Coffee review Observations Science history slow Tea

Pushing it at Lever and Bloom, Bloomsbury

Lever Bloom coffee
Lever and Bloom under a blue sky.

Does a take-away need to be rushed? A coffee so quick that there is ‘not enough time to prepare a flat white’? Are we always so preoccupied with the distractions of our day that we consume our coffee merely for the pleasant caffeine kick that it provides?

Lever and Bloom in Bloomsbury is a great example of why this does not have to be, indeed should not be the case. Since 2015, Lever and Bloom have been operating out of a cart on Byng Place close to UCL and a number of other research institutes. The character of the surroundings really does affect the space and both times I have been to Lever and Bloom I have either met interesting people in the queue or overheard snippets of intriguing conversation about history I know nothing about.

Coffee Bloomsbury reusable coffee cup
Long black in a keep-cup and telephone box in Byng Place.

It is easy to spot the coffee cart in the corner. Firstly, it is bright red and quite eye catching but secondly because of the queue forming in front of it. Don’t be put off though, the queue moves very quickly so you won’t wait long even if you are in a rush. Queueing however does give you an opportunity to peer into the cart. Space is used extremely efficiently. with each piece of equipment  apparently having its own perfect home. It reminded me of a childhood game of trying to fit in as many objects as possible into a matchbox. A cabinet on the table in front of the cart displays cakes including cinnamon rolls (sadly sold out by the time I arrived in the afternoon). It was also nice to see the number of people ahead of me in the queue who were using re-usable cups.

The lever of the name refers to the (Izzo Pompei) lever espresso machine that is used on the cart. It was fascinating to watch the ground beans being carefully tamped and the lever being pulled to prepare the espresso. Although there is some debate as to the optimum water pressure needed for preparing an espresso, the standard pressure is 9 Bar; water is pushed through the tamped grinds at nine times the atmospheric pressure at sea level. Watching these espressos being prepared reminded me of preparing ceramic samples of an interesting magnetic material a few years ago. We were interested in the electrical properties of a class of materials called manganites. To prepare the materials for measurement we first had to grind the pre-cursor powders (but with a pestle and mortar, no burr grinders) and then, after a couple of further preparatory steps, press them into a pellet ready for firing in the oven. The machine used for pressing the pellets had a lever, not dissimilar to that on the espresso machines and yet, the pressure that we used for the pellets was roughly 1000 Bar. This high pressure was needed so that dense pellets of manganite material would be formed when we heated it in the oven (typically at 1200 ºC). Just as a good espresso depends on the pressure and then the temperature and time of extraction, so the properties of the pellet would be affected by the pressure and then temperature and time of firing in the oven.

Portland Stone fossils
Fossils in Portland Stone. It is astonishing what is revealed when you slow down and notice the buildings around you.

Similar effects affect the rocks of the earth, something that is particularly visible in the area around Lever and Bloom. A geological walking tour around Byng Place, Tottenham Court Road and towards the British Museum illustrates this particularly well. Behind Lever and Bloom, the church of Christ the King is built from Bath Stone. An oolitic limestone, this type of rock is formed of compressed sand and bits of shell. Much as the manganite samples of my study before they were fired in the oven but of a more interesting colour. Heading towards Gower St and the impressive UCL building is made of Portland Stone. Another limestone, this building material is a goldmine for urban fossil explorers. Continuing the walk, on Tottenham Court Road, the Mortimer Arms pub is fronted by quartzite while Swedish Green Marble adorns 90 Tottenham Court Road. Quartzite and Marble are both types of metamorphic rock, formed by pressing together different precursor materials at high pressure and temperature. Other types of marble can be seen on the tour, suggesting the influence of pressure and temperature of formation on the rock structure as well as the type of precursor rock.

It would seem that such a walking tour is perfectly timed for a longer style of coffee, perhaps a latte (in a re-usable cup of course) from such a centrally located place as Lever and Bloom. And of course, assuming you are using a re-usable, there is even more to ponder. The pressure and temperature during the manufacture of the re-usable cup would have affected the properties of the cup (or in my case, glass).

Let me know if you spot any interesting rocks or fossils during your time at Lever and Bloom but whatever you do, I hope that you can enjoy your coffee and then slow down to enjoy it a bit more.

Lever and Bloom is at Byng Place, WC1E 7JJ

Coffee review Observations Science history

Quantum physics from your (re-usable) cup at Lost Sheep, Canterbury

Coffee in Canterbury, keep cup
Finding the sheep. Lost Sheep coffee in Canterbury. Note the lighting.

I have long been looking forward to trying the Lost Sheep coffee pod in Canterbury. How would the reality compare to the friendly and knowledgable impression they give on social media? Being mostly a take-away outlet, what was their attitude to the disposable coffee cup problem? We had ensured that we had packed our keep-cups when we left London so that we could enjoy a coffee without having to use a disposable cup. Little did we know.

