Category: Coffee review

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Coffee cup science Coffee review General Science history

Is it a third?…. Treelogy, Paddington

Outside Treelogy on Eastbourne Terrace, Paddington. The topiary could suggest a series of strontium atoms lining up on top of each other.

Good coffee near a mainline train station? It’s often difficult to find a good spot to take time to enjoy a coffee if you only have about 30 minutes (or less) before your train. Fortunately for coffee lovers in London, both Kings Cross (/St Pancras) and Paddington have several very good speciality coffee places nearby. There’s the cafe in the Pilgrm hotel just across the road from Paddington on London St, but Treelogy is perhaps even closer, directly opposite the buildings that house the new Elizabeth Line on Eastbourne Terrace.

Treelogy appears to have opened in April 2023. There does not seem to be much information online about it apart from Trip Advisor reviews so, having approximately 50 minutes before we needed to catch a train, we decided to stop at this new cafe. The interior is very modern and open. The counter is in front of you on the left as you enter with plenty of seats in the window and along the wall, as befits a cafe that is also close to a station. The style of some of the seats in the cafe and the fact that it is going to attract people who are about to embark on journeys (or have just come off a journey) means that there are elements here that could remind you of the scene in Edward Hopper’s Nighthawks. The coffee appears to be roasted by Treelogy themselves. There was a wide selection of pastries and breakfast bagels arranged on the counter and so we ordered two coffees to stay, and a bagel for the train.

The “Real Time” clock by Maarten Baas in Paddington. How much do they pay that man to be there all day?

We intended to sit on the bench just outside the cafe with our coffees but nonetheless we were offered our coffee in ceramic cups which was a nice touch. Inside, there was plenty to notice: circular lights on the wall leading to the back of the cafe which resembled ship lighting. A coffee dictionary book (and a book by Martin Wolf) that could offer a good read or a thought train on the physics of finance and the (Brownian-motion) links to coffee. The travellers with their roller bags going in and out of the cafe, who are they and where are they going? Yet, moving outside and settling down, the oat milk flat white and long black were both a very enjoyable way to spend time with a coffee.

As we were ‘spending the time’ with the coffees, the hands of the “REAL TIME, Paddington” Maarten Baas clock were being re-drawn every minute. Installed back in 2021, this clock appears as if the time is being painted onto the clock face by a man who seems trapped inside the clock. Each minute he erases the minute hand before redrawing it into its new correct position. Literally marking the minutes before our train is due.

For a physicist waiting for a train, an immediate thought may occur: what does ‘Real time’ mean? Admittedly, this question fades into the background again as the man wanders around, points at something on the clock, adjusts his position and then gets ready to move the clock hand again. The art is distracting from the question. But the question keeps surfacing: what is a minute, what is a second, is time absolute? There is perhaps a diversion that could be made here to a more philosophical question about the nature of time and our perception of it but we only had one long black and one flat white, the physics may take longer than that anyway!

A closer view of the man in the clock as he is erasing the minute hand of the clock. The colour bands on the clock face are not really there but are the result of the projected video onto the clock face and the way that the camera images that.

The physics bit remains because you may remember hearing about Einstein’s twin paradox, a thought experiment arising out of an aspect of his theory of Special Relativity. Relativity in general in physics refers to moving ‘frames of reference’, a classic case is that of a person on a train relative to a person on a station platform. For the person on the train, they are stationary, with respect to the train carriage. If they bounce a ball on the floor of a carriage, the ball bounces straight back up at them. They do not experience themselves moving (apart from when the train is accelerating or braking) and instead to them it appears that the person standing on the station platform is moving, backwards at the speed of the train.

Ordinarily our brains will process this and recognise that it is we who are on the train that are moving and we identify the ‘rest frame’ (the frame that is not moving) with the station platform. However we may all have experienced the sensation when on a train in a station next to another train. As the guard whistle blows the train moves but we cannot immediately tell whether it is our train that moves or the train next to us. This is the essence of relativity: all reference frames move relative to each other. The frame that is genuinely at rest is the one we define so (even the station platform is moving relative to the Sun, we just don’t notice this movement of the Earth at all).

Einstein’s theory of special relativity arises out of the special case when one of the moving frames is travelling at close to the speed of light, c. As the speed of light in a vacuum is constant, what would happen if someone travelling in a car at a speed just less than c looked at themselves in the rear view mirror? Einstein’s answer was that they would see themselves as anyone would because, relative to the reference frame of the car, the speed of light is still constant, it is still c. However an observer outside the car looking at the car and the person looking at themselves in the mirror also measures the speed of light as c, not nearly 2c (the speed of light plus the speed of the car). The speed of light in a vacuum is constant!

The explanation for this apparent problem is that our perception of time (and of distance) is not the same at different speeds. A person moving at a fast speed (relative to a person defined at rest) would have a wrist watch that was slow, relative to the person at rest – moving clocks go slow. This is the origin of the twin paradox which is that if one of a pair of twins travels away from Earth at close to the speed of light and returns, they will return younger than their twin who remained ‘at rest’ on Earth (but not relative to the twin who travelled who considered themselves at rest too so their earth bound twin should, to them, be younger).

Topiary at the entrance to Treelogy. The atomic clocks used in the study described in the text used super cold strontium ions positioned just above each other.

The solution of the twin paradox comes with Einstein’s second theory of relativity: General relativity.  Special relativity only concerns the case when different frames of reference move at constant relative velocity to each other. General relativity extends the case to accelerating frames and gravity. In order to meet again, the twin in the space ship had to turn around (decelerate and accelerate again). This changes the situation from the case expected purely from special relativity. There is a lot of experimental evidence for both special and general relativity, but recently one test of general relativity tested the idea on a very small scale.

The theory of general relativity postulates that it is not just moving clocks that go slower. Clocks in strong gravitational fields will also run more slowly. The extreme example of this would be the event horizon of a black hole, but even on Earth, a clock closer to the centre of the Earth will tick more slowly than one that is further away. Remarkably this prediction has recently been verified using extremely accurate clocks by measuring time using atoms spaced just 1 mm apart. The ‘clocks’ of the atoms 1 mm lower moved slower than the clocks of the atoms 1 mm above. Absolutely astonishing! And yet absolutely expected because one remarkable and weird feature about physics is that it seems to be universally applicable: what happens at the event horizon of a black hole shares the same physics as what happens in conditions far less extreme, conditions found in a coffee cup.

The Real Time clock is 7.8m above the pavement where I was enjoying my coffee. These experiments mean that I can be confident that the clock is going very slightly faster than the time I experience sitting on the bench. However, I shouldn’t use this thought to justify enjoying my coffee much longer and thereby miss the train! It seems that our trains aren’t quite so precise as the deviations implied by the theory of General Relativity. It is still necessary to get through the barriers with several minutes to spare. Treelogy, and the clock man, will have to wait for a return visit.

Treelogy is at 48 Eastbourne Terrace, W2 6LG

More about Einstein’s theories of relativity can be found here or in a good book in a library.

