Category Archives: Physics

Like, Wow! – The search for extraterrestrial intelligence and Humanity’s inescapable fear of cosmic loneliness

“Late night for Doctor Jerry Ehman

6EQ and it’s bigger than it came in”

SETI vs the Wow! Signal, The Dandy Warhols, 2012

The Wow! Signal referenced here by Millennial Alt Rockers the Dandy Warhols is considered by many to be the strongest contender yet detected for a message beamed to Earth from an extraterrestrial civilization.

Looking through his printouts of data one evening, volunteer analyst Jerry Ehman saw something remarkable – a strong and coherent signal that had all the hallmarks of originating from an artificially engineered source in deep space. Dandies frontman Courtney Taylor Taylor only captures half of the signal in his 2012 lyrics – but in his defence “6EQUJ5” doesn’t scan so well in 4/4 time. What those letters and numbers describe is the changing signal strength in a narrow band of radio wave energy received by the Ohio State University Big Ear radio telescope as it scanned across the night sky on August 15, 1977. Not the random chirps and squawks of cosmic background noise or radio interference that the facility had been recording since it was first turned to the search for alien messages four years earlier, but a clear and substantial signal that systematically rose and fell in intensity over 72 seconds.

Stunned by what he was seeing, Ehman circled the record on his printout and added the notation “Wow!” in red pen to signal his reaction – thereby creating the catchy moniker by which the signal is still known, even in serious scientific discussion. Some commentators have suggested that if he’d written what he’d actually been thinking, we’d now be calling it the ‘Holy shit!’ signal – but I’ve never had the pleasure of meeting Ehman myself, so I can’t judge how excitable he might be.


Scan of a color copy of the original computer printout, complete with Dr Ehman’s excited notation that gives the Wow! Signal its name.


Why the ‘shock and awe’ response to this brief radio signal? Well, put yourself in Ehman’s no-doubt-sensible shoes. Imagine listening to 4 years of static hiss and the occasional random squawk coming from your home sound system, then suddenly having your speakers burst into life with 72 seconds of music at full volume.

Only it wasn’t music. Or at least, we can’t say whether it was music or not. Each of those 6 alphanumeric digits in the record simply reflects the total energy received by the detectors over a 10 second period. We have no way of breaking that down to say whether there was any kind of modulation to the frequency or amplitude of the radio waves over time – something that might represent the complexity of real information – or if this was just a burst of energy (albeit curiously narrowly focused). So in essence, the speakers roared into life, but we’re not sure whether it was Motzart’s Eine kliene Nachtmuzik, Eminem giving out Will the Real Slim Shady Please Stand Up, or Dylan Thomas reciting Under Milkwood. Or indeed, nothing more than intergalactic feedback.

The problem we run up against with applying any kind of deeper interrogation to the Wow! Signal is that the plan of the SETI (Search for Extraterrestrial Intelligence) programme of the time was essentially ‘lets see if we pick up any signals, then think about how we might analyse them and look for information later’. An understandable deficiency, perhaps – after all, if you’ve never seen a candidate signal before and don’t even know whether or not you’ll detect one, it’s probably not your top priority to invest the limited resources that you have in working out the details of what to do with one. Remember, back in the 70s the search for extra terrestrial life was basically thought of – and funded – a bit like Bill Murray and Dan Ackroyd’s parapsychology research lab in the opening act of the original 1984 Ghostbusters movie. There’s a reason why Dr Ehman was a ‘volunteer’ analyst – very few people were actually getting paid to do this stuff as their day job.

In its practical application, unfortunately, this strategy is a bit like going to a bar with the vague idea of picking up girls, but not getting any farther than a plan of ‘if one comes up to talk to us, we’ll work out what to say then’. If a dark eyed vision of feminine beauty then draws herself up on the barstool next to you and starts speaking huskily in French, its too late to start wondering what she’s saying and making plans of how you’ll respond.

At the end of the day though, the Wow! Signal fit every criteria set by the SETI scientists in their “what to expect in a contact with an intelligent extraterrestrial communicator” guide for young spotters. No one-off surge that could be dismissed as an artifact of 20th century electronics, no random scatter of values that could reflect some radical malfunction of the experimental apparatus – the signal progressed in stately fashion from strong, to stronger, to the strongest value ever recorded by Big Ear in its entire 22 years listening to the skies between 1973 and 1995, and then equally steadily decayed away back down to background levels – exactly what would be seen if the stationary telescope was slowly being scanned across a point source in the distant reaches of deep space by the rotation of the Earth. Hackers playing a malicious joke on the Big Ear team can be ruled out because – sit down for a minute to process this one – it was before the development of the internet, at a time when computers were individual monoliths of mute silicon and wire rather than the networked hive minds of the modern day.

