My Favourite Units

Posted on September 26, 2017 by drgozz

Since the dawn of civilization, we have needed ways to define and quantify the world around us, to conduct trade, build homes, and explore further. To do this, we need to agree on the way we measure the world, we need to agree on the units. While we no longer use the size of the king’s nose or the number of doughnuts a pregnant duck can eat to quantify things, and instead rely on carefully defined standards sweated over by the world’s best metrologists (measurement scientists), people have invented some wild and wacky ways of figuring out how much of something there is. Here are some of my favourite weird units of measurement.

Helen

First on my list, the helen, because it made me laugh.

The helen is a reference to Helen of Troy, the “face that launched a thousand ships”. One millihelen is the amount of beauty needed to launch one ancient Greek warship.

American author David Goines has further standardized the helen scale, defining a picohelen to be the amount of beauty required to “barbecue a couple of steaks and toss an inner tube in the pool”, while a terahelen will “launch the equivalent of one quadrillion Greek warships and make serious inroads on the welfare of the galaxy”.

Beard-second

The beard-second is a unit of length inspired by the light-year, but is considerably shorter. It is defined as the average length a beard grows in one second. Some sources define this length to be equivalent to 10 nanometres (about the size of a virus), but Google defines a beard-second to be 5 nanometres. I think Google’s measurements of average beard growth may include women.

As stupid as it sounds, beard-seconds would actually be useful in applications related to nanotechnologies such as integrated circuits.

My sternum is about 15 beard years from my chin.

Smoot

A smoot is a unit of length equivalent to the height of Oliver R. Smoot when he was a college freshman in 1958 (170 cm). As part of Smoot’s initiation to the Lambda Chi Alpha fraternity, Smoot and other freshmen were tasked with measuring the length of the Harvard Bridge by laying Smoot on the ground and using him as a yardstick.

They found the bridge to be 364.4 smoots long, plus or minus an ear. Smoot’s fraternity brothers also painted marking on the bridge at roughly 10 smoot intervals.

Smoots have turned out to be surprisingly useful. When the bridge was renovated in the 1980s, the local police asked that the smoot markings be maintained because they were useful markers for indicating the position of an accident on the bridge.

Google, of course, recognises the smoot as a unit of measurement.

Smoots make the list because Oliver Smoot himself took up a career in metrology, and even became the chairman of the American National Standards Institute, so the smoot is a unit with some pedigree.

Metrology can be a real drag.

Pirate Ninja

This is probably my favourite unit in the list. The pirate ninja is a unit of power invented by author Andy Weir for his best-selling novel The Martian.

In The Martian, Weir’s hero, astronaut Mark Watney, has to carefully monitor and balance his daily power usage if he is to survive being stranded on Mars. Watney decides that “kilowatt hours per sol” (sol = Martian day) is annoying and cumbersome to say so decides he’ll call them “Pirate Ninjas” instead, making one pirate ninja equal to one kilowatt hour per sol.

The reason that pirate ninjas are probably my favourite unit is that the Mars rover teams at the Jet Propulsion Laboratory ACTUALLY USE THIS UNIT! Taking inspiration from The Martian, instead of talking about the Curiosity rover’s power generation and usage in terms of watthours per sol, they now talk in units of “millipirate ninjas”.

All this faffing about doesn’t make much sense to me though, because one kilowatt hour per sol is just a unit of power, and could be easily be converted to watts. One pirate ninja is equal to 40.6 watts. Pirate ninjas are more fun though.

Give me 5 millipirate ninjas and I’ll shoot this rock with a laser.

Shake

The shake makes the list because, although it’s not an official unit, it is actually used in practice. Equivalent to 10 nanoseconds, the shake is a reference to “two shakes of a lamb’s tail”. It was invented during the Manhattan Project developing the nuclear bomb because 10 nanoseconds is a convenient time interval for nuclear physicists, being roughly equal to the time taken for one step in a nuclear chain reaction.

Shakes might also be useful for signal propagation time in integrated circuits.

Barn

Unlike the rest of the units on this list, the barn is an officially recognized unit. Like shakes, barns come from nuclear physics and the Manhattan project and are used to quantify the cross-sectional area of atomic nuclei. It’s a reference to “couldn’t hit the broad side of a barn” and was originally coined to prevent eavesdroppers realizing that scientists were talking about nuclear reactions, but has become a standard unit in particle physics. One barn is roughly equal to the cross-sectional area of a uranium nucleus.

The nuclear physicists also took the analogy further, referring to microbarns as “outhouses” and yoctobarns (10^-24 barns) as “sheds”.

