However, when quantum theory came along a century later, physicists realized that light ought to be made up of particles after all. Young’s interference patterns were not initially too much of a problem, since photons en masse could work in waves, just as sand can be made to ripple in a wave-like fashion. The real difficulties began when even just a single photon at a time was fired at the screen and the same interference patterns built up.
The results were totally counter-intuitive. If one slit is closed and a beam of light shone through the other then – as expected – just a single sharp line appears on the screen. If the slit is closed and the other opened, then again a single line appears in a different place on the screen. But if both slits are open at the same time, you get the interference patterns – even when just a single photon is involved. The photon seems to be interfering with itself, so to speak. As Paul Davies comments: ‘It’s almost as if the photon can be in two places at once, that is pass through both slits.’29
It gets odder. The outcome – whether light behaves as a wave or particle – depends on how the photon is detected after passing through the slits. When a light-sensitive screen such as a photographic plate is used, the interference patterns typical of a wave appear. If two telescopes or similar devices are instead trained separately on each slit, then every individual photon will be detected by only one device, showing that the particle had, as expected, passed through only one slit. But as the method of detection is chosen by the experimenter, in a sense the observer decides how he or she wants the particle to behave.
There is a more subtle but enormously significant implication. The difference between the two outcomes reflects the difference in the experimenter’s knowledge. When a light-sensitive screen is used to detect a photon, the experimenter has no way of telling which slit it has passed through, so it appears as if it has passed through both, giving a wave-like effect. With telescopes the experimenter can tell which slit the photon went through and the photon therefore obligingly acts like the particle it is supposed to be. In other words, it is not just the outcome of the experiment, but the behaviour of the particle itself that seems to depend on what the observer knows – almost as if it depends on the physicist to give it form. When he or she has specific information, the particle behaves specifically; when they have only vague information, the particle behaves vaguely, as if nobody had told it exactly what to do.
In the 1950s Richard Feynman came up with an interpretation of the double-slit experiment based on quantum mechanics that may seem bizarre – even for this strangest of disciplines – but which fits both its theory and practice. According to his interpretation a photon does not take a single path towards the target, but simultaneously takes every possible path – it really does go through both slits. The potential paths of the particle represent a series of probabilities, or possibilities, known as a ‘wave function’. It is only when the particle is observed that the wave function ‘collapses’ and the particle takes on a definite position and path. As John Archibald Wheeler, who taught Feynman, explains (his emphasis): ‘Each photon is governed by laws of probability and behaves like a cloud until it is detected … The act of measurement is the transforming act that collapses uncertainty into certainty.’30 Put another way, until it is measured the photon ‘remains an ethereal cloud of probability precisely because it is unobserved’.31
If this is correct it would apply to every particle in the universe, and to every property of every particle. They are all wave functions, waiting to receive specific values by being observed. Of course this doesn’t mean physicists have a special power that makes subatomic particles submit to their will. What the double-slit experiment and others reveal is the existence of an intimate, and positively spooky, connection between anyone’s mind and any matter in the universe.
THE MECHANISM OF GENESIS
John Archibald Wheeler (1926–2008) proposed the most far-reaching interpretation of the observer effect. One of the giants of theoretical physics, Wheeler studied under Neils Bohr and Einstein. During the 1930s he worked with Bohr and Enrico Fermi on the theory behind the atomic bomb before then moving on to work on the wartime Manhattan Project. He coined the terms ‘black hole’ (the existence of which he predicted theoretically) and ‘wormhole’. In the 1979 New York Review of Books, the mathematician Martin Gardner wrote of Wheeler:
No one knows more about modern physics than Wheeler, and few physicists have proposed more challenging speculative ideas. In recent years he has been increasingly concerned with the curious world of QM [quantum mechanics] and its many paradoxes which suggest that, on the microlevel, reality seems more like magic than like nature on the macrolevel. No one wants to revive a solipsism that says a tree doesn’t exist unless a person (or a cow?) is looking at it, but a tree is made of particles such as electrons, and when a physicist looks at an electron something extremely mystifying happens. The act of observation alters the particle’s state.32
Wheeler made a simple but profound observation about the double-split experiment that took the observer effect to a whole new level. As we have seen, the outcome – particle or wave – depends essentially on how much information the experimenter chooses to have. Wheeler argued this would even apply if the experimenter possessed the information only after the experiment had been run.
To demonstrate this he devised the simple ‘delayed choice’ thought-experiment. Imagine the double-slit experiment was set up so it had both a light-sensitive screen and, behind it, two telescopes, one trained on each slit. If the experimenter could somehow decide after the photon had passed through the slits which type of detector would come into play then, Wheeler pointed out, logically exactly the same results would apply as if the experimenter had decided what would happen in advance. The screen would show waves, the telescopes particles.
