Category: slow

Categories
General Observations slow Tea

Happiness is a cup of coffee

stone recycling, slate, slate waterfall, geology
A cafe with a lovely space to enjoy the coffee. Taking time out at Espresso Base

If you are reading this, you clearly have access to a computer. You are also quite possibly connected through social media to friends, colleagues and others through Facebook, Twitter, Instagram or one of the other numerous ways in which we can now connect with each other. And while I would love for you to continue reading, at least for a couple of moments, I would like to ask you how often you take the opportunity to stop?  To stop and turn off your computer or the notifications on your smart phone and just look at what is around you.

This website is really about slowing down and noticing things. Since I believe that science offers a great way of seeing the connectedness of the world around us, I choose to emphasise the science that you can notice around you. It is most likely that you see the world in a different way, sharing some aspects of my point of view, disagreeing with others. However, it seems to me that slowing down and noticing your surroundings, whether you look at the science or another aspect of those surroundings, makes us in some way happier, or at least, generally, more calm. Having a coffee in a café is a great way of doing this. Whether you are interested in the café or the coffee (or indeed both), there is an awful lot to notice and to appreciate in a café. Noticing it of course does depend on keeping the smartphone (tablet or laptop) in your pocket or your bag. Personally, I find it slightly depressing when I see signs in a café saying “free wifi” (though I suspect I am in a minority on that one). And although if we are not used to it, not checking our email while having a coffee can seem to be enforced boredom, I’d hope that we soon realise that such boredom is in fact creative.

Sun-dog, Sun dog
Walking along while texting could mean that you miss seeing a sun dog

Please don’t get me wrong. It is not that I think social media are a bad thing. I have met (either ‘virtually’ or in person) some great and highly interesting people whom I would never have had the opportunity to meet were it not through Twitter/Facebook etc. Each day, I learn something new through the many people whose experience or knowledge I would otherwise never have had the opportunity to ‘tap’. However, just as sometimes it is great to have such interactions, I have found that it is also vital to have times (perhaps even a day a week) when the smartphone is kept firmly in the pocket (or at least, notifications are turned off).

In the UK, we have just got back from a long weekend. Many cafés were closed over the Easter break. Some of the café-Twitterers I follow went on a long break to the countryside (and Tweeted about it), others just turned off their social media for a few days. Elsewhere in the world you perhaps have different long weekends, Chinese New Year or Christmas. Perhaps during these holidays you manage to get a break in the countryside or by the coast. It is here that there is a link between an interesting recent study and a great use of a smartphone.  The study, by researchers at the University of Surrey and the London School of Economics, attempts to measure your ‘happiness’ while you are undertaking different activities in different locations, in urban environments, at work, or bird watching in the country.

Another great coffee outside, this time at Skylark cafe
Another great coffee outside, this time at Skylark cafe

Called the ‘mappiness‘ project, an app downloaded onto your iPhone (it is, sadly, only for iPhones), prompts the user to answer a question about their own perceived level of happiness at random instants. It then records the location of the phone (through GPS) and further asks the user to describe what they are doing. Over 1 million responses have so far been recorded through 20 000 participants. Perhaps unsurprisingly, the researchers have so far found that people tend to rate their happiness higher when they are outside, in natural environments and particularly in coastal areas. To me, it opens questions as to whether we should be attempting to quantify happiness or whether we should embrace the discussions of the humanities on this issue (less precise perhaps but by that very fact more complete and therefore more accurate). Perhaps these two approaches are complimentary. Nonetheless, the mappiness project remains an interesting study of a way in which you can use your phone in order to get a measure of where you should use your phone less.

Do get in touch and let me know what you think. Do you find it necessary to have some time out from social media or is Facebook your lifeline? Should cafés offer free wifi? Comments are always welcome (below) or you can get in touch by those two social media sites Twitter or Facebook. I do look forward to interacting with you there.

 

Categories
Coffee review Observations Science history slow

Reflections at Store St Espresso, Bloomsbury

Store St Espresso, coffee, Bloomsbury, UCL, London
Store St Espresso, Bloomsbury

I finally got around to visiting Store St Espresso two weeks ago while visiting the nearby Institute of Making’s 3rd birthday science-outreach party. Although the café was crowded, we managed to find a place to perch while we enjoyed a soya hot chocolate, caffé latte and my V60. Beans are from Square Mile while the V60 and filter coffee options featured guest roasters. Despite the narrow frontage, there is actually plenty of seating inside and people were happy to share tables with other customers when it got particularly busy. The café is well lit with sunlight streaming in through the sky lights above (indeed, the extra electric lighting indoors seemed a bit unnecessary given the amount of sunlight coming through the windows on such a good day). On the walls of the cafe were pieces of artwork, including quite a large pencil/charcoal piece right at the back of the cafe.