The new nucleus is 1 barn wide plus or minus an outhouse…

The measure of things

While metrologists around the world work hard to carefully define and standardize the official SI units of measurement, this list shows that convenience and practicality, and a little bit of humour, will usually determine what and how a measurement is made. While I doubt we will be measuring milk in Hubble-barns and marathon times in microcenturies any time soon, imagination and creativity will continue to supply us with weird and wacky ways to measure the world around us. Though so far my colleagues have resisted all my attempts to define the power of our lasers in eye-meltyness…

Radio Telescope on Track

Posted on June 19, 2017 by drgozz

This post was originally published by Australia’s Science Channel on 29th July 2016 but was removed when the website was updated.

David Gozzard is a PhD student who has found himself on an interesting journey to remote Australia. In this blog, he shares some of the ~~fun~~ work he’s been up to!

When I started my PhD in experimental physics, I knew there would be a lot of travelling involved, mostly to conferences, meetings and workshops both in Australia and overseas. What I did not realize was how often I would find myself travelling to remote areas of Australia and South Africa to conduct field work. I’m not complaining. The field work is both challenging and rewarding, it gets me out of the lab, and it means I get to visit some of the world’s premier scientific facilities.

And that’s where I am now. After a four-hour flight from Perth to Sydney, a short hop from Sydney to Tamworth, and a two-hour drive from Tamworth to Narrabri (lugging two heavy cases full of scientific equipment), I find myself at the Paul Wild Observatory, home of CSIRO’s Australia Telescope Compact Array, the largest radio interferometer telescope in the southern hemisphere.

Antennas 1 – 5 of the Australia Telescope Compact Array.

Built in the 1980s, the Compact Array is a radio telescope comprising six 270-tonne
dish-antennas, five of which can be driven to various positions along a 3 km track in order to change their view of the sky. Although it’s not as famous as The Dish at Parkes, the Compact Array holds the distinction of being the most scientifically productive radio telescope in the southern hemisphere. In radio engineering, the plural of “antenna” is “antennas”. Biologists, calm down.

Me, driving antenna 3 during an array reconfiguration (see video below).

This is my 3rd trip to the Compact Array. I’m here to test equipment developed for the Square Kilometre Array (SKA) radio telescope. Radio telescope arrays like the Compact Array and the SKA need high-precision reference signals from atomic clocks to be transmitted to each antennas in order for the array to function properly. Over long transmission distances, the precision of these signals can become degraded and when that happens, the array fails.

On something the size of the Compact Array (6 km from one end to the other), this is not a problem; but for the SKA, which will have antennas located up to 150 km away from the centre of the site, signal degradation is a big problem. The equipment I have brought with me is designed to compensate for the degradation of the reference signal by measuring how the reference signal has been perturbed and modifying the transmission to compensate.

My signal stabilization test equipment setup at ATCA.

My supervisor and I have been developing this stabilization system over the past two years at The University of Western Australia, and we have tested its performance extensively in the laboratory. Now the time has come to plug it into a working radio telescope to confirm that it works in the real world!

Because this is a synthesis imaging telescope, every few weeks the antenna dishes are moved to different positions along a track to change how they image the sky. I was lucky enough to be allowed to take part in one of these array reconfigurations. Each of the six antennas weighs 270 tonnes and has a top speed of 4 km/h. Reconfiguration can take 1 – 2 hours depending on the extent of that day’s changes. Antenna 2 shown in the video was driven nearly 2 km in this reconfiguration job.

The Compact Array is the best facility to perform these tests because it was constructed with an almost unique receiver system that allows us to run the array using both its conventional reference distribution system and our stabilized reference system at the same time. Our system runs over an extra 77 km of fibre-optic cable to a communications hut and back. The telescope data from the conventional reference system can be compared directly with ours to see if the stabilization system is working as designed.

Me, sitting in the ATCA control room.

Working with the CSIRO team is an absolute pleasure. Everyone is very professional, they all know the systems they are responsible for insideout, and they are very helpful. The experiments that I have performed at the Compact Array would not have been possible without the efforts they made to accommodate my test schedule and the modifications I needed on some of the antennas.

This photo is the group of us who contributed to the work on this trip. The people in the photo are left-to-right: David Gozzard, Mike Hill, Sascha Schediwy, Peter Mirtschin, Jamie Stevens and Jock McFee (not pictured – Brett Lennon).

They also took a keen interest in the experiment itself. Many of the staff at the Compact Array reminisce about how it used to be, only a few years ago, when the site was buzzing with astronomers from Australia and around the world. Now, astronomers can operate the telescope remotely from Sydney or, in some cases, from the other side of the world. As a result, the onsite staff have seen their ranks halve as less support is needed. The engineers and other support staff miss being able to quiz astronomers about what they are using the telescope for, and what they are discovering.

Apart from the Compact Array itself, the observatory is home to a lot of Australian science history. The array occupies a site formerly used by the Culgoora radioheliograph (pictured below), which CSIRO used from the mid-60s through to the mid-80s
to perform groundbreaking studies of radio emissions from the Sun and solar outbursts.

One dish of the Culgoora radioheliograph.