Again, the outcome would reflect the experimenter’s knowledge, but this time they would only have this knowledge after the event. So, if in the normal experiment the observer determined how the particle was going to behave, in Wheeler’s delayed choice version, they determined how it did behave. The observer could decide how a particle behaved in the past, even if only a few microseconds before. As Wheeler pointed out, thinking this process through logically, you come up with backwards causality – time working the ‘wrong’ way round.
When it was first advanced, the delayed choice experiment could only be an intellectual exercise. After all, how could the experimenter make the decision and throw the switches in the infinitesimally short time the photon was between the slit and the detector, travelling at the speed of light? But in 2006, after many unsuccessful attempts, a means of running this experiment for real was devised. A team of French physicists led by Vincent Jacques used a device that allowed a single photon to take either a single or double path, the choice being determined by a quantum Random Event Generator. In this version the experimenter had to make no choice at all, and just had to gather the information at the end of the test. Needless to say the experiment confirmed Wheeler’s predictions absolutely.33
The delayed choice experiment showed that observations determine events in the past – but how far back could it go? Wheeler came up with another sequence of arguments that showed that it could also work on a cosmic scale. At the time of writing this has yet to be tested experimentally – but the logic holds up.
A well-known phenomenon in astronomy involves the light from a distant star being bent by a body with a massive gravitational force – say a black hole – between the star and Earth. An effect of this ‘gravitational lensing’ is that, if the star is immediately behind the black hole, then from Earth we see two images of the star, one either side. Wheeler pointed out that as the light from the star consists of individual photons, this double imaging means that some have been bent round one side of the black hole, and some round the other. Effectively like being passed through the two slits in a lab. If an experimenter on Earth ran the double-split experiment using light from the star, the result should
be exactly the same as with the traditional experiment and the delayed choice version: particles or waves depending on how the experimenter chooses to detect them.
Only in this version of the experiment, the light would have been emitted from the star millions, even billions, of years ago. Obviously it would hardly be possible to decide in advance whether they should be particles or waves. So the choice of today’s observer would be to decide which side of the black hole the photons would pass, even though it happened many millions of years ago. As Wheeler explains:
Since we make our decision whether to measure the interference of the two paths or to determine which path was followed a billion or so years after the photon started its journey, we must conclude that our very act of measurement not only revealed the nature of the photon’s history on its way to us, but in some sense determined that history. The past history of the universe has no more validity than is assigned by the measurements we make – now!34
Paul Davies and John Gribbin comment on the implications of Wheeler’s argument: ‘In other words, the quantum nature of reality involves nonlocal effects that could in principle reach right across the Universe and stretch back across time.’35
From such reasoning, Wheeler came to a truly extraordinary vision of the role of the mind in the universe. Realizing that the idea that observers affect what they observe only scratches the surface, Wheeler proposed that we should think not in terms of observers but of participants. He then asked whether the difference between observation and participation might be ‘the most important clue we have to the genesis of the universe’:36
The phenomena called into being by these decisions reach backward in time in their consequences … back even to the earliest days of the universe …. Useful as it is under everyday circumstances to say that the world exists ‘out there’ independent of us, that view can no longer be upheld. There is a strange sense in which this is a ‘participatory universe’.37
In a positively Star Trek-like sound bite, Wheeler declared that: ‘We are participators in bringing into being not only the near and here but the far away and long ago.’38 From this reasoning he formulated an even more extreme version of the anthropic principle. We saw earlier that this has been conceptually divided between the weak anthropic principle (the universe looks as if it was designed for life but this is probably an illusion) and the strong anthropic principle (the universe is designed for life). But Wheeler came up with what he termed the participatory anthropic principle – that we are designing the universe. The theory’s many knee-jerk detractors were delighted to discover that its acronym is ‘PAP’.
According to Wheeler’s big idea, the universe was not designed to produce intelligent life for the fun of it; intelligent life is necessary for the universe itself to exist. Writing in 1977 he stated:
The quantum principle shows that there is a sense in which what the observer will do in the future defines what happens in the past – even in a past so remote that life did not then exist, and shows even more, that ‘observership’ is a prerequisite for any useful version of ‘reality’. One is led by these considerations to explore the working hypothesis that ‘observership is the mechanism of genesis’.39
Recognizing the momentous nature of Wheeler’s hypthothesis, Bernard Carr comments:
Wheeler has suggested a more radical interpretation in which the universe does not even come into being in a well-defined way until an observer is produced who can perceive it. In this case, the very existence of the universe depends on life.40
The theory eliminates the need for the multiverse as a solution to the dilemma of the anthropic principle. If the universe needs observers in order to exist then, ‘no universe at all could come into being unless it were guaranteed to produce life, consciousness and observership somewhere and for some little length of time in its history-to-be’.41
PAP is admittedly an extreme theory. Its potential for being misunderstood and exploited by a whole range of non-scientists including New Agers and science fiction fantasists is only too obvious. Wheeler was particularly incensed that his cosmological ideas were continually used in attempts to explain parapsychological and paranormal phenomena or were even taken to mean that they had already explained them. As a fierce opponent of psi and a board member of the American Association for the Advancement of Science, in 1969 he (unsuccessfully) opposed the admission of the Parapsychological Association as an affiliate member. Ten years later – furious at finding himself speaking alongside parapsychologists at an AAAS conference – he tried to have the decision rescinded, writing a hard-hitting paper entitled ‘Drive the Pseudos Out of the Workshop of Science’ that he and fellow sceptics circulated widely, again unsuccessfully.
