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Ask Ethan: Could You Have Two Perfectly Identical Snowflakes?

Forbes - Tech

According to the Guinness book of world records, Nancy Knight, a scientist at the National Center for Atmosphere Research, serendipitously discovered two identical examples of snowflakes while studying snow crystals from a storm in Wisconsin in 1988, using a microscope. But when Guinness certifies two snowflakes as identical, they can only mean that it's identical to the precision of the microscope; when physics demands that two things be identical, they mean identical down to the subatomic particle!


Physicists Are Closer to Knowing the Size of a Proton … Sort of

WIRED

How big is a proton? That might sound like a pretty simple question, but it turned out to have the potential to wreck a lot of modern physics. That's because different methods of measuring the proton's charge radius produced results that disagreed--and not just by a little bit. The answers were four standard deviations apart. But now, a new and improved measurement brings them into much closer alignment--though not quite close enough that we can consider the issue resolved. This story originally appeared on Ars Technica, a trusted source for technology news, tech policy analysis, reviews, and more.


A molecular mediator for reductive concerted proton-electron transfers via electrocatalysis

Science

Many chemical reactions involve concurrent transfer of a proton and an electron. In electrochemical synthesis, this mechanism could prove useful in lowering the energy necessary for cathodic electron transfer alone, but it is hindered by competing direct coupling of the protons and electrons to make hydrogen instead. Chalkley et al. now report a molecular mediator consisting of a dimethylaniline base tethered to a cobaltocenium electron acceptor. This construct can deliver both a proton and an electron to a substrate from an acid and a cathode while skirting the hydrogen pathway. Science , this issue p. [850][1] Electrocatalytic approaches to the activation of unsaturated substrates via reductive concerted proton-electron transfer (CPET) must overcome competing, often kinetically dominant hydrogen evolution. We introduce the design of a molecular mediator for electrochemically triggered reductive CPET through the synthetic integration of a Brønsted acid and a redox mediator. Cathodic reduction at the cobaltocenium redox mediator substantially weakens the homolytic nitrogen-hydrogen bond strength of a Brønsted acidic anilinium tethered to one of the cyclopentadienyl rings. The electrochemically generated molecular mediator is demonstrated to transform a model substrate, acetophenone, to its corresponding neutral α-radical via a rate-determining CPET. [1]: /lookup/doi/10.1126/science.abc1607


Physics Has Demoted Mass - Issue 54: The Unspoken

Nautilus

Whatever it is, we call it matter or material substance. It has a characteristic property that we call solidity. But what is matter, exactly? Imagine a cube of ice, measuring a little over one inch (or 2.7 centimeters) in length. Imagine holding this cube of ice in the palm of your hand. It is cold, and a little slippery. It weighs hardly anything at all, yet we know it weighs something.


Would You Notice If An Atom Of Anti-Hydrogen Annihilated In Your Room?

Forbes - Tech

If an atom of anti-hydrogen came into existence in the room you are in, would you notice? One of the first lead-lead collisions at the Large Hadron Collider, recorded by the ALICE detector in November 2010. In this collision of lead nuclei at a small impact parameter (central collision), 1209 positively-charged (darker tracks) and 1197 negatively-charged (lighter tracks) particles are produced. Anti-hydrogen is the antimatter equivalent of the hydrogen atom. The simplest atom in our Universe, hydrogen is usually made of a single proton and a single electron.