Off their trolley problem

Why driverless cars don’t care about your ethical dilemmas

If you’ve been paying attention to the media stories about driverless cars, you will have heard the concerns about what driverless cars will do when faced with ethical dilemmas, scenarios in which the car’s computer program has to pick between different options of who to kill when faced with an impending collision. The problem is a variation of the famous, philosophical ‘trolley problem’.

The trolley problem is a thought experiment intended to discuss the ethics of action versus inaction in a no-win situation. The most common variant of the trolley problem goes:

A runaway trolley/train/tram is speeding down railway tracks. Ahead of it, five people are tied to the tracks and are unable to escape. The trolley will kill them. You are standing near a lever in the train yard. If you pull the lever, the trolley will be diverted down a separate track. However, there is also one person tied up and unable to escape on the diverting track. You have two options: do nothing and the trolley kills five people, or pull the lever and the trolley kills only one. What do you do?

There are many interesting variants of the trolley problem, including ones that require you to decide whether you would push a fat man off a bridge in the name of the greater good. (The kind of people who come up with these questions worry me…)

Pretty car

Tesla Model S — semi-autonomous, and, if it takes after the guy it’s named after, may develop an unhealthy attachment to pigeons

Various people have raised concerns that, under certain circumstances, a driverless car could be faced with a similar dilemma. In an impending, fatal crash, does the car swerve to avoid a pedestrian, thus killing the occupant of the car, or does the car stay on course and kill the pedestrian, allowing the occupant to survive? How do we program ethics into the car’s computer?

Like myself, most of the engineers that I posed this question to responded, “That’s a stupid question.”

The trolley problem is a highly contrived scenario that is so abstracted as to have lost all basis in reality. The problem is constructed such that you have no other options. There is no way to stop the trolley, there is no way to warn the people on the track or get them out of the way, the trolley cannot be derailed by pulling the leaver only half way… In real life, and thus, on the road, the trolley problem does not apply.

When this topic of conversation was brought up by some concerned acquaintances, the conversation went something as follows:

Them: What would you do if your car was going to crash and you had to decide between killing a cyclist or a little old lady?
Me: I’d put on the brakes.
Them: What if your brakes have failed?
Me: I’d put on the hand brake.
Them: Both sets of brakes have failed.
Me: Why would I be driving a car with no working brakes?
Them: It’s hypothetical. Let’s say you forgot to get it serviced.
Me: I’d cut the engine and use that to slow down.
Them: You can’t do that.
Me: Why not?
Them: You just can’t.
Me: And I really can’t steer between the granny and the cyclist?
Them: No. You’re between two walls.
Me: I’d steer the car so as to graze along the wall and let friction stop it.
Them: You can’t do that.
Me: Why not?
Them: You just can’t.
Me: Your question is stupid.

I have only been driving for around 10 years, but in that time I have never had to make an ethical decision about who to kill in what situation. No one else I have talked to has ever had to make a similar decision, and, I would be willing to bet, neither have you. If there was any real chance of us having to make ethical decisions about who to kill on the road, it would be part of drivers license exams. (For the love of God, please don’t mention this to the WA government. We don’t need an ethics test to go along with the road-law test, the practical exam, the driving-hours log book, the hazard perception test, the six-month curfew and the two-year probation.)

Like a human driver, the car should be working to avoid any sort of crash, and an autonomous car is likely to be a hell of a lot better at it than a human. With all-round sensors like having eyes in the back of your head, and reaction times that no human could ever hope to match, driverless cars are likely to make our roads far safer than they are now by removing the most failure-prone part of any vehicle, the squishy lump in the driver’s seat.

And how are the engineers working on Google’s self-driving car dealing with the trolley problem and ethical decisions? They are ignoring them, and are designing the car to avoid any crash as best it can. If the situation has developed such that the car has to choose who to run over, the car is so out of control that the question is rendered moot.

Whoever styled the Google cars should not be allowed to style cars.

“Here I am, brain the size of a planet, and they make me drive meatbags to work. Call that job satisfaction, ’cause I don’t.”

Driverless cars will not be infallible, no human-made system is. But they have the potential to make our roads safer, and our journeys far more pleasant. My only worry is that the car’s software will be vulnerable to hackers, and that one day, when deciding whether to hit the cyclist or the little old lady, my car attempts a 7-10 split.

