Coffee in St Pauls

Waiting for a green light at Alchemy, St Pauls

8 Ludgate Broadway, St Pauls

Alchemy Coffee

Alchemy, “a seemingly magical process of transformation, creation or combination”, is certainly a cafe that lives up to the dictionary definition of its name. The branch, on Ludgate Broadway near St Pauls, is the outlet that ‘showcases’ the coffee of Alchemy Roasters. On walking into this cafe, I was presented with a menu of two types of beans for espresso based drinks or two different beans for filter/aeropress. Both sets of coffees came with tasting notes. After a brief chat with the friendly barista I went for the San Sebastian with aeropress. Notes about the origins of the coffee are dotted around this superbly sited cafe (its location is ideal for people watching). The coffee is directly traded (where possible) and, if lattes or cappuccinos are your thing, there are also details about the farm that produces the milk.

Although there were cakes on the counter, I had just had lunch and so had to pass on what looked to be a good selection of edibles. The coffee though was certainly very good and definitely an experience to be savoured. As, perhaps I should have expected, when the coffee arrived it came in a beaker reminiscent of chemistry laboratories. From my chair in the corner, I could watch the preparation of the coffee behind the counter, the people coming into the shop to order their coffee and the crowds passing by outside.

E=mc2 Einstein relativity in a cafe

Scales at Alchemy. Weights on one side, chocolate on the other, it can only mean one thing: energy-mass equivalence

Close to where I was sitting was an old style set of measuring scales. This see-saw balance had weights on one side and chocolate on the other. Perhaps this connection seems tenuous, but for me weights on one side of the scales and an energy bar (chocolate) on the other side could only mean one thing:


The equation relating energy and mass for a particle at rest derived, and made famous by Einstein. The equation comes from Einstein’s theory of special relativity which states that nothing can be accelerated to faster than the speed of light (in a vacuum). First set down in 1905, the theory has some very odd predictions, among which the best known is probably the twin paradox (details here). The idea is that a moving clock will be observed to run slowly by a stationary observer, a prediction that has been confirmed several times by experiments using atomic clocks (here).

San Sebastian via Aeropress

Coffee is served at Alchemy

Moreover, the equation states that mass and energy are equivalent and that a small amount of mass can produce an awful lot of energy, (details here). A detail which will bring this story of a cafe-physics review nicely back to the Alchemy cafe, to London and to the importance of slowing down. The connection is through a set of traffic lights in Bloomsbury. Back in 1933, Leo Szilard was waiting to cross the road at the traffic lights at the intersection of Russell Square with Southampton Row. Szilard had recently escaped from Nazi Germany and was spending his time as a refugee in London pondering different aspects of physics†. That September day, Szilard was thinking about a newspaper article featuring Ernest Rutherford that he had read earlier. In 1901  Ernest Rutherford, together with Frederick Soddy, had discovered that radioactive thorium decayed into radium. The changing of one element into another could be considered a type of modern day alchemy. However Rutherford did not believe that there could ever be a way of harnessing this nuclear energy. In the article read by Szilard in The Times, Rutherford had dismissed any such ideas as “moonshine”. Szilard was forced to pause his walk as he waited for the traffic lights to change. Those few moments of pause must have helped clear Szilard’s mind because as the light went green and Szilard was able to cross the road, a thought hit him: If every neutron hitting an element released two neutrons (as one element was transmuted into another), a chain reaction could be started. As part of the mass of the decaying atom was released as energy, it would mean that, feasibly, we could harness vast amounts of energy; E=mc².

This idea, a consequence of spending five minutes waiting for a traffic light rather than checking Twitter (not yet invented in 1933), proved to underpin both the nuclear fission which we use in electricity generation and the nuclear fission that we’ve used to develop weaponry. It makes me wonder what alchemy we could conjure in our minds if we stopped to enjoy the transformations of the coffee beans at Alchemy.


Alchemy (cafe) is at 8 Ludgate Broadway, EC4V 6DU

† A book that some may find entertaining is:

“Hitler’s Scientists”, John Cornwell, Penguin Group publishers, 2003. The book contains this anecdote about Szilard: As Szilard was of Hungarian-Jewish descent, he fled Germany to Britain via Austria on a train a few days after the Reichstag fire of 1933. On the day he left, the train was empty. One day later, the same train was overcrowded and the people leaving Germany were stopped at the border and interrogated.  An event that prompted him, a few years later, to reflect “This just goes to show that if you want to succeed in this world you don’t have to be much cleverer than other people, you just have to be one day earlier than most people.” Something to reflect on in today’s refugee crisis perhaps.

