Quantum weirdness passes the atomic walk test

Confused? You will be. Inga Nielsen/Shutterstock

Quantum mechanics is a funny beast. On one hand it is a hugely successful theory, providing predictions of unrivalled accuracy across the natural world. On the other, it is a theory famed for its weirdness and failure to make sense in everyday terms: under quantum mechanics, light is both a particle and a wave, cats can be both dead and alive, and objects at the opposite ends of the galaxy exert a “spooky action-at-a-distance” on one another.

But is this weirdness really necessary? Could there be a theory more fundamental than quantum mechanics and yet in which only sensible, “non-weird” rules apply?

In particular, if we could find a theory that was “realistic”, that is, based on an intuitive reality in which objects have well-defined properties – for example dead or alive, but not both at the same time – we would solve a whole host of quantum-mechanical headaches in one swoop. But is a realistic description of nature possible? Can we have a theory which does the same job as quantum theory, and yet is free from all its weirdness?

Concrete tests

A key contribution to this discussion came from John Bell in 1960s. In addition to realism, Bell considered theories with a second very natural constraint – locality. Locality is the notion that far-apart objects cannot influence one another instantaneously. Newton described its opposite, non-locality, as “so great an Absurdity that I believe no Man who has in philosophical Matters a competent Faculty of thinking can ever fall into it”.

Bell proposed an experiment involving two particles far removed from one another. He proved that, according to all local realistic theories, a certain sequence of measurements on the two particles always return results that, when added together, give a number less than or equal to one. This relationship is known as a Bell’s inequality. Furthermore, Bell predicted that under quantum mechanics, the exact same sequence of measurements can give a value that exceeds one.

Here then was a concrete, testable difference between quantum mechanics and the whole class of theories built on local realism.

Since the initial work of John Clauser and Alain Aspect, this difference has been experimentally tested – with increasingly large distances between the particles. The result is clear: actual measurements of Bell’s ideas give a value higher than one. As this is beyond the realm of possibilities with local realistic theories, such theories cannot be viable descriptions of nature.

Doing the quantum walk

Bell’s tests involve multiple, separated objects and rule out theories which are both realistic and local. But for a single object, locality (its distance from another) isn’t an issue. So could it be that realism and realistic theories can still help us out of quantum paradoxes involving only single objects, such as Schrödinger’s cat?

This is the question addressed in new experiments by my colleagues at the University of Bonn. The team, led by Andrea Alberti, used lasers to first trap a single caesium atom and then drag it back and forth in a sequence of steps known as a “quantum walk”.

An atom takes a quantum walk through many paths at once. Robens et al. Phys. Rev. X 5, 011003, CC BY

Under a realistic description of its motion, the atom has a well-defined position at every point in time, even when we are not looking at it. Provided that we also assume it’s possible to measure the atom’s position without disturbing it, this property leads to another testable inequality – the Leggett-Garg inequality.

By looking for where the atom is not, rather than where it is, the Bonn team were able to perform the most faithful Leggett-Garg test to date. Their results show a clear victory for quantum mechanics – contrary to realistic theories and our own intuition, the quantum-walking atom has to be considered as being in two places at the same time.

A quantum future

Taken together, results like these make the hope of replacing quantum mechanics with something more “sensible” appear futile. By insisting that our new theory be realistic, we inevitably end up with weird results that include the ability to act on distant objects or measurements that disrupt what they are trying to record. And these make our new theory at least as weird, if not weirder, than the quantum theory we are trying to replace.

But rather than feel disappointed at losing our easy way out from quantum’s difficulties, we should feel emboldened in our confidence in quantum mechanics. The measured violations of Bell and Leggett-Garg inequalities stem from the quantum-mechanical properties of entanglement and superposition, respectively. By embracing these properties, we are learning to construct new technologies such as quantum computing, quantum imaging and quantum encryption.

