【推荐1】Although Sir Isaac Newton did not employ his reflecting telescope to uncover novel astronomical phenomena, he did use it to completely transform how we view the world we live in and the universe as a whole.

Reflecting telescopes use mirrors to bend light and enlarge images, distinguishing them from refractors (折射望远镜) that rely on lenses. Their simplicity in construction and ability to achieve much greater sizes than refractors have led to a transformation in our astronomical knowledge and our comprehension of the universe.

As light passes through glass, various colors or bands are refracted at varying angles, leading to chromatic aberration (色差) and consequently, distorted images when viewed through a lens. In the time of Newton, the technology for producing glass and lenses was still very primitive, and the challenges associated with chromatic aberration had not been adequately addressed. Today we can make lenses that have almost no chromatic aberration but we can’t make them very large. As the size of a lens increases significantly, it becomes extremely heavy, causing its own weight to distort the lens and consequently ruin the image quality.

Newton’s telescope solved these problems. A mirror doesn’t allow light to pass. It simply bounces all the light off the surface. This means there’s no chromatic aberration. Plus, because we only need to bounce light off the surface, we can support the entire mirror on a base, reducing its weight. This allows us to build much larger mirrors without any distortion.

While Galileo is credited with the discovery of moons around Jupiter and Halley with predicting the comet’s orbit, what Newton did do was tie in mathematics, astronomy and our comprehension of the universe through the use of his telescope and his universal gravitation theory.

The original telescope constructed by Newton is preserved and maintained by the Royal Society of London. It is showcased in London and occasionally embarks on international tours as an element of exhibitions.

【推荐1】Imagine your smartphone’s screen gets broken, or your favourite boots get a hole in them. What do you do? You could buy a replacement. Or you could join the worldwide trend of taking your broken stuff to a “repair café”.

The Bower Reuse and Repair Centre has just launched Australia’s first repair café, in Sydney’s inner west. The crowd-funded project will hold weekly repair sessions focusing on bikes, furniture and electrical items.

The first repair café was set up in Amsterdam in 2009, and the Repair Cafe Foundation says there are now more than 400 around the world. A repair café is a free face-to-face meeting of skilled volunteers and local residents who want things fixed. Visitors bring broken items from home and watch, learn or help as the repairs get done. Some things are fixed during the event, while for more challenging items people might be referred to local speciality repair shops.

Last year, according to the ABS, Australians sent more than half a million tons of leather to landfill—more than ten times the amount that was reused or recycled. Mending represents an attempt to resist the throwaway culture. Repair cafés get people talking and give them the chance to network and learn about the local resources available. And, perhaps most surprisingly for anyone who considers mending to be some kind of drudgery, repair cafés can be fun and creative.

“In a circular economy, repair cafés fit right in”, says the organiser Martine Postma. In rejecting buy-use-throw, the circular economy aims to keep resources moving around in the economy, rather than moving them through it to a dead end, where they cannot be put into valuable use.

It might be quicker and easier to throw stuff in the bin, but it’s more expensive and less fun too.

【推荐3】From Smells to Soundtracks

When a young sawfly, a bee-like insect, is threatened by its attackers like ants, it emits a mixture of unpleasant smells to defend itself. These emissions can seriously annoy a potential enemy.

Scientists wanting to study these smelly compounds—to understand which aspects of them discourage attackers and why—face great challenges. Meetups between sawflies and ants in a lab are difficult to carry out. There are also a very limited quantity of the insects’ emissions. On the side, Jean-Luc Boevé, a zoologist who studies insects, from the Royal Belgian Institute of Natural Sciences, is an amateur musician and composer. He decided to try a different way—the sound approach. “To be honest, I considered this project so unpractical myself that I set it aside,” he said. It was months before Boevé and his partner, Rudi Giot, finally made a resolution to get started on it.

They chose 16 sawfly species’ emissions to translate into sounds. First, they figured out which molecules (分子) were present in each smelly compound and in what amounts. Then they assigned various characteristics of those molecules matching properties of sound. For example, smaller molecules like a kind of acid found in vinegar, a sour-tasting liquid, evaporate (挥发) quickly, so Boevé and Giot assigned them sounds with higher pitch ( 音 高 ). Larger molecules were given lower-pitched sounds. In all, the scientists created individual audio descriptions for 20 molecules. Then they combined the sounds of each molecule present in a sawfly’s smell to construct the insect’s soundtrack. If a molecule was of higher proportion in an emission, they assigned it a higher volume. In such a case, the smaller a molecule is, the higher its pitch will be; and the higher the proportion of a molecule is, the higher its volume will be.

To test out the audio descriptions they created, Boevé and Giot examined people’s reactions to the soundtracks and compared them to ants’ reactions to the original smells. They played the 16 emission soundtracks and the 20 molecule sounds through speakers to about 50 study participants. Then the scientists measured how far people backed up to get to a “comfortable position” away from the noise. Most of the study volunteers told the researchers that the high pitch, as well as the high volume, was what made them withdraw. “Ants and volunteers moved away from a chemical and its matching soundtrack respectively,” the researchers wrote.

Boevé said he hoped the process would give other zoologists a new way to compare sawflies’ chemical defenses with those from other insects. It may also offer researchers clues about which molecules fight off enemies most.