Back when I was a kid, I had two interests in life, physics and playing music. In music my favourite instrument was the church organ. Over the following years those two interests merged into one as I got interested in how soundwaves form, and onwards into what I usually call waveform theory. Waveform theory is applicable to many things from large scale physics all the way down to quantum electro-dynamic interactions, and volcanoes.
I also have a deep-rooted love of deducing on my own complex things from basic principles instead of root learning mathematical formulations. The reason for this is that I can’t memorize things if I do not understand them fully, and the only way of doing that for me is to walk my way from basic fundamental principles to the end result.
Combine that with a brain that refuses to see any problem from a single point of view and that rapidly tries to deduce five different solutions to a single problem from fundamental principles and you get someone with a propensity for over-heating the piece of lard that is the human brain.
Music and physics have always been integrated as a whole for me. In a sense of it I learned more about mathematics from the grand fugues by Bach, then I ever did by studying mathematics.
As things went on my love of Fugues, Riemann, inventing ways to cheat the lightspeed limitation and playing music was in the end slightly interrupted as I discovered that kissing girls was also quite nice.
I thought I should give a short personal backdrop for the third part of this article. But before returning to huge organs we need to contemplate Gandalf’s Pipe.
Gandalf’s Pipe and the Art of Smokerings
I must thank Janine Krippner for the idea of the first part. She trumped out a question to the Twitterverse about the physics of volcanic smokerings instead of using google.
So, for the edification of Janine Krippner I will explain Gandalf in a physics 101. This explanation will work for anything that has a somewhat round opening of the barrel and has a temperature and pressure differential happening.
I will first explain it from the point of a gun and then go for pipesmoking before ending up at a volcano.
Smokerings are governed by 3 effects, and Wikipedia gives a good explanation for one of them. The 3 effects are central piston driving force, friction of the colder outer air, and the Coanda effect.
The central piston driving force comes into play since the air in the center of the smokering vortex is travelling fast than the air on the outside of the smokering. This gives the inner side a positive energy surplus. Also, the same effect applies to warm central core air rising.
The outer air is colder than the air in the centre and colder air causes more friction than warmer air. This functions as an air brake.
These two effects will cause a vortex to form with the inner side spinning upwards and out (from heat and piston force) and a slower outside (from air breaking due to friction). The beauty of this is that the ring will be self-centring and will not disperse rapidly. As long as the principles are acting the vortex will happily spin about.
This pretty much explains what is happening if the heat differential is large, or the piston force is great, like from a gun barrel or a volcano. The problem with this is related to Gandalf and his poor mouth.
As any pipesmoker trying to blow a smokering can attest to is that it is harder to produce a smokering than you would assume. You have to blow out the smoke slowly (low piston force), and the smoke will come out at body temperature in a room that is normally room temperature.
Gandalf could probably conjure up dragon fire temperatures as he blows smoke, but for the rest of us we find that there is a decided lack in both piston driving force and temperature differential.
And this problem affects poor Etna as she blows her smokerings out of volcanic gasses. Problem here is that these circular vortexes of gasses does not emanate with great force, nor at a great temperature differential (for coming out of a volcano).
To explain this, we have to go back to early aeronautics and one of our most forgotten geniuses, Henri Coanda. As he designed an aircraft in 1910, he discovered that the exhaust gasses tended to stick to the surface of the fuselage.
In the aircraft example it was the tiny force of the ambient air pressure the forced the gasses towards the fuselage and there the friction takes hold of it and drags it across the skin of the fuselage. In a barrel, volcanic vent, or indeed a mouth, it is the pressure differential of the exhalation that pushes the gasses/smoke against the sides of the “barrel”, there the friction takes over and creates a vortex embyo even before the smoke has left the mouth.
Obviously, I have simplified things a lot here, but the basic parts are accurate. And since a barrel is a pipe of sorts, we are now ready to discover why Mayotte is a church organ.
Notre-Dame de Mayotte
On the 11th of November this year an earthquake occurred near the Island of Mayotte. The combined seismic energy release was equivalent to an M6.1 earthquake. The duration of the seismic signal was longer than 20 minutes and it had an unusual monochromatic waveform.
What surprised me was that even trained geophysicists stated that this was a mystery. The surprise on my part comes from having seen this type of signal from volcanoes prior and during eruptions. Both the eruption of Tanganasoga in El Hierro and the 2014 eruption of Bardarbunga produced the same seismic signals at far lower signal strength.
With a 7-year head start on things I could smugly point out that I knew exactly what it was with a certain degree of certainty.
The easiest way to explain it, is to start with the humble organ pipe. So, please watch this video for the basic physics of how an organ pipe works.
Now, let me recapitulate that video to give some fundamental principles.
- The longer the pipe, the lower the note will be.
- The higher the air pressure is, the louder the note will be.
- The higher the air pressure is, the wider the pipe must be. Otherwise the note will start to transpond into higher frequencies.
- Fluid will also create a sound when going through an organ pipe.
- A volcanic conduit is to all points and purposes an organ pipe.
Geophysicists are very good at finding and explaining different types of earthquakes. But when an earthquake sized signal occur it is easy to get lost, especially when it is not even remotely caused by an earthquake.
We know from the prolonged and very energetic swarm of regular earthquakes that something is happening there. And from the trajectory changes at remote GPS-stations we know that it is something sizeable that is intruding in the waters outside of Mayotte.
Even before this large seismic organ note we knew that there was a volcanic embryo forming in the waters outside of Mayotte. It is believed that the volcanic region is driven both by the cracking of the African continent and the African super-plume.
Not an unreasonable assumption since it would take something fairly momentous to produce a volcanic organ note of such prodigious sound force. As such it is the loudest single frequency sound ever recorded.
Since we know the frequency and the volume, we could even in the end be able to get a fair assumption of the length and width of the volcanic conduit (organ pipe). Even though we will never be exactly sure of the result, we could at least remove the more outlandish candidates of length versus width.
We could then in turn make assumptions about the volume of magma that moved during the event.
All of the large organ pieces by Bach work like immense mathematical formulations based on rules. They are the grandest example of the musical expression of mathematics and physical foundations of our Universe.
And as a coda to this article I would like to present to you my favourite organ piece, The Toccata, Adagio and Fugue in c-minor.
If you listen carefully at the beginning you will hear a question being asked, it is then explained in the next two bars through what is in essence a mathematical formulation. And as you keep on listening you will realise that the question is in effect the same as the answer and is super-symmetrical.
As the piece evolves the same question will come back and be proven through the variations of the theme. And in the grand finale you have five simultaneous lines of questions and answers solving the problem from five different points of view.
This is exactly how I see our glorious Universe, and it is hauntingly beautiful.