More fundamentally, future research will extend these quantum tests to include ever larger objects. We are confident that quantum mechanics holds at the smallest of scales. Likewise, a realistic description fits the behaviour of objects in our everyday experience. But somewhere in the middle, something has to give, and the sharp lines thrown by these inequalities will be central to investigating boundary between the everyday and quantum worlds.

Are you overweight? The clue's in your poo

Baby it's warm inside ... we have 200 microbes for every human cell Agricultural Research Service

We are all populated by microbes – helpful or otherwise – which form a community known as a microbiome. Recent research by Ryan Newton and co-workers has shown that sewage-based analysis of the human microbiome can be used to diagnose health issues at a population level.

Large-scale monitoring of human populations and their activities takes many forms, from satellite imagery to censuses, providing data that can inform future policies. At this scale, we can collect and store data to assess the health of a nation. Projects such as BiobankUK and the 100,000 genomes project aim to fully describe human genetics and health at the cellular and molecular level, whilst revealing information at an individual and population level. This will result in the creation of a UK disease map, possibly linked to genetic information and factors that significantly affect health.

These projects focus on the human genome – yet we are not just human. Each of us is populated by microbes: bacteria, viruses, fungi and protozoa. Bacterial cells alone outnumber our own by a factor of 20. No one has estimated the number of viruses, but we expect between ten and a hundred times more than the bacteria. In the body, microbial genes outnumber human genes by a factor of 200.

We are now able to look not only at the numbers of microbes in the body, but can also find out what they are and determine their functions. DNA sequencing on very large scales indicates which bacteria dominate different environments and different processes. This sequencing defines the identity of the microbes. When targeted correctly, it can also define function at a molecular level. This is particularly useful in describing the human microbiome and its value to human health.

The microbes that form our microbiome provide protection against disease, top up our immune system, help metabolise our food into simpler more useful compounds and provide some essential nutrients such as vitamin K. The genetic profile of bacteria in faeces provides individual microbial fingerprints. This shows that the microbiome in all humans has a shared essential microbial function whilst having some variability in its microbial composition.

Whodunnit? Microbes in our gut have a distinctive ‘fingerprint’ that reveals their identity

Gut microbes also vary with progressing age, dietary changes, disease states and across differing human populations. Changes in the diversity of the microbiome are associated with certain chronic illnesses such as inflammatory bowel disease. By looking at the microbial profiles of bacteria in the colon we can even show a difference between people with Crohn’s disease and irritable bowel syndrome compared to people with ulcerative colitis.

This type of diagonistic analysis has now been taken a step further. Whilst recognising that faeces are a proxy for the gut microbiome within and among human population, Ryan Newton and co-workers examined sewage samples and compared them to human faecal samples. They showed that sewage effluent accurately reflects a composite faecal microbiome from human populations not only at an individual level but over different demographic scales – city, country, or continent – using 71 cities in the USA as a sampling ground.

Sorting the fat from the lean

Among the core set of organisms detected, significant variation was seen at a population level rather than at an individual level. This variation clustered into three primary community structures distinguished from different groups of microbes: Bacteroidaceae, Prevotellaceae, or Lachnospiraceae/Ruminococcaceae. These distribution patterns reflected human population variation and even predicted whether samples represented lean or obese populations with 81 to 89% accuracy.

So why not just observe the “fat and lean” by sitting at a busy railway station in disguise rather than extract the bacteria from sewage? Well, not everyone in the population will pass the detective’s observation point but almost all will submit their sample to the sewer, to be subjected to sewage molecular “satellite” imagery. And sewage can be used to analyse many more health issues than simply the weight of the population.

Of course there will be limitations to this approach. But as a means for analysing data at a city, country or continental level, the limiting factor may simply be how many samples we can collect and analyse.

The full potential of this technique has yet to be realised but advances in sequencing and bioformatics – coupled with increasing sensitivities of analysis – could make sewage monitoring a routine part of health analysis. This could be used to inform policy at local and national scales and ultimately could even benefit personal health strategies.

