one thing take the word of scientists on completely different things, instead of trying to study those things themselves (see ad verecundiam fallacy).

Sometimes, such faith is (mostly) harmless, such as in the ‘extreme’ cases of the Bloch sphere and the wave function. It is both inexact and incomplete to think that quantum superposition means an object is in two states at once. The human brain hasn’t evolved to cognate superposition exactly; this is why physicists use the language of mathematics to make sense of this strange existential phenomenon. The problem – i.e. the inexactitude and the incompleteness – arises when a communicator translates the mathematics to a metaphor. Equally importantly, physicists are describing whereas the rest of us are thinking. There is a crucial difference between these activities that illustrates, among other things, the fundamental incompatibility between scientific research and science communication that communicators must first surmount.

As physicists over the past three or four centuries have relied increasingly on mathematics rather than the word to describe the world, physics, like mathematics itself, has made a “retreat from the word,” as literary scholar George Steiner put it. In a 1961 Kenyon Review article, Steiner wrote, “It is, on the whole, true to say that until the seventeenth century the predominant bias and content of the natural sciences were descriptive.” Mathematics used to be “anchored to the material conditions of experience,” and so was largely susceptible to being expressed in ordinary language. But this changed with the advances of modern mathematicians such as Descartes, Newton, and Leibniz, whose work in geometry, algebra, and calculus helped to distance mathematical notation from ordinary language, such that the history of how mathematics is expressed has become “one of progressive untranslatability.” It is easier to translate between Chinese and English — both express human experience, the vast majority of which is shared — than it is to translate advanced mathematics into a spoken language, because the world that mathematics expresses is theoretical and for the most part not available to our lived experience.

Samuel Matlack, ‘Quantum Poetics’, The New Atlantic, 2017

However, the faith becomes more harmful the further we move away from the ‘extreme’ examples – of things we’re unlikely to stumble on in our daily lives – and towards more commonplace ideas, such as ‘how vaccines work’ or ‘why GM foods are not inherently bad’. The harm emerges from the assumption that we think we know something when in fact we’re in denial about how it is that we know that thing. Many of us think it’s reason; most of the time it’s faith. Remember when, in Friends, Monica Geller and Chandler Bing ask David the Scientist Guy how airplanes fly, and David says it has to do with Bernoulli’s principle and Newton’s third law? Monica then turns to Chandler with a knowing look and says, “See?!” To which Chandler says, “Yeah, that’s the same as ‘it has something to do with wind’!”

The harm is to root for science, to endorse the scientific enterprise and vest our faith in its fruits, without really understanding how these fruits are produced. Such understanding is important for two reasons.

First, if we trust scientists, instead of presuming to know or actually knowing that we can vouch for their work. It would be vacuous to claim science is superior in any way to another enterprise that demands our faith when science itself also receives our faith. Perhaps more fundamentally, we like to believe that science is trustworthy because it is evidence-based and it is tested – but the COVID-19 pandemic should have clarified, if it hasn’t already, the continuous (as opposed to discrete) nature of scientific evidence, especially if we also acknowledge that scientific progress is almost always incremental. Evidence can be singular and thus clear – like a new avian species, graphene layers superconducting electrons or tuned lasers cooling down atoms – or it can be necessary but insufficient, and therefore on a slippery slope – such as repeated genetic components in viral RNA, a cigar-shaped asteroid or water shortage in the time of climate change.

Physicists working with giant machines to spot new particles and reactions – all of which are detected indirectly, through their imprints on other well-understood phenomena – have two important thresholds for the reliability of their findings: if the chance of X (say, “spotting a particle of energy 100 GeV”) being false is 0.27%, it’s good enough to be evidence; if the chance of X being false is 0.00006%, then it’s a discovery (i.e., “we have found the particle”). But at what point can we be sure that we’ve indeed found the particle we were looking for if the chance of being false will never reach 0%? One way, for physicists specifically, is to combine the experiment’s results with what they expect to happen according to theory; if the two match, it’s okay to think that even a less reliable result will likely be borne out. Another possibility (in the line of Karl Popper’s philosophy) is that a result expected to be true, and is subsequently found to be true, is true until we have evidence to the contrary. But as suitable as this answer may be, it still doesn’t neatly fit the binary ‘yes’/’no’ we’re used to, and which we often expect from scientific endeavours as well (see experience v. reality).

(Minor detour: While rational solutions are ideally refutable, faith-based solutions are not. Instead, the simplest way to reject their validity is to use extra-scientific methods, and more broadly deny them power. For example, if two people were offering me drugs to suppress the pain of a headache, I would trust the one who has a state-sanctioned license to practice medicine and is likely to lose that license, even temporarily, if his prescription is found to have been mistaken – that is, by asserting the doctor as the subject of democratic power. Axiomatically, if I know that Crocin helps manage headaches, it’s because, first, I trusted the doctor who prescribed it and, second, Crocin has helped me multiple times before, so empirical experience is on my side.)

