Brian Clegg's Blog, page 148

Who are you calling a wave?

Ever wondered what light is? In 1905, Einstein boldly made the assumption that light came in the form of particles. This caught everyone by surprise, because if there was one thing everyone was certain about, it was that light was a wave.

To be fair, Isaac Newton had thought that light was a stream of particles, but by the start of the twentieth century this idea had been discarded. Thomas Young showed in a beautifully simple experiment in 1801 that light could produce interference patterns when it passed through a pair of narrow slits. Young was pretty versatile: he was a medical doctor, brought the concept of elasticity to engineering, produced mortality tables to help insurance companies to set their premiums and made the first partial translation of Egyptian hieroglyphs.

The mingled beams from Young's slits threw shadings of light and dark onto a screen, corresponding to the addition and subtraction of the ripples in light waves, just as waves interacted on the surface of water.  No other explanation seemed possible.

Scientists of the time could not comprehend how these patterns could be developed by a stream of particles. A particle had to follow a single path from source to screen. Passing particles through a pair of slits should result in two bright areas (one behind each slit) and large swathes of darkness, not the repeating dark and light patterns that everyone could clearly see when they carried out the experiment. Similarly, light, like waves, can bend around corners, a phenomenon called diffraction, while particles are limited to bullet-like straight lines.

So how was science to cope with this new discovery that light behaved as if it were a particle when it interacted with matter? The answer was to say that light had both wave-like and particle-like properties, a solution that is given the label wave/particle duality.

What's happening here is that scientists are building models. Not literal models like the ball-and-stick molecule models you might have played with at high school, but mental models. Simplified pictures of how something is. When we say light is a wave or it's a particle, what we really mean is that we're using the model of a wave or a particle to explain its behaviour. Light is like a wave or particle – but these are both big, human scale world things. In the quantum world, light is just light, but happens to have wave-like or particle-like properties.

Is if to underline the confusion, in 1924, the magnificently named Duke Louis de Broglie thought that if light particles could behave like waves, why not other quantum particles as well? He showed that electrons, normally considered particles, could also behave like waves, producing interference patterns like light through Young's slits, and being diffracted.

For me, if I need a single model of light it's particles every time. With quantum theory it's possible to explain all the wave-like behaviour in a special kind of particle. More to the point, we have the word of Richard Feynman, something of a hero to me as he is to many physicists. Feynman said:

I want to emphasize that light comes in this form - particles. It is very important to know that light behaves like particles, especially for those of you who have gone to school, where you were probably told something about light behaving like waves. I'm telling you the way it does behave - like particles.

Starring Apple TV

For a while now I've toyed with getting some sort of TV-internet integrating kind of box. I wavered when technology guru Dave Howkins commented how brilliant the Western Digital WD TV Live box was, but in the end I plumped for an Apple TV - but was this a good move? We'll see.

The idea of these boxes is to integrate internet content with your TV to make the UltimateViewingExperienceTM. Sounds like the kind of thing that's good in principle, but somehow never quite works.

So I forked out the not unreasonable £90 to £99 (depending where you buy it) for an Apple TV. First observation it's tiny. Ridiculously small. I've had power supplies bigger than this box. Still, whap in the cables and let's go (note, btw, it doesn't come with an HDMI cable, you need to buy one).

The outcome - I am genuinely pleasantly surprised. I can control the thing with the supplied (also rather small, but beautifully formed) remote, or an app on my iPhone or iPad. The main screen gives a very crisp menu with choices of Movies, TV Shows, Music, Internet, Computers and Settings (see left). Movies and TV Shows provide material from iTunes, so mostly paid for.


This has already come in useful, both to watch a fairly recent film, and to catch up on the TV series Whitechapel, which we only discovered in Series 3, but is available from iTunes. The basic video level is as good as ordinary TV/DVD, and HD is somewhat better.


Next up on the menus is Music. This is only of interest if you've paid up to Apple to have iTunes Match, which puts all your music in the 'cloud' so you can play it from any device, including Apple TV - works fine if you have this. Next a very useful 'Internet' section. This includes Netflix, which admittedly involves a £5.99 monthly subscription, but gives a great choice of older films and TV series (I have every intention of watching Morse through from Episode 1). You also get YouTube for the yoof, and provided your computer is running iTunes you can access your computer's music and photo library from the 'Computers' section.