I was meeting a friend for coffee before going to the science event and so thought it would be good to combine a cafe-physics review with a visit to the science. It is always interesting to hear other people’s observations of the same space that you are ‘reviewing’. In this case, I was taken by the floor which showed some very interesting crack structures but what fascinated my friend (who was enjoying her caffe-latte) was the way that the sound from the stereo was reflecting from the bare walls, floor and ceiling. While cracks and fracture processes can be very interesting, perhaps it is worth following her observations as it leads, in a round about way, back to the coffee that she was drinking.

latte art, hot chocolate art, soya art
A caffe latte and a soya hot chocolate at Store St Espresso

While studying for my physics degree, a lecturer in a course on crystallography told us an anecdote. The story concerned a physicist walking past an apple orchard. As he was walking past, he noticed that at certain points he could hear the church bells from a distant church. As he walked on, the sound of the bells faded, before suddenly, he could hear them again. The physicist went on to derive the laws of X-ray diffraction, a technique that is now used routinely in order to understand the arrangement of atoms in crystals (like salt, diamond or caffeine). X-rays are part of the electromagnetic spectrum (just like visible light) but they have a very short wavelength.  The orchard had been inspirational to the physicist because, just as a crystal is a regular array of atoms, so the apple orchard is a regular array of trees; as you travel past an orchard (on the train, in a car or on foot), there are certain angles at which you can see straight through the trees, they have been planted in a 2D lattice. The church bells could only be heard at certain angles because of the way that the sound was being reflected from the multiple layers of the trees. The effect occurs because the sound made by church bells has a similar wavelength to the spacing of the trees (eg. ‘Big Ben’ chimes close to the note E, which has a wavelength of approximately 1m). The distance between atomic layers in a crystal is similar to the wavelength of the X-rays (the wavelength of X-rays frequently used for crystallography = 1.54 Å, size of the repeating structure in a salt crystal: 5.4 Å, 1 Å = 1/100000 of the smallest particle in an espresso grind). The physicist realised that the orchard affected the church bells in exactly the same way that the atoms in a crystal, be it salt, diamond or caffeine, will affect the deflection of X-rays. Suddenly, it became possible to actually ‘see’ crystal structures by measuring the angles at which the X-rays were scattered from substances.

bubbles on a soap solution
Not quite a regular 2D lattice. By controlling the size of the bubbles and the number of layers, you can simulate the crystal structure of different metals. Seems I need more practice in making bubbles of a similar size.

We can perhaps imagine an apple orchard but what do crystals look like? Crystals can come in many forms, all they need to be is a repeating structure of atoms through the solid. Some crystals are cubic, such as salt, some are hexagonal, others form different shapes. Metals, such as that making up the shiny espresso machine in the cafe are often a certain form of cubic structure and to visualise it, we can return to my friend’s caffé latte (via some soap). Two people who were instrumental in understanding X-ray diffraction were the father and son physicists, William Henry and William Lawrence Bragg. While attempting to make a model of crystal structures, William Lawrence Bragg found that the bubbles that could be formed on top of a soap solution were a very good approximation of the sort of crystal structures observed in metals (his paper can be found here). As they form, the soap bubbles (provided they are of similar size) form a regular cubic structure on the surface of the soap solution held together by capillary attraction, a very good model for the sort of bonding that occurs in metals. By controlling the size of the bubbles, the number of layers and the pressures on the layers of the bubbles, all sorts of phenomena that we usually see in crystals (grain boundaries, dislocations etc) could be made to form in “crystals” formed from soap bubbles. Why not look for such crystal structures in the foam of your cafe latte, though be careful to see how the size of the bubbles affects the arrangement of the bubbles through the foam structure.

Sadly, I have never found a reference to the story of the physicist and the apple orchard and it may even have been apocryphal. The closest reference I can find is that W. Lawrence Bragg (after whom the laws of X-ray diffraction are named) had a “moment of inspiration” for how X-rays would ‘reflect’ from multi-layers of atoms while he was walking in an area called “The Backs” in Cambridge. If any reader of this blog does know a good reference to this story I would be very much obliged if they could tell me in the comments section (below). To this day, I have been unable to pass by an orchard (or even a palm oil estate in Malaysia) without thinking about crystal structure, X-ray diffraction and church bells!

It seems that taking time to appreciate how sound is reflected (or diffracted) from objects, either in Store St Espresso or in an apple orchard, could be a very fruitful thing to do. If you have an observation of science in a cafe that you would like to share, please let me know here.

Store St Espresso can be found at 40 Store St. WC1E 7DB

The physics of X-ray diffraction and some great bubble crystal structures can be found in the Feynman Lectures on Physics, Vol II, 30-9 onwards.

Categories
Coffee cup science General Home experiments Observations slow

Coffee Damping

vortices in coffee
Vortices behind a tea spoon

How often do you allow yourself to get bored? Or to sit in a cafe and take your time to enjoy your coffee properly, noticing its appearance, the smell ‘landscape’ of the cafe, pausing while you absorb the sounds of the cafe and playing with the feel of the coffee while you create vortices with your tea spoon?

If you regularly drink black coffee, you may have noticed how these vortices form more easily in the coffee once the crema has dispersed. Intuitively this may seem obvious to you, perhaps you wouldn’t even bother trying to form these vortices in a cappuccino, you’d know that they wouldn’t appear. The bubbles of the crema (or the milk in the cappuccino) quickly kill any vortex that forms behind the tea spoon (we’d technically call it ‘damping’ them). But even when we are aware of this, it is still surprising just how quickly the crema stops those vortices. Try forming a couple of vortices in a region of black coffee close to a region of crema. Indeed I thoroughly recommend ordering a good black coffee in a great cafe somewhere and just sitting playing with these vortices all the while noticing how their behaviour changes as the crema disperses.

latte art, flat white art
Latte art at The Corner One. Lovely to look at but not good for the vortices.

