A few years ago I was set the challenge of explaining quantum physics to the then BBC broadcast journalist Robert Peston in 5 minutes. In practice, of course, this is a pretty much an impossible task, but the idea was to give a quick taster - which I hope it does.  I've written quite a bit on quantum physics, if it's something you'd like to dig into a bit deeper: The God Effect - exploring quantum theory's most mind-boggling concept, entanglement with implications from teleportation to unbreakable encryption Cracking Quantum Physics - an illustrated beginner's guide to the quantum world The Quantum Age - focuses on the applications of quantum physics that have transformed our world Quantum Computing - how computers making use of explicit quantum effects have the potential to run algorithms that perform in ways impossible to duplicate with conventional devices. Here's that video: These articles will always be free - but if you'd like to support my onlin...

REVISIT SERIES: A post from July 2012 -  Science isn't always great at naming things. For every photon there are plenty of clunky names that don't do a lot for you. Take, for instance,  the 'principle of least action', which sounds like a description of the lives of teenagers. This is a shame because it is really interesting. For reasons that will become clear I like to think of it as 'the Baywatch principle.' And what it says, in essence, is that nature is lazy. French mathematician Pierre de Fermat used the principle of least action to explain why light bends as it moves from a thinner to a thicker substance (from air to glass, for instance) – and Richard Feynman made it a fundamental part of quantum electrodynamics. The principle of least action describes why a basketball follows a particular route through space on its way to the basket. It rises and falls along the path that keeps the difference between the ball’s kinetic energy (the energy that makes it mov...

I'm very pleased with my new book  Cracking Quantum Physics . It's a chunky, beautifully produced, heavily illustrated little book, designed to give beginners an idea of what quantum physics is all about. In over 300 pages, mostly in easily digestible two-page spreads, it covers everything from our first thoughts about the nature of matter through to possibilities for quantum gravity. One thing I do need to address, as it has already caused John Gribbin to raise a sarcastic eyebrow is the sub-title 'You, this book and 200 years of sub-atomic science.' This book is part of a series of 'Cracking' books (Grommit) and they all have this kind of format in the subtitle, for which the author has no input. I sort of get what the 'you, this book and...' bit means, even if it is a trifle cringe-making, but the part John was surprised about is '200 years of sub-atomic science.' What could this possibly refer to? Arguably the first definitive sub...

When I wrote T he God Effect about entanglement around 10 years ago it seemed that many of the remarkable possibilities that emerged from this strangest effect of quantum physics were close to practical applications. As it happens, there's nothing in the book that's gone out of date - but we do keep getting incremental announcements in the field. Most recently we had the more over-the-top media sites telling us 'Scientists teleport bacteria' while the more careful phys.org came up with the confusing sounding 'Physicists propose the first scheme to teleport the memory of an organism.' I'd need a whole book to go into quantum entanglement (:-)), but the summary version is that quantum physics predicts that, for instance, you can get a pair of quantum particles into an entangled state where making a measurement of a property of one (its spin, for instance) will instantly influence the other particle, however far apart they are. And this has been experiment...

Image © EPFL 2015 We have a report from the Ecole Polytechnique Federale de Lausanne (EPFL) of 'a photograph of light as both a particle and a wave.' HT to Ian Bald for pointing this out - the paper dates back to March, but I didn't spot it at the time. It's interesting to dig in a bit and see a) is this true and b) is it the end of Bohr's assertion as part of his concept of complementarity that light could act like a wave or a particle but never both at the same time? The experiment is complex enough that it's a little fuzzy when it comes to the interpretation. What the experimenters did was reported by the EPFL's press people as follows. The experimenters fired a laser at a metallic nanowire. Some of the energy from the photons in the light stimulated electrons in the wire, which meant that 'light' travelled along the wire in two directions. When these waves met they formed a standing wave which generated emitted light. They then shot elec...

I dedicate a fair chunk of my book on the way that quantum physics is transforming our world, The Quantum Age , to superconductors. These remarkable substances with no electrical resistance and impressive magnetic properties are already supporting a range applications from MRI scanners to maglev trains, but what is always described as the 'holy grail' of superconductivity is a room temperature superconductor. The earliest examples had to be cooled within a couple of degrees of absolute zero (-273.15 °C), and even now they need either liquid helium or liquid nitrogen, depending on the type, to keep them cool enough. This is okay for specialist applications, but means they can't break out into everyday everywhere use. But if a superconductor could work easily at room temperature it would transform electronics and electrical products everywhere. Hence the excitement whenever a new temperature high is announced. This happened recently when the simple compound hydrogen sul...

I spent a nervous few minutes this morning in the BBC's Swindon NCA studio, connected down the ISDN line (remember ISDN) to London to appear on the UK's flagship current affairs radio programme, Today , being grilled by the inestimable John Humphrys. Thankfully he didn't want to ask me about David Cameron's performance so far, or the antics of Sepp Blatter and friends, but instead we talked about my book The Quantum Age , which is out in paperback today. It has quickly become a favourite of my output, both because I love the weirdness of quantum physics - and I have fun exploring that - but also because few of us really think about the impact that quantum physics makes on our everyday life. At a trivial level, pretty well everything is down to quantum physics, as matter, light and electricity (to name but three essentials) are all quantum based. But there is a more significant reason for calling this the Quantum Age, just as the nineteenth century was the Stea...

