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How cosmic is the cosmos?
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Ever since Heisenberg and Tagore, physicists have flirted with Eastern philosophy. Is there anything in the romance?
here is a story that the Buddha was once addressing his sangha, the monastic community who had gathered around to listen to him preach, when one of his bright young followers posed a series of questions. What, he asked his spiritual leader, is the origin of the Universe? Is the cosmos infinite? Is it eternal, or did it have a beginning?
After the student had finished, he looked up to the Buddha to hear his pearls of wisdom, but the older man was silent. Eventually, the young monk left, disappointed, only to come back the next day with the same queries. Once again, however, the Buddha remained quiet. On the third day, the young man returned and said in frustration: ‘I have asked you these questions twice. If you don’t know the answer, then admit that you don’t know. If you do know but you think I won’t understand, then just say that, but I urge you to try to explain. If, however, you stay silent, then I’m going to leave and not return.’
Finally the Buddha replied, saying gently but firmly that these are simply not issues to which the Buddha speaks. ‘What I address is human suffering and liberation from this suffering,’ he said. ‘Nobody asked you to come here, and you are always free to leave.’
This tale was recounted to me by Abhay Ashtekar, a physicist at Pennsylvania State University who, over the past two decades, has delved deeply into meditative Buddhist philosophy. In tandem, however, he has investigated precisely those puzzles about the origins of the Universe and the nature of time that the Buddha deemed irrelevant. Unlike the Buddha, Ashtekar sees profound resonances between his spiritual quest and his scientific one. Though his theories of the early Universe are not directly based on Buddhist concepts, Ashtekar has inadvertently uncovered some surprising similarities, both in the methods of his scientific and spiritual practice and in some of the answers that they can offer about the nature of physical reality.
shtekar is not alone in connecting modern cosmology with ancient non-Western thinking. There is a long tradition devoted to uncovering parallels between the two. Werner Heisenberg, one of the founding fathers of quantum mechanics, had a meeting on the issue with Rabindranath Tagore, the Indian poet and philosopher, in 1929. Later, the Austrian physicist Fritjof Capra popularised the connection between modern physics and mysticism through his groundbreaking book, The Tao of Physics (1975).
The discussion has gone on ever since. I partook in 2014, while researching my book, A Big Bang in a Little Room (2017), about experiments on recreating the origins of the Universe in the lab. Not only did I meet with Ashtekar at Penn State but also with his kindred spirit, the cosmologist Andrei Linde, at Stanford University in California. Linde had just returned from giving a series of guest lectures at the University of Hamburg in Germany on the philosophical implications of ‘quantum cosmology’, the discipline that applies the rules governing the micro realm – quantum theory – to the study of how the Universe evolved in its infancy, when it was still growing from a tiny seed.
‘The climate was to ignore religion, so I was, with my strange philosophy, the most religious person around’
In those talks, Linde had pointed to a harmony between cosmology and the ancient Hindu philosophical school Advaita Vedanta, which posits a unity between the eternal cosmos and the self. Specifically, he found resonance between Advaita Vedanta and theories developed by modern physicists to explain why time’s arrow points in one direction, inexorably marching us from cradle to grave. Ashtekar, independently, was challenging the conventional view that our cosmos was born at the Big Bang, replacing it with a model of an eternal universe that once contracted and is now expanding again. He even began to ponder whether it might be possible to construct a scientific model aligned with non-Western philosophies, in which individual human consciousnesses are embedded in a larger communal consciousness that pervades the Universe.
Mentioning spiritual texts in the same breath as physics is not fashionable; the danger is you will come over as both a wannabe guru and a flaky physicist. Linde recalls his reticence before the Hamburg meeting: ‘I was so scared about that, about talking to them about reality, because this is the least understood thing about quantum mechanics and quantum cosmology.’ Born in Moscow when Russia was still in the Soviet Union and religiosity was taboo, Linde had no formal religious upbringing. Today he identifies as an atheist, albeit one who grew up with a taste for big theological questions, voraciously reading both philosophy texts and science fiction for thoughts about the nature of the self and consciousness. ‘The climate was to ignore religion, so I was, with my strange philosophy, the most religious person around,’ Linde says, laughing.