The damping caused by bubbles on the surface of a coffee is responsible for another phenomenon that you may have encountered in a cafe but, to be fair, are more likely to have noticed in a pub. Have you ever noticed that you are less likely to spill your cappuccino between the bar and your seat than you are your lovingly prepared filter coffee? Or perhaps, in the pub, you can get your pint of Guinness back to the table more easily than your cup of tea? (At least for the first pint of Guinness)

Back in 2014, a team investigated the damping properties of foam by controlling the size and number of bubbles on top of a liquid as it was vibrated (sloshed) about. They found that just five layers of bubbles on top of the liquid was enough to significantly damp the liquid movement as it vibrated from side to side. That is, five layers of bubbles suppressed the sloshing (try saying that after a couple of pints of Guinness). Much as I dislike emphasising the utility of a piece of science, this work has obvious implications for any application that requires the transportation of liquids such as the transport of oil containers. There is an obvious need to suppress the effect of liquid oil sloshing from side to side as it is transported by boat for example.

The foam on our latte or crema on our long black should indeed give us pause for thought as we sit in a cafe enjoying our coffee.

 

 

Categories
General Observations slow Tea

Tea Gazing

Milky Way, stars, astrophotography
The Milky Way as viewed from Nebraska. Image © Howard Edin (http://www.howardedin.com)

A recent opinion piece about last week’s announcement of the detection of gravitational waves at LIGO drew my attention to a quote from Einstein:

“The most beautiful experience we can have is the mysterious. It is the fundamental emotion that stands at the cradle of true art and true science. Whoever does not know it and can no longer wonder, no longer marvel, is as good as dead, and his eyes are dimmed.“

Einstein was not the only scientist to have expressed such sentiments. Many scientists have considered a sense of wonder to be integral to their practice of science. For many this has involved gazing at the heavens on a clear night and contemplating the vastness, and the beauty, of the universe. Contemplating the twinkling stars suggests the universe outside our Solar System. Watching as the stars twinkle gives us clues as to our own planet’s atmosphere. Of course, it is not just scientists who have expressed such thoughts. Immanuel Kant wrote:

“Two things fill the mind with ever-increasing wonder and awe, the more often and the more intensely the mind of thought is drawn to them: the starry heavens above me and the moral law within me.“*

light patterns on the bottom of a tea cup
Dancing threads of light at the bottom of the tea cup.

The other evening I prepared a lovely, delicate, loose leaf jasmine tea in a teapot. I then, perhaps carelessly, perhaps fortuitously, poured the hot tea into a cold tea cup. Immediately threads of light danced across the bottom of the cup. The kitchen lights above the tea cup were refracted through hot and not-quite-so-hot regions of the tea before being reflected from the bottom of the cup. The refractive index of water changes as a function of the water’s temperature and so the light gets bent by varying amounts depending on the temperature of the tea that it travels through. Effectively the hotter and cooler regions of the tea act as a collection of many different lenses to the light travelling through the tea. These lenses produce the dancing threads of light at the bottom of the cup. The contact between the hot tea and the cold cup amplified the convection currents in the tea cup and so made these threads of light particularly visible, and particularly active, that evening. It is a very similar effect that causes the twinkling of the stars. Rather than hot tea, the light from the distant stars is refracted by the turbulent atmosphere, travelling through moving pockets of relatively warm air and relative cool air. The star light dances just a little, with the turbulence of the atmosphere, this way and that on its way to our eyes.

Marcus Aurelius wrote:

“Dwell on the beauty of life. Watch the stars, and see yourself running with them.“†

Marcus Aurelius of course didn’t have tea. Watch the dancing lights in the tea cup and see yourself sitting with it, resting a while and then watching while dwelling on the beauty in your cup.

*Immanuel Kant, Critique of Practical Reason

†Marcus Aurelius, Meditations

Categories
Coffee cup science General Home experiments Observations slow

Coffee ring bacteria

coffee ring, ink jet printing, organic electronics
Why does it form a ring?

We have all seen them: Dried patches of coffee where you have spilled some of your precious brew. The edge of the dried drop is characteristically darker than the middle. It is as if the coffee in the drop has migrated to the edge and deposited into a ‘ring’. It turns out though that these coffee rings are not just an indication that you really ought to be cleaning up a bit more often. Coffee rings have huge consequences for the world we live in, particularly for consumer electronics. Various medical and diagnostic tests too need to account for coffee ring effects in order to be accurate. Indeed, coffee rings turn up everywhere and not just in coffee. Moreover, the physics behind coffee rings provides a surprising connection between coffee and the mathematics of bacteria growth. To find out why, we need to quickly recap how coffee rings form the way they do.