Wait – did I say every criteria? Every criterion, that is, except for one crucial element: whoever it was never got back to us. Despite re-scanning the relevant areas of the sky many times (somewhat problematically, because the Big Ear telescope had two detectors, each focused on a slightly different area of the sky, we can’t be sure which one of those the signal came from) both with Big Ear, and with other more sensitive telescopes of the era and in more modern times nothing, not the slightest apparition of a comparable signal, has been seen again. So unless it was the equivalent of an alien civilization being caught whispering “Shhhh – they’re listening – don’t call me on this number” it does become increasingly hard to credit it as an intelligent communication with every passing year.

Whatever the Wow! Signal was though, what this opens up is the interesting question of just why it is that we are so obsessed with the idea of who or what might be out there among the stars.

Humanity has always populated its Universe with creatures of the imagination – fellow travellers that we have imbued with such agency that we have built stories, mythologies, and even religions around them (and in L. Ron Hubbard’s case, all three). In earlier centuries the ‘outside’ domain where these others might wait for us started in the terrestrial sphere – blank spaces on the map filled with dragons, eldritch creatures, and kingdoms of gold – but as exploration has doggedly filled that vacant territory, alien life forms have been pushed ever further from our doorstep, until now the cracks and crevices and distant spaces of our own world are so thoroughly tested that the location of possible ‘others’ has been pushed far from our own neighbourhood, into the realm of different worlds in the far depths of space.

That’s not to say that our deep desire to find a partner has been diminished by this shift in our horizons.

I’m not even talking about fictional imaginings here. Big Ear, after all was just one cog in a substantial and coordinated investigation that has occupied the energies of serious scientific players since the 1960s. Perhaps even more telling of our human obsession, in the modern era, tech billionaire Yuri Milner has recently committed $US 100 million of his own money to a new, large-scale SETI initiative. That’s not just idle curiosity, that’s someone really willing to buy a full-price ticket on the fairground ride – investing 1700 person-years of equivalent resource (at the average Australian salary – proportionally more if you wanted to outsource it to a call centre in India) in the exercise.

What makes Milner and the SETI community think all this investment – time, money, whole careers of activity in some cases from talented and active scientists – is worth it? Do we have any real reason to believe that there are others out there wondering, like us, at the mysteries of the Universe? Or is it just an existential feeling that, as captured in the words of punk pop balladeer Feargal Sharkey in his 1985 single A Good Heart, “Anything is better than being alone”.

Looking to Geological history for insight on this question, life appears to have evolved pretty much as soon as it could have here on our own planet. The oldest sedimentary rocks preserved on Earth contain within them un-mistakable fabrics revealing the presence of bacteria living 3,700 million years ago. Earlier still, even though their body forms have been erased by the tectonic recycling of the crust, isotopic ratios of carbon reveal the telltale signature of biological processing by ancient organisms as far back as we have rocks to measure them in. Over time, these early inhabitants gave rise to multicellular life, vertebrate skeletons, and ultimately, the emergence of all the glorious complexity and variety of our worldly domain. And, of course, our own sentience – and the accompanying blessing (or curse) of wonder at our existence.

As the late paleontologist and prolific essayist Steven Jay Gould was fond of observing though, there is a real and fundamental question as to what would happen if we re-wound the clock and let the experiment start all over again. I’m not talking here about peripheral issues like whether humans would have tails (or in the prosaic words of comedian Rowan Atkinson, we would perhaps have a different shaped gear stick on the Mini Metro). We don’t even know something as fundamental as whether life of any sort would evolve, or the Earth would instead remain a sterile ball of silicate rocks.

As anyone who has ever tried to bleach a shower curtain can tell you, once life gets going it is remarkably persistent and self-moderating. But that initial quickening – the fundamental transition of inorganic chemistry into living organisms…was it a one-off event of miraculous unlikelihood here on Earth? Or is it inevitable if you put carbon, energy and liquid water together? There, surely, is one of the most fundamental questions at the heart of the mystery of the Universe.

Many theoretical concepts have been developed in this space, but empirical testing is rendered problematic by the issue of pathetic statistics: we’ve basically only got a sample set of one to look at – our own home (and history) here on Earth.