Great Australians — Anthony Michell

We Australians excel at remembering and celebrating our sporting heroes, from cricketers to particularly successful race horses, but are not so good at celebrating the great people who helped build our civilization, particularly when those builders are Australian. Today, I want to celebrate the birthday of a revolutionary Australian engineer, A. G. M. Michell.


Innovator and Inventor

Anthony George Maldon Michell was an Australian engineer who made enormous contributions to a wide range of engineering sciences, from publishing the seminal work on structural optimization, to the invention of the Fluid-film Thrust Bearing. Michell’s inventions operate quietly in the background, but have made a huge impact on our every-day lives.

That's the guy.

Anthony George Maldon Michell (21 June 1870 – 17 February 1959) — engineer

Early life and education

Michell was born in London in 1870 while his parents were visiting from Australia, but grew up and attended primary school in Victoria. He returned to England to attend Grammar school and spent a year studying at Cambridge. He returned to Australia in 1889 to study engineering at the University of Melbourne.

Bearing the load

Of all of Michell’s inventions and innovations, the one that has had the greatest impact is the Michell Bearing, or Fluid-film Thrust Bearing, which he patented in 1905. Michell created a bearing with tilting load-pads that would maintain a thin film of lubricating oil between the metal surfaces. He mathematically derived the pressure distribution in the oil so that the pivot for the tilting pads could be optimally placed to ensure that the pads tilt automatically, under varying load, to the most efficient geometry. At the start of the 20th century, this bearing was revolutionary (pun intended). It could sustain enormous thrust loads with minimal wear and without overheating, while being only one tenth of the size of the bearings it replaced.

Under pressure, do do do didi do do...

Michell thrust bearing — the pads tilt automatically to the most efficient geometry

The low-friction of Michell’s bearings made them much more efficient. Within a decade they had found almost universal application in generators and ships’ thrust blocks. There was some reluctance by the British to adopt Michell Bearings in their ships, until the discovery that the German Navy were using Michell Bearings in their WWI U-Boats, which gave the U-Boats a range and speed that surprised the Royal Navy.

As well as being efficient, the low-wear of Michell Bearings mean they need little maintenance and are very reliable. A Michell Bearing installed at the Holtwood Hydroelectric Power Plant in Pennsylvania in 1912, supporting 165 tonnes of turbine and 40 tonnes of water pressure, is still in operation today. That bearing has been estimated to have a maintenance-free life of over 1000 years.

Michell Bearings, for their strength, efficiency, and reliability are still used on all large ships, power plants and turbines today.

Going with the flow

Another of Michell’s brilliant inventions is the Cross-flow turbine, which has found applications in hydroelectricity generation. This turbine is not used as often as the more common Kaplan, Francis, or Pelton type turbines because it has a lower maximum efficiency. However, cross-flow turbines have a much better efficiency than any of these three when operating at partial load. This gives cross-flow turbines an advantage in small-scale hydroelectric power generation, in situations, such as small rivers, where water flow and pressure can vary widely over the year. Cross-flow turbines are also easier to build, are easier to maintain, and are partially self-cleaning due to the way in which water flows through the blades of the rotor.

Does that count as giving credit?

Cross-flow turbine — image blatantly stolen from Wikipedia

Other innovations

Michell’s other notable innovations include the first published work on structural optimization. Unfortunately, Michell was ahead of his time and this field of research did not gain momentum until computers became a useful research tool some half-century later.

Michell also designed a crankless engine that drew on his work on the thrust bearing and used slipper-blocks on a slanted wobble-plate to convert the reciprocal motion of the pistons into rotary motion of an output shaft. By eliminating the crankshaft, connecting rods, and associated bearings, Michell’s crankless engines could be lighter and more compact than conventional automotive and stationary engines. Proper dynamic design of the wobble-plate also made the engine very low in vibration. Despite successful demonstrations, improved efficiency, and several licensed derivatives, the crankless engine failed to gain wide-spread acceptance and the company formed to produce and market the technology was placed into receivership.

Might be pushing it a bit there...