At first it might seem odd that Wheeler took such a line given that his own ideas seem even weirder than the most incontinent claims of the paranormalists. However, his fury was a result of the fact that his interpretation of quantum mechanics has often been twisted to validate unexplained phenomena. Given that Wheeler seems to be saying that the minds of human observers affect the universe at a quantum level, some parapsychologists and many New Agers have taken this to mean that the minds of psychics can, for example, cause changes in the subatomic structure of a spoon, making it bend according to their will alone. Wheeler objected that this was not what he was saying at all.
Wheeler’s argument is that by discovering the laws of physics that make the universe tick, sentient observers were and are bringing them into being. But they are not actually making the laws. There is no free choice involved. In the double slit experiment, for example, the experimenter can ‘make’ the particles behave as a particle or a wave, but not as anything else. And whatever the observer is doing to influence behaviour is entirely unconscious. Such experiments show that mind and matter are intimately connected, but in a circular relationship where neither has the upper hand. It’s not a case of mind over matter, or even matter over mind – both are acting as part of the same process.
One of the intuitive difficulties with the idea of a designer universe is the notion that building a whole universe just to populate odd corners of it with intelligent beings seems rather excessive. Surely GUD could have found a more economical way to work? But Wheeler argues it makes perfect sense if we think not in terms of size but time. The universe has to be as big as it is, and to have existed for as long as it has, for the conditions required for life to have arisen. The size and age of the universe are directly related: if the universe contained only enough matter to make one galaxy, it would not be able to exist long enough to make life. (In fact, Wheeler calculated that a galaxy-sized universe would only exist for about a year.)42 Barrow and Tipler observe that certain of Teilhard de Chardin’s arguments supporting his contention that the purpose of the universe is to produce life are ‘strikingly similar to Wheeler’s idea that the Universe must be at least as large as it is in order for any intelligent life at all to exist in it.’43
Even more relevant to this present discussion, Wheeler relates his theory of the participatory universe to the work of Leibniz, one of his scientific and philosophical heroes. In so doing, Wheeler is therefore, however unknowingly, linking his theory to the Hermetic vision. In an article written in 1970, ‘Beyond the Edge of Time’, he suggests that the weak anthropic principle ‘may only be a halfway point on the road toward thinking of the universe as Leibniz did, as a world of relationships, not a world of machinery’ and asks:
Does the universe … derive its meaning from ‘participation’? Are we destined to return to the great concept of Leibniz, of ‘pre-established harmony’ … before we can make the next great advance?44
John Wheeler is by no means the only eminent physicist to accept such an apparently outrageous idea that we – and all the other intelligent species in the universe – are actually creating the universe, not only now but also back at its beginning. Stephen Hawking, along with collaborators such as American physicist James Hartle and Thomas Hertog of CERN, have embraced much t
he same idea, and for many of the same reasons. They, too, take the implications of the double-slit experiment and other paradoxes of the quantum world and apply them on a cosmic scale. The major difference with Hawking’s vision is that he embraces the multiverse, and so accepts that there are many other universes in which conditions do not support life. Quite how these universes are supposed to exist without benefit of observers is something that is left open.
In his work with Hartle, Hawking extended the idea of wave functions to the entire universe, devising a mathematical formulation – the ‘Hawking-Hartle state’, developed from one of Wheeler’s equations – to express it. Just as the experimenter in the laboratory collapses the wave function of a photon in the double-split experiment, so observations of the universe collapse its wave functions – not only now but in the past. Backward causality, in other words.
In The Grand Design Hawking argues that the traditional ‘bottom-up’ approach to the history of the universe is wrong. Instead of starting with the big bang and working forwards, extrapolating the laws of physics to work out why the universe now is the way it is, we should take a ‘top-down’ line, working backward from the present. This would allow for the fact that, building on the work of Feynman and Wheeler, our existence now determines how the universe began and evolved: ‘We create history by our observation, rather than history creating us.’45 Or as New Scientist put it in a report on Hawking and Hertog’s recent work: ‘A measurement made in the present is deciding what happened 13.7 billion years ago; by looking out at the universe, we assign ourselves a particular, concrete history.’46
Although the comparison would no doubt have truly appalled Wheeler and probably wouldn’t find favour with Hawking, such ideas chime very well with the global coherence effect found by Dick Bierman and the Global Consciousness Project. This shares with the participatory universe hypothesis the basic idea that mind is intimately bound up with matter – indeed, that the mind is even a property of matter. Both show that the very presence of thinking entities affects the physical universe at a quantum level.
The Forbidden Universe: The Origins of Science and the Search for the Mind of God Page 31