Vacuum cleaners don’t suck

Anyone that’s known me for more than a few years will know that I am not exactly the biggest fan of cleaning. I like to hoodwink people into thinking I have things sorted and that I exude domestic goddess status but in reality, I honestly don’t care that much. This is slightly problematic for someone with a crazy dust allergy but at the risk of this becoming a personal confessional, let’s move on shall we?

Henry is secretly disgusted in all of us

This deficiency in ability-to-adult is possibly why, when handed a vacuum cleaner as a pivotal prop to use in one of my shows and told to explain how it worked, I laughed hysterically.

But then it occurred to me that it’s highly likely the vast majority of people who frequently use a vacuum cleaner, have no idea how it works either. It’s like any piece of commonplace machinery in modern life; we use it but if asked to pull it apart and put it back together we’d end up with a mess.

Vacuum cleaners, it turns out, don’t suck. In fact a “vacuum” is more than a misnomer – it’s entirely not how they don’t suck and to explain just exactly how they don’t suck, I’m going to need to explain pressure.

First things first we need to think about air pressure. Take a look at your thumbnail. It’s about one square centimeter in area right? Well now I want you to imagine there’s a 1L carton of milk balancing on it. Heavy? Awkward? A contrived gedanken experiment? All answers to these questions should be “yes”. If you ever get a chance, you can actually feel what this is like. All you need to do is get a plastic bag and a vacuum cleaner (stay with me). Wrap the plastic bag around your hand and remove the air from inside it with the vacuum cleaner. You should be able to feel the air outside the bag, pressing onto your skin. Atmospheric pressure is CRAZY.

Vacuum cleaners work on the principle that any areas of high (so higher than atmospheric) and low pressure, if given the opportunity, will want to equalise. This means we can have some fun like this (with added cute-factor) or this (skip to 2 minutes for awesomeness). Now inside a vacuum cleaner, there’s a chamber with a fan. This fan is constantly rotating and works to push the air out of the chamber creating an area of low pressure. This means that the high pressure outside of the vacuum cleaner, instead of getting sucked in, is pushed in so that the high and low pressure equalises.

So vacuum cleaners don’t suck. I’ll definitely be thinking about how I know that the next time I “clean my carpets”*.

*”leave the vacuum cleaner in the cupboard to languish for eternity”.


How to smash a wine glass with your voice

For reasons which will hopefully become clearer as the year goes on, my internet search history has been getting weird. Weirder than usual. Last year, I found myself searching things like “Linear Discriminant Analysis”, “Photosystem II”, “Electron transport chain” and “can you take ibuprofen and paracetamol at the same time?” (you can totally do that without dying by the way but I am by no means a medical professional).

This week, I’ve found myself looking for decidedly more fun things. Including the topic of today’s post: Can you break a wine glass with your voice?


The answer is yes, but there are some caveats.

First of all, you need to be able to sing. Sound is essentially a vibration of the air around the object making the noise. The faster the vibration, the higher the sound and when I say “fast” I mean it. If you think about how fast you can wave your hand back and forth, you’d need to multiply that by about 20000 times to be able to hear your hand…. and you probably wouldn’t have a hand anymore…

Sound waves are what’s called “longitudinal waves”, meaning they move back and forth horizontally rather than, say, waves in the ocean which move up and down. When a thing makes a sound, it’s pushing the air out in really fast compressions. These compressions hit your ear and, through a complex process involving teeny tiny bones and millions of neurons, your brain converts them to sound. This is part of the theory behind the glass smashing. Point your horrifically powerful voice towards a glass and it starts to get bombarded by compressed air. The higher the sound, the faster the vibration which increases the amount of air hitting the glass and boom! It should explode.

But there’s actually one other thing happening; resonant frequency. If an object is hit with just the exact right pitch of sound, it will start to vibrate. Crystal glasses are really really good at resonating depending on the pitch of the sound. The more the glass vibrates, the more the molecules making it up are disrupted. If you hit a glass with a mallet, it makes a ringing noise. Match the frequency of the ring with your voice and you’ve got a very good chance of breaking it. Especially if it’s got a few cracks in it already.

