Steven Pemberton, CWI Amsterdam
Version: 2022-10-01.
At the beginning of my career, my department was discussing what research to do, and asked for ideas.
"Digital music?" I suggested. (We only had 5MB disks then, so they weren't enthusiastic.)
"Digital photography?" (They laughed)
"Programming languages that are easier to use?"
I mentioned Moore's Law, but they all agreed that it would end soon.
The
future doesn't suddenly happen, but comes creeping up, like an oil slick.
If you look at early cars, they really do look like horseless carriages, and nothing like modern cars. They slowly changed, bit by bit, to become what they now are.
So it's interesting to try and identify which bits of current life are the future worming its way in.
For
instance, 31 years ago, the first web server went online.
The Web wasn't a sudden explosion: the internet already existed before the web, and people were already transmitting and receiving files, and communicating over the internet. Similarly, there were also already hypertext systems, just not connected to the internet.
The web just joined the two together, and so wasn't a shock at the time, it just made life somewhat easier.
Before it got fully accepted, we still had to go through several years of people moaning that WWW really stood for "World Wide Wait" because it was so slow, or that it was just a passing fad, or that it was just for geeks.
Image Geni, CC BY-SA 4.0, via Wikimedia Commons
Anyway, I thought I would illustrate the theme of the talk by taking the example of the object that we call the mobile phone.
I say "the object that we call the mobile phone" because frankly, most of the time, most people don't use it as a phone at all. It's a handheld computer, with the ability to make phone calls.
I like to live as much in the future as feasible, and affordable, since it helps deciding what research to do.
For instance, I had an internet-connected watch before there was even mobile internet.
It was a clever device that piggy-backed on FM radio transmissions. You could send messages over the internet, and they would appear on your watch.
Similarly, once there was mobile internet, but before there were 'smart' phones, I had a PDA that would use my non-smart mobile phone as a modem, (connected by IR, no Bluetooth then) so that I could connect to the internet.
Once the first smart phones had emerged, I joked in a talk at a conference, that I had the world's smallest phone, by showing what I used to have to carry, compared with what I carried then.
The joke was meant to be that the phone had merged into the PDA, and so it had become zero-sized, but unfortunately, the joke fell flat, and at the end of the talk, lots of people came up to me to show that they had an even smaller phone than mine...
Anyway, let's do a little bit of time travel, and go back to 1998, the days of the introduction of the mobile phone, and this video of people being asked if they would ever use a mobile phone.
Amazingly enough, a Dutch TV program managed to track down three of those people, including the mother with the baby, who is now a grown man. Of course, they all have mobile phones.
My pre-smart phone PDA had memory measured in megabytes rather than today's gigabytes, but a little Dutch company called Palmtop produced a remarkable maps program.
You bought a CD (this was before DVDs) with a number of maps of world cities, and you could load one, or if they were small enough, two, on your PDA, and then use them for locating addresses, and routes between addresses.
It was quite instructive for me, living in a circular city, where the routes are not always intuitive, even for those who have lived there a long time. This image shows that the shortest route from one end of the Prinsengracht to the other doesn't just follow the Prinsengracht.
One day I got an email from Palmtop, where they expounded their view of the future, where everyone would be able to have a device with the maps of the world on it, and could search for the nearest shop, or whatever, and get a route to it.
And how they were going to rename themselves TomTom.
Those early map systems, and even smart phones, didn't have GPS yet: it was just too demanding of the devices.
GPS works by triangulation. You measure your distance, or angle -- it doesn't matter which -- from something you do know the location of, and then use that to calculate where you are.
For instance, if you know how far you are from a known point then you know you must be somewhere on this circle:
Similarly, if you know your angle from the known point, then you must be on this line:
For each thing you don't know, you need one extra independent measurement. If you need to know your latitude and longitude, you need to have two independent piece of information: for instance, the distance and angle:
Or the angle from two different known points:
Normally when mapping, you need to know three pieces of information: your latitude, longitude and height (GPS works just as well when you're in an airplane, as when you're on the ground.)
With GPS you use your distance from satellites spinning round the earth, and it is actually extraordinary how many things you don't know when using satellites.
(By Paulsava - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=47210072)
First things first: the satellites are constantly sending signals down to earth.
The signals identify the satellite and the time the signal was sent. You receive the signal, work out how long it took to reach you, and based on the speed of light, you can then work out the distance it is from where you are.
Of course, the speed of light is very, very fast, so fast in fact that it is a sign of civilization when people first realise light actually travels.
Although the ancient Greeks wondered if it travelled, it wasn't until the 18th century that we knew conclusively. It is about a million times faster than sound: Mach 1000000!
You already know the speed of sound: during thunderstorms you count the seconds between the flash and the bang and divide by three to give you the distance in kilometers to the strike.
You divide by three because sound travels at about 300 meters per second, and so now you now know that light travels at about 300 million metres per second.
In the case of our GPS satellites, that are 20,000 km high, or 20 million metres, that means it takes about 1/15th of a second for the signals to reach us, so the timers have to be really good.