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Coffee review Coffee Roasters Observations Science history slow Tea

HR Higgins, Duke Street

Interior of HR Higgins cafe
The view of H.R. Higgins (Coffee-man) from Duke Street. The Royal Warrant can be seen on the side of the wall.

Established over 80 years ago, HR Higgins in Mayfair’s Duke Street is somewhat of an institution. From the pavement, you can look into the cafe space in the basement below while the shop upstairs offers coffee beans and tea for retail. During the (earlier) mornings, coffee is also prepared for take-away at the entrance to the shop on the ground floor while the cafe downstairs is closed.

The first time I came here, it was only to buy beans. That time I tried the Rwandan Women’s cooperative coffee and was impressed by the scales used to weigh out my 250g: a proper mechanical scale set complete with weights. The second time I tried it, again I only had time to purchase beans but I determined that the next time I would definitely try the cafe downstairs because if there was so much physics to appreciate upstairs with the scales and the decor, how much more would there be downstairs. And so, I arrived one morning at 8.30am having checked the opening hours and the cafe downstairs was… closed. It turns out that although the shop is open, and although take-away coffee is served from the front of the shop, the cafe only opens much later at 10am (on weekdays).

Inside an empty cafe.
Inside an empty cafe, downstairs at Higgins. The clock on the wall is a throw back to the ’70s while the mosaic tiling on the floor is particularly mesmerising. What strikes you?

However, what was an initial disappointment turned into a great opportunity as I was able to have a proper look around, completely on my own, while the man upstairs prepared my V60. Having no intention of actually ‘taking-away’ the take-away, when I came back upstairs (and had another look at the scales and tins of coffee at the back of the store) I went outside to the “H.R.Higgins” bench to sit and enjoy my coffee and the surroundings. There were a few pastries that were also available for take-away but this time I just took my coffee and sat down.

The coffee was really good. I had been given a choice of two coffees for the V60 and went for the Honduran as it was recommended as being particularly good for the V60 brew method. It was packed with flavour notes and character as it cooled while I sat on the bench. The bench offered a view of city life. The busy cafe next-door to my left; the old sign “Duke Street, W”* on the wall opposite; the imposing “Brown Hart Gardens” which is above an early 2oth century electrical substation just to my right and of course, the cafe itself in the basement visible behind me. The bench was also a good spot for people watching. Many people, with many characters, walked past (or got their coffee in Higgins and then walked past). I thought perhaps that I even saw George Osborne** wandering by but decided to let my mind wander to think about the physics instead.

Of course there was a lot to ponder. The nature of scales and the definition of the kilogram had been an obvious starting point but the reflection of the cafe name in the window opposite me provided further directions of thought. The patterns of the tiling in the cafe could provide several avenues of thinking while the history involved with the establishment of this establishment would have prompted a significant diversion. Finally, the antique bike standing next to the bench took me on the thought-journey that occupied the rest of the time I spent on the bench and enabled me to keep my phone left solely for taking photographs.

An old bike with flowers where a delivery box used to be.
The H.R. Higgins bike. Complete with Brookes saddle and flowers for luggage, this bike gave plenty to ponder while enjoying a coffee.

Now used as a flower pot holder, this old bike looked as if it had been adapted from a delivery bicycle of a fair few years ago. The brakes were immediately attention grabbing. We have become used to the wires used to operate the brakes on modern bikes but these used firm metal rods to transfer the action on the brake levers on the handle bars down to the wheels. And then the wheels themselves had rubber tyres. Again, this is somewhat obvious and very familiar except the first bikes had iron wheels because rubber tyres had to be invented.

There is a potential diversion here to the story of rubber, which could almost be a cafe-chemistry review but we won’t go that way today. Nonetheless, it is worth pondering that rubber tyres are, just like coffee, a product with a varied history of globalisation, trade and colonisation. What enabled the bicycle wheel to evolve from cast iron to pneumatic tyres was the chemistry involved in the ‘vulcanization’ process invented by Goodyear that meant that the rubber no longer suffered from getting too soft at higher temperatures and too hard at lower temperatures. Anyway, that’s a digression.

Returning to the bicycle, a lot of physics is involved in cycling. Is it actually clear how any of us can balance on a bicycle? A short answer, and the one that is often off-handedly given, is that we can cycle because of “conservation of angular momentum”, but it turns out that it is a little more tricky than just that. A few years ago, a chemist decided to test the ideas put forward to explain how we balanced on a bicycle by building so-called “un-ridable” bicycles and found that he could actually ride some of them, thereby showing that some of our ideas on bicycle riding needed a little ‘tweaking’. The basic ideas of conservation of angular momentum were correct, but like many things, if you actually want to understand it, you need to go a bit deeper (and do a couple of experiments!).

As we move beyond the basic physics so we move to the technology of cycling and the improvements that are being made to competitive cycles (and their riders) to make them more aerodynamic. We have moved a long way from brakes using rods and delivery cycles. And yet, sometimes there are advantages to the old ways. Just as the scales at H.R. Higgins still work perfectly well with the balance and weights system, so new delivery bicycles are re-appearing in London, swapping polluting vans for cleaner-greener delivery vehicles. Just these ones no longer have metal rods for brakes and they perhaps have a pedal-assist electric motor.

Have you enjoyed a coffee at H.R. Higgins (or somewhere similar)? What did you notice that enabled you to put your mobile phone down and really think about your surroundings? Do let me know in the comments section here or via social media.

H. R. Higgins is at 79 Duke Street, Mayfair, W1K 5AS

*The single “W” on the sign (rather than the post code of the area “W1”) shows that the sign has been there since before the first World War when the London post code system was refined from the merely “W” to the W1, W2 etc. that we use now.

**George Osborne was the Chancellor of the Exchequer (finance minister for the UK government) from 2010 to 2016.

Categories
Coffee review General Observations Science history slow

By Jove, it’s Ditto, Kuala Lumpur

Ditto, KL
A sign above the five-foot-way alerts you to the cafe above. “Ditto” in Bukit Damansara, KL.

“Ditto” it turns out can represent a number of meanings. No longer merely a shorthand for saying ‘the same thing’, it is now a Pokemon character and a fantastically chilled cafe on the first floor of a row of shops on Jalan Kasah in Kuala Lumpur. Ditto, the cafe, moved to the Damansara site in October 2022 having previously been a pop-up style cafe in Petaling Jaya.

A small sign hanging from the ceiling of the ‘5 foot way’ advertises that you can find the cafe up a set of unassuming looking stairs between two shops. Climbing the stairs, you do not expect the door at the top to open into such a quiet, ambient and welcoming space. Opening the door to the air conditioned cafe, the counter is diagonally left. A couple of circular tables are on your immediate left while a table full of coffee beans and coffee related books lies to your right. We first arrived very shortly after the cafe opened at 10am and so we had the place to ourselves. The coffee menu is extensive. Coffees from roasters around the world are available to try either as espresso based drinks or V60. Obviously I went for the V60.

interior cafe, Ditto, KL
Inside Ditto. Potted plants are dotted around the inside of the cafe while you could also choose to sit at a seat looking out of the window.