Most of the 96 dish-antennas from the radioheliograph still surround the site in a 3 km wide circle. Within that circle are also the Sydney University Stellar Interferometer, until recently used to make measurements of the size of distant stars; the CSIRO Applied Physics Solar Telescope, which studied the visible light from the Sun in conjunction with the radioheliograph; the Birmingham Solar Oscillations Network Telescope, used to study churning gas inside the Sun; and an IPS Radio and Space Services telescope, which monitors solar outbursts to forecast how they will affect space craft and radio communications.

As I write this, my time at the Compact Array is coming to an end. My experiments have worked, the stabilization system has performed well, and I am preparing to report the results to the SKA Office. And the results are looking good. The system reduces signal fluctuations to one part in ten trillion, over a 1-second period. If your wristwatch
was that stable, after 300,000 years it would be off by less than one second. This is more than 10 times better than the stability required by the SKA.

Now I just have to pack up my equipment and get ready for the journey home.

Further reading

Measuring Up for World Metrology Day

Posted on May 19, 2017 by drgozz

This post is a modified version of a World Metrology Day article I wrote for Australia’s Science Channel.

Saturday 20^th May is World Metrology Day.

I’m not surprised if you hadn’t heard of it. I was three years in to a PhD in metrology before I found out we had a day for it.

Metrology is the science of measurement. It is an important foundation of other experimental sciences and is also a critical component of a nation’s ability to conduct business. Metrology considered to comprise three different fields:

Scientific metrology focusses on the definition of units of measurement (e.g. the kilogram, the metre, etc), how to actually make the measurements, and how to reliably trace a measurement back to an official reference.

Industrial metrology is about the application of measurement to manufacturing and other industrial and social applications. Industrial metrology is a very important factor in a nation’s engineering capability.

Legal metrology concerns the statutory requirements of measurement for trade, taxation, and protection of the public. Whenever farming produce is weighed, petrol is pumped, or shares are traded, the measurements (in these cases; weight, volume, and time) need to meet strict government controls on accuracy and precision.

Nearly every country has a metrology institute, involved in all of these important aspects of measurement. In Australia, we have the National Measurement Institute (NMI). America has the National Institute of Standards and Technology (NIST) and the UK have the National Physical Laboratory.

World Metrology Day is an international event commemorating the signing of the Metre Convention on 20^th May 1875. The Metre Convention established international cooperation to develop the metric system and the International System of Units (SI).

Signatories of the Metre Convention. Technically, America uses the metric system. Somebody should probably tell them.

Measure for measure

For the past three-and-a-bit years I have been pursuing a PhD in optical metrology — I use light to measure stuff.

In particular, I work on the transmission of atomic clock signals for use by radio telescopes and other space science experiments. Over the years, atomic clocks have become more and more precise, and today we need new technologies in order to transmit the atomic clock signals to another location for use in scientific or industrial measurements.

My metrology lab.

Measuring up

The next few years hold some exciting developments for metrologists. We will soon re-define two of the most basic measurements we use every day, the kilogram, and the second.

The SI system has seven basic units of measurement. These are: the metre, the kilogram, the second, the ampere, the Kelvin, the mole, and the candela. All other units that we use to measure stuff, such as volts or kilowatts, a derived from these basic units.

The second is currently defined using caesium atomic clocks. The caesium within the atomic clock emits microwaves at around 9 GHz, and this frequency is used as the “tick” from which the second is defined.

As atomic clocks have got better, another type of atomic clock that uses atoms of ytterbium have proved to be more stable and precise than caesium-based clocks. These clocks emit light at a frequency around 518 THz, that is, they tick at around 518 trillion times per second. In a few years’ time, ytterbium clocks might become the new way to define time.

The second, and most of the other SI base units, are defined using physical constants. For example, the metre is defined as the distance light travels in 1/299792458^th of a second. However, the kilogram is the only unit that is still defined by a physical object. A platinum-iridium ingot in a vault in France is defined to be the kilogram.

NIST’s copy of the kilogram.

Metrologists are working to find a better way to define the kilogram in terms of fundamental constants so that any metrology laboratory around the world can more easily make a precise and accurate measurement of the mass of the kilogram.

The leading contender is a device called a Watt balance that uses electromagnets to convert the mass of the kilogram into units of electrical power, Watts, which can be traced back to fundamental physical constants.

You can even download plans to build your own Watt balance. The US NIST released plans for a DIY Watt balance made out of LEGO. It’s millions of times less precise than NIST’s Watt balance, but about 10 to 100 times more precise than your kitchen scales (depending on how good your building skills are).

NIST’s LEGO Watt Balance

Metrology is an important part of our modern civilization. It is as fundamental to our way of life as electricity, or the internet. The progress of science and technology depends on the progress of our ability to make accurate and precise measurements.