Dawn of a new era: the revolutionary ion engine that took spacecraft to Ceres

I've seen the future, and the future's blue. NASA

The NASA spacecraft Dawn has spent more than seven years travelling across the Solar System to intercept the asteroid Vesta and the dwarf planet Ceres. Now in orbit around Ceres, the probe has returned the first images and data from these distant objects. But inside Dawn itself is another first – the spacecraft is the first exploratory space mission to use an electrically-powered ion engine rather than conventional rockets.

The mysterious bright spot of Ceres seen as Dawn approaches. NASA

The ion engine will propel the next generation of spacecraft. Electric power is used to create charged particles of the fuel, usually the gas xenon, and accelerate them to extremely high velocities. The exhaust velocity of conventional rockets is limited by the chemical energy stored in the fuel’s molecular bonds, which limits the thrust to about 5km/s. Ion engines are in principle limited only by the electrical power available on the spacecraft, but typically the exhaust speed of the charged particles range from 15km/s to 35km/s.

What this means in practice is that electrically powered thrusters are much more fuel efficient than chemical ones, so an enormous amount of mass can be saved through the need for less fuel onboard. With the cost to launch a single kilogramme of mass into Earth orbit of around US$20,000, this can make spacecraft significantly cheaper.

This can be of great benefit to commercial manufacturers of geostationary satellites, where electric propulsion can allow them to manoeuvre adding new capabilities to the satellite during its mission. However, for scientific missions such as interplanetary travel to the outer regions of the Solar System, electric propulsion is the only means to carry useful scientific payload quickly across the enormous distances involved.

Inside an ion engine. NASA

Electric space power

There are three broad types of electric propulsion, depending on the method used to accelerate the fuel.

Electrothermal engines use electric power to heat the propellant either by passing a current through a heating element, a configuration known as a resistojets, or by passing a current through the hot ionized gas or plasma itself, an arcjet.

Electromagnetic engines ionise the propellant by turning it into an electrically conductive plasma, which is accelerated via the interaction of a high electrical current and a magnetic field. Known as pulsed plasma thrusters, this technique is in fact quite similar to how an electric motor works.

Electrostatic engines use an electric field generated by applying a high voltage to two grids perforated with many tiny holes to accelerate the propellant, called a gridded ion engine, which is what powers Dawn. Another electrostatic design is the Hall effect thruster, which operates in a similar fashion but instead of high voltage grids generates an electric field at the thruster’s exit plane by trapping electrons in a magnetic field.

Half a century in the making

The concept of electric propulsion has been around for 50 years or more, but was deemed too experimental to commit to major projects. Only now is it beginning to find real applications. For example, keeping geostationary satellites in their correct orbit, to counteract the aerodynamic drag from the very tenuous atmosphere 200km above the Earth. Or interplanetary missions such as Deep Space 1 – the first experimental mission to use ion engines, it was originally intended as a technology demonstrator but performed a successful fly-past of the asteroid 9969 Braille and the comet Borrelly 15 years ago.

Another very successful mission using ion engines was the ESA Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite which for four years until 2013 was able to map in unprecedented detail the Earth’s gravity field.

The Dawn spacecraft, equipped with large solar panels to power its electrical engine. NASA

Future designs

Now that electric spacecraft engines have entered mainstream use, they look set to reduce the cost of deploying satellites. With compact ion engines onboard, satellites can raise themselves from low Earth orbit to their final geostationary orbit under their own power. This will save enormous amounts of fuel required to lift the satellite through conventional chemical rockets, and allow the use of much smaller launch vehicles which will save a lot of money. Boeing was the first off the blocks in 2012 with an all-electric version of their 702 platform satellite fitted with xenon-powered gridded ion engines, and other satellite manufacturers are following suit.

Currently all electric power designs use xenon gas as the propellant, but the search is on for alternative propellants since xenon is enormously expensive and in limited supply. But electrical power is here to stay, and over the longer term, space tugs and even manned missions to Mars based on nuclear electric propulsion will be the next on the drawing board.