The first coffee I tried was a Colombian from Netherlands based roaster Manhattan Coffee Roasters. Very well made and interesting as a coffee, I was convinced that this was somewhere I could enjoy a geisha on my second visit. Almost tea-like, this geisha cup was a bit subtle for me although I could appreciate the different flavour notes coming out. Other drinks were also available (Kombucha, chocolate based drinks etc), though the focus is very much on the coffee. With such an extensive coffee menu, there are many more coffees than I would be able to sample before returning to London. It’s definitely a place that you can return to again and again while still finding something new.

The coffee arrived in a jug together with a couple of cups and a card reminding me of the tasting notes of the coffee I had chosen (though the print was too small for me to be able to read without glasses!). The jug showed evidence of condensation around the rim reminiscent of the physics of dew and the greenhouse effect. Physics was apparent too in the title of a book on display with the retail coffee beans: “The physics of filter coffee”. Flicking through the book, it was clear that this was a very comprehensive guide to the physics of how to brew good coffee. Should this go on the Christmas book wish-list? Elsewhere books and magazines offered plenty to think about on issues about the architecture of cafes or the types of coffee to be found around the world.

Table that resembles the surface of Jupiter
One of the circular marble tables in Ditto. The way the rock has formed suggests a view of the planet Jupiter. An overhead light has formed a triangle reflected from the table’s surface.

This is definitely a space in which you can sit, enjoy a well made coffee and contemplate whatever thought train your mind decides to take you on. And yet, I would defy anyone to look at the circular table and not think “Jupiter”.

The tables are made of marble, the layers that made the first set of sedimentary rock (that is the basis of the metamorphic marble) are clearly visible as horizontal lines cutting through the entire circle of the table. They are the stripes of Jupiter. The colour too is similar to the images that we have seen either from telescopes or from the satellites that have flown by Jupiter since Pioneer 10 first flew by in 1973. Looking at the coffee on the table, we could find ourselves echoing the quote from one of the scientists involved in the latest fly-by probe (called “Juno”) describing the “incredibly beautiful” planet as “…an artist’s palette… almost like a van Gogh painting.”

We have been aware of the weather patterns that form these stripes, and in particular the “Great Red Spot” for hundreds of years. Yet it turns out that we still have a lot to learn about them. For example, the clouds in the band at the equator are moving eastwards, the stripes immediately north or south of those are moving westwards and then the wind pattern changes again with the latitude, eastward and westward as each stripe is formed. Then, every 4-9 years, depending on the latitude, the colours of the stripes change, a change that can be associated with brief but disruptive changes to the weather patterns. Shape shifting rather like the Pokemon character “Ditto” that is the inspiration for the name of the cafe.

Cassini portrait of Jupiter, copyright with NASA
Not a table! A view of the planet Jupiter taken by the Cassini mission in 2000. Photograph shared according to NASA image use policy.

Recent results from the Juno mission have revealed one of the things that could be underlying this shifting weather pattern: oscillations in the planet’s magnetic field. Juno, which has been measuring the magnetic field of Jupiter since it first started orbiting it in 2016 has revealed that the magnetic field strength is oscillating on a similar time scale to the changing patterns observed in the weather. Could this somehow be driving the weather that we see? Juno has also shown clearly a new feature in the magnetic field where the field lines are particularly intense, called the “Great Blue Spot”, this feature too may be oscillating spatially over the surface of the planet rather than rotating around it as the Great Red Spot seems to do.

Juno, the satellite, was named after Juno the Roman goddess who is the female counterpart of the Roman god Jupiter. Considered in some ways to be patron of women, there seems another link here to this women-run cafe. We may be tempted to think that we have fully explored this physics connection that has looped back to the space in which we are enjoying our drink. But there is one more connection between Jupiter and this cafe. The first probe to fly by Jupiter was Pioneer 10 in 1973. It was then that we first saw images of this planet close up. The first time we saw these stripes in such detail. The satellite was launched by NASA in 1972, the same year that this area of KL was being developed. Perhaps you could say 1972 was the same year this area of KL was ‘launched’. There truly are links and connections wherever we care to find them. When we slow down with our coffee and contemplate our surroundings while open to going on a thought-journey, we never know where we may end up.

Ditto Speciality Coffee Bar is at 128A Jalan Kasah, Bukit Damansara, 50490, Kuala Lumpur, Malaysia.

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Coffee review

Drawing a Blank?

Blank Street Coffee on the corner of Charlotte Street and Goodge Street.

In the summer of 2020, a new neighbourhood cafe started up in New York. Now, at the end of summer 2022, Blank Street coffee has over forty locations in the US with two in the UK and the ambition of 24 in the UK by the end of 2022. This is not your usual small coffee shop. Nor is its financing. After initially raising $7m from venture capitalist firms, a recent fundraising round raised a further $25m. It is worth asking: why? What is it about this chain of cafes that makes financiers value it at more than $98m?

I came across Blank St Coffee at 44 Charlotte St on the junction of Googe St by accident. After a good Penang Assam Laksa down the road at Laksa Mania, we were after a coffee and this cafe looked, at first sight, like a small neighbourhood cafe. Judging from headlines in the New York Times, this post is going to date very quickly and conceivably, in just a couple of months we are going to wonder how it was that we had never heard of Blank St. As we got closer, the merchandise visible through the window, and other aspects of the coffee shop which are harder to pin point, suggested that this was a coffee shop backed by quite a lot of finance. There are a few such cafes around and it is not always easy to discern what it is, exactly, that indicates that they are far from my usual focus on neighbourhood cafes. However, on this occasion, we were after a coffee and thought we’d give it a try.

We ordered an Americano and an oat milk hot chocolate. The coffee is roasted by Origin Roasters and all the coffee is served in disposable cups. As we were drinking ‘in’ (on the benches outside), I refused a lid for the cup which was a mistake as the Americano had been filled to the brim of the cup. Shortly after taking the coffee from the counter and stepping outside I found, experimentally, how easy it is to spill a black coffee (as opposed to say, an oat milk hot chocolate). The over-filled Americano turned out to be an interesting feature because I had naively attributed it to human error. As with much else at Blank Street, such impressions can be deceptive.

Over-filled Americano and oat milk hot chocolate with a lid. You can see which one spilled by the liquid around the bottom of the cup.

I’ll declare a bias here. I think society works best with human interactions and community. It is why I have focussed on reviewing small, locally run, community cafes in the past. Blank Street Coffee has a different ethos which is to make good coffee affordable. While this is not necessarily a bad aim (click here for a discussion on the pressures and ethics involved in coffee pricing in cafes), Blank Street has a particular approach to cost cutting. Firstly it rents smaller spaces for its cafes. It also automates much of the coffee preparation. The baristas no longer have to make the coffee, they just push a button and the coffee comes out of the machine. This makes the over-filled Americano odd because it is an automated, not a human process, have they really designed the Americano to fill to the brim?

