Now you see me: true invisibility cloak impossible to build

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Strike the invisibility cloak off your wish list. They are impossible to build for human-sized objects, says a new study.

Invisibility cloaks have been a goal for about 10 years, since John Pendry and colleagues at Imperial College London proposed a way to guide light over or around an object using substances with exotic optical properties, called metamaterials.

Read the full story in New Scientist.

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Why Preprints in Physics, But Not Biology? – Undark

Scientific journal policies, along with differences in the history and culture of the disciplines, may play a role.

In a piece published in the New York Times last month, Amy Harmon wrote about “rogue” biologists publishing their research directly to the Web. But as Harmon noted, this kind of activity is hardly news for physicists, who have been publishing these so-called “preprints” — that is, research published digitally, prior to appearing in a formal, peer-reviewed journal — on the website arXiv.org since 1991.

Read the full story in Undark.

Local supernova 2 million years ago solves cosmic ray puzzle

Image credit: NASA/CXC/SAO/Science Photo Library

All signs point to a supernova. A stellar explosion 2 million years ago that flooded our neighbourhood with charged particles could be the answer to several cosmic puzzles.

For years, astrophysicists have struggled to explain why there are so many high-energy cosmic rays – speeding charged particles that hit Earth from all directions.

Read the full article in New Scientist.