Gravity and Grace at the Wren cafe

Wren cafe, St Nicholas Cole Abbey

Inside the Wren cafe

There is a lot to like about the Wren cafe. Firstly, there is the space that it occupies (inside St Nicholas Cole Abbey). I went at lunchtime when the way that the light came through the stained glass windows made the cafe a very relaxing and open space. The coffee is from Workshop, complementary water came in 3 flavours (mint, cucumber or lemon) while the food is cooked on site. This is important because it means that they have a great nut policy and could tell me which dishes were likely to contain nuts etc. A further nice feature of the lunch menu at the Wren was that you could select your portion size. Food waste is a major issue for our society and is not helped by the ‘one size’ portions served at many food outlets and cafes. Lunch was offered in two sizes (technically as a side or a main) but the ‘side’ was more than adequate for a mid-week lunch. Sofas in the corner of the room meant that you could relax and take in your surroundings in a comfy environment or, if you were just there for lunch, ordinary chairs and tables were dotted around the room.

Of course, a place such as this will have plenty of things to notice about it. Whether your interest is in architecture or science, there is plenty to observe around you. What I would like to focus on though is a bit of science history that connects the name of this cafe with Isaac Newton, John Theophilus Desaguliers and the dome of St Paul’s Cathedral (which you can see from the front of St. Nicholas Cole Abbey).

View of the Dome from the cafe

The Dome of St Paul’s, visible from the side of the Wren cafe.

Perhaps we all remember the story told to us at school about how Galileo dropped two balls of different mass from the top of the leaning tower of Pisa. According to the story, the balls fell to the earth at the same time, thereby showing that the acceleration due to gravity was independent of the mass of the object and paving the way for Newton’s theory of gravity. Sadly, it seems that Galileo may never have actually performed the experiment (even if it was “re-created” in 2009). However there is evidence that Isaac Newton did perform exactly this experiment in 1710 from the dome of the soon-to-be-completed St Paul’s Cathedral.

“From the top of St Paul’s church in London in June 1710 there were let fall together two glass globes, one full of quick silver [mercury], the other of air”¹. The globes fell 67m before shattering onto the cathedral floor (I’d hate to have written the risk assessment for that experiment). To avoid the possibility of human error, a trap-door mechanism had been designed to ensure that both globes dropped simultaneously. According to the story of Galileo told to us at school, we can calculate how long it would have taken those globes to drop to the floor: 3.7 seconds, independent of mass. So is this what Newton observed? No! The heavy glass globes took 4 seconds to fall, but lighter ones took 8-8.5 seconds! A few years later and Desaguliers repeated the experiment from slightly higher in the dome (but this time with hog’s bladders rather than glass) and obtained the same result.

View of St Paul's Cathedral London

Another view of St Paul’s. Hard to believe that Newton actually dropped liquid mercury from the dome.

This surprising result can be explained when we realise that Newton was investigating not gravity, but air resistance. While the gravitational acceleration is independent of mass, the upwards force due to the air resistance depends primarily on the object’s size (and velocity). This means that the deceleration caused by the air resistance will be different for two globes of the same size but different mass (Force = mass x acceleration). Heavy objects will fall faster in air (until the objects reach their terminal velocity).

There is a certain irony in the fact that this result is opposite to what we feel should happen based on what we learned at school of Galileo’s experiments challenging the scientific orthodoxy of the time. However the result of Newton and Desaguliers’ experiments do not contradict the theory of Newton or Galileo, they just add an extra layer to the problem. We do not exist in a vacuum, we need to think about the air around us too.

Both Newton and Desaguliers were regular coffee drinkers albeit at different coffee houses. Desaguliers frequented the Bedford Coffee House in the north east corner of Covent Garden while Newton regularly retired to the Grecian in Devereux Court (just off Fleet Street). Coffee houses were places that the latest science, politics or philosophy were discussed and debated. The Wren describes itself on its website as existing to “serve the ministry of St Nick’s talks“. Sadly I experienced no discussion or debate on my visit (just a very nice, but solitary, lunch and good coffee) but it is interesting to see the tradition of the 17-18th century coffee houses continued in this Wren designed church and cafe.

The Wren cafe can be found inside St Nicholas Cole Abbey, 114 Queen Victoria St. EC4V 7BJ

[1] The Dawn of Fluid Dynamics, Michael Eckert, Wiley-VCH (2006)

Coffee house info: London Coffee Houses by Bryant Lillywhite (pub. 1963)