Blank Street Coffee explains that the fact that the baristas just have to ‘push a button’ for the coffee means that they have more time available to chat with customers. This does not make sense to me. I like knowing that the barista knows coffee and knows (and cares) how to make a good coffee. I like the fact that the barista knows more about coffee than I do and so can talk to me about different coffees and issues within the coffee chain. I do not see that the baristas can have the same in depth understanding of coffee if they are only required to push a button to make it. Nor do I think that this will reliably produce a good coffee as the coffee dosing needs to be adjusted throughout the day by experienced baristas in order to keep the espresso flavour consistent. There is a similar problem in experimental physics. In order to get more results in a given time frame (such as overnight), many pieces of equipment are now automated. This starts off as a great idea but has the result that the experimenters lose familiarity with the electronics behind the computer interface. It is hard to troubleshoot when something goes wrong if you don’t have the feeling for what different bits of the equipment do to begin with. On a practical point with the cafes, baristas are needed now because they are expected. If the aim is to provide good coffee cheaply, what is to stop getting rid of the barista entirely and allowing the customer to press the button?

Opposite Blank Street a properly blank sign. What used to be written on this sign?

The coffee itself was ok. It was nice to get a drinkable cup of coffee in a space in central London where you could sit on a bench and people watch. And in terms of the physics aspect of a cafe-physics review, there was also an appropriate point to consider. Just opposite the cafe there was a space on the wall of the shops for a shop sign. It was a type of nineteenth century panel built into the shop fronts which would in the past have been painted with the name of the shop below. Only this one was, fittingly, blank. Not really a ghost sign, it was so ghostly as to have disappeared altogether, it was a blank space. The presence of the sign was announced by its absence. A similar absence is revealing in space; “in space, no one can hear you scream.” Does this suggest that space is a vacuum? For sound waves to propagate, and so for your scream to be audible, the sound needs to create a pressure wave within a substance, whether that substance is a solid or a gas. If a sound wave cannot propagate and we take the movie-tagline literally, it would mean there is no substance in space, it is a vacuum. Depending on where you measure it, this is nearly true. In interstellar space, there is approximately 1 atom per cubic centimetre compared with 3×10^19 atoms per cubic centimetre on Earth’s surface. In intergalactic space there are even fewer atoms in a given volume. Even in interstellar space though, there are small fluctuations in the density of atoms with some regions having what appears to be a bunching up of the atoms present into waves as the shock fronts of things like distant supernovae come through. The spacecraft Voyager 1, launched in 1977, crossed the boundary into interstellar space in 2012. Voyager continues to take measurements of what it encounters and is now being used to understand the density of interstellar space, partly by measuring these bunched up bits as they flow over the spacecraft.

Voyager measures the density of space, partly by revealing the very absence of measurements for the most part. Which brings us poetically back to the name: “Blank” Street coffee. It is announcing something by its very anonymity. This anonymity is continued even inside the cafe. Painted a shade of green which is fairly instagrammable but somehow generic, a copy of other Blank Streets elsewhere. The space offers plenty to think about: what does it mean to be empty? Do we value something purely by its economic cost? And what does it mean to be anonymous, or even a unique individual, if you order coffee using an App on your phone?

Coffee at Blank Street was an experience. It can prompt many reflections on society and on physics. Yet, there are issues in its apparent anonymity and generic layout. Two weeks after visiting Blank Street, I visited a small, local cafe where the community and the physics jumped out at me. Offered the choice of many generic ‘blanks’ or a few memorable cafes, which would you choose?

Blank Street Cafe can probably, by now, be found all over London but was reviewed at 44 Charlotte Street.

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Coffee review General Observations Science history slow Sustainability/environmental

Me time at Hétam

Iced chocolate at Hetam. The chocolate is sourced from Indonesia. At the time of visiting, drinks were only available in take-away cups, hopefully this will change as the cafe becomes more established and the pandemic restrictions that were in place at the time of visiting are eased.

In 2021, a new cafe opened up in Bangsar, Kuala Lumpur, Malaysia. Called Hetam, it is a cafe almost designed for the post-pandemic, Instagram age that we find ourselves living in. At the time of visiting, there was no ‘inside’ to this cafe, everything was outdoors: customer seating was outdoors, even the ordering and the counter were outdoors. Umbrellas provided some protection from the downpours as well as the hot sun that you can get in Kuala Lumpur. You order at a counter which is on the right of what looks like it used to be an ordinary house on the service road parallel to Jalan Maarof (between Lorong Maarof 5 and 6). The house is now the headquarters for the online section of Hetam and is where they package up their online sales. There are a small selection of edibles to the right of the cash till but the main focus is on the coffee, tea and chocolate. The coffee is roasted by Hetam. At the time of visiting, the coffee was a choice of either an Indonesian natural or a Brazilian washed coffee and available as any of the usual espresso based drinks. I found that the Indonesian worked better in the espresso but that when brewing with an Aeropress at home, the Brazilian came out on top. Various Japanese Genmaicha and Hojicha teas were available but each time, I focussed on the coffee. The chocolate also is sourced by Hetam mostly from Indonesia and is well worth trying.

The staff at Hetam were very friendly and knowledgable. When we first arrived, they talked us through checking-in using the MySejahtera (Covid-19) app when we didn’t have data on our phones (as of 1 May 2022, hopefully MySejahtera will be something you don’t need to use any more). This led to a conversation on the origins of Hetam and their hopes for the cafe for the future. We ordered a hot long black and an iced chocolate and took a seat in the side/back garden of the house. The space seems almost made for Instagram. Infact, perhaps it was. Carefully arranged bamboo adorns the sides of the garden. White pebbles form the floor while strategically placed bits of tree are scattered throughout the space leading to a certain, specific aesthetic. The first time that we enjoyed a coffee at Hetam, another couple were already there. As we sipped our coffee, the couple split into model and photographer and, with what appeared to be a well practised routine of recognisable Instagram poses, set about photographing each other against different backdrops. In subsequent visits, we enjoyed the place to ourselves.

The counter at Hetam is helpfully under a shelter, the other seats are mostly under umbrellas. You get a glimpse here of the ‘insta-ability’ of the cafe. Random dead logs form a counterpoint feature to the white pebbles of the seating area.

The name “Instagram” is apparently a derivation of a combination of “instant camera” and “telegram”. The idea being that a message is sent through an image acquired by an instant camera. The word camera is in turn derived (from both Latin and Greek) from the word for a chamber or a vault. Presumably this was a suitable name for the camera because early photographs were taken through a pin hole into a vaulted dark chamber. Which brings us into the realm of physics as the photograph is literally that which is written by light. Film cameras and even the old Polaroid instant cameras, could still, legitimately be said to take photographs. The light would fall onto a chemically active film and change it based on the exposure levels so that the image was written directly by the light. When it was developed, the negative would be the reverse of the places on the film ‘written’ by the photons of the light (for a description of the process and a recipe for developing film with coffee click here, opens as pdf). This is not true of the sort of “instant cameras” most would now use to upload an Instagram post. In the case of digital cameras, the photons of the light still activate a light sensitive electronic chip behind the camera lens, but much of the interpretation of the image is done using computer software. For example, many of the light sensitive cells in the camera are not colour sensitive, they are only sensitive to the number of photons that fall on them (the intensity of the light). Colour images are formed by considering neighbouring cells which each have a different coloured filter covering them. The relative intensity of the electronic response within each group of cells is then interpreted by the software as a different colour. At this point can it be said that the image is written by the light? The final image is a mixture of the light falling on the photoactive cells and the interpretation of that electrical data by the software in the phone or digital camera. The light directs the electrons within the device but does it write the image?