50 Rules for Postgrads

Posted on February 25, 2017 by drgozz

This list was originally published as a humorous article in the UWA Postgraduate Student Association’s year book Postscript. It was inspired by the famous (infamous?) Skippy List. I have only done some of the things on the list, I’m not going to say which ones though…

50 things today’s postgrad is no longer allowed to do at university

Not allowed to imply that senior professors’ careers pre-date the discovery of the atom.
Not allowed to tell prospective students that “PhD” stands for any of the following:
– Parents have Doubts
– Probably half Dead
– Project half Done
– Permanent head Damage
– Potential heavy Drinker
– Probably hopelessly Deranged
No longer allowed to perform experiments on undergrads (even if rats are expensive and you grow attached to them).
Must stop telling new students that the Reid Library was actually a spelling error and everyone is too embarrassed to change it.
It is considered very unprofessional to add “in accordance with the prophecy” to the end of answers I give to questions when presenting at a conference.
“It is easier to beg forgiveness than ask permission” does not apply to getting ethics approval for an experiment.
The large rolls of aluminium foil in the lab are for experiments, not for making tinfoil hats to block government mind-probes, and I should stop telling students this.
No longer allowed to set joke questions in exams.
No longer allowed to create obvious patterns in the multi-choice exam answers
No longer allowed create an obvious pattern in the multi-choice answers for the first half of an exam, and then break that pattern in the last half to watch the students freak out (even if it would be hilarious).
Not allowed to attempt to purchase anyone’s soul using grant money.
When giving a reason for the failure of an experiment I must put forward a reasonable hypothesis, not:
– God
– Gods
– Witches
– Gnomes (there is no physics, it’s all gnomes)
Not allowed to sacrifice a chicken (or goat, suckling calf, mule, or virgin) to Odin so that He may look favourably upon my work (even if virgins are easy to come by in the physics department).
When visiting German colleagues, don’t mention the war.
Laser safety briefings must contain more than “Don’t stare into laser beam with remaining good eye.”
Drug running and prostitution are not acceptable ways to raise research funding.
Not allowed to ask “Do you want fries with that?” when given instructions by supervisors.
Must stop trying to hide Dr Seuss quotes in paper manuscripts.
Not allowed to turn my office into a ball pit…
Not allowed to turn anyone else’s office into a ball pit…
Plastic balls are no longer allowed on campus.
Despite the fact that people with a PhD are called “doctor”, they are not allowed to prescribe any form of medication.
When asked to attend a meeting in formal attire, I am not allowed to turn up in jeans and hoodie claiming that it is “the cultural dress of my people”.
Not allowed to wear costumes in the lab unless it is Prosh.
Office decorations must be limited and practical. I am not allowed to fill the room with inflatable novelties. (And not allowed to try and convince anyone that the Kiwi PhD student owns the inflatable sheep.)
When asked to “give a few words” to new postgrads, I am to assume that I should say more than a “few” words. (“Run you fools!” is also inappropriate.)
The correct course of action for an asphyxiating gas leak is not “hold my breath and hope for the best.”
Crucifixes do not ward off supervisors.
Stop sticking large googly eyes on laboratory equipment.
Not allowed to make liqueurs out of lab-grade ethanol.
No drinking in the lab.
No drinking in the office.
No drinking while teaching.
I may not trade laboratory equipment for any of the following:
– cigarettes
– booze
– sexual favours
– bootleg DVDs
– magic beans
Using an old Smirnoff vodka bottle as a water bottle and taking large, regular gulps is disturbing and I should not do it around new students or while teaching.
Putting red skittles in a prescription medicine bottle and swallowing regular handfuls while teaching is not appropriate.
I should not taunt humanities students just because they are doing “easy” subjects.
No longer allowed to scare international visitors with tales of how dangerous Australian fauna is (even if it’s true).
“No drinking of alcohol” is not a challenge to find other ways to imbibe.
Correct technical terms are to be used when teaching or preparing manuscripts. “Thingy”, “doohickey”, and “piece of shit” are not appropriate terms.
I must stop sending new students to the lab supply stores to ask for things that don’t exist.
Stop telling new students that Petri dish agar is edible (even though it is).
Wearing shorts under a lab-coat is disturbing because it looks like I am not wearing pants.
Do not replace the coffee in the lab coffee machine with decaf “to see what happens”.
No cooking in the lab.
Lab safety inductions do not need to begin with the “Safety Dance” song.
“To conquer the Earth with an army of flying monkeys” is not an appropriate response to being asked “what is this research for?” during a media interview.
Do not suggest to a colleague who has just had twins to name them “Alex, and the control.”
Beers are not to be stored in the specimen fridge. (Beers do not count as specimens.)
Magic eight-balls are not to be consulted for experimental procedures.
Student plagiarism is to be referred to the Head of School, not resolved “at dawn, on the field of honour.”
I am not allowed to start a betting pool on how long before the PSA president finally snaps and actually goes insane.

Off their trolley problem

Posted on October 24, 2016 by drgozz

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…)

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.

