If the Universe was built and the builder wanted to leave a message, where would they have left it? In the ‘afterglow’ of the Big Bang
Since the inflationary theory implies that the entire observed universe can
evolve from a tiny speck, it is hard to stop oneself from asking whether a
universe can in principle be created in the laboratory.
Alan Guth, The Inflationary Universe, 1997
Teacher told my parent that I am the slowest youngster in my class, but today
I made a star in the third quadrant of kindergarten.
James E. Gunn, ‘Kindergarten’,1970
Today is the day. For two years the satellite has been drifting out in the darkness 1.5 million kilometres beyond the Earth. For two years it has been quietly measuring the cosmic background radiation, the cooled ‘afterglow’ of the Big Bang fireball which permeates every pore of space. Now the last gigabyte of data has been processed and the scientists who have devoted years of their lives to the mission crowd around a computer monitor at Mission Control.
In the expectant hush, fluorescent digits begin to scroll down the screen. To everyone’s astonishment, there is a pattern. An unmistakable pattern. Someone has spotted numbers they recognise – the ‘coupling constants’ of the standard model of particle physics. One scientist whistles through her teeth, another gasps. This is no random signal from the beginning of time. It is a message from the Creator. And what it is saying is: ‘This is how up I built the Universe.’
Surely such a scenario is pure science fiction? Not necessarily, according to two physicists in the US. Stephen Hsu of the University of Oregon in Eugene and Anthony Zee of the University of California at Santa Barbara asked themselves the question: if the Universe was built, and the builder wanted to leave a message for all the Universe’s inhabitants, where would be the best place to leave it? ‘In our opinion, there is only one place,’ says Hsu.
When Hsu and Zee talk about the Universe being ‘built’, it needs to be stressed they are talking about ‘someone’ or ‘something’ creating the initial conditions that set the Universe in motion 13.7 billion years ago. They are not in any way subscribing to the ‘intelligent design’ claim that a Supreme Being individually designed the creatures that live on Earth. Furthermore, the someone or something that lit the touch paper of the Big Bang need not be a Supreme Being – God – but simply a superior being – a creature that is basically like us, only far more technologically advanced.
One reason for thinking that the Universe could have been made by a superior being or superior beings is that, remarkably, we already know the recipe for making a Universe. It is called ‘inflation’.
Inflation, a brief period of super-fast expansion, is widely believed to have occurred in the first split-second of the Universe’s existence. As pointed out before, inflation was driven by the vacuum, which in the view of modern physics is not empty at all but seething with restless energy. According to proponents of inflation, the vacuum at the beginning of time was in a peculiar state quite unlike today’s vacuum. In fact, it was so peculiar that it possessed repulsive gravity rather than the familiar attractive variety. This caused the vacuum in only a brief interval of time to balloon in volume by a staggeringly large factor. When inflation finally spluttered to a halt, the enormous energy contained in the, by now vastly inflated, vacuum had to go somewhere. And it went into making matter and heat – in short, it created the ferocious fireball of the Big Bang.
Remarkably, inflation could have been triggered by only a tiny ‘seed’ of matter – perhaps as little as a kilogram. This astonishing realisation has led to the much-repeated declaration by cosmologists that the Universe, with its countless galaxies and stars, is the ‘ultimate free lunch’. Apart from the measly initial seed, all cosmic matter was born when the energy of the vacuum was dumped abruptly into mass-energy of subatomic particles.
The recipe for creating a universe is therefore clear: take a small seed of matter and subject it to the conditions that once triggered inflation in our Universe. Of course, there is a hitch – if there wasn’t, someone would already have made a universe in the laboratory! The hitch is that, in order to create the peculiar state of the vacuum that leads to inflation, the seed must be squeezed to a tremendous density – equivalent to 1094 grams of matter crammed in a volume the size of a sugar cube.
Achieving such an ultra-compressed state of matter is clearly way, way beyond our technological capabilities. So, although we can see in principle how to make a universe in a laboratory, in practice we have no hope of doing so. Nevertheless, such an extraordinary feat may not be beyond the capabilities of a super-advanced civilisation. And this is the point. If a super-advanced civilisation could build a universe, then it stands to reason that such a civilisation could have built our Universe.
Why anyone would want to build a universe is a difficult question to answer. Guessing the motivations of super-advanced beings is a bit like a bacterium trying to guess the motivations of a human being. However, one possibility is that they would want to do it for exactly the same reason that we often do scientific experiments – simply to see what happens.
The cosmologist Edward Harrison has pointed out that, if the Universe was indeed created by superior beings, it could explain two puzzling features of our Universe. The first is why the laws of physics appear to be ‘fine-tuned’ for the existence of stars and planets and, ultimately, intelligent life like us. None of these things would be possible if, for instance, the forces of nature such as gravity were even a few per cent weaker or stronger than they actually are. Why, then, are the laws of physics just right for us to be here? Easy, says Harrison. If our Universe was made by superior beings, it would either be deliberately designed for life or else it may have inherited the conditions of its builders, who by definition, lived in a universe compatible with life.
