Back in black (hole) – A review of June’s SciBar


Professor Philip Moriarty becomes the first SciBar speaker to require a sound check as he brought his guitar in order to talk about what happens when physics goes up to 11. Black holes? How much more black could they be? None. None more black.

In quantum physics, we always think of atoms and molecules but we should actually be thinking about waves. How do these particles react in terms of waves spreading in space? Sound also travels in waves. Hence we can see a connection between quantum physics and the world around us since we are surrounded by waves.

This image consists of 50 iron atoms and was created with a scanning microscope. Pushing atoms around at 4 degrees above absolute zero in a vacuum, the coral was created. Down at this size, we’re talking about nanometres, which is how much your hair grows every second. However, the mathematics that describe this shape are the same as those that describe a drum being hit.


There was an article in Physical Review Letters looking at the collective motion of humans in mosh and circle pits at heavy metal concerts. It turns out that people behave just like molecules. More than that, they even obey the Maxwell-Boltzmann Distribution.

In the words of Leibniz, “Music is the pleasure the human mind experiences from counting without realising that it is counting” There is a direct link between numbers and music as musical theory is all based around the concept of intervals – thirds, fourths, fifths and octaves. Is this a way of connecting with people who don’t like maths?

Professor Moriarty then goes to talk about why an “A” on a piano sounds different to an “A” on a guitar. It’s the same note on a treble clef so why does it sound different? It’s all down to overtones and harmonics. The fundamental frequency is the same but an oscilloscope would show the difference.

And then we get a quote from Fourier that sums up the whole talk, ” Mathematics compares the most diverse phenomena and discovers the secret analogies that unite them”

With that said, it’s onto Heisenberg’s uncertainty principle and how you can describe it with a guitar. Where you have a sound that is long in terms of time, it is narrow in frequency. If you dampen the strings, you get something that is shorter in time and needs a much broader range of frequencies to describe it. So, if we can measure the time, we can’t accurately measure the frequency.

There is also a spatial frequency which is the number of waves per unit distance. Compare this to frequency which is cycles per second. We already know that every single image that we see is waves as light reflects off objects and if we filter at high frequencies then we lose definition. Either way we look at it, we can see that the uncertainty principle is inherent in waves – it’s not actually a quantum thing at all.

With Heisenberg out of the way, we get a more philosophical question – can you hear the shape of a drum? You can hear the shape of a string so why not a drum? Well, having built drums at the atomic level to solve this problem it turns out that you can’t hear the shape of a drum after all.

In the Q and A session after the talk, we learn that even people have a very small wavelength associated with them. We talk about “fuzzy balls” – the largest object that displays diffraction properties. Finally we hear about where Professor Moriarty hope that his research will take him next. No, not outwitting Sherlock Holmes but whether it’s possible to do 3D printing with atoms.

With that the guitar gets put away and we all leave knowing that the next time we see Tony Iommi or Angus Young play, they’re not just playing riffs, they’re demonstrating physics.