After yesterday’s tinsel image inspiring a cable / broadband speeds themed post, today’s CS4FN Christmas Computing Advent Calendar picture of a candle has of course put me in mind of optical fibre, then that eminded me of optical illusions, so this is a light-hearted (sorry) look at those, shining a torch (or candle) into the CS4FN archives.
We’re now more than halfway through our advent calendar, having posted something every day for the last 15 days. Do we have enough material for the next 10 days? You betcha 🙂 CS4FN has been running for 16 years and we’ve produced 27 magazines for subscribing UK schools (they’re free, get your teacher to subscribe for next year’s magazine) and a whole load of other booklets and posters etc. We’ve been busy!
Read about the change in speeds in communications, from letters via pony express, to Morse via telegraph wires, then telephones via copper wires, and modern digital computing – and now at the speed of light via optical fibre.
Optical illusions tell us about how our brains work. They show that our brains follow rules that we cannot switch off.
Stare at the picture, moving your head a little as you do. The middle circle floats around as though it is not part of the rest of the eye. It isn’t moving of course. It was created by the Japanese artist Hajime Ouchi.
Your brain is doing some amazing tricks – turning the light hitting your eye into an understanding of the world around you. Knowing what is near and what is far, and whether there is movement, are things that all animals must do quickly (especially when a tiger is near rather than far!)
To work things out your brain makes some guesses. It has built in rules that spot patterns. One rule helps us guess if something is moving up and down. Another spots side to side movement.
The patterns in this picture trigger those rules, telling you there are two separate objects. The rules that allow your brain to make sense of the world quickly are telling you the wrong thing, and you cannot stop it happening!
Programs that allow computers to “see” like we do have to do more than record things like a camera. They need to make sense of what is there. They need to be able to tell objects apart. A driverless car needs to tell if that blotch of darkness is a pedestrian or just a shadow.
Machine learning is one way to do this. The computer learns rules about patterns in the data it records just as we do. If they do it well robots of the future may be fooled by the same optical illusions that we are.
Answer to yesterday’s puzzle
The creation of this post was funded by UKRI, through grant EP/K040251/2 held by Professor Ursula Martin, and forms part of a broader project on the development and impact of computing.
Only two letters were transmitted over the Internet before it crashed for the first time. The Internet was born on 20 October 1969 with the first transmission of data sent from a computer at the University of California to another one at Stanford, near San Francisco. Only two letters L and O were sent – the system crashed when the G of LOGIN was entered.
The Internet is now so much a part of life that, unless you are over 50, it’s hard to remember what the world was like without it. Sometimes we enjoy really fast Internet access, and yet at other times it’s frustratingly slow! So the question is why, and what does this have to do with posting a letter, or cars on a motorway?
The communication technology that powers the Internet is built of electronics. The building blocks are called routers, and these convert the light-streams of information that pass down the fibre-optic cables into streams of electrons, so that electronics can be used to switch and re-route the information inside the routers.
Enormously high capacities are achievable, which is necessary because the performance of your Internet connection is really important, especially if you enjoy online gaming or do a lot of video streaming. Anyone who plays online games would be familiar with the problem: opponents apparently popping out of nowhere, or stuttery character movement.
So the question is – why is communicating over a modern network like the Internet so prone to odd lapses of performance when traditional land-line telephone services were (and still are) so reliable? The answer is that traditional telephone networks send data as a constant stream of information, while over the Internet, data is transmitted as “packets”. Each packet is a large group of data bits stuck inside a sort of package, with a header attached giving the address of where the data is going. This is why it is like posting a letter: a packet is like a parcel of data sent via an electronic “postal service”.
But this still doesn’t really answer the question of why Internet performance can be so prone to slow down, sometimes seeming almost to stop completely. To see this we can use another analogy: the flow of packet data is also like the flow of cars on a motorway. When there is no congestion the cars flow freely and all reach their destination with little delay, so that good, consistent performance is enjoyed by the car’s users. But when there is overload and there are too many cars for the road’s capacity, then congestion results. Cars keep slowing down then speeding up, and journey times become horribly delayed and unpredictable. This is like having too many packets for the capacity in the network: congestion builds up, and bad delays – poor performance – are the result.
Typically, Internet performance is assessed using broadband speed tests, where lots of test data is sent out and received by the computer being tested and the average speed of sending data and of receiving it is measured. Unfortunately, speed tests don’t help anyone – not even an expert – understand what people will experience when using real applications like an online game. Electronic engineering researchers at Queen Mary, University of London have been studying these congestion effects in networks for a long time, mainly by using probability theory, which was originally developed in attempts to analyse games of chance and gambling. In the past ten years, they have been evaluating the impact of congestion on actual applications (like web browsing, gaming and Skype) and expressing this in terms of real human experience (rather than speed, or other technical metrics). This research has been so successful that one of the Professors at Queen Mary, Jonathan Pitts, co-founded a spinout company called Actual Experience Ltd so the research could make a real difference to industry and so ultimately to everyday users.
For businesses that rely heavily on IT, the human experience of corporate applications directly affects how efficiently staff can work. In the consumer Internet, human experience directly affects brand perception and customer loyalty. Actual Experience’s technology enables companies to manage their networks and servers from the perspective of human experience – it helps them fix the problems that their staff and customers notice, and invest their limited resources to get the greatest economic benefit.
So Internet gaming, posting letters, probability theory and cars stuck on motorways are all connected. But to make the connection you first need to study electronic engineering.
The 11 words to fill in the squares in the puzzle above are: Advent, Bauble, Cards, Chimney, Decorations, Presents, Reindeer, Sleigh, Snowman, Stocking, Tree. Answer tomorrow.
From an earlier puzzle “You might wonder “What do these kriss-kross puzzles have to do with computing?” Well, you need to use a bit of logical thinking to fill one in and come up with a strategy. If there’s only one word of a particular length then it has to go in that space and can’t fit anywhere else. You’re then using pattern matching to decide which other words can fit in the spaces around it and which match the letters where they overlap. Younger children might just enjoy counting the letters and writing them out, or practising phonics or spelling.”