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on the explosion of battery research – part two, a bitsy presentation

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This EV battery managed to run for 1200 kilometres on a single charge at an average of around 51 mph

Ok, in order to make myself fractionally knowledgable about this sort of stuff I find myself watching videos made by motor-mouthed super-geeks who regularly do blokes-and-sheds experiments with wires and circuits and volt-makers and resistors and things that go spark in the night, and I feel I’m taking a peek at an alternative universe that I’m not sure whether to wish I was born into, but I’ll try anyway to report on it all without sounding too swamped or stupefied by the detail.

However, before I go on, I must say that, since my interest in this stuff stems ultimately from my interest in developing cleaner as well as more efficient energy, and replacing fossil fuel as a principal energy source, I want to voice my suspicions about the Australian federal government’s attitude towards clean and renewable energy. This morning I heard Scott Morrison, our nation’s Treasurer, repeating the same deliberately misleading comments made recently by Josh Frydenberg (the nation’s energy minister, for Christ’s sake) about the Tesla battery, which is designed to provide back-up power as part of a six-point SA government plan which the feds are well aware of but are unwilling to say anything positive about – or anything at all. Morrison, Frydenberg and that other trail-blazing intellectual, Barnaby Joyce, our Deputy Prime Minister, have all been totally derisory of the planned battery, and their pointlessly negative comments have thrown the spotlight on something I’ve not sufficiently noticed before. This government, since the election of just over a year ago, has not had anything positive to say about clean energy. In fact it has never said anything at all on the subject, by deliberate policy I suspect. We know that our PM isn’t as stupid on clean energy as his ministers, but he’s obviously constrained by his conservative colleagues. It’s as if, like those mythical ostriches, they’re hoping the whole world of renewables will go away if they pay no attention to it.

Anyway, rather than be demoralised by these unfortunates, let’s explore the world of solutions.

As a tribute to those can-do, DIY geeky types I need to share a great video which proves you can run an electric vehicle on a single charge for well over 1000ks – theirs made it to 1200ks – 748 miles in that dear old US currency – averaging around 51 mph. It’s well worth a watch, though with all the interest there are no doubt other claimants to the record distance for a single charge. Anyway, you can’t help but admire these guys. Tesla, as the video shows, are still trying to make it to 1000ks, but that’s on a regular, commercial basis of course.

In this video, basically an interview with battery researcher and materials scientist Professor Peter Bruce at Oxford University, the subject was batteries as storage systems. These are the batteries you find in your smart phones and other devices, and in electric vehicles (EVs). They’ll also be important in the renewable energy future, for grid storage. You can pump electricity into these batteries and, through a chemical process that I’m still trying to get my head around, you can store it for later use. As Prof Bruce points out, the lithium-ion battery revolutionised the field by more or less doubling the energy density of batteries and making much recent portable electronics technology possible. This energy density feature is key – the Li-ion batteries can store more energy per unit mass and volume. Of course energy density isn’t the only variable they’re working on. Speed of charge, length of time (and/or amount of activity) between charging, number of discharge-recharge cycles per battery, safety and cost are all vitally important, but when we look at EVs and grid storage you’re looking at much larger scale batteries that can’t be simply upgraded or replaced every few months. So Bruce sees this as an advantage, in that recycling and re-using will be more of a feature of the new electrified age. Also, as very much a  scientist, Bruce is interested in how the rather sudden focus on battery storage reveals gaps in our knowledge which we didn’t really know we had – and this is how knowledge often progresses, when we find we have an urgent problem to solve and we need to look at the basics, the underlying mechanisms. For example, the key to Li-ion batteries is the lithium compound used, and whether you can get more lithium ions out of particular compounds, and/or get them to move more quickly between the electrodes to discharge and recharge the battery. This requires analysis and understanding at the fundamental, atomistic level. Also, current Li-ion batteries for portable devices generally use cobalt in the compound, which is too expensive for large-scale batteries. Iron, manganese and silicates are being looked at as cheaper alternatives. This is all new research – and he makes no mention of the work done by Goodenough, Braga et al.

