Enlightenment at Timberyard, Seven Dials

coffee, Timberyard, wooden tray

Great coffee at Timberyard

It is not often that you come across an independent café in central London that has great coffee, a good deal of space and seats available and so I found myself very happy to have come across Timberyard near Seven Dials. As I ordered my long black, I was presented with a choice of bean for the espresso base. Should I have the “fruity and acidic” Jabberwocky, or the “chocolate” Climpsons? I was trying Timberyard for the first time and so the choice was easy. For me ‘chocolate’ will win over ‘fruity’ every time. However having the choice was a nice touch. Being in central London, it was of course crowded when I tried it, but there were still seats around, including some stools outside. I took a seat outside, ready to watch the people and the cars going by. After a short while, the coffee was brought over, served on a wooden tray together with a complementary bottle of water.

crema on coffee, Timberyard

The patterns as the crema breaks up are reminiscent of the coastlines of Norway and of fractal mathematics.

It was a very pleasant location to sit and enjoy my coffee while I watched people rushing by on their way to various meetings and tourists milling around, taking their time to soak in the city. As I waited for the coffee to cool, the crema on the surface started to break up and I was reminded of the coastline of Norway. It struck me that the same mathematics of fractals describes the coastlines as would describe the patterns in the crema. It was then that I noticed the street lighting. A light converted from an old style gas lamp was attached to the wall of a shop just across from where I was having my coffee. In the other direction, there was a modern lamp-post of one particular design and then, just slightly further down the road, a lamp-post of a different design. This prompted me to think about the history of street lighting and also the problems with it.

One of the first roads in England to be lit at night was the Route du Roi (nowadays known as Rotten Row) that ran from Kensington Palace to St James Park. Three hundred lamps were hung from trees along the route. These first street lights produced light by burning fuel, a method of street lighting which existed in one form or another until fairly recent times (as evidenced by the oldest street lamp visible from Timberyard). They were installed, as now, to try to reduce crime; it seems that the park used to be frequented by highwaymen. One of these had been hanged for the killing of a woman in the park in 1687. Though it wasn’t quite murder: Rather than be robbed of her wedding ring, the unfortunate lady had attempted to swallow it and so choked to death.

gas lamp, Monmouth St

An old style street lamp on Monmouth St. visible from Timberyard

A more recent type of street light was based on sodium. Applying an electric voltage across a gas of sodium caused the sodium to emit light in the yellow region of the visible spectrum. If rather than sodium, the lights had been based on neon gas, the colour of the light emitted would have been different as the colour corresponds to the different energy levels in the atoms, (for more info click here). In an effort to find increasingly efficient light sources, there is now a move into street lighting based on LEDs (Light emitting diodes). Rather like the sodium lamps, such devices work by applying a voltage over a material but in the case of the LEDs, the material is a semiconductor junction (where the energy gap can be manipulated to have the same size as the energy of visible light). LEDs have the significant advantage that the voltage supplied to produce sufficient lighting can be much less than is the case for sodium lights. This increase in efficiency is a small but effective way to limit our carbon dioxide emissions, especially when used together with sensors on the lamp post to detect when it is dark enough to actually necessitate the light being turned on.

Such a combination of energy saving measures benefits not just the planet but the public wallet. Perhaps in a few years time we’ll see such a set of eco-friendly lamp-posts spring up near Timberyard to add to the collection of street lights there.

In the meanwhile, if you visit Timberyard and notice some interesting physics or history, or if you just slow down and see something interesting, please let me know using the comments box below.

Timberyard is at 7 Upper St Martin’s Lane, Seven Dials, WC2H 9DL (and Old St, EC1V 9HW.)

London info taken from The London Encyclopaedia (3rd Ed), Hibbert et al.

Perpetual motion in a coffee cup

V60 from Leyas

Could your coffee be used to power a perpetual motion machine?

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

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

Sphinx, Brownian motion

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

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

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

Nasa, Norway, coastline, fratal

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

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

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