Quantum peep

PROF BOB CYWINSKI, Dean of Applied Sciences, University of Huddersfield


In recent years, the words “nanoscience” and “nanotechnology” have become part of our everyday language.

Just the other day I even saw a pair of socks with a label proclaiming that they were impregnated with odour-eating nanoparticles of pure silver.

Unfortunately, not too many of us know precisely what the prefix “nano” really means nor whether nanotechnology is actually good for us. Nano is an abbreviation which means one-thousand-millionth — or a billionth.

Nanoscience and nanotechnology aim to study, understand and develop materials on a length scale of approximately a nanometre — a billionth of a metre, or a millionth of a millimetre.

In order to imagine how small this really is, first of all consider that you are shrunk in size by a factor of 5,000.

At this scale, a dust mite would appear to be the size of a rhinoceros, a hair the thickness of tree trunk, and a grain of pollen the size of a tennis ball.

Then shrink by a further factor of a thousand. Now the electronic circuitry inside a silicon chip from your computer would look like a complex arrangement of interlocking walkways in a futuristic city and the smallest bacterium would be a metre in length.

Shrink by another factor of a thousand and you will have finally reached the nanoscale, where a single atom would appear to be the size of a beach ball, and a strand of human DNA over a metre across (and almost a million kilometres long!)

It is at this scale that the nano-engineer works, manipulating and arranging individual atoms and molecules in new ways to produce novel materials and devices with technologically important properties.

One of the principal reasons why materials behave so differently at the nanoscale is because this is where the laws of physics, which describe and explain our everyday experiences, start to give way to the weird and wonderful laws of quantum mechanics.

Quantum theory has now been with us for over a century, and though it describes a world that we can only just begin to imagine, it has survived, with flying colours, every single test that has ever been thrown at it.

Quantum theory describes a world in which particles, such as electrons, can also behave as waves and in which light waves can behave as particles, known as photons.

This means it no longer makes sense to talk about where a particle actually is, only about the probability of finding where it might be!

Also, unlike a squash ball bouncing off a wall, an electron hitting a barrier is just as likely to travel through the barrier as it is to bounce off, and a trapped electron could even tunnel through the walls that contain it.

All of these quantum properties are crucial to the electronic devices we use every day, including computers and mobile phones.

But nanotechnology enables us to fully exploit these quantum effects, to develop new, smaller and more powerful electronic devices, fast and sensitive magnetic read-heads for computer hard disks, electronic systems and devices based upon single molecules and ultra-fast quantum computers and methods of uncrackable encryption which make direct use of the underlying probabilities of the quantum world. Additionally, nanoscale materials can display considerably improved properties compared to their large-scale counterparts.

Nanoparticles can be readily absorbed through the skin, and therefore offer the potential for better medicine delivery.

They are also finding their way into cosmetics and sunscreens using, for example, nanoparticles of titanium oxide to effectively block harmful ultraviolet rays. Some nanoparticles are particularly effective antibacterial agents — hence their use in socks!

But it is these applications that bring with them the greatest concerns.

We do not yet fully understand what role nanoparticles will play in the environment.

The silver or titanium oxide particles that are washed from our socks or sun-tanned backs may travel through our water systems where they could do significant damage to the life in our rivers and lakes by destroying the bacteria that is crucial to the eco-system.

Nor do we yet fully understand the health implications of working with, or using, nanoparticles which are able to penetrate our skin and safety masks so easily.

On the whole, there is little doubt that small is beautiful — and indeed very useful in our increasingly technological society.

Equally, there is very little doubt that we should also proceed with caution when introducing new nanomaterials into our environment — at least until we fully understand what they are capable of doing.


Professor Cywinski, in collaboration with the production companies Optic Verve and Puppetman Productions, has made an animated adventure in which he takes a teacher and her two pupils down in size to experience the wonders of the quantum world at first hand. See it at www.thepocketprofessor.co.uk