One thing Apple TV doesn't have yet (but the WD box does) is an iPlayer option. But one extra feature available to those with iPads and iPhones is that you can turn on mirroring where anything playing on the portable device's screen shows on the TV. This is fun when you are showing people photos on an iPad (by far the best way to share digital photos) as they are also on the TV screen for a wider audience. But it also means you can use any of the catchup services - iPlayer and ITVPlayer, for instance - and mirror it onto the TV screen.


All in all - everyone loves it. The only problem is everyone wants to use it!

Don't go to Bicester!

We're lucky, living in Swindon having a designer outlet centre on our doorstep, but we thought we'd give the Bicester equivalent a try. What a nightmare.

I have never been in such a badly laid out car park. No indication how to get to the upper level, no idea if the lanes were one way (some people clearly thought so from 5 near collisions).

The 'village' itself has no maps up, just paper ones. And catering was ludicrous - vastly under supplied. You either queued just to get in or sat outside in the rain.

Ok the shops were ok (though I hate the way the staff keep speaking to you - if I want help I'll ask for it), but mostly too small and crowded.

Won't be coming here again.

The Germans are coming

One of the most enjoyable sidelines of having books published is that sometimes you get foreign translations. These tend to disappear into the ether, as there is inevitably a long delay while they get translated and then, with any luck, out of the blue, a copy of the translation drops on my door mat.

I say 'with any luck' as I'm still waiting for copies of translations of some business books from around 7 years ago. Sometimes the foreign publisher doesn't bother to send the requisite copies... but usually they do.

I've just had two of my popular science books translated into German. The first is Inflight Science, which has appeared with the impressively long title 'Warum Tee im Flugzeug nicht schmeckt und Wolken nicht vom Himmel fallen', which according to my rusty schoolboy German translates as Why tea is tasteless on a plane and clouds don't fall from the sky. Try asking for that in a hurry in Vaterstones.

The second one (which I haven't received copies of yet, but should do any day) was written in English several years earlier, but by coincidence is just coming out now. It was Before the Big Bang, but is now Vor dem Urknall - apparently this is the same (we didn't do Urknalls at school). I have to say, I rather like the cover.

I hope these go down well in Germany...

Over here and very welcome

I frequently give talks in schools, which makes a great break from writing, and is an experience I really enjoy. (If you are a school and want to know more, see the talks page on my website for full details.) It's not just a matter of getting away from a computer, unlike many people I get a real buzz out of public speaking. Doing this has taken me all over the country. But I was a little surprise to get an email asking me to speak to an American school class.

Not a bad venue for a school talk (but it was snowier today)My books sell pretty well in the US (one of my two main publishers is the excellent US publisher, St. Martin's Press), so I wasn't totally surprised to hear from someone over there, but I was all prepared to get back to them saying 'Sorry, but it's rather a long way to travel' when I read the email a little more closely. It seemed that the class from the Wakefield Country Day School of Huntly, VA was taking an educational visit to the UK. And their first night, en route to Bath, they were stopping over in Swindon. So I was delighted to be able to give my first US school talk, appropriate enough on Inflight Science .

The intention was originally to give the talk at the students' hotel, but it proved cheaper to hold the event at the nearby Lydiard Park conference centre, which is very near where I live - so not only did I get to talk to my most distant audience yet (for science - I've done Kuala Lumpur and Hong Kong for creativity), I didn't even have to get out of bed early to do it. After a minor panic caused by a fairly heavy snowfall overnight (which made Lydiard Park look great) it all went well. They were a lovely audience, if a little soporific after flying over yesterday, and it was good to meet the group leader Welby Griffin and the other adults with the party. All in all, an excellent morning.

Good science, bad science

Something I try to get in books and talks that an awful lot of people presenting science skim over is that science isn't about absolute fact. All science can ever be is our best guess given the current data. Tomorrow new data may emerge that totally overthrows our current thinking.

This has happened repeatedly in the past. Something like Newton's laws of motion can seem set in stone (hence the 'laws' label, which I don't think is a good idea). And then along comes Einstein and shows they are wrong. Not wrong enough to throw them away - they still work well in many circumstances - but wrong nonetheless.