This is one of the reasons why Mars assumes such scientific interest. Ever since 1877 when Italian astronomer Giovanni Schiaparelli pointed his telescope at the Red Planet and claimed to see channels built by Martian inhabitants, we Earthlings have been titillated by the possibility of life on Mars. Subsequent probing of our neighbour by observation missions and un-manned landers has clarified that, while Schiaparelli was well wide of the mark, the dry valleys of Mars may indeed have a tale to tell on the evolution of early life.

Why the big deal though? What possible relevance could the presence of life (either now or in the distant past) out there on the frigid surface of Mars have to us here on Earth? The key is that the Red Planet represents only the second place we’ve really had the opportunity to explore, even in passing. If life also developed there, then you go from a single point of data and the corresponding possibility of life originating by near-miraculous happenstance to the (still statistically dubious, obviously) situation of ‘well, every viable place we’ve looked, life developed’ – which would strengthen our expectations that it may also exist elsewhere in the Universe.


Approximate true-color mosaic image of Burns Cliff in Endurance Crater on Mars, captured by the NASA rover Opportunity. Proof that life once existed on the Red Planet’s surface would assume huge significance to thinking about our place in the Universe by demonstrating that the creation of life is replicable, and our own existence is more than the outcome of a cosmic lottery win of unimaginable unlikelihood.


So what about that wider universe then? In the words of Douglas Adams:

“Space is big. Really big. You just won’t believe how vastly hugely mindbogglingly big it is.”

Gaze up into the night sky (as the Big Ear team were probably fond of doing in between their volunteer shifts crunching data back in 1977), and the points of light you see mark out just some of the uncounted billions of stars in the Milky Way galaxy and, in the further distance, billions more galaxies just like our own. We have enough experience now with the careful observations of celestial mechanics necessary to say that most, if not all of these distant stars are probably orbited by their own families of planets. Some proportion of those will presumably sit, like our own comfortable residence, in the so-called ‘Goldilocks zone’ around their respective sun – not too hot, not too cold – where liquid water is stable. If we assume that some proportion of those potential alien domiciles see life kick-started as it was here on Earth (however that happens), some proportion of those biological incubators see the emergence of multicellular life, some proportion of these see development of some form of sentience…the powerful and attractive logic of extraterrestrial civilisations out there – alien eyes staring up at alien suns – becomes obvious.

Which brings us to the Fermi Paradox: when you put it like this, logical argument would seem to suggest that many technologically advanced civilizations might exist in the universe, but this belief seems inconsistent with our lack of observational evidence to support it. Or, as put more pithily by the great Nobel Prize winning Physicist Enrico Fermi himself – “Where is everybody?”

For all our uncounted generations of staring heavenwards and looking for a sign, all the millions of dollars invested in serious SETI research over the past 50 years, what have we got to show for it? No invitations to intergalactic councils. No imperious threats of our imminent destruction. Not even a poignant “I am Ozymandias, King of Kings, look on my works ye mighty and despair” from some long-vanished civilization.

For a point of comparison, the new enhanced Laser Interferometer Gravitational-Wave Observatory in the United States picked up two black holes colliding pretty much the first time it was turned on for a test run earlier this year, and detected another collision just last month. Going by those statistics, collisions between black holes – astronomical features so vanishingly rare in their own right that until recently they were nothing more than abstract Cosmological theory and the fodder for science fiction imaginings – appear to be vastly more numerous than advanced alien civilisations out there.

Actually, speaking of science fiction, for my money it’s probably 20th century writer and futurist Isaac Asimov whose musings on this point best capture the philosophical implications of the search for extra-terrestrial life:

“Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.”

So to turn full circle back to the curious event that kicked off this discussion in the first place – what was the Wow! Signal? Was this Jor-El beaming out the sum total of Krypton’s knowledge as his world collapsed, in the hope that our distant civilization would receive it and carry on his work? And we’re caught here on Earth saying “hang on, I’ll just get my pencil…oh, they’ve gone.” Or possibly nothing more than some previously unknown natural radiowave phenomenon reaching us from deep space – still a mystery to be explained, to be sure, but lacking the radical overtones of extraterrestrial contact.

Well, perhaps…but then again – I’m sure I’m not the first person to notice this, but the Wow! Signal was received the day before Elvis Presley ‘died’. Coincidence? Or the King being called home?

Of Cats and Cashflow: Human sentimentality and the flaw in economic rationalism

Last Christmas, I paid $5000 for a cat.


For a cat.

