Brown – Bean Thinking

One 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.

V60 from Leyas — Could your coffee be used to power a perpetual motion machine?

There can be no such thing as a perpetual motion machine right? Yet less than two hundred years ago it seemed possible that there could be. Not just that, the source of this perpetual motion machine was in your coffee cup. How would you explain Brownian motion?

Brownian motion is the random movement of small bits of dust or coffee/tea particles on the surface of your brew. To see it, you may have to use a microscope though you should take care not to confuse Brownian motion with motion caused by convection currents. There will be Brownian movement even a long time after the coffee has got cold. What causes this continuous movement? When he observed it for the first time in 1827, Robert Brown (1773-1858) had thought it was to do with a ‘life force’. He had been observing pollen suspended in water and noticed that the pollen kept moving under his microscope lens. In 1827, this was a very reasonable explanation, after all, weren’t several people looking for a motion, a force, that gave life?

Sphinx, Brownian motion — Brown used some dust from the Sphinx (shown here with the Great Pyramid) to show that ‘Brownian’ motion could occur in inorganic materials. Postcard image © Trustees of the British Museum

So, he checked if he saw the effect in pollen that was one hundred years old (he did) and then in truly inorganic matter, he looked at the dust from a fragment of the Sphinx. Again he saw the dust fragment move in the water. He had therefore shown that it was not associated with a life force but was something that happened for every small particle suspended in a liquid. What was driving it?

Without knowing what caused it, some people in the nineteenth century had already suggested a device to exploit it, using tiny levers to carry the energy from this continuous motion into devices. Others insisted on finding out what was causing the motion but it was here that the physics of the day hit a philosophical problem. It was proposed that molecules in the water could be hitting the dust on the surface and moving the dust in seemingly random directions. And yet there is a problem with this explanation. At that time there was no way of seeing or measuring molecules. How could physics postulate a theory – or suggest a reality – that could not be tested?

Nasa, Norway, coastline, fratal — How long is a section of coastline? Coastlines can be described as fractal like. Mathematics that grew out of studying random walks and Brownian motion. Image credit NASA Visible Earth/Jeff Schmaltz

An answer came one hundred years ago in a paper published by Albert Einstein (1879-1955) in 1905. In it he made some mathematical predictions that, for the first time, allowed the theory (that it was molecules causing Brownian motion) to be tested by experiment. Jean Perrin (1870-1942) of the Sorbonne, Paris, was the experimentalist who, by careful observation of droplets of water containing a pigment used by water colour artists, provided evidence for Einstein’s theory of Brownian motion. The experiment was so important that Perrin later wrote “.. the molecular kinetic theory of Brownian movement has been verified to such a point in all its consequences that, whatever prepossession may exist against Atomism, it becomes difficult to reject the theory.”

The consequences for our world have been profound. The mathematics that describes Brownian motion is that which we use as the basis to predict the movements of the stock exchange. Extensions of the mathematics have been used to develop new areas of mathematics such as fractals. Even art has grasped the theory of Brownian motion, the Anthony Gormley sculpture “Quantum Cloud” is based on mathematics describing Brownian motion. Everywhere you look there are phenomena described by the movements in your coffee cup. What we have yet to do is find that perpetual motion machine.