This is why I get a bit irritated when popular science presenters and writers make sweeping statements like 'the universe began 13.7 billion years ago in the big bang.' What they should be saying is 'according to our best supported current theory, which fits the data well (though it's not entirely surprising as bits of it have been changed to do so), the universe began 13.7 billion years ago in the big bang.' Now, I admit that's rather clumsy - but I think every popular science book should have a proviso that what is being described as if it were fact is the current best theory, and this may change.

Note that this isn't an argument in support of the 'evolution is just a theory, so we ought to teach intelligent design' brigade. I didn't say a 'current theory'. I said the current best theory - the one best supported by the evidence and that works well with our other current best theories. This is not a recipe for taking any old hypothesis with the same confidence as the best theory. But it is bad science to suggest that our favourite theories (especially those like the cosmological ones which are based on very indirect data) are fact.

That's one kind of bad science. Another is cheating. We tend to think of scientists as emotionless seekers after the truth, but if you ever meet a scientist (treat them nicely - buy them a drink!) most are normalish human beings. With human tendencies. And there is a well established psychology of the way we fool ourselves in order to get the results we want. This inevitably happens in science. Some of the best known experiments in science have not really produced the results the scientist wanted. So they just went ahead and ignored the results. Newton, for instance, didn't get what he really wanted in his experiments with light using prisms. No matter. He knew the desired result and that's what he wrote up. Whenever anyone writes about general relativity, they talk of Eddington's 1919 Principe expedition which proved the expect effect of the Sun bending light. Only it didn't - certainly not within acceptable margins of error. But Eddington announced the result he wanted.

It would be silly to think that this doesn't happen all the time, and I'm delighted to be able to show the graphic below (technically an 'infographic' but I hate the term) from Tony Shin and his team (I've seen it elsewhere, but it's worth repeating) on the subject. I ought to say that we shouldn't take this as all bad. Many experiments are't fiddled. Just because a result is tweaked doesn't mean it's wrong. And over time science's system of repeating results ensures that problems are ironed out. But we can't pretend it doesn't happen:

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Created by: ClinicalPsychology.net

So good they named him twice

I get plenty of unsolicited emails because my email address is publically available on a website. I don't mind too much because just occasionally amongst the dross I get an email that gives me so much pleasure that it's worth the drudgery of sweeping away the rubbish. And one came today.

The image to the right is the opening of the email. In it we learn that William O'Connor (I presume that is he in the photo):

boasts over 30 years in active mediumship and psychic consultations with a wide array of achievements including TV and Radio. William has been active in the spiritualist movement in Scotland for many years not to mention psychic floor shows in front of large audiences.

What's more:

William and his psychics will be at the Body & Soul Fair at Glasgow Royal Concert Hall on 25th and 26th February. Our psychics will be available to provide private readings, 20 minutes for £30.
Demand is sure to be high so book your reading now, for a time which suits you!

Just in case you get too excited, though, I ought to point out that your psychic reading on the phone is not by the psychic psychic himself, but instead you will be connected 'to a psychic who is fully trained and mentored by William O'Connor.' A sort of homeopathic psychic.

I was going to every so slightly poke fun at this email, but really I don't need to. It does the job without help. Similarly I had considered putting in a proviso that by mentioning this, I in no way endorse it, because in my opinion some psychics are frauds, some are totally genuine in their belief but deluded - but to be honest I don't need to do that either. I trust too much in the intelligence of my readership. Instead, then, I intend to roll about the floor laughing at the concept of a psychic reading taking place on a meter at 80p a minute. Exuse me while I ROFL.

Ah, vanity

Every now and then, when I've nothing better to do, I examine the backs of cosmetic bottles and other gubbins that are found lying around the house. (Yes, this is the kind of exciting life a science writer has.)

What I see on the back of some of those bottles is a mystery to me. Actually, a number of mysteries.

Mystery #1 is why some products have a contents list and some don't. The fact that some don't seems to imply it isn't required. So why do it at all? (It could be it's specific products, or it's on the cardboard box instead. Dunno.)