New nanomaterials will boost renewable energy

Fossil fuels can only go so far towards meeting our burgeoning energy demands Shutterstock

Global energy consumption is accelerating at an alarming rate. There are three main causes: rapid economic expansion, population growth, and increased reliance on energy-based appliances across the world.

Our rising energy demand and the environmental impact of traditional fuels pose serious challenges to human health, energy security, and environmental protection. It has been estimated that the world will need to double its energy supply by 2050 and it is critical that we develop new types of energy to meet this challenge.

Fuel cells usually use expensive platinum electrodes, but a non-metal alternative could be an affordable solution for energy security. Fuel cells generate electricity by oxidizing fuel into water, providing clean and sustainable power.

Hydrogen can be used as the fuel. First, hydrogen is split into its constituent electrons and protons. Then the flow of electrons generates electrical power, before the electrons and protons join with reduced oxygen, forming water as the only by-product.

This technology has high energy conversion efficiency, creates virtually no pollution, and has the potential for large-scale use. However, the vital reaction which generates reduced oxygen in fuel cells requires a catalyst – traditionally a platinum electrode. Unfortunately, the high cost and limited resources have made this precious metal catalyst the primary barrier to mass-market fuel cells.

The high cost of platinum can make electrodes – as well as engagements – prohibitively expensive. 1791 Diamonds, CC BY

Ever since fuel cells using platinum were developed for the Apollo lunar mission in the 1960s, researchers have been developing catalysts made from alloys containing platinum alongside cheaper metals. These alloy catalysts have a lower platinum content, yet commercial mass production still requires large amounts of platinum. To make fuel cells a viable large-scale energy option, we need other efficient, low cost, and stable electrodes.

We previously discovered a new class of low-cost metal-free catalysts based on carbon nanotubes with added nitrogen, which performed better than platinum in basic fuel cells. The improved catalytic performance can be attributed to the electron-accepting ability of the nitrogen atoms, which aids the oxygen reduction reaction. These carbon-based, metal-free catalysts could dramatically reduce the cost of commercialising of fuel cell technology. Unfortunately, they are often found to be less effective in acidic conditions – the typical conditions in mainstream fuel cells.

Using carbon composites with a porous structure to increase surface area and nanotubes to enhance conductivity, our latest research demonstrates that our nanomaterials are able to catalyse oxygen reduction as efficiently as the state-of-the-art non-precious metal catalysts – and with a longer stability. This first successful attempt at using carbon-based metal-free catalysts in acidic fuel cells could facilitate the commercialisation of affordable and durable fuel cells.

In addition to fuel cells, these new metal-free carbon nanomaterial catalysts are also efficient electrodes for low-cost solar cells, supercapacitors for energy storage, and water splitting systems which generate fuel from water. The widespread use of carbon-based metal-free catalysts will therefore result in better fuel economy, a decrease in harmful emissions, and a reduced reliance on petroleum sources. This could dramatically affect life in the near future.

Warning: the truth behind handshake-sniffing may bum you out

"Lovely day for it." "Woof yes!" Craig Roberts

As we all know, a firm handshake is important in making a good first impression. It’s a sure sign of physical strength and, rightly or wrongly, we use it make all manner of judgements about character, personality and sincerity.

New research now suggests that we take away much more than this – quite literally – because shaking hands may also be a way that we smell each other. As you may have read elsewhere, an Israeli team published a paper that showed that handshakes transfer aromatic compounds thought to be involved in social assessment – that is, making judgements about someone else by virtue of how they smell.

‘Don’t forget to sniff!’ Isa Sorensen, CC BY-SA

They analysed the chemical compounds present on clean surgical gloves and those that had been worn during a single handshake with the bare hands of ten volunteers. A range of chemical compounds were transferred, including some involved in animal interactions or already known to occur in human skin secretions.

So handshakes transfer smelly compounds. And how often we smell our hands following a handshake depends on who we greet. By secretly filming 150 participants, the researchers found that both men and women spent more time smelling the hand they used in the handshake when they greeted someone of the same gender. When they greeted a member of the opposite sex, they spent more time smelling their non-shaking hand.

