Lecture 3: The Phone that Shrank the Planet

Ten years ago mobile phones were the size of bricks, as heavy as a bag of sugar and the property of only the very rich. Now they are everywhere, smaller than a credit card and lighter than a Mars bar. But what shrunk the mobile phone, and how come we all have one? Join Tony as he explores the chemistry that connects people and asks what does the electronic chemistry have in store for us?

Professor Tony Ryan
[Tony enters the lecture theatre and runs to answer a jumbo-size 'set' mobile phone.] Hello, welcome to the third [mobile phone rings]... oh. No! Mum! I'm in the lecture theatre! [Laughter]

These things always ring at the wrong times, don't they!
But have you ever stopped to wonder what goes on when you ring your mates upon your mobile phone to talk about what time you'll meet up?

What drives this modern icon?
So, let's find out.

[Tony proceeds to smash phone with hammer.]

[Tony holds up old 'Motorola' phone followed by modern mobile.] You see, your mobile phone has lots of different parts.
So today we're going to look at the bits and pieces that have made it possible to shrink it from this, which is a mobile phone - to this.

So, what's in here? Well, what was in there?
Right. So there's all sorts of bits and pieces.
There's erm, a screen, right.
There's - somewhere, has it gone flying?

[Tony holds up individual components of phone.] Have I lost it? Oh no, here it is.
There's a battery. There were some buttons, right. And the circuit that drives them.

But most importantly there were these things. These here, these are silicon chips.
They've only been around for forty years, but they've caused a technological revolution.
You see before we had these silicon chips, these are the things that powered TVs and radios.
Does anyone know what they are, these things, what they're called? [Tony points at valves.]

You see when I was a kid, oh, we've a hand up here, what are they? [Vacuum tubes]. Vacuum tubes, more commonly known as valves and these valves powered radios and televisions and the difference between those and these is obvious, it's the size.
But they both need the same thing to work - electricity.

[Lightning flash/sound of thunder.]

[Archive photo of Michael Faraday on screen.] You see, electricity's everywhere. It's all around us, it's in our bodies.
Your thoughts are millions of electrical impulses, firing in your brain - and electricity was first understood in the nineteenth century.
People like Michael Faraday who gave the first Royal Institution Christmas Lectures in 1826 was experimenting with the very stuff in this room.

So, what is this magic called electricity?
It's the flow of energy and the energy is in little packets called electrons.

[Demonstration showing effect of 'arcing'.] You're going to see them - jumping - whoa!
And I don't like to get too close to that.
So electrons are jumping between those two balls. This is a really old machine that's been used in many, many Christmas lectures - thank you Bipin.

[Demonstration continues - a bulb is lit by electrons.] And here is another demonstration of electrons. These are in a plasma and they'll even light this bulb.
Can you see it light, as I come close?

The activity of those electrons makes this part of the bulb light up too.
So, what conducts electricity and what doesn't?

I'm going to need some volunteers to help me find out.
Yeah, so I'd like you to come down now, the volunteers.

[Volunteers make their way down.] So, what's your name? [Sukina].
Sukina, please to meet you Sukina, come here.
Now, this won't hurt, right. [Laughter]

[Children demonstrate conduction using various materials.] So there's a contact and there's a contact, right - and if we have conduction, the lights'll go up.
Do you know what this is? [Copper].
Right, let's have a go.
So I just want you to lean, lean it on.

Oh, and how many lights have gone on? All of 'em! [Yeah].
Wow, so that's a good conductor. You see, some materials are good at conducting electricity and some aren't. Why?
Well, if we look on the screen, you can see why. [Overhead screen shows children using balls to demonstrate copper passing on electrons.]
You see, in the copper, there are lots of electrons and they're floating around, so when a new electron comes in, the copper's happy to pass an electron on, because it knows it's going to get to keep one.

So, thank you very much. [Applause]

No, no, no, you two boys get to stay.
Right, what's your name. [Amari].
Amari, right, well let's take the copper off.
This is carbon. Do you want to put that on? You won't get a shock, I promise.
Oh, only two lights have come on. Do you think that's as good a conductor as the copper? [No].
OK, well thank you very much. [Applause]

This is a piece of polythene.
Right, what's your name? [Peter].
Peter, do you want to put it on, Peter and see what happens?
Are you sure it's on?

Yeah, no lights have come on, have they, because this is an insulator, it doesn't like to conduct.
You see, poor conductors, like this polythene, they have no spare electrons and what happens to them is when the electrons come in, they're greedy, they just grab hold of them and they won't let them go.
So that doesn't conduct electricity, so we've seen the difference now between conductors and insulators.

Thank you all very much. [Applause.]

[Tony demonstrates a simple circuit.] So here we have a simple circuit. You see the insulator's useful. It's got copper wire inside.

But it's got an insulator wrapped around the outside, so when I touch this copper wire, I don't get a shock, so you don't want to be touching live wires at all, because they'll give you a shock, so don't do that when you're at home, you have to be careful with electricity.

So in this simple circuit, I've got a source of electrons and when I make the circuit, by making this connection with a switch, the light comes on.
So the light comes on because the electrons are whizzing round this motorway made out of copper.
And then when they get to the light bulb, it's like going from the motorway onto Piccadilly.
They have to slow right down, put their brakes on and give some energy up and when they give their energy up, they give it up in the form of light.

[Tony holds up a mobile phone.] You see, I can use this on/off to send a signal.
My mobile phone is very sophisticated.
This sends signals, but we can use on/off, on/off to send simple signals.

So, let's say I've gone out climbing with my mates and we've got stuck up the mountain.
We don't know where we're going to get to, what's going to happen to us, we're running out of food, it's getting cold.
How can we signal to people that we're lost?
We've no mobile phone.
All we've got is a torch.
What can we do? [Morse code?]

Morse code, brilliant.
[Tony switches light on and off.] So we can go, dot, dot, dot, dash, dash, dash, dot, dot, dot.
And that was the first way of using electricity to send messages.
And now, hopefully, the rest of the lads who are down in the pub will come and rescue us.
So, you see Morse code is the predecessor of binary code.

[Table with 'string' of numbered lights is wheeled in.] So here I've got a string of lights. And each one of them can be on or off.

[Tony demonstrates by switching lights on and off.] And with these eight lights I can encode two hundred and fifty six numbers.
So if I want to encode zero, then I just have a whole string of offs.
If I want to encode one, then I just turn that light on and if I want to encode seventy-two, then I do sixty-four and eight.

Seventy-two in the binary code is zero, one, zero, zero one, zero, zero, zero, right.
And if I want the number four, then I only have this light on. Zero, zero, zero, zero, zero, one, zero, zero.
And if I want to encode two hundred and fifty-five, then, so when all the lights are on it goes one, one, one, one, one, one, one, one and that's the number two five five.

So this method of encoding information is actually very efficient, the binary code.