allergy friendly – Bean Thinking

Squaring the circle at Omotesando Koffee, Fitzrovia

There was a lot of excitement late last year (2018) as the London branch of Omotesando Koffee opened just off Oxford Street. I watched as there were visits by Brian’s Coffee Spot, and Bex’s Double Skinny Macchiato and others, thinking that soon, I too would pop along. After all, it is a place that celebrates pour overs in central London. And yet, I went for the first time two weeks ago while meeting Sadiq of Amoret Coffee to discuss details of the first coffee and science evening being hosted in the Notting Hill branch of Amoret on the 11 June (more details and sign up page here).

On that first occasion, I had enjoyed a Rwandan by pourover and took in the minimalism and cubist geometry of the cafe but largely was too involved in discussing details of the event to think about the connections that the space prompted. And so a second visit was arranged. Again I found that the fold out chairs underneath the bench tables were a little too tall for me (though on the second occasion I didn’t fall off) but it did mean that, although I had a prime seat in front of the bar where they were preparing my pour over (a Burundi from guest roaster La Cabra), it was not easy to turn around to watch. It was however great to find that the cake menu at the order point at the front of the cafe clearly listed all the allergens in each of the cakes and so I was able to confidently enjoy a vegan banana cake with the coffee.

Omotesando Koffee, brownie with square revealed — Cubes and squares were a recurring theme inside the cafe

Omotesando offers a challenging space for a website built on the premise that any cafe offers an opportunity to explore connections to the wider world of physics if you just slow down, take in your surroundings and notice them. It is a space that seems to revel in minimalism. Most of the space is a fairly light coloured, mostly uniform wood. The bar is framed with a cube, a shape that seems to crop up all around Omotesando, even in some of the cakes. The fold out stools (circular) are made of the same colour of wood as the rest of the majority of the cafe (though there are a couple of exceptions to this which hint at the carpentry). Perhaps the idea is that we should focus on the coffee rather than the environment. And maybe that is where your mind enjoys wandering, but another thought suggested itself to my mind.

Sitting on the stool facing the window, wishing that I could turn around to watch the pour over being poured while remaining comfortable (there is a foot rest when facing forward), it struck me that sitting right in front of the bar did not help me when I wanted to use the glass of the window as a mirror to the inside of the cafe. The glass was perfectly transparent to my eye and reflected very little of the light behind me. The fact that the side of the (La Marzocco) espresso machine was transparent rather than metallic and revealed the pipework and wiring that enabled great espressos to be prepared (we also enjoyed an iced latte) briefly led me to consider why some materials are transparent and others not (and also how transparency varies as the frequency of light changes).

Banana bread and coffee with IoP bag — My pour over coffee, a banana bread and my IoP re-useable bag sitting on the table at Omotesando, Fitzrovia, London

But as I reflected further, I could see in my mind’s eye, the viewpoint of a deep sea diver looking up from the sea bed towards the sky. A circle of light, “Snell’s Window” opening above them. You can see images of Snell’s window where divers are framed by the effect in the photograph here. The effect is caused by the refraction of the light as it enters the water. Just as a straw (paper of course) appears bent as you view it through the glass of water, so light entering the sea will be bent by an amount given by Snell’s law. Even light entering at a grazing incidence will be refracted towards the ‘normal’ (the line perpendicular to the sea-air interface) and so if you work through the maths (there’s a good description here), you find that you will only see light from a cone of about 100 degrees around your view point.

Coffee reflections — What would you reflect on?

But although Otomesando has an entirely glass frontage, you do not feel you are in a gold fish bowl, nor can you only see a small window outside. The wide window instead offering plenty of opportunity for watching the office workers and builders scurry about outside. And, on writing this and looking through my photos of the cafe, I noticed that my photographs of the front of the cafe and of a coffee inside were both taken at shallow angles showing the reflections from the surface of the window and the coffee rather than the interior. An effect almost opposite to that of the deep sea diver. Omotesando Koffee offers a space where each cup offers further opportunities for reflection: more time for noticing the physics of the everyday. A great place therefore to spend some time thinking about, as well as enjoying, your coffee.

Omotesando is at 8 Newman Street, W1T 1PB

Focussing the sound at Spike and Earl

soya latte ginger beer — Soya latte and a ginger beer at Spike and Earl.

