Author Archives: Niko Yiannakoulias

On rhubarb clusters


Many, many years ago I had a friend who was very smart, and had a predilection for saying all sorts of stuff that seemed both facilitating and ridiculous.  One thing I remember him saying is that any time there is a crowd of extras in a movie that have to make background conversation, they were instructed to say the phrase ‘rhubarb cluster’.  He said that when everyone in a crowd says the phrase ‘rhubarb cluster’, it simulates a conversation, and keeps their lips moving in a way that looks realistic on film.  There are other advantages too.  He said it keeps the extras focused on doing something other than staring off into the distance in a way that could distract from the main movie scene, and it ensures that no actual words are heard or understood by the movie watcher (imagine the grief of two extras in a scene overheard saying “dude! I got so STONED this past weekend” on the audio track of a blockbuster).  In short, by instructing the extras to say a specific phrase, a director keeps control of the soundscape.

I have wondered for years if this would work in the real world, or if my friend was making it all up, but I never really followed up any further.  A few weeks ago I told my 6 year old daughter about this (almost certainly apocryphal) use of ‘rhubarb cluster’ in film, and she suggested I run an experiment using students in one of my classes to determine if it is at all plausible.  So I did.  Below, I present the methods and results.


I stood at the front of a class of about 70 students, turned on the voice recorder on my cell phone, and had them say three things.  First, I had them say the phrase ‘rhubarb cluster’ repeatedly for about 10 seconds.  Second, I had them say the alphabet repeatedly for about 10 seconds.  Finally, I had them carry on a conversation with their neighbour for about 10 seconds.

Then I cleaned up each sound sequence.  I cleaned them in two steps.  Step one was to trim out the audio after a short ‘burn in’ period.  I had to do this because for the first few seconds, the phrase  ‘rhubarb cluster’ is quite audible:

I did this for all three audio clips.  Then I normalised the volume levels for each clip to the same level.

I then combined the audio clips into a YouTube video:


Finally, I set up a short online survey for my students, asking them to watch the video, and then identify which of the clips was ‘rhubarb cluster’, and which was real conversation.  Based on the method of administering the survey, I could not set up a proper choice set experiment (with random order of audio clips, for example), but I am not sure that would have affected the results much.  Speaking of which…


Of the 80 students that answered the survey, around 63% could correctly identify the real conversation.  By itself, that could suggest that ‘rhubarb cluster’ does not perfectly simulate audible conversation, and probably could not be used as background conversation in a film.

However, in processing the audio, I did notice something interesting about the sound levels of the three clips:

The first third of the clip is ‘rhubarb cluster’, the second is the alphabet, and the third is natural conversation.  The first section has a much more stable noise level over time than the natural conversation (the third clip), even after adjusting for different average noise level.  In other words, ‘rhubarb cluster’ yields a more predictable sound profile than natural conversation, especially after the burn in period.  For audio engineers this could be an advantage, since it would allow them to record audio at a high volume without worrying about ‘peaking’ sound levels.  Peaking sound levels results in unwanted noise and distortion on recordings, and is generally avoided in audio recording.


The experiment here was not perfect, but I think it’s fair to say that the results do suggest that when spoken by a small crowd (in a university lecture room) ‘rhubarb cluster’ is detectable on a digital audio recording, perhaps even to the majority of people hearing it.

Having written that, the idea of having a crowd of extras in a scene on a movie set saying some predefined phrase doesn’t seem totally ridiculous.  It would give the crowd some predictable behaviour to simulate and it could make sound recording easier.  In the experiment I conducted students could tell the difference, but perhaps a longer phrase or a longer burn in period would have made the phrase less detectable, and make the sound more natural.  Perhaps I’ll try that in next year’s class!

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Neo-Marxism and the Fermi paradox

Enrico Fermi, a Nobel prize winning physicist, probably said and did many interesting things over the course of his life, but the only thing I know about him is that he is responsible for what people now refer to as the Fermi paradox.

By Department of Energy. Office of Public Affairs [Public domain], via Wikimedia Commons

In short, the Fermi paradox says that given the vast quantity of stars in our galaxy, and the virtual certainty that many of these stars are encircled by Earth-like planets, why hasn’t earth been visited by aliens from these planets?

There are many possible answers to this paradox, all of which are pretty speculative.  A few examples:

  1. Supernaturalism (god(s), magic, etc.)
  2. We are regularly visited by aliens and don’t know it yet
  3. Alien civilizations are waiting until the universe is a bit cooler, and it is more efficient to travel great distances (the Aestivation hypothesis)
  4. Intelligent life is really, really rare

Well, I have a favourite answer to this paradox, and it’s kind of Marxist.