In any case it’s fascinating how new problems lead to new solutions. The two most touted and developed forms of renewable energy – solar and wind – both have this major problem of intermittence. In the meantime, battery storage, for portable devices and EVs, has become a big thing, and now new developments are heating up the materials science field in an electrifying way, which will in turn hot up the EV and clean energy markets.

The video ended by neatly connecting with the geeky DIY video in showing how dumped, abandoned laptop batteries and other batteries had plenty of capacity left in them – more than 60% in many cases, which is more than useful for energy storage, so they were being harvested by PhD students for use in small-scale energy storage systems for developing countries. Great for LED lighting, which requires little power. The students were using an algorithm to get each battery in the system to discharge at different rates (since they all had different capacities or charge left in them) so they could get maximum capacity out of the system as a whole. I think I actually understood that!

Okay – something very exciting! The video mentioned above is the first I’ve seen of a British series called ‘Fully Charged’, all about batteries, EVs and renewable energy. I plan to watch the series for my education and for the thrill of it all. But imagine my surprise when I started watching this one, still part of the series, made here in Adelaide! I won’t go into the content of that video, which was about flow batteries which can store solar energy rather than transferring it to the grid. I need to bone up more on that technology before commenting, and it’s probably a bit pricey for the likes of me anyway. What was immediately interesting to me was how quickly he (Robert Llewellyn, the narrator/interviewer) cottoned on to our federal government’s extreme negativity regarding renewables. Glad to have that back-up! I note too, by the way, that Australia has no direct incentives to buy EVs, of which there are few in the country – again all due to our troglodyte government. It’s frankly embarrassing.

So, there’s so much happening with battery technology and its applications that I might need to take some time off to absorb all the videos and docos and blogs and podcasts and development plans and government directives and projects and whatnot that are coming out all the time from the usual and some quite unusual places, not to mention our own local South Australian activities and the naysayers buzzing around them. Then again I may be moved to charge forward and report on some half-digested new development or announcement tomorrow, who knows….

References

They’re all in the links above, and I highly recommend the British ‘Fully Charged’ videos produced by Robert Llewellyn and Johnny Smith, and the USA ‘jehugarcia’ videos, which, like the Brit ones but in a different way, are a lot of fun as well as educational.

 

Written by stewart henderson

August 1, 2017 at 9:26 pm

on the explosion of battery research – part one, some basic electrical concepts, and something about solid state batteries…

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just another type of battery technology not mentioned in this post

Okay I was going to write about gas prices in my next post but I’ve been side-tracked by the subject of batteries. Truth to tell, I’ve become mildly addicted to battery videos. So much seems to be happening in this field that it’s definitely affecting my neurotransmission.

Last post, I gave a brief overview of how lithium ion batteries work in general, and I made mention of the variety of materials used. What I’ve been learning over the past few days is that there’s an explosion of research into these materials as teams around the world compete to develop the next generation of batteries, sometimes called super-batteries just for added exhilaration. The key factors in the hunt for improvements are energy density (more energy for less volume), safety and cost.

To take an example, in this video describing one company’s production of lithium-ion batteries for electric and hybrid vehicles, four elements are mentioned – lithium, for the anode, a metallic oxide for the cathode, a dry solid polymer electrolyte and a metallic current collector. This is confusing. In other videos the current collectors are made from two different metals but there’s no mention of this here. Also in other videos, such as this one, the anode is made from layered graphite and the cathode is made from a lithium-based metallic oxide. More importantly, I was shocked to hear of the electrolyte material as I thought that solid electrolytes were still at the experimental stage. I’m on a steep and jagged learning curve. Fact is, I’ve had a mental block about electricity since high school science classes, and when I watch geeky home-made videos talking of volts, amps and watts I have no trouble thinking of Alessandro Volta, James Watt and André-Marie Ampère, but I have no idea of what these units actually measure. So I’m going to begin by explaining some basic concepts for my own sake.