“Cat” here, in case you should be wondering, is not the title of an avant garde piece of sculpture by some breaking new artist, or a colloquial reference to a rare wine or other exclusive gift for a loved one. Nor indeed, anything special in the feline department.

Just an ordinary cat that my 9 year old daughter had saved her pocket money to rescue from the Animal Shelter. Yes, okay, it’s accepted family lore that he is actually a pedigree animal who somehow found himself down on his luck on kitty skid row – but I can accept there may be a degree of parental self-delusion in that particular idea.

Whatever his back story though, as the warm summer evenings of 2013 began to lengthen, heralding the winding down of business and arrival of the holiday season, all thoughts of casual beachside barbecues and Christmas relaxation were rudely dashed for me one Saturday morning as young Pedro – having manfully picked a fight with a passing car – dragged his sorry frame into the house and collapsed theatrically in the middle of the living room floor.

After a quick cat scan at the local veterinary hospital (no, not a moment of levity playing on my feline friend’s biological order there – a real actual honest-to-goodness “cash up front please sir” CAT scan cat scan) showed up the incontrovertible evidence of a clean and comprehensive break right through the young street fighter’s pelvis, the therapeutic choices came to a quick fork in the road. One path led to major surgery, emptying of savings accounts (“kids – hands up who’s going to University. Not so fast there you two”), and having a half-shaved grumpy convalescing cat locked in a cage in our cosy house through the warmest weeks of summer. The other, to a quiet, calm, fully funded holiday season. Even a couple of weeks of really nice vacation. As well as the sticky point of explaining to my daughter why her precious kitty wouldn’t be joining us for Christmas dinner.

The path we chose (and I say “we” here entirely in the blame-shifting and shared responsibility sense – my wife’s version of this story may differ on the precise extent to which each of us couldn’t stomach the tough decision making) probably tells you everything you need to know about why I’m never likely to make the annual list of Australia’s 10 hardest hearts. And why you shouldn’t take my advice on anything to do with finance.

The point is, this doesn’t qualify as an investment decision. It’s not like I had some brilliant plan to parlay this $5000 outlay into a major stream of retirement income. Even if the cat in question is possessed of the kind of dashing good looks that could make him a major star in pet food commercials…if he could at some point stop trying to take a chunk out of any hand with the temerity to pat him without explicit permission.

No, it just turns out that little tiny titanium screws are really expensive. If you want them put somewhere useful by a veterinary surgeon, anyway.

The much pampered and perhaps overly tolerated Pedro - a few lives down from his initial quota of 9 perhaps, but still going strong as an extended metaphor for social relativism. And definitely not just a shameless attempt to elevate my viewing stats through use of a cute cat picture.

The much pampered and perhaps overly tolerated Pedro – a few lives down from his initial quota of 9, but still going strong as an extended metaphor for social relativism. And definitely not just a shameless attempt to elevate my viewing stats through use of a cute cat picture.

And there, laid bare for the world to see, lies the fundamental flaw with economic rationalism. People are not reliably rational actors on the world stage – we all bring our personal values, idiosyncrasies and biases to economic decision making.

For those of you who might not be fully familiar with the concept, economic rationalism (market liberalism, for readers from outside Australia) is the dogmatic view that markets and money can always do everything better than governments, bureaucracies and the law.

In the more prosaic words of Michael Pusey – Professor of Sociology at the University of New South Wales: “Forget about history and forget about national identity, culture and ‘society’…Don’t even think about public policy, national goals or nation-building. It’s all futile. Just get out of the way and let prices and market forces deliver their own economically rational solution.”

This philosophy underpinned a sharp step to the right across much of the Western political sphere in the 1980s and 90s – think the Hawke-Keating-Howard years in Australia, Thatcherism and its correlatives in Europe – and has more recently been used as the basis for a strict balance sheet approach to management in many areas of wider society – education, housing, the arts, even environmental policy.

This deference to accounting undeniably has a certain elegance to it – a simple coherent narrative that can easily be painted on a placard, or broadcast in a 6 second sound bite. Like Creationism re-packaged for a political audience though (and with many of the same elements of true belief and ideological fervor), the sneaky trick here is that while this is dressed up as analytical economics, really it is all about political philosophy – the ideology of unfettered personal freedom. Don’t get me wrong – it is entirely proper for economic rationalists (or anybody else) to allow value judgments about freedom to define their policy prescriptions. It is improper and, more importantly, incorrect, however, to claim that these ideas flow simply from the laws of economics, and possess some sort of inescapable mathematical truth.