When you spill some coffee on a table it forms into droplets. Small bits of dust or dirt or even microscopic cracks on the table surface then hold the drop in the position. We’d say that the drop is pinned in position.

artemisdraws, evaporating droplet
As the water molecules leave the droplet, they are more likely to escape if they are at the edge than if they are at the top. Illustration by artemisdraws.com

As the drop dries, the water evaporates from the droplet. The shape of the drop means that the water evaporates faster from the edges of the drop than from the top (for the reasons for this click here). But the drop is stuck (pinned) in position and so cannot shrink but instead has to get flatter as it dries. As the drop gets squashed, water flows from the centre of the drop to the edges. The water flow takes the coffee particles with it and so carries them to the edge of the drop where they deposit and form into a ring; the coffee ring. You can see more of how coffee rings form in the sequence of cartoons below and also here.

However in this quick explanation, we implicitly assumed that the coffee particles are more or less spherical, which turns out to be a good assumption for coffee. The link with the bacteria comes with a slightly different type of ‘coffee’ ring. What would happen if we replaced the spherical drops of coffee particles with elliptical or egg shaped particles? Would this make any difference to the shape of the coffee rings?

Artemisdraws
As water evaporates from A, the drop gets flatter. Consequently, the coffee flows from A to B forming a ring. Illustration by artemisdraws.com

In fact the difference is crucial. If the “coffee” particles were not spherical but were more elliptical, the coffee ring does not form. Instead, the elliptical particles produce a fairly uniform stain (you can see a video of drying drops here, yes someone really did video it). The reason this happens is in part due to a pretty cool trick of surface tension. Have you ever noticed how something floating on your coffee deforms the water surface around it? The elliptical particles do the same thing to the droplet as they flow towards the edge. (Indeed, the effect is related to what is known as the Cheerios effect). This deformation means that, rather than form a ring, the elliptical particles get stuck before reaching the edge and so produce a far more uniform ‘coffee’ stain when the water dries.

E Coli on a petri dish
A growing E. Coli culture. Image courtesy of @laurencebu

By videoing many drying droplets (containing either spherical or elliptical particles), a team in the US found that they could describe drying drops containing elliptical particles with a mathematical equation called the Kardar-Parisi-Zhang equation (or KPZ for short). The KPZ equation is used to describe growth process such as how a cigarette paper burns or a liquid crystal grows. It also describes the growth of bacterial colonies. Varying the shape of the elliptical particles in the drying drop allows scientists to test the KPZ equation in a controllable way. Until the team in the US started to ask questions about how the coffee ring formed, it was very difficult to test the KPZ equation by varying parameters in it controllably. Changing the shape of the particles in a drying drop gives us a guide to understanding the mathematics that helps to describe how bacterial colonies grow. And that is a connection between coffee and bacteria that I do not mind.

As ever, please leave any comments in the comments section below. If you have an idea for a connection between coffee and an area of science that you think should be included on the Daily Grind, or if you have a cafe that you think deserves a cafe-physics review, please let me know here.

Categories
cafe with good nut knowledge Coffee review General Observations Science history slow

Coffee as an art at Briki, Exmouth Market

exterior of Briki coffee London
Briki London on the corner of Exmouth Market

Traditionally made coffee always appeals to my sense of coffee history. Coffee made its way out of Ethiopea via Turkey and the method of brewing the finely ground coffee in a ‘cezve’ or ‘briki’ is one that goes back a long way. It’s therefore always interesting when a new cafe arrives on the scene that offers “Greek” or “Turkish” coffee on its menu. Briki, in Exmouth Market, opened in May last year and so it was only going to be a matter of time before I visited to try it out. Aesthetically Briki appealed to me as soon as I walked through the door. Spacious and with the bar along one wall, there are plenty of seats available at which to slowly enjoy your coffee. The cafe itself is almost triangular and the other two walls have windows running all along them. What better way to sit and enjoy the moment (and your coffee) than to gaze out a window? Still, given that I had gone to a cafe called ‘Briki’ and that it advertised “Briki coffee” on the menu behind the bar, it was obvious that I had to try the briki coffee. The coffee was rich, flavoursome and distinctive, well worth the time taken to savour it. There was also an impressive selection of food behind the counter and the dreaded “does it contain nuts” question was met with a friendly check of the ‘allergen’ folder. I was therefore able to also enjoy the lovely (nut free) chocolate cake. Briki definitely gets a tick in the “cafes with good nut knowledge” box on my categories list.

image from British Museum website
Folio 109b from an album of paintings showing Turkish sultans and court officials. Kahveci. A youth who serves coffee. He is holding a cup in each hand, circa 1620.
© The Trustees of the British Museum

However as I realised later, the coffee was not brewed in the traditional way but in a Beko coffee maker – a coffee maker specifically designed for optimising the brewing of Turkish coffee. The idea of the Beko is that it carefully controls and automates the entire brewing process so that you get a perfect coffee each time. But just how do you make a ‘perfect’ Turkish coffee?

A quick duckduckgo (it’s a mystery to me why has this verb failed to catch on while ‘to google’ is used so frequently) revealed two sets of instructions on how to make Turkish coffee. The first set, (including some otherwise very good coffee brewing websites) suggested ‘boiling’ the coffee repeatedly in the pot (cezve/briki). The second set, which seemed to be more specifically interested in Turkish coffee (as opposed to interested in coffee generally), were much more careful, even to the point of writing, in a very unsubtle way, “NEVER LET IT BOIL“. According to this second set of websites, the coffee in the cezve should be heated until it starts to froth, a process that begins at around 70C, far below the 100C that would be needed to boil it. Warming the cezve to 70C produces these bubbles and the lovely rich taste of the traditionally made coffee. Heating it to boiling point on the other hand destroys the aromatics* that form part of the flavour experience of coffee and therefore makes a terrible cup of coffee.

