Big companies know far more about you than you think. You have very little privacy from their all-seeing algorithms. They may even have worked out some very, very personal things about you, that even your parents don’t know…
An outraged father in Minneapolis stormed into a supermarket chain complaining that his school-aged daughter was being sent coupons for baby clothes. The shop manager apologised … but later they found there was no mistake in the tiny tot offers. The teenager was expecting a baby but had not told her father. Her situation was revealed not by a crystal ball but by an algorithm. The shop was using Big Data processing algorithms that noticed patterns in her shopping that they had linked to “pregnant”. They had even worked out her likely delivery date. Her buying habits had triggered targeted marketing.
Algorithms linked her shopping patterns to “pregnant”
When we use a loyalty card or an online account our sales activity is recorded. This data is added to a big database, with our details, the time, date, location and products bought (or browsed). It is then analysed. Patterns in behaviour can be tracked, our habits, likes, dislikes and even changes in our personal situation deduced, based on those patterns. Sometimes this seems quite useful, other times a bit annoying, it can surprise us, and it can be wrong.
This kind of computing is not just used to sell products, it is also used to detect fraud and to predict where the next outbreak of flu will happen. Our banking behaviour is tracked to flag suspicious transactions and help stop theft and money laundering. When we search for ‘high temperature’ our activity might be added to the data used to predict flu trends. However, the models are not always right as there can be a lot of ‘noise’ in the data. Maybe we bought baby clothes as a present for our aunt, and were googling temperatures because we wanted to go somewhere hot for our holiday.
Whether the predictions are spot on or not is perhaps not the most important thing. Maybe we should be considering whether we want our data saved, mined and used in these ways. A predictive pregnancy algorithm seems like an invasion of privacy, even like spying, especially if we don’t know about it. Predictive analytics is big; big data is really big and big business wants our data to make big profits. Think before you click!
Jane Waite, Queen Mary University of London (now at Raspberry Pi)
Researchers in Japan made a robot arm that always wins at rock, paper, scissors (a game completely of chance). Not with ultra-clever psychology, which is the way that the best humans play, but with old-fashioned cheating. The robot uses high-speed motors and precise computer vision systems to recognise whether its human opponent is making the sign for rock, paper or scissors. One millisecond later, it can play the sign that beats whatever the human chooses. Because the whole process is so quick, it looks to humans like the robot is playing at the same time. See for yourself by following the link below to watch the video of this amazing cheating robot.
The word ‘robot’ came to the English language over 100 years ago in the early 1920s. Before that the words ‘automaton’ or ‘android’ were used. In 1920 Czech playwright Karel Čapek published his play “R.U.R.” (Rossum’s Universal Robots, or Rossumovi Univerzální Roboti) and his brother Josef suggested using ‘roboti’, from the Slavic / Czech word meaning ‘forced labour’. In the late 1930s there was a performance of the play at the People’s Palace in London’s Stepney Green / Mile End – this building is now part of Queen Mary University of London (some of our computer science lectures take place there) and, one hundred years on, QMUL also has a Centre for Advanced Robotics.
You might think that under the sea things are nice and quiet, but something fishy is going on down there. Our oceans are filled with natural noise. This is called ambient noise and comes from lots of different sources: from the sound of winds blowing waves on the surface, rain, distant ships and even underwater volcanoes. For undersea marine life that relies on sonar or other acoustic ways to communicate and navigate all the extra ocean noise pollution that human activities, such as undersea mining and powerful ships sonars, have caused, is an increasing problem. But it’s not only the marine life that is affected by the levels of sea sounds, submarines also need to know something about all that ambient noise.
In the early 1900s the aptly named ‘Submarine signal company’ made their living by installing undersea bells near lighthouses. The sound of these bells were a warning to mariners about the impending navigation hazards: an auditory version of the lighthouse light.
The Second World War led to scientists taking undersea ambient noise more seriously as they developed deadly acoustic mines. These are explosive mines triggered by the sound of a passing ship. To make the acoustic trigger work reliably the scientists needed to measure ambient sound, or the mines would explode while simply floating in the water. Measurements of sound frequencies were taken in harbours and coastal waters, and from these a mathematical formula was computed that gave them the ‘Knudsen curves’. Named after the scientist who led the research these curves showed how undersea sound frequencies varies with surface wind speed and wave height. They allowed the acoustic triggers to be set to make the mines most effective.
