Theatre of the Invisible

I gave this talk yesterday at the meeting Performing Science: Dialogues Across Cultures at the University of Lincoln. It seemed brief enough to put up here. _____________________________________________________

The actor David Garrick had a set-piece during his performances of Hamlet, the role for which he was most famous, that electrified London theatre audiences in the eighteenth century. It came when the ghost enters at the start of the play. According to the St. James Chronicle in 1772, “As no Writer in any Age penned a Ghost like Shakespeare, so, in our Time, no Actor ever saw a Ghost like Garrick.” The German scientist Georg Christoph Lichtenberg wrote that “His whole demeanour is so expressive of terror that it made my flesh creep even before he began to speak.”

Garrick is shown in the midst of this tour-de-force in a contemporaneous print (Figure 1). Doesn’t it seem here as if his hair is actually rising from his scalp? And in fact, it really is. But not even Garrick could raise his hair at will. He achieved the spine-tingling effect (which goes by the splendid name of horripilation) with the aid of a London wig-maker named Perkins, who created a mechanical wig powered by hydraulics.



Figure 1 David Garrick as Hamlet, on seeing his father’s ghost in Act I. Mezzotint after a painting by Benjamin Wilson, 1756.

This wasn’t just a cheap trick. Garrick’s approach to what was then seen as naturalistic performance was informed by a Cartesian view of human physiology, in which the body was regarded as a kind of hydraulic mechanism driven by fluids called animal spirits that were pumped around the organs and limbs. Within this view, an artificial hydraulic wig was little different from the way real horripilation was thought to work by a rush of fluids to the head. Like all emotion, it was simply a matter of biomechanics.

But there is another defence of Garrick’s potentially absurd ‘fright wig’: he needed all the help he could get, because he’d set himself the task of conjuring the illusion of the ghost by gesture alone. Whereas previously the dead king was generally played by an actor, Garrick insisted that he should be invisible: a disembodied voice whose presence was seen only by the actors. But theatrical invisibility is a difficult trick – as film makers later discovered, it needs visible signifiers to sustain the illusion.

Garrick’s choice represented a decision not just about staging but about what the ghost in Hamlet – on which the plot of course turns – truly means. It is a statement about how the entire play should be interpreted. Because we’re then forced to ask: is this a real spirit, or just a figment of Hamlet’s tortured mind?

Partly this is a question about the significance of ghosts in Shakespeare’s time. But I want to locate this issue of the visibility of his ghosts within a wider debate about appearance, illusion and spectacle in theatre. Because it is my contention that, from the eighteenth to the early twentieth centuries in particular, science – and particularly optical science – became strongly linked to theatre, stage magic and the advent of cinema, in ways that were as much thematic as they were instrumental.

Ghosts were a common, even clichéd sight on the Elizabethan stage. They served as narrators, popping up to fill in a bit of back-story. As such, they were no cause for alarm in either implication or appearance, being represented by a sort of Jack-in-the-box puppet, or else by an actor with whitened face, dressed in clothes made of furry leather. They were a device borrowed from the plays of Seneca, which supplied a model for the revival of tragedy during the Renaissance. The Senecan ghost typically appeared in the prologue, calling for an act of revenge that motivated the play’s tragic plot.

But the ghost in Hamlet is no glove puppet. He’s made to sound hardly less terrible to the audience than he is to Hamlet and his friends: the sight “harrows me with fear and wonder”, gasps Horatio. That’s what Shakespeare did to the theatrical ghost: he made it real, humanized, haunting and disquieting. His spirits are really spooky, and in some ways they represent a supernatural stage presence that has never been equalled.

The Senecan ghost is merely a “bit of dramatic machinery”. But ghosts in Shakespeare, and in some of the Jacobean plays that came after, leave the audience guessing. Indeed, they leave the characters guessing: what sort of apparition is this? This is a question about what ghosts meant in the popular superstition of the time. The answer wasn’t simple, but we can at least say that it was determined largely by your religion. Catholics believed that the souls of the dead reside for a time in Purgatory before being admitted (if they warrant it) to heaven. This gave souls a period in which to haunt the living. But Protestants rejected the idea of Purgatory – which makes it puzzling how a dead soul can feature in what is undoubtedly a Protestant play. Might, then, the ghost be a demon masquerading as the king, to provoke Hamlet into acts of slaughter and, indirectly, Ophelia into sinful suicide?

This was the choice, it seems: ghosts were either dead souls, or they were demons – or maybe angels. All were real entities; as the Shakespeare scholar Robert Hunter West has said, when these plays were first performed “Englishmen were seriously aware in a way that we are not of an invisible world about them.” Around this time there was a vigorous debate about the meaning and status of ghosts, and several learned books were published that attempted to provide them with a taxonomy.

One of the most influential was by the theologian Noel Taillepied, called A Treatise of Ghosts. Taillepied claimed that the souls of the departed may be returned to earth by God to deliver a message. Shakespearian ghosts indeed do always have motives and messages to impart, and sometimes only the intended recipients can see them, or at least hear them. The notion of a ghost who, like Banquo in Macbeth, haunts the guilty party alone was well established in folk tradition. If we are inclined to attribute this now to the fevered imaginings of a guilty conscience, we shouldn’t imagine that Shakespeare was in contrast blindly literal – the powers of invocation and agency attributed to the imagination in the late Renaissance leave no clear distinction between a ghost being a projection of the mind and an objective phenomenon.

Ghosts didn’t, as one might expect, go out of fashion with the alleged rationalism of the Enlightenment. Certainly in popular superstition they remained as present as ever, as the famous Cock Lane Ghost of London in the mid-eighteenth century attested. That case ended in a prosecution for fraud, after investigation by a committee that included Samuel Johnson. But Johnson himself remained a firm believer in ghosts, even if not in this particular one.

What changes in our perceptions of the spirit world is not the question of whether it exists but of what it means. In the nineteenth century, the rise of spiritualism saw ghosts become sources not so much of terror as of consolation: mediums offered the opportunity to speak with the souls of the departed loved ones. And what is most striking in this period, certainly for the purposes of this meeting, is how ideas about invisible beings and unseen spirit worlds co-evolve with the development of science and technology, and also with the traditions of the theatre.

For one thing, spiritualist séances were undoubtedly pieces of theatre in themselves, designed to astonish and confound their audiences and prepared with a great deal of stagecraft (Figure 2). Here is an account by William Crookes, one of the many scientists who tried to subject spiritualism to scientific investigation, of a séance conducted in 1871 by the famous medium Douglas Home:

"At first we had rough manifestations, chairs knocked about, the table floated 6 inches from the ground and then dashed down, loud and unpleasant noises bawling in our ears and altogether phenomena of a low class. After a time it was suggested that we should sing, and as the only thing known to all the company, we struck up ‘For he’s a jolly good fellow’. The chairs, tables and things on it kept up a sort of anvil accompaniment to this. After that D. D. Home gave us a solo – rather a sacred piece – and almost before a dozen words were uttered Mr Herne was carried right up, floated across the table and dropped with a crash of pictures and ornaments at the other end of the room. My brother Walter, who was holding one hand, stuck to him as long as he could, but he says Herne was dragged out of his hand as he went across the table."

The group was subsequently treated to accordions playing themselves, floating lights, books dashed about and disembodied hands stroking their faces. The effect must surely have been overwhelming – both exciting and frightening, and doubtless calculated to inhibit objective assessment.



Figure 2 Victorian séances involved many strange goings-on that relied on carefully prepared and executed illusionistic trickery.

And as Crookes’ case shows, many scientists were taken in by all this – not simply because they were credulous, but because they surely wanted to believe. And also because some of them felt that they had more reason than ever to do so. The invention of the telegraph in the 1830s and 40s showed that it was possible to send messages instantly over immense distances, even spanning the Atlantic once the cables had been laid in the 1860s. With the appearance of the telephone a decade later, it became possible to hear voices directly over such a distance. And in the 1890s, the development of radio broadcasting by Marconi and Oliver Lodge meant that these signals didn’t even need a wire to convey them – they could be sent through the invisible ether. Many scientists figured that, if it was possible to hear the voice of someone who wasn’t physically present, it was not so hard to imagine that one might also hear the voices of those who were not even alive. Spiritualism was even sometimes called celestial telegraphy, and wireless broadcasting led people to suspect that the ether was a vast, invisible sea filled with all manner of voices, coming from who knew where. Rudyard Kipling made this analogy in his 1902 short story “Wireless”, in which some early radio hams pick up random messages from ships offshore while in the same building a man feverish from consumption acts as a human receiver for snatches of poetry by Keats that he picks up from some unknown and perhaps long dead source.

These speculations got another boost from the discovery of X-rays in 1895 (Figure 3) – an invisible form of radiation like light, but of a shorter wavelength. Perhaps thoughts might be transferred from person to person, or from the dead to the living, by similar invisible rays sent through the ether?



Figure 3 The X-ray image taken by Wilhelm Röntgen of his wife’s hand, c.1895.

And as this image shows, the technology of photography, devised in the 1830s, could make these invisible rays visible – this is the rather spooky image taken by the discoverer of X-rays, Wilhelm Rontgen, of his wife’s hand, and when she saw it she is said to have exclaimed “I have seen my death!” From its earliest days, photography seemed to be as much about revealing the invisible as documenting the visible. Because the surface of glass plates used to hold the emulsion could preserve faint images of an earlier exposure, some early photographers found that ghostly figures sometimes appeared in their images when the plates were reused. It was soon decided that these were spirits, and ghost photography because a lucrative business in the late nineteenth century. One of the first entrepreneurs of this business was an American named William Mumler, who set up a ‘spirit photography’ business in Boston and New York (Figure 4).