One reaction to my writing The Quantum Age is that the number of emails I receive based on a sort of 'quantum mysticism' has doubled. This is where the jargon of quantum theory is applied recklessly, without any of the background science, to imply that something strange and wonderful can happen... because it's 'quantum'.  I recently had this article on the website of the 'Committee for Skeptical Inquiry' with the same name as my current post brought to my attention. It is rather dated, as it was written 17 years ago, but much of it holds up. A lot of blame is laid at the door of Fritjof Capra's popular book, The Tao of Physics ,  which draws parallels with aspects of quantum theory and Eastern mysticism (though to be fair to Capra, he doesn't the extra step, made by many New Agers, of going from parallels to assumed causality). The author of the CSI piece, Victor Stenger, is very blunt in his dismissal of anything mystical, if not mysterious,...

The British physicist/astronomer, Arthur Eddington was a great science populariser who came up with a lovely comment when writing about quantum mechanics in the late 1920s. He wrote that rather than cover the theory as it stood, he really ought to 'nail up over the door of the new quantum theory a notice "Structural alterations in progress - No admittance except on business". And particularly to warn the doorkeeper to keep out prying philosophers.' I don't think I've seen such a brilliant summary of the way quantum physics went through a transformation from its early implementation, and brought what many physicists would continue to consider far too much agonising over interpretation and philosophy into the field. I think it's fair to say that the notice has come down, but whether those philosophers should have been allowed in is a different matter.

Quantum physics is famous for its strangeness. As the great Richard Feynman once said about the part of quantum theory that deals with the interactions of light and matter particles, quantum electrodynamics: I’m going to describe to you how Nature is – and if you don’t like it, that’s going to get in the way of your understanding it… The theory of quantum electrodynamics describes Nature as absurd from the point of view of common sense. And it agrees fully with experiment. So I hope you can accept Nature as she is – absurd. It's interesting to compare two of the strangest concepts to be associated with quantum physics - Dirac's negative energy sea and the 'many worlds' interpretation. Each strains our acceptance, but both have had their ardent supporters. Dirac's 'sea' emerges from his equation which describes the behaviour of the electron as a quantum particle that is subject to relativistic effects. The English physicist Paul Dirac discovered that his...

Every now and then someone sends me an interesting question about science, and, while I can't guarantee to answer it, I do my best. I got one yesterday that said 'if light can be considered traveling in packets, what is between those packets? Does anything exist (in the space) at the end of one photon and the beginning of the next photon?' And this a particularly engaging question, not so much for the answer, which is pretty straightforward, but for the implications it has for the way we talk about physics. The answer, to get it out of the way, is nothing. There is nothing (in terms of the light itself) in between photons or between the 'end of one photon and the beginning of the next' - apart from anything else, photons don't really have 'ends'. A beam of light can be described as a set of discontinuous particles we call photons and there is no more something between them, linking them, than there is amongst a stream of electrons. Yet that's whe...

Large prisms used in a tunnelling experiment In theory, science is very flexible. It is the absolute opposite of a rigid, fundamentalist religion, because there are no absolute truths in science. Theories are just as good as the evidence available - and it's entirely possible that evidence will come out tomorrow that make a widely supported theory untenable. However, scientists are also human, and have a tendency to cling on to favourite theories beyond their sell-by date. It's not that they go into fundamentalist mode and ignore the evidence - they are more flexible than that. But they will change and patch up a favoured theory so that it matches the latest data. A good example is the big bang theory, which has been patched several times as new data emerged. (And may need patching again if it turns out that inflation wasn't really the way we used to think.) This is not surprising, though it can be arbitrary in the short term. The great British astrophysicist Fred Hoy...

One of the joys of writing a book like The Quantum Age (still just 99p on Kindle) is discovering new and interesting things - and one I particularly enjoyed was the deployment of quantum technology to deal with sewage. Finding superconductors in powerful electronic devices and scanners may not be too much of a surprise, but a surprising example of an application of superconductivity - a totally quantum phenomenon -  is a million miles away from the delicacy of Josephson junction powered SQUIDs (Superconducting Quantum Interference Devices). It is in sewage treatment. We live in a paradoxical world that is awash with water – it almost defines our planet – and yet at the same time where there is a shortage of clean drinking water. It shouldn’t be that way. The world contains around 200,000,000,000 litres of water for every living person. If you think of that in terms of consumption, assuming a typical 5 litres a day, the water out there should last over 100 million years. And ...