But there's another problem: the satellites' clocks are mutually synchronised. But your phone's clock isn't.
You know the time that the satellite said it was when it sent the signal, but you don't know the time on the satellite when you received it.
So that means there are 4 things you don't know, the three parts of your position and your time relative to the satellites'.
So you need to be able to see 4 satellites, not 3.
OK, so now
we know the distance between us and the satellites. But there is yet another
thing we don't know: where the satellites actually are.
Contrary to popular belief, they are not at fixed positions in the sky. For that to be possible they would have to be twice as high.
No, the satellites are spinning round the earth about twice a day, travelling at 14000 km/h, or 4km per second.
How do we then work out where they are? Well, they also broadcast an 'almanac', which includes where they were at midnight, and other information.
It's not big, under 2Kbytes, but the satellites broadcast it at the really slow speed of 50 bits per second, and so it takes 12½ minutes to receive.
That is why GPS systems used to start up so slowly.
Nowadays we can also get the almanacs over the internet, speeding up the start time hugely.
From the almanac, we know where they were at midnight, and how fast they are travelling, and in which direction, so now all we have to calculate is how far they have travelled since midnight, and we can work out where they are.
Amazingly, it's even more complicated than that.
If one sign of civilization is realising that light moves, it's an even greater sign of civilization realising that time moves at different rates under different conditions.
Because the satellites are moving at such a high speed, their time moves slower.
But so does ours, though at a different rate, because gravity slows time down as well.
So to calculate where the satellites are, we also have to take both theories of relativity into account.
And finally, there one other thing we don't know: the speed of light.
Although the speed of light in a vacuum is constant, luckily we don't live in a vacuum, and the atmosphere slows light down.
So to work out what the speed of light is today (and it does vary per day), they have a building at a known location that uses exactly the same GPS calculations, but rather than working out where it is, works out what value for the speed of light would give the right answer.
They then beam that number up to the satellites, so that they can add it to the almanac, and beam it down to you.
If we didn't take all these things into account, the accuracy of GPS would be no better than 11km.
As you can see, there is a lot of calculation to be done, and having done it once, your phone then has to do it all over again a second later.
It is no wonder that navigation apps use up so much battery.
With early navigation programs on phones, you had to have a separate dongle that did the reception of the signals, and most of the calculations.
Later, those dongles merged into the phones.
All these improvements are thanks to the process known by the name of Moore's Law: devices are becoming smaller, cheaper, and faster.
Despite what anyone says, it has not ended yet.
(Here is an article by a journalist who had been mourning Moore's Law for a decade, and realised he was wrong.)
Music digitisation happened much earlier than you might have expected, mainly thanks to the invention of the CD.
First released in 1982, with a capacity of 700MBytes, there was surprisingly little vision for a digital future, such as including digital textual details of the content.
The CD was the last of the spinning carriers of music, before music went completely solid state.
Surprisingly, if you analyse the capacity of spinning music media, from wax cylinders, through 78s, LPs and CDs, you can see that the capacity grew exponentially with a doubling time of about 10 years.
After music
went solid-state, mostly thanks to MP3 designed in 1994, there was a brief
period of digital portable music players, whose attraction I never really
understood, since mobile phones were by then just as capable.
Well, 'brief': they took off around 2000, and only this year did Apple announce it was discontinuing the iPod.
The first consumer digital cameras emerged in 1995. The Casio QV10, which cost me dfl 899, had an image size of 320 by 240 pixels.
Here is my very first digital selfie, taken in 1996.
At that time I was editor in chief of ACM interactions, a publication on human computer interaction, and in November 1999 we published a special issue reporting on a project investigating what people would do if digital cameras were integrated into mobile phones.
In this image, you can see the kid holding a digital camera, connected by cable to the electronics in his backpack representing the mobile phone.
Early mobile phones used early LCD screens.
First small, slow, monochrome, and text-only.
Then very basic colour.
The Siemens S10 in 1998 was the first colour phone, with just 4 colours, and only text.
Slowly screens got larger, faster, cheaper, and more colourful.
The Sony-Ericsson T68 was the first colour graphics phone in 2001, 101×80 screen with 256 colours
By 2007 LCDs had become fast enough, large enough, and affordable enough to overtake traditional CRT tubes in televisions.
Funnily enough, we are now seeing almost exactly the same
development in e-ink, the screens used in e-readers since 2004.
E-ink is advantageous because it is more energy efficient and so uses less battery: great for mobile devices.
Ebook readers typically only need to be recharged every week or so. But up to now, e-ink has been monochrome, and slow.
But this year, the first colour ebooks will be released, still a fairly basic colour
but with amazing new developments recently announced.
And a few e-ink displays are now fast enough to display video in a reasonable quality:
Look around and you will see many new things. Voice interfaces, home automation, autonomous devices. All these things are at the beginning of their development. Even the internet is still in very early stages of development.
Once, long ago, a Very Famous Person, who I shan't name and shame, said to me "I will never use an LCD screen: the quality is just not good enough".
And as I said in another talk: Never is a long time.