The contrasting instructions however led me to recall a discussion in Hasok Chang’s Inventing Temperature. Perhaps we all remember from school being taught how thermometers need two fixed points to calibrate the temperature scale and that these two fixed points were the boiling point and the freezing point of water. Perhaps this troubled you at the time: Just as with making coffee in a cezve, just how many bubbles do you need in order to say that the coffee (or water) is ‘boiling’? How were you supposed to define boiling? How much did it matter?

Cezve, ibrik, Turkish Coffee Creative Commons license
Cezve, image © http://www.turkishcoffee.us

It turns out that these questions were not trivial. There is a thermometer in the science museum (in London) on which two boiling points of water are marked. The thermometer, designed by the instrument maker George Adams the Elder (1709 – 1773) marked a lower boiling point (where water begins to boil) and an upper boiling point (where the water boils vigorously). The two points differed by approximately 4C.  So how is it that we now all ‘know’ that water boils at 100C? And what was wrong with Adams’ thermometer? The Royal Society set up a committee to investigate the variability of the reported boiling point of water in 1776. Careful control of the heating conditions and water containers reduced the temperature difference observed between different amounts of boiling. However, as they experimented with very pure water in very clean containers they found that things just became more complicated. Water could be heated to 120C or even higher without ‘boiling’. They had, unintentionally, started investigating the phenomenon that we now know as ‘superheating‘. Superheating occurs when water is heated to a temperature far above its boiling point without actually boiling. What we recognise as boiling is the escape of gas (which is usually a mix of air and water vapour) from the body of the water to its surface. In order to escape like this, these bubbles have to form somehow. Small bubbles of dissolved air pre-existing in the water or micro-cracks in the walls of the container enable the water to evaporate and form steam. These bubbles of gas can then grow and the water ‘boils’. If you were to try to calibrate a thermometer using very pure water in very clean containers, it is highly likely that the water would superheat before it ‘boiled’, there just aren’t the ‘nucleation’ sites in the water to allow boiling to start. The Royal Society’s committee therefore came up with some recommendations on how to calibrate thermometers in conditions that avoided superheating which meant thermometers were subsequently calibrated more accurately and superheating (and improved calibration points) could be investigated more thoroughly.

Perhaps viewed in this way there are even more parallels between Turkish coffee and physics. It has been written that “making Turkish coffee is an art form“. It is a process of practising, questioning and practising again. The Beko coffee machine automates part of the process of making Turkish coffee. When it’s done well though, Turkish coffee is far more than just the temperature control and the mechanics of heating it. There is the process of assembling the ingredients, the time spent enjoying the coffee and the atmosphere created by the cafe in which you drink it. Coffee as art in Briki is something that I would willingly spend much more time contemplating.

 

Briki is at 67 Exmouth Market, EC1R 4QL

“Inventing Temperature”, by Hasok Chang, Oxford University Press, 2004

*Although these aromatics are part of what gives coffee such a pleasurable taste, they decay very rapidly even in coffee that is left to stand for a while, it is this loss of the aromatics that is part of the reason that microwaving your coffee is a bad idea. A second reason involves the superheating effect, but perhaps more on that another day.

 

Categories
General Science history slow

Ghosts of Christmas Past, the Devereux

Grecian, Coffee House, London Coffee House
The Devereux now stands where the Grecian once was

The Grecian is steeped in history. One of London’s early Coffee Houses, it counted Isaac Newton and Edmond Halley among its regulars. Today it is the site of a pub, “The Devereux“, owned by Taylor-Walker. The building itself dates from the nineteenth century though it is on the site of the old Grecian (a drawing of which can be seen on a wall inside the pub). In a sense, the Devereux is a continuation of the Grecian that once existed on this spot and it is for this reason that I’ve wanted to enjoy a drink at the Devereux/Grecian for a long time. What better time to do it than for a Christmas themed cafe-physics review?

The Devereux itself is a fairly spacious, comfortable pub, tucked down a little alley just off Fleet Street. It is strange to consider (while sipping on a glass of the 1730 pale ale) that it was here, just over 300 years ago, that the Grecian would host the after-meeting “pub outing” of the (then newly formed) Royal Society. Paintings and photographs of the Grecian and the Fleet St. area surround you, as you sit and enjoy your drink (they do serve tea and coffee too). Indeed, it is possible to almost feel the history of this place. I recalled reading a 1686 paper in the Philosophical Transactions by Edmund Halley in which he described a live demonstration, in front of a meeting of the Royal Society, of just how much water could evaporate from a heated plate of water in two hours. Halley was interested in this as part of the whole question of how rivers formed and where rain came from. I wondered whether Halley and his friends Newton and Sloane, retired to the Grecian after that meeting and sipped on hot coffee as they sat next to the cold windows which started to steam up on the inside.

Vegetable Lamb, Lamb of Tartary
The Vegetable Lamb in the collection of The Garden Museum

Reading about these early frequenters of this drinking establishment, it is hard to avoid the impression that they were driven by an interest in knowledge and knowing things. Of course the term ‘scientist’ had not yet been invented*. Science as in ‘scientia’ was still just Latin for knowledge, the men who gathered at the Grecian (and they were mostly men) were not “scientists” they were Natural Philosophers. Hans Sloane, another regular, was a great collector, finding curiosities from around the world and displaying them in his house. Most of his collection became the start of the British Museum but there is one curiosity of Sloane’s that I came across recently that is not to be found there at all and that is his “Vegetable Lamb”.

Vegetable Lambs were believed, in the seventeenth century to be, genuinely, part vegetable part animal. You can see from the photo that they do look fairly animal-like. According to the Garden Museum, these vegetable lambs originated in the Far East but now only two remain in the UK. The one that belonged to Hans Sloane (which is in the Natural History Museum) and the one that belonged to John Tradescant and that can now be found in the Garden Museum (now sadly closed until refurbishment is complete in 2017). Hans Sloane’s contribution was to show that this vege-animal was in fact purely a plant, a type of fern, which may make vegetarians everywhere breathe a sigh of relief. It was because these people were interested that they worked so hard in trying to understand the world around them. Which brings us, somewhat surprisingly, to one of the more recent famous patrons of what had by that time become, the Devereux.

Chesterton
The festive Chesterton bookshelf at the Devereux

GK Chesterton is not known for his scientific research. However, he did spend a great deal of time thinking and writing about all sorts of things. (It also appears that he spent a fair amount of time in the Devereux where there is an entire bookshelf of his books). A book of Chesterton’s essays “As I was saying” was published in the year of his death, 1936. Within that book is an essay “About the Telephone”. Chesterton was musing on a sentence that he had read in a newspaper that had troubled him: “The time will come when communicating with the remote stars will seem to us as ordinary as answering the telephone”. Chesterton wrote “Now if you could say to me: ‘The time will come when answering the telephone will seem to us as extraordinary as communicating with the remote stars…’ then I should admit that you were a real, hearty, hopeful, encouraging progressive.” I suspect that with our tendency today towards the fragmentation of knowledge and increasing specialisation, we would categorise the work of Newton and Halley, Sloane and then Chesterton in quite different compartments. Yet it seems to me that they share something in their work: an element of wonder and curiosity at the world. As Chesterton continued in “About The Telephone”,  “I am not objecting to the statement that the science of the modern world is wonderful; I am objecting to the modern world because it does not wonder at it.“

It sometimes seems hard for us to sit in a cafe on our own without using, or at least looking at, our telephones. Checking our email or the latest news on our telephones has become extraordinarily ordinary for us. Maybe this should be our New Year’s resolution: put our phone back into our pocket and consider, with Chesterton, Sloane, Halley and Newton, just how wonderful it is.

Happy Christmas & New Year to all

 

* The word science/scientist was first used in the sense that we now understand it by William Whewell in the nineteenth century.

“As I was Saying – a book of Essays by GK Chesterton” was published by Methuen&Co Ltd, 1936

The Devereux can be found in Devereux Court, just off Fleet Street, WC2R 3JJ

Categories
Home experiments Observations slow Tea

Coffee baubles

resonating coffee
Not the best image of a resonating coffee but you hopefully get the idea

Most people, at some point in their lives, must have pushed a take-away coffee cup across a table and watched as patterns form on the liquid surface. Sometimes these patterns seem to stand still, we’d say that they form ‘resonances’. On even rarer occasions, on dragging your cup across the surface, you may have seen coffee droplets jump out of the coffee and then dance on the coffee surface for a couple of seconds as the liquid vibrates.

Today’s Daily Grind investigates these ‘floating droplets’ with an experiment in time for Christmas: Decorate your coffee with coffee baubles.

To make these droplets form on your coffee in a controllable way you will need a few bits of equipment:

  1. A couple of loud-speakers with the woofers exposed
  2. Some sort of liquid soap (washing up liquid, hand soap, soap for hand washing clothes etc)
  3. Some water (or coffee but you will do horrible things to it)
  4. A shallow dish (I used the bottom of an old yoghurt pot)
  5. A “dropper”, a pipette or syringe would be ideal, a straw will probably work.

You can do this completely systematically, in which case you’ll also need a signal generator to provide a fixed frequency output to the speakers (I used “ScorpionZZZ’s Lab, Signal Generator Lite for iPhone). Or you can just go straight to the fun bit which is to make these droplets dance to music. It’s Christmas so it’s entirely up to you!

floating drops, resonances, speakers, kitchen top science
Balance a shallow dish on the woofer of a speaker. A roll of sellotape can be used to couple the vibrations of the speaker to the dish if necessary.

Balance your speakers on a flat surface and put the shallow dish so that it sits in good contact with the woofer. Because my dish was ever so slightly larger than the vibrating bit of the speaker, I ‘coupled’ the speaker to the dish with a roll of sellotape. Mix 10ml of soap with 100ml of water (this does not have to be exact but you may want to investigate just how much/little soap you can get away with). If you are using coffee rather than water, you will need to mix 10ml soap with 100ml coffee.

Pour about half the soapy-water into the dish and then turn the speakers on. If you are using a signal generator, watch what happens as you sweep the frequency from 10-200 Hz. Now, either choose a frequency which shows a nice resonance pattern on the water, or start playing the music through the speakers. Music with a good beat will work well (I watched drops dance to Tiesto, Blondie, and Josh Woodward’s “coffee”).

Drip a drop of the remaining soapy-water onto the resonating surface. A video of my playing with these droplets can be seen above. Although not all the drops will float, it is fairly easy to start to form patterns of flowers or rows of droplets and then it’s worth just playing.  How big a droplet can be made to float without collapsing? How many minutes can you get a drop to last before it sinks? What happens if you combine a drop of black (soapy) coffee with a drop of milky (soapy) coffee?

Have fun, and please do share your videos and photos of your experiments with me on Facebook or Twitter.

Disclaimers & Credits:

No coffee was wasted in the making of this video. A very good coffee from Roasting House was thoroughly enjoyed before the remnants were diluted and mixed with soap.

Inspiration & experimental details taken from Jearl Walker’s great article “The Amateur Scientist” in Scientific American, p. 151 (1978).

 

Categories
General Observations slow Sustainability/environmental

A drop in the Chemex?

Chemex, 30g, coffee
How do you prepare your coffee?

How do you prepare your coffee? Generally I’ll either use the Chemex or a French press. Often it will be the French press purely because it is, sadly, quicker. However, on those mornings that I do slow down to prepare a Chemex, I generally feel better for it. Not only does the coffee taste better, but those 5 minutes of preparing the coffee pay off as time for the mind to wander rather than just time spent waiting for the caffeine. When the Chemex is nearly ready, the fresh brew drips slowly from the filter onto the liquid below. Each drop produces a ripple pattern. At the start of the UN conference on climate change in Paris (COP21), we may well hear talk of some of our efforts being mere “drops in the ocean”. So it seems a good time to reflect on those “drops in the Chemex”. Just how much influence can a drop  have?

It is worth stopping for one moment to consider what is going on around us at this moment. As I write this, it is late November in the Northern Hemisphere. Taking a walk outside, I can see the last of the yellow leaves falling off the trees. In just a couple of weeks time, many of the trees will be bare. Why do the leaves fall from the trees? We could answer this question in a number of different ways. Biologically, the tree is forming cells at the joint between the leaf and the tree that will eventually enable the leaf to tear from the tree. As these cells are, in some way, responsible for the leaf falling off, they are called “abscission” cells. But even with these abscission cells, the leaf still needs something to force the leaf off. Often this is the wind which is why we get such an abundance of leaf fall on windy days. However there is another mechanism that can help a leaf to drop, and that is a curious interplay between the leaf and rain.

autumnal scene, red leaves, hydrophilic
The surface of the leaf changes from waterproof to ‘wettable’ over the course of the summer

In the spring, many species of tree, including Oak, develop a wax layer on the leaf. Perhaps you have been walking in the country and have needed to wax your walking boots before you go? The wax on the boots acts as a waterproofing for the boot, ensuring that your feet don’t get soggy. The wax on an oak leaf performs the same function for the leaf, it makes the leaf waterproof. Although this is not the only function of the wax. It seems that a waxy surface also slows the processes that dry out the leaf, prevents insects and pathogens attacking the leaves and may even play a role in affecting the way that the light is concentrated into the leaves for photosynthesis. Nonetheless, from the tree’s perspective, it is a significant advantage to have waterproof leaves. Imagine rain falling onto a waterproof surface. The drops of rain do not ‘wet’ the leaves but instead roll off. As the raindrops roll off, they take particles of dust and dirt with them. It is a tree’s way of cleaning itself. Waterproof surfaces are self-cleaning surfaces. Something that some scientists are now trying to replicate for man-made products.

hydrophobic leaves
Some leaves are more waterproof than others.

As the summer continues and the leaf gets older, the wax layer changes. The structure of the wax changes and erodes as the wind, weather and even pollution batter the wax layer. Just as with the hiking boots, the damaged wax layer results in a less waterproof leaf. The leaf becomes “wettable”. When a drop falls on a surface, the shape of the droplet is determined by how waterproof the surface is (more details here). A surface is termed “wettable” when the droplet becomes significantly flatter and coats the surface rather than forming a spherical drop that can roll off. Now consider each raindrop as it hits the different types of leaf. In the spring, the leaf is waterproof and the raindrops will roll off them. A drop of rain will cause the leaf to shake on its stem but then to return to its original position. It is ultimately not affected by a light rain shower. In the autumn when the leaves are no longer waterproof, the rain will start to stick to the leaf surface. Now when the leaf shakes, the wet leaf will not return to its original position but will bend slightly further downwards. As it continues to rain, the leaf will experience a greater torque and this means that it is more likely to fall off the tree. As each rain drop hits the leaf, the likelihood that the leaf will tear away from the abscission cells at the base of the leaf increases. Each drop has an effect.