The beauty of mathematics, of course – the reason political and social movements have long sought to co-opt it to their crusades – is that it gives defined, absolute solutions. Put your numbers into an equation, and you get an answer at the end. To as many significant figures as you like. This allows us to do amazing things – like build giant flying machines from aluminium and carbon fibre that can carry hundreds of passengers around the world in a matter of hours. Or land a spacecraft on the surface of Comet 67P/Churyumov-Gerasimenko hurtling through space 510 million kilometres from Earth.

Real world problems though – especially anything touched by the inordinate complexity of human social psychology – commonly fail to lend themselves to mathematical solution. The real world simply has too many possibilities and undefined variables – such that equations have no solid foundations they can be anchored to.

To make problems tractable – to allow mathematics to give us that pure, crystalline answer – we usually make certain assumptions to tie down the open ended possibilities and give us a solvable domain to work within. The danger here though is of ending up with what the great 20th Century physicist and public champion of science Richard Feynman used to call a spherical cow argument (readers of my earlier posting on University fees “More Pennies for Your Thoughts” will have seen a longer explanation of this concept) – an assumption that, while making your equation solvable, also removes any meaningful relationship to the physical system it purports to represent – and when that happens the clean precision of a mathematical solution can be misleading. Or worse.

The NASA engineers plotting the journey of the Mars Climate Orbiter to the Red Planet in 1999 produced incredibly precise solutions. They also assumed the output of one of the key pieces of navigation software on the Orbiter was in metric Newtons of force…when it was actually in pounds of thrust. Oops. This rendered their solutions elegant, precise…and dead wrong, with the $USD 125 million satellite coming in too close to the planet and breaking up in the Martian atmosphere.

Perhaps more than such elementary cases of error, however, the important thing to grasp in a social context is that you can use framing assumptions to distort the result in any direction you might desire. Want to argue against the opening of a new coal mine? Include some cost assumptions about externalities like atmospheric pollution, environmental risk, and increased traffic to show the economics don’t stack up. Or as I showed in an earlier blog, want to argue in favour of higher University fees? Make some helpful assumptions about the financial advantage accruing to a graduate while discounting the societal benefits and increased tax revenue from a more educated population.

Even in the best of circumstances though – if we assume (at the risk of vanishing into the never ending hall of mirrors that is self-referential logic) all our assumptions are correct and appropriate – the critical point to remember is that economics cannot tell you what is the right choice. Morality and values do not drop out of financial equations like wisdom paying out from a philosophical poker machine. Any investment decision comes down to a balance of short term sacrifice against long term gain. Instead of spending your money on something now, you invest it in the expectation of gaining greater reward at some future point.

When it comes to quantifying outcomes – basic economics – that can be a pretty straightforward calculation. “If I have $1000 now, would it be better to stuff it in my mattress or invest it in government bonds for 10 years”. Okay, there are still some assumptions to make about yields and the potential of unexpected events like your significant other throwing your mattress in a skip while you’re at work. Or a plunge in the commodity price on which a government had based all its economic projections, driving it to default on its debts (Hmmmmm…so how is the iron ore market going, by the way?)

By and large though, you can produce a pretty robust solution to that kind of question and say which one is likely to give you the higher return over a 10 year period.

Defining what the sensible decision is based on those results though – now there’s the challenge – with a crack arising in the logic around defining how great a long-term premium is required to make the short term sacrifice worthwhile.

Let’s say that Mike believes that the pleasure he derives from eating a custard slice is an appropriate trade for the 30 seconds it might shave off his life (or the hour in the gym it will take to work off all that delicious vanilla flavoured excess), whereas Susan doesn’t think the momentary pleasure of the creamy mouthful is worth the sacrifice. Who is right? Both are, of course. It’s a question of values and opinion, it has no absolute solution – no single true answer that trumps or invalidates all others.

Orthodox economics is very clear that policy recommendations must rest on both economic analysis AND a set of values. There is no objective adamantine economic ‘truth’ – the social implications of financial modeling depend on your personal beliefs and values.

Even Milton Friedman – often held up as the philosophical father of Economic Rationalism – understood this qualification, stating:

“As Liberals, we take freedom of the individual, or perhaps the family, as our ultimate goal in judging social arrangements.”

