Tag Archives: physics

Music: An Explanation by a Guitar Hero

Better late than never? Having been on holiday I’m a little late with this short write-up of an Edinburgh International Science Festival event but, as it was so good, here goes.

Dr. Mark Lewney is a physicist and a guitarist. Last year I went to his excellent Rock Guitar in 11 Dimensions and reviewed it here. This year he presented Music: An Explanation by a Guitar Hero – a look at the physics underlying sound/music. Without wishing to spoil the show for those who may have the chance to see it later, let me say that he took us on an engaging journey from the sine wave – through the world of harmonics (overtones), the importance of the fundamental, 4th and 5th notes, the short step from there to the pentatonic scale, which is used in folk musics across the world – notably in the blues.

He finished the talk with some thoughts on music’s purpose in our evolution – the topic of much debate – such as from 2:24 – 7:03 in this video). One thing is clear, though: prosody (the music of speech) matters – it’s not just what you say it’s how you say it.

This was an excellent, funny and informative presentation. This cross-curricular take on life is, I feel, at the heart of CfE.

You can see Mark Lewney in action in YouTube videos here.

My further explorations on prosody took me here to a fascinating series of lectures by Peter Roach


I forgot to mention one of the most elucidating facts of the evening – and one of the simplest. 

When non-musicians ask musicians why orchestras need conductors, there are many common answers: 

  • apart from waving the baton, the conductor is the person who has led rehearsals and is in charge of the interpretation
  • orchestral players can end up sitting many metres away from their colleagues and it’s hard to hear – conductors can ensure the overall balance and timing of the group
  • the conductor is the fore-runner of drummer and mixing desk

 However, Mark Lewney’s audience participation illustration was much better and more direct and more memorable. He asked the audience to clap to a beat which, having started, he left in our hands – with out eyes shut. The timing soon began to drift. He asked us to open our eyes and sync with him. The timing improved. Closing our eyes again, the timing deteriorated. Opening them, and following his lead, we were back in sync. The reason? Light travels approximately 874,000 times faster than sound*. Relying on the sound, we had to wait for it to bounce off the back wall of the hall. Syncing to the beat, we were exactly in time.

 * Speed of sound

  •  343.2 metres per second
  • 1,236 kilometres per hour
  • 768 miles per hour

 Speed of light 

  • 299,792,458 metres per second
  • 1,079,000,000 kilometres per hour
  • 671,000,000 miles per hour


 Why is it sometimes so difficult for musicians to keep in time* when effortless synchrony pervades the natural and mineral world?

Steven Strogatz describes some examples in nature and the rules – including an explanation of the ill-fated Millenium Bridge and some fantastic footage of starlings swarming.

One of the most interesting things in this talk was his request that the audience try to clap in sync. I would have struggled to decide quickly whether or not this was likely to succeed. I was surprised to hear that, rather than grow into synchrony, the audience seemed to begin in sync – undirected! Moreover, had I been asked to predict the speed at which unplanned, instant synchrony was likely to be achievable, I’d have guessed 120 beats per minute (bpm) the tempo at which the world’s armies tend to march and also of much dance music. However, this TED audience began at 132 bpm – surely a curious phenomenon from a group of seated academics.

* the most common cause of ensembles slipping out of sync is losing the battle against the tendency to accelerate – a kind of negative entropy. This contrasts with the more entropic tendency of a capella singers to lose pitch. I’ve always been surprised at this dissonance in the physics and biology of our subject.


School Development Plan

The differences between Physics and the world as actually experienced, and between wisdom and usefulness could surely be brought to light no more abruptly than by submitting this single Einsteinian sentence as the sole content of your school development plan. Then it would be time to turn your attention to measuring the mass, velocity and momentum of matter hitting the fan.