Gravitational Waves are Not the Ultimate Test of General Relativity

Posted on June 22, 2016 by drgozz

Last year’s ground breaking gravitational wave detections generated some of the widest media coverage of a scientific discovery to date. Many articles and reports described the detection as the “ultimate” test of general relativity, the “final” test of general relativity, or confirmation of Einstein’s “last” prediction. For a theory that is 100 years old, that was developed by one of the most celebrated physicists of all time, and has survived every experiment thrown at it, you could be forgiven for thinking that general relativity is done and dusted. However, general relativity is far from facing its “ultimate” test.

Gravitational Waves — another success for General Relativity, but not the final test.

Over the past century, general relativity has been put through its paces with some of the brightest minds on the planet developing new ways to test it. General relativity explains anomalies in the planet Mercury’s orbit around the Sun, why the universe cannot be static, and the way star-light is deflected by massive bodies like the Sun and distant galaxies. Predictions of general relativity have been tested using high-precision gyroscopes on satellites orbiting the earth and atomic clocks, by timing the orbits of distant neutron stars, and now, by the direct detection of gravitational waves. General relativity has survived every test, passing with flying colours. Even the fact that GPS functions properly is evidence of the success of general relativity.

But the nature of the scientific method means that no test that general relativity survives will be its ultimate test. Scientists will never stop testing general relativity until it fails. We know general relativity is not the final solution to a theory of everything, and we are reasonably certain that general relativity must fail at some point. While general relativity has been spectacularly successful in describing the large-scale workings of the cosmos (such as solar systems, galaxies, and the entire visible universe), it does not work on the small scale (atoms, nuclei, and fundamental particles), for which we need quantum mechanics. General relativity does not tell us what goes on inside a black hole, or at the moment of the Big Bang, because, in those situations, we are dealing with much smaller scales where quantum mechanics comes in to play. While we are very aware of general relativity’s ultimate limitations, this does not give us a very convenient starting point for developing a replacement theory. Like an engineer investigating the collapse of a bridge, if we can find the exact point of failure, we are better able to develop a solution. Because of this, many tests of general relativity today seek to determine the exact point at which general relativity breaks.

Most of the current approaches to breaking general relativity assume the devil is in the detail, and aim to make more precise measurements of previously tested phenomena. As more and more gravitational wave events are detected and studied, they will provide ever more stringent tests of the predictions made by general relativity. One research group wants to measure the precise orbits of different types of metal around the Earth, while another wants to time the fall of different types of atoms, things that general relativity says should show no difference between the different materials and atoms. The ESA’s ACES mission aims to make the most precise measurements ever of gravitational time dilation and gravitational redshift. If general relativity passes these tests, physicists will celebrate another success for a brilliant theory and for human intellect, and will then set about designing the next test. However, if, for any of these experiments, the predictions of general relativity do not match the data, physicists will celebrate the discovery of the breaking point, and the dawning of a new era in our understanding of the nature of the universe.

In order to get to space, throw yourself at the planet, and miss.

High precision space- and ground-based experiments aim to test General Relativity in minute detail

Rest assured, articles claiming “[Some experiment] is the ultimate/final test of Einstein’s greatest theory” are not yet a thing of the past.

Great Australians — Anthony Michell

Posted on June 20, 2016 by drgozz

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.

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 20^th 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.

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.

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.

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 20^th century, deserve to be amongst the first things a proud Australian should include on their list.

What the Detection of Gravitational Waves Means

Posted on June 20, 2016 by drgozz

Unless you live under a rock, the announcement in February of this year of the detection of Gravitational Waves by LIGO cannot have escaped your attention. Scientists around the world celebrated the achievement, and public curiosity about what all the scientists were yelling about was high enough that the world’s media ran the story for several days. Physicists and science communicators, whether they had anything to do with the discovery or not, were called upon to explain to the public what all the fuss was about.

If two Black Holes crash in deep space, and there is no detector to hear them, do they still make a Gravitational Wave?

The enormous release of energy from the collision of two Black Holes, detected for the first time

For a public that had never heard of Gravitational Waves before the announcement of their discovery, a key question that needed answering was, “So what does it mean?” Many scientists and science communicators did an outstanding job of answering this question, but their responses often left out an important element, that is, they did not answer the implied question, “what does it mean for me?”

Following the announcement earlier this week of a second Gravitational Wave detection (and another detection candidate), I want to take the opportunity to outline some of the ways in which the discovery of Gravitational Waves directly affects the average member of the public, but in the interest of providing a complete answer, I will first recap the importance of the discovery from a scientific perspective.

1) Amazing Achievement

First of all, the detection of Gravitational Waves is significant because it is direct confirmation of a prediction made 100 years ago by Albert Einstein. Einstein’s General Theory of Relativity is the best model physicists have for describing the action of gravity and the behaviour of the solar system, the galaxy, and the universe. Scientists constantly try to invent new experiments to push our understanding of the universe to the breaking point. It is by knowing the point at which our understanding of the universe fails that we are able to make the greatest progress. General Relativity has survived every test it has been subjected to for 100 years. Even the fact that GPS functions properly is a demonstration that Einstein’s General Theory of Relativity is correct.

