The Amazing Brennan B2

My new toy, a two Terabyte Brennan B2 digital music player arrived this week:

It’s a fascinating piece of kit. Slightly bigger than half a dozen CD cases, it will hold 4400 albums using lossless compression. It exposes a web interface so I can control the player from any browser – laptop, iPad or phone. The amplifier delivers 35 Watts into my bookshelf speakers but it also has a fibre optic digital interface to connect to a real hi-fi set-up.

First impression: already excellent but with huge potential for more. Sound quality – even through the built in amp and my cheapo Gale speakers –  is very acceptable (I didn’t buy the Brennan speaker offering). The menu system is basic but it does the job. Control of playback through the web-site gives you a manageable interface to a cupboard full of CDs.

Still too early to say what it can’t do – for example, I haven’t been able to find all the functions of the built in menu in the web interface – but it does currently have some limitations; or should I say potential for improvement. For example, the built in amplifier has no tone controls to compensate for the characteristics of the room or speakers. Solution: that separate high end power amplifier. It’s also quite slow at ripping and seems not to be able to play CDs while ripping them. That isn’t really a problem as one can quite easily rip on a computer and then transfer the data to the Brennan on a USB drive.

It’s also clear that some of the acknowledged limitations can be addressed in future (downloadable) software releases. My own personal wish list would include improved navigation in the web interface and the ability to stream music over the local area network – with an appropriate piece of hardware to connect traditional amplifiers to WiFi. I’d also like to see what materialises when Martin Brennan delivers his improved support for ripping vinyl.  

In summary, though, this is the device we’ve all been looking for to provide hifi quality storage and management for the CD collection; already great, as is, and still a lot more potential.

Take a look at http://www.brennan.co.uk/

If no-one else really understands this then why worry it might be rubbish?

Of course, if one is going to think about quantum mechanics in ordinary terms, there is a sense in which failure is inevitable. It’s probably impossible to stretch everyday experience to cover something this strange.

At the same time, this shouldn’t necessarily be discouraging. After all, even the most esoteric mathematical models of these phenomena are clearly incomplete. There’s a point where they don’t join up with relativity, Newtonian physics and so on. So we can expect our own models to run out of steam – probably even more quickly – but that doesn’t mean they can’t be used as stepping stones towards some sort of understanding.

Following on, for instance, from the idea of propagation as a wave / interaction as a particle, is the question of what the wave is like. We actually know quite a lot about the particle – after all, that’s what we can measure – but very little seems to have been written about the wave.

One possibility is that the wave is pure energy. The particle converts to energy as it travels and then, when it interacts with something, turns back into its expression as a particle. That’s in contrast with the idea (courtesy of Schrodinger and Feynman) that we can think of particles as interchangeable and simply disappearing at one location and then appearing again instantaneously somewhere else[1] with the probability of appearing at any specific location being given by the interaction of probability curves modelled as sine waves.

In the supposition I'm thinking of, the process is like a soap bubble. It radiates outward from its source, expanding as it goes, as long as it doesn’t encounter anything it can interact with. As long as it is in this phase of propagation it exists purely as a wave of energy. This could last a very long time, think of a photon that left a star early in the life of the universe and has travelled for 14 billion years before it’s detected by a telescope. When it interacts with something, it reverts to being a particle.

At that moment, since the particle needs a fixed quantum of energy, the bubble bursts and all the energy becomes concentrated at the point of interaction. The rest of the wave front would necessarily disappear and this could be thought of as having an instantaneous impact elsewhere – possibly a way of accounting for so-called quantum entanglement.

Returning to the two slit experiment, this provides a second question that could be used to check whether this idea has any validity:        

• ·         If a detector is placed to observe particles passing through just one of the slits then particles it detects would be distributed as particles. Entities which are not detected (i.e. the 50% of cases going through the other slit) would continue to show an interference pattern.

Another interesting question is what constitutes interaction. Clearly if a photon (for example) is absorbed by an object of the right colour that constitutes interaction. What about one that is reflected from a mirror? Or one that is refracted through a prism or diffracted by the edges of the slits in the double slit experiment.