A second very puzzling feature of our Universe was pointed out by Einstein and has never been satisfactorily explained. ‘The most incomprehensible thing about the Universe,’ he said, ‘is that it is comprehensible.’ Why, for instance, do we not live in a universe whose laws are so bafflingly opaque that we could never figure them out? Harrison has an answer. If our Universe was built by superior beings rather than an incomprehensible Superior Being, he says, it was created by comprehensible beings – beings far in advance of us but basically like ourselves. Intelligent but also intelligible. They made our Universe to be like theirs, and their universe was, in turn, understandable. How could it not be? They had to have enough understanding of it to manipulate it and make our Universe.*
Hsu and Zee have no more evidence than Harrison that the Universe was made by a superior intelligence. However, this is not a concern to them. They are merely pointing out that, if the Universe was built, the builder may have wanted to leave a message to the Universe’s inhabitants, saying perhaps: ‘This is how I did it.’ ‘The question is: where would they leave such a message?’ says Hsu.
Scientists and science-fiction writers have long speculated about where on our planet a message could be left in the safe knowledge that it would survive for a long time. Say, for instance, extraterrestrials came to the Solar System millions of years ago and wanted to leave a calling card for any intelligent creatures that might one day evolve on the promising third planet from the Sun. One possibility would be to inscribe a notice in an outcrop of solid rock somewhere on Earth. However, such a message would inevitably be worn away by the action of weather. A far better place to leave a message, argued science-fiction writer Charles Sheffield, is the genome of living things. Although natural selection causes DNA to continually change, or ‘mutate’, there are regions of DNA – junk DNA, or ‘introns’ – which stubbornly retain their identity from generation to generation. Such regions, Sheffield concluded, would be an ideal place for ET to leave a message for us. Just imagine. At this very moment the long-sought communication from the stars could be written in the heart of every fat red blood cell coursing through your veins!
DNA, however, is very specific to the Earth. It is not a viable message medium for a Creator who wished to advertise his handiwork to all inhabitants of the Universe. Nor is an artefact buried on the Moon like the mysterious ‘monolith’ excavated from Tycho crater in Arthur C. Clarke’s 2001: A Space Odyssey.
Other scientists, including the planetary scientist Carl Sagan, have suggested that a message from a super-advanced intelligence might be buried in the digits of a fundamental cosmic number such as pi, the ratio of the circumference to the diameter of a circle. To date many millions of digits have been computed, with not the slightest sign of any pattern in those digits. However, Sagan, in his science-fiction novel Contact, speculated that, after a billion digits, or a trillion, a pattern will eventually be found to emerge – and this will be a message from the Creator of our Universe.
Hsu and Zee accept that Sagan’s idea is plausible. Unlike Sagan, however, they ask themselves where in the ‘physical’, rather than the abstract mathematical, Universe might a message be left – a message that could be seen from every star in every galaxy in the Universe? ‘The answer is clear,’ says Hsu. ‘The cosmic background radiation.’
Ninety-nine per cent of all the Universe’s photons are not in the light of stars and galaxies. They are instead tied up in the cosmic background radiation.* If we had eyes that were sensitive to short-wavelength radio waves rather than visible light, this would be glaringly obvious to us. We would see all of space glowing like the inside of a light bulb. ‘And what we can see on Earth everyone else in the Universe can also see,’ says Hsu.
The cosmic background radiation is the relic heat of the Big Bang fireball. It has been cooled so greatly by the expansion of the Universe in the 13.7 billion years since the beginning of time that today it has an average temperature of only about -270 degrees Celsius. The reason it is still all around us today is simple – it was bottled up in the Universe and had absolutely nowhere else to go. Tune your TV between the stations and about 1 per cent of the ‘static’ on your screen will be the microwave relic of the Big Bang. Before it struck your TV aerial, the last time it interacted with matter was in the blistering inferno at the beginning of the Universe.
As noted earlier, microwaves arriving at Earth from very different directions come from regions in the Big Bang fireball that were not in ‘causal contact’ at the time the cosmic background radiation originated. This means the emitting regions were so far apart that light – the fastest thing in the Universe – could not have travelled between them. The importance of this for Hsu and Zee is that it means that nothing or nobody could have tampered with the cosmic background radiation in its entirety even at this early epoch – about 450,000 years after the Universe’s birth. The only time a message could have been impressed on the fireball radiation was at the very beginning of the Universe – in its first split-second of existence.
In other words, only someone or something at the beginning – the builder of the Universe – could have left a message in the cosmic background radiation. And, after they had left it, no conceivable process could have erased it.
But how exactly would the builder of the Universe encode a message in the cosmic background radiation? Hsu and Zee have a very specific idea. It requires a little diversion into the technicalities of the cosmic background radiation.