Michell’s crankless engine — image stolen from somewhere else

Later life

Michell was elected a Fellow of the Royal Society and received several prestigious awards including the Kernot Memorial Medal for distinguished engineering achievement in Australia, and the James Watt International Medal. He continued to make major contributions in engineering research until his death in 1959 at the age of 88.


When asked to list great Australian inventions, most Australians might include the Hills Hoist, Vegemite, the Victa lawnmower, and not much else. Michell, and his bearings that transformed movement and power in the 20th century, deserve to be amongst the first things a proud Australian should include on their list.

Floating in the Sea of Tranquility

Why we should build a swimming pool on the Moon

We choose to build a pool on the Moon, not because it is easy, but because it is hard.

A recent special issue of the New Space journal reported on the reasons and methods for constructing a permanently inhabited lunar colony, and that it could be done within the next few years and for around $10 billion.

On Sundays we go outside and flip off everyone on Earth.

A bargain at only $10 billion.

A lunar colony would provide invaluable experience and technological development for future missions to Mars and beyond, as well as being extremely scientifically useful. The only reason moon colonization missions are not on the cards is because NASA believe they have the budget to get to the Moon, or Mars, but not both. However, as the contributors to the New Space journal have argued, thanks to developments in 3D-printing, life support systems, and reusable launch vehicles, this is no longer the case.

While we’re building that moon colony, we should equip it with an Olympic-sized swimming pool.

That would be really cool

As already demonstrated by Randall Munroe of xkcd What If, a swimming pool on the Moon would be really cool. Due to the low gravity a swimmer wearing fins could leap 4 or 5 metres out of the water. The shear awesomeness of this endeavour would stimulate great interest from the public. A pool would also be a huge morale boost to the crews of the Moon base during their long missions.

Thanks to reusable vehicles such as SpaceX’s Falcon 9 and Dragon, the cost of a flight to an established base on the Moon would fall to a few tens of millions of dollars, putting it in the price range of space tourism trips for eccentric billionaires, and providing a supplementary source of funding.

It would also provide scientists with an opportunity to categorically prove whether or not a human can run on water in low-gravity as predicted by this paper.

Still pretty weird though.

Not even the weirdest thing I’ve seen in the lab.

The technological challenge has massive benefits

Building a swimming pool on the Moon, especially an Olympic-sized one, would be an immense technological challenge, but the technologies developed and lessons learned during this program would kick-start deep space exploration and industries such as asteroid mining.

An Olympic-sized pool of water would be too stupidly expensive to transport to the Moon, even assuming the most optimistic forecasts of SpaceX’s launch cost reductions. The materials to build the pool and the water to fill it would have to be mined from the Moon itself. The tools and techniques developed to mine these resources would have direct application to asteroid mining, an industry that promises to supply huge quantities of rare and valuable minerals without destroying ecosystems back home on Earth. Obtaining resources in this way is a necessary precursor to humanity establishing bases on other worlds.

If they can get those barge landings sorted.

A properly reusable vehicle like the Falcon 9 Heavy will revolutionize space travel.

Mining huge quantities of water from celestial bodies is a necessary step in the production of rocket fuel to support manned missions into deep space. The surest way to reduce the effects and risks of space flight to humans is to reduce the flight time. To do this, we would need refuelling stations at strategic points throughout the solar system. Also, permanent human habitation will require colonists to work to reduce their dependence on supplies from Earth, and this means obtaining huge quantities of water to grow the food necessary to sustain a colony. The Moon would be the first small step of humanity’s giant leap out into the cosmos.

The structure required to house an Olympic swimming pool and protect it from the vacuum of space would be far larger than anything currently envisioned for missions to the Moon or Mars in either the short- or mid-term. However, if humanity is really going to colonize Mars, or other bodies in the solar system, then we are going to need large spaces such as this to play and exercise. If we can’t build large recreation spaces like this one, permanent human habitation of deep-space colonies will not be a realistic goal.

As with humanity’s other forays into space, the technologies developed during the project will have useful, important, and lucrative spin-offs on Earth. For example, waste management and resource recycling systems, of critical importance to a Moon colony, would be applied on Earth to reduce our environmental footprint and improve sustainability.