Whenever humans have complicated, repetitive jobs to do, designers set to work making computer systems that do those jobs automatically. Autopilot systems in airplanes are a good example. Flying a commercial airliner is incredibly complex, so a computer system helps the pilots by doing a lot of the boring, repetitive stuff automatically. But in any automated system, there has to be a balance between human and computer so that the human still has ultimate control. It’s a strange characteristic of human-computer interaction: the better an automated program, the more its users rely on it, and the more dangerous it can be.
The problem is that the unpredictable always happens. Automated systems run into situations the designers haven’t anticipated, and humans are still much better at dealing with the unexpected. If humans can’t take back control from the system, accidents can happen. For example, some airplanes used to have autopilots that took control of a landing until the wheels touched the ground. But then, one rainy night, a runway in Warsaw was so wet that the plane began skidding along the runway when it touched down. The skid was so severe that the sensors never registered the touchdown of the plane, and so the pilots couldn’t control the brakes. The airplane only stopped when it had overshot the runway. The designers had relied so much on the automation that the humans couldn’t fix the problem.
Many designers now think it’s better to give some control back to the operators of any automated system. Instead of doing everything, the computer helps the user by giving them feedback. For example, if a smart car detects that it’s too close to the car ahead of it, the accelerator becomes more difficult to press. The human brain is still much better than any computer system at coming up with solutions to unexpected situations. Computers are much better off letting our brains do the tricky thinking.
Pots are buried in the walls of medieval churches and monasteries across Europe: in the UK, Sweden, Denmark and Serbia. Why? Are they just a weird form of decoration? Actually, they are there to fix problematic acoustics.
The problem
First of all, what do we mean by ‘problematic’ acoustics? When sound waves move around a room they reflect off the walls in a way that creates strange sound effects when they meet their reflections.
It happens because of what are called ‘standing waves’. Imagine dropping a pebble into a bath. The ripples create patterns in the water where they interfere with those that have bounced off the sides. As the two ripples pass in opposite directions if the movement pushing the molecule up from one ripple exactly cancels out the movement pushing down from the other and keeps doing so, then at that point the molecules remain still. On either side the two ripples reinforce each other rather than cancelling out giving the peaks and troughs of the combined wave. The result is the ripples appear to stop moving forward: a standing wave.
Sound waves are like water waves except that the air molecules vibrate from side to side rather than up and down as water molecules do. The same effects therefore happen when sound waves meet and standing waves can form. This is bad for two reasons. Standing waves take more time to die away after the sound source has been silenced than other sounds. Worse, the sound’s volume varies around the room depending on whether it is a point where the waves cancel out (no sound) or where they enhance each other (loud). That’s ‘problematic’ acoustics!
Standing Wave.By Lucas Vieira – Own work, Public Domain, from WIKIMEDIA
These acoustic problems ultimately come about because of what is known as ‘resonance’. That is where a sound repeatedly bounces back and forth across a space at a particular frequency. Frequencies that are directly tied to the room’s dimensions cause most problems. Called the ‘resonant frequencies’ they involve a whole number of wave troughs and crests fitting in the space between the walls. That is what leads to standing waves as the original and reflected wave coincide exactly. The lowest resonant frequency of a wave is also called the ‘fundamental frequency’. It’s the one where a single wave (a single trough and crest) fits in the space.
There are three different types of resonances developed in a room from sounds bouncing of the walls: called axial, tangential and oblique modes. Axial modes result from a sound bouncing back and forth between two facing walls. Tangential ones happen when the waves reflect around all four walls. Oblique modes are the most complicated and result from sound bouncing off the roof and floor too. Of all these, it turns out the worst are the axial modes. To improve the acoustics of a room you need to absorb the sounds at these resonant frequencies. But how?
The solution
OK, now we know the problem, but how do we deal with it? A solution is the ‘Helmholtz resonator’, named after a device created by Hermann von Helmholtz in the 1850s as part of his studies to identify the ‘tones’ of sounds. A Helmholtz resonator is just the phenomenon of air resonating in a cavity. It is the way you get a tone from blowing across the mouth of an empty bottle. The frequency of the tone is the resonant frequency of the bottle. If you change the volume of the air cavity or the length or diameter of the neck of the bottle you change its resonant frequency and so the tone.