Amps

Metals are different from other materials in that electrons, those negatively-charged sub-atomic particles that buzz around the nucleus, are able to move between atoms. The best metals in this regard, such as copper, are described as conductors. However, like-charged electrons repel each other so if you apply a force which pushes electrons in a particular direction, they will displace other electrons, creating a near-lightspeed flow which we call an electrical current. An amp is simply a measure of electron flow in a current, 1 ampere being 6.24 x 10¹8 (that’s the power of eighteen) per second. Two amps is twice that, and so on. This useful video provides info on a spectrum of currents, from the tiny ones in our mobile phone antennae to the very powerful ones in bolts of lightning. We use batteries to create this above-mentioned force. Connecting a battery to, say, a copper wire attached to a light bulb causes the current to flow to the bulb – a transfer of energy. Inserting a switch cuts off and reconnects the circuit. Fuses work in a similar way. Fuses are rated at a particular ampage, and if the current is too high, the fuse will melt, breaking the circuit. The battery’s negative electrode, or anode, drives the current, repelling electrons and creating a cascade effect through the wire, though I’m still not sure how that happens (perhaps I’ll find out when I look at voltage or something).

Volts

So, yes, volts are what push electrons around in an electric current. So a voltage source, such as a battery or an adjustable power supply, as in this video, produces a measurable force which applied to a conductor creates a current measurable in amps. The video also points out that voltage can be used as a signal, representing data – a whole other realm of technology. So to understand how voltage does what it does, we need to know what it is. It’s the product of a chemical reaction inside the battery, and it’s defined technically as a difference in electrical potential energy, per unit of charge, between two points. Potential energy is defined as ‘the potential to do work’, and that’s what a battery has. Energy – the ability to do work – is a scientific concept, which we measure in joules. A battery has electrical potential energy, as result of the chemical reactions going on inside it (or the potential chemical reactions? I’m not sure). A unit of charge is called a coulomb. One amp of current is equal to one coulomb of charge flowing per second. This is where it starts to get like electrickery for me, so I’ll quote directly from the video:

When we talk about electrical potential energy per unit of charge, we mean that a certain number of joules of energy are being transferred for every unit of charge that flows.

So apparently, with a 1.5 volt battery (and I note that’s your standard AA and AAA batteries), for every coulomb of charge that flows, 1.5 joules of energy are transferred. That is, 1.5 joules of chemical energy are being converted to electrical potential energy (I’m writing this but I don’t really get it). This is called ‘voltage’. So for every coulomb’s worth of electrons flowing, 1.5 joules of energy are produced and carried to the light bulb (or whatever), in that case producing light and heat. So the key is, one volt equals one joule per coulomb, four volts equals 4 joules per coulomb… Now, it’s a multiplication thing. In the adjustable power supply shown in the video, one volt (or joule per coulomb) produced 1.8 amps of current (1.8 coulombs per second). For every coulomb, a joule of energy is transferred, so in this case 1 x 1.8 joules of energy are being transferred every second. If the voltage is pushed up to two (2 joules per coulomb), it produces around 2 amps of current, so that’s 2 x 2 joules per second. Get it? So a 1.5 volt battery indicates that there’s a difference in electrical potential energy of 1.5 volts between the negative and positive terminals of the battery.

Watts

A watt is a unit of power, and it’s measured in joules per second. One watt equals one joule per second. So in the previous example, if 2 volts of pressure creates 2 amps of current, the result is that four watts of power are produced (voltage x current = power). So to produce a certain quantity of power, you can vary the voltage and the current, as long as the multiplied result is the same. For example, highly efficient LED lighting can draw more power from less voltage, and produces more light per watt (incandescent bulbs waste more energy in heat).

Ohms and Ohm’s law

The flow of electrons, the current, through a wire, may sometimes be too much to power a device safely, so we need a way to control the flow. We use resistors for this. In fact everything, including highly conductive copper, has resistance. The atoms in the copper vibrate slightly, hindering the flow and producing heat. Metals just happen to have less resistance than other materials. Resistance is measured in ohms (Ω). Less than one Ω would be a very low resistance. A mega-ohm (1 million Ω) would mean a very poor conductor. Using resistors with particular resistance values allows you to control the current flow. The mathematical relations between resistance, voltage and current are expressed in Ohm’s law, V = I x R, or R = V/I, or I = V/R (I being the current in amps). Thus, if you have a voltage (V) of 10, and you want to limit the current (I) to 10 milli-amps (10mA, or .01A), you would require a value for R of 1,000Ω. You can, of course, buy resistors of various values if you want to experiment with electrical circuitry, or for other reasons.