This all sounds as if it fits with the facts. Subatomic entities, when they propagate cannot be detected without turning them into particles, that is, they aren’t detected as waves, but they behave as waves when confronted with the double slit. When they interact as particles, their wave-nature disappears and they interact at defined points. Nevertheless, their wave history determines where they are observed. The outcome is, to an extent, random because it is a function of the interaction that transforms energy to particle rather than something inherent in the transmission.

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[1] ‘…the particle hops off to anywhere and everywhere else in an instant.’ The Quantum Universe: Everything that Can Happen Does Happen p. 46 Brian Cox and Jeff Forshaw.

Is it possible to think about quantum physics?

Quantum physics is at the frontier of understanding. One of the great unanswered questions is the search for a unified explanation of things at the subatomic scale and the behaviour of the universe that we perceive with our senses.

 At the same time, the tools that physicists use to investigate and think about this problem are so expensive – think of the Large Hadron Collider – and so esoteric – the most advanced mathematics – that ordinary people like me struggle even to understand the problem. If one can't think about quantum phenomena in terms of the large scale world, how can they ever be joined up? Can one, indeed, even think about this without the advanced mathematics?  That is the challenge.

One needs to start from the beginning with the two slit experiment that led people to believe, for a hundred years, that light was a wave. It showed that when light passed through two narrow slits it didn’t behave like a succession of particles. It showed interference patterns like those where the crests and troughs of two waves cancelled each other out.

It was only early in the twentieth century that a more sophisticated version of the experiment showed that light actually traveled as discrete particles – photons – and that, if one monitored which slit individual photons passed through, then the interference patterns disappeared. This is really strange but there’s no point in my spending a lot of time explaining this because YouTube already has many excellent videos on the subject. Take a look at Jim Khalili (shorter) and Richard Feynman (an hour) doing the honours.

My take on this is:

1. Photons, electrons, atoms etc have some characteristics of particles and some of waves.
2. When they are observed they behave like particles
3. When not observed, two slits are treated as a wave treats them and generate interference.

Which takes one back to de Broglie (cited by J S Bell [1]) who, ‘in 1926 … answered the conundrum wave or particle by wave and particle’. The wavelike aspect, however, is always inferred. All observations end up being of particles. Whenever quantum entities interact with anything, the wave seems to disappear and only the particle remains.

Perhaps the answer is that quantum entities propagate as waves but only interact as particles.

This seems to me an interesting thought, especially in relation to the idea that quanta have fixed sizes because, as soon as an interaction occurred, the whole quantum of energy in the entity would have to be localised so the wave would immediately have to disappear. As soon as the entity interacts, its potential to be somewhere other than the point of interaction expires. So measuring the exit of an entity at a slit would immediately remove any residue that might emerge from the other slit to interfere with it positively or negatively.

This interpretation generates a prediction which may well have been tested already:

• In the case where the entity has been identified coming through one or other slit, it would continue on its way as a wave so it would be possible to pass it through a second pair of slits and show an interference pattern on the other side. 

It also allows us to think about the probabilistic nature of quantum mechanics. One can think of the characteristics of the particle as not being determined purely by the entity itself but as characteristics of the interaction. A spinning coin is neither heads not tails until it lands on the table. Similarly, the spin (for example) of the resulting particle is not in the wave but emerges as it interacts with the external world. So no amount of knowledge about the earlier state of the entity would enable its prediction and no need of an ‘intelligent observer’, just an interaction.

[1] Speakable and unspeakable in quantum mechanics – J S Bell (1987) p. 171 

Risk Management

On Wednesday we had a presentation from Alan Matcham of the Leading Edge Forum on alternative organisational models, including a reference to a Dutch town that had abandoned traffic signals. By coincidence, a friend forwarded the attached video, entitled 'Why Roundabouts?' which arrived this morning.

I guess that this is really a question of risk management. I suspect that even the Dutch mayor who got rid of his road signs might have been a touch uncomfortable here. Ironic that we are not prepared to accept short term risk but live quite comfortably with climate change...