In 1916, Einstein used General Relativity to predict that bodies orbiting each other, such as the Sun and Earth or two black holes, warp spacetime such that energy from the two bodies is carried away as ripples in the very fabric of the cosmos. These are Gravitational Waves, and their detection is not only another success for Einstein and General Relativity, but for the power of human ingenuity.

Gravitational Waves are ripples in spacetime caused by massive bodies in orbit

The LIGO detectors are the most sensitive instruments ever created and represent the culmination of 50 years of work by thousands of scientists. Although the first of the detected Gravitational Wave events represents an explosion 50 times more powerful than the power output of all the stars in the universe combined, the energy of the event has spread out and weakened during the 1.4 billion light-year trip to Earth, and so the LIGO detection represents the smallest amount of energy ever successfully detected. The very fact that humanity has the ability to detect Gravitational Waves is something we, as a species, can be proud of.

The Advanced LIGO detectors in Livingston and Hanford

2) A New Spectrum, a New Science

The two confirmed and one candidate Gravitational Wave detections represent the beginning of a new era in studying the universe, a new way of doing astronomy, Gravitational Wave Astronomy.

All of astronomy, and everything we have discovered about our universe through astronomy, has been done using light. Whether we use radio telescopes, optical telescopes, or gamma-ray telescopes, all of these devices detect energy from the electro-magnetic spectrum, they all detect some form of light. Gravitational Waves are not a type of light. They exist in a completely different spectrum.

The Gravitational Wave spectrum gives astronomers a completely new way of studying the universe because the properties of Gravitational Waves are very different to those of electro-magnetic waves. Unlike light, Gravitational Waves are not absorbed by matter. They pass unhindered through the Earth, interstellar gas clouds, and entire galaxies. Unlike light, they cannot be blocked by stuff getting in the way. Gravitational Waves allow us to see past the bright glare of galaxies, and through vast interstellar dust clouds to corners of the universe our other telescopes will never be able to see.

We can also use Gravitational Waves to study things that don’t emit light. As far as our current theoretical understanding tells us, the collision of two black holes, like the Gravitational Waves events seen so far, should not emit any light. These events, and events like them, can only be studied using the Gravitational Wave spectrum.

Since the end of its first, and now famous, observing run, LIGO has been undergoing upgrades that will roughly double the sensitivity of the detector. With this boost in sensitivity, and based on the three events detected so far, Gravitational Wave physicists expect LIGO to detect around one event per week when it is switched back on later this year. With that amount of data, Gravitational Wave Astronomy will become a field in its own right, and one that will revolutionize our understanding of the universe by studying regions of the cosmos previously invisible to us.

Gravitational Waves open up a new spectrum with which to study the universe

3) What it means for me

The detection is an amazing technological achievement and Gravitational Wave detectors are some of the most advanced pieces of equipment in the world. To be able to build their detector, scientists and engineers have had to invent new technologies along the way, and these new technologies have a huge range of spin-offs and applications that will impact on our every-day lives.

To build the LIGO detectors, super-reflective mirror coatings and polishing techniques had to be developed, vibration isolators that guard against everything from minor earthquakes to people coughing had to be built, hyper-precise lasers and sensitive read-out systems had to be invented, and all of this had to operate in hard vacuum, even special super-hard glues had to be formulated. To actually detect the signal, advanced analysis software had to be written. This is only a taste of the work involved. The complete list of innovations by Gravitational Wave scientists would take dozens of pages to list like this, and I don’t even know most of them!

With this type and variety of advanced technology in the works, it is almost inevitable that other applications would be found for the scientists’ innovations. Just one example from the University of Western Australia, where I am studying for my PhD, is the Rio Tinto Gravity Gradiometer. This new technology, which will detect ore bodies from an aeroplane by measuring tiny changes in the Earth’s gravitational field, spun-off from Gravitational Wave research at UWA.

This thing sits in the lab across the hall from me.

The VK1 airborne Gravity Gradiometer will detect ore bodies below the ground, and spun-out from Gravitational Wave research

Over the coming decades, technology originally developed for Gravitational Wave detectors will be worth billions of dollars, create many thousands of jobs, and will enrich our every-day lives for generations to come.

If you’d like to learn more, you can go here to watch PhD comics explain Gravitational Waves.

Great Australians — Ruby Payne-Scott

Posted on May 27, 2016 by drgozz

Southern Star

Ruby Payne-Scott is remembered as one of Australia’s most outstanding physicists. As well as contributing to other sciences, she was a pioneer of radio astronomy and made major discoveries about the nature of radio emissions from the Sun. Payne-Scott also has the distinction of being the first female radio astronomer.