That’s enough about electricity in general for now, though I intend to continue to educate myself little by little on this vital subject. Let’s return now to the lithium-ion battery, which has so revolutionised modern technology. Its co-inventor, John Goodenough, in his nineties, has led a team which has apparently produced a new battery that is a great improvement on ole dendrite-ridden lithium-ion shite. These dendrites appear when the Li-ion batteries are charged too quickly. They’re strandy things that make their way through the liquid electrolyte and can cause a short-circuit. Goodenough has been working with Helena Braga, who has developed a solid glass electrolyte which has eliminated the dendrite problem. Further, they’ve replaced or at least modified the lithium metal oxide and the porous carbon electrodes with readily available sodium, and apparently they’re using much the same material for the cathode as the anode, which doesn’t make sense to many experts. Yet apparently it works, due to the use of glass, and only needs to be scaled up by industry, according to Braga. It promises to be cheaper, safer, faster-charging, more temperature-resistant and more energy dense than anything that has gone before. We’ll have to wait a while, though, to see what peer reviewers think, and how industry responds.

Now, I’ve just heard something about super-capacitors, which I suppose I’ll have to follow up on. And I’m betting there’re more surprises lurking in labs around the world…

 

 

Written by stewart henderson

July 29, 2017 at 4:00 pm

reveries of a solitary wa*ker: wa*k 3

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my new Dino-lite Basic, and some coriander roots, under low magnification

my new Dino-lite Basic, and some coriander roots, under low magnification

coriander roots

Having finished reading the big Darwin book I’m letting the influence of his character and world percolate through me, for example on my way home from work the other day, walking by the city river, I got the idea of taking pics of the bird species hanging by the riverside with my mobile phone – murray magpie, mallard, eurasian coot, black swan, masked lapwing, Australian pelican, Australian magpie, dusky moorhen, Australian white ibis and little pied cormorant. It really brightened my day, though the photos were pretty crappy, but I looked up the species when I got home (this is where the internet really comes into its own) and learned so much about habitats, male-female differences (the male murray magpie, or magpie-lark, has a white ‘eyebrow’ and a black throat) and such. Fun, and now I’m thinking about a good camera for bird-watching. I’ve also, on something of an impulse, bought a digital microscope, on its way from the USA. No idea as yet what to use it for.

Stephen-Hawking-AI-2

At a recent meetup group I had a stimulating discussion, or rather listened in on one, about the end of humanity, the various possibilities for our impending doom, the principal one being artificial intelligence. The idea is that so many things that humans are engaged in are barely in control, and that the best option for the survival of a species isn’t constant change and development, but stasis, as with trilobites perhaps, or some types of bacteria.  Since this appears not to be an option for us, some think that we’re hurtling, with all our good intentions, not towards the singularity, but towards extinction. Anthropogenic global warming, mass species extinction, human-induced epidemics, out-of-control artificial intelligence, or a combination of these might cause this event, but it was the view of one conversationalist that AI would be our undoing, and possibly quite soon. It might lead to a gradual transhumanism, which we won’t recognise until it’s too late. One of the key figures mentioned in analysis of humanity’s possibly grim future was Nick Bostrum, whose name has come to my attention from time to time. Wikipedia tells me he’s a philosopher based at Oxford, and the director of its Future of Humanity Institute. So, a person and an institute I should be conversant with for my solutions ok blog. I should probably link to it there, and it’ll mean a lot more reading and study, groan. Meanwhile, one of the arguments I heard the other night was that this could explain why we don’t find complex life out there looking for us, with their super-clever antimatter rockets and super light-speed travel techniques, because complexity of that sort beats an inevitable path to destruction. Highly-developed life-forms like us and our superiors burn with brief intensity then snuff themselves out. For us, this might be sooner than later. Hmmmm. In any case, existential risk is something I’ll have to pay more attention to in the future, if we have one.