Here's the thing - I'm very pleased with my new book The Quantum Age . It combines the weird and wonderful nature of quantum physics with an exploration of remarkable quantum applications, from lasers to superconductors, and the stories of the development of these ideas and technologies featuring some big (and sometimes decidedly strange) characters. The Kindle edition usually sells for about £8.99, but as part of their 'Summer Reads' promotion, Amazon currently has it at 99p ($1.69) - because why wouldn't you want to read about something as mind boggling as quantum physics on the beach? Being a Kindle ebook, you can read it on a Kindle device, but also on tablets, smartphones, laptops, the better kinds of abacus* - so there's no excuse. You are probably thinking, yes, but I don't want to deprive Brian of income. Don't worry - I really do want you to get a copy. Leaving aside the fact that not everyone would buy it at full price, if enough of you d...

I'm delighted to say that my new book, The Quantum Age is now available - see it's web page for details or to buy. The premise is simple - we have had everything from the stone age to the steam age, but now we're in the quantum age, where quantum-based devices are everywhere (there at least seven different quantum technologies in a smartphone). The book combines an explanation of the basics of the science with the remarkable stories of the development of different applications from basics like electricity, through the natural world of quantum biology to lasers and superconducting magnets. As a taster, here's the introduction: The chances are that most of the time you were at school your science teachers lied to you. Much of the science, and specifically the physics, they taught you was rooted in the Victorian age (which is quite probably why so many people find school science dull). Quantum theory, special and general relativity, arguably the most significant fu...

As, for obscure reasons, I am replacing Roy Hattersley at the Kempsford Literary Festival and talking about Build Your Own Time Machine (if you're interested it's in St Mary's Church, Kempsford, 4.30pm on Sunday 27 April, £5 - tickets from kemplitfest@gmail.com or on 01285 810588, or on the door), I thought I'd do a quick time travel related post here. As I describe in the book/talk, there is nothing in the laws of physics that prevents time travel, and relativity makes forwards time travel relativity simple. Backwards is a lot more tricky, but in principle this is possible using general relativity effects. But many physicists believe that it can never actually happen, in part because of the paradoxes that arise if you can travel into the past. The best known time paradox is the so-called grandfather paradox, where you visit the past, kill a grandparent before you are born (I don't know why it's a grandparent, but it's traditional) and you're in ...

After the shoot A couple of weeks ago I had the very enjoyable experience of spending a couple of hours in the company of the BBC's business editor, Robert Peston. In a series of five short pieces, Robert has been finding out more about a number of things that have fascinated him but eluded him over the years. He has learned to do Punch and Judy, to paint a landscape and to order his Chinese takeaway in Mandarin. And I had a go at teaching him quantum physics. We met at the Science Museum Library at Wroughton near Swindon, a location I had suggested as a good sciencey backdrop. Although it was a bit slow going as anything with a camera involved tends to be - and I'm rather sad at just how much as ended up on the cutting room floor - I think it went pretty well. See what you think:

Randomness and probability are at the heart of my book Dice World and they are also fundamental to quantum theory, which is why I spend some time on the subject in the book. One of my favourite aspects of quantum theory is quantum entanglement (I wrote The God Effect on the subject), which is responsible for a number of interesting technical developments including a small-scale version of the Star Trek transporter. Think for a moment of what’s involved in such a technology. On Star Trek , the transporter appears to scan an object or person, then transfers them to a different location. This was done on the TV show to avoid the cost of the expensive model work that was required at the time, before the existence of CGI, to show a shuttle landing on a planet’s surface. But it bears a striking resemblance to something that is possible using entanglement. To make a transporter work, we would have to scan every particle in a person, then to recreate those particles at a differe...

It's appropriate that the episode of The Big Bang Theory I watched last night featured as part of a kind of nerd Olympics a competitive game of Where's Wally (or to be precise, the US variant of the book  Where's Waldo? - why did they change the name?) where contestants were handicapped by playing without their glasses. There's something very Where's Wally? like about my topic today, which is the puzzle of where a quantum particle like an electron or a photon is when you aren't looking at it. Here's the thing. Unless you observe it and pin it down, a quantum particle's location is fuzzy. The position is described by Schrödinger equation, which tells you the probability of it being in any location, but this isn't like saying I can give a probability for where I am in the house, because in practice I actually will be in one, specific place at any one time. In the case of the quantum particle the probability is all there is. The best we can say is...

The title of this piece may sound like the latest Young Adult bestseller (and I reserve all rights, thank you very much) but I was thinking of something a little more down to earth... yet at the same time rather more exciting. Even though it has been out for a while, I get more emails about my book on quantum entanglement, The God Effect  than almost any other. I think it is because the subject is mind-boggling even to physicists (the whole business really started when Einstein wrote a paper to the effect of 'this entanglement stuff is so weird, quantum theory must be wrong'... but it was Einstein who was proved to be in error), and because some of the applications are amazing, notably quantum teleportation, which produces an effect like a Star Trek  transporter on the scale of quantum particles. I just thought I'd give a taster for the subject by using a little extract from  The God Effect  where the scientists head for the sewers: By 2004, [Anton] Zeilinge...