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Large objects, including cats, don’t show quantum effects. But physicists aren’t sure where the size limit lies. Credit: Getty
In the iconic quantum double-slit experiment, a photon acts like a wave and interferes with itself — illustrating the mind-boggling concept that particles can exist in a ‘superposition’ of possible locations at once. But just how big can such a quantum object be? At least as big as a blob of around 7,000 sodium atoms, it turns out. Using a painstakingly constructed experimental set-up, researchers managed to observe tell-tale interference patterns for sodium clusters some 8 nanometres wide, with superpositions that stretched across 133 nanometres. The clusters are as big as some viruses, raising the tantalizing possibility of putting biological matter through the same experimental set-up.
Go deeper with physicist Tim Kovachy’s analysis in the Nature News & Views article (9 min read, Nature paywall)
Researchers have engineered magnetically controlled fluorescent proteins that can be remotely dimmed and brightened in bacterial cells and in animals. The dimming is due to an effect through which the quantum properties of an electron pair in the protein could be altered by a magnetic field. This effect allows researchers to manipulate the brightness of the protein in E. coli bacteria with a combination of magnets and radio waves. The hope is that these proteins’ magnetic sensitivity can be exploited to develop remote-controlled biosensors, or even therapies that can be turned on and off when needed.
The outline of a hand discovered in an Indonesian cave has been dated to at least 67,800 years ago — the oldest known example of cave art in the world. The researchers who discovered the painting suggest that it was made using a stencil that was altered to give the shape a claw-like appearance. The finding provides circumstantial backing for a controversial theory that early humans had arrived in Sahul — the landmass that once encompassed modern-day Australia and New Guinea — by 65,000 years ago, around 15,000 years earlier than previously thought.
The outline of a hand — stencilled in faded orange pigment and faintly visible behind another, darker brown shape — could hold clues to patterns of early human migration in south-east Asia and Australasia. (Max Aubert)
Features & opinion
Around the world, girls are starting puberty younger than they once did — a trend that some research hints mysteriously accelerated during the COVID-19 pandemic. Increasing body weight has almost certainly played a part in this change, researchers say, and exposure to hormone-disrupting chemicals or stress could also be implicated. An earlier puberty has been linked to higher risks of conditions including heart disease and breast cancer. Clinicians are trying to work out how and whether to intervene, be that medically or through support to mitigate the social and psychological risks.
Hardwick Hall, a stately home in the United Kingdom, was constructed in the 1590s during a prolonged period of cold known as the ‘Little Ice Age’. The mansion was intentionally erected on a north–south axis, with windows strategically placed to make the most of sunlight and fireplaces only on internal walls — measures that kept the inside of the house relatively balmy. This temperature-conscious design could offer modern architects tips on how to construct buildings that better regulate their internal temperatures without relying on air conditioning or central heating, historians say.
Teenagers with attention deficit hyperactivity disorder (ADHD) are particularly prone to long hours of compulsive scrolling on social media, the result of differences in how their brains regulate attention and reward. They are also disproportionately likely to use social media in dangerous ways such as sharing personal information and engaging in risky interactions. But researchers can’t say definitively whether social media fuels ADHD or simply feeds on it.
This article is part of Nature Outlook: ADHD, an editorially independent supplement produced with financial support from Otsuka America Pharmaceutical, Inc.
Infographic of the week
Fossils of one of the oldest known vertebrate species (Haikouichthys ercaicunensis) suggest that the fish had four eyes — two on the top of its head and one on each side. Evidence from the 518-million-year-old specimens suggests that the two smaller eyes had lenses and an organized arrangement of the pigment melanin, which would give them the capacity to make images. In gnathostomes, modern vertebrates with jaws, the light-sensing organs at the top of the head have evolved into various types of an organ called a pineal complex, which can’t generate images. (Nature News & Views | 5 min read)
Today I’m jamming along to the dulcet tones of a new instrument: the Post-Digital Sax. The ‘cyborg’ instrument combines the best of both worlds — it’s played through an acoustic horn, with an electronic component allowing for digital pitch control.
The sax is a finalist in the 28th Guthman Musical Instrument Competition, an annual contest to find the best new technologies in music. The winner will be decided at the end of a weekend-long showcase of all 10 finalists in March.
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