p16om5i0se1fk61ca91qpv1urm1j30_79928

The other day I was listening to the amusing Answer Me This podcast when the name Marky Mark came up – apparently an actor, for he was chosen to star in Peter Jackson’s film The Lovely Bones. Not being too keyed in on popular culture, I’d never heard of Marky Mark (or The Lovely Bones for that matter) so I looked him up. It turned out that this was an early moniker for the actor Mark Wahlberg – whose name I’d heard of, but that was about it. Having now seen some photos of him, I don’t think I’ve seen him in anything, and I had no idea that in his early life as Marky Mark he was a notorious rapper and petty crim. But interestingly, I read that Wahlberg was now seeking a government pardon for the crimes he was convicted of as a teenager – including a few bashings of Asian-looking people. One of these incidents resulted in the victim having permanent eye damage. I don’t automatically trust too many internet sites, but the story appears to be that Marky, as a probably drug-fuelled and undoubtedly peer-influenced teen, indulged in some pretty nasty behaviour, spiced with language about ‘gooks and ‘slopes’, but he did have potential – don’t we all – and with the help of mentors he turned his life around to become, eventually, a Hollywood ‘star’. He did receive punishment for some of his crimes – and I read that he was tried as an adult for at least one of them – probably the one in which a victim lost an eye, or part of one….

I mention all this because it’s a case that raises a number of fascinating and important ethical issues. Firstly, there’s the tendency, most prevalent in the US but increasingly here too, to try juveniles as adults when they commit serious crimes, as if their ability to be fully responsible for their actions is in direct proportion to the damage they do. This smacks of a slide down the slippery slope of retributive justice – people have been really really hurt so the perp has to be really really punished, no matter that she’s eleven years old. While I have some sympathy for that attitude, and I’ll elaborate on that later, we have to accept that teenagers and children are different and that there are good, scientifically verified reasons for granting them diminished responsibility in a graded way from earliest childhood to the latest teens. The law is always a bit of a bludgeon of course, rarely taking full account of individual developmental and psychological peculiarities, which is one of the problems of ‘equality before the law’, but there’s no doubt that we generally do stupid things as teenagers and school kids, often under peer pressure, things we’d never do as mature adults. I myself got into trouble with the law for stealing, together with four or five of my friends, at the age of fourteen. We’d been egging each other on, and we perpetrated a lot more than we were charged with, but it all came crashing to a halt when we got caught. None of us were nasty brutish types, and it’s unlikely that any of us have reoffended.

Marky’s offending was rather brutish though, with serious consequences for a least one victim. His desire for a pardon is apparently driven by the fact that he’s disqualified at the moment from getting an Oscar or other accolades because of his past. Unlike me he has a permanent criminal record presumably due to being tried as an adult. He’s written a letter to government authorities wanting recognition for being an entirely different person than the one who committed those acts. Marky now does charitable work on the side like many other Hollywood stars – which is fine and dandy especially as they’re significantly overpaid for what they do and would have good reason to consider themselves bloody lucky to be in their position – but as online critics have pointed out, he’s never apologised or made reparations to his permanently-scarred victim. It goes without saying that this soul has also had a change of life since being bashed with a two-by-four all those years ago. Not much work for a one eyed Asian in Hollywood, methinks.

So this is the dilemma. Why doesn’t Marky Mark face up to the damage he did by trying to help the one person whose life he changed irreparably as an oafish teenager? That would seem to be an obvious move. And that brings me back to the treatment of serious crimes committed by persons of diminished responsibility. The reason we seek to impose harsher penalties, and for that reason to attribute greater responsibility to the young perpetrator, is because of the consequences of the crime. We believe someone has to pay for all that damage, and if not the perp, then who? It’s a really vexed question, but imposing an extremely harsh penalty on an adolescent for an extreme crime doesn’t really help, especially when the penalty, such as a prison term, will tend to harden the adolescent and make him more resentful, angry, and subject to bad influence, than he was before.

Unfortunately, we don’t live in a very forgiving society, a society which immediately seeks to help adolescents who’ve gone off the rails to the extent that Marky Mark presumably did – and I should make it clear here that I’m just using him as an example, and I’ve no idea if the facts of his case are exactly as, or even close to, what I’ve reported (I got it off the internet after all). As part of that help, he should’ve been made to face the living consequences of the damage he had done, the suffering and change he had wrought in the lives of others. But that of course would require a massive change in our system of crime and punishment. For adolescent crime though, I think it would work well, and to be fair, it does operate to some extent in some juvenile court systems, conferencing between perpetrators and victims and their families, though there isn’t enough of it, I suspect.