Table, pebbles and bamboo in the seating area of Hetam, KL.

There’s also the issue of what it means to have the image and to share it. The picture on the phone, the image shared through the screens, is a collection of data points that no one can hold. A photograph printed from film or even the negative is, in that sense, more tangible. In the case of the negative, what you hold is what was written by the photons, by the light, at the point at which the subject was seen. In either case though what does it mean to have, or even to share, that image? Erich Fromm in his book “To have or to be” contrasts a poem of Tennyson with a haiku of Basho*. In the former, Tennyson ‘plucks’ a flower out of a wall in order to study it. Basho in contrast looks “carefully” at the flower; paying attention to it but not possessing it. Fromm questions our mode of being, suggesting that Tennyson could be compared “to the Western scientist who seeks the truth by means of dismembering life.” Is this fair? Does our desire to possess an image, pluck a flower or to ‘capture’ a moment and thereby ‘keep’ it necessarily imply that we would seek truth by means of dismembering life?

Which may take us to a consideration of those dead tree branches on the gleaming stones. They appear like petrified wood, wood that has been preserved for years through a process of fossilisation. We cannot own such objects, they outlast us. If we photograph it we cannot keep that moment, what does it mean to us if we don’t look carefully at the instant but rather try to pluck it for posterity?

So finally back to Hetam. While it may be ideal for Instagram, and while it will definitely be worth a few good photo ‘captures’, the space is also ideal for contemplation. For sitting with a coffee, enjoying the moment, appreciating the surroundings, both aesthetic and people, and for being rather than having. A friendly, outdoor and relaxed cafe, what more could you want?

Hetam is on Jalaan Maarof just next to the Petronas petrol station on the service road to Jalan Maarof.

*”To have or to be” by Erich Fromm, Jonathan Cape publishers, 1976 (1978)

Categories
Coffee review Coffee Roasters Observations slow Uncategorized

In search of origins

Amaje coffee
Buriso Amaje Coffee from Ethiopia via Amoret Coffee in Notting Hill. The Jimma 74158 and 74160 varietals are selections from coffee grown in the wild.

It was a goat herder named Kaldi, so the story goes, who first noticed the effect of coffee beans on the the energy levels of his goats. After telling the local abbot of his observations, the monks at the nearby monastery realised that this drink could help them stay awake during prayer and so the reputation, and consumption, of coffee spread from Ethiopia and then throughout the world.

While the details may be questionable, there is evidence that the coffee plant originated in Ethiopia. Coffee still grows wild in parts of Ethiopia and the oldest varietals are also to be found there. And so, when I realised that my latest coffee was an Ethiopian Natural of varietal Jimma 74158 and 74160, roasted by Amoret coffee in Notting Hill, I thought, why not do a coffee-physics review rather than a cafe-physics review? For there are always surprising links to physics when you stop to think about them, whether you are in a cafe or sampling a new bag of beans.

This particular coffee was grown by Buriso Amaje in the Bensa District of the Sidama region of Ethiopia. The varietals were selections from the Jimma Research Centre from wild plants that showed resistance to coffee berry disease and were also high yielding. Grown at an altitude of 2050m, the naturally processed coffee came with tasting notes of “Blueberry muffin, white chocolate” and “rose petal” among others. Brewed through a V60, it is immediately clear it is a naturally processed coffee, the complex aroma of a rich natural released with the bloom. Indeed, the bloom was fantastically lively with the grounds rising up with the gas escaping beneath them in a manner reminiscent of bubbling porridge (but much more aromatic). And while I lack the evocative vocabulary of Amoret’s tasting notes, the fruity and sweet notes were obvious, with blueberry a clear descriptive term while I would also go for jasmine and a slight molasses taste. A lovely coffee.

Brewing it again with an Aeropress, the tasting notes were different. We could start to ponder how the brew method affects the flavour profile. But then we could go further, how would this coffee taste if brewed using the Ethiopian coffee ceremony? Which leads to further questions about altogether different origins. Where did this come from and how do our methods of experiencing something emphasise some aspects while reducing others? Ethiopia offers a rich thought current if we consider how things originated because it is not just known for its coffee, Ethiopia is also home to some of the world’s oldest gold mines. Today, one of the larger gold mines in Ethiopia lies just to the North West of where this coffee came from, while a similar distance to the south east is a region rich in tantalum and niobium. We need tantalum for the capacitors used in our electronic devices. In fact, there is most likely tantalum in the device you are using to read this. While niobium is used to strengthen steel and other materials as well as in the superconductors within MRI machines. Where do these materials come from?

The Crab Nebula is what remains of a supernova observed in 1054AD. Explosions like these are the source of elements such as iron. Image courtesy of Bill Schoening/NOAO/AURA/NSF

Within the coffee industry there has been a lot of work done to demonstrate the traceability of the coffee we drink. But we know much less about the elements that form the components of many of the electronic devices that we use every day. And while this leads us into many ethical issues (for example here, here and here), it can also prompt us to consider the question even more fundamentally: where does gold come from? Indeed, where do the elements such as carbon and oxygen that make coffee, ultimately, come from?

The lighter elements, (hydrogen, helium, lithium and some beryllium) are thought to have been made during the Big Bang at the start of our Universe. While elements up to iron, including the carbon that would be found in coffee, have been formed during nuclear fusion reactions within stars (with the more massive stars generating the heavier elements). Elements heavier than iron though cannot be generated through the nuclear fusion reactions within stars and so will have been formed during some form of catastrophic event such as a stellar explosion, a supernova. But there has recently been some discussion about exactly how the elements heavier than iron formed, elements such as the gold, tantalum and niobium mined in Ethiopia.

One theory is that these elements formed in the energies generated when two neutron stars (a type of super-dense and massive star) collide. So when the LIGO detector, detected gravitational waves that were the signature of a neutron star collision, many telescopes were immediately turned to the region of space from which the collision had been detected. What elements were being generated in the aftermath of the collision? Developing a model for the way that the elements formed in such collisions, a group of astronomers concluded that, neutron star collisions could account for practically all of these heavier elements in certain regions of space. But then, a second group of astronomers calculated how long it would take for neutron stars to collide which led to a problem: massive neutron stars take ages to form and don’t collide very often, could they really have happened often enough that we have the elements we see around us now? There is a third possibility, could it be that some of these elements have been formed in a type of supernova explosion that has been postulated but never yet observed? The discussion goes on.

coffee cup Populus
Where did it all come from? Plenty to ponder in the physics of coffee.