Linde is now most famed as one of the co-founders of inflation theory, which he developed while in Russia in the 1980s, and which posits that the early Universe went through a rapid period of expansion, racing outwards faster than the speed of light, for a fraction of a second after the Big Bang, before slowing to a more sedate pace of growth. That idea, though not yet fully confirmed, has passed pretty much into mainstream cosmology. But while cosmologists largely agree about what happened just after the Universe’s birth, they are still perplexed about the physics that occurred before inflation, at the Big Bang itself, when – according to the conventional view – the cosmos came into being. It was an early attempt to unpack this birthing moment that raised paradoxical puzzles about the nature of time, calling its very existence into question – and echoing non-Western philosophy long before cosmologists entered the fray.
The so-called ‘problem of time’ in physics arose back in the 1960s, as physicists grappled with deriving a mathematical description of the Universe’s birth. The standard story is that the cosmos exploded out of an infinitely small, infinitely dense point, or ‘singularity’ at the Big Bang, creating both space and time. Before the Big Bang, there was nothing, no time and no space. The trouble is that our current understanding of physics does not allow us to say much about what singularities are, or what happens within them.
On the one hand, physicists feel that since singularities are tiny, they should be beholden to the laws of quantum physics, which governs the behaviour of small objects. Quantum theory provides a well-developed mathematical framework for describing what happens to small things such as atoms, electrons or photons in lab experiments. This includes a number of oddball characteristics they display that we do not usually see in everyday life; for instance, two quantum objects can become inextricably linked, or ‘entangled’ with each other, influencing each other over great distances.
Another weird, but central tenet of standard quantum physics is that a modicum of unpredictability is woven into reality, so the fate of an individual particle cannot be calculated with absolute certainty in advance. By using an equation developed by the Austrian physicist Erwin Schrödinger in the 1920s, physicists can work out the probability of a particle behaving in one way or another when it is monitored in the lab – whether it will travel in this direction or that, or be found here or there. And when multiple experiments are carried out on many thousands of similar particles, the equation’s predictions for the proportion that will behave a certain way are stunningly accurate. At the heart of the equation is a ‘wavefunction’ – the mathematical description of the tiny object in question, which encompasses the myriad of many possible outcomes that could manifest when the object’s properties are measured in an experiment.
Linde and many others think that the ultimate description of the Universe can be found by applying quantum rules to the newborn Universe. The catch is, however, that unlike small lab particles, our infant Universe was cosmically heavy, containing within it the seeds of all the stars, galaxies and planets we see today. Massive cosmic objects such as stars and planets are not usually subject to quantum laws; instead, their motion is calculated using Albert Einstein’s general theory of relativity, also developed in the early 20th century. In Einstein’s framework, the Universe is pervaded by a four-dimensional fabric that bends around masses, knitting together space and time. This warping creates dips and contours in spacetime around more massive bodies, such as stars, channelling planets to orbit around them. In a now famous adage, the physicist John Wheeler at Princeton University succinctly explained: ‘Spacetime tells matter how to move; matter tells spacetime how to curve.’
The trouble for time came when physicists attempted to put these two cornerstones of modern physics – quantum theory and general relativity – together. In the 1960s, the US physicist Bryce DeWitt, inspired by Wheeler, defined a quantum wavefunction for the infant Universe, and set out an equation that combined Schrödinger’s and Einstein’s mathematics in an attempt to explain how the early cosmos evolved through time, governed by both quantum physics and relativity. It is now known as the Wheeler-DeWitt equation, even if, as Linde says: ‘Wheeler did not derive it and DeWitt did not like it. It is a really strange, esoteric equation.’