Figure 4 Abraham Lincoln’s shade consoling his widow, in a “spirit photograph” taken by William Mumler. The Lincolns were enthusiasts of Spiritualism, and were said to have conducted séances in the White House.

Even when scientists explained how such double exposures were easy to fake, it did little to diminish the popularity of the genre, for in its mysterious ability to capture the instant and to solidify intangible light photography seemed virtually a supernatural medium itself. Didn’t it, after all, convey a weird kind of immortality – and paradoxically, by doing so, remind the sitter that death awaits us all?

It’s quite natural that one of the first uses of photography would be to make invisible beings visible. For optical technology has always been closely allied with magic, and also with the theatre. It was long thought capable of revealing what went otherwise unseen, particularly spirits, souls and demons. The camera obscura, the forerunner of the photographic camera, in which natural scenes are projected through a small opening into a darkened space (Figure 5), was known since at least the eleventh century, and was popularized in the sixteenth century manual of natural magic by the Italian Giambattista della Porta (who was also a popular dramatist). By the early seventeenth century mountebanks were using such devices to astonish audiences.



Figure 5 The camera obscura, as depicted in Athanasius Kircher’s Great Art of Light and Shadow (1646).

Looking-glasses that produce figures “at a distance in the air” also featured in the magic lantern, an early form of projector that became a stalwart device of optical natural magic. It was described by the Jesuit inventor and mystical philosopher Athanasius Kircher in 1646: light is passed through an image painted onto glass and then through a lens before falling onto a screen (Figure 6). By the time Kircher was writing, magic lanterns were becoming commercialized. The Danish mathematician Thomas Walgensten traveled across Europe selling these lanterns and using them purportedly to summon ghosts.



Figure 6 The magic lantern, as shown by Kircher.

The magical stage spectacles of the late eighteenth century straddled this ambiguous boundary. The German illusionist Johann Georg Schröpfer held séances in his Leipzig coffee shop in which he used the magic lantern, projected onto smoke, to summon ghosts. Schröpfer’s performances were perhaps the first ‘entertainment séances’, and his techniques were copied by the German Paul Philidor, whose popular public displays in the early 1790s were unashamedly eye-catching and became known as “phantasmagoria” (Figure 7). Subsequently, Étienne Gaspard Robertson used magic-lantern back-projection in his “Fantascope” shows, in which, by mounting the device on wheels, he could make the projection grow rapidly larger or smaller so that ghouls and demons might seem to rush upon the terrified audience.



Figure 7 An advertising bill for the Phantasmagoria show of Paul Philidor in 1801.

Robertson explicit sought to scare his public with visions of ghosts and devils (Figure 8): he was in effect producing the first horror films. He was in fact a professor of physics with a special interest in optics, who realised the commercial potential of optical trickery when he attended one of Philidor’s extravaganzas. And although he made no pretence of possessing magical abilities, he exploited his specialist knowledge while artfully keeping his audiences guessing about what they were seeing.



Figure 8 The light show of Étienne Gaspard Robertson amazes and terrifies an audience in the early nineteenth century.

The most famous illusionistic ghost of the stage also comes from this collusion of science demonstration and pure theatre. In the mid-nineteenth century, the Royal Polytechnic Institute in London put on magic and séance shows to show how paranormal activities could be faked. One of the lecturers was the chemist and science popularizer John Henry Pepper, who later set up his own “Theatre of Popular Science and Entertainment” at the Egyptian Hall in London. Pepper collaborated with the engineer Henry Dircks in the late 1850s to create a technique for projecting the reflection of a hidden actor onto a huge, slanted sheet of glass: a semi-transparent apparition perfect for depicting ghosts (Figure 9). Plays featuring ‘Pepper’s ghost’, including Hamlet, Macbeth and A Christmas Carol, became sensations throughout Europe and the US.



Figure 9 Pepper’s ghost.

The Egyptian Hall was the centre of theatrical magic and scientific illusion in the nineteenth century. Perhaps the most famous residency was that of John Nevil Maskelyne, a watchmaker who began the foremost dynasty of British stage magicians (and who was, incidentally, the inventor of the pay toilet) (Figure 10). In 1905 Maskelyne and a group of other British magicians founded the Magic Circle, dedicated to the art of stage magic and illusion. Like many of these stage magicians, Maskelyne was also a debunker of spiritualists and mystics claiming special powers.



Figure 10 A playbill for the illusion and magic show of John Nevil Maskelyne in the late nineteenth century.

This role of illusionism is clear from Albert Allis Hopkins’ now classic 1898 manual of magic, in which the American amateur magician Henry Ridgely Evans proclaimed that “Science has laughed away sorcery, witchcraft, and necromancy.” Hopkins shows how stage magicians of the Victorian era made avid use of the newest scientific discoveries. He said that X-rays, discovered only two years before the book was published, “are now competing with the most noted mediums in the domain of the marvellous.” Hopkins describes a trick in which a man dining alone is suddenly cast into darkness, whereupon he vanishes and the audience sees, seated across the table, a glowing skeleton, lit up by a hidden X-ray generator (Figure 11).



Figure 11 A glowing, macabre dinner guest is conjured up using X-rays (from the generator on the right) to stimulate luminescence from a skeleton painted in a phosphorescent material, as depicted in Albert Hopkins’ 1898 book of stage magic.

The elaborate illusionism of the theatrical light-show found a new home in the early days of cinematography. In the late 1880s Thomas Edison began to create a kind of electrical magic lantern called the Kinetoscope that projected a series of still images in rapid succession to create the illusion of movement. In 1894 he opened a Kinetoscope parlour in New York, where for a few cents one could watch the first motion pictures, each lasting a minute or so. Meanwhile, the Lumière brothers turned the magic lantern into a portable, manually operated movie projector called the Cinématographe that threw the image onto a screen. A Parisian audience watched the first public screening in 1895.

In the audience for that premiere was the Frenchman George Méliès, who had developed his own form of illusionistic magic at the Paris theatre he owned. He promptly bought a movie camera and started making films himself. Many of these used his existing stage tricks, supplemented by the new illusionistic possibilities that cinematography offered. He made 78 films in 1896 alone, and over 500 during the next two decades. Several of them were ghost films, sometimes aimed more at slapstick than chills (Figure 12).



Figure 12 A scene from George Méliès’ comedy The Apparition, or Mr Jones’ Experience with a Ghost (1903).

Given this genealogy of cinema, it is no surprise that marvels soon took over. Films of ghostly and supernatural phenomena weren’t simply an early genre of cinema – they were its natural subject, for the motion picture should properly be seen not so much as “celluloid theatre” but as celluloid magic. Jacques Derrida seemed to discern this when in 1982 he called cinema “the art of ghosts, a battle of phantoms.”

What ought we to conclude from all of this?

First, that the first marriage of science and theatre happened in the arena of the magical and the illusory, and in particular in the disputed area where science and folk belief have vied for authority over the invisible.

Second, that science and technology have long had a performative aspect that was particularly prominent in the late eighteenth and the nineteenth centuries, and which involved a delicate interplay between explanation, mystification and spectacle, of the kind that I sense still persists in the Royal Institution Christmas Lectures.

Third, cinema should perhaps be a stronger part of this discourse, in the sense that its relationship to theatre, particularly in terms of its genesis, becomes much clearer once we acknowledge the close associations with optical technologies and illusionism.

And finally, I think, we should be reminded here of the role of imagination, which, both in science and in theatre, is needed to span the gulf of what isn’t known or cannot be expressed. Imagination is rarely spoken of today in science, but in a famous 1870 essay “Scientific Use of the Imagination”, John Tyndall argued that via the imagination “we can lighten the darkness which surrounds the world of our senses.” It is in its capacity to permit and depict imaginative leaps that theatre can help to illuminate and perhaps even extend some of the meanings of science.

Is music just about sex?

This piece (after editing) has just gone live on BBC Future. I don’t want to knock this PRSB paper, which reports intriguing findings. But please, journalists, a bit of proportion, even (especially?) with this steamy subject matter. For one thing, what exactly is it you will be imagining if I were to say to you “I’m going to play you a piece of music, and I want to imagine you having sex with the composer…”?

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Humans have made music for more than 40,000 years – the age of the earliest known instruments, flutes made from hollow animal bones. But no one knows why. Of all the theories that have been proposed, one of the most enduring and alluring comes from Charles Darwin, who suggested that it’s all about sex. “Musical notes and rhythm”, he wrote in The Descent of Man (1871), “were first acquired by the male and female progenitors of mankind for the sake of charming the opposite sex.”

Darwin’s idea was motivated partly by analogy with bird song, which does indeed often function to attract mates. But not only is there still debate about whether bird song qualifies as “music” in the same sense as human song, but there has been little reason to suppose that humans too use music primarily for courtship.

Now psychologist Benjamin Charlton of the University of Sussex in Brighton, England, offers some evidence to support this sexual-selection hypothesis. He has found that women’s sexual preferences for composers changes during their menstrual cycle, and that they prefer composers of more complex music – who might be construed as more capable mates – at the most fertile point of the cycle [1].