Written by stewart henderson

April 23, 2015 at 9:11 am

What is bluetooth?

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benefits-of-bluetooth-adapter

This is, at least sometimes, a science for dummies blog, because I’m a dummy about science and I’m here to educate myself, in a way that I’m hoping might be of interest to others.

So here’s something I’m truly ignorant of. Let me start with a definition from ignorance, then see how I can transmogrify it with a bit of research. Bluetooth is a technology used in mobile phones, computers and such, which assists in processing and communicating information more efficiently.

I don’t even know if this is a true definition, apart from its vagueness, but I expect it will have nothing to do with the colour blue or with teeth. So, it’s to Wikipedia I go, for starters:

Bluetooth is a wireless technology standard for exchanging data over short distances (using short-wavelength radio transmissions in the ISM band from 2400–2480 MHz) from fixed and mobile devices, creating personal area networks (PANs) with high levels of security.(I’ve removed the links – don’t want to make things too easy).

So now I’m slightly wiser. The short-wavelength ISM radio bands (Industrial, Scientific, Medical) are internationally reserved for the aforementioned purposes. That’s to say, to the exclusion of telecommunications.

But hang on, bluetooth is a telecommunications technology that apparently works within the reserved band. How does that work? I don’t know.

Anyhow, having read most of the Wikipedia article on bluetooth (I just couldn’t finish it), I definitely have a better understanding of the technology than I did before, despite only comprehending about 5% of the article. Still, I’m not in a position to explain it, even to myself. So now it’s time for How Stuff Works, for a less geeky guide to bluetooth. The following owes a lot to the HSW article “How Bluetooth Works”, but I’ve put it in my own words to wrap my head more tightly around the concept.

Bluetooth is a way of connecting electronic devices to each other, sans wire. You may be thinking Wifi here, but bluetooth is a quite different, though in many ways complementary, technology. It was first developed in the mid-nineties at the labs of the telecommunications company Ericsson, and has developed rapidly since then. It’s greatest advantage over other wireless systems such as the infrared technology used in most TV remotes is that it is more versatile, low-energy and low-cost – but versatility is the key. For example, infrared technology works with ‘line of sight’ – you have to point the remote at the device – and it’s essentially one-way.

Finding a way of connecting devices requires a protocol, a set of commands and responses which essentially make sense of the messages being sent between them. This protocol in Bluetooth technology requires very little transmission power, about a milliwatt of power for each transmission signal. The weakness of the signals are a key in avoiding interference in the all-important ISM band within which Bluetooth networking operates, but they limit the range to distances of about 10 metres. However, Bluetooth is not line-of-sight technology, and can be used effectively, for example, in a small house. Bluetooth can connect as many as eight devices simultaneously, but they don’t interfere with each other because of a technique called spread-spectrum frequency hopping, which means they change frequencies regularly, 1600 times per second, using 79 randomly chosen individual frequencies within a designated range. They make full use of a limited spectrum, and as each transmitting device uses this technique automatically, no two transmitters are likely to be using the same frequency at the same time. They’re also unlikely to disrupt other devices in the ISM range because of the fractional time-periods occupying particular frequencies.

Bluetooth-capable devices come within range of each other and automatically create networks known as piconets. This network may be as simple as one between a mobile phone and its headset, but these piconets, once established, frequency-hop in unison so that they can be in constant contact and can be differentiated from piconets in the vicinity.

Anyway, that’s basically as much as I need to know about Bluetooth. There are other issues around security, which can be interesting and problematic, but not too much of a concern for the average user. The automaticity of Bluetooth is one of its many pain-free advantages, and that’s apparently a help with security too. You can switch your Bluetooth mode to ‘undiscoverable’ so as to avoid contact with other Bluetooth devices, and there are other more elaborate security options.

So, with this knowledge, how do I change my world? I think the answer is – only connect.

Written by stewart henderson

December 27, 2013 at 7:57 am

Posted in magic, science, technology

Tagged with ,

fountains: how good are the acoustics of the amphitheatre at Epidaurus?