A Helmholtz resonator actually absorbs sound at its resonant frequency and at a small range of nearby frequencies. This happens because when a sound strikes the resonator’s opening, the air mass in the neck starts to vibrate strongly at that resonant frequency and tries to leave. That makes the pressure of the air in the cavity lower than the outside. As a result it draws the air back into the cavity. This process repeats but energy is lost each time, which causes the wave, of this particular resonant frequency, to dissipate. That means that specific sound is absorbed by the resonator. Helmholtz resonators also reradiate the sound that is not absorbed in all directions from the opening. That means any energy that wasn’t absorbed is spread around the room and that improves the room’s acoustics too.
So back to those pots in the walls of medieval churches. What are they for? Well they would have acted as Helmholtz resonators so they presumably were designed to remove low-frequency sounds and so correct the acoustic of the vaults and domes. Ashes have been found in some of the pots. That would have increased the range of sound frequencies absorbed as well as helped spread the unabsorbed sound. St Andrew’s Church in Lyddington, Rutland, built in the 14th Century, has some of the finest examples of this kind of acoustic jars in the UK. Helmholtz resonators obviously predate Helmholtz, actually going back to the ancient Greeks and Romans. The pots in churches are thought to be based on the ideas of Roman architect Vitruvius. He discussed the use of resonant jars in the design of amphitheatres to improve the clarity of the speakers’ voices.
Designers of acoustic spaces like concert halls now use a variety of techniques to fix acoustic problems including Helmholtz resonators, resonant panels and tube traps. They’re all efficient ways for absorbing low-frequency sounds. Helmholtz resonators though have the particular advantage of being able to treat localized ‘problematic’ frequencies.
Those church designers were apparently rather sophisticated acoustic engineers. They had to be, of course. It would have been a little unfortunate to build a church so everyone could hear the word of God, only to have those words resonate with the walls rather than with the congregation.
– Dimitrios Giannoulis, Queen Mary University of London
Bank holiday bunting appears automatically on the GOV.UK website thanks to a little program! If you’re reading this post today (Monday 21 April 2025) it’s Easter Monday which is a Bank Holiday in England & Wales and in Northern Ireland you have a chance to see it.
The UK Government’s website has a UK Bank Holidays page which lists all the upcoming dates for the next two years’ worth of bank holidays (so people can put them in the diaries) for England & Wales, Northern Ireland and Scotland (the different UK nations share many but not all bank holidays).
But… if you visit the page on a Bank Holiday then you may be met with some bunting, which doesn’t appear if you visit the page on a non-bank holiday day. People who look after the website added in this little Easter egg* over a decade ago and people have been discovering it ever since. They use an Application Program Interface (API) which connects the bank holiday website to a database which lets the website check, whenever there’s a bank holiday, whether it should display bunting. For example Easter Monday is a celebratory day in the Christian calendar but Good Friday isn’t. Both are holidays but it wouldn’t be appropriate for bunting on Good Friday so it gets the instruction “bunting: false” whereas Easter Monday is “bunting: true”. You can see the API’s instructions here.
If you’re reading this post after Easter Monday 2025 you still have more chances to catch the bunting on the Early May bank holiday, the Spring bank holiday, though then you’ll need to wait until August for the Summer bank holiday then a few more weeks before Christmas Day, Boxing Day and New Year’s Day and New Year’s Day – on those days the bunting changes to tinsel!
*it’s not called an Easter egg because it’s there at Easter, the bunting is there at other times too but because it’s something to discover (like Easter Egg Hunts – find ours at The CS4FN Easter Egg Hunt).
– Jo Brodie, Queen Mary University of London
This is an updated version of a snippet that appeared previously on this blog.
Part of a series of ‘whimsical fun in computing’ to celebrate April Fool’s (all month long!).
Subscribe to be notified whenever we publish a new post to the CS4FN blog.
This blog is funded by EPSRC on research agreement EP/W033615/1.
Mark Rober, an engineer and YouTuber who worked for NASA, has created a dartboard that jumps in front of your dart to land you the best score. Throw a dart at his board and infra-red motion capture cameras track its path, and, software (and some maths) predicts where it will land. Motors then move the dartboard into a better position to up the score in real time!
To track the dart Mark used a motion-capture system with six cameras that respond to infrared instead of light (this let the cameras follow the movement of just the dart, which had a special infrared reflecting surface, and not all the other stuff in the room that would distract a light-sensing camera). He used Matlab to program the maths needed to calculate (very quickly!), from the parabolic path the dart was flying in, where it was about to land, so that the dart board could be moved into place and meet it. The movement of the darts board was controlled by fishing wire (literally) and small motors to pull the board left, right, up or down under the control of an Arduino.