Second, if we don’t know how science works, we become vulnerable to believing pseudoscience to be science as long as the two share some superficial characteristics, like, say, the presence and frequency of jargon or a claim’s originator being affiliated with a ‘top’ institute. The authors of a scientific paper to be published in a forthcoming edition of the Journal of Experimental Social Psychology write:

We identify two critical determinants of vulnerability to pseudoscience. First, participants who trust science are more likely to believe and disseminate false claims that contain scientific references than false claims that do not. Second, reminding participants of the value of critical evaluation reduces belief in false claims, whereas reminders of the value of trusting science do not.

(Caveats: 1. We could apply the point of this post to this study itself; 2. I haven’t checked the study’s methods and results with an independent expert, and I’m also mindful that this is psychology research and that its conclusions should be taken with salt until independent scientists have successfully replicated them.)

Later from the same paper:

Our four experiments and meta-analysis demonstrated that people, and in particular people with higher trust in science (Experiments 1-3), are vulnerable to misinformation that contains pseudoscientific content. Among participants who reported high trust in science, the mere presence of scientific labels in the article facilitated belief in the misinformation and increased the probability of dissemination. Thus, this research highlights that trust in science ironically increases vulnerability to pseudoscience, a finding that conflicts with campaigns that promote broad trust in science as an antidote to misinformation but does not conflict with efforts to install trust in conclusions about the specific science about COVID-19 or climate change.

In terms of the process, the findings of Experiments 1-3 may reflect a form of heuristic processing. Complex topics such as the origins of a virus or potential harms of GMOs to human health include information that is difficult for a lay audience to comprehend, and requires acquiring background knowledge when reading news. For most participants, seeing scientists as the source of the information may act as an expertise cue in some conditions, although source cues are well known to also be processed systematically. However, when participants have higher levels of methodological literacy, they may be more able to bring relevant knowledge to bear and scrutinise the misinformation. The consistent negative association between methodological literacy and both belief and dissemination across Experiments 1-3 suggests that one antidote to the influence of pseudoscience is methodological literacy. The meta-analysis supports this.

So rooting for science per se is not just not enough, it could be harmful vis-à-vis the public support for science itself. For example (and without taking names), in response to right-wing propaganda related to India’s COVID-19 epidemic, quite a few videos produced by YouTube ‘stars’ have advanced dubious claims. They’re not dubious at first glance, if also because they purport to counter pseudoscientific claims with scientific knowledge, but they are – either for insisting a measure of certainty in the results that neither exist nor are achievable, or for making pseudoscientific claims of their own, just wrapped up in technical lingo so they’re more palatable to those supporting science over critical thinking. Some of these YouTubers, and in fact writers, podcasters, etc., are even blissfully unaware of how wrong they often are. (At least one of them was also reluctant to edit a ‘finished’ video to make it less sensational despite repeated requests.)

Now, where do these ideas leave (other) science communicators? In attempting to bridge a nearly unbridgeable gap, are we doomed to swing only between most and least unsuccessful? I personally think that this problem, such as it is, is comparable to Zeno’s arrow paradox. To use Wikipedia’s words:

He states that in any one (duration-less) instant of time, the arrow is neither moving to where it is, nor to where it is not. It cannot move to where it is not, because no time elapses for it to move there; it cannot move to where it is, because it is already there. In other words, at every instant of time there is no motion occurring. If everything is motionless at every instant, and time is entirely composed of instants, then motion is impossible.

To ‘break’ the paradox, we need to identify and discard one or more primitive assumptions. In the arrow paradox, for example, one could argue that time is not composed of a stream of “duration-less” instants, that each instant – no matter how small – encompasses a vanishingly short but not nonexistent passage of time. With popular science communication (in the limited context of translating something that is untranslatable sans inexactitude and/or incompleteness), I’d contend the following:

  • Awareness: ‘Knowing’ and ‘knowing of’ are significantly different and, I hope, self-explanatory also. Example: I’m not fluent with the physics of cryogenic engines but I’m aware that they’re desirable because liquefied hydrogen has the highest specific impulse of all rocket fuels.
  • Context: As I’ve written before, a unit of scientific knowledge that exists in relation to other units of scientific knowledge is a different object from the same unit of scientific knowledge existing in relation to society.
  • Abstraction: 1. perfect can be the enemy of the good, and imperfect knowledge of an object – especially a complicated compound one – can still be useful; 2. when multiple components come together to form a larger entity, the entity can exhibit some emergent properties that one can’t derive entirely from the properties of the individual components. Example: one doesn’t have to understand semiconductor physics to understand what a computer does.

An introduction to physics that contains no equations is like an introduction to French that contains no French words, but tries instead to capture the essence of the language by discussing it in English. Of course, popular writers on physics must abide by that constraint because they are writing for mathematical illiterates, like me, who wouldn’t be able to understand the equations. (Sometimes I browse math articles in Wikipedia simply to immerse myself in their majestic incomprehensibility, like visiting a foreign planet.)