A few months ago, news came that the coffee roasting company Old Spike had opened a new café, Spike and Earl, down in Camberwell. Operating on similar principles to Old Spike, Spike and Earl aims to serve excellent coffee (and food and cocktails) with a social conscience. By employing those who have previously been homeless, Spike and Earl offers an employment (and training) route for people who may not easily otherwise have the opportunity. So although Camberwell is a bit of a trek, I was looking forward to trying this new place. As it was a late afternoon in November and the menu suggested that the dairy alternatives were only soya or oat, I decided to try a soya latte. (For any reader with a nut allergy, the current fashion of using almond milk means that you should always ask first if your cappuccino contains nuts). The baristas were friendly and confident in assuring me that they do not use almond milk (no danger of nut-cross contamination) but that their brownies did contain nuts (so I sadly had to pass on the brownie opportunity). My partner in these café reviews opted for a ginger beer.

There were a series of high tables with stools on the left hand side of the café. Presumably many people can therefore be accommodated when it gets crowded. However, at the time of our visit, it was fairly empty and we made our way to the rear of the café. Behind us, and behind closed glass doors, was a coffee roaster that we later discovered was part of the Old Spike roasting expansion. It’s always a nice touch to see coffee roasting happening as you drink but perhaps we needed to arrive earlier for that.

Bricks with holes Spike and Earl — Holes in bricks at Spike and Earl. Just a foot-hold or a suggestion for a great piece of engineering?

Drinks arrived together with complementary water and the soya latte was very smooth. Almost caramel like in the sweetness and very drinkable. It makes a pleasant change to have a latte once in a while. Light was playing tricks around the room as the sun was setting and the inside lights were becoming more prominent. But the striking thing about Spike and Earl was that the bricks used to support the tables and line the walls all had holes in them. On the wall running along the side of the café, (windows were on the other side), pot plants were placed in the holes giving the impression of the beginnings of a green wall. The holes in the bricks supporting the table meanwhile made an excellent footstool and were complemented by holes in the stools. A latte of course is largely made up of holes, or at least bubbles. The foam structure consisting mostly of air. How is it that some structures can be made better owing to what they don’t contain rather than what they do?

For example, if you imagine the difference between a latte and a cappuccino (but made out of metal rather than milk) that can be the difference between a successful tooth implant and a failure. We know from our coffees that bubble size can have a significant structural effect. But how about more fundamental properties, can the holes in bricks change things such as the way sound propagates?

Interior wall at Spike and Earl — More bricks with holes at Spike and Earl, this time with some plants escaping from them. The start of a green wall?

You may have heard about how different structures can be engineered to make materials “invisible” to certain frequencies of light. Imaginatively named “invisibility cloaks” are made by designing materials with patterns on them that change the path of an incident light beam. Because the effect on the light beam is due to the structure in the material rather than purely from the material itself, these materials have become known as ‘meta-materials’. When you remember that microwaves are a form of light, it is perhaps easy to see some of the applications of this research and one reason that it has attracted a lot of funding.

However there is an acoustic type of metamaterial that is far more similar to the bricks in Spike and Earl and that may find applications in medical imaging (ultrasound). Earlier in 2017, a team from the universities of Sussex and Bristol published a study about acoustic metamaterial ‘bricks’. Each brick had a differently shaped hole through the centre of it which delayed the incident sound wave by a specific phase interval (you can say it ‘slowed’ the wave). In order to work efficiently, the brick had to be of a height equal to the wavelength that the researchers were interested in and a width equal to half that wavelength. As they were investigating ultrasound, the bricks were therefore about 4.3mm square and 8.66 mm high.

By assembling the bricks together, the researchers found that they could steer a focussed beam of sound or even change the shape of the sound beam. This would have applications as diverse as targeting cancer cells with ultrasound to levitating a polystyrene bead. You can read more about their research here (or, if you have access to Nature Communications, their paper can be downloaded here).

soya latte Spike and Earl — Layering at the end of my soya latte. What would you think about?

Just for fun, assuming that the bricks supporting the table at Spike and Earl could be similarly turned into acoustic metamaterials, we could calculate the musical note that they would best work with. Estimating the brick at about 15cm square and remembering that is approximately half the wavelength (λ/2) and using the speed of sound in air to be 330 m/s, we can calculate the frequency to be:

f = c/λ

f = 330/0.3 = 1100 Hz

Which is the musical note C#6 (with an explanation of nomenclature here).

As I finished my soya latte, strata of milk lined the cup. Reminiscent of the Earth’s layers or perhaps, metaphorically, our strata of understanding, there is certainly plenty more to ponder at this interesting new(ish) addition to the London café scene. So next time you are in Spike and Earl, do let me know what you end up thinking about, you never know where these thought trains may take you.

Spike and Earl is at 31 Peckham Road, SE1 8UB