Smell and social interaction

These new results add to accumulating evidence that our sense of smell plays an important part in social interactions. We can detect whether someone is sick or healthy through their body odour, or whether they are fearful, for example. Women place particular value on smell when judging suitability of potential partners, and prefer armpit odour of men who, among other qualities, are more genetically compatible or socially dominant.

In turn, men find women’s armpit odour more attractive when women are close to ovulation and exposure to vulvar scents collected around ovulation increases their testosterone levels, suggesting that scent might prime men for competition over a fertile woman. Interestingly, women respond to fertile odour in just the same way, suggesting they are also sensitive to smells of potential competitors.

So what exactly might we be assessing when we check out hand odour, and what might we use that information for?

Smell is usually thought to be important in sex and attraction, so it was surprising that sniffing of the shaking hand increased the most after greeting someone of the same sex. The researchers suggested that this could be a way to assess the competition (though they admit they did not ask about sexual orientation of the participants).

That would not completely rule out using hands to sniff out potential partners. Reactions to smells can change depending on context, so perhaps people increase focus on the opposite sex in more socially relevant settings, or if they are single and searching for someone special.

But it’s not about the hands

One problem with all this is that it remains unclear whether there is some particular communicatory value in the smell of a hand. So far as we know, there are no special secretory glands that are unique to the hand – the compounds present on hands are likely to be much the same as those that occur on many other parts of the body.

Bad plan? okili77

Yet we do use our hands to touch other parts of our body which produce specific and localised odours, including our lips, hair and, of course, more intimate areas. The researchers did not provide evidence that these are the source of some of the transferred smell compounds, but it seems plausible. Indeed, studies aiming to promote handwashing report all kinds of bodily traces, including faecal bacteria, on hands of ordinary people on the street.

This could provide the key to understanding hand-smelling. A simple handshake is a world away from the greeting ceremonies of other mammals. They are unconstrained by the social niceties of observing personal space and partake in abundant close-up sniffing, very often in the ano-genital area.

We simply don’t get to do this until we enter an intimate sexual relationship. But because hands wander, they pick up these more intimate odours and make them accessible in a socially acceptable way. In other words, offering a handshake could just be a polite and modern version of inviting someone to “sniff my butt”.

A year after MH370 vanished we have only theories, but here's why the search must go on

Messages left without answers. مانفی, CC BY-SA

The disappearance of Malaysia Airlines flight MH370 a year ago has led to one of the largest search exercises in history. The 140-tonne aircraft and all its 239 passengers and crew remain missing, and the search continues across 17,000km² of ocean up to 5km deep. For comparison, we knew within 20km where the 50,000 tonne Titanic sank in 1912, in water 4km deep – and even then it took 73 years to find it.

A steel ship is much easier to find than an aluminium aircraft because it has a far larger effect on the earth’s magnetic field and so is easier to detect. More obviously, locating something as big as a cruise liner based on a fairly good knowledge of the location is much easier than finding a much smaller aircraft in a large area of the Indian Ocean.

Why don’t we know where MH370 went, wasn’t it being tracked? Near to major cities and population centres, state air traffic control uses primary radar – which locates objects using reflected radio waves. But radar’s range is only a few hundred miles, and while airliners carry their own radar this is calibrated for detecting storms and mountains, not other aircraft.

Radar only takes you so far

Beyond radar range we use secondary surveillance radar or SSR, this is built upon a World War II technology called “IFF” or “Identify Friend or Foe” and receives a coded signal from a ground station or another aircraft, then transmits back another coded signal which can include identity, position, altitude and speed. MH370 was equipped with ADS-B (Automatic Dependent Surveillance – Broadcast): a state-of-the-art secondary radar technology, detectable by ground stations and other aircraft.