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070405_greeks_acoustics_02

The small ancient Greek city of Epidaurus, about 50 ks due south-west of Athens, was a place of pilgrimage and hope to the sick, the halt and the lame for centuries, throughout the Hellenistic period, and well into the early Christian era. It was the haunt and reputed birthplace of the healer god Asclepius, as popular as modern-day Lourdes and no doubt just as efficacious. But it’s not the healing powers of Epidaurus that I want to focus on, it’s its amphitheatre, situated a few ks out of town, and renowned for its miraculous acoustic qualities.

The theatre of Epidaurus was designed by the sculptor and architect Polykleitos the Younger and built in the 4th century BCE. It was added to in the Roman era but fell into disuse after the fall of the empire. In 1881 it was rediscovered and renovated, bringing to light for modern audiences its extraordinary acoustic properties. The term ‘amphitheatre’ means a theatre in the round, and the one at Epidaurus was one of the largest of the Hellenistic era, though the great Roman amphitheatres were larger and more visually spectacular.

When I was a kid one of the first things I ‘learned’ about the ancient Greeks was that they were great speculators and hypothesisers but not much chop at proofs and other such practicalities. I’ve been unlearning that fact ever since, and the Epidaurus amphitheatre is another step along the way. It seats around 15,000 people, and was deliberately set in the open air against a beautiful backdrop of shrubbery. But no matter where you stand or sit amongst the tiers, you’ll be able to hear a coin drop or a match being struck centre stage. Tour guides are on hand these days to prove it to you.

A 2007 study of the amphitheatre  by Nico Declercq and Cindy Dekeyser of the Georgia Institute of Technology proved that the superb acoustics were no accident.  The seating, built from limestone, filters out sound waves of low frequency, thus damping background noise from the crowd. In addition, high-frequency waves are reflected from the rows of seats, which enhances the effect. The seats had a corrugated design which acted as an acoustic trap, damping the low frequencies, but the actors’ lines could still be heard because of a phenomenon known as virtual pitch, a complex process in hearing and harmonics which enables the brain to reconstruct missing frequencies, which we do all the time on our mobile phones and other electronic gadgetry.

All of this raises the question – did Polykleitos the Younger know exactly what he was doing?  I think the only proper answer is that we’ll never know for sure. If he left any written explanations as to why the seating should be built of limestone, with corrugations in the surfaces, those explanations have been lost, along with the majority of classical and Hellenistic Greek writings. Perhaps more importantly for these speculations, Greek and Roman amphitheatres built afterwards didn’t copy the Epidaurus design features.

This doesn’t necessarily mean Polykleitos didn’t know what he was doing – though he probably didn’t know exactly what he was doing. He would likely have been experimenting with materials and designs, trying to find the right acoustic effect for an amphitheatre, You might say he was fumbling about in the dark (or the acoustic equivalent) with a specific goal in mind. It wasn’t so much a matter of chance as chance favouring the prepared mind. And it’s the preparedness of mind of so many Greek intellectuals of this era that is so impressive.

Today we take for granted a scientific approach in which we work on the findings of others in order to reproduce them or disprove them or augment them, and so build up, tiny piece by piece, a more accurate and reliable picture of how our world works. To return to the ancient Greek world is to find the first glimmerings of such an approach, along with numerous attempts to ‘reinvent the wheel’, to start from scratch, because the kind of fleshed out, multi-tested, cumulative knowledge of the world that is today’s scientific picture didn’t exist then, and the difference is such that we can barely imagine ourselves in that world. It’s only by trying to think ourselves into that context that we can appreciate the achievements of such contributors to a world we now take for granted as Polycleitos and so many others – Pythagoras, Aristotle, Theophrastus, Hippocrates, Archimedes, Eratosthenes and Heron to name but a few.

I’ll end with a reminder of the importance of scientific research and the struggle to understand our world, from Erasistratus – a physician and early researcher on the heart, the nervous system and the digestive processes – writing some 2,300 years ago:

Those who are totally unfamiliar with research, once they begin to exercise their minds, become dumbfounded and immediately abandon the pursuit out of mental exhaustion, collapsing like runners who enter a race without prior conditioning. But the person who is experienced at research keeps trying every possible approach and every possible angle and, rather than giving up after a single day’s labor, persists for the remainder of his life. Focusing on one idea after another that bears upon what he seeks, he presses on until he reaches his goal.

Written by stewart henderson

November 17, 2013 at 10:06 am