‘People would get younger, broken glass would become glued together again’
The weirdness Linde refers to that discomfited DeWitt was that, while quantum and relativistic equations each individually contain a variable that marks the passage of time – an essential component if you want to use your equation to calculate how systems evolve – when DeWitt brought the equations together, the time variable cancelled out the Wheeler-DeWitt equation entirely: his equation for the wavefunction of the Universe was telling him that the cosmos does not evolve, or change in time, at all. It should not expand out from a small singularity, seed stars, galaxies, planets or people. It should just be frozen. ‘That’s a theorem,’ Linde says emphatically: the problem of time is that it is an illusion, and there is no such thing as time, at the fundamental level.
And yet, time passes… oh, time passes. Seasons change, years roll by, we live, we age, and we die. Things happen – even though the Wheeler-DeWitt equation seemed to say that they could not. ‘Now, you may think that this is a kind of a joke, and that wise people would find a solution to that,’ says Linde.
But when ‘wise people’ first tried, matters got only more confusing. Linde recalls his friend and colleague the British physicist Stephen Hawking visiting him in Russia in the mid-1980s, and telling him of his attempt to make sense of the prediction from the Wheeler-DeWitt equation that nothing could happen in the Universe overall. Hawking argued that since the evolution of the wavefunction of the Universe apparently did not depend on time, it must depend instead on how big the Universe is.
Astronomical observations made in the 1930s told us that neighbouring galaxies are receding away from us, and our Universe is currently expanding. Hawking speculated that this growth might come to an end; at some point, he said, the Universe could reach a maximum size and then begin contracting. Since, in his proposal, the Universe’s evolution depends only on its size, as the cosmos shrinks back down, all the cosmic changes that had happened when the Universe was growing would rewind and be unmade. This way, Hawking posited, the overall wavefunction would ultimately be unchanged.
Linde baulked at Hawking’s suggestion: instead of humans experiencing first birth, life and then finally death, time would turn back as the Universe contracted, and ‘the dead would stand up from the graves’, he scoffs. ‘People would get younger and younger, broken glass would suddenly jump from the floor and become glued together again, and dinosaurs will reappear on the Earth.’ Though physicists wouldn’t admit that this was explicitly the consequence of such a theory, ‘because it is too obviously ridiculous’, that, Linde insists, was the physical upshot. ‘You could call this the greatest blunder of Hawking’s life.’
Anyone who has met Linde will know that he is a man with great a passion for his physics; in fact, he feels such ‘blunders’ and missteps in the development of his corner of cosmology viscerally. As a young researcher in Russia, he hit a temporary intellectual roadblock with the development of inflation theory (he, and others, had been unable initially to work out a mechanism that would explain how the Universe would stop inflating at a breakneck, faster-than-light speed – as ours has, today expanding at a much more modest rate). While struggling with the mathematics, before eventually solving the conundrum, he fell into a funk. It was during this year of emotional frustration that he turned to the Advaita Vedanta, the philosophy that emphasises oneness between the self and the Universe.
‘I should not jump into Indian philosophy, which I am not exactly an expert in,’ says Linde, cautiously. Rather than making stark pronouncements about physics based on the readings of his youth, he simply wants to point out the similarities that struck him between the problem of vanishing time arising from the Wheeler-DeWitt equation and the Indian conception of time. In contrast to Judeo-Christian-Islamic notions of a God as a superior being – crudely caricatured as ‘a man with a beard’, notes Linde, or perhaps thought of as a powerful, but external, force of nature – there is the more Eastern abstraction of God as absolute perfection encompassing everything. This perfection cannot change in time because if it did, then it would either have to have been less perfect in the past, or become less perfect in the future.
‘And then you think about the wavefunction of the Universe, which is absolute perfection, which does not depend on time, which embeds everything – everything including observers,’ says Linde. Indian philosophers two millennia ago were faced with the same paradox as modern physicists: how can an unchanging reality hold within it observers that undergo change? The ancient philosophers’ solution, Linde notes, is that time ticks for humans because we have ‘cut ourselves out from God’. Once we do so, then from our individual perspective, experiencing reality as a separate being, the rest of the Universe starts to tick, evolving in time relative to each human being as an observer.