Building a swimming pool on the Moon will hone the tools and techniques that humanity needs to develop if we are going to expand into deep space and reap the benefits of becoming a truly space-faring race, while the scale of the goal will inspire scientists and the public alike. Big goals spur big leaps in technological and scientific progress, and I think you’d have to agree, this would be pretty cool.

The Wright Stuff

A lesson in innovation from the Wright Brothers

The Australian government’s National Innovation and Science Agenda webpage asserts: “Innovation is at the heart of a strong economy — from IT to healthcare, defence and transport—it keeps us competitive, at the cutting edge, creates jobs and maintains our high standard of living.This recent article from ABC Radio National titled Curiosity, the mother of innovation argues that if we want to stimulate innovation, we need to encourage curiosity. In the article, Peter Macinnis takes his cue from the phrase “necessity is the mother of invention”:

“Necessity, or perceived necessity, won’t do as a starting point for improving the world. What we really need is innovation, and that stems from curiosity, making it the mother of innovation, while serendipity is the midwife and necessity is a mere passing commentator. The message for me as an educator is that if we want innovation to go on into the future, far past my lifetime, we need to ensure that the next generation acquires a strong streak of curiosity.”

The piece is very good and I recommend that you listen to the whole thing, but while I was listening to it, a particularly famous story of innovation and invention came to mind.

As an aviation nerd, I am more familiar with the story of the Wright Brothers than the average person, and I know more of the details of their flying experiments. Popular culture, or at least what I watched and read as kid, often spins the story of the Wright Brothers as a pair of genius inventors who secreted themselves away in their workshop, away from outside influence, applied their brilliance, and emerged with a working flying machine they had invented from scratch. This is patently wrong. I am not disputing that Wilbur and Orville Wright were two of the most influential geniuses of the 20th century, but they were not great inventors, they were brilliant innovators.

The Wright Brothers did not work without external influence and their aeroplane was not composed mostly of their original ideas. Like all great scientists, the Wright Brothers stood on the shoulders of those who came before them, and innovated, adding their own ideas and methods to a science and technology that was already more advanced than the usual stories give credit to.

In the 1890s the goal of powered, heavier-than-air flight was within reach. Sir George Cayley had pinned down the theory of the aeroplane and by 1853 had successfully flown the first manned glider, the cambered aerofoil (aeroplane wing shape) had been developed by both Cayley and Australian engineer Lawrence Hargrave, Samuel Langley had successfully flown some large, steam-powered model aeroplanes, and Octave Chanute had developed an extremely successful biplane hang glider. The Wright Brothers had been keenly following the exploits of the German glider pioneer Otto Lilienthal and believed that a successful aeroplane was only a few years away. They had been interested in flying since their father brought home a rubber-power toy helicopter made of paper, bamboo and cork, which the young Wrights played with until it broke, and then built their own.

I can see my house from up here.

The Wrights were fans of German glider pioneer Otto Lilienthal.

In 1896, Lilienthal was killed when he lost control of his glider. The Wright Brothers were inspired to begin their own work in aviation, and drew on the work of all of these pioneers, an influence that the Brothers always acknowledged. The Brothers based the structure of their gliders and eventual aeroplane on the biplane design of Chanute, they understood the work of Cayley and Hargrave and used published aerofoil research to design their glider’s wings, and they decided to adopt the development process employed by Lilienthal, which was to master gliding flight before moving on to powered machines.

Strap canvas and bamboo to your back and jump of a cliff.

Chanute’s Pratt truss structure bi-plane was the basis of the structure of the Wright Flyer.

The Wright Brothers believed that wings, engines, and airframes were sufficiently advanced and that authoritative control was the final remaining hurdle in developing a successful aeroplane. Lilienthal, Chanute, and other glider pioneers controlled their gliders by shifting their weight. The Wright Brothers believed that this did not provide sufficient authority and developed the 3-axis method of control still used on all aeroplanes today. They built kites and gliders with elevator, rudder, and a wing-warping system that controlled lateral roll. Over successive glider flights the Brothers improved and added to their control system. The 3-axis control is often cited as the Brothers’ greatest contribution to aviation.

High as a kite...

The kite the Wrights used to test their wing-warping control system.