The average temperature of the cosmic background is 2.726 degrees Kelvin. But, as pointed out before, there are subtle variations in its temperature from place to place in the sky – ‘hot spots’, which are ever-so-slightly warmer than average, and ‘cold spots’, which are ever-so-slightly cooler than average. These arise because the matter in the Big Bang was ever so slightly lumpy. The lumps have since been magnified by the remorseless action of gravity to make the galaxies including our own Milky Way.
The hot spots and cold spots in the cosmic background radiation occur at all sizes. For instance, there are big blotches which stretch across much of the sky and, superimposed on these, smaller goose pimples. To make sense of everything, astronomers like to separate out the different components, breaking up their ‘temperature map’ of the microwave sky into what they call ‘multipoles’.
The simplest multipole is the ‘dipole’. This is simply one huge hot spot and one huge cold spot. Actually, this has nothing whatsoever to do with the Big Bang. Rather, it is the temperature variation caused by the motion of the Milky Way which is flying at hundreds of kilometres a second through the photons of the cosmic background radiation. This makes the afterglow of the Big Bang appear hotter in the direction the Milky Way is flying and colder in the opposite direction.
After the dipole temperature variation, the second simplest multipole is the ‘quadrupole’. The best way to think of this is as two dipoles – that is, two hot regions and two cold regions. Next comes the third simplest multipole, the ‘octupole’, which consists of three dipoles – that is, three hot regions and three cold regions. You get the idea. The simplest multipole components correspond to the biggest blotches and the more complicated multipoles to the smallest freckles.
Now, associated with each multipole is a maximum temperature variation – the difference between the coldest and hottest region. Astronomers call it the ‘amplitude’. For instance, the amplitude of the dipole variation in temperature is several hundred times bigger than that of the quadrupole. ‘It is these amplitudes that we believe are the ideal places for the Creator of the Universe to lodge a message to the Universe’s occupants,’ says Hsu.
Hsu and Zee point out that, within the foreseeable future, scientists will measure not only the amplitude of the dipole, quadrupole and octupole variations in the cosmic background radiation but the amplitude of the first 10,000 multipoles. This will provide them with 10,000 unique numbers describing the cosmic background radiation. Exactly how much information can be extracted from these 10,000 numbers depends on how accurately it is possible to measure them. Hsu and Zee estimate that ten bits of information could be encoded in each amplitude, making a grand total of 100,000 bits. Not a lot compared to the gigabits that can be stored on a PC’s hard drive but enough to leave a potentially priceless message for the Universe’s occupants.
How exactly would the builder of the Universe fix those amplitudes? Well, the lumpiness of matter is thought to have itself originated in the first split-second of the Universe when the vacuum on the microscopic scale was seething like the surface of water boiling in a saucepan. Hsu and Zee speculate that anyone who was able to manipulate these undulations of space could imprint indelible marks on the cosmic background radiation.*
What might the Creator put in the 100,000 bits available to it? That is of course a difficult question. However, Hsu and Zee speculate that they might tell us how the Universe has been built. As far as we are aware, four ‘fundamental’ forces orchestrate everything that happens in the cosmos. As discussed before, these forces arise from even more fundamental entities called gauge fields. The gauge fields, in turn, can be described by ‘matrices’ – nothing more than tables of numbers.* It is these numbers that Hsu and Zee think the Creator might encode in the cosmic background to tell us how creation is put together. ‘In effect, they would be saying “Hey guys, the Universe is governed by gauge fields, with the following structure …”’says Hsu.†
Some physicists believe, however, that the most fundamental theory describing reality is ‘string theory’, which views the fundamental entities – the building blocks of all matter – as ultra-tiny ‘strings’, vibrating in ten-dimensional space. If string theory is the correct description of our Universe, then the Creator might have left the details of string theory in the cosmic background. ‘Of course, these are just specific suggestions,’ says Hsu. ‘Perhaps our collective scientific mind is still too puny to guess what the message on the billboard in the sky might read.’
Maybe the Creator simply signed their creation with the equivalent of ‘I woz ’ere’!
Hsu and Zee urge that, when more accurate cosmic background data becomes available, it should be analysed carefully for possible patterns impressed on it by the builder of the Universe. ‘We believe we have raised an intriguing possibility,’ says Hsu. ‘Searching for a signal in the cosmic background radiation may be even more fun than the search for extraterrestrial intelligence.’
* See my book, The Universe Next Door (Headline, 2002).
* See my book, Afterglow of Creation (University Science Books, Sausalito, California, 1996).
* Specifically, Hsu and Zee propose a mechanism in which the self-interactions of the ‘inflaton’ – the field responsible for inflation – caused the variations in lumpiness. This proposal relies on physics – quantum field theory – that physicists consider well understood. It requires only that the superior being fine-tuned the inflation dynamics.
* See Chapter 7, ‘Patterns in the Void’.
† Of course, Stephen Wolfram believes that it may be impossible for us to recognise any message from a superior intelligence! See Chapter 9, ‘An Alien at My Table’.
‡ See Chapter 3, ‘Yoga Universe’.