OK, don’t all shout at once – yes, there is a lot to argue over here. But let’s start at the beginning: what’s so special about music?

In answering that question, two things stand out. First, there are no cultures known that lack music – even if they lack a written language. It is as close to a universal human trait as you could hope for. Second, music – unlike, say, cooking, farming, talking, raising a family – doesn’t obviously have any benefit. Of course, it does have a benefit: we love it, it makes us joyful or transports us into tears, rapture and dance. But there’s no obvious, tangible result of music that we can definitely link to any evolutionary advantage.

It’s no wonder, then, that the question of the origins of music has excited such passionate debate. There is evidently something here that is crucial to human existence – we seemingly can’t do without music – but it’s awfully hard to say why, not least because music began way before recorded history. There is no shortage of ideas [2]. Some think that music began as a way of fostering social cohesion, a ‘tribal’ role that still persists today. Others say that it began in the sing-song of mother-to-infant communication, an exaggeration of tones called “motherese” that people all over the world practice. Others think that music and language were once merged into a composite form of communication dubbed “musilanguage”, from which music split as a vehicle of the emotions while language became all about semantic meaning.

But Darwin’s notion of music as an agent of sexual selection remains a favourite, not least because it has his name attached. Darwin regarded sexual selection as an adjunct of natural selection: it was “survival of the sexiest”, regardless of whether the sexual attributes had any other survival benefits. In this view, skill at singing and making music functioned like the peacock’s tail: useless, even an impediment, but attention-catching.

But it’s conceivable that such sexual displays do offer honest clues about the bearer’s “good genes”. The male peacock might be saying “I’m so ripped that I can survive even when encumbered with this absurd thing.” Likewise, a musician able to make complex and beautiful music might be displaying his or her (but usually his) superior skills of cognition, dexterity, stamina and all-round fabulousness. Falling for a musician then makes good evolutionary sense.

The link between sex and music might seem indisputable. Rock musicians have gaggles of sexually available fans at the height of their fertility, and no one made the guitar more explicitly phallic than Jimi Hendrix. (This is no modern phenomenon – Franz Liszt’s recitals set women swooning too.) There’s some anecdotal reason to think that music production declines after sex – Miles Davis attested that musicians are often celibate before big concerts, to retain their ‘edge’. And in case you’re thinking that being a musician didn’t do much for the survival prospects of Hendrix, Jim Morrison or Kurt Cobain, bear in mind that – as Darwin himself pointed out – some male birds drop dead from exhaustion when singing in the breeding season. It’s worth the risk for the sake of becoming a sexual beacon (and after all, Hendrix did father three children).



A sexual-selection origin of music might also help to explain the apparent impulse towards diversity, creativity and novelty, for many male songbirds also develop large repertoires and variety in an effort to produce the most alluring mating signal. And doesn’t the excess of the peacock’s tail – the result of a well-attested runaway tendency in selection of sexual characteristics – seem to speak to the towering stacks of amplifiers and speakers, the pyrotechnics, the outrageous costumes? In short, mightn’t it explain the phenomenon that is Kiss?



But this is part of the problem with Darwin’s idea: it is just too alluring, inviting “evidence by anecdote”. These aren’t much more than Just So stories, and culturally specific ones at that. Songs in pre-literate cultures are by no means the tribal equivalents of ‘Let’s Spend the Night Together’: those of the Australian Aborigines, for example, express the singer’s feelings as a member of the community. Most Western music in the Middle Ages was practised by (supposedly) celibate monks. And in some African societies, musicians are regarded as lazy and unreliable, and so poor marriage material. (Hmm… Pete Doherty, anyone?)

Besides, hard scientific evidence for sexual selection in music is been scant and equivocal. For example, one study in 2000 reported that, in classical concerts, there were significantly more women in the seats nearer the (predominantly male) orchestras than in the back rows – a genteel form, it was suggested, of the female hysteria that greeted the Beatles in concert [3].

If women do pick sexual partners on the basis of creative or artistic traits, one would expect changes in their preferences during peak fertility (irrespective of whether baby-making is actually on the agenda). A study in 2006 did find that men apparently showing higher “creative intelligence” were favoured at this time [4]. Charlton reasoned that the complexity of a male composer’s music might be considered an indicator of his creativity and capacity for learning complex behaviour, and so this too might affect female sexual choice. He has previously found that ovulation doesn’t seem to affect women’s preferences for complexity of music per se [5]. But what about the composers themselves?

Charlton recruited a group of 1,465 adult women participants for his web-based survey, and divided them into those at low and high risk of conception at the time of testing, based on what they reported about their reproductive cycle. He played them several short melodies, composed for the experiment, of varying degrees of complexity. First he asked some of the participants to rate the melodic complexity, to ensure that they could do this reliably. Then he asked a different group which of the supposed (male) composers of a pair of melodies of different complexity they would prefer as a short- or long-term sexual partner. A significant number showed a greater preference for the “more complex” composer – but only in the high-conception-risk group, and only as a short-term partner (implying sex right now, when the chance of conception is high).

Now, numbers are numbers: it seems that something connected to the reproductive cycle was indeed changing preferences in that situation. But what? The findings, Charlton says, “support the contention that women use (or ancestrally used) the ability of male composers to create complex music as criteria for male choice.” That would in turn suggest that musical complexity itself arose from an “arms race” in which male musicians increasingly strove to prove their prowess and woo a mate. Charlton suggests that future work might examine whether the sexual preferences also work for a reversal of sexes, with women making the music. It would be interesting to find out, although there is no reason to suppose that sexual selection is gender-symmetrical, and in fact in general it is not. The fact that most music is produced by men [6] is actually what you’d expect for sexually selective trait [7] (although that’s not to say that it’s an explanation).

Yet while Charlton’s findings are intriguing, there are many reasons not to jump to conclusions. For example, the most complex music, according to some measures [8], is Indonesian gamelan, which is among the most social, devotional and non-sexualized of all world music.



There is little reason to think that music has displayed a steady trend towards greater complexity. And it is very hard to untangle a listener’s preferences for a composer from their preferences for the actual music. The latter in general shows a peak of ‘preferred complexity’, beyond which preference declines (as the Beatles’ music got steadily more complex, their sales declined [9]). And this is even before we get into the murky issue of how cultural overlays will colour the assumptions that women might make about fictitious composers, based on a tiny snippet of ‘their’ tunes. More work required, then – or in other words, if music be the food of love, play on!

References
1. B. D. Charlton, Proceedings of the Royal Society B, advance online publication (2014). [Here] [Be patient - this might take a while to become live on the PRSB site...]
2. N. L. Wallin, B. Merker & S. Brown (eds), The Origins of Music. MIT Press, Cambridge, 2000.
3. V. A. Sluming & J. T.Manning, Evolution and Human Behavior 21, 1-9 (2000). [Here]
4. M. Haselton & G. Miller, Human Nature 17, 50-73 (2006). [Here]
5. B. D. Charlton, P. Filippi & W. T. Fitch, PLoS ONE 7, e35626 (2012). [Here]
6. G. F. Miller, in ref. 1, p. 329-360. [preprint available here]
7. D. M. Buss & P. Schmitt, Psychological Review 100, 204-232 (1993). [Here]
8. H. D. Jennings, P. Ch. Ivanov, A. M. Martins, P. C. da Silva & G. M. Viswanathan, http://arxiv.org/abs/cond-mat/0312380 (2003).
9. T. Eerola, T. & A. C. North, in Proceedings of the 6th International Conference of Music Perception and Cognition, eds C. Woods, G. Luck, R. Brochard, F. Seddon & J. Sloboda. Keele University, 2000.

Whatever happened to beautiful instruments?

Have scientific instruments lost their soul? In preparing a schools talk for next week on beautiful experiments, I have been perusing the images online at the very fabulous Museo Galileo in Florence, where I once spent a very happy afternoon. Here are just a few of the very lovely instruments and apparatus that scientists used to use, which are far more beautiful than they really had any call to be. These days scientists have to make do with stuff like this:

which no doubt does the job, but does it inspire you? Below is what I’d like to see return – not the devices themselves, but the spirit in which they were made. Why shouldn’t labs be beautiful?

Hey hey mama

It gladdens my heart to see Jimmy Page with his double-neck guitar on the pages of a science magazine, even in Italian. So it is with the March-April issue of Sapere, where the second of my “music instinct” columns has now appeared. Here it is.

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Attempts to explain how music moves us generally have only one big idea on which to draw. But it’s a good one, and is surely a big part of the answer. When in 1956 the musicologist and composer Leonard Meyer published his book Meaning and Emotion in Music, he was one of the first people to move beyond the cool, formal analysis of musical structure and try to get at why music can make us dance, jump for joy, or break down in tears.

Meyer suggested that it’s all to do with setting up expectations and then violating or postponing their resolution. We think the music is going to do one thing, but it does another – or perhaps it does what we expect, but not quite when we expect it. The unexpected creates a feeling of tension, which might be experienced as excitement. And if that tension is then released, say by the final closing chord of a piece, we feel all the more satisfaction from the delayed gratification. Even the simple rallentando slowing at the end of a Chopin prelude will work that magic.

I’ll give several examples in the forthcoming columns of how this violation of expectation can be played with to raise the emotional temperature, sometimes with exquisite results. Here I want to look at rhythm. This is one of the easiest ways to set up an expectation, because we expect rhythm almost by definition to be repetitive and predictable.

So when it isn’t, we get a thrilling shock. The classic example is Stravinsky’s Rite of Spring, in particular the “Dance of the Adolescents” section. A repeated chord beats away in an insistent pulse – but with an emphasis that shifts with every bar, first on the second beat of the bar, then the first, first again, then second… We never guess when it is coming, so each time it delivers an electrifying jolt.

These unexpected emphases enliven all sorts of music – in jazz, they appear as syncopation, where the beat seems to jump in early and make the rhythm swing. But there are other ways of playing with rhythmic expectation too. Take Led Zeppelin’s song “Black Dog”, where the instrumental riff sounds easy until you try to play it. What’s going on – have they added an extra beat or something? But no, John Bonham’s drums are still ticking away four beats to the bar. The surprising complexity comes from the fact that the guitar riff doesn’t actually fit into this four-beat bar – it has an extra half note. So as it is repeated, it begins and ends in a different place in each bar. The result of these imperfectly overlapping rhythmic structures is disorientating where you think it should be simple. That way, it forces us to pay attention and gives the song a kind of coiled tension and urgency. Stravinsky, I like to think, would have approved.

Particle Fever is aptly named

Here’s the thing. Director and former particle physicist Mark Levinson has made a film, Particle Fever, about the finding of the Higgs particle by the LHC. That’s good news. And it sounds appealing – no omniscient narrator, just the scientists telling the tale. And there are plenty of female physicists in it. But… Here is Levinson on why his background was useful for doing this job: “In some senses, physics hadn’t changed that much since I got out of it in the 80s, because they didn’t have the LHC.” There’s a word missing in that sentence, Mark: “particle”. Particle physics hasn’t changed that much – and to say so is not a great endorsement of your former discipline. But this equating of “physics” with “particle physics” not only plays along with the media myth that the only thing worth noting in physics is what is going on at CERN, but also explains outbursts like this one I received from a (non-particle) physicist recently: “Perhaps the poster child for overselling science should be high-energy physics. They oversold the most expensive toys that physicists have ever produced: high-energy particle accelerators… their arrogance when they talk about ‘the god particle’ and ‘the most important problems’ is disappointing.” I’ve heard similar things from other frustrated physicists. Perhaps Levinson is not now a spokesperson for the particle-physics community, but he does it no favours in this remark.

And it’s evidently not a one-off slip. Later he suggests that there is some fundamental division (in physics) between theorists and experimentalists, along the following lines: “A theorist can wake up in the morning, suddenly erase an equation and rewrite it. An experimentalist, meanwhile, has been working on building a machine for 10 years to prove that theory.” This is not remotely true outside of particle physics – not only could most experimental physicists ill afford to spend 10 years working on building a machine (even if they had to) without having their funding dry up, but most physicists I know work on theory and experiment at the same time.

It is hard not to feel a churl if you express some reservations about the jamboree around the Higgs – but when you see that this circus has apparently convinced some outsiders that the discovery of the Higgs was the most important event in science in the past 100 years, it seems right to feel a twinge of concern. That’s part of the reason I wrote this article. CERN is a blast, the Higgs news was mighty fine, and Peter Higgs deserved the Nobel. But can we please keep a sense of proportion, both about the importance for physics and the whole issue of what physics is?

As for Levinson, he redeems himself by planning – if I read the signs right – to make a film about Denis Noble’s book The Music of Life. I look forward to that.

The physics of marathons

Here, just in time for the London Marathon, is my latest piece for BBC Future. And now I know where the cover of Critical Mass came from.

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Around 40,000 people will run the London Marathon on 13 April this year. But if you’re a serious long-distance runner, don’t come with high expectations. “I have to admit to being completely frustrated by the congestion and for 18-19 miles was just dodging people and being held up”, one participant grumbled after the 2012 event. “I had to overtake a lot of people and ended up with bruised forearms from all the elbows”, said another. “People couldn't let you past for a lot of the way.”

There’s no getting away from it – mass running events like this are likely to be congested. But could the crowding problems be reduced, without restricting the number or calibre of participants? The issue here differs rather little from one that has received far more attention: how to optimize traffic flow on our roads. And while the stakes on the road are much higher – congestion comes at considerable cost in pollution, economic losses and personal inconvenience, while a collision could leave you with far worse than a bruised arm – nonetheless there can also be real dangers from bottlenecks and jams in marathons.

This is why Martin Treiber of the Technical University of Dresden has set out to devise computer models that can predict the flows of participants in marathons and mass cross-country skiing events. Treiber has previously developed models for understanding road traffic flows, and he says that these can be adapted in relatively straightforward ways to capture the essential details of how runners and skiers behave en masse.

One of the first attempts to model traffic flow was made in the 1950s by James Lighthill, an expert on fluid flow, and his collaborator Gerard Whitham of Manchester University. They considered the traffic as a kind of liquid flowing down a pipe, and looked at how the flow changes as the fluid gets denser. At first the flow rate – the amount of stuff you can pump through the pipe in a given time – increases as the density increases, since you simply get more stuff through in the same period of time. But if the density becomes too high, there’s a risk of blockages occurring, and then the flow rate plummets – you have a jam.

Treiber’s model of a marathon, described in a preprint, invokes this same principle that the flow rate first increases and then decreases as the density of runners increases, thanks to an abrupt switch from free to congested flow. He assumes that there is a range of different preferred speeds for different runners, which each sustains throughout the race. With just these ingredients, Treiber can calculate the flow rate of runners, knowing the ‘carrying capacity’ at each point on the route. For example, when the route narrows at bottlenecks, so that the maximum ‘free flow’ rate is lower, the model predicts how congestion might develop and spread elsewhere.

This allows Treiber to figure out how congestion might depend on the race conditions – for example, for different starting procedures. Some marathons start by letting all the runners set off at once (which means those at the back have to wait until those in front have moved forward). Others assign runners to various groups according to ability, and let them start in a series of waves.

Treiber has applied the model to the annual Rennsteig half-marathon along a hiking trail in the Thüringian Forest of central Germany, which attracts around 6,000 participants. In 2013, because the police were no longer willing to close a road to ensure that runners could cross safely, the traditional route had to be altered. It could pass either over a 60m wooden hiking bridge or through a tunnel. Treiber used his model to predict the likely congestion incurred in the various options. If the bridge were to be used, it was important to ensure it did not get too overloaded with runners – a danger if bottlenecks ahead of the bridge spill back onto it. The model predicted that a mass start would certainly risk this, but so, to a lesser degree, would wave starts (which the Rennsteig uses). Only by moving the starting point further back from the bridge could the danger be avoided – and even then, if some of the numbers assumed in the model were only slightly inaccurate, there was still a risk of jams reaching the bridge.

Treiber and his coworkers found that no dangerous congestion seemed likely for the tunnel route. The run organizers consulted with Treiber’s team, and eventually chose this option. They also adopted the team’s recommendation for a wave start with delays of about 150 seconds between waves.

Treiber and his coworkers have adapted his model to describe mass skiing events such as the cross-country Vasaloppet hosted each year in Sweden, a 90-km race that draws around 15,000 participants. This is a more complicated situation to model. Partly that’s because the speed of the skiers can depend quite dramatically on the slope of the course, especially when it is uphill. Treiber built this explicitly into his model, deducing the gradient of the course from Google Maps and applying rules that describe how speed depends on slope. He also included lane-changing rules, since the entire course is divided into well-defined lanes. His computer simulations predicted that massive jams, delaying participants by up to 40 minutes, would form where the route has a steep uphill gradient – just as is seen in the real event. The Vasaloppet has a mass start – but Treiber says that if it could be persuaded to adopt a wave start, with 5-minute delays between waves, all the jams would disappear. Whether the organizers will accept this “wisdom for the crowd” remains to be seen.

Sceptical hauntings

The aforementioned A Natural History of Ghosts by Roger Clarke (which I highly recommend) informs me that Einstein once wrote “Even if I saw a ghost, I wouldn’t believe it.” I know what he means. I once had an experience that can only reasonably be called paranormal, and I don’t believe it. The fact is, though, I don’t disbelieve it either. I don’t see how I can. It remains a mystery, and I can only say that I have almost no idea how to interpret it – which, to be honest, is something I rather like, even if it leaves me feeling a little like the protagonist in Alan Lightman’s novel Ghost.

As a teenager, Clarke went hunting for ghosts around the Isle of Wight, where he lived at what I suspect must have been much the same time as I did. But perhaps the grand manor houses where he seems to have spent his childhood were not the only or even the best places to search. I don’t actually recall the exact, or even the approximate location of the house in which, aged around 15, I had my weird experience, but I think it was in Shanklin, and I do know that it was an unremarkable terraced house probably dating from no further back than the 1950s. It belonged to a relative, maybe an aunt, of one of the friends with whom I had gone to a party, and who had bravely agreed to lend their floor to three teenaged boys after they had undoubtedly consumed more alcohol than was wise or even legal. It was around Christmas time, and I remember there was a decorated tree in the living room (definitely a “living room”, nothing as refined as a “sitting room”) where we laid out our sleeping bags.

So yes, we had been drinking, but not into a stupor, and I remember feeling fairly coherent when we turned out the lights in the early morning. There may well be a perfectly rational and natural explanation for all of this, but I won’t accept that it was simple inebriation.

This “haunting” was entirely within my own mind, which is why I am kind of happy to regard it as a mental phenomenon of some sort. But it was like none I have had before or since. As a child and young person I was plagued by nightmares, but I never knew any other occasion when I awoke from them doubting that this is all they were. What happened as I was sleeping was nothing like a nightmare. For a start, I was fully aware of where I was: lying in a sleeping bag next to my friends on a borrowed floor. But what I felt – and it came upon me quite suddenly – was that I was being taken over and possessed by an incredibly malign force. And it had the character of a personality, one that was raging wildly. I could hear a voice in my head, intoning words that I couldn’t recognize but which sounded to be spoken in something approaching a Scottish accent, and utterly fearsome and demonic. Here’s the worst thing: I could feel my whole body inside my sleeping bag, and it felt as though it was being emptied out, shrivelling up into a dry husk as this “thing” took it over.

Then I woke up, and in an almost parodic manner I sat bolt upright, eyes wide open, and said “Ah!”. I was terrified. But there were by friends, sleeping soundly next to me. I have not the slightest suspicion that this was any kind of prank played by them, and I don’t see how they could have created the mental effect anyway.

Well, I suppose I thought, that was a very scary experience indeed. But here I am, in this mundane little house, and there’s evidently nothing strange going on here. So after a time, I lay down and went back to sleep.

That was a mistake. I’d scarcely nodded off when the whole thing happened again: the same fury and sense of malevolence, the same feeling that I was being possessed and crushed within my own body. That’s the way to put it: as though any shred of my own self was to be pulverized out of existence.

And again I “awoke with a start”, in that phrase that children’s writers seem unable to do without. This time, sitting upright and seeing everything as before, I thought: sod it, I am not going to risk going back to sleep. I’ll sit the night out. But I couldn’t. At some point I drifted back into slumber.

This time it started differently: not with that sense of frantic raving and anger, but insidiously, as though this “thing” had decided this time that I would be more effectively eliminated by stealth. But I knew it was happening, just as I knew I was lying there helpless. Then I “heard” a distinct phrase in my head, and I can only suppose it was the voice of some part of me. It said this: “What do you think it wants?”

I have never forgotten those words, especially because they were evidently regarded as a provocation. The moment they “sounded”, the “thing” returned in full, furious force, and there I was again, becoming this shrivelled husk.

But I woke up again. And this time I’d really had enough. I was beside myself with fear. Why didn’t I wake up one of my friends? What, a teenager, admitting to his mates that he was scared he was being possessed? No, I wasn’t going to risk that. Instead I was determined that this time I’d stay awake until dawn. And I nearly did, because I remember that there was the first dim light starting to appear through the curtains, and the birds were starting to tweet, when I fell asleep again, this time into an untroubled slumber.

So there you have it. I was too confused, too shy and embarrassed, to say anything in the morning or to make any enquiries about the house or the people who lived there. I wish I had, but there you go.

All this ghost business comes from the research I have been doing for my next book, Invisible. And I remember reading somewhere in the course of that research about a well attested brain disturbance that can create the sensation of a weight pressing on the chest – purportedly an explanation for some nocturnal “manifestations” that have been described through the ages, perhaps like the one depicted so provocatively in Fuseli’s famous image. Mine is I suppose a little similar, although it went considerably beyond that. What really perplexes me is the triple repeat, with episodes of clear and even lucid waking in between. I have, once or twice, awoken only to slip back into something like the same dream – one can never be sure how “similar” it really is, given the way dreams leave odd imprints on the memory. But I’ve never known anything even remotely like this.

It’s why I like the fact that Clarke remains open-minded in his book and doesn’t try to explain everything away, even though he reports the known hoaxes, the possible role of ultrasound, and so forth. I think he probably believes in ghosts, in a way that I can’t – for one thing, each manifestation seems too attuned to the preconceptions and ethos of its times. But something very strange happened to me all those years ago, and I simply don’t know what it was.

Bleary-eyed in Madrid: on Catholicism, curiosity, and ghosts

There is probably some unwritten rule somewhere that you should never blog at 5 in the morning, but I see no real prospect that the Atletico Madrid fans celebrating their victory over Barcelona in the square outside are going to stop singing before dawn. Ah well, it is just one of those things you have to love about Spain. Also, I doubtless drunk too much coffee in this interview with El Pais during what is now yesterday. The headline (and ensuing comment) reminds me, as did a nice dinner with the folks at the Fundacion Telefonica discussing Franco and Catholicism, that some things are going to be perceived differently down here in the south.

Needless to say, I’m not sure that I will exactly be retiring from football in order to spend more time with the Internet… And it seems that there is no way now that I’m going to prevent people forever suggesting that I am/was the “editor of Nature”. But Javier was a very nice chap, and I’m not complaining. Anyway, this is all an excuse to mention the lovely quote that I found yesterday in Roger Clarke’s wonderful A Natural History of Ghosts. He says that the shade of the dead brother of Robert Boyle, Lord Orrery, once appeared to Boyle’s sister Lady Ranelagh. Boyle, one of the key figures in my book Curiosity, responded to this news in typical fashion by asking his sister to pose a series of metaphysical questions to the ghost when it next appeared. She duly did so, whereupon the ghost replied “I know these questions come from my brother. He is too curious.”

I was delighted to find that Roger Clarke, like me, grew up on the Isle of Wight, and so knows all about the local ghosts there. I have another one for him, of which more later.

Ballard - always head of his time

My enjoyment of eulogies for J. G. Ballard, like this one in the Guardian on the 5th anniversary of his death, is always tempered by a sense of bitterness. For I can’t help feeling some resentment at the way the literary world now embraces this writer who was considered infra dig when I devoured everything he wrote 40 years ago. Even as a callow and barely literate teenager, I had a sense – which I could never then have articulated – that his works were far more relevant a window on the modern (by then almost postmodern, I suppose) age than the majority of works celebrated by what I now imagine was a literary community of a largely Leavisite mindset. Deborah Levy has it quite right in this article that the classification of Ballard as “science fiction” was really an attempt to tame and marginalize a writer who was too edgy, strange and visionary for that kind of sensibility. I think young Ballardians like me could intuit that writers like Michael Moorcock, Philip K. Dick, Kurt Vonnegut and most of all Ballard were working in a different kind of genre from Asimov and Clarke, and that the superficial sci-fi traits that some of them used from time to time were merely tools that suited their ulterior purpose. I surely read books like The Atrocity Exhibition with as threadbare a set of cultural references as I brought to my uncomprehending forays on Dostoevsky, having no real notion of who this Ralph Nader and Ronald Reagan were (that was the 1970s) and little idea of why Jackie Kennedy represented much more than a dead president’s wife (specifically, the harbinger of the modern age of celebrity). In short, a lot of it went right over my head. But I read on, feeling I suppose that this stuff was going to matter, that it was worth more than the values of the day seemed to allow.

What has changed, I suppose, is that the literary community is now populated by folks from a similar time and attitude as mine – Self, Kunzru, Mieville – for whom that kind of “speculative fiction” was as valid as the old, approved canon. I think this is progress. But it would be foolish to imagine that they too, we too, are not now overlooking and snobbishly dismissing writers who will turn out, in retrospect, to be the true prophets of our times.

How the universe got blown up

No one particularly needs me to tell them about the BICEP2 results, given that so many others have already done so very nicely. But here is the way I put it in the latest issue of Prospect, where I wanted to try to put the findings within the broader picture of our unfolding cosmological view over the past century. That’s why I mention dark energy and the cosmological constant, even though one can perfectly well explain inflation without that. I’d contend that, if this work bears up, we’ll see the major landmarks as:
1912/1919: general relativity proposed and ‘confirmed’
1927/29: the Big Bang and cosmic expansion predicted and confirmed
1965: the CMB detected (and a minor landmark with the 1992 COBE results)
1998: the accelerating expansion of the universe
2014: inflation and gravitational waves ‘confirmed’ (?)
Who’s going to put money on Guth and Linde for the Nobel? Probably needs an independent confirmation first, though.

I feel like I spend a fair bit of time these days trying to bring a critical eye to the excesses of science boosterism. So how nice it is to be able for once to relish the sheer joy of how fab science can be. That was an exciting week. And if this piece is a little loose around the edges, forgive me – it had to be knocked out essentially overnight.

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The discovery reported on 17 March by a US-led team of scientists will join the small collection of epochal moments that, at a stroke, changed our conception of what the universe is like. It offers evidence that, within an absurdly small fraction of a second after the universe was born in the Big Bang, it underwent a fleeting period of very rapid growth called inflation. This left the fabric of spacetime ringing with “gravitational waves”, which are predicted by Albert Einstein’s theory of general relativity but have never been seen before.

Finding evidence for either inflation or gravitational waves would each be a huge deal on its own. Confirming both together will leave cosmology reeling, and – barring some alternative explanation for the data, which looks unlikely – it is inconceivable that they will fail to win a Nobel prize in their own right and probably to motivate another for the theories they support. According to astrophysicist Sean Carroll of the California Institute of Technology in Pasadena, the results supply “experimental evidence of something that was happening right when our universe was being born”. That we can find this nearly fourteen billion years after the event is astonishing.

The discovery was made by a team led by John Kovac of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, using the Background Imaging of Cosmic Extragalactic Polarization (BICEP2) telescope located at the South Pole. It’s the kind of milestone in observational cosmology that comes only once every few decades, and fits perfectly into the narrative created by the previous ones.

We might start in 1919, when the British astronomer Arthur Eddington observed, from the island of Principe, the bending of starlight passing by the sun during a total solar eclipse. This confirmed Einstein’s prediction that gravity distorts spacetime, forcing light to trace an apparently curved path. The discovery made Einstein internationally famous.

Because of this effect of gravity, general relativity predicts that violent astrophysical events involving very massive objects – an exploding star (supernova), say, or two black holes colliding – can excite waves in spacetime that travel like ripples in a pond: gravitational waves. Scientists were confident that these waves exist, but detecting them is immensely difficult because the distortions of spacetime are so small, changing the length of a kilometre by a fraction of the radius of an atom. Several gravitational-wave detectors have been built around the world to spot these distortions from a passing gravity wave via interference effects in laser beams shone along long, straight channels and bouncing off mirrors at the end. They haven’t yet revealed anything, but the hope is that gravitational waves might eventually be used just like radio waves or X-rays to detect and study distant astronomical events.

The BICEP2 findings unite gravitational waves and general relativity with the theory of the Big Bang, for which we need to go back to the second cosmological milestone. In 1929 American astronomer Edwin Hubble reported evidence that the universe is expanding: the further away galaxies are, he said, the faster they are receding from us. Hubble’s expanding universe is just what is expected from an origin in a Big Bang. In fact Einstein had already found that general relativity predicts this expansion, but before Hubble most people believed that the universe exists in a static steady state, and so Einstein added a term to his equations to impose that. Yet in 1927 a relatively obscure Belgian physicist, George Lemaître, dared to take the theory seriously enough to predict a Big Bang. Hubble’s data confirmed it.

Yet it wasn’t until 1965 that one of the key predictions of the Big Bang theory was verified. Such a violent event should have left an ‘afterglow’: radiation scattered all across the sky, by now dimmed to a haze of microwaves with a temperature of just a little less than three degrees above absolute zero. While setting up a large microwave receiver to conduct radio astronomy, Arno Penzias and Robert Wilson found that they were picking up noise that they couldn’t eliminate. Eventually they realised it was the fundamental noise of the universe itself: the cosmic microwave background (CMB) radiation of the Big Bang. That’s milestone number three.

Number four came in 1998. While observing very distant supernovae, two teams of astronomers discovered that these objects weren’t just receding from us: they were speeding up. That was a real shock, because most cosmologists thought that the gravitational pull of all the matter in the universe would be slowing down its expansion. If, on the contrary, it is speeding up, then some force or principle seems to be opposing gravity. We call it dark energy, but no one knows what it is.

Einstein had already unwittingly provided a formal answer with his balancing act for getting rid of cosmic expansion: he added to his equations a fudge factor now called the cosmological constant. This amounts to saying that the vacuum of empty space itself has an energy – and because this energy increases as space expands, it can in fact produce an acceleration.

BICEP2’s results now look like milestone number five, and they stitch all these ideas together. The telescope has made incredibly detailed measurements of the CMB, spotting temperature differences from place to place in the sky of just a ten-millionth of a degree. Hence the exotic location: the telescope sits at the Amundsen-Scott South Pole station, 2,800 up on an ice sheet, where the atmosphere is thin, dry and clear, and free of interference from light and radio signals.

For the fact is that the CMB isn’t simply a uniform glow: some parts of the universe are a tiny bit “hotter” than others. This was confirmed in 1992 by observations with the Cosmic Background Explorer (COBE) satellite, which provided the first map of these “anisotropies” (hot and cool spots) in the CMB – and thereby some of the best evidence for the Big Bang itself. Since then the maps have got considerably more detailed.

Yet the puzzle is not so much why the CMB isn’t entirely smooth but why it isn’t even more uneven. A simple theory of a Big Bang in which the universe expanded from a tiny primeval fireball predicts that it should be much more blotchy, consisting of patches that are receding too fast to affect one another. So space should be far less flat and uniform. In 1980 the American physicist Alan Guth proposed that very early in the Big Bang – about a trillion-trillion-trillionth of a second (10**-36 s) after it began – the universe underwent a burst of extremely rapid expansion, called inflation, which took it from much smaller than an atom to perhaps the size of a tennis ball – an expansion of around 10**60-10**80-fold. This would have smoothed away the unevenness. In effect, inflationary theory supposes that there was a short time when the vacuum energy was big enough to boost the universe’s expansion.

Inflation doesn’t smooth out space completely, though. Quantum mechanics insists on some randomness in the pre-inflation pinprick universe, and these quantum fluctuations would have been frozen into the inflated universe, imprinted for example on the CMB. In turn, those variations seeded the gravitational collapse of gas into stars and galaxies – a staggering idea really, that infinitesimal quantum randomness is now writ large and glowing across the heavens. It’s possible to calculate what pattern these quantum fluctuations out to give rise to, and observations of the CMB seem to match it.

All the same, there was no direct evidence for inflation – until now. The theory also predicts that the microwave background radiation should be polarized – its electromagnetic oscillations have a preferred orientation – with a characteristic pattern of twists, called the B-mode. This swirly polarization is what BICEP2 has detected, and there’s no obvious explanation for it except inflation. Cue a Nobel nomination for Guth, and other architects of inflationary theory, in October.

What’s all this got to do with gravitational waves? Cosmic inflation was rather like a shock wave that set the universe quaking with primordial gravitational waves. They have now, 13.8 billion years later, died away to undetectable levels. But they’ve left a fingerprint behind, in the form of the polarized swirls of the CMB, just as ocean waves leave ripples in sand. It seems the only way these swirls could have got there was via gravitational waves.

OK, but where does inflation itself come from? Physicists’ usual response to a question they can’t answer is to invent a particle that does the required job, and give it a snazzy name: neutrino, WIMP, graviton, whatever. Carroll, who now proudly records Kovac among his former students, admits that this is what they’ve done here. “We don’t know what field it is that drove inflation”, he says, “so we just call it the inflaton.”

In other words, just as the photon (a ‘particle of light’) is the agent of the force of electromagnetism, and the Higgs boson was initially postulated as the force field that gave some particles their mass, so the inflaton is the alleged particle behind the force that unleashed inflation. It’s just a name, but here’s the point: it’s a particle whose behaviour, like that of all fundamental particles, must be governed by quantum theory.

And that’s where we really hit the exciting stuff. Confirming these two astonishing ideas, inflation and gravitational waves, is terrific. But they always looked a pretty safe bet. It’s what lies behind them that could be truly revolutionary. For gravitational waves are a product of general relativity, the current theory of gravity. But here they get kicked into existence by an effect of quantum mechanics, orchestrated by the quantum inflaton. In other words, we’re looking at an effect that bridges the biggest mystery in contemporary physics: how to reconcile the ‘classical physics’ of relativity with quantum physics, and thus create a quantum theory of gravity. Sure, BICEP2’s results don’t yet show us how to do that. But how many simultaneous revolutions could you cope with?

Mathematician rewarded for asking the right questions

I do enjoy reporting for Nature on the Abel Prize in maths, as I’ve done for the past several years. The Norwegians are friendly and helpful – there’s not the absolute secrecy associated with the Nobels, and this is just as well, because more often than not you need a fair bit of advance warning to get your head around what the prize is being given for. This year it was a little less challenging, though, because I already knew a small amount about the Abel laureate Yakov Sinai, whose work is really about physics, even if it demands the most exacting maths. As Sinai put it in the phone conversation through which he was informed of the award “mathematics and physics go together like a horse and carriage” – OK, it’s not exactly a catchy quote, but it is very interesting to see physics formulated with such rigour. I remember hearing years ago how mathematicians generally can’t believe what physicists think is a rigorous argument or proof. But I don’t think they feel that way about Sinai’s work. Anyway, here’s the pre-edit of the Nature story.

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Abel Prize laureate has explored physics “with the soul of a mathematician”

The Norwegian Academy of Science and Letters has awarded the 2014 Abel Prize, often regarded as the “maths Nobel”, to Russian-born mathematical physicist Yakov Sinai of Princeton University. The award cites his “his fundamental contributions to dynamical systems, ergodic theory, and mathematical physics.”

Jordan Ellenberg, a mathematician at the University of Wisconsin who presented the award address today, says that Sinai has worked on questions relating to real physical systems “with the soul of a mathematician”. He has developed tools that show how systems that look superficially different might have deep similarities, much as Isaac Newton showed that the fall of an apple and the movements of the planets are guided by the same principles.

Sinai’s work has been largely in the field now known as complex dynamical systems, which might be regarded as accommodating ideal mechanical laws to the messy complications of the real world. While Newton’s laws of motion provide an approximate description of how objects move under the influence of forces in some simple cases – the motions of the planets, for example – the principles governing real dynamical behaviour are usually more complicated. That’s the case for the weather system and atmospheric flows, population dynamics, physiological processes such as heartbeat, and much else.

Sometimes these movements are subjected to random influences, such as the jiggling of small particles by thermal noise. These are called stochastic dynamical processes. The perfect predictability of Newton’s laws might also be undermined simply by the presence of too many mutually interacting bodies, as in fluid flow. For even just three bodies, Newton’s deterministic laws may lead to chaotic behaviour, meaning that vanishingly small differences in the initial conditions can lead to widely different outcomes over long times. This kind of chaos is now known to be present in the orbits of planets in the solar system.

Sinai has developed mathematical tools for exploring such behaviour. He has identified quantities that remain the same even if the trajectories of objects in these complex dynamical systems become unpredictable. His interest in these issues began while he was at Moscow State University in the late 1950s as a student of Andrey Kolmogorov, one of the greatest mathematical physicists of the twentieth century, who established some of the foundations of probability theory.