The Wrights’ early gliders produced less lift than they had calculated and so they began testing aerofoils to trace the root of the problem. They attached model wings and metal plates to a balance mounted on a bicycle and pedalled hard to create an airflow over the apparatus, allowing them to measure the lift of the model wing. They later, famously, built a small wind tunnel in which they tested a variety of aerofoils. From this they learned that the cause of the smaller than expected lift of their early gliders was inaccuracies in the published lift information they had been using. The Wrights tested around 200 aerofoils, selecting shapes that improved the lift-to-drag ratio of their wings, and produced a better glider.

Easier than the bicycle.

The wind tunnel the Wrights built to test wing sections.

By 1902 the Wrights were satisfied with their glider experiments and believed they were ready to attempt a powered flight. At this point they encountered more hurdles. The Brothers found that there was very little data on either air or marine propellers and they were unable to find enough information to give them a good starting point in designing a suitable propeller. They returned to their wind tunnel experiments and produced a remarkably efficient propeller. Next, they enlisted the help of their bicycle shop mechanic to build an engine, because they were unable to purchase a sufficiently light-weight unit. They combined all of their experience and innovation in the optimistically named Flyer.

Come and get me Orville!

The Wrights’ 1902 glider was an efficient and controllable flying machine.

The rest, as they say, is history. On 17th December 1903, the Wrights made the first successful aeroplane flight, and age of the aeroplane began.

The Wright Brothers’ efforts and methods provide us with an exciting and influential lesson in innovation. They did not create their Flyer in a technological vacuum, and it was by adding their own ideas and developments to those of others that allowed them to succeed. Articles and photographs of dramatic glides by Lilienthal, as well as a much-used toy helicopter from childhood, piqued the Wrights’ curiosity about aviation, and it was this curiosity that provided them with the drive to research, build, and innovate, and create the world’s first aeroplane. Curiosity will always be the greatest driver of innovation and technological progress, and we should be encouraging it wherever we can.

A flight of 37 metres.

December 17, 1903, the Wright Flyer makes its first flight.

Bring Back Airships

I have a confession to make: I am one of those nut-job engineers who advocates for the return of airships as a means of travel.

Wait! Before you roll your eyes and commit me to an asylum, hear me out.


What prompted me to have a whinge write a post about this is my recent trip to the UK. I have just flown from Australia to the UK for a three day meeting of the Square Kilometre Array Signals and Data Transport consortium. I spent a total of 18 hours in the air, with one stretch of 11 hours cooped up in an aeroplane. I am a very restless person and being confined to a seat for long periods sends me absolutely spare. Comfort is the main factor for me in my support of airships.

The heyday of the airship was the years between world wars one and two. This was the time when the largest aircraft ever built circled the globe, carrying passengers in comfort. The airships of the time had cabins for the passengers, a dining room, a games room, a promenade deck, and even a smoking room. If we were to bring back airships, due to their low speed compared with jet aircraft, passengers would have to be accommodated in similar levels of comfort. You could not ask someone to stay in the same seat for days. There would be room to move around and stretch, and my mental stability would be somewhat preserved.

So, now that my main reason for wanting to ride in an airship is out in the open, let’s consider the other arguments for and against airships.

Giant sky-sausage

A much more comfortable way to fly.


Dining rooms and promenade decks and multi-day flights sound like a recipe for extremely expensive air travel, and indeed, in the 1920s and 1930s airship flights were pretty much the most expensive way to travel. However, I argue that with modern materials and technology the cost of a ticket on an airship could be comparable to an economy seat on a commercial jet-liner.

Since the airship is held aloft by the buoyancy of its gasbags, its engines do not have to be as powerful as a jet-liners. Also, the large surface area of the airship is a convenient place to mount solar panels. Airships could be solar powered and thus have minimal fuel costs.

Admittedly, I have not actually done any calculations to analyse surface area vs power production vs drag, but oh look a distraction!

Helium is expensive and is a non-renewable resource, so I suggest that modern airships use hydrogen. This would be almost free if the airship company uses solar power to produce the hydrogen from water by electrolysis.


“Wait! Hydrogen?!?!” I hear you exclaim.