Most accidents will cause power to the transponder to fail, but there are two more systems in the event of an emergency. Underwater, the Flight Data Recorder (the “black box”) emits an audible beacon for about 30 days. When on the surface Emergency Locator Transmitters transmit location for 1-2 days by radio. Throughout the flight, there’s also an automatic maintenance messaging system called ACARS which works through a satellite communications antenna.

In the case of MH370, while the transponder and ACARS had been shut down, the satellite antenna continued to respond to hourly handshake signals. This suggests that the disappearance of MH370 was caused by unlawful interference – but probably not by the captain. Why? If you asked a commercial pilot to commandeer an unfamiliar aircraft and fly it somewhere undetected, they would disable the ACARS, transponder, and radios – but without more detailed type knowledge probably wouldn’t disable the more obscure satellite communications antenna.

The search so far. Andrew Heneen, CC BY

As the person on board with the greatest systems knowledge was the captain, this makes him an unlikely candidate for a hijacker. Also, with more than 18,000 flying hours (the minimum to command an airliner is 1,500) and an examiner’s qualification on the Boeing 777 link, he was capable of flying anywhere Asia and landing safely without assistance.

This suggests that if anyone was flying the aircraft, it probably wasn’t him. That said, this is only my opinion: Captain Zaharie Shah was in the right place after all, and had allegedly made no social plans after March 8, 2014link. That could be taken as suspicious.

The fact we have any idea where the aircraft was headed at all is due to brilliant mathematics by engineers at Inmarsat. They analysed the satellite handshake signals – not normally used for navigational purposes – and came up with an approximate flightpath, ending about the same time the aircraft fuel would have been expected to give out. That narrowed the search area to “only” 17,000km². They didn’t find the needle, but they offered a clue as to in which haystack it could be found.

To track or not to track

There have been calls from many quarters for tracking systems to be fitted to commercial aircraft that cannot be turned off, or for detachable, floating location beacons as fitted onto some military aircraft. It’s important that these don’t endanger the aircraft – I’ve had to turn off a transponder in-flight following a systems failure, so this isn’t a hypothetical concern. But creating transponders unable to threaten the aircraft is a solvable problem.

This will be expensive, but airlines won’t complain so long as it is mandatory: regulations that affect all competitors equally will just add a little to the cost of all airline tickets. Unions worry that some options – for example transmitting flight data by satellite link – could grow into an “spy in the cockpit” for management to monitor them, but the same concern was resolved with Flight Data Recorders and Cockpit Voice Recorders by making use of the data without the crew’s permission illegal for any purpose other than safety.

Ultimately, we must keep looking. It’s not acceptable that an aircraft with 239 people on board can simply vanish. We must find out why – not to allocate blame, as that doesn’t really matter: indeed if it’s known that blame will be allocated people are less likely to co-operate with any inquiry. What matters is learning how to avoid similar accidents in the future.

For this reason, if no other, it remains vital that we find MH370, and when found, the evidence retrieved and analysed.

You probably haven't heard of these five amazing women scientists – so pay attention

Now for the science. isak55/Shutterstock

All week I’ve been intrigued and inspired by posters appearing in my department that depict truly great scientists, mathematicians and engineers. Few of them were known to me or my fellow students, yet their achievements include revolutionising algebra, developing the first treatment for leukaemia, and discovering fundamental processes in physics.

Their only common characteristic? They are women, and their appearance on the walls marks International Women’s Day. Try to recall a woman scientist and Marie Curie may be the first and perhaps only name that springs to mind. This is a shameful state of affairs, when for more than a century scientists who happen to be women have reached great scientific heights, despite the many barriers they faced on account of their gender.

So here are five women whose amazing discoveries and contribution to science should be as well-known and respected as those of Marie Curie.

Rosalind Franklin – crystallography

Rosalind Franklin. Jewish Chronicle Archive/Heritage-Images

Only now is Rosalind Franklin’s (1920-1958) reputation recognised: a chemist, she was responsible for much of the X-ray crystallography research that was critical to the discovery of the famous double helical DNA structure.

