Physics

Ask a physicist how a particle gets from here to there and the answer can sound like a joke at the expense of common sense: it goes every way it possibly can. Straight across, out to the side and…

A femtosecond is a millionth of a billionth of a second, and for chemistry it is the natural unit: atoms in a molecule take tens or hundreds of femtoseconds to rearrange. Electrons are quicker. They…

Nobody has ever put a thermometer 5,000 kilometers down. The temperature at Earth's center is inferred, not measured, and one of the load-bearing numbers behind that inference is the melting point of…

Energy inside molecules does not simply teleport from one place to the next. It has to be carried, and some kinds of energy are far harder to carry than others. The stubborn case is the "triplet," a…

Stretch a rubber band and it eventually snaps. Pour honey and it just keeps flowing, however hard you pull. That contrast is one of the first things anyone learns about matter: solids can fracture,…

Nothing in the apparatus actually spins. That is the first surprise, and the one that makes the rest of the story hang together. Sitting on a bench at the City University of New York's Advanced…

For a few millionths of a second after the Big Bang, the universe was too hot for ordinary matter to exist. Protons and neutrons had not formed; instead, their constituents, quarks and gluons,…

Every clock is, at heart, a thing that ticks at a rate you can count on. A pendulum swings; a quartz crystal vibrates; in the best atomic clocks, electrons jump between two energy levels exactly so…

In quantum technