Category: Science history

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Coffee review Science history slow

Coffee & temperance at the Penny, Old Vic

inside the Penny Old Vic
Coffee at the Penny

A café with good coffee in a theatre? I admit to being a little dubious when I first read about Penny at the Old Vic. Fortunately, there was no reason to be concerned. Penny serves Workshop coffee in an unusual setting (even accounting for the fact it is in a theatre). Going through the doors to the Old Vic, you turn left and head down a staircase to the basement where a long counter stretches out in front of you and to your right. Being a theatre café, there were a wide selection of snacks, bar meals, beer and wine in addition to the coffee being served with the La Marzocco espresso machine. As you’d expect, the usual range of coffees were on offer but if you prefer non-dairy milk, there was oat and almond available in addition to the more usual soy based milk. (Although almond milk is one to watch for if you have a tree-nut allergy as there is a risk of cross contamination).

There was also a wide selection of chairs and tables to choose from, ranging from a standard table, to a high table with stools and, around the corner, some chairs that look like you can sink into them and enjoy your coffee way after the performance has been called. The café is open all day (in fact from 8am until 1am on week days) and, if you are not there during a performance is quite spacious (though during the intervals it could probably get quite crowded).

staircase, Old Vic
The lighting on the staircase periodically got brighter and then dimmer. How easy is it to keep our national electrical supply constant such that blackouts and brownouts are not a problem?

The café certainly provides a service for good coffee in Waterloo (it’s within 5 minutes walk from the station) and it is a great place for refreshment if you are visiting the theatre, but is it also the sort of place at which you can slow down and enjoy the moment? The type of neighbourhood café where you can sip your coffee while letting your mind wander onto a café inspired thought train? At first glance, it is perhaps unpromising as it has clearly been renovated and made to be a modern café. But then, thought trains do not happen “at first glance” but as a result of slowing down, sitting, watching and absorbing the surroundings. It is as you do this that I think Penny at the Old Vic starts to speak to you.

The first thing that you may notice is the lighting. A number of different types of lightbulb including an industrial looking art-piece on the stairwell coupled to what appeared to be natural light coming down through another staircase. This theatre was first built in 1816-1818¹ (but with significant rebuilds since then), how was the stage lit at that time? Where did the theatre patrons go to get a cup of coffee or a glass of wine between the scenes and how could they see anything in the dark?

Around 3.5 miles away, one of the first housing developments to have electric lighting was being constructed in the 1860s. The electricity was supplied by seven steam engines housed in a building just off High St Kensington and sent to the new development next door, “Kensington Court”¹. Evidence of the electrical power station (which supplied DC not AC electricity) can still be seen on a stone sign on the building alerting passers by to the “Electric Lighting company”. It is probable that no such set of steam engines provided power for the lighting in the Old Vic, which was more likely still run on candles and gas lighting. However, it is something that was nearly contemporary with the development of Kensington Court that gives this post its title. It is also the reason behind the name of the cafe.

Soya hot chocolate at the Penny, Old Vic
Lord Kelvin got thinking about viscosity as a consequence of drinking a hot chocolate.

In the 1880s, a woman called Emma Cons took control over what is now the Old Vic. When she ran it, the theatre was called the “Royal Victoria Hall and Coffee Tavern” and ran ‘morally decent‘ productions for local people (note though the importance of the coffee to the project!). These productions included scientific lectures for which the entrance fee was a penny, hence, apparently, the Penny café. Apparently she also ran science classes in the disused dressing rooms and, though the mind boggles as to what experiments were done in this theatre at that time, the classes and the lectures were so popular that soon, Cons founded Morley College to continue this adult education. Morley College continues as an adult education college to this day and is now one of London’s oldest adult education colleges.

So it would appear that, even though the Penny café is a relatively new addition to the Old Vic theatre as we know it, the associations between the theatre and coffee (and the theatre and science) go back a long way. First appearances can be deceptive and, with good coffee and much to ponder, the Penny is definitely one to sink into a chair and to listen.

Penny café is in the Old Vic Theatre, The Cut, Waterloo, SE1 8NB

Inside the Penny
Penny at the Old Vic.

¹The London Encyclopaedia, 3rd Edition

Categories
General Home experiments Observations Science history slow

Theme on a V60

bloom on a v60
V60 bubbles. There is much to be gained by slowing down while brewing your coffee.

Preparing a coffee with a pour-over brewer such as a V60 is a fantastic way to slow down and appreciate the moment. Watching anti-bubbles dance across the surface as the coffee drips through, inhaling the aroma, hearing the water hit the grind and bloom; a perfect brewing method for appreciating both the coffee and the connectedness of our world. The other week, while brewing a delightful Mexican coffee from Roasting House¹, I noticed something somewhat odd in the V60. Having placed it on the kitchen scales and, following brewing advice, measured the amount of coffee, I poured the first water for the bloom and then slowly started dripping the coffee through. Nothing unusual so far and plenty of opportunity to inhale the moment. But then, as I poured the water through the grind, I noticed the scales losing mass. As 100g of water had gone through, so the scales decreased to 99g then 98g and so on. It appeared the scales were recording the water’s evaporation.

science in a V60
Bubbles of liquid dancing on the surface of a brewing coffee.

It is of course expected that, as the water evaporates, so the mass of the liquid water left behind is reduced. This was something that interested Edmond Halley (1656-1742). Halley, who regularly drank coffee at various coffee houses in London including the Grecian (now the Devereux pub), noted that it was probable that considerable weights of water evaporated from warm seas during summer. He started to investigate whether this evaporating vapour could cause not only the rains, but also feed the streams, rivers and springs. As he told a meeting of the Royal Society, these were:

“Ingredients of a real and Philosophical Meteorology; and as such, to deserve the consideration of this Honourable Society, I thought it might not be unacceptable, to attempt, by Experiment, to determine the quantity of the Evaporations of Water, as far as they arise from Heat; which, upon Tryal, succeeded as follows…”²

Was it possible that somehow Halley’s demonstration of some three hundred years ago was being replicated on my kitchen scales? Halley had measured a pan of water heated to the “heat of summer” (which is itself thought provoking because it shows just how recent our development of thermometers has been). The pan was placed on one side of a balance while weights were removed on the other side to compensate the mass lost by the evaporating water. Over the course of 2 hours, the society observed 233 grains of water evaporate, which works out to be 15g (15 ml) of water over 2 hours. How did the V60 compare?

Rather than waste coffee, I repeated this with freshly boiled water poured straight into the V60 that was placed on the scales. In keeping with it being 2017 rather than 1690, the scales I used were, not a balance, but an electronic set of kitchen scales from Salter. The first experiment combined Halley’s demonstration with my observation while brewing the Mexican coffee a couple of weeks back. The V60 was placed directly on the scales and 402g of water just off the boil was poured into it. You can see what happened in the graph below. Within 15 seconds, 2 g had evaporated. It took just a minute for the 15g of water that Halley lost over 2 hours (with water at approximately 30 C) to be lost in the V60. After six minutes the rate that the mass was being lost slowed considerably. The total amount lost over 12 minutes had been 70g (70ml).

evaporation V60 in contact with scales
A V60 filled with 400g of water just off the boil seemed to evaporate quite quickly when placed directly on the scales.

Of course, you may be asking, could it be that the scales were dodgy? 70g does seem quite a large amount and perhaps the weight indicated by the scales drifted over the course of 12 minutes. So the experiment could be repeated with room temperature water. Indeed there did appear to be a drift on the scales, but it seemed that the room temperature water got moderately heavier rather than significantly lighter. A problem with the scales perhaps but not one that explains the quantity of water that seems to have evaporated from the V60.

control
Hot water (red triangles) loses more mass than room temperature water (grey squares).

Could the 70g be real? Well, it was worth doing a couple more experiments before forming any definite conclusions. Could it be that the heat from the V60 was affecting the mass measured by the electronic scales? After all, the V60 had been placed directly on the measuring surface, perhaps the electronics were warming up and giving erroneous readings. The graph below shows the experiment repeated several times. In addition to the two previous experiments (V60 with hot water and V60 with room temperature water placed directly on the scales), the experiment was repeated three more times. Firstly the V60 was placed on a heat proof mat and then onto the scales and filled with 400g of water. Then the same thing but rather than on 1 heat proof mat, three were placed between the kitchen scales and the V60. This latter experiment was then repeated exactly to check reproducibility (experiment 4).

You can see that the apparent loss of water when the V60 was separated from direct contact with the scales was much reduced. But that three heat proof mats were needed to ensure that the scales did not warm up during the 12 minutes of measurement. Over 12 minutes, on three heat proof mats, 14g of water was lost in the first experiment and 17g in the repeat. This would seem a more reasonable value for the expected loss of water through evaporation out of the V60 (though to get an accurate value, we would need to account for, and quantify the reproducibility of, the drift on the scales).

V60 Halley
The full set: How much water was really lost through evaporation?

Halley went on to estimate the flow of water into the Mediterranean Sea (which he did by estimating the flow of the Thames and making a few ‘back of the envelope’ assumptions) and so calculate whether the amount of water that he observed evaporating from his pan of water at “heat of summer” was balanced by the water entering the sea from the rivers. He went on to make valuable contributions to our knowledge of the water cycle. Could you do the same thing while waiting for your coffee to brew?

Let me know your results, guesses and thoughts in the comments section below (or on Twitter or Facebook).

¹As this was written during Plastic Free July 2017, I’d just like to take the opportunity to point out that Roasting House use no plastic in their coffee packaging and are offering a 10% discount on coffees ordered during July as part of a Plastic Free July promotion, more details are here.

²E Halley, “An estimate of the quantity of vapour….” Phil. Trans. 16, p366 (1686-1692) (link opens as pdf)

Categories
Coffee review General Observations Science history Tea

In the loop at Coffee is my cup of tea

exterior coffee is my cup of tea, cimcot, coffee Hackney
Coffee is my cup of tea on Dalston Lane. The colour of the exterior matches the crockery used inside.

There is a lot of truth in the name of this café. “Coffee is my cup of tea” in Hackney is a lovely retreat, a place where you can take time to enjoy whatever drink is your cup of tea. Walking through the door, you are presented with a few wooden tables and a cocktail menu on the wall. A breath of calm on an otherwise busy road. Together with the bench just outside, there is plenty of seating inside. There’s even a long table along the window where you can sit if you would like to enjoy your coffee while gazing at the passers-by. There were the usual range of coffees on offer along with fresh juices, other drinks together with a range of food. When we went in the late afternoon, there didn’t seem to be many cakes on offer but maybe we were just unlucky. Coffee only this time. The coffee is roasted by Assembly and there is of course tap water available at the end of the bar.

Facing the bar, glued to the wall, were a circle of stiletto shoes. Forming what seemed to  be a “shoe star”, they were one of a number of art works around the shop. The café is also quite spacious, the window at the front providing plenty of light and contributing to the relaxed space. When my long black arrived, the light coming in from the windows produced great interference patterns on the bubbles of the coffee, an irresistible piece of coffee physics. The cocktail menu provided quite a distraction, again making the point that it was a shame we visited on an afternoon: an evening of coffee and cocktails would make a lovely night. However, a sunny afternoon was a great time to sip and enjoy a long black. While the long black started off very fruity, the taste changed (matured?) as the temperature of the coffee decreased. In the background to this all though, something so subtle as to be almost un-noticeable caught my attention. Completely surrounding the window was a very thin piece of copper wire. Were there tiny little lights on it to make the café more attractive (romantic even?) in the evening? I couldn’t see any. From our table, it seemed as if it was just a thin, closed loop of copper wire forming a loop around the window.

coffee cimcot
Fantastic interference patterns on the bubbles of the coffee at Coffee is my cup of tea

Such a loop could be used as a radio antenna, a “loop antenna”. Indeed, when Heinrich Hertz (1857-1894) first discovered radio waves in 1887-8, he used a (gapped) loop antenna as the receiver. Hertz had been trying to test James Clerk Maxwell’s theory that visible light was part of a much broader spectrum of electromagnetic waves, particularly, that there should exist very low frequency waves far beyond the visible region of the spectrum, waves that we now know as “radio waves”. Radio, TV, wifi, all things that seem so obvious now but were really only predicted and discovered relatively recently. Working in his laboratory in Karlsruhe, Hertz set up a radio generator which consisted of two brass balls that were charged until a spark flashed between them. Sitting a few metres away, a gapped loop of wire, the ‘loop antenna’ suddenly showed a spark over the gap. The spark that Hertz had generated in one part of the room had been mysteriously transmitted, as if through an aether, to be picked up by the antenna a few metres away. Clearly it was consistent with Maxwell’s predictions. The electric spark had generated a low frequency electromagnetic wave that had been picked up with the loop antenna. With further experiments, Hertz showed that this wave was indeed reflected and refracted in the same way as ordinary, visible, light and even determined its wavelength (which for Hertz’s experiment was about 66cm)¹.

loop antenna at cimcot, Dalston Lane
It is probably easiest if you visit the cafe but look very very closely at the frame of the window. There is a copper wire surrounding it.

Although Hertz did not immediately see any practical application of his result (beyond the fact that it was a test of Maxwell’s theory of light), ‘radio’ soon started to be developed. Marconi and others worked with wavelengths of 200-600 m to transmit radio waves across the Atlantic Ocean¹. As amateur radio enthusiasts got hold of radio sets in the 1920s they started working with wavelengths that were initially considered impractical for applications (much shorter than the hundreds of metres used by Marconi). These enthusiasts soon realised that they could communicate with other enthusiasts in distant countries through the reflection of the radio waves off of the (until then unknown) ionosphere¹. Gradually our understanding of radio waves and antennae design developed, leading to further, unexpected applications. Depending on the design of the antennae, radio waves (and microwaves, which have a slightly shorter wavelength of the order of 0.1-100cm*) could be made to be directional. So antennae could be made that transmitted waves only in set directions (or conversely could detect the direction from which radio/microwaves originated). This understanding of antennae design would lead to advances in Radar technology.

Which brings us back to the loop antenna at Coffee is my cup of tea. Loop antennae are grouped into two types, “small” and “large”. It is fair to say that it is a large window at Coffee is my cup of tea and so the loop antenna there would fit into the “large” category. These antenna are ‘resonant’ (meaning that they respond most) to wavelengths equal in length to the circumference of the antenna. From memory, I’d guess that the window was roughly 2m high and 3 m across, meaning it had a circumference of 10 m. We can calculate the frequency of the radio waves that would be resonant with this by using the fact that the frequency (f) is just the speed of light (c) divided by the wavelength (λ) (ie. f=c/λ). The speed of light is 3×10^8 m/s, so the frequency would be (3×10^8)/10 = 30 MHz. There are two last things to notice about this result. First, the name of Hertz lives on in the unit of frequency (Hz). Secondly, the loop antenna around the window at Coffee is my cup of tea is resonant with approximately the frequency of Citizens Band radio (CB radio operates at ~27 MHz). Which may make us question once more what this loop of wire is doing at this friendly little café on Dalston Lane.

Coffee is my cup of tea can be found at 103B Dalston Lane, E8 1NH

¹Britain’s shield radar and the defeat of the Luftwaffe, David Zimmerman, Amberley publishers (2001, 2010)

*Technically Hertz discovered microwaves rather than radio waves. However, given neither were named at the time and they are both of longer wavelength than visible light, it is perhaps too pedantic a point.

 

Categories
Coffee cup science General Home experiments Science history Tea

Reading tea leaves with Einstein and my great-grandmother

tea pot science
It’s not just tea, Einstein is famous for some other physics too

Ask anyone what Albert Einstein is famous for and you’ll probably (hopefully) hear that he came up with the theory of relativity (special and general). Perhaps you may also be told that he came up with a little theory explaining the photoelectric effect for which he won the Nobel prize in 1921. Maybe, if you have read this website before, you will know that he contributed to our understanding of Brownian motion, which is a phenomenon that is frequently found in a coffee cup. But it turns out that Einstein wrote another paper, far more important than any of these others, which was about tea. Or at least, I suspect my great-grandmother would have found it more important than any of these others as it coincided with a special hobby of hers, reading tea leaves.

It seems that my great-grandmother used to enjoy reading tea-leaves. Whether it was something she had learned as a child or merely used as an interesting trick to perform at family functions, stories of her examining the patterns formed by swirling tea leaves in a cup have come down to us in younger generations. Einstein too had noticed the patterns formed by the tea leaves in the cup and had observed a problem. The problem is this: If you drink a cup of (inadequately filtered) loose leaf tea and stir it, the tea leaves collect in a circle in the middle of the base of the cup. At first this may appear counterintuitive. When we stir things, don’t things fly outwards towards the edge of the cup rather than inwards to the centre of the circle? Why is it that the leaves collect in the middle?

Thames, NASA image
How do rivers erode? What causes a river to meander? The meandering Thames, photographed by NASA, Image courtesy NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

For Einstein, this tea leaf problem was connected to another phenomenon, the erosion of rivers. But it turns out that the problem is also linked to issues found in beer brewing and blood tests, and it seems, in how to poach an egg. To see the solution and therefore the connections, we need to think a bit more about how water flows. One of the brilliant lines in Einstein’s paper starts “I begin with a little experiment which anybody can easily repeat.” This experiment is to obtain a flat bottomed cup of tea with some tea leaves at the bottom of it. Now stir the tea and watch how the leaves settle, Einstein continues “the leaves will soon collect in the centre of the bottom of the cup“.

The explanation is connected with the fact that at the walls of the cup, the liquid (tea) is being slowed down by the friction between the walls and the tea. Secondly, as the tea is stirred, the surface of the tea becomes concave with a distinct dip in the centre of the swirling tea. The result of all this is that a secondary rotation is set-up where the tea flows down the sides of the cup, along the bottom and then back up in the centre and once more to the sides (have a look at the diagram, some things are easier with pictures). As they are carried along with the water, the tea leaves move towards the centre of the cup but then, being too heavy to rise again with the tea up to the centre of the cup, they stay on the bottom forming a circular patch of tea leaves.

adaptation from Einsteins paper
The secondary circular flow set up in a tea cup when it is stirred leads to a circular deposition of tea leaves (figure adapted from Einstein’s 1926 paper).

When you think about how water flows as it goes around a bend in a river, you could perhaps imagine a similar secondary flow being set up but this time from the inner edge of the bend to the outer edge and back down (so, like half a tea cup). As the water is going to be moving fastest at the outer edge, just before it plunges down towards the bottom of the river in this secondary cycle, any river erosion is going to be most noticeable on the outer edge of the bend.

It seems the effect is also used in beer brewing in order to introduce a greater concentration of hops into the brew, and to separate different types of blood cell in blood tests. So this just leaves the poached eggs. How do you poach eggs? If you have a proper poacher perhaps you get neat eggs each time but for those of us without them, poached eggs tend to be a messy cooking project. But worry no longer! Just as tea leaves collect in the centre of a tea cup, so will the egg if you ensure that your pan of boiling water is swirling around the central axis before you put your egg in. Cooking helped by physics, perfect.

For reasons of full disclosure, I should emphasise that I have only recently found this suggestion for cooking eggs ‘theoretically’ and not yet tested it. So, if you were looking for reasons to drink loose tea, or wanted to poach an egg without a poacher, perhaps you could try Einstein’s little experiment and let me know how you got on, I’d love to hear your tea leaf readings and see your poached egg results.

Categories
Coffee cup science Coffee review Observations Science history Tea

Coffee innovations at MacIntyre, Angel

MacIntyre Coffee AngelOne motivation behind Bean Thinking is to explore those connections that can be found when we stop to really look around us. Whether your interest is in history, philosophy or science, something in a café will prompt a train of reflections that can lead to interesting and surprising thought journeys. This is surely true for anybody in any café, if we just take the time to slow down. But, I admit a prejudice: while I had heard great things about the coffee in MacIntyre, when I had glanced in from the bus window, I saw the scaffolding seating arrangements and wooden surfaces that can be a type of design found in many new cafés. So I worried. Was it going to be hard to ‘see the connections’ in MacIntyre? Would I end up with a great coffee but a challenge to my assumptions about the ubiquity of connectivity?

Fortunately, I needn’t have worried. The two lovely coffees that I have enjoyed at MacIntyre gave me plenty of time to really savour both the coffee and my surroundings and I was wrong in my assumptions from the bus window, connections really are everywhere. The café itself was a delightful find. Watching other customers while drinking my long black, it seemed that everyone was greeted by a cheery “hello”. Many people were clearly regulars, which is perhaps unsurprising for a friendly café with good coffee in a busy area. The scaffolding and wooden seating also works in the space at MacIntyre, giving a strangely relaxing feel to the café. The café itself is rather narrow, with the seating on one side and pastries/ordering queue on the other. Tap water was delivered with the coffee, without my needing to have asked for it.

Plant, light, scaffolding at McIntyre's Angel
Good scaffolding also has good connections.
Plant and light at MacIntyre.

MacIntyre may also be a great spot if you are into people watching. Amidst the general busy-ness, I could eavesdrop on conversations about the latest coffee news and the rise of artificial intelligence (these were two separate conversations!). Perhaps the conversations were particularly noticeable owing to the acoustics of the wooden walls and the narrow, small space of the café. At various points around the café, plants hung from the scaffolding. Some of the plants were spot-lit, which caused me to wonder whether the light that the plants were receiving was optimal for photosynthesis. The menu was projected onto the rear wall of the café, which was also decorated with hexagons, an immediate connection to graphene.

But then, in my coffee cup, the significant crema on the coffee showed evidence of amazing thermal convective motion together with turbulence. The coffee itself was very sweet with nutty overtones but the movements of the crema reminded me of cloud formation in thunderstorms. Although thunderstorms didn’t make it to the thought train of MacIntyre, another form of surface motion suggested a connection to another, unusual, feature of this café. You see, MacIntyre is a cashless business, no cash is accepted even if you’re only buying a long black. Most customers on my visit paid with their contactless cards.

The idea of a cashless society is one that has obvious advantages for both the business and the government/economy (whether it has such obvious advantages for the consumer I will leave as a point to be debated). While some countries are attempting to move to a more cashless economy, for a business to be entirely cashless is somewhat innovative. Even though MacIntyre is not the only café to go cashless (Browns of Brockley is similarly cash free), it has to be one of the first cafés to do so.

Coffee at MacIntyre Angel
Coffee and water on wood at MacIntyre Coffee. Could you increase the returns on your investments by understanding the movements on the surface of a cup of coffee?

What is the connection between this and the surface movement on my coffee? Well, it is not just at MacIntyre that a café has supported an innovation that has (or may) change our economy. Just over three hundred years ago, Jonathan’s Coffee House in Exchange Alley was a place of similar innovation, though there it was a customer rather than the coffee house itself that gave the change.

It was at Jonathan’s in 1698 that John Castaing published a paper twice a week detailing the latest stock prices titled “The course of the exchange and other things”. Recognised now as the origin of the London Stock Exchange, how stocks are priced and how their prices vary with time are subject to intense mathematical modelling. Although now, these models can be extraordinarily complex, the base of many of them share a mathematical model with the movements on the surface of your coffee cup, Brownian Motion.

Jonathan's coffee house plaque
The site of Jonathan’s in Exchange Alley. Seen while on a Coffee House tour last year.

Brownian motion is the phenomenon in which small particles of dust, or coffee grains on the surface of your coffee move in a random way as a result of collisions between the particles and the molecules in the liquid. First described in detail by a botanist, Robert Brown in 1827, the experimental evidence in favour of the molecular-collision explanation of Brownian motion came in 1910 with Jean Perrin’s careful experiments (that have featured in The Daily Grind previously). The maths behind the explanation relies on the idea of the ‘random walk‘ in which each dust particle is ‘kicked’ in a random direction by the molecules in the coffee, the consequent motion being frequently described with reference to a drunkard attempting to get home after leaving the pub. However, as this concept of the ‘random walk’ was being developed for molecules in a liquid, it was simultaneously being developed to model the movements of stock prices by the mathematician Louis Bachelier. Bachelier’s model of stock prices turned out to be the same as the model of Brownian motion, but both developed independently.

As yet, it is unclear (to me at least) whether there is a link between cashless payments and some of the maths in your coffee cup but, MacIntyre would be a great place to contemplate this as you sip your brew. Never succumb to prejudices, on which note please do let me know what you think of cashless payments, a great convenience or an invasion of privacy?

MacIntyre can be found at 428 St John St, EC1V 4NJ.

Categories
Coffee review Coffee Roasters Observations Science history Tea

Good vibrations at Vagabond, Highbury

black coffee, Vagabond, Highbury
A good start to the day. Coffee at Vagabond.

A long black, flat white (with soya milk) and a tea. Yes, you could say we spent a fair while at Vagabond in Highbury the other week. It was a lovely space to catch up with an old friend again. There were plenty of comfortable seats and the staff were definitely friendly, supplying us with coffee and space to chat for a while. The coffee was good (Vagabond are roasters as well as a café) with batch brew and Aeropress/drip on offer together with the usual selection of coffees and other drinks. Tasting notes were on a black board behind the counter while on the wall, also behind the counter, was a drawing of a tongue taste map. While the science of this has been disputed, it does serve as a reminder for us to sit back and properly appreciate – and taste – what we are drinking.

Above the espresso machine was a long rectangular sign that said “coffee in progress”, suspended by four cables, one at each corner. Coffee orders were placed onto this sign allowing the baristas to keep track of who ordered which drink. Given how busy this café occasionally got (and we weren’t even there for lunch), it seems that this is a very handy system. Each time an order was placed on the sign, the whole sign oscillated, rather like a rigid trampoline. Even if you had not seen the note placed on the sign by the barista, you would get a clue, a piece of evidence, that something had just happened by the vibrations long afterwards. Perhaps you may say that the sign was some sort of “order-detector”.

order detector oscillation espresso machine
The “order-detector”: sign at Vagabond in Highbury

Or at least, that is what you may say if you were thinking about the LIGO (Laser Interferometer Gravitational waves Observatory) detectors that, back in 2015, detected the gravitational waves produced by two merging black holes between 700 million and 1.6 billion light years away. Not only do these detectors have similarities to the order-detector sign at Vagabond, the beauty of the LIGO detector is that you can start to understand how it works by staring into your coffee. The LIGO experiment consists of two detectors. Each LIGO detector is an L shaped vacuum tube (4km long) with a mirror at each ‘end’. A laser beam is split between the two legs and reflected back by mirrors at the end of each L. When the reflected laser beams return back to the detector at the corner of the ‘L’, how they interact with each other is dependent on the exact distance that each laser beam has travelled between the mirror and the detector. Think about the bubbles on the surface of your coffee. These colourful bubbles appear as different colours depending on the thickness of the bubble ‘skin’. You may remember being taught that, exactly as with oil slicks on water, it was about the constructive and destructive interference of the light waves. As each ‘colour’ has a different wavelength, the colours that destructively interfere change with the thickness of the bubble skin. You can determine the thickness of the bubble by the colour it appears.

LIGO photo
An aerial photo of the LIGO detector at Hanford. The mirrors are at the ends of the tubes going away from the main building. Image courtesy of Caltech/MIT/LIGO Laboratory

In the LIGO experiment, there is only one wavelength because the light is coming from a laser. So whether the detector registers an intense laser beam or the absence of one, depends on whether those two beams coming back from the mirrors interfere constructively, or destructively. (A deeper description of the technique of “interferometry” can be found here). As the gravitational waves emanating from the collision of the black holes encountered the mirrors at the ends of the L’s in LIGO, so each mirror wobbled a little. This small wobble was enough to change the intensity of the laser light received by the detector and so reveal that the mirrors had moved just that little bit. In fact, the detectors are so sensitive that they can detect if the mirrors move by less than the diameter of a single proton. Given that this is a sub-atomic distance, I don’t think I can even start to relate it to the size of an espresso grind, even a Turkish coffee grind is millions (billions) of times larger than the amount that these mirrors moved. Yet this is what was detected a couple of years ago in the now famous announcement that gravitational waves had been detected and that Einstein’s predictions had been shown to be true.

Watching the “coffee in progress” sign oscillate at Vagabond, it is clear how much engineering has gone into isolating the mirrors at LIGO enough that they do not move as people walk by. Yet perhaps it is interesting that, nonetheless, one of the final refinements of isolating the mirrors from the vibrations of the earth involved changing the material for the cables that suspended them, just as with the sign at Vagabond. You can learn more about the engineering behind this incredible feat of detection in the video here, or you can go to Vagabond, enjoy a lovely coffee and think about the physics of detection there.

Vagabond (Highbury) can be found at 105 Holloway Road, N7 8LT

If you would like to hear what the collision sounded like, follow the link here.

 

Categories
Coffee review General Observations Science history

Some perspective at Over Under, Earls Court

Over Under Coffee Earls Court
Follow the arrow! Over Under Coffee in Earls Court.

Whenever I’m heading somewhere that I haven’t been to for a while, I check the London’s Best Coffee app to see if any new cafés have popped up in the area since my last visit. So when I was in Earls Court recently, I was very happy to be alerted to a new café on the map with a review by Beanthereat.

Over Under Coffee is at 181A Earls Court Road but is tucked around the corner from the main road and so thank goodness for the helpful arrow (and the map which told me I should be on top of it). Once found, we ordered coffee and banana bread and took a table to sit down. The friendly staff behind the counter were quite confident of the ingredients in the banana bread as it is made locally by a lady in Fulham (whose name I have sadly forgotten). The coffee and banana bread formed a great combination for a mid-morning snack. Coffee is roasted by Assembly roasters over in Brixton and came with lovely interference patterns in the bubbles on the surface together with dancing white mists, which never fail to fascinate me.

On the table next to ours was a small Kilner jar for sugar and two succulent plants. The Kilner reminded me of the use of air valves in coffee packaging (which are non-recyclable plastic) and the interesting experiment by Roasting House coffee roasters to investigate whether they are actually needed for freshly roasted coffee (which you can read about here). However it was a picture above the table that prompted the thought-train for today’s Daily Grind. A charcoal sketch, the picture featured a tree in the foreground with a fence behind it. From a very early age we are taught how to represent 3D objects on a 2D sheet of paper, the idea of perspective seems ingrained on our minds. But how intuitive is it really?

perspective in coffee
A picture at Over Under. Note the smaller reflections of the (more distant) light fittings.

Although the ancient Greek artists could convey an idea of depth in their art, the development of a mathematical understanding of perspective only came with Filippo Brunelleschi (1377-1446), although a written account of the mathematics of perspective did not arrive until Leon Battista Alberti (1404-1472). Alberti’s method for drawing in perspective used not just a vanishing point, but an additional diagonal vanishing point in order to construct a sense of depth and an accurate depiction of perspective (a description of Alberti’s method is here). The development of the understanding of perspective during the Renaissance meant that for some paintings, the ‘viewing depth’ can actually be calculated, while other artworks managed to create optical illusions whereby objects would jump out at the viewer as if they are in 3D. Works such as Andrea Pozzo’s ceiling in the chiesa di Sant’Ignazio in which a flat ceiling appears magnificently domed. Or, closer to home,  Samuel van Hoogstraten’s work in the National Gallery in London in which the viewer looks through a peep hole to see the interior of a house complete with a dog that appears to be sitting up inside the painting. Such paintings required a knowledge of the mathematical rules behind the depiction of perspective. Isn’t it surprising that the understanding of these rules is so recent?

Over Under Earls Court
Coffee with bubbles showing interference patterns at Over Under Coffee

Another art work with an interesting use of perspective that will bring us, in some way, back to Over Under Coffee is Raphael’s fresco “School of Athens“. The two figures of Plato and Aristotle stand at the centre of a diverse group of philosophers including Socrates, Zoroaster, Euclid, Diogenes the Cynic and, possibly, an image of Hypatia of Alexandria. Although the use of perspective for the architecture draws your eye towards the centre of the picture, two spheres (held by Zoroaster and Ptolemy) on the right hand side of the picture are drawn as circles rather than ellipses. Spheres viewed from an angle should be represented as ellipses if drawn correctly according to the rules of perspective. Did Raphael make an error in perspective (that may work better for our eyes?) or is the degree to which these two spheres are distorted within the limits of the fresco brush and so not visible in the picture? An episode of Radio 4’s In Our Time discusses this picture at length including a deep conversation about the significance of Plato pointing upwards towards the heavens and Aristotle indicating towards the Earth. Plato’s wisdom and Aristotle’s knowledge, above and below, much like the weave logo that brings us back to Over Under Coffee.

Over Under Coffee can be found at 181A Earls Court Road, SW5 9RB.

 

 

Categories
Allergy friendly Coffee review General Observations Science history

Thinking space at Le Peche Mignon

Coffee in Le Peche Mignon, Highbury, Islington
Le Peche Mignon in Highbury, hidden down a side street.

It was a balmy February morning when I met an old friend at Le Péché Mignon on Ronalds Road near Highbury and Islington. I had first come across Le Péché Mignon a few months ago when I had had a lovely coffee (and a great cake, I remember the staff being very helpful to check the ingredients for my nut allergy) but too little time to properly think about the space. So, when the opportunity arose to meet a friend (who I have known since we were both 5 but haven’t seen for many years) near Islington, I jumped at the opportunity to meet there.

This small but delightful café seems to be very popular. Both the bench seat in the window (where I had sat last time) and the long, sharing-table in the middle of the café were practically full by the time we arrived in the mid-morning. Fortunately, there was plenty of space in the quiet garden at the back for us to catch up for a couple of hours (and a couple of coffees!). The coffee is roasted by Monmouth, the Americano was very well done and there were quite a selection of pastries and salads on offer. One wall of the café was lined with bottles of wine while Carambars were available to purchase next to the counter.

brick wall at Le Peche Mignon
A join between two brick walls at Le Peche Mignon. How exactly are bricks made and why are they made that way?

The garden behind the café had plenty of tables and, even though it was February, it was warm enough for us to sit comfortably outside. One of the walls of the garden was formed by two sets of brick walls that had a join between them. The appearance of a separation between the walls, together with the weather, reminded me of the crack and the imminent demise of the Larson C ice shelf. However as this was probably too close to recent posts about climate change, I started thinking about defect structures in crystals instead. While pondering this though, my thoughts turned to an entirely different subject matter, the unusual toilet at Le Péché Mignon.

Just as the toilets in our old primary school, the toilet at Le Péché Mignon is outside, in the garden. This got us reminiscing about our old primary school which, during winter, regularly closed when the outside toilets froze (hopefully not a problem for the toilets at Le Péché Mignon!). And while the school has undergone significant renovation since then, it does get you thinking about the history (and engineering/science) of toilets. While this may seem an unpleasant subject for, what is after all a café review, please do bear with me because thinking about toilets can lead to surprising connections. For example, a recent New Yorker article about confirmation bias featured quite a discussion on toilets. How? It seems that while people generally tend to think that they understand how a toilet flush works, when asked to explain it step by step, they suddenly become far less confident. Our knowledge is not so great as we tend to think it is.

cup of coffee in Le Peche Mignon
From coffee cups to aeroplanes, the hardness and porosity of materials depends on the temperature that the starting materials were ‘baked’ at.