She worked in a climate that was far from inclusive to women; her fellow scientists' attitude towards her are typified by James Watson’s book The Double Helix in which he is condescending throughout and refers to her as “Rosy”, a nickname she was known to dislike. Tragically, Franklin died from ovarian cancer in 1958, aged just 37. Four years later Francis Crick, James Watson and Maurice Wilkins, were awarded the Nobel Prize in Physiology or Medicine and famously omitted Franklin from their acceptance speech.

Lise Meitner – nuclear physics

Lise Meitner in 1906. Churchill College Cambridge

Lise Meitner (1878-1968) was an Austrian physicist and the second woman to obtain a doctorate in physics at the University of Vienna in 1906, and the first woman in Germany to assume position of a full Professor of Physics in 1926. The annexation of Austria by Nazi Germany in 1938 forced Meitner to flee Germany due to her Jewish descent.

Meitner and Otto Hahn discovered nuclear fission in 1939, yet the 1944 Chemistry Nobel Prize was awarded only to Hahn who downplayed Meitner’s involvement. This was later described in Physics Today as “a rare instance in which personal negative opinions apparently led to the exclusion of a deserving scientist”.

Mary Anning – paleontology

Mary Anning. Grey/Royal Geological Society

Mary Anning (1799-1847) was a self-educated palaeontologist from a poor background in Lyme Regis in the southwest of England. Her discoveries of the first complete Ichthyosaur in 1811 and a complete Plesiosaurus in 1823 established her as an expert in fossils and geology, which she played a key role in establishing as a new scientific discipline.

Her expertise was much sought-after by educated male contemporaries even though, as a woman, she was ineligible to join the Geological Society of London. However, by the time of her death from breast cancer aged 47, Anning had gained the respect of scientists and the general public for her work.

Gertrude Elion – pharmacology

Gertrude Elion. Wellcome Foundation Archives, CC BY

Gertrude Elion (1918-1999) graduated from Hunter College in New York in 1937 with a degree in chemistry. Unable to complete a postgraduate degree due to the Great Depression, undeterred she spent time working as a lab assistant (for US$20 a week) and as a teacher until she obtained an assistant position at the Burroughs-Wellcome company.

Here she developed Purinethol, the first treatment for leukaemia, anti-malarial drug Pyrimethamine, and acyclovir, a treatment for viral herpes still sold today as Zovirax. Later Elion oversaw the adaptation of Azidothymidine, the first treatment for AIDS. In recognition of her achievements she was presented with the Nobel Prize in Physiology or Medicine in 1988, despite having never completed her PhD.

Jocelyn Bell Burnell – astrophysicist

Dame Jocelyn Bell Burnell. BBC

With a PhD in astrophysics from Cambridge University, Jocelyn Bell (1943-) built and worked on a radio telescope during her graduate studies. Here she discovered a repeating radio signal which, though it was initially dismissed by her colleagues, she traced to a rotating neutron star, later called a pulsar. For Jocelyn’s discovery of radio pulsars, described as “the greatest astronomical discovery of the 20th century”, her supervisor and his colleague were awarded the 1974 Nobel Prize in Physics.

Burnell was completely omitted as a co-recipient, to the outrage of many prominent astronomers at the time. However Burnell has gone on to receive many subsequent awards and honours, was President of the Royal Astronomical Society and the first women president of the Institute of Physics, and was appointed Dame Commander (DBE) of the Order of the British Empire in 2007.

Inspiration

My decision to study chemistry was inspired by my love for understanding the world around me and using science to help people. Learning about these incredibly tenacious women has kept me driven through tough weeks of thesis writing; the hardships they faced in their careers were immense in comparison to today.

Not only this, but it has reminded me of the amazing women colleagues around whom I am privileged to carry out my research. I spend time with scientists of many disciplines, all of whom inspire me daily. And while we women might happen to be fewer in number as scientists this has no bearing on our capacity to conduct intuitive, ground-breaking science now and for the future.