What is the Mpedmba effect?

Despite sounding like the most egregious contradiction in physics, hot water appears to freeze faster than cold water under certain circumstances. The phenomenon can be traced back to Aristotle himself, but after centuries of experiments demonstrating this phenomenon, no one’s been able to explain it. Now physicists are pointing to strange properties of hydrogen bonds as the solution to one of the oldest mysteries in physics – but others are claiming the so-called Mpemba effect doesn’t even exist at all.

“The analysis … leads us to propose a molecular explanation for the Mpemba effect. In warm water, the weaker H-bonds with predominantly electrostatic contributions are broken, and smaller water clusters with … strong H-bonding arrangements exist that accelerate the nucleation process that leads to the hexagonal lattice of solid ice.

Therefore, water freezes faster than cold water in which the transformation from a randomly-arranged water clusters costs time and energy.”

via The claim that hot water freezes faster than cold water just got even weirder – ScienceAlert.

Naughty Photons

Physicists have performed a variation of the famous 200-year-old double-slit experiment that, for the first time, involves “exotic looped trajectories” of photons. These photons travel forward through one slit, then loop around and travel back through another slit, and then sometimes loop around again and travel forward through a third slit.Interestingly, the contribution of these looped trajectories to the overall interference pattern leads to an apparent deviation from the usual form of the superposition principle. This apparent deviation can be understood as an incorrect application of the superposition principle—once the additional interference between looped and straight trajectories is accounted for, the superposition can be correctly applied.

via Physicists detect exotic looped trajectories of light in three-slit experiment.

CRISPR now has an off switch

A lot has been written about CRISPR over the past year.   Despite its potential, it’s still very new technology that, like any new technique, has the potential to cause side effects we can’t yet predict – which could be really bad if we start using it regularly in humans. The good news is that scientists think they might have found an ‘off-switch’ that stops CRISPR in its tracks.