Ruby Payne-Scott (28 May 1912 – 25 May 1981) — Physicist, pioneering astronomer

Early life and education

Ruby was born in 1912 in the town of Grafton, NSW. She demonstrated remarkable talent at school and moved to live with her aunt in Sydney, where she could get a better education. She was awarded honours in mathematics and botany, and won two scholarships to the University of Sydney where she studied physics, chemistry, mathematics, and botany. As was typical of the era, Ruby was often the only woman in her classes.

Research

Despite the prejudice and difficulty in getting a job that female physicists faced at the time (compounded by the Great Depression), Ruby’s excellent academic performance landed her a job as a physicist on the University of Sydney’s new cancer research project. One project she worked on was to determine the effect that the Earth’s magnetic field had on the vital processes of living beings. Working with William Love she cultivated chick embryos in magnetic fields up to 5000 times stronger than the Earth’s field. They found no observable differences in the chicks and determined that the magnetism of the Earth had little or no effect on living creatures.

The cancer research project closed down in 1935, and Ruby was forced to take one of the few career options open to educated women at the time, teaching. She completed a diploma of teaching and started working at a school in South Australia. Ruby was constantly alert for ways to get back into physics and eventually managed to land a job with Australian Wireless Amalgamated, a major hirer of physicists. Although she was hired as a librarian, Ruby managed to get involved in some research projects in the company’s standards laboratory and eventually worked her way into full-time research.

In 1939, Australia, following Britain’s lead, declared war on Germany. The CSIR (the precursor to the CSIRO) was charged with developing an Australian radar capability. As happened in Britain and the USA, mobilization for war created a shortage of trained men and provided women with the opportunity to break into jobs and careers they were previously bared from. Ruby and another woman, Joan Freeman, managed to get hired to work as researchers in the CSIR’s new Radiophysics laboratory. The women excelled in their roles, under the leadership of another great Australian physicist, Joe Pawsey, and both Ruby and Joan later commented that their colleagues treated them as “one of the boys”. The two women mainly had to deal with discrimination from administrators and petty bureaucrats who imposed absurd and unfair rules such as banning women from smoking or wearing shorts, rules which Ruby took the lead in breaking. Ruby even married her Husband, Bill Holman Hall, in secret in 1944 because married women were not allowed to hold permanent positions in government agencies.

Wartime radar research in Britain had discovered that the Sun occasionally produced significant amounts of radio waves. Excited by this, in their spare time Ruby and Joe Pawsey ran some experiments to follow up on this discovery, but did not have the right equipment to make the observations. When the war ended the Radio Physics laboratory was due to be scrapped, so the team put together an application to continue as a radio physics research division, concentrating on rain making and radio astronomy. At the time, radio astronomy was a very new field of research and the astronomy community showed very little interest. Despite this, the CSIR decided to fund radio physics and Australia remains a world leader in radio astronomy to this day.

Along with Joe Pawsey and Lindsay McCready, Payne-Scott used decommissioned radar equipment to make detailed radio-frequency observations of the Sun. This small team was the first to construct a radio-astronomy interferometer. Radio interferometers greatly increase the resolution of their observations by using a long baseline between two or more radio antennas. The CSIR team managed to construct an interferometer using only one antenna.

Great TV reception... Just had to wait for Australia to get TV.

Decommissioned radar antenna at Dover Heights, run by CSIR Radiophysics.

The radar antenna they were using was a coastal installation mounted on a sea-cliff. The antenna received radio signals directly from the Sun but also from reflections off the sea below. This simulated a baseline of around 200 metres between two antennas and allowed Payne-Scott, Pawsey and McCready to determine that solar radio radiation was coming from patches of the Sun that had sun-spots, a major discovery that boosted Australia’s international scientific reputation. The team also showed that the Sun’s corona has a temperature of over a million degrees centigrade, a phenomenon that remains a mystery to astrophysicists. Payne-Scott is also credited with the discovery of type I and type III solar outbursts.

Built to defend against the land of the rising Sun.

Dover heights sea-cliff interferometer — used to study the Sun

Workplace activist and career cut short

Throughout her time at the CSIR and its successor the CSIRO, Payne-Scott was an active advocate of equal rights and pay for women. She fearlessly and vocally opposed women’s workplace restrictions and pay reductions, clashing with CSIRO chairman Sir Ian Clunies Ross on several occasions. Eventually her secret marriage was discovered by CSIRO administrators and she was demoted to a temporary position. Payne-Scott left the CSIRO for good in 1951 (aged 39) to give birth to her son Peter.

Later life

Payne-Scott had a second child, a daughter named Fiona, and in 1963 returned to teaching. She retired in 1974 and died in 1981 at the age of 69.

Today, Ruby’s legacy is remembered in the CSIRO by the Payne-Scott award which is given to support the careers of women researchers. Her influence on radio astronomy and her discoveries means that her name is known by a large section of the Australian astronomy community, though they may not be completely aware of how hard Ruby had to fight to be able to do her ground-breaking research.

