‘Only by treasuring that we are stewards of planet Earth, and the finitude that comes with it, will be able to avoid humanity pitting its many powers against itself.’
On the Origin of Time is an important book in two respects: it develops our thinking about the nature of the universe and it calls for a fundamental change in the way that humans are living on this planet.
Firstly, the nature of the universe. Hopefully, you are familiar with the wave-particle duality of light. If not, very short version: a photon has the properties of both a wave and a particle. You can make light behave like a wave and see, for example, the interference patterns it makes when it ripples through two holes. Just as with ordinary waves, when streams of light meet they reinforce each other or cancel each other out. The other aspect of light is that it is a particle and you can measure it as a stream of individual pulses as it passes by a detector. Light has both those qualities simultaneously, making it something very different to waves of water or particles of sand, something very hard to imagine and outside our usual experience. Well this book explains a new duality that has been explored in the last twenty years: that between the universe we are familiar with and a boundary filled with quantum information that projects the universe as a hologram: quantum holography.
The kinds of holograms we normally come across are three dimensional images created by projections from information recorded in two dimensions. Recent developments in physics argue that you can create a three-dimensional boundary hologram that projects the four-dimensional universe as we know it. This holographic revolution, says Hertog, ‘ranks among the most important and far-reaching discoveries in physics of the late twentieth century.’
There are a lot of implications to work out from this idea, but one of the most interesting concerns time. The boundary hologram does not feature time: time only emerges as you make the transition from the boundary to the universe we are used to.
I should pause here. That last paragraph needs a lot of unpacking. For a start, I need to make clear that when I write that the universe is a hologram, I don’t mean that it’s a rather flimsy, ghostly affair like a laser hologram. No, it’s the same universe we are familiar with. You can shape it, taste it, hear it, rub up against it and feel it rub back. The new idea is not that our experience of the universe is different, but that we can now understand that we are only accessing it from one side of a duality. It’s a bit like only ever having encountered light as a wave but finding out that it is just as valid to experience it as a sequence of particles.
Returning to the question of time: what are the implications of the fact that the boundary with holographic information is without a dimension of time? Well, I found that reading about this forced me to try to do something very difficult, which is to access the universe as being a time-not-time duality. Viewed from within the projection, it feels like there is time: there is causality and a progression from the Big Bang to where we are today. But that’s only a partial grasp on the situation. Viewed as a hologram, the universe is timeless and if you could translate the information from the boundary where the hologram is described, you could see the entire history of the universe. We are immersed in time and simultaneously in a timeless state.
If you are like me, you will have been brought up in an empirical philosophical tradition that is repelled by the thought of something being itself and something quite different at the same time. Pudding is pudding and don’t be telling me anything else. Either there is time, or there isn’t. How can you have a universe that’s a time-timeless one? Like a battery-driven toy bashing repeatedly into a wall, however, such an insistence on travelling only in straight-line paths misses the fact that the toy is in a maze and it won’t get out via straight lines.
Again and again in the history of thought, apparently insuperable clashes of rival theories have been resolved by adopting a wider perspective that reveals that they were only portraying part of a deeper picture. Rest turns out to be best understood as a special form of motion; Newton’s laws are best understood as a particular case within relativity.
In principle, therefore I’m willing to believe that there is a perspective for understanding the universe from which one can appreciate that the full picture involves both time and timelessness. In fact, this thought is rather appealing to me, exciting even (what effect would it have on your behaviour if you thought that everything you did was preserved somewhere?). The book doesn’t offer any of the maths behind quantum holography. We’re told that ‘it requires a sophisticated mathematical operation’ to decipher even a constrained physical universe from a holographic surface description, which means the reader only gets the gist of the argument. Given that this is a bit ropey and there is currently no explanation of where such a surface might exist, the book’s claims about the holographic nature of the universe might be a bit premature.
As an aside, a certain amount of the book is taken up with explaining how impressive was the mind of Stephen Hawking and how Hawking and the author anticipated many of the recent developments in physics. I think that in places the pages of the book are stained by the discolouring marks of our current celebrity culture and proprietorial approach to ideas, which is unfortunate because the core ideas in this book are valid and important.
The book is at its most persuasive with regard to black holes. One crucial paradox that this new approach resolves is that arising from black hole radiation. In 1974, Hawking demonstrated that black holes radiate energy. By classical general relativity, black holes destroy all information falling through the event horizon, infinitely. In contrast, by Hawking’s formula, black holes have a complex inner life and a finite capacity to absorb information. This capacity is massive – the black hole at the centre of the Milky Way can store 1080 gigabytes (the entire corpus of data currently stored in Google’s servers could fit in a black hole the size of a proton) – but it is finite and a black hole will gradually evaporate.