The upshot of this is that while we have an idea about the origin of the elements in that they are the result of the violent death of stars, we are a bit unclear about the exact details. Similarly to the story of Kaldi the goat herder and the origins of coffee, we have a good idea but have to fill in the bits that are missing (a slightly bigger problem for the coffee legend). None of this should stop us enjoying our brew though. What could be better than to sip and savour the coffee slowly while pondering the meaning, or origin, of life, the universe and everything? That is surely something that people have done throughout the ages, irrespective of the brew method that we use.

As cafes remain closed, this represents the beginning of a series of coffee-physics reviews. If you find a coffee with a particular physics connection, or are intrigued about what a connection could be, please do share it, either here in the comments section, on Twitter or on Facebook.

Categories
Coffee cup science Coffee review Science history Tea

Schrodinger’s Katsute (100), Angel

Katsute 100, tea in Islington
It was a sunny day when we visited Katsute100 in Angel, Islington

When Bean Thinking started, it was always going to be about coffee and yet, Katsute 100 is definitely a tea place. Not only that, but the idea was to see how the physics that we use to describe our universe is mirrored by the physics of the coffee and in a cafe, the physics of the every-day. On the other hand, the whole point of Schrodinger’s cat is to demonstrate how aspects of quantum mechanics are absolutely unlike our everyday experience: a cat both (and neither) dead and alive? And yet, without giving too much away, today’s cafe-physics review is absolutely this – a review of a tea house that features the famous thought experiment. How far Bean Thinking has moved!

Katsute 100 is a welcoming, and peaceful, Japanese tea place in Angel. With a full tea menu and some really great desserts, it is definitely a good place to spend half an hour, maybe more, watching the coming and going and exploring the tea. And there is certainly a lot of tea to explore, different tasting notes revealing themselves as the tea cools, the carefully placed tea pot and tray adding to the experience.

The shop itself is fairly narrow, decorated in sympathy with the Georgian age of the shop itself and with a view into a garden at the back. Japanese tea making equipment is displayed (and for sale) on the various wooden cabinets around the shop. My tea had been buttery (exactly as it had been described in the tasting notes) and the Ichigo Daifuku I had had with it was a fascinating exploration of texture. There were some Japanese art works on the wall and it was then that I saw my first one: a cat. Not a real one of course but one of several decorative cats that are, almost hiding, around the shop. The word “Katsute” has nothing to do with cats apparently meaning “once”, but nonetheless, a few cats do pop up here and there. And even where cats don’t pop up, there are drawers in the wooden cupboards that seem much like boxes, is there a cat there in the box? Is it dead, alive, both, neither? What does this even mean? And is it connected to Katsute, “once”, after all?

note the pouring slits on the teapot
Tea pot, tea cup and ichigo daifuku at Katsute 100

Looking carefully at my teapot, three grooves were carved into the spout allowing the tea to flow out. Each stream of complex flow interferes with the neighbouring stream to present an aesthetic of flowing liquid to match the sound and flavour of the tea. And of course it is reminiscent of an experiment that is key to the unfamiliarity of quantum physics: the double slit experiment.

When light (of a single wavelength, such as from a laser) is shone at a sheet with two holes in it, the light that has travelled through shows interference fringes and patterns. Indeed, it is one of the experiments that went to establishing the theory that light was a wave (and not, as Newton among others had thought, a stream of particles). The situation is quite different if you tried to pass particles through two slits, imagine a sieve with two holes and a stream of coffee beans travelling towards it, we’d expect each bean to go through one hole or the other, not both. In classical physics that’s what we would expect too and yet, when sub-atomic particles (such as electrons) were aimed at two slits and made to travel through them they interfered with each other, as if they were not particles but waves. But other experiments had shown conclusively that they were also particles and indeed, when each individually hit the detector it did so as a single spot, as a particle. Particles and waves? What was going on?

cupboards in Katsute 100
A lot of sake and a fair number of drawers. But what is behind each drawer and why is one missing?

In fact it was a result that had been predicted: Louis de Broglie had shown, theoretically in 1923, that all particles should have wave-like properties and simultaneously, that all waves should have particle-like properties. We should expect that under certain circumstances, light, electrons, neutrons etc, even atoms, should behave as particles and under certain other circumstances (such as the double slit experiment) as waves. But there was an important catch. The electron travelling through a double slit will behave as if it is a wave, passing through both slits and interfering with itself to produce the characteristic “diffraction pattern” of a wave but only if we do not try to look at it to see which slit it really passed through. If we try to detect which slit the particle has travelled through, we can indeed find that some of the electrons travel through one slit and some through the other but when we look at the resulting interference pattern it is gone! What we are left with is the (classically expected) pattern of two particles going through two slits exactly as if they had been very small coffee beans. (You can see a video of Jim Al-Khalili explaining this peculiar result here).

What is going on? To a certain extent, this question is part of the reason that quantum mechanics can seem so strange. We can’t really ask what is going on, or rather, if we ask, we cannot expect to get an answer! We can describe what happens and we can make predictions based on the mathematics that we use to describe the processes. Our technology and our understanding of physics has developed hugely because we can describe how things will behave. But we will stumble if we try to understand what is really going on behind these processes. As Feynman said in lectures he gave to physics undergraduates:

“We cannot make the mystery go away by ‘explaining’ how it works. We will just tell you how it works. In telling you how it works we will have told you about the basic peculiarities of all quantum mechanics.”§

And so things remain enigmatic. Questions that appear to show paradoxes such as the problem of Schrodinger’s cat* continue to puzzle and intrigue us. Is the cat dead or alive? Can the cat be both? Is the cat an observer and what role does the observer have in physical measurements? What does this imply for the fabric of reality? And is there a connection back to the name of this cafe, “once”?

You perhaps should not expect to find any answers in Katsute 100, but pondering these things with a good cup of tea may help advance your understanding. It will certainly help advance your mood if you are in need of some peaceful, thoughtful, time out.

Katsute 100 is at 100 Islington High St, N1 8EG

§ Feynman Lectures on Physics Volume III, 1965

*The story of Schrodinger’s cat is that a cat is placed in a box together with a small amount of radioactive source material. The box is then closed and we cannot see inside. The amount of radioactive material is such that in one hour it has a 50:50 chance of decay. If the material decays radioactively, it triggers the release of a vial of poisonous gas which would kill the cat. Our mathematical models of quantum mechanics suggest that, until it is measured, the radioactive material is in a ‘superposition of states’: it has both decayed and not decayed; the cat is both dead and alive. Only when we open the box after an hour and thereby measure the state of the radioactive material does the cat, at that point, ‘collapse’ into a state that is either dead or alive.

Categories
Coffee review Observations slow Tea

Rosie and Joe, St Giles churchyard

Coffee in a Wake Cup at Rosie & Joe in St Giles. The space rewards those who notice.