Google celebrated Ruby’s 100th birthday.

In 2012, on what would have been her 100^th birthday, Ruby Payne-Scott was celebrated with a Google doodle. However, this great Australian is still completely unknown to the majority of Australian people. Ruby, her research, and her fight for women’s rights deserves greater recognition.

More information on the life and work of Ruby Payne-Scott can be found at the CSIRO Staff Association, National Archives, or Payne-Scott’s Wikipedia page.

The Value of a PhD

Posted on April 27, 2016 by drgozz

Stop telling me to “get a real job”: PhDs drive economic growth, as well as the progress of human knowledge

As a PhD student, questions I am often asked very shortly after “What do you do for a living?” include “What’s the point of that?” and “So when are you going to get a real job?” Science communication practice over the past couple of years (such as competing in 3-Minute Thesis and FameLab) has helped me to come up with concise answers to the first of these questions that satisfy the majority of my interrogators. I am also quick to point out that studying for a PhD is a real job and to explain the benefits of PhDs and academics to the nation. However, people often seem to disagree with my assertions about the contribution of PhDs to the public and to the economy, to the extent that many will repeat the question the next time they see me.

PhDs in your life

Everywhere you look you will find technology that was invented or developed by people with PhDs. The technologies your smartphone and computer are based on cannot be built without a working knowledge of quantum mechanics, GPS would fail without knowing how to apply Einstein’s General Theory of Relativity, and the medical practices that keep you healthy are only possible due to our understanding of the immensely complex system that is the human body. Tens, hundreds, or thousands of PhDs have contributed to the technologies and services that you rely on and enjoy every day. You owe your health and wellbeing to the diligent research of generations of PhDs.

A PhD student has many similarities with a tradesman’s apprentice. The apprentice/student learns the tools and skills of their trade guided by the knowledge and experience of their master/supervisor, producing useful work as they learn. Just as we expect an apprentice electrician or machinist to quickly gain a measurable level of competence, we expect PhD students to make significant contributions to scientific and technological progress from early on in their candidature (continuing this analogy, PhDs have a “post-doc” period similar to an apprentice’s journeyman years).

A common accusation I received before I learned to explain the significance of my work quickly (and still receive on occasion) is that my chosen field of research is so narrow that it is of no use or interest to anyone else. It is often the case that one scientist’s research can seem so focussed on one objective that it has no impact elsewhere. This is a matter of necessity. We live in such a rich and complicated cosmos that, today, the only way one person is able to make significant progress is to pick a direction and attack it. However, the accusation that their research is of no wider significance fails to take into account that we scientists do not work alone. We work in a team, playing our individual part in a global human effort to understand the world we live in and to improve our quality of life. No science exists in isolation, and each narrow field of research contributes to the growing expanse of collective human knowledge and progress.

But the accusation of narrowness is false too. The seemingly tight focus of my research is built upon a broad foundation of other skills and knowledge. I view my growing expertise in my field as something resembling a pyramid, with the narrow apex supported by a broad and sturdy base. When I finish my PhD, I will be the world expert in optically-sensed stabilized microwave reference dissemination systems, I will be a world expert in stabilized time and frequency transfer, an expert in microwave and optical transmission, fibre-optics, and radio-telescope engineering, all supported by a strong competence in electronics, computer aided design and simulation, and a variety of fields of physics including wave mechanics and General Relativity.

This only took slightly less effort than the Giza one.

Focused research is supported by a broad background of skills and expertise.

The job of a researcher is to seek answers and improve our understanding of the world we live in, to look forward and drive our progress as a species. Scientific research is the only defence humanity has against threats to our way of life, or even our survival.

The economic argument

I have met many people who, disconcertingly for me, view PhDs as a waste of taxpayers’ money. Indeed, government treasuries are often keen to see proof that their investment in research and in PhDs is not being wasted, or couldn’t be better spent elsewhere. In the United States, Congress has demanded that the National Science Foundation “better articulate the value of grants to the national interest.” Recognizing that failure to communicate the return-on-investment of grants places us at risk of losing government and public support, researchers have challenged themselves to come up with scientific evidence on the impact of government investment in research. Late last year, a study published in Science demonstrated a significant way in which PhDs (and thus, the government grants that supported them) make an impact on the economy.

The study showed that PhDs disproportionately gained jobs in high-productivity, high-payroll establishments performing research and development, firms that that typically have a much greater economic impact. The study also showed that the majority of PhDs gained jobs close to where they had studied. Together, the evidence shows that PhDs make a substantial contribution to the economy that supported them, and that investment in PhD funding and research grants is well-founded.

More broadly, there is much historical evidence to show that research drives economic growth. Scientific and technological research produces new technology and ideas, that create new products and services, that create new jobs.

PhDs are no less real jobs than a trade apprenticeship. PhD students work hard to contribute not just to the economy, but to increasing knowledge and progress for the benefit of all humanity.