Quantum Holography and the Black Hole Information Paradox
The fact that black holes can radiate themselves out of existence creates a major paradox. What happens to all the information that fell into the black hole? If it is gone forever, this violates a fundamental and well understood feature of quantum physics, which is that the wave function of any system has to preserve information. This is connected to the probabilistic nature of a quantum event. The sum of the probabilities has to be one. Suppose we’re trying to pin down a subatomic particle’s position. Quantum physics gives us a formula for doing this that is probabilistic. There is a chance of finding the particle at position x. And if we add up the probabilities for all the possible x’s, this has to come to 1 since the particle is definitely somewhere.
The headache that Hawking Radiation posed for quantum physics is that if a black hole has evaporated but in the course of its life it has destroyed all the information that crossed into it, then the universe has a net loss of information. All the probabilities for the position of a particle no longer add up to 1. And this makes a nonsense of the laws of physics and quantum physics in particular.
What about if the black hole radiation contained the missing information? That would work very well for keeping quantum mechanics consistent across the universe. The problem was that for a long time – two decades – the maths of Hawking Radiation said that the emitted radiation was featureless: once a black hole fully evaporated, all that was left was a cloud of thermal radiation with no history.
The breakthrough of quantum holography allowed a solution to this paradox. You can describe a black hole using a boundary hologram and by doing so, the life cycle of the black hole that is so complex and paradoxical in the universe as we experience it turns out to be very simple. As the projection of a boundary hologram a black hole is not much more complex than the heating and cooling of a plasma of subatomic particles. These fairly ordinary clusters of particles can be described with wave functions that preserve information. So by appreciating the duality of black holes – that they are simultaneously relativistic objects that are destructive of everything and yet obey information-preserving quantum laws when understood as holograms – you can, in principle, conclude that the black hole information paradox is only superficial.
In the last few years, a model has emerged of how, more precisely, the information inside a black hole can be preserved. Subatomic particles that arise as particle-antiparticle pairs are entangled and if you can measure one you simultaneously learn about the other. If one of the pair falls into a black hole, in theory we can still know a great deal about it by measuring the partner particle. Entanglement between the inside and outside of a black hole can be described mathematically by a wormhole.
Relativity and Quantum Physics
Another huge discrepancy in science addressed by the idea of the boundary hologram projecting the universe is the paradox that relativity and quantum mechanics are incompatible. Relativity is the science that traditionally informs our picture of the universe, especially with regard to large objects and gravity. The domain of quantum mechanics is typically the tiny realm of subatomic particles. The two theories are both enormously successful and yet they aren’t consistent with each other and this shows up when you consider black holes or the Big Bang, where quantum effects are massively magnified to become of fundamental importance at the macro level, which is supposed to be relativistic.
Quantum holography offers a standpoint to resolve the crisis, again by allowing us to appreciate that there is a duality at play, where it is not either / or but both. The quantum description of the boundary hologram gives rise to the relativistic content of the universe with planets and stars. Again, like the treatment of light as both wave and particle, we need to understand the universe in a totality where it is simultaneously both. As Hertog puts it, ‘Gravity and quantum theory need not be water and fire but can be like yin and yang, two very different yet complementary descriptions of one and the same physical reality.’
You can see this is an ambitious book. It tackles the deep challenges at the boundaries of our knowledge and any theory that offers a breakthrough on the decades-long problem of making relativity and quantum theory compatible would be worth reading for that topic alone.
Quantum Holography and the Origins of Time
What does quantum holography reveal with regard to the origin of the universe? It shows a vast emptiness, where you have scrolled so far out and blurred the resolution of the information to the point that there is just one entangled particle-antiparticle pair. This translates as the pre-origin of physics.
‘One ventures into the past in holographic cosmology by taking something like a blurred viewpoint on the hologram… It is like zooming out… A hologram of an expanding universe inscribes the far past in qubits spanning huge distances in the surface world… in effect, eventually, one runs out of entangled bits. This, then, would be the origin of time.’
Note how different this is to the classical query about what existed before the Big Bang. From within the universe and especially within the flow of time, it seems to be a reasonable question to wonder what happened before the Big Bang. By treating the universe as a quantum hologram, however, we appreciate that all the laws of physics themselves, including those concerning time, are emergent. It is not like there is a giant clock standing outside of the universe; nor fundamental laws that when we apply them to the initial conditions will allow us to model the development of the universe. What lies beyond or before the universe? We can’t say because there is nothing to speak with: there is no information on the hologram about this.