This also has an important consequence for some of our technology. One renewable energy source that has been proposed for self-powering electronic devices harnesses the energy of rain. When rain falls on an array of cantilevers, it forces the cantilever to bend and to oscillate. This energy can be harvested ( that is, changed into a form that is useful to us) by using small piezo-electric devices (that convert movement into electricity or vice versa) at the  base of the cantilever. When a tree leaf is wet, the leaf joint experiences a greater torque which causes the leaf to ultimately tear from the tree. For the rain-energy harvesters, this is exactly what we want. The greatest energy obtainable from the cantilever system will be from cantilevers that can be made wet. Waterproof cantilevers would be a bad idea. A renewable energy that comes from rain would definitely be a positive development for UK energy production!

It seems that one coffee drop does indeed go a long way.

 

Categories
General slow

What is a good coffee?

Sun-dog, Sun dog
A photo to suggest happiness? Spotting sun dogs makes me happy.

A few weeks ago, an opinion piece appeared in a UK newspaper with the title “Scientists find nirvana as hard to explain as to attain”. The article was about the launch of a course, endorsed by the Dalai Lama, by the group ‘Action for Happiness‘ and the release that week of the Office of National Statistics League table of personal well-being. While happiness and well-being are both evidently things that we want to encourage, what do we mean by quantifying well-being into a league table?

It seems to be part of what can be a tendency to ‘scientise’ aspects of our lives and experience, aspects that are clearly, when we think about them, not described by science. Coffee is not immune from this. Studies have been made of how we feel about drinking our coffee based on whether we drink coffee for pleasure or for the caffeine kick. Why is it that we feel the need to quantify something in order to demonstrate that we have an understanding of it? Does labelling something as ‘scientific’ give it greater credibility?

As described elsewhere, part of the thinking behind Bean Thinking is to explore the beauty and the connectedness that an appreciation of the science in a coffee cup can give us. But there is an important corollary to this. It is to celebrate the contribution of those other aspects of our thinking that allow us to appreciate beauty: Art, literature, history. Beauty is not a quantity that can be defined scientifically (although we all seem to have a mutual appreciation of beauty and, surprisingly often, of what is beautiful). Happiness is similar. We have an understanding of what happiness is but a quantitative evaluation of happiness eludes us.

good coffee, nun mug, Ritzenhoff
How would you define a good coffee?

In hindsight it seems that, entirely unintentionally, the tagline of Bean Thinking captured both of these aspects of meaning. “Where entertaining science meets good coffee“: Hopefully it is fairly easy to find the science on the website but good coffee? What do we mean by ‘good’. Is my version of “good” coffee the same as yours? Is ‘good’ in this context something that can be quantified (acidity, aroma etc) or something more, a word that incorporates aspects of the living conditions of the farmers who grow the coffee and the workers who pick the cherries at harvest time? In attempting to understand what is a ‘good coffee’ we may be tempted to define good as being a coffee having certain properties, a pH around X, a quantity of caffeine around Y and a fraction of 2-furfurylthiol (a chemical which contributes to coffee’s pleasurable aroma) of at least Z. This is a route that will lead us to instant!

But joking aside, by narrowly defining the word ‘good’ so that we feel that our understanding of it is scientific and therefore irrefutable, we have lost what we originally meant by good. Science is an important tool, one that helps us to understand (and to control) the world around us but it is not a philosophy. We can never use science to define a ‘good coffee’ in a way that we would all recognise as a good definition of good. Of course science can help us to decide aspects of a good coffee (the pH, the caffeine content etc. all contribute to a good cup) but we cannot use it, of itself, to define a good cup. The same must go for happiness and other aspects of our lives (can we measure a good school by its position in a league table for example?). We must always be on our guard against over-stating the proper limits of science. We cannot use it in defence of a metaphysical position. The strength of science lies in its being a key part of our tool box for examining and understanding the world.

Fish in a tank
Fish in a tank

Admitting that aspects of our definition of a good coffee are qualitative, arguable or even “subjective” does not devalue the meaning of the word good. The same applies to happiness and many other areas. Quantifying something can mean that we understand it less. Midgley has an interesting analogy in this context of the roles of different areas of our thought:

“[An image that is helpful] is that of the world as a huge aquarium. We cannot see it as a whole from above, so we peer in at it through a number of small windows. Inside, the lighting is not always good and there are rocks and weeds for the inhabitants to hide in. Is that the same fish coming out that we saw just now over there? And are those things stones or starfish? We can eventually make quite a lot of sense of this habitat if we patiently put together the data from different angles. But if we insist that our own window is the only one worth looking through, we shall not get very far.“*

According to the ‘quantitative’ measurement of well-being in the ONS survey, London is a relatively miserable place. The Action for Happiness group runs a Happy Cafe network which includes two London cafes: The Canvas and The Skittle Alley Coffee & Pantry. I have no idea as to whether such cafes can help us to live happier and more meaningful lives. I do know however that I won’t be able to find out whether they do so ‘scientifically’. I also know, that slowing down and spending five minutes contemplating my coffee, wherever I am, will help me to develop into a more rounded person. I am unable to define (scientifically) what I mean by rounded.

If you have a good definition of good, why not share it in the comments section below. Alternatively, if you are enjoying five minutes (or more) in a great cafe with something about it that is interesting to notice, why not think about writing it as a cafe-physics review?

* “The Myths We Live By”, Mary Midgley, was published by Routledge Classics, 2004