Of course Why Is It So? is quite an old vintage as television programs go, besides which the egg in the bottle experiment doesn’t appear in any of those clips. Members of my generation (X, in case you were uncertain) probably know the demonstration better from a series of Cadbury chocolate commercials in which Julius appeared in the 1980s – a cunning move, and proof that he was ready to spread the word of science in any way possible! Perhaps I should be seeking that road to success?

Anyway, it’s a classic, and I was genuinely excited to peform it again; it formed a brief part of my first solo science show, Listen to the Man in the Lab Coat in 2004, and served as an encore to my Comedy Festival debut, Science-ology, in 2007. Not having performed it for three years made it just as much a treat for me as for (hopefully) the audience – and given that some of them had never seen it before, I think I picked just the right “science trick” for the crowd. I hope to get some video of my demonstration and put it up here in the near future, but in the mean time, here’s a basic run-down.

First, you need a bottle – it used to be easy to get glass milk bottle, but now they’re a bit of a rarity in Australia. So much so I brought one back from my trip to New York, from the Milk Thistle organic dairy farm. (I’m aware that recent articles say there’s no nutritional benefit to organic farming, overturning previous research, but there are still other advantages, not least the taste. But I digress.) You can find glass milk bottles locally, though, and I recommend you do; other bottles can do the trick, but milk bottles have the perfect sized opening.

Next, you need an egg. The egg should be too big to fit in the bottle, and the larger the better; I used “XL” size (free range) eggs, about 60g each. There are some misconceptions about the egg; I’ve had a number of people complain that they always thought the egg was raw, but it’s always been a hard-boiled, shelled egg for this experiment. (You could try a raw one, and probably get a cool result, but an exploding raw egg is much messier. Actually, now I really want to try that…)

Finally, you need some paper and matches. This is the dangerous bit, so allow me to put in an obligatory warning: don’t do this at home without adult supervision, kids.

Okay, so the egg is too big to go in the bottle, right? How to get it in without mashing it? Set fire to a small strip of paper, drop it in the bottle, then put the egg back on top. After a short time, the egg will be magically “sucked” in to the bottle with a very satisfying pop! How did this happen? Or rather: why is it so?

I have to explain, of course, because that’s the primary difference between a science trick and a magic trick: there’s no scientist’s circle making sure I never explain how it’s done, and in this case, it’s all done with pressure.

(Sometimes someone claims the explanation is “Bernoulli’s principle”, and technically that’s accurate in some sense, though Bernoulli’s principle is specifically about the relationship between a fluid’s speed of flow and its pressure; an aircraft wing is a better example of that.)

So what happens to the egg? First, the flame heats up the air inside the bottle; since this causes the air to expand, there is a greater volume of air than can fit inside, and some of the air escapes by pushing past the egg. (You can often see this if you put the egg on quickly after dropping in the flame; it bounces up and down making farting noises.) Once the flame goes out – not because it has “used up all the Oxygen”, by the way – the air begins to cool, and as it cools, it condenses, decreasing in volume. There’s now a lesser volume of air in the bottle than is needed to fill it, creating an area of low pressure. The higher pressure air outside the bottle exerts a force on the lower pressure air inside – not enough to break the bottle, of course, but enough to push the egg inside until the air can get in and equalise the pressure.

So that’s it! I use a big egg to get a good noise, which means it can’t be extracted easily, though you should be able to do the experiment in reverse by holding the bottle upside down with the egg near the opening and either heating the air inside (to make it expand) or blowing extra air into the bottle past the egg. My eggs are usually too big for this method to be reliable. If you want to get really fancy, you can soak the egg in vinegar without taking the shell off, which makes the shell soft; once you get the egg inside, it will eventually harden, and that’s pretty impressive. If you don’t want tell-tale signs of burnt paper inside the bottle, you can either heat up the air by immersing the bottle in really hot water, or directly reduce the pressure by immersing the bottle in really cold water, which are less reliable and less impressive, but still work.

So there you have it: the egg in the bottle. If you’d like to see me do it, along with all the witty banter I’ve developed, by all means get in touch – consider me available for weddings, parties…anything!

It was only about 160 years ago that many people were still not convinced the Earth rotates on its own axis. After all, we don’t feel the motion; the Sun, Moon and stars seem to wheel around us, we don’t spin around like a top. Otherwise we’d get seasick on land, surely? Even when it became fairly common belief that the Earth orbited the Sun, the idea that the Earth also spun didn’t have much going for it. What’s to keep us from flying off?

We can be all superior about it now and talk about how the attractive force of the Earth’s gravity is far stronger than any angular momentum we might experience from it’s spin, or about frames of reference, or anything else, but we wouldn’t all have such concrete knowledge of these ideas without the work of Léon Foucault.