Sinai and Kolmogorov showed that even for dynamical systems whose detailed behaviour is unpredictable – whether because of chaos or randomness – there is a quantity that measures just how ‘complex’ the motion is. Inspired by the work of Claude Shannon in the 1940s, who showed that a stream of information can be assigned an entropy, Sinai and Kolmogorov defined a related entropy that measures the predictability of the dynamics: the higher the Kolmogorov-Sinai (K-S) entropy, the lower the predictability.

Ellenberg says that, whereas many physicists might have expected such a measure to distinguish between deterministic systems (where all the interactions are exactly specified) and stochastic ones, the K-S entropy showed that in fact there are qualitatively different types of purely deterministic system: those with zero entropy, which can be predicted exactly, and those with a non-zero entropy which are not wholly predictable, in particular chaotic systems.

Invariant measures like the K-S entropy are related to how thoroughly such a system explores all the different states that it could possibly adopt. A system that ‘visits’ all these states more or less equally on average is said to be ergodic. One of the most important model systems for studying ergodic behaviour is the Sinai billiard, which Sinai introduced in the 1960s. Here a particle bounces around (without losing any energy) within a square perimeter, in the centre of which there is a circular wall. This was the first dynamical system for which it could be proved, by Sinai himself, that all the particle’s trajectories are ergodic – they pass through all of the available space. They are also chaotic, in the sense that the slightest difference in the particle’s initial trajectory leads rather quickly to motions that don’t look at all alike.

In these and other ways, Sinai has laid the groundwork for advances in understanding turbulent fluid flow, the statistical microscopic theory of gases, and chaos in quantum-mechanical systems.

The Abel Prize in mathematics, named after Norwegian mathematician Niels Henrik Abel (1802–29), is modelled on the Nobel prizes and has been awarded every year since 2003. It is worth 6 million Norwegian kroner, or about US$1 million.

“I'm delighted that Sinai, whose scientific and social company I enjoy, has won this prize”, says Michael Berry of Bristol University, who has worked on chaotic quantum billiards and other aspects of complex dynamics.

Ellenberg feels that Sinai’s work has demonstrated how, in maths, “a good definition is as important as a good theorem.” While physicists knew in a loose way what they meant by entropy, he says, Sinai has asked “what are we actually talking about here?” This drive to get the right definition has helped him identify what is truly important and fundamental to the way a system behaves.

The value of ambiguity

Here's my latest piece for "Under the Radar" at BBC Future.

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Listen, I’m going to be straight with you. Well, that’s what I’d intended, but already language has got in the way – you’re not “listening” at all, and “straight” has so many meanings that you should be unsure what is going to follow. All the same, I doubt if any of you thought this meant I was going to stand to attention or be rigorously heterosexual. Language is ambiguous – and yet we cope with it.

But surely that’s a bit of a design flaw, right? We use language to communicate, so shouldn’t it be geared towards making that communication as clear and precise as possible, so that we don’t have to figure out the meaning from the context, or are forever asking “Say that again?” Imagine a computer language that works like a natural language – would the silicon chips have a hope of catching our drift?

Yet the ambiguity of language isn’t a problem foisted on it by the corrupting contingencies of history and use, according to complex-systems scientists Ricard Solé and Luís Seoane of the Pompeu Fabra University in Barcelona, Spain. They say that it is an essential part of how language works. If real languages were too precise and well defined, so that every word referred to one thing only, they would be almost unusable, the researchers say, and we’d struggle to communicate ideas of any complexity.

That linguistic ambiguity has genuine value isn’t a new idea. Cognitive scientists Ted Gibson and Steven Piantadosi of the Massachusetts Institute of Technology have previously pointed out that a benefit of ambiguity is that it enables economies of language: things that are obvious from the context don’t have to be pedantically belaboured in what is said. What’s more, they argued, words that are easy to say and interpret can be “reused”, so that more complex ones aren’t required.

Now Solé and Seaone show that another role of ambiguity is revealed by the way we associate words together. Words evoke other words, as any exercise in free association will show you. The ways in which they do so are often fairly obvious – for example, through similarity (synonymy) or opposition (antonymy). “High” might make you think “low”, or “sky”, say. Or it might make you think “drugs”, or “royal”, which are semantic links to related concepts.

Solé and Seoane look at the intersecting networks formed from these sematic links between words. There are various ways to plot these out – either by searching laboriously through dictionaries for associations, or by asking people to free-associate. There are already several data sets of semantic networks freely available, such as WordNet, which use fairly well-defined rules to determine the links. It’s possible to find paths through the network from any word to any other, and in general there will be more than one connecting route. Take the case of the words “volcano” and “pain”: on WordNet they can be linked via “pain-ease-relax-vacation-Hawaii-volcano” or “pain-soothe-calm-relax-Hawaii-volcano”.

A previous study found that WordNet’s network has the mathematical property of being “scale-free”. This means that there is no real average number of links per word. Some words have lots of links, most have hardly any, and there is everything in between. There’s a simple mathematical relationship between the probability of a word having k connections (P(k)) and the value of k itself: P(k) is proportional to k raised to some power, in this case approximately equal to 3. This is called a power law.

A network in which the links are apportioned this way has a special feature: it is a “small world”. This means that it’s just about always possible to find shortcuts that will take you from one node of the network (one word) to any other in just a small number of hops. It’s the highly connected, common words that provide these shortcuts. Some social networks seem to have this character too, which is why we speak of the famous “six degrees of separation”: we can be linked to just about anyone on the planet through just six or so acquaintances.

Solé and Seoane now find that this small-world feature of the semantic network is only a small world when it includes words that have more than one meaning (in linguistic terms this is called polysemy). Take away polysemy, the researchers say, and the route between any pair of words chosen at random will be considerably longer. By having several meanings, polysemic words can connect clusters of concepts that otherwise might remain quite distinct (just as “right” joins words about spatial relations to words about justice). Again, much the same is true of our social networks, which seem to be “small” because we each have several distinct roles or personas – as professionals, parents, members of a sports team, and so on, meaning that we act as a link between quite different social groups - the web is easy to navigate.

The small-world character of social networks helps to make them efficient at spreading and distributing information. For example, it makes them “searchable”, so that if we want advice on bee-keeping, we might well have a friend who has a bee-keeping friend, rather than having to start from scratch. By the same token Solé and Seaone think that small-world semantic networks make language efficient at enabling communication, because words with multiple meanings make it easier to put our thoughts into words. “We browse through semantic categories as we build up conversations”, Seoane explains. Let’s say we’re talking about animals. “We can quickly retrieve animals from a given category (say reptiles) but the cluster will soon be exhausted”, he says. “Thanks to ambiguous animals that belong to many categories at a time, it is possible to radically switch from one category to another and resume the search in a cluster that has been less explored.”

What’s more, the researchers argue that the level of ambiguity we have in language is at just the right level to make it easy to speak and be understood: it represents an ideal compromise between the needs of the speaker and the needs of the listener. If every single object and concept has its own unique word, then the language is completely unambiguous – but the vocabulary is huge. The listener doesn’t have to do any guessing about what the speaker is saying, but the speaker has to say a lot. (For example, “Come here” might have to be something like “I want you to come to where I am standing.”) At the other extreme, if the same word is used for everything, that makes it easy for the speaker, but the listener can’t tell if she is being told about the weather or a rampaging bear.

Either way, communication is hard. But Solé and Seoane argue that with the right amount of polysemy, and thus ambiguity, the two can find a good trade-off. What’s more, it seems that this compromise brings the advantage also of “collapsing” semantic space into a denser net that allows us to make fertile connections between disparate concepts. We have even arguably turned this small-world nature of ambiguity into an art form – we call it poetry. Or as you might put it,
Words, after speech, reach
Into the silence. Only by the form, the pattern,
Can words or music reach
The stillness.

Reference: R. V. Solé & L. F. Seoane, preprint http:/www.arxiv/org/1402.4802 (2014).

Some enlightenment on Giordano Bruno

I hear that the relaunched Cosmos TV series has included a little hagiography of Giordano Bruno as a martyr to Copernican science, and I sigh. If I was a sensible chap, I would simply accept this myth is never now going to be squashed, because it seems to be too important to many people as a means of “showing” how the Roman Church was determined to stamp out the kind of independent and anti-dogmatic thought that supposedly gave rise to modern science. In short, Bruno fills the same martyr’s role here as early Christians needed to sustain their own faith.

But I am not a sensible chap, because I persist with this fantasy that one day everyone will be persuaded to go back and look at the history and see that this portrayal of Bruno is a (relatively) modern invention – an aspect of the nineteenth-century Draper-White narrative that pitched science in head-on combat with the Church. I am foolish enough to imagine that what I wrote in my book Curiosity is actually going to be read and heeded:
“The Neapolitan friar Giordano Bruno had an arrogant and argumentative nature that was bound to get him into serious trouble eventually, although if he had not happened to promote Copernican cosmology it is doubtful that he would command any greater fame today than the many other intellectual vagabonds who wandered Europe during the Counter-Reformation. It seems a vain hope that Bruno should ever cease to be the ‘martyr to science’ that modern times have made of him; maybe we must resign ourselves to the words spoken by Brecht’s Galileo: ‘Unhappy the land where heroes are needed.’
The fact is that Bruno’s Copernicanism is not mentioned in the charges levelled against him by the Inquisition in 1576, nor the denunciation of 1592 that led to his imprisonment and lengthy trial. Of the heretical accusations that condemned him to be burnt at the stake in 1600, only two are still recorded, which relate to obscure theological matters. He held many opinions of which the Church disapproved deeply, on such delicate matters as the Incarnation and the Trinity, not to mention having a long history of associating with disreputable types. Bruno’s death stains the Church’s record of tolerance for free thought, but says little about its attitude to science. There is nothing in Bruno’s espousal of a world soul, or his long discourses on demons and other spiritual beings, or his unconventional system of the elements, that makes him so very unusual for his times – but nothing either that qualifies him for canonization in the scientific pantheon.”