No special pleadings or claims of incontrovertible quantitative support there – Friedman is perfectly comfortable acknowledging that his social policy ideas (a fountainhead that fed both Reagan and Thatcher in their glory days of social engineering and reform, let us remember) are based on an ideology. And that’s fine. On that basis, you can assess and debate his arguments, and decide for yourself whether that’s the model you would like to see underpinning the society you live in. Friedman, unlike the hardline Economic Rationalists who have followed in his intellectual wake, allows that alternative social models may be equally valid if you don’t happen to share his values.

Like, for example, valuing a deeply ungrateful cat (and the happiness of a small child) more than a new sofa or a week in Paris.

And hey – at the end of the day, even if we were all perfectly rational actors making our life decisions on the basis of pure logic and mathematics, that might not actually be the lasting social panacea the Economic Rationalists hope for. You’ve seen what happens to the planet Vulcan in J. J. Abrams’ 2009 Star Trek re-boot, right?

Sticky Fingers: Changing Old Noise to New Data in the Course of Scientific Discovery

“I suppose you won’t be able to find one of your famous Clues on the thing?”

“Shouldn’t think so, sir. Not with all these fingerprints on it.”

Terry Pratchett, “Feet of Clay”

Captured in Pratchett’s satirical writing here is a key concept underpinning the advancement of science: In recognising the deficiencies of our understanding, we identify pathways to more fundamental, deeper insight.

If you might indulge me in illustrating this concept: The science of geochronology is only a little over a hundred years old. The genesis of this field – the direct measurement of the age of Earth materials in the millions and even billions of years, putting a timescale to the grinding wheels of geological process – is probably traceable most directly to the New Zealander (albeit that we should add the prefix ‘Colonial’ to that label, given he undertook his post-graduate education and scientific career at Cambridge University in Britain) Ernest Rutherford – one of the great figures of 19th and early 20th century physics. Scientists don’t often ascend to the pantheon of cultural heroes, so the fact that Rutherford’s distinguished portrait graces the $50 note of his country of birth is probably as effective a mark as any of the degree to which he bestrode the world stage, and the respect in which he is still held.

With his finger on the scientific pulse of the Edwardian age – and in particular the atomic theory at the heart of his own cutting-edge research – Rutherford was quick to appreciate the significance of the new phenomenon of radioactivity discovered by his contemporaries Marie and Pierre Curie. In the words of the great man himself:

“The helium observed in the radioactive minerals is almost certainly due to its production from the radium and other radioactive substances contained therein. If the rate of production of helium from known weights of the different radioelements were experimentally known, it should thus be possible to determine the interval required for the production of the amount of helium observed in radioactive minerals, or, in other words, to determine the age of the mineral.”

Ernest Rutherford – Silliman Lectures at Yale, 1905

With those words, a scientific revolution began.

Rutherford quickly set to work encouraging collaborators in the fields of chemistry, physics, and geology to put that principle into practice, but it didn’t take long for the community to recognise that his original elegant concept wasn’t going to be the simple path to greater knowledge that they had hoped for. The problem was that helium – the simple, easily extracted product of radioactive alpha decay – wasn’t fully retained in the mineral structures they were testing. In the words of John Strutt, one of the key figures in this early research:

“[helium ages provide only] minimum values, because helium leaks out from the mineral, to what extent it is impossible to say.”

R. J. Strutt (1910), Proceedings of the Royal Society of London

Some process – unknown at the time – was allowing the helium to escape from the crystals. Like a water clock with a leak in it then, there was no true fundamental way to calculate age from the system.

The key to our story here is that the contemporary paradigm to which these scientists were working was that the only age that mattered was the time at which a sample crystallised – nothing else entered their world view. When helium dating returned values that were clearly far too young and inconsistent to reflect such formation ages, the method was consequently abandoned, with the scientific community pursuing other isotopic systems – notably the pairing of uranium isotopes with their ultimate stable decay product of lead – as the pathway to temporal understanding of Earth evolution.

90 years later at the turn of the 21st century though, helium dating was back on the scene and a hot property (quite literally, as it turns out – but more of that later) in the field of geochronology – and it remains so right up to the present day. Why? Have we just forgotten the lessons of the past?

To understand the answer to that question, you need to appreciate that an isotopic ‘age’ is fundamentally just a ratio of chemical species – namely the abundance of a radioactive parent isotope – the ticking clock of the system – and the product of its decay within your sample. Ultimately, this is just a number – nothing more or less…unless you have a physical event you can relate that number to. If I toss you a rock and say “this rock is 7,000 years old” – what does that mean? Is it 7,000 years since the rock crystallised? 7,000 years since it was knocked from a large boulder upstream? That it has spent 7,000 years tumbling back and forth in the surf? 7,000 years lying on the beach? All these ‘ages’ might have meaning – telling us something interesting about the history of this particular sample – but unless you know which one I mean, the manifold possibilities obscure the potential insight.

Nice looking piece of rock - so how old is it? And how would we tell?

Nice looking piece of rock – so how old is it? And how would we tell?

To address this confusion from the perspective of helium, let’s drill down from the scale of rocks and hammers to the sub-microscopic world of a crystal lattice. The comforting solidity and discrete character of the everyday is replaced by a dynamic constellation of atomic structures held in place by overlapping and interfering clouds of electrons and opposing forces – a seething maelstrom of movement and change. As those particles spin and vibrate, the force balances governing their interactions rise and fall, bonds parting and re-forming in the blink of a conceptual eye as their stability waxes and wanes. Take a moment to watch this video clip from Dr Erik Laegsgaard at Aarhus University.

Scanning Tunneling Microscope imagery of atomic-scale diffusion in titanium dioxide, created by Dr Erik Laegsgaard, Aarhus University. Recorded at 300 degrees Kelvin, and at 8.6 seconds/frame.

Each of those glowing orange orbs is actually an atom of oxygen resolved by advanced scanning tunnelling microscopy of a sample of titanium dioxide. To my thinking, this movie is mind blowing – this is not a cartoon, or a fancy computer model – this is an actual resolved record of real individual atoms, in solid material, at room temperature. Reflect for a moment on just how we see those atoms behave as the movie advances through time. Rather than locked in place like mosaic tiles set in mortar, they skitter back and forth – momentarily held in the embrace of one bond, but then twisting away across the crystalline dance floor to some new partnership. The movement is random and unpredictable – particles as likely to jump one way as any other.

This atomic diffusion is what was responsible for Strutt’s anomalous ‘leakage’. Although the movements are individually random, if you’re building up an increased concentration of something (as with the helium produced by alpha decay in the example of our geochronometer), then you’re statistically more likely to have those random movements going out of the radioactive crystal structure than into it. It follows that this diffusion will prevent the build up of your daughter product (helium), keeping the isotopic age stuck stubbornly at zero.

So how then do we stop diffusion happening and allow our ticking clocks to record time? How do we set the geological stopwatch running? The simple answer is temperature – you cool things down. The rate at which diffusion occurs is proportional to temperature raised to an exponential power. In essence, this means that even a small change in temperature leads to a very large change in diffusivity, and the transition from rapid diffusion – so rapid that all the daughter product produced by radioactive decay is lost – to negligible diffusion where all that daughter product is retained – occurs across a very narrow temperature range.

Rather than the aberrant or spoiled data Strutt took them to be then, helium ages, once we understand this process and calibrate its thermal sensitivity, become sensitive records of the temperature change associated with dynamic geological history.

How does this help us?

When Gil Grissom finds a gun at the scene of a murder in CSI (yes, I know Grissom left the show after series 9, but I always thought he had excellent style as an on-screen scientist, and geologically speaking, his tenure is pretty much still within error of the present), his first thought isn’t “I must find out how old this gun is” – no – there are far more dynamic aspects of the weapon’s history he would like to see resolved. When was it bought? How long ago was it fired? Who pulled the trigger?

Similarly, if we focus purely on the crystallisation age of our samples, as Strutt, Rutherford, and their contemporaries were, there are many potential insights we will miss.

When were our samples last thrust beneath the crushing weight of an uplifting mountain range? When did they last feel the rush of superheated steam carrying rich mineral endowment through subterranean fluid conduits, or the frictional warmth induced by an active fault boundary radiating through the crust? When did erosion wear away its weighty overburden to exhume our rock from the hot interior of the Earth? With the thermal ages provided by helium dating and its correlatives, these dynamic episodes come within our grasp.

What was simply noise becomes, when we understand and can translate its origin, a sensitive new record of dynamic geological processes.

Unlike Pratchett’s protagonists, our FBI database is ready, and the fingerprints of geological systems are waiting to reveal themselves to our careful detective work.

French String – Mathematics, Linguistics, and the Nature of Reality

“Daddy,” my eldest daughter asked me, some years ago now (at a time when Europe was but a short train ride away and a welcome escape from the grey winters of Surrey), “What’s the Spanish word for thank you?”

“Gracias.” I replied, pleased by her inquisitiveness “And denada means you’re welcome.”

Warming to the conversation, she went on “Oh. And what’s thank you in French?”


“And what do they say for you’re welcome?”

I paused for a moment (but only, it must be said, a moment) reflecting on the fact that I had no idea how to express that concept – my ability with the French language extending little further than ordering coffee and croissants for breakfast – before telling her, with all my fatherly sincerity “The French have no phrase for that.”

Now yes, I admit it was a cheap knee-bend to Francophone stereotypes, and a ‘Dad joke’ to cover my linguistic ignorance…and it was probably inappropriate for me to let an impressionable child go on believing this for as long as I subsequently did.

But it does introduce an interesting and important concept – our ability to describe something has no bearing on its reality. Even if my statement were true and the French had, through some curious artifact of linguistic heritage, failed to develop a phrase capable of expressing gratitude, it would not change the fact that such feelings could – and do – exist. Language describes reality. It does not – outside of the most extreme hardline views of social constructivism – define it.

Mathematics too is essentially a language – a language, moreover, that we can use to describe the physical reality of the universe. Most of the time. As with the example of spoken language above though, the critical caveat is that however well mathematics describes physical behaviour, again, it does not define it.

Sir Phillip Bin, the fictional hero of Mark Evans’ radio comedy ‘Bleak Expectations’, muses wistfully on the days before Sir Isaac Newton ‘invented’ gravity, when people falling from great height would ‘simply drift gently and harmlessly to the ground’.

Such satirical diversions aside, Newtonian mechanics works pretty well in describing the interactions of macroscopic objects under the conditions of our everyday experience. But gravitational attraction between two bodies doesn’t fall off in proportion to the square of the distance between them because that’s the way the equation is written – rather, the equation seeks to empirically describe the behaviour that occurs.

As Einstein recognised in his theories of general and special relativity, under certain circumstances – far removed from the world of everyday experience – objects behave in ways that are incompatible with Newtonian physics. In formulating expressions to account for this relativistic behaviour, Einstein did not change the nature of the universe – he simply gave us a new form of language by which to describe the poetry of our existence.

Similarly, the remarkable duality of electrons – whereby they can be shown through physical experiment to possess the characteristics of both a continuous wave function and a discrete physical particle – is only a paradox in the context of the ways in which we have come to describe these sub-atomic features. Fundamentally, the electron is what it is, and if theories are unable to fully account for its behaviour, it is a reflection of the inadequacy of our mathematical approximations for reality, not proof of some cosmic trick set up to titillate a Vegas audience on the quantum scale.

Perhaps the most interesting example of this concept in action, however, is the search for an ultimate physical ‘theory of everything’. The properties of electromagnetism, strong nuclear and weak nuclear attraction, and gravity – the fundamental forces that define and control interactions of matter and energy throughout the universe – converge at high energy, and it is theorized that all four derive from a common underlying property. But just what this is remains a point of hard debate, as none of the individual equations that are so successful in describing the behaviour of each of these forces on the macroscopic level of the everyday can adequately cope with the conditions of this theoretical point of convergence.

This does not mean that there are somehow four separate overlapping layers making up the Universe that don’t quite fit together perfectly where they join, like some kind of badly put together set of existential DIY shelves. Rather, the theory runs that there is one reality, where all aspects of the physical behaviour that we observe in the universe must somehow derive from the fundamental character of matter and energy. The failure lies in the mathematical language in our possession – it’s not just that it’s tricky to calculate the results, standard mathematics is literally unable to describe reality under those conditions.

The ‘theory of everything’ that can account for the emergence and existence of these separate forces is one of the great challenges at the business end of modern physics where the big kids of theory get serious. Tackling this problem however requires not just a dab hand with a slide rule, but the creation – literally – of entirely new forms of mathematics, incorporating additional physical fields and interactions, and even extra dimensions of space.

For the record, I should confess that I’m not one of those big kids – a real physicist would have stolen my mathematical lunch money and sent me crying for home long before we even got to string theory – which I understand is regarded as one of the more accessible (and promising) of these approaches. As secret shames go, I can appreciate that this is not exactly stupendous, but I’ve been happily married for 16 years and don’t get out to as many wild parties as I used to.

The point is, I’m fine with that. I don’t need to understand the higher order branches of mathematics – the high linguistics of the Physicist’s hymnal – to appreciate the reality and significance of what they are trying to achieve in understanding the nature of reality. I wish them well, and look forward to the day that Google produces a Mathematics-English translator so I can appreciate the beauty of their work.

I’m sure even the French would be grateful for that.