Possibly the most ridiculously over-engineered thing but a lot of fun, even if a bullseye isn’t the highest possible score on a dart board (hitting the bullseye gives you 50 points but landing your dart in the triple 20 segment gives you 60!)
An earlier version of this post originally appeared both on this blog and on the back page of issue 28 of the CS4FN magazine, Cunning Computational Contraptions, a fun look at the history of computational devices which you can download as a PDF from the link below.
This issue of the magazine contains articles about automata, core rope memory (used by NASA in the Moon landings), Charles Babbage’s Analytical Engine (never built) and Difference Engine made of cog wheels and levers, mercury delay lines, standardising the size of machine parts, Mary Coombs and the Lyons tea shop computer, computers made of marbles, i-Ching and binary, Ada Lovelace and music, a computer made of custard, a way of sorting wood samples with index cards and how to work out your own programming origin story….
Part of a series of ‘whimsical fun in computing’ to celebrate April Fool’s (all month long!).
Subscribe to be notified whenever we publish a new post to the CS4FN blog.
This blog is funded by EPSRC on research agreement EP/W033615/1.
Do you know how to make a sandwich? More importantly do you know how to write down a set of precise, detailed instructions that could tell someone else how to make a sandwich? I’m sure you think you could, but after watching this video below you might feel less sure.
This video has been used in some classrooms as a fun way of talking about how precise and correct an algorithm needs to be in order to run a program correctly. Josh, the dad in the video, asks his children (Johnna and Evan) to write out some instructions to make a peanut butter and jelly (jam) sandwich. They all speak the same language (English) so the instructions don’t have to be converted into machine language for the computer (dad) to run the program and make the sandwich, but as you’ll soon see, it’s harder than his children think. They do get there in the end though… kind of.
See if you can write your own set of instructions and then get someone to follow them exactly.
Incidentally, the image used to illustrate this article has been “…assessed under the valued image criteria and is considered the most valued image on Commons within the scope: peanut butter and jelly sandwiches. You can see its nomination here.” Only the best peanut pics on this site! You can see all the images that didn’t win here.
Kew Gardens‘ 404 error page (click here to see it) says “Oops! 404 error. We’ve been doing a bit of website weeding. The content on this page has been uprooted and planted elsewhere. Please keep digging.” The page helpfully links to other pages on their site. Flowers Image by 👀 Mabel Amber, who will one day from Pixabay with writing added by CS4FN.
Have you ever seen a website say “404 – page not found” or something very similar? This can happen if a page has since been moved or deleted, or if you’ve typed the address wrongly so the page can’t be loaded. Most of the time the error messages are fairly dull – some of them might even be slightly useful and point you to the homepage or let you search the website to try and find the page you were looking for.
Sometimes organisations make a bit of an effort and produce an error message that is also entertaining, though, adding delight to the user experience design. For example Kew Gardens keeps the ‘garden’ theme going in its message, and Innocent Drinks has a whole page describing previous errors that the company has made. Lego‘s 404 not found page has a picture of a minifigure dressed as a construction worker who’s looking a bit worried and the page says “We’ll try not to lose our head over this, but if we do… we’ll put it back on.”
‘404’ has become the universal language of ‘something that is not found or cannot be found’. If you are ever in a computer science department that happens to have a Room 404 there’s a very high chance that someone will have jokingly added a post-it note saying “Room not found”.
Incidentally if you were to search on Google Maps for CS4FN’s building (the Peter Landin teaching rooms, originally called the Bancroft Road Teaching Rooms) you’d find that someone has changed our address to 404 Bancroft Road (click the link to see if it hasn’t been changed back since). We’re not sure who did it or why but we’re fairly sure a computer scientist in the department was behind it.
Why “404”?
There may be different reasons that a website can’t load a page and sometimes it can be helpful to know why. You might be reassured to know that the problem isn’t anything to do with you, and to be told that the server that is hosting the pages is busy or down for maintenance and you should come back later. Rather helpfully there is a list of agreed “server response codes” so that whenever a page won’t load a differently numbered message appears depending on the reason.
There are quite a lot of these messages and they all have three digits. If the digit starts with the number 4 then it means that the problem may have come from the user (such as you typing in a web address wrongly so being given the 404 message). If it starts with the number 5 it means a problem on the server’s side and it’s not probably going to be able to show you pages because of a fault. You might also have seen “Error 503 – Service unavailable” – that’s usually a temporary fault just try again later.
