Nanako Hama gets a lot of mail, mostly from strangers who live in her home city of Tokyo. In light envelopes, they send locks of their hair, hoping to recycle it.

People generate a huge amount of hair waste. Nearly all of that waste ends up in landfill, where it can release harmful greenhouse gases that contribute to climate change.

But hair possesses useful qualities and it’s a shame to simply throw it away. That’s why people all around the world, like Hama, have been collecting hair and finding innovative ways to recycle it, including making mats (垫子) out of it for removing oil leaks,

Hama is part of the nonprofit Matter of Trust (MoT) members working at more than 60 centers dotted across 17 countries, using machines to make hair donated from local salons and individuals into square mats, which are then used to clean up the floating oil.

“Hair is particularly well-suited for this,” says MoT co-founder Lisa Gautier, “That’s because its rough sort of outer layer lets oil stick to it.” MoT’s mats have been used in major oil leaks, including the 2010 Deepwater Horizon and 2007 Cosco Busan incidents.

In a 2018 study, Murray, an environmental scientist at the University of Technology Sydney, in Australia found that mats made of recycled human hair could absorb 0.84 grams of oil onto its surface for every gram of hair — significantly more than polypropylene (聚丙烯), a type of plastic that’s typically used to clean up floating oil.

Besides, hair is also useful as fertilizer (化肥). Hair contains a relatively high nitrogen (氪), a chemical element crucial for plant growth, and each lock of hair is made of roughly 16 percent of this essential nutrient. Last year, more than 560 gallons of liquid fertilizer made from human hair was sold to farmers in northern Tanzania and the feedback from the farmers has been very encouraging.

“It’s just a great way to use hair in a productive way. Hair is an answer literally hanging in front of our eyes-for oil and soil, ” Hama says.

German physicist Albert Einstein is one of the most famous scientists of all time, the personification of genius and the subject of a whole industry of scholarship. In The Einsteinian Revolution, two experts on Einstein’s life and his theory of relativity — Israeli physicist Hanoch Gutfreund and German historian of science Jürgen Renn — offer an original and penetrating (犀利的) analysis of Einstein’s revolutionary contributions to physics and our view of the physical world.

By setting Einstein’s work in the long course of the evolution of scientific knowledge, Gutfreund and Renn discover the popular myth (谬论) of Einstein as an unconventional scientific genius who single-handedly created modern physics-and by pure thought alone.

As a large part of the book explains, Einstein typically argued that science progresses through steady evolution, not through revolutionary breaks with the past. He saw his theory of relativity not as something from scratch, but a natural extension of the classical physics developed by pioneers such as Italian astronomer Galileo Galilei and English physicist Isaac Newton in the sixteenth and seventeenth centuries, as well as nineteenth-century physicists.

The authors highlight how classical physics cannot be separated cleanly from modern Einsteinian physics. The book also includes substantial sections on Polish astronomer Nicolaus Copernicus and Galileo whose methods inspired Einstein. When Einstein considered himself as standing on their shoulders, he meant that, without their contributions, he would not have formulated (阐述) the theory of relativity.

The Einsteinian Revolution is an important and thought-provoking (引人深思的) contribution to the scholarly literature on Einstein and his surprising scientific creativity between 1905 and 1925. Gutfreund and Renn might not have given the final answer as to why Einstein, of all people, revolutionized physics in the way that he did. But they argue in fascinating detail that, to understand his genius, one must take into account not just the earlier history of physics but also the history of knowledge more broadly. Although not always an easy read, the book will interest physicists and historians alike.