Mystery #2 is who do they think they are fooling with 'aqua'? Pretty well all cosmetic bottle contents have water as their number one ingredient, but the manufacturer seems to think that they can make it sound more impressive by calling it 'aqua'. Only they also seem obliged to give the game away as it is, in fact, always called 'aqua (water)'. So why bother with the 'aqua'? It just makes you seem silly, guys.


Mystery #3 is how a particular company making the product seen above (and for all I know many others do this also) managed to make themselves look even more stupid. Because the next entry is wonderfully bizarre. It's 'Paraffinum liquidum (Mineral oil)'.

Okay, let's break this down. Firstly 'Paraffinum liquidum' sounds more like a rather bad Harry Potter spell than an ingredient. Secondly, it doesn't take a classical education to work out that 'Paraffinum liquidum' is liquid paraffin. You know, that stuff your granny used to put in her portable heater. Actually, a classical education is the last thing you want here. Admittedly 'liquidus' is the Latin for liquid, so they were quite close there, but 'paraffin' is not taken from a Latin word so this is pure pig Latin.

I can see they realize people wouldn't want to know that they are coating themselves in paraffin, but this hardly conceals it, does it guys? They would have been better off sticking to the much more natural and friendly sounding 'Mineral oil' (it must be good for you, it has minerals). Admittedly all this means is something extracted from crude oil - technically petrol and diesel are mineral oils - but it sounds so much better.

So there we have it. Is there a sillier contents label? Almost certainly. But I am yet to find it.

Loving Yasiv

Occasionally someone will come up with a web app that hasn't got any real benefit in life, the universe and everything, but that's great fun. And surely this is not a bad thing.

Thanks to @thecreativepenn for pointing out Yasiv.com. Put in a product listed on Amazon.com and you will see a diagram of related purchases.

The developer sees this as being a good way to think 'if other people bought this as well, then perhaps I should look at these too.'

But also if you happen to have produced a product that's sold on Amazon, then it is rather fun to take a look at these 'related' products and what other things people bought. It doesn't just apply to books - you can do it with anything on Amazon.com (though not at the moment .co.uk - I emailed the developer to ask, and it's on his to-do list). Give it a try...

Antimatter apples

I had a lovely time on Wednesday evening giving a talk based on How to Build a Time Machine at Pewsey Library. I don't know what it is about Pewsey, but this is the second time I've spoken there, and again we had some brilliant questions, which tend to range over all of physics.

A couple were on gravity, which is rather nice as it's the subject of my next St Martin's Press book, due out later this year. And one was particularly timely. Someone asked, given that both electricity and magnetism have positive and negative aspects, was there anything that repelled gravitationally, rather than attracting.

It's timely because an experiment is underway to try to determine whether antimatter is gravitationally attracted by matter or repelled by it. I had always assumed antimatter was just like ordinary matter, behaving exactly the same way in everything except its electrical charge. So I was quite surprised when reading a book by George Gamow on gravity that he suggested it might be repelled gravitationally by ordinary matter. When a scientist of Dr Gamow's stature suggests something, you take it seriously.

You might think this is trivial to test, but it's not. Firstly we've only got tiny amounts of antimatter - and it doesn't usually stay around long before annihilating with normal matter. And also gravity is a very weak force. It might not seem it if you try to jump off the Earth, but just think about it. When I hold a fridge magnet near the fridge and let go, it has the whole Earth pulling it downwards and just a tiny magnet pulling it towards the fridge. The magnet wins. Gravity is vastly weaker than electromagnetism, making it very difficult to detect and distinguish gravitational effects in tiny particles of antimatter.

It will be fascinating to find out which way the antimatter goes. Apart from anything else, it has an implication for the principle of equivalence. This was what inspired Einstein towards general relativity, his theory of gravitation. The idea of equivalence is that if you were in an enclosed spaceship with no connection with the outside world, at any point in the spaceship you couldn't tell if you were feeling a gravitational pull or being accelerated by the ship's motors. The effect would be identical. They are equivalent. But if you had a piece of antimatter, and it is indeed repelled by ordinary matter, you would be able to distinguish. It doesn't really matter for general relativity, but it would mean a proviso had to be inserted into equivalence.

Let's wait and see. I rather hope the antimatter is repelled by matter. After all, it would make the universe even more exotic.