So essentially, you need to be good, you need to be loud and you need to be very, very lucky. Like this guy on Mythbusters that one time. Awesome right?

Gedanken experiments: the art of avoiding fork-in-hand situations

I want you all to do something for me. Don’t worry, this won’t be horrifyingly embarrassing; you can do this sitting down and in the comfort of your own home. I want you to imagine placing your hand onto the table in front of you and pressing down. The force needs to be equal and constant.

Ok you can stop now. (Take your hand away from the table – you’re supposed to be thinking, not doing).

I want you to imagine that you’re pressing down with the same hand and the same amount of force. This time, instead of the table, you’re pushing your hand onto a fork (bet you’re glad you’re imagining now right?). Which one are you reluctant to do? Which one hurts more? If you answered “the fork!” then you’re absolutely right and your sense of self-preservation is clearly working.

What I just asked you to do is what’s called a “Gedanken” experiment. It’s a common device used in science communications to illustrate an idea without, say, the fuss and bother of calling an ambulance to deal with any awkward fork-in-hand situations.

The term was coined by none other than Albert Einstein. In his first language, German, it means “thought experiment”. Einstein famously used this method to develop and communicate his theory of general relativity. His memoirs are riddled with stories from his imagination that led him, step-by-step, to his ground-breaking conclusions. Like this one:

I was sitting on a chair in my patent office in Bern. Suddenly a thought struck me: If a man falls freely, he would not feel his weight. I was taken aback. This simple thought experiment made a deep impression on me. This led me to the theory of gravity.

Einstein concluded, through further thought and relation to everyday situations like riding in a lift, that within a given system, it is impossible to tell the difference between effects relating to gravity and extra acceleration. General relativity. You may also have heard the story of a night spent imagining himself riding a light beam… It’s a little hard to do in real life so Einstein had to be creative and then come back and prove his thought excursions were legitimate in other ways.

So why the weird and slightly worrying fork experiment?

Well sometimes it’s hard to demonstrate a principle to an audience without involving ridiculously convoluted or horrifically dangerous demonstrations. The use of the table vs fork experiment to illustrate that pressure decreases with increasing surface area, gives an audience something to relate to. I’m sure you winced at the thought of pressing your hand onto something sharp? Yes?

Then I declare the thought experiment a success.

The Great Barrier Reef (may contain traces of giant sea turtles)

So it looks like the video blogging is becoming a bit of thing. This is part 1 of a series of videos outlining what’s going on in reef systems around the world. I’m hoping to channel the knowledge I’ve been gathering over the last three years and present it to you. Mainly because I think it’s super interesting, but also because I think it helps to understand why the reefs are dying, and why that’s such a terrible thing.

This was, again, really fun to do so I hope you enjoy it. Please feel free to share it around and follow me on my new youtube channel; The Confusion Matrix.


(Oh and don’t worry – I’ll still be posting things up on this site – not everything translates so well to video medium…)

The mighty, marvellous, magnanimous, miraculous miracle berry

If you’re a fan of the British TV show, QI, you’ve probably heard of the Miracle Berry. Synsepalum dulcificicum has been used in Western Africa for generations, to make harsh, acidic foods taste like they’ve been dipped in sugar. A few days ago, I got to try some and let me tell you, there is nothing more brain-twisty than lifting a slice of lemon to your mouth fully expecting your face to be turned inside out, but then all you taste is sherbet.

It’s weird. Here’s how it works.

Also please forgive the video quality – the more I venture into this area of media communications, the more I learn about how to frame a shot (… or not, as you’ll see), lighting, flow and a whole pile of other things I want to make better the next time I make a video. I had a blast creating this though so I call that a win. Hope you enjoyed it as much as I did!