But then – praise be! – I see that others have done the job already, and better than I could. Corey Powell at Discover magazine has set the record straight on Bruno, and attacking this old Whig view of science history. Meg Rosenburg has posted a nice piece on Bruno too. And best of all, Rebekah Higgitt has written a masterful article in her Guardian blog about why this kind of appropriation of history to serve our modern agenda is invariably false and damaging to the historical record. As she puts it, “Historical figures who lived in a very different world, very differently understood, cannot be turned into heroes who perfectly represent our values and concerns without doing serious damage to the evidence.” And this is really the point, for I’m tired and, I fear, a little cross at scientists who seem to think that being scrupulous with the evidence only applies to science and not to something as wishy-washy as the humanities. So hurrah to all three of you!

And I couldn’t help but be struck by how, at the same time, we have Brendan O’Neil (who I can’t say I always agree with) taking Richard Dawkins to task by pointing out how the Enlightenment was not, as many alleged champions of “Enlightenment values” like to insist today, about attacking religion, but rather about demanding religious tolerance and the freedom to worship as one pleases. But Brendan doesn’t take this point far enough. For the one thing Enlightenment heroes like Voltaire and Rousseau could not abide was atheism. The Enlightenment is as abused an historical notion as Bruno’s “martyrdom” is – by much the same people and for much the same reasons. And so this motivates me to post here what I said about all this at the How The Light Gets In festival at Hay-on-Wye last summer, as part of a debate on optimism, pessimism and the legacy of the Enlightenment. Here it is.

Yes, I’m fool enough to think that this might stop some folk from banging on about “Enlightenment values.” And yes, I know that this is deeply irrational of me.

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“Nasty, brutish and short”: How The Light Gets In Festival, panel discussion, 1st June 2013, Hay-on-Wye.

I’ve been trying to parse the title of this discussion ever since I saw it. The blurb says “The Enlightenment taught us to believe in the optimistic values of humanism, truth and progress” – but of course the title, which sounds a much more pessimistic note, comes from Thomas Hobbes’ Leviathan, and yet Hobbes too is very much a part of the early Enlightenment. You might recall that it was Hobbes’ description of life under what he called the State of Nature: the way people live if left to their own devices, without any overarching authority to temper their instincts to exploit one another.

That scenario established the motivation for Hobbes’ attempt to deduce the most reliable way to produce a stable society. And what marks out Hobbes’ book as a key product of the Enlightenment is that he tried to develop his argument not, as previous political philosophies going back to Plato had done, according to preconceptions and prejudices, but according to strict, quasi-mathematical logic. Hobbes’ Commonwealth is a Newtonian one – or rather, to avoid being anachronistic, a Galilean one, because he attempted to generalize his reasoning from Galileo’s law of motion. This was to be a Commonwealth governed by reason. And let me remind you that what this reason led Hobbes to conclude is that the best form of government is a dictatorship.

Now of course, this sort of exercise depends crucially one what you assume about human nature from the outset. If, like Hobbes, you see people as basically selfish and acquisitive, you’re likely to end up concluding that those instincts have to be curbed by drastic measures. If you believe, like John Locke, that humankind’s violent instincts are already curbed by an intrinsic faculty of reason, then it becomes possible to imagine some kind of more liberal, communal form of self-government – although of course Locke then argued that state authority is needed to safeguard the private property that individuals accrue from their efforts.

Perhaps the most perceptive view was that of Rousseau, who argued in effect that there is no need for some inbuilt form of inhibition to prevent people acting anti-socially, because they will see that it is in their best interests to cooperate. That’s why agreeing to abide by a rule of law administered by a government is not, as in Hobbes’ case, an abdication of personal freedom, but something that people will choose freely: it is the citizen’s part of the social contract, while the government is bound by this contract to act with justice and restraint. This is, in effect, precisely the kind of emergence of cooperation that is found in modern game theory.

My point here is that reasoning about governance during the Enlightenment could lead to all kinds of conclusions, depending on your assumptions. That’s just one illustration of the fact that the Enlightenment doesn’t have anything clear to say about what people are like or how communities and nations should be run. In this way and in many others, the Enlightenment has no message for us – it was too diverse, but more importantly, it was much too immersed in the preoccupations of its times, just like any other period of history. This is one reason why I get so frustrated about the way the Enlightenment is used today as a kind of shorthand for a particular vision of humanity and society. What is most annoying of all is that that vision so often has very little connection with the Enlightenment itself, but is a modern construct. Most often, when people today talk about Enlightenment values, they are probably arguing in favour of a secular, tolerant liberal democracy in which scientific reason is afforded a special status in decision-making. I happen to be one of those people who rather likes the idea of a state of that kind, and perhaps it is for this reason that I wish others would stop trying to yoke it to the false idol of some kind of imaginary Enlightenment.

To state the bleedin’ obvious, there were no secular liberal democracies in the modern sense in eighteenth century Europe. And the heroes of the Enlightenment had no intention of introducing them. Take Voltaire, one of the icons of the Enlightenment. Voltaire had some attractive ideas about religious tolerance and separation of church and state. But he was representative of such thinkers in opposing any idea that reason should become a universal basis for thought. It was grand for the ruling classes, but far too dangerous to advocate for the lower orders, who needed to be kept in ignorance for the sake of the social order. Here’s what he said about that: “the rabble… are not worthy of being enlightened and are apt for every yoke”.

What about religion, then? Let’s first of all dispose of the idea that the Enlightenment was strongly secular. Atheism was very rare, and condemned by almost all philosophers as a danger to social stability. Rousseau calls for religious tolerance, but not for atheists, who should be banished from the state because their lack of fear of divine punishment means that they can’t be trusted to obey the laws. And even people who affirm the religious dogmas of the state but then act as if they don’t believe them should be put to death.

Voltaire has been said to be a deist, which means that he believed in a God whose existence can be deduced by reason rather than revelation, and who made the world according to rational principles. According to deists, God created the world but then left it alone – he wasn’t constantly intervening to produce miracles. It’s sometimes implied that Enlightenment deism was the first step towards secularism. But contrary to common assertions, there wasn’t any widespread deist movement in Europe at that time. And again, even ideas like this had to be confined to the better classes: the message of the church should be kept simple for the lower orders, so that they didn’t get confused. Voltaire said that complex ideas such as deism are suited only “among the well-bred, among those who wish to think.”

Well, enough Enlightenment-bashing, perhaps – but then why do we have this myth of what these people thought? Partly that comes from the source of most of our historical myths, which is Victorian scholarship. The simple idea that the Enlightenment was some great Age of Reason is now rejected by most historians, but the popular conception is still caught up with a polemical view developed in particular by two nineteenth-century Americans, John William Draper and Andrew Dickson White. Draper was a scientist who decided that scientific principles could be applied to history, and his 1862 book The History of Intellectual Development in Europe was a classic example of Whiggish history in which humankind makes a long journey out of ignorance and superstition, through an Age of Faith, into a modern Age of Reason. But where we really enter the battleground is with Draper’s 1874 book History of the Conflict between Religion and Science, in which we get the stereotypical picture of science having to struggle against the blinkered dogmatism of faith – or rather, because Draper’s main target was actually Catholicism, against the views of Rome, because Protestantism was largely exonerated. White, who founded Cornell University, gave much the same story in his 1896 book A History of the Warfare if Science with Theology in Christendom. It’s books like this that gave us the simplistic views on the persecution of Galileo that get endlessly recycled today, as well as myths such as the martyrdom of Giordano Bruno for his belief in the Copernican system. (Bruno was burnt at the stake, but not for that reason.)

The so-called “conflict thesis” of Draper and White has been discredited now, but it still forms a part of the popular view of the Enlightenment as the precursor to secular modernity and to the triumph of science and reason over religious dogma.

Bur why, if these things are so lacking in historical support, do intelligent people still invoke the Enlightenment trope today whenever they fear that irrational forces are threatening to undermine science? Well, I guess we all know that our critical standards tend to plummet when we encounter idea that confirm our preconceptions. But it’s more than this. It is one thing to argue for how we would prefer things to be, but far more effective to suggest that things were once like that, and that this wonderful state of affairs is now being undermined by ignorant and barbaric hordes. It’s the powerful image of the Golden Age, and the rhetoric of a call to arms to defend all that is precious to us. What seems so regrettable and ironic is that the casualty here is truth, specifically the historical truth, which of course is always messy and complex and hard to put into service to defend particular ideas.

Should we be optimistic or pessimistic about human nature? Well – big news! – we should be both, and that’s what history really shows us. And if we want to find ways of encouraging the best of our natures and minimizing the worst, we need to start with the here and now, and not by appeal to some imagined set of values that we have chosen to impose on history.