Before I proceed, I should say a couple of things.  First, I am not a Marxist, I don’t practice or even like Marxist scholarship, and I am not making any claims about the way the world ought to be.  This is more of a thought experiment than anything.  Finally,  I seriously doubt that I am the first to discuss this idea, so this is merely an attempt to articulate it in my own way.

Technological progress is self limiting

The basic idea here is that as any creative civilisation approaches the capability of efficient interstellar travel it simultaneously approaches the capacity to destroy itself, along with the technology for efficient interstellar travel.  This places a limit on technological advancement well below what would be required for interstellar travel.  I won’t inventory the many ways that technological progress can destroys itself. but just offer three possibilities.

  1. Interconnections are necessary for advanced technology, but cause fragility Interstellar travel will require a great degree of coordination and interconnection.  This isn’t just cooperation between people, but the interconnection of energy production, communication systems, and labour.  Basically, we’ll probably rely on single interconnected systems more and more over time because they will be necessary to reach the productive efficiency required for interstellar travel.  The problem is that such interconnection makes civilisations more fragile to the effects of disasters.  A single failure in an interconnected system has larger effects on the system as a whole than the same failure in a decentralised and unconnected system.  Think of major financial collapses; big banks are more efficient, but when they fail, watch out.
  2. Production enhancing technology makes it easier for megalomaniacs to kill  I have written before on the consequences of ever increasing productive efficiency on human survival.  Productive efficiency boils down to how much labour is required to produce a product or service.  Interstellar travel will require a great deal of productive efficiency–much more productive than we humans have now, for example.  However, the downside of increased productive efficiency is that it increases the efficiency of everything–both good and bad.  This means that as a creative alien species increases productivity, they also make it easy for an insane megalomaniac among them to destroy their world.  Think of it this way: the scale of harm that an stone age insane megalomaniac could do was pretty limited.  Today, one insane megalomaniac can do a lot of damage, and megalomaniacs of the future will have even more efficient tools for destruction.  It seems inevitable that innovation in productivity would have a self-induced limit; any alien civilisation that develops technology for interstellar travel is simultaneously creating technology that enables an insane alien megalomaniac to destroy civilisation.
  3. Production enhancing technology evolves too fast for societies to adapt      This is kind of related to the above point, but is perhaps more speculative.  The idea is that social and biological evolution (whether natural or artificial) is a slower than technological innovation, and the result is that our societies have a hard time adapting to the technology we create.  Failure to adapt can produce limits on further innovation.  For one, it can create resistance against the technology, some minor and short lived (like the 19th century protests against motor vehicles) and some major and long-term (like current opposition to nuclear power).  It can also create conflicts between societies in possession of these technologies that impairs or even reverses innovation.  Lags between social/biological evolution and technological innovation slows down and eventually halts advancements in productivity, particularly those for which the benefits to humanity are not immediately clear–as could easily be the case in interstellar travel.


None of these arguments assume much about the nature of aliens or how they organise themselves.  The main assumption is that increasing productive efficiency is unavoidably paired with technological innovation.  That’s why I see this as a Marxist or neo-Marxist resolution to the Fermi paradox; changes in the modes and efficiency of production drive innovation, but also create conditions for destruction, resulting in a self-induced limit on all technological innovation.

Personally, this possible limit does bother me at all, as I have never been much of a fan of aliens or space travel and exploration.

A Poem

That night when I ceased to exist
(alternative title ‘After watching a season of Black Mirror’)

Late one night, I looked up from my phone
And noticed you’d been gone for a year
Though it was late, I texted a mate
To meet at the pub for a beer
He was then occupied, so another I tried
Somewhere down on my contact list
But my battery croaked, and my charger was smoked
That night when I ceased to exist

I turned on my desktop and clicked on my mouse
But the task bar showed no Internet
I jiggled the cable, ‘neath the dining room table
And tapped on the router outlet.
No signal arrived, and so I contrived,
That the problem required an assist
But with no means to connect, I became circumspect
That night when I ceased to exist

I went out the door to summon a cab
Waving my hand in the air
But the peer-to-peer hacks, were set in the tracks
All summoned by Uber elsewhere.
So I took to the street, on my desperate feet
Where the sidewalkers barely persist
But without GPS, I could hardly egress,
That night when I ceased to exist

I wandered for hours in the cold and the rain,
Not a soul could be seen on the street
The skyscraper light, obscured all the night
Among swarming of networks replete
In a virtual town, with no one aground,
I could find not a life to enlist
So I turned over my fate, to a cell phone update
That night when I ceased to exist