Such books don’t teach physical truths; what they teach is that physical truth is knowable in principle, because physicists know it. Ironically, this means that a layperson in science is in basically the same position as a layperson in religion.

Adam Kirsch, ‘The Ontology of Pop Physics’, Tablet Magazine, 2020

But by offering these reasons, I don’t intend to over-qualify science communication – i.e. claim that, given enough time and/or other resources, a suitably skilled science communicator will be able to produce a non-mathematical description of, say, quantum superposition that is comprehensible, exact and complete. Instead, it may be useful for communicators to acknowledge that there is an immutable gap between common English (the language of modern science) and mathematics, beyond which scientific expertise is unavoidable – in much the same way communicators must insist that the farther the expert strays into the realm of communication, the closer they’re bound to get to a boundary beyond which they must defer to the communicator.

Scientists make video of molecule rotating

A research group in Germany has captured images of what a rotating molecule looks like. This is a significant feat because it is very difficult to observe individual atoms and molecules, which are very small as well as very fragile. Scientists often have to employ ingenious techniques that can probe their small scale but without destroying them in the act of doing so.

The researchers studied carbonyl sulphide (OCS) molecules, which has a cylindrical shape. To perform their feat, they went through three steps. First, the researchers precisely calibrated two laser pulses and fired them repeatedly – ~26.3 billion times per second – at the molecules to set them spinning.

Next, they shot a third laser at the molecules. The purpose of this laser was to excite the valence electrons forming the chemical bonds between the O, C and S atoms. These electrons absorb energy from the laser’s photons, become excited and quit the bonds. This leaves the positively charged atoms close to each other. Since like charges repel, the atoms vigorously push themselves apart and break the molecule up. This process is called a Coulomb explosion.

At the moment of disintegration, an instrument called a velocity map imaging (VMI) spectrometer records the orientation and direction of motion of the oxygen atom’s positive charge in space. Scientists can work backwards from this reading to determine how the molecule might have been oriented just before it broke up.

In the third step, the researchers restart the experiment with another set of OCS molecules.

By going through these steps repeatedly, they were able to capture 651 photos of the OCS molecule in different stages of its rotation.

These images cannot be interpreted in a straightforward way – the way we interpret images of, say, a rotating ball.

This is because a ball, even though it is composed of millions of molecules, has enough mass for the force of gravity to dominate proceedings. So scientists can understand why a ball rotates the way it does using just the laws of classical mechanics.

But at the level of individual atoms and molecules, gravity becomes negligibly weak whereas the other three fundamental forces – including the electromagnetic force – become more prominent. To understand the interactions between these forces and the particles, scientists use the rules of quantum mechanics.

This is why the images of the rotating molecules look like this:

Steps of the molecule’s rotation. Credit: DESY, Evangelos Karamatskos

These are images of the OCS molecule as deduced by the VMI spectrometer. Based on them, the researchers were also able to determine how long the molecule took to make one full rotation.

As a spinning ball drifts around on the floor, we can tell exactly where it is and how fast it is spinning. However, when studying particles, quantum mechanics prohibits observers from knowing these two things with the same precision at the same time. You probably know this better as Heisenberg’s uncertainty principle.

So if you have a fix on where the molecule is, that measurement prohibits you from knowing exactly how fast it is spinning. Confronted with this dilemma, scientists used the data obtained by the VMI spectrometer together with the rules of quantum mechanics to calculate the probability that the molecule’s O, C and S atoms were arranged a certain way at a given point of time.

The images above visualise these probabilities as a colour-coded map. With the position of the central atom (presumably C) fixed, the probability of finding the other two atoms at a certain position is represented on a blue-red scale. The redder a pixel is, the higher the probability of finding an atom there.

Rotational clock depicting the molecular movie of the observed quantum dynamics of OCS. Credit: doi.org/10.1038/s41467-019-11122-y

For example, consider the images at 12 o’clock and 6 o’clock: the OCS molecule is clearly oriented horizontally and vertically, resp. Compare this to the measurement corresponding to the image at 9 o’clock: the molecule appears to exist in two configurations at the same time. This is because, approximately speaking, there is a 50% probability that it is oriented from bottom-left to top-right and a 50% probability that it is oriented from bottom-right to top-left. The 10 o’clock figure represents the probabilities split four different ways. The ones at 4 o’clock and 8 o’clock are even more messy.

But despite the messiness, the researchers found that the image corresponding to 12 o’clock repeated itself once every 82 picoseconds. Ergo, the molecule completed one rotation every 82 picoseconds.

This is equal to 731.7 billion rpm. If your car’s engine operated this fast, the resulting centrifugal force, together with the force of gravity, would tear its mechanical joints apart and destroy the machine. The OCS molecule doesn’t come apart this way because gravity is 100 million trillion trillion times weaker than the weakest of the three subatomic forces.

The researchers’ study was published in the journal Nature Communications on July 29, 2019.