So far, so mystical. But, perhaps surprisingly, a similar solution to the problem of time in physics was proposed in 1983 by one of Hawking’s students and later collaborator, Don Page, now at the University of Alberta in Canada – without any consideration of Hindu teachings. Page and his colleague Bill Wootters of Williams College in Massachusetts, turned instead to a well-established quantum phenomenon known as ‘entanglement’, which has been demonstrated many times in the lab. Here, the very laws of quantum physics hold that some particles are connected together no matter how far they are pulled apart; indeed, in experiment after experiment, measurements carried out on one always instantaneously influences the properties of its entangled mate.
Page and Wootters pondered what would happen if you took the whole unchanging Universe and chopped it into two entangled pieces. They calculated that an observer, a human consciousness, say, or maybe even an inanimate recording device, sitting in one entangled part would monitor the other part of the Universe evolving relative to its own. The crucial insight was that the presence of an observer on one side starts the clock running on the other side. ‘How do you know that people are dying and being born? You first look at them,’ says Linde, slapping his hand to his knee, for emphasis. ‘That is the key: there must be somebody who looks.’
Importantly, Page and Wootters calculated that when both divided parts of the Universe are monitored in conjunction by some imagined superobserver, the evolution within the individual parts should counterbalance, so that from an external god’s-eye view there would be no evolution in the cosmos as a whole. The wavefunction of the entire Universe would remain timeless, just as DeWitt had predicted, solving the problem of how an unchanging Universe can house time.
‘As long as you do not have an observer, the arrow of time doesn’t exist’
Though this was just a mathematical speculation, it has since been tested in the lab, in an extremely pared-down version of the Universe, containing a meagre two particles – not a complex enough model system for anything too exciting to happen, perhaps, but with just enough pieces to test the theoretical claim. In 2013, the quantum physicist Marco Genovese at the Istituto Nazionale di Ricerca Metrologica in Italy and colleagues used two photons to represent the two sides of a divided microcosmos. The photons were both polarised, meaning that each one vibrated along its length. The team entangled the pair of photons in such a way that, if the polarisation of the first photon was measured to be vibrating up and down, its entangled partner would instantaneously be forced to vibrate from side to side.
The photons also served as mini clocks because, in addition to being polarised, they also each literally rotated at a constant rate, like the hands on a watch. The team could thus, in principle, measure how time passed within each half – if time did indeed pass – by monitoring how far the photon in that half had rotated. Technically, the act of measuring one photon’s rotation causes the experimenters to become entangled with it themselves, so in essence the physicists then became part of the first photon’s side of the micro-Universe. From this vantage point, they could then monitor how the second photon – the second half of the Universe – evolved, by measuring how far it had rotated, relative to the first photon. By doing this, the team was able to confirm one part of Page and Wootters’s proposition, that if you are housed within one part of the Universe, you will be able to view changes in the other half.
The trick was then to repeat the experiment, but this time from the god’s-eye viewpoint that remained external to both halves of the microcosmos, or both photons. In that case, the team could not allow themselves to become entangled with either photon; they were allowed only to measure the joint state of both photons, taken together as a pair. That meant that they could no longer see any relative rotation between the two photons, or the passage of time. All they could do was confirm that the two photons were permanently polarised in opposing directions – up-and-down and side-to-side – with this eternal embrace never changing. Research confirmed that when viewed from outside, their two-photon Universe, as a whole, was frozen in time.
‘So as long as you do not have an observer, the arrow of time doesn’t exist, and the paradox doesn’t exist,’ Linde explains. ‘But as soon as you have an observer, the Universe becomes alive. This duality between you and the Universe is part of the whole package.’ Though not a religious man, this has inspired him to riff about the fate of people after death; perhaps, as some non-Western philosophies suggest, their individual consciousnesses become unified with the wholeness of the Universe, once more.
Nobody is suggesting that progress in physics will be found by mining ancient Hindu scriptures directly for inspiration. Nor, indeed, that scholars of the Advaita Vedanta had some privileged insight into scientific truths. Yet, curious resonances between the philosophical ideas read in one’s youth, and theoretical speculations that arise from the physics of today can sometimes make the latter seem more compelling. Perhaps that is why Linde was more intuitively drawn to Page and Wootters’s solution to the problem of time than to Hawking’s.