No relation to the philosopher and historian Michel Foucault, the physicist Jean Bernard Léon Foucault achieved all manner of great things: he measured the speed of light (with pretty good accuracy, much better than his predecessors), vastly improved the quality of telescopes, and named the gyroscope. But his most famous invention was a large, free-rotating pendulum, suspended in the Panthéon, which slowly changed the direction of its oscillation as the Earth rotated.

Many other such pendulums have been built, and I saw one when I was a boy, set up in the Queen Victoria Building in Sydney. I remember being quite obsessed with it at the time, reading up about its significance, enjoying the rich history of the same experiement being carried out over more than a century and across vast distances. I didn’t know it was only a temporary exhibit until I tried to find it on a trip back to Sydney in 2008, but I relived the joy when I saw another one in operation late last year at the Boston Museum of Science – suspended over a Mayan calendar!

Even the pendulum in the Panthéon was not Foucault’s first, but it was this one that caused a sensation in both scientific and lay circles – and which was irreparably damaged in May. Imagine it in the context of the time: a definite, physical demonstration of the Earth’s rotation! Today, a comparable feat would be to set up a simple demonstration  showing direct evidence of anthropogenic global warming. It’s easily possible to show that even a small amount of CO2 causes an increase in temperature – the wonderful Intelligent Life Magazine recently ran a great article showing you how – and perhaps building such a demonstration in public would silence some of the critics, but it’s hard to imagine it having quite the same impact as Foucault’s simple and elegant experiment did back in 1851.

There’s still a pendulum in the the Panthéon, a replica of the original, and given that party-goers at the Musee des Arts et Metiers had previously pushed the pendulum around, perhaps it’s better to go see the replica. That’s the wonderful thing about science – and indeed art: you might destroy the artefact, but the idea lives on. And if you really want to see a pendulum in action, you can find them all over the world.

Two of my most treasured books were 50 Facts About Dinosaurs (and how I wish I still owned this – published in 1982, written for children, it is really, really out of date by now) and Monsters of the Deep. Both contained fantastic monsters which, while depicted only by painted illustrations every bit as lurid as those in the Monster Manual, are – or were – real.

All this is brought to mind once again by a news story about dinosaurs – or rather, marine reptiles. Student Raymond Hodgson and groundskeeper Ben Smith found an Icthyosaur fossil in the vegie patch at Richmond State School in western Queensland. The article doesn’t mention how complete a specimen it is, but the icthyosaur is an iconic superstar for anyone who’s familiar with the history of fossil hunting – and if you’re not, I recommend reading up about it. (I have two books on the subject: The Dinosaur Hunters and The Dragon Seekers. Honestly it’s been too long since I read either, and they were both good, but I think it was the latter that I preferred. The former focuses a lot of attention on the rivalry between Gideon Mantell and Richard Owen, though, and that’s quite an exciting back and forth.)

Hardly surprising then that I’ve not blogged much; I’ve hardly had time to catch up to my beloved in Dragon Age: Origins (which is better than Mass Effect, I think). I had to break my busy silence though to celebrate, because it’s been a good month for science!

First, the Large Hadron Collider has been turned on. It’s been a long time coming, and the world hasn’t ended; indeed the press didn’t seem to notice until it was all over. Now, of course, we have to look at the data that the various sensors and arrays and detectors have collected, and see what it tells us about the Universe. It’s going to be an exciting few years…

It’s also been a good month for Simon Singh. In 2008, he mentioned in an opinion piece in The Guardian that he felt certain chiropractic treatments promoted by the British Chiropractic Association (BCA) were “bogus”. For his trouble, he was sued – successfully, in the first instance – by the BCA under the UK’s harsh libel laws. This week? He won an appeal, and what’s more, the appeal court judges were very critical of the BCA’s behaviour – it looked like it was trying to “silence one of its critics” – and of the original judge, who has “marginalised or underrated the value now placed by the law on public debate”. Read more about it in The Telegraph.

In a similar vein, the University of East Anglia scientists whose emails were stolen and publicised as “Climategate”, which supposedly revealed the “truth” behind the “Anthropogenic Global Warming conspiracy”, were cleared by a parliamentary enquiry. The response recognises that they could have been more open in sharing their data, but most of it was already publicly available and the methods for obtaining and analysing it published. They had a culture of “stonewalling” critics at the university, but then when the majority of requests for your data are from people hoping to undermine your research, that might be forgiven… The main point, though, was that plenty of other institutions have come to the same conclusions from data, so even if they had falsified anything, other research still rejects any notion of a conspiracy.

Those are my reasons for a good month. I’ll talk about them some more, with more jokes in, on Friday night. Maybe I’ll see you there?