Which brings me back to Le Péché Mignon. The issue of flushing toilets became a problem for London in the mid-nineteenth century when the introduction of the “water closet” increased the volume of water flowing into the rather inadequate sewage system (if you are interested in the history of the toilet you can click here). The great engineer Joseph Bazalgette (1819-91) was commissioned to design and build London’s sewer system in which a network of tunnels were built across the capital. Bazalgette’s northern branch lies about 5 minutes walk north of Le Péché Mignon and runs from Hampstead Heath to Old Ford in Stratford. A distance of just 9 miles (14.4 Km), this particular tunnel has a remarkably steep gradient dropping at least 4feet (1.2m) every mile (1.6 Km). Imagine water flowing down a plug hole. The turbulence and speed of the water (ahem) flowing down this ‘drain’ means that Bazalgette had to think very carefully about how he lined this particular tunnel. If he had used ordinary bricks, such as those that make up the wall around the café’s garden, they would have eroded quickly with the turbulent motion of the water. Consequently, Bazalgette specified Staffordshire Blue bricks¹ to line this tunnel. During the manufacturing process, Staffordshire Blue bricks are baked at very high temperature (and in a low oxygen atmosphere) making them particularly resistant to erosion and to water absorption. It should not surprise us that the hardness, brittleness and texture of materials should be affected by the temperature at which they are formed after all, great care is taken about the temperatures at which chocolate is melted and allowed to re-solidify. Indeed, a vast amount of research is done to understand how different materials (from ceramics to metals) respond under different heat treatments. This research is important for applications as diverse as the walls of sewer tunnels to the design of aeroplanes. And, of course, to the design of better coffee cups, a thought with which we can return to thinking about this great little café.

Le Péché Mignon can be found at 6 Roland’s Road, N5 1XH

¹”The Great Stink of London…” Stephen Halliday, Sutton, 1999

 

 

http://www.plumbing-geek.com/howdoesatoiletwork.html

http://www.baus.org.uk/museum/164/the_flush_toilet

Categories
Observations Science history Sustainability/environmental Tea

A language problem?

Bob Ward, Obama quote, climate change
The last generation: our urgent need to communicate effectively.

“The beverage was prepared by pushing water (at 94ºC and 1.0 MPa) through a pellet of coffee beans ground to an average of 10 – 100 μm diameter. The pellet had been compacted (“tamped”) using a variable pressure as described in ref [1]. Following a manual transfer of the cup to the table, the drink was consumed at a temperature of 55ºC. Fruity overtones were noted.”

Would you rush to try this coffee?

Last week I wrote about the effects of climate change on coffee and how climate scientists are trying to reach out and communicate more about the science behind global warming. But there was a crucial question left un-answered, just how do we communicate? Do we all speak the same language or is the dry impersonal prose of science a hindrance to discussion?

To start with the encouraging news. It turns out that scientists are a pretty trusted bunch. In a recent survey 79% of the British public trusted scientists to tell the truth (compared with 21% for politicians). Part of the problem for politicians may be the language that they tend to use, “if I am honest…”, “to be fair…” etc, are apparently statements that haemorrhage trust. These are not statements that you will hear made by scientists. The language of science is cold and dry, utterly devoid of the personal. So, coupled with the results of the survey, it is tempting to think that we should continue to use our cold and impersonal language when communicating things like climate change. It seems that this works.

Steam, scattering, colour
How would you describe your coffee? Do those who read your description read it in the sense that you wrote it?

Only we would be wrong, the language that we use is (apparently) not helping us to communicate and we need to change it (as the meeting was told in an impassioned talk by Bob Ward). An average scientific paper for example is designed to convey exactly what we did, how we did it and to eliminate any possible element of confusion. Ideally, we would write a scientific paper so that someone else could read it, understand precisely what we have done and repeat the experiment under very similar conditions. In this context, our dry language can work very well but does it work generally when communicating results more widely?

To see the problem, compare the (scientifically written) coffee review that started this article with an extract from a recent review of Silhouette Cheapside by Brian’s coffee spot:

“The coffee offering’s simple: there’s a single-origin espresso from Notes, a Brazilian Cachoeirinha during my visit. As an espresso this was gorgeous: fruity and complex, it rewarded me with every sip, holding its own right to the end. I also tried it as a flat white, which was very smooth and surprisingly different, the coffee and milk perfectly complimenting each other.”

A visit to Cheapside may be imminent.

So this is the problem, while the scientific language may convey accurately what was consumed, it can’t convey it fully. Language that communicates more generally includes details about how we feel: “gorgeous”, “rewarded me with every sip”, “surprisingly different”. The language used in Brian’s coffee spot in no way detracts from an accurate description of the espresso or the flat white. Arguably your idea of the drinks that Brian sampled at Silhouette is far better formed in your mind than the idea of the espresso described by the scientific-language description at the start of this post. Can we extend this reasoning to scientific descriptions of the science of climate change and its likely effects?

Earth from space, South America, coffee
Our common home.
The Blue Marble, Credit, NASA: Image created by Reto Stockli with the help of Alan Nelson, under the leadership of Fritz Hasler

Perhaps you could imagine yourself in the position of a climate scientist: your research is showing you that the planet that you live on is likely to suffer significant change as a result of something that we humans are doing but can also do something about. I would guess that you are likely to get quite worked up about it. Wouldn’t it come across better if scientists were to use some of that emotion in how they communicate? Wouldn’t it convey our meaning more effectively?

Immediately though we come up against this issue of trust. Does the cold and dry scientific language somehow better communicate that the argument is evidence based? In this line of reasoning, subjective descriptions would be ok for things like describing a good coffee but not ok for describing climate change. And yet I can’t help feel that even here there is a problem. The philosopher of science Michael Polanyi argued that “Fairness in discussion has been defined as an attempt at objectivity, i.e. preference for truth even at the expense in losing force of argument”. Our “preference for truth” must include the fact that we have an emotional investment in the argument. It is our planet that we are destroying. Indeed, attempts to hide this emotional investment may even lead others to suspect climate scientists of other, more nefarious, secondary motives (financial gain, global conspiracy). However there is an important caveat on Polanyi’s argument, he writes: “[f]airness and tolerance can hardly be maintained in a public contest unless its audience appreciates candour and moderation and can resist false oratory…”.

screenshot of tweet from Digitalnun
A thought provoking tweet from @Digitalnun – science communication goes both ways.