More so than Linde, Ashtekar has spent many years practising meditation, and he is unabashed about the interplay between his scientific thinking and his spirituality – the parallels between his two worlds are poetic and profound. With colleagues, he has proposed an alternative to the conventional picture, in which time is created in the explosion of the Big Bang, arguing instead that the cosmos is eternal, and removing the need for those pesky infinitely small and dense singularities that physicists have spent decades struggling to explain. But he has also thought about ways to bring the two modes of thought – spiritual and scientific – together more explicitly, when considering the nature of consciousness.
Ashtekar was raised a Jain – an Indian religion that eschews the idea of a deity, and places emphasis on avoiding cruelty to humans and animals, as the soul moves through cycles of reincarnation. As a boy, his family moved between various small towns in India following his father’s postings in the civil service, and Ashtekar says that in some of the more provincial areas it was easier to find books on Vedantic philosophy than on physics. His childhood travels also exposed him to a variety of communities, and he read voraciously on Hinduism, Buddhism and Chinese Taoism, alongside his scientific studies.
Ashtekar’s passion for understanding the ‘inner world’ of consciousness, as well as the external physical world, continued when he moved to the US in the 1970s. While enrolled in graduate study in physics at the University of Texas in Austin, Ashtekar also took a year of classes with the renowned Indian philosopher Raja Rao, debating the merits of Hinduism compared with Buddhism. Eventually, his desire to unravel Einstein’s spacetime fabric won over, and took him to the University of Chicago, to study general relativity with the physicist Robert Geroch, an expert on singularities.
At some point, in the past, the cosmos contracted, and then bounced out again
For Ashtekar, it was not enough to just accept that the Universe is pervaded by a four-dimensional spacetime fabric. He wanted to know how that fabric was stitched together, believing that the answer held the key to explaining how general relativity and quantum theory can come together on the tiniest scales. Developed with others – most notably the physicists Carlo Rovelli of the Centre de Physique Théorique in France, and Lee Smolin of the Perimeter Institute for Theoretical Physics in Canada – Ashtekar’s speculative theory is known as ‘loop quantum gravity’ and, as he explained to me at his office at Penn State, sounds almost too trivial to be true. Ashtekar was wearing a grey shirt and started to pull at its threads to illustrate his thinking. He remarked that when it is viewed from afar, the shirt appears to be cut from one continuous smooth material; viewed up close, however, you can see the threads from which it is woven. Similarly, he argues that if we had powerful enough microscopes to zoom in on Einstein’s fabric, we would see that it is knitted together from ‘loops’ – hypothetical threads of energy that manifest through quantum processes.
There’s precedent for the idea that such threads could pop from seemingly nowhere in conventional physics. For instance, physicists have a quantum description for light, which states that light particles, or photons, are actually excited bundles of energy that rise up from a background electromagnetic field – like water waves swelling up from an otherwise still ocean. What’s more, the unpredictability of quantum theory also extends to the seemingly empty vacuum, so you can never say with certainty that is it truly empty. That enables pairs of ‘virtual photons’ to be created fleetingly from apparently empty space, before they recombine and disappear. Ashtekar’s proposed loops take these established quantum concepts a step further, spontaneously manifesting as agitations of a hypothetical field of ‘quantum geometry’, which he posits exists everywhere, eternally. These loops then link together to create a web that weaves together spacetime.
At first, it might seem as if he has just replaced one mysterious fabric that pervades the Universe – Einstein’s spacetime – with an equally enigmatic web of quantum geometry and loops. But Ashtekar’s theory has another nifty feature: it demarcates a minimum loop size below which the loops cannot knit together. That, in turn, sets a minimum size below which spacetime, itself woven from loops, cannot be squeezed. This means that, according to the loop quantum gravity picture, the Universe could never have been squashed into a tiny singularity, even at its birth.