Despite what the most common depiction of airships would have us believe, using hydrogen to lift the ship is not that unsafe. The loss of the Hindenburg was the Zeppelin company’s first civilian accident. The Zeppelin company was the most experienced operator of airships and had flown tens of thousands of passengers millions of miles in the few decades it had been in existence without incident. The only other times Zeppelins caught fire was during WWI when the Allies deliberately pumped them full of ammunition expressly designed to set Zeppelins on fire. While the Hindenburg disaster was a tragedy, accidents such as that have not stopped us using any other form of transport.

Of the 97 people on board the Hindenburg, only 35 were killed in the accident. That’s a nearly 64% survival rate. Some of those deaths were due to passengers jumping out of the burning airship when it was too high off the ground. The Hindenburg took about 30 seconds to burn, and because it was lighter than air, it crashed slowly. Survivors of the accident made their escape when the Hindenburg settled to the ground.

Even by the standards of the time, the Hindenburg was not a particularly large disaster. Contemporary reports pointed out that commercial aeroplane crashes also occurred and killed similar numbers of people in each crash, and wondered why lighter-than-air aviation had slipped so slow in public opinion. Even today we still accept that there is some risk in flying.

It would be wrong to argue that it would be insane to fill a flying machine with something so inflammable, since we do so every day. Fire is one of the most feared situations in aviation because the planes are loaded with tons of highly inflammable jet fuel. Fires on jet-liners do happen, and when they do, they can take hundreds of lives. A hydrogen fire is less disastrous than a liquid-fuel fire since the buoyancy of hydrogen draws it up and away from people and structures. This is one of the reasons the Hindenburg disaster was relatively survivable. The diesel the Hindenburg carried continued to burn for more than half an hour after the crash.

Today, we also have modern technologies, such as flame-retardant materials and fire-fighting systems, that would significantly reduce the risk and consequences of an airship fire. We could even use a double gas cell design developed by the Hindenburg’s engineers, in which a primary hydrogen gas cell was contained inside a protective helium envelope.

Giant sky sausage on fire.

This didn’t happen very often.


OK, I’ll admit that we have a problem here. But it is not as bad as you think. Airships look slow because they are high up in the sky, but they are actually pretty fast. The Hindenburg and Graf Zeppelin both had top speeds of around 135 km/h. To make the 17,740 km trip from Perth to London at this speed would take… 5.5 days… Ah… Oh dear.

Since a trip from Perth to London currently requires you to spend around one day in transit, I think that a three-day Zeppelin ride would not be unacceptable. This would require the airship to cruise at 200 km/h. This is a considerable increase over the Zeppelins of the 1930s, but might be achievable with modern technology.

Improved engines, greater understanding and modelling of aerodynamics, and low-drag materials would allow a modern airship to fly faster. Modern construction methods and materials would create a lighter airship that could fly higher-up where the drag of the atmosphere is reduced and the airship could move at higher speed. A cruising speed of 200 km/h would be a challenging, but not impossible goal.


Adverse weather would be a significant problem for airships. Because they would fly lower than jet-liners they would not be able to fly above bad weather the way airlines do currently. Modern meteorology, thanks to satellites and radar, would allow airships to navigate around dangerous weather, but this would inevitably cause significant delays.

However, maybe a modern airship would operate at altitudes comparable to a jet-liner and so not suffer from this problem.


While holiday-makers might not mind a three-day cruise, those, like myself, who are travelling for business would object to wasting so much time in transit. But, as long as the airship had good internet access, the time could be spent working and would not be wasted. I would have spent the trip writing and reading papers, preparing presentations, and relaxing in my bunk watching YouTube videos. Airlines already offer some slow and limited internet access, but airships would have to offer large amounts of high-speed broadband. As projects to deliver high-speed internet world-wide, such as Google’s project Loon, Facebook’s, and SpaceX’s internet satellite program, come into operation, convenient internet access on aircraft will become ubiquitous.


A common argument for the return of airships is that they do not need runways, and so can operate in more remote and diverse regions than jet aircraft.

Giant sky-sausage laying an egg.

Airships can operate where aeroplanes cannot.

They look pretty

Come on. You’ve got to admit that airships drifting serenely overhead would be pretty cool to see.


So that’s my argument in favour of airship travel. If you have an idea or information to add for or against this, I would love to hear about it in comments.

Alternatively, we could double the speed of airliners, making the trip much more bearable. But do it quickly. I’ve just checked-in for my flight home.