Quintessence: echoes across science

I’ve been reading up on the story about cometary material found in Libya (odd pebble is cometary material fallen to earth). My plan to write about it myself has run into the desert sands – I have nothing new to add. However reading the source paper has taken me off on a tangent, inspired by the word quintessence. It is a word that rolls off tongue rather nicely. It also has so many interesting meanings that I want to talk about them a little.

Non-scientific

Quintessence has been defined1 as:

1. A thing that is the most perfect example of its type; the most perfect embodiment of something.
2. A pure substance.

For these everyday meanings you might use it like you do the more common word quintessential, for example to make a science fiction film seem profound: “Hope, it is the quintessential human delusion, simultaneously the source of your greatest strength, and your greatest weakness”

Proto-scientific

The word comes from Medieval french, meaning ‘fifth essence’.  At this time, attempts to understand the natural world were often framed in terms of Ancient Greek concepts, based on the works of authors such as Aristotle. The world was seen as being made up of 5 elements, or essences. Fire, earth, air and water covered the everyday. The fifth, ‘highest’, essence, also known as aether was contained within everything and was also the material that made the heavenly bodies.

Hindsight is a wonderful thing. Having the benefit of hundreds of years of scientific progress, grounded in experimental observation, it is tempting for us to be dismissive of our ancestors ‘mistaken’ opinions. Take alchemy for example. Isaac Newton, has (largely since his death) been seen as the quintessence of a rational scientific genius. However in reality he was a keen student of alchemy (and of other occult studies).

Alchemy (like astrology) came from genuine efforts by intelligent people seeking to understand the world. There is an interesting thread in contemporary studies of the history of science tracing the connections between the concepts of modern science and these older beliefs.

The aether

One example of this is the scientific concept of aether. To the Ancients, it was linked to the heavens and the quintessence underlying everything. In alchemy the name became mixed up with the idea of elixirs or medicines. In 1730 German scientist W.G. Frobenius changed the name of chemical compound ‘sweet vitriol’ to ether, a name now attached to a whole related group of organic compounds.  Having found a good way to manufacture ‘sweet vitriol’ he was keen  to sell it – perhaps naming it ether (thereby invoking a heavenly universal medicine) was simply marketing. Ether has since been uses as a solvent, an anaesthetic and a narcotic to use while driving from LA to Las Vegas to find the American Dream.

The name aether also resonates strongly in the world of physics. Seventeenth Century studies of optics, notably by Christiaan Huygens led to theories explaining light in terms of waves. If light involved waves, then some substance must be present for the waves to act on. This was known as the aether. Only with the Twentieth Century understanding of the weirdness of wave-particle duality (light is caused by little particles (photons) that behave in wave-like ways) was the concept of aether no longer required.

Modern physicists attempt to reconcile observations of the incredibly large (cosmology) and unimaginably small (particle physics). Gaps between theory and observation lead them to infer the existence of dark energy, one proposed form of which is given the name of quintessence. Whether this a purely hypothetical concept that will go the way of aether is not something a mere ex-geologist can speculate on.

And finally

What about the Libyan cometary material, this interesting pebble found in the Sahara?

The scientists involved were only given a gram of material which they then subjected to a whole battery of analytical procedures2. One of these involved heating it and analysing the gases that come off. Typically chondritic meteorites – chunks of the primordial solar system – contain a component known as Q, short for quintessence. This is thought to represent the ‘ambient gas of the early solar nebular’. The solar nebular is the cloud of dust, gas and ice from which the everything in the solar system (including you and everything you’ve ever seen) was born. There is no quintessence in the Libyan fragment, suggesting it did not form in the inner Solar System, but can only have formed far out where there is little gas at all. Out there, between 30 and 50 times further from the sun than we are, is comet country.

Another name for the gas know as quintessence is ‘planetary 1’, which is as dull a name as you could imagine. I salute the person who named it quintessence. Science rests on the precise use of technical terms, all of which have names. Giving them beautiful names with resonance and historic significance keeps us in touch with the poetic. The Ancient Greeks yearned to understand the mysteries of the world around us. Using words like quintessence reminds us that we are driven by exactly the same quintessentially human urge.