Making 404 pages more useful
In 2012 a group of organisations that helps raise awareness about missing children encouraged companies to add some helpful information to their 404 pages so that every time someone landed on their ‘wrong’ page they’d be shown a name and photograph and any relevant information about someone the police and emergency services were trying to locate, and who to call if they knew who they were. What a great idea!
– Jo Brodie, Queen Mary University of London
Part of a series of ‘whimsical fun in computing’ to celebrate April Fool’s (all month long!).
Subscribe to be notified whenever we publish a new post to the CS4FN blog.
This blog is funded by EPSRC on research agreement EP/W033615/1.
Wheel Barometer, also known as Banjo Barometer, Barnasconi, Leeds, c. 1810 – Museum of Science and Industry (Chicago), via Wikimedia Commons under a CC0 licence.
There’s an old science joke about a physics professor who gives, as weekend homework, the task to use a barometer* to measure the height of the physics building. Back in class on Monday the professor invites the students to share their working. The class discuss how they measured the pressure at the base of the building, climbed to the top and measured it again then used a mathematical formula to work out the height. One of the students admitted that he’d saved a bit of time, measurements and calculations by simply knocking on the door of the janitor’s office and saying “If you will tell me the height of this building, I will give you this beautiful barometer.“
Social engineering
One of the simplest and often quickest ways to ‘hack’ into someone’s account doesn’t involve any hacking (or cracking) at all. People lose lots of money, time and anxious sleep to mistakes made because they were distracted and fell for something which was cleverly designed to fool them. Most cyberattacks happen not because someone guessed a password but because someone willingly handed it over.
Phishing attempts can involve little more than making a fake website look like a real one and hoping people don’t notice that the address doesn’t look right. Someone clicks on the link, perhaps in an email or a text message telling them that there’s something wrong with their account that they need to deal with urgently, and enters their email address and password – handing their account details to the scammer. Worse, when people re-use an email address with the same password on multiple sites the scammers suddenly have access to a great deal more of their private information and perhaps even access to their money (e.g. if they have stored payment details with their account).
Back in the 1980s ‘Claire’ managed to hack into a computer network with incredible ease as her son explained in a series of posts. Claire, known as someone who was ‘good with computers’, was invited to a meeting by the CEO of a company that made security systems. She visited his office, taking the lift all the way up to the penthouse office, where he offered her “an eye-watering sum” if she was able to break into his system within a week.
Offer accepted she took the lift all the way down to the building’s basement where the computer lab was. She found a stack of papers and stood outside the lab door looking busy and needing to get on with her work but struggling to get in with all the papers. One of the lab technicians helps her into the room (how kind! she’s ever so grateful!) where she makes her way to an unused computer, sits down and calls out “What’s today’s password?”. And someone tells her. It took her less than 20 minutes!
It is easy to be tricked
I (PC) was at a workshop about security. As part of it we were shown a website that could tell you how safe your password was. It gave an estimate of how long any password could be cracked in. If you typed in 1234 then it would tell you that was cracked in fractions of seconds. A word in any dictionary (even a Tolkien one) likewise. Longer passwords would take longer than shorter ones. Mix in capitals and it would take longer still, and so on. Everyone was told to type in their passwords to find out how good they were at thinking up a password. Virtually everyone did so and many found out that their passwords were not very good… others celebrated the fact that they were good at choosing a password. However, perhaps it didn’t matter either way! Everyone who typed in an actual password had just given away their password to a website that may or may not have been secure…
Never give up your password to anyone and certainly not to a computer program. Don’t even tell others the rules you use to create one!
How do you decide a website is safe? You do not judge it by looking at the website itself. You look elsewhere to a trusted source and find information that way! Either way do not ever enter personal data and passwords into a source unless you are absolutely sure.
You can also try Take Five‘s quiz to see how ‘Scamsceptible’ (susceptible to scams) you are based on how well you slept last night and if you have lots of things on your mind distracting you. Take Five is a campaign to encourage people to pause (and take five minutes) when they get a message they’re not sure about and double-check that it’s genuine.
– Jo Brodie and Paul Curzon, Queen Mary University of London
Part of a series of ‘whimsical fun in computing’ to celebrate April Fool’s (all month long!).
Subscribe to be notified whenever we publish a new post to the CS4FN blog.
This blog is funded by EPSRC on research agreement EP/W033615/1.
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