Note too how in the cosmological holograph there is no sign of multiple island universes. No multiverse. The idea that the Big Bang occurs momentarily after our universe has dropped away from a seething stream of chaotic energy has many advocates. The main appeal of this version of the multiverse argument (universes are constantly bubbling from primordial froth) is that it allows for a selection process to arrive at a universe where life is possible, despite that being extremely unlikely. But as Hertog points out, such a multiverse model requires us to believe in a place of infinite information whereas a boundary hologram is finite and for me there’s something more persuasive about that.
Moreover, On the Origin of Time has its own answer to the challenges of the Anthropic Principle (the laws of this universe are perfect for the evolution of life. A tiny change to any of the physical constants, however, would have resulted in very different universes. So how has this perfect universe come about?). In order to understand the hologram solution to the Anthropic Principle, we also have to understand the difference between this new book and the ideas Hawking put forward in A Brief History of Time.
A Brief History of Time
‘I now object to the idea that the universe has a global classical state. We live in a quantum universe so it should be described by superposition of histories à la Feynman, each with its own probability… I think that a proper quantum outlook will lead to a different philosophy of cosmology in which we work from the top down, backward in time, starting from the surface of our observations.’
One of the strangest features of the quantum world is that observation is integral to understanding it. If you had a conventional Western education like mine, then science is taught as the discovery of laws of nature that are always exact, regardless of whether anyone or anything is watching. In the quantum world, a particle is in a superposition of possible positions and velocities, described by a wave function, until one of these is fixed by an observation (the other one then, necessarily, becoming unknowable). The observer doesn’t have to be human or sentient. Any record of quantum events is a form of observation, so when a quartz crystal preserves the path of a subatomic particle that passed through it, the crystal acts as an observer.
The quantum universe does not branch without observation and this is true for fixing time as well as for space. Suppose a beam of light from a very distant quasar takes billions of years to reach us and that on the way it encounters a galaxy, which bends the light along one of many possible pathways to our telescopes. This really does happen and is called gravitational lensing. Only when we observe the light do we find out which route it actually took, which fragment of the quantum universe we are in. Until then, it is in a wave function travelling through all possible routes.
This is what Hawking and Hertog mean by ‘top-down’ cosmology. They believe the universe is a quantum universe and that even the distant past, when no observers existed, can be selected by observation today. Note that this is not at all the same as time travel. Nothing is being sent into the past. It’s more like an archaeologist finding a new type of bone and therefore being able to explain the path that evolution took. Except that for the archaeologist, the past has already been observed (by environmental events a fraction of a second after the gene mutation that gave rise to the new creature) and the branch of the universe we live in fixed long before their discovery of the bone. In the example of light crossing space for billions of years, the difference with archaeology is that the quasar light is still in a state of superposition until we switch on the telescope. The history of quantum activity isn’t fixed until an observation has taken place; current and future events select the past.
Since 2015, experiments have confirmed that the history of the motion of subatomic particles is fixed by observation and that before the observation they are in a quantum state. As Andrew Truscott put it after conducting an experiment with atoms of helium, ‘It was only when they were measured at the end of the journey that their wave-like or particle-like behaviour was brought into existence.’
This is an elusive but crucial point. It is perhaps best understood with a simple game designed by John Wheeler, a physicist whom Hawking and Hertog came to value very highly for his pathbreaking ideas in the 70s and 80s. The game is like Twenty Questions and you have to guess the item the other players are thinking of, with them giving Yes/No answers. The other players, however, haven’t agreed on what that item is. The only rule they have to obey is that their answer (Yes or No) must be compatible with the previous answers. After several questions, the possibilities are more and more constrained until the game converges on an answer that might be extraordinarily unlikely at the start (what are the odds, for example, that the result would be a black pawn from a chess set made in 1928?) but which is consistent. Notice how the questions being asked by you make all the difference to where the game ends up. If you ask, ‘is it something to do with chess?’ and the person whose turn it is to answer says ‘yes’, that creative intervention by you narrows down the possible results considerably.
In the same way, when we make observations about the universe, we are assisting in creating the answer. Hawking once told Hertog, ‘The history of the universe depends on the question you ask.’ We live in a participatory universe.
Wheeler drew an image to help make this insight clearer. The universe develops to the point where there are observers and these observers fix the past, including the distant past long before any observers exist.
If we imagine the line in the Wheeler diagram as the outcome after a quantum field has been fixed by an observation, then we get to the top-down cosmology of Hertog and Hawking.