There is a long history of hospitality on the site of St Giles in the Fields stretching back far earlier than the Notes coffee barrow. But Rosie & Joe is a lovely iteration to that tradition. There’s a definite focus on tea at Rosie & Joe but the coffee is roasted by Square Mile and prepared on a La Marzocco machine. There is also a good selection of food to nibble on (as well as more food stalls nearby on weekday lunchtimes). And although it is a cart, there are a few seats and tables dotted around so it is easy to sit back and enjoy your coffee while the world races by.

St Giles High St is a very busy road and yet, sitting in the churchyard of St Giles is strangely peaceful. Despite the traffic and the occasional siren, it is one of those rare places in London that you can find the stillness to listen. A beautiful place to enjoy a coffee from an independent stall in fact! And if you have your own cup with you, there is even 10p off your coffee. The coffee was smooth and sweet, fruity but definitely a sweet and full bodied type of fruity cup. But why was it so peaceful? Was it merely that it was a lovely (but breezy) spring morning when I tried Rosie & Joe? Or was it that it is a small bit of nature in a built up environment? Both of these helped but I think it is also the way that the place rewards those who notice by offering more each time you look.
The ghost sign hidden behind the tree just outside the churchyard.

There’s the, perhaps slightly grim, history suggested by the fact that the ‘garden’ is significantly raised above the level of the pavement in parts. There’s the brickwork and stone walls of the church itself of course. The ‘ghost sign’ on a nearby building that is revealed to the coffee drinker by the fact that the tree between us and it has not yet got its summer leaves. And then the nod to the history of the site hinted at by the coffee cart itself: Since Matilda, wife of Henry I founded St Giles’ leprosy hospital on the site, a “cup of charity” was given to condemned prisoners as they made their way past St Giles on their way to their execution at Tyburn*. Very different now, but the tradition of refreshment for the traveller is continued.

But then a fire engine’s siren reminds you that you are in a cosmos, a universe filled with beautiful physics. You know whether the fire engine is approaching or has passed away from you from how the pitch of the sound changes as it goes past. The Doppler shift meaning that sound waves travelling towards you have a shorter wavelength (higher frequency, higher pitch) than those travelling away (longer wavelength, lower frequency, lower pitch). And part of the beauty of physics is that it is so universal; what works for sound also works for light. If an object emitting light is moving away from us, the light appears to have a longer wavelength (lower frequency, it is red-shifted) than if the same object were stationary or moving towards us where it would appear as if it emitted light with a shorter wavelength (higher frequency, blue shifted).

signboard at Rosie and Joe
Doesn’t a right imply a duty? There’s a lot that could be said about #supportindependent
So, similarly, if we were to look at the surface of a rotating planet and saw how the light reflected off that planet’s surface, the side of the planet that was rotating towards us would look ever so slightly bluer than the side rotating away from us which would look slightly redder. And if the planet’s surface was like Venus and obscured by clouds (rather like the ghost sign at Rosie & Joe will be obscured by leaves in a couple of months time) we could use the reflection of radio waves from the surface rather than visible light to see the same red-shift/blue-shift in the radio waves as the planet rotates**. In this way we could determine the direction of rotation of the planet and how fast it was rotating just as we get an indication of the speed of the fire engine from listening to the sound of the siren.

The siren takes us from a consideration of inner stillness to a recognition of the scale of the universe. Which is rather apt for a cafe in a churchyard, where the architecture of a church is often designed to be read symbolically, from the person to their place in the grand scheme of things***. One great thing about this particular cafe though was how much there was to see that cannot be included in this cafe-physics review for reasons of space. The location truly rewards those who pay attention to what they notice here. I can only recommend that you take some time out, take your re-usable cup and go to find some time to enjoy your coffee (or tea) in this quiet space in central London.

*The London Encyclopaedia, 3rd Edition, Weinreb et al., 2008

**Astronomy, the evolving universe, 6th Edition, Zeilik, 1991

***How to read a church, Taylor, 2003

Rosie and Joe can be found in St Giles in the Fields churchyard, Monday-Friday.

Categories
Coffee review General Observations

Semi skimmed at Full Fat, Balham

exterior of Full Fat Balham
The shopfront almost seemed to skinny for the name of this cafe.

Just around the corner from Balham tube station, on Chestnut Grove is a new (old) café, Full Fat. Although it has only been in its current location since September 2018, it was previously known as the Balham Kitchen and was apparently quite popular, not just because it was a friendly local café, but also because of the coffee and the chapatis.

We had chanced upon Full Fat while in Balham and took the opportunity for a chapati brunch. During our coffee break several customers came in and had a chat with the two people behind the counter. With coffee roasted by Workshop and an excellent range of homemade chapatis, along with friendly people, what is not to like? We enjoyed an Americano and an oat milk hot chocolate together with two chapatis. My egg chapati was perfectly done, just the right amount of pepper-to-egg balance. And the coffee was also very well made with plenty to think about just by gazing into it.

Although the café itself is quite small, there are three tables and several seats, enough to be able to ensure that you can probably perch somewhere to enjoy your coffee and chapati. There are even entertaining drawings on the walls of the café that make me wonder whether these are previous customers, immortalised on the walls enjoying a cup of coffee with their morning paper? Certainly they are a good reason to put down your smart phone and just soak in the atmosphere here.

pencil drawings in Full Fat
Pencil drawings at Full Fat Balham

Apart from the drawings, the other decoration in the café that caught my attention was behind another table: a striped piece of woodwork that was reminiscent of a type of cake served in Malaysia and Singapore, kueh lapis. It is a layered cake, the idea being that you peel each layer off to eat it, extending the enjoyment that you can get out of a cake. Although the layers peel easily, ordinarily the cake holds together as a cake, the layers do not glide over each other as if they are wholly separate, perhaps like chapatis stacked on top of each other. No, whether the cake works or not, as a kueh lapis, is down not just to the flavour, but also to the texture and to the way that each layer peels from the next, the subtle tug of one layer held, but not quite, by the last.

These interlayer or interface effects are often, ultimately, an atomic phenomenon. Just as when you drop a drip of coffee on the table, the thing that ultimately determines the shape of the droplet is the attraction between the molecules in the water and the atoms on the table surface*, so the stickiness of the cake has to be occurring, ultimately, at the atomic level.

Interface effects can be crucial in other solids too, not just coffee and cake. Consider sapphire. Sapphire has the molecular formula Al2O3. Ordinarily it is colourless and transparent, it becomes blue when impurities are added to it. But sapphire has another property which is that it is electrically insulating: a sapphire would not conduct any electricity if you tried to use it to connect to your light bulbs. This insulating behaviour is shared with another oxide, strontium titanate, SrTiO3, which is also a colourless and transparent material. Nothing of any interest there then. But, and this is the key thing, if you took a piece of strontium titanate and grew the sapphire on top of it, under certain growth conditions, this bilayer becomes extraordinarily electrically conducting, far better than many metals that you can think of. And it is because of the atomic effects that occur at the interface between the strontium titanate and the Al2O3.