To find out what might have happened at the Big Bang, according to his loopy framework, Ashtekar and colleagues created a computer simulation of the Universe and then wound the clock back roughly 13 billion years, to the time when the Big Bang is thought to have occurred. At first, things proceeded in the conventional way: as time reversed, the cosmos became smaller and smaller. But just before reaching the point where conventional physics puts the Big Bang’s infinitely small singularity, the cosmos shrunk down to a certain minuscule but finite size, and then began to expand outwards again. Ashtekar argues that this indicates that our cosmos had no beginning – no birth at a Big Bang singularity – but instead has always existed. At some point, in the past, he says, the cosmos contracted, and then bounced outwards again, and we now live in that expanding phase.
Ashtekar says that the parallels between his theory of loops and the ancient scriptures – both describing a universe cycled through phases of creation and destruction – are merely coincidental, if pleasingly consonant. But there are other areas where he makes more explicit links between his physics and spirituality.
Over the past decade or so, Ashtekar has become a more committed adherent of Buddhism; following the Vipassana school, he has taken part in intense 10-day meditations, during which he is banned from speaking and reading. Isolated from the world, he strives to reach a state of consciousness ‘beyond thought’, challenging the intellectual focus and diligence of the physicist. ‘From my intellectual life I had the inner pride of being able to concentrate for hours,’ he says. ‘When I am working on something, I completely lose track, sometimes to my detriment.’ But this paled against the strength of mind needed to sustain deep meditation. Ashtekar felt like a helpless child. ‘They do say that the first time you do it, it is like “surgery for the mind”, and it does have very, very deep cleansing effect on your consciousness,’ he says.
Inspired by his meditative practice, Ashtekar is training a scientific eye on other aspects of Buddhist philosophy. The practice teaches of a cycle of personal reincarnation broken by reaching enlightenment, or nirvana. Ashtekar has been pondering whether it might be possible to develop a physical model of consciousness that chimes with this. His viewpoint – similar to the concepts espoused by the Advaita Vedanta school that Linde was fascinated by – is that there is a universal field of consciousness, embedding our individual selves.
The best proof will not come from a lab, but from people trying deep meditation for themselves
Harking back again to quantum physical description of photons as excitations of an electromagnetic field, and his own proposal that loops are lumps of energy thrown up from a background sea of quantum geometry, Ashtekar describes our individual consciousnesses as agitations in this communal ocean. As we experience the daily trials of life as well as profound suffering, we are pulled from this calm background like angry turbulent waves. Meditation, Ashtekar posits, quiets our minds, enabling us to sink back into a still sea. ‘Perhaps nirvana is just the ground energy state’ – the lowest energy state – ‘of this consciousness field,’ Ashtekar speculates.
This is not simply a metaphor for Ashtekar, but a scientific proposal, though one that he has yet to rigorously develop and for which there is, for now at least, no means to test. This does not dismay Ashtekar, who points out that way back in 1916 Einstein predicted that ripples in his spacetime fabric could potentially be observed. It took another century for physicists to detect these ripples, or gravitational waves, which were set off when two black holes collided long ago.
The best and most convincing proof, Ashtekar argues, will not come from a lab test, but from people trying deep meditation for themselves. The effects can be so profound, he says, they can pull you deep into the inner world, till you lose touch with the external world. ‘You lose your motivation, or the fire in your belly,’ Ashtekar says. Fearing that he might inadvertently destroy his drive to study physics, Ashtekar now just dips into meditation briefly at times of stress, to bring him ‘basic joy’.
Both Ashtekar and Linde concede that many scientists will raise their eyebrows at attempts to bring together science and spirituality, worrying about the dangers of dragging physics into mysticism. Scholars of non-Western philosophy will be equally wary about the merits of picking and choosing which aspects of their teachings to use as a lens through which to view cosmology. Yet spiritual lessons do sometimes inform the speculative ideas to which physicists might be drawn intuitively. When faced with rival physical theories, instinct can play a role in deciding which sits better with your taste, even for professional scientists. As Linde puts it, the theories that you pursue with a passion are not the ones that seem right based merely on mathematical grounds, but must also ‘tell something to your heart’.