The sheep was visible as we approached the Lost Sheep coffee pod from the direction of the High Street. Adjacent to the pod, people were drinking their coffee while standing at the chip-board standing-bar nearby. In front of us in the queue, another customer was buying what appeared to be his usual coffee in his re-usable cup. The conversation between the customer and barista showing that cafés that help build communities do not have to come in standard formats. ‘Pods’ can work as well as cafés inside buildings (though the Lost Sheep has one of those too over in Ashford). The queue ahead of us enabled us to take more time to study the environment of the Lost Sheep.

Interestingly, a set of ceramic cups were placed above the espresso machine. Although we saw none in use, presumably this means that should you wish to enjoy your coffee at the bars, you can do so, even if you have forgotten your reusable. What a great feature for a take-away coffee place. The friendliness of this café was apparent as I presented my keep-cup for my long black. Commenting on the design of the cup (glass with a cork handling ring, perfect in size for the coffees I mostly drink), we continued to enjoy a short conversation about keep-cups and how nice the size was for the coffee. The coffee was amazingly fruity, a sweet, full bodied brew roasted locally in Whitstable. It was great to be able to enjoy this interesting coffee while wandering as a tourist in my old home-town.

Coffee Canterbury Sheep
Behind the sheep. At least it is easy to spot from all angles.

Before leaving the Sheep though, we did notice the lighting. A yellow hue from the lights immediately above the espresso machine with a whiter, harsher light from the luminescent strip light at the edge of the pod (a dull sunlight surrounding the rest of the outdoor space on this cloudy day). Coals are red hot, the Sun appears more yellow, how does colour vary with temperature? And how does this link to an old story that links quantum physics (very quickly) to your coffee cup.

How things absorb and emit light and electromagnetic radiation has been a subject of study really since white light was split into its different colours and then it was found that there was ‘invisible’ light beyond the blue and far from the red. It was known in the nineteenth century that things (which physicists tend to like to call ‘bodies’ for reasons that become clearer later) that absorbed all the light incident on them re-emitted the light unequally. As they absorbed all the incident light, they could be called a ‘black bodies’. People knew that the radiated light from a black body formed a spectrum that depended upon the temperature of the body. For most things that we encounter on earth, such as the coffee cup, their temperature means that they will emit more strongly in the infra-red, we can feel the heat coming off of them but we can’t see it. But as things get hotter they start to glow ‘red-hot’ and then if we heated them still further, they would glow with different colours.

The stars show this with the colour of the star being an indicator of the temperature of the star. Stars that are very hot shine blue, those that are cooler (but still thousands of degrees Celsius) appear to us as more white. Although these stars are emitting light at all frequencies, they show a characteristic peak in emissions for one frequency. The corresponding “black body spectrum” was very well known in the nineteenth century but the problem was that classical physics just could not explain it. Attempts were made to describe the curve but when it came down to it, if the energy (ie radiation) was described using classical physics, the shape of the curve could not be explained. While classical physics predicted the shape of the curve very well at long wavelengths (reds, infra-reds), there was a failure at shorter wavelengths. And not just a failure, it was a catastrophe: the theory predicted that an infinite amount of energy would be emitted at the low wavelengths. Clearly this is wrong, nothing can emit an infinite amount of energy and so for this reason, the problem was described as the “ultra-violet catastrophe“.

Sun, heat, nuclear fusion
The Sun is our nearest star and source of heat. But what links coffee to the Sun? It turns out a great many things of which this is just one. Image © NSO/AURA/NSF

A solution came when Max Planck changed the assumptions about how energy was emitted or absorbed. Rather than the continuous emission that was expected in classical physics, Planck reasoned that energy was emitted in discrete packets and that, crucially, these “quanta” were dependent on the frequency of the light being emitted. Planck’s formulation allowed for a mathematical description of the curve. Finally the shape of the black body spectrum could be explained, but it came at quite a cost; it came at the expense of classical physics. To use Planck’s formula meant abandoning some aspects of classical physics in favour of a new quantum model and it meant leaving the absolutes of classical mechanics and entering into a new statistical world. This change didn’t come easily even to Planck who had been motivated to study physics by the absolute answers that the theory of thermodynamics seemed to provide. He wrote, regarding his own black body theory:

“… the whole procedure was an act of despair because a theoretical interpretation had to be found at any price, no matter how high that might be”

In some ways, that feeling that you experience while warming your hands on a cup of steaming coffee while basking in the late afternoon sunshine is an intrinsically quantum experience. Neither the infra-red heat of your cup nor the colour spectrum of the sun could be explained using purely classical physics. So while taking time to appreciate the heat of your coffee, perhaps it’s worth remembering that this feeling that you are experiencing comes as a result of the same physics as determines the hot glow of stars and the cold microwave glow of the universe. The coffee heating your hands is indicating that the world is stranger than you may think, a quantum world being revealed to you all the while you sip your coffee.

Lost Sheep coffee is in St George’s Lane, CT1 2SY