Layering of wood at Full Fat
Can you see the layering on the wooden panel behind the table? Thought not, you’ll just have to visit Full Fat and see for yourself.

But then another example, a new finding that is perhaps more closely associated with coffee. When you take the semiconductor molybdenum ditelluride (MoTe2) and sandwich a thin layer of it between two sheets of graphene, some atomic-level interactions occur. In the case of MoTe2, the “band gap” of the semiconductor (which determines how it conducts electricity when light is shone on it) is altered by the van der Waals forces associated with the graphene layers: the interface effects are changing the way that the semiconductor reacts to light. Ordinarily if you shine a pulsed laser at such a semiconductor, the electrons† that get excited across the band gap are few enough that they behave as a gas within the semiconductor. This means that if you add more electrons (by pulsing the light on the semiconductor again), the density of the electron ‘gas’ will increase. What researchers have just shown is that for this 2D layer, if you shine very high powered lasers at the MoTe2 layer for a short length of time, so many electrons get excited that the semiconductor no longer behaves as if it contains an electron gas, but an electron ‘liquid’. A sort of droplet of electrons in the locality of the laser beam. And because of the way that the band structure had been affected by the interface layers, they managed to obtain this behaviour at room temperature. Although such liquids had been created before, the new thing about this result was that previously these experiments were usually done at very low (-269C) temperatures. Quite a temperature increase on previous results!

Droplets of an electron-hole excitation may seem a far step from the droplets of coffee that you could be enjoying at Full Fat. However, it is just a short hop for the imagination if you stopped to give it time to think. What will you notice next time you are in a café?

Full Fat is on Chestnut Grove, literally just around the corner from Balham tube station.

*Assuming that the table is flat. If the table is nanostructured, the structure itself can influence the ‘wettability’ of the table.

†Yes, and holes.

Categories
Coffee review General Observations slow Sustainability/environmental Tea

To stay or to go at Cafe from Crisis

coffee commercial St volcano
Cafe from Crisis on Commercial Street, E1. Notice the arches…

It was not what I had expected. Entering the door of the Cafe from Crisis, you go up a ramp with a bench running alongside it before the counter looms in front of you with a large café space opening up to your right (previously partially obscured from your view by the wall for the ramp). Perhaps it is fitting that my expectations were wrong. Many of us have ideas about the homeless (why they are homeless, what homelessness is etc) that may not match fully with the reality. And this café is, after all, in the head office of Crisis, a UK national charity working with the homeless and homelessness.

The coffee is roasted by Volcano and there are a large number of food options (including vegan and veggie) and cakes at the counter. A selection of keep cups are also arranged in a rack on the left of the counter, should you not have one yet. We ordered an Americano and tea (to stay) and took our numbered wooden spoon to the table so that they could find us. Although it was late lunchtime and busy, the drinks arrived fairly quickly with the coffee in a (Crisis themed?) red cup. Apparently serving coffee in red cups make us perceive the coffee as warmer than if it is served in a blue cup. Whether this is true or not, the warm brew was very welcome on this cold January day. The café is situated on a street corner which means that it has many windows, each topped with a shallow arch. The building looks fairly modern from the outside, but the arches were reminiscent of the way that older buildings can be dated by the window style, along with other features. The Cure played in the background which entertained my tea drinking companion but made me wonder about the ideas of Pythagoras on the psychological impacts of different sorts of music (and whether it affected the ability to find thought connections in a café).

plant in a coffee cup
It turns out there are many things to notice in this photo. From the bricks to the self-defence tactics of plants. But what about the nature of the home of the plant?

As we sat, enjoyed our drinks and looked around, we noticed that some plants had found a home in coffee cups placed on the tables around. Small plants in plastic pots (a nod to the anthropocene as pointed out by @lifelearner47 on twitter) were dotted around the café. Did they move from an espresso to a long black cup as they grew larger? Perhaps it was the spiky plant in one of the pots, but my mind immediately jumped to hermit crabs and their search for a new shell each time they grew a bit bigger. Marine hermit crabs  have been shown to be happy in any old discarded shell. Normally these are the ex-homes of gastropods that have, well, “moved on” would be a euphemism, but marine based hermit crabs have been known to make their shells out of all sorts of things including our plastic litter. Land based hermit crabs however are far more demanding and only move into shells that have been specially remodelled by earlier generations of hermit crabs for their own use. This means that land based hermit crabs have to develop a social awareness of other hermit crabs when they want to swap shells.

Apparently the interaction goes something like this: A group of hermit crabs come together in a small-ish area and begin to scope each other out. The loose collection becomes a cluster as the crabs explore whether one of the larger crabs can be evicted from its shell. As the process of eviction is about to occur, the remaining crabs (which can number quite a few, 10 or more) literally ‘line up’ in order of shell size so that, when the largest is evicted, each crab can move up to the next sized shell leaving the smallest, most undesirable shell on the seashore and the poor evicted crab, shell-less.

Several questions arise but one is, do the crabs make decisions, “to stay or to go” based on how advanced the eviction process is? So, say a crab wanders into an area with an unusually large number of crabs in it (perhaps 4) but the crabs are all lined up in a queue ready to swap into each others shells. Do the crabs coming into the area stick around for a long time or do they head off somewhere else? Or, conversely, what if they enter an area where there are more than the usual number of ‘colleagues’, but they are all scattered about, not yet ready to evict the largest crab. What would our incoming crab do then?

coffee red cup Crisis
What would you learn if you noticed the connections your mind was forming while enjoying a coffee?

These questions were addressed by a group working with the terrestrial hermit crabs of Costa Rica. By defining five cells on the beach, each with a different arrangement of (empty but inaccessible) shells that the incoming hermit crab may want, the researchers found that the incoming hermits were making some strikingly sensible decisions. When the crab came into a region of scattered shells (that the incomer mistook for fellow crabs owing to a trick with a combination of loctite glue and partially burying the empty shells that the researchers used to fool the incomers), the incomer tended to stick around, waiting for an opportunity to swap a shell. If the incomer came but saw that the queue of shells had already formed, it still stayed a bit longer in the region relative to a control area devoid of shells, but it did tend to leave it after some time, perhaps to look for new shells elsewhere. The researchers concluded that when the crab came into an area and thought it had a pretty good chance of inserting itself into a good queue position, it would stay in the area waiting for the eviction to occur and the shell swapping process to start. However when the crab came into an area where the queue had already formed, it was unlikely to be able to get a good position in the queue and so would investigate the situation for a bit before wandering off elsewhere in the search of a new shell in a different area.

Does this have any relevance to a café trying to do a bit to address the problems of homelessness and the homeless in our city and country? I will leave that to each reader to ponder. However, it was a great opportunity to learn something new about our world, which only happened because I stopped to notice something in a café and then wondered how hermit crabs get their homes. It’s always good to slow down and notice things. What will you see next?

Cafe from Crisis (London) is at 64 Commercial Street, E1 6LT.