Quanta Physics World  June 2021

Seen and heard

Weird and wonderful stories from the world of physics

(Courtesy: Yaroslava Andreeva)

The starry oxide night 

Vincent van Gogh’s 1889 masterpiece The Starry Night, which depicts the view just before sunrise from his asylum room in Saint-Rémy-de-Provence, has long been a hit with art lovers. But the painting is proving of great interest to scientists too. A few years ago researchers in Australia analysed the vividly coloured artwork, finding that it depicted realistic turbulence (April 2019). Not to be outdone, scientists in Russia have now created a 7 × 5 cm reproduction of the picture using just a laser and a metal surface. Vadim Veiko, Yaroslava Andreeva and colleagues at ITMO University in St Petersburg heated the surface of the metal to create oxide layers that could produce a palette of nine basic colours (Optica 8 557). The piece took just a few minutes to make and the team now hopes to incorporate the laser-painting technology into a handheld tool. 

Lager top 

If you pour 100 ml of champagne straight down the middle of a vertically oriented flute-shaped glass, you’ll nucleate about one million bubbles – and tens of thousands more if you tilt the vessel. Gérard Liger-Belair from the University of Reims Champagne-Ardenne, who reported his fun fact in Physics World (December 2015), has now turned his attention to beer. He and a colleague first measured the carbon dioxide content of a freshly poured glass of lager at 5 °C and then calculated how many bubbles would form at defects in the glass that are more than 1.4 μm wide. After a painstaking analysis, they concluded that between 200,000 and nearly two million bubbles are created in a gently poured glass of lager before it goes flat (ACS Omega 6 9672). Interestingly, they found that beer and champagne bubbles form differently in a glass, with larger imperfections leading to more bubbles in beer but not in champagne. We’ll raise a glass to that. 

It’s in the air 

After all that beer testing, you might need to go to the toilet, but whatever you do, don’t linger afterwards. That’s because researchers at Florida Atlantic University have analysed how aerosols with the potential to carry disease are created and dispersed by flushing toilets and urinals. Siddhartha Verma and colleagues studied three scenarios – toilet flushing, covered toilet flushing and urinal flushing – in a public facility on the Florida campus (Physics of Fluids 33 033320). After three hours of tests and more than 100 flushes, the team detected droplets smaller than 3 μm in size at a height of 1.5 m above a toilet or urinal (face height for many people) and found that the droplets persisted at that height for more than 20 seconds after the flush. Unfortunately, closing the toilet lid before flushing did not do much to cut the number of particles detected – suggesting that aerosol particles can easily escape through gaps around the seat and lid. Maybe it’ll still be worth wearing facemasks once the pandemic is over. 

 

(Courtesy: Canadian Space Agency/NASA)

Smart shirt 

In 2019 Canadian astronaut David Saint-Jacques tested out a “technology-packed tank top” during his stay on the International Space Station. Created by Montreal-based Carré Technologies, a firm that produces wearable sensors, the Bio-Monitor shirt allows astronauts to be monitored while performing a range of activities – without having to stop what they are doing at regular intervals to make measurements. The data collected from the mission have now been combed over by researchers at the Schlegel-University of Waterloo Research Institute for Aging, who found that the shirt was able to accurately measure heart rate, breathing rate, oxygen saturation in the blood, physical activity and skin temperature. The designers say that if astronauts continue to wear the shirt once home, it could provide early warning for problems re-adapting to gravity back on Earth. You can even get your hands on your very own vest – but the technology won’t come cheap at $499 for the “smart kit”. Perhaps not so smart after all.