Which brings me to a last point. A recent tweet by Digitalnun posed a question on related lines: does careless reading or careless writing lead to more problems? What we write is not necessarily what people read and if we allow emotion to enter into the cold language of science then we may increase the likelihood of misinterpretation (whether deliberate or not). Will those who read our attempts to communicate science with full honesty be able to resist false oratory, twisting our words to imply a ‘war’ or financial interest? Which is more appropriate, to remain dispassionate and potentially unconvincing or to be more honest in our discussion at the possible expense of losing trust? It’s not a question which seems to have an easy answer. What do you think? Do scientists have a language problem? Would you trust a discussion on climate change more or less if you thought that the scientist actually cared about the planet too? Let me know, either in the comments below, on Facebook or on Twitter.

[1] is hyperlinked above but if you are in the habit of scrolling down to look at the references, you can find the article about tamping in “coffee research” published here.

The Polanyi quotes are from “Science, Faith and Society” by Michael Polanyi, University of Chicago Press, 1964 (2nd edition)

 

Categories
Coffee review Observations Science history slow Sustainability/environmental Tea

Seeing the light at Cable Co, Kensal Rise

coffee in Kensal Rise, Cable Co
Cable Co, coffee in Kensal Rise

It was fairly late on a February afternoon that we came upon Cable Co on Chamberlayne Road, (opposite Kensal Rise station). With a fairly ‘industrial’ type look, there are plenty of tables at the edge (and in the window) of the café at which to enjoy your coffee. There are also plenty of coffees on offer. Although I had an Americano, I noticed (too late) that pour-overs were available. Coffee is roasted by Climpson and Sons. As it was late in the day, the remaining cakes in the display case all looked to be nutty (or at least likely to be nutty) and so, sadly, I had to wait until I got home for my slice of cake. It was good coffee though, even without the cake, but in a bit of novelty the coffee came ‘deconstructed’, so I got to add the amount of water that I preferred, a nice touch.

Golden light from the setting sun streamed in through the windows (which is a navigation clue & tells you which side of the road this café is on). The effect of the Sun was to bathe the café in light and to silhouette our fellow coffee imbibers making the café take on a film-like atmosphere. The light had another effect though. The steam rising from both the jug of water and my espresso became far more visible than it would normally have been. I watched as the steam clouds formed vortices and turbulent patterns, one fluid (steam) moving through another (air). It was very difficult to catch this in a photograph, a fact that I took in support of my idea that it is impossible to catch the beautiful, beauty is necessarily transient (but my companion in these reviews took as evidence in favour of their idea that I really ought to use a “proper”, manual, camera and not my iPhone).

Steam, scattering, colour
Steam rising from hot water, seen at Cable Co, Kensal Rise

Still, those turbulent rising patterns of steam were visible and that implies that light was being scattered from the droplets of water in the steam. The size of the droplets influences the colour that we perceive when we view the steam clouds. If the clouds appear white, it is because the droplets that are scattering the sunlight have a diameter roughly equal to (or greater than) the wavelength of visible light. The wavelength of light varies between about 400 nm (violet) to 700 nm (red) which means that these water droplets have to be at least 700 nm across. To put this in perspective, the smallest particles of coffee in an espresso grind are about 10 μm diameter which is 14 x bigger than the droplets in the steam cloud.

Of course, how water droplets scatter light above a steaming coffee has implications for our understanding of why the clouds in the sky appear white (and why the sky is blue). Someone who did a lot of early work in understanding the way that light scattered off water droplets in air was John Tyndall (1820-1893). Tyndall was an experimentalist as well as a famous communicator of science. He regularly gave lectures at the Royal Institution that included demonstrations of the experiments that he himself was working on¹. One of these involved scattering light from water droplets (and therefore demonstrating why he thought the sky was blue).

Interior of Cable co
Light streaming into the cafe.

The idea is that sunlight scatters from water droplets differently depending on the diameter of the droplet. When the water droplets are approximately the diameter of the wavelength of red light, 700 nm, there is very little wavelength dependence to the light scattering. Practically this means that the droplets will appear white. If on the other hand, the droplets are much smaller than the wavelength of light, the light scattering starts to be wavelength dependent. So as the droplet gets smaller, blue light (short wavelength) gets scattered a lot by the droplets, while red light (long wavelength) is not scattered so much. This means that if you are looking at a cloud of steam formed by these small droplets at an angle between the sunlight and yourself (say, 90º), the cloud will appear to have a blue tinge. If on the other hand you look straight through the cloud at the sunlight coming in, it will have a red-hue because the blue light will have been scattered out of the cloud leaving only the red colours to come through.

The experiment can be easily demonstrated at home by using very dilute milk in water (see video here or further explanation here). If you put a few drops of milk in a glass of water and then look at the colour of the milky-water as a function of angle, you should see it change from red to blue as you move the glass relative to the light source. The connection with the blue sky seems clear, small particles (in-fact, they can be as small as molecules) scatter blue light preferentially and so, apart from at sunrise and sunset, the sky will appear blue. As Tyndall wrote:

“This experiment is representative, and it illustrates a general principle…. that particles of infinitesimal size, without any colour of their own, and irrespective of the optical properties exhibited by the substances in a massive state, are competent to produce the colour of the sky.”²

Cable Co is at 4 Bridge House, Chamberlayne Road, NW10 3NR

¹A Vision of Modern Science, John Tyndall and the role of the scientist in Victorian culture, U. DeYoung, Palgrage MacMillan, 2011

²Quoted in John Tyndall, Essays on a Natural Philosopher, Ed. WH. Brock, ND. McMillan, RC. Mollan, Royal Dublin Society, 1981

 

http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/blusky.html