Resolving the Anthropic Principle with Quantum Holography
Taking a top-down, observer inclusive, approach to the conundrum of the Anthropic Principle makes it a non-paradox. From a classical perspective it seems extraordinary that the laws of physics should have, at every choice, taken the path that resulted in a life-compatible universe. But if we are only now switching on the telescope and observing the fragment of the wave function that we live in, then it necessarily has to be one that supports life. We might be fixing a fragment that was very unlikely, statistically, to have arisen from repeated rolls of the dice. But then all the options are more or less unlikely.
Again, it is helpful to compare the situation with Darwinian evolution. If you repeatedly run a simulation of evolution on Earth, the chance of arriving at human beings is almost inconceivably remote. But if all the evolutionary paths are in flux until an act of observation fixes the exact route taken then there is no mystery. Or rather, there’s a different kind of mystery. The way in which we got here is settled: what might have happened has been fixed by observation of the very early universe. There are other mysteries, though, such as why is there life in the universe at all?
This brings me to the other sense in which the book is revolutionary. It is an appeal for us to salvage something very precious, human life, while we still can.
Saving Human Life on Earth
The final chapter of On the Origin of Time points out that our way of life is dangerously precarious and it’s our own fault. Human-made existential risks (global heating, nuclear war, AI, etc.) threaten disaster. It’s curious, given how amenable the universe is to life, that there is no evidence for extraterrestrial civilisations. Perhaps, Hertog speculates, following the thought of Italian physicist Enrico Fermi in 1950, there is a roadblock that prevents most species from being able to spread into the cosmos. We might be approaching that roadblock. Or perhaps it is that humans are dangerous and best avoided. As Hawking once put it, ‘we only have to look at ourselves to see how intelligent life might develop into something we wouldn’t want to meet.’
It’s interesting to read how a scientist contemplates the social issues involved in saving the Earth, as opposed to a socialist or anarchist thinker. Hertog believes we can still avoid the precipice and that to do so scientists and scholars will need to act together for the common good. In particular, the current path humanity is on has to change. To analyse that mistaken path, Hertog discusses a 1963 essay by Hannah Arendt, The Conquest of Space and the Stature of Man. Arendt argued that the more humanity obtains the knowledge to control the physical environment, the more we threaten our own freedom.
This is an unusual point of view in the West at least. Here we tend to believe that the scientific revolution is very positive and that the rational goals of science are bringing us towards higher truths. This is the ethos of the Enlightenment, which in turn can be seen as a significant acceleration of a way of life begun with systematic agriculture and the early class societies of about seven thousand years ago. As an aside, Marxism tends not to counterpose itself to this positive view of the scientific revolution, but usually sees itself as completing the full emancipation of humans from nature, overcoming the fetters imposed by capitalism.
It is strange to live in times when a leading practitioner of science should argue that, ‘the flight from our earthly roots that is the hallmark of modern science has also led to a chasm between our human goals and the supposedly objective workings of nature,’ but Hertog strongly agrees with Arendt. Earth alienation, the detached view, is intrinsic to much of science and is leading to world alienation. Modern science of this sort, says Hertog, ‘will ultimately prove to be a self-defeating paradigm.’
The pursuit of science and technology, stripped from all humanity is fundamentally flawed. Be it the conquest of space in the hopes of geo-engineering another planet; the search for powerful biotechnology; or the quest for a final physical theory; Hertog agrees with Arendt that these are ‘acts of rebellion against our human condition as dwellers on this planet’.
Planet Earth becomes an object like any other, something to use, and not our home. We transform ourselves from subjects of Earth to objects. We are on course to cease to be human by, ‘lowering the stature of mankind to that of a large-scale ant colony, collectivised and monitored, deprived of all freedom.’
There is a connection between Hertog’s belief in quantum holography and his opposition to the alienation of humanity from the Earth. ‘A genuine quantum outlook on the universe counters the relentless alienating forces of modern science and lets one build cosmology anew from an interior viewpoint.’
Observers have a creative role in cosmic affairs, introducing a backward-in-time element. We read the fundamentals of the history of the universe from the top down. It turns the apparent design of the universe upside down: ‘at a quantum level the universe engineers its own biofriendliness. Life and the universes are in some way a mutual fit, according to the theory, because, in a deeper sense, they come into existence together.’
Freedom. Creativity. Imagination. Participation. These are ideas usually expressed by socialists and anarchists rather than scientists addressing humanity’s relationship to the early universe. So it is encouraging and a source of hope that millions of people are reading a bestselling book about the origin of time, with its call for an about turn in practice of science. There’s a zeitgeist at play here, perhaps the owl of Minerva taking flight, because Wengrow and Graeber’s radical deconstruction of primitive communism and re-telling the story of early human societies is also a bestseller.
The skies are darkening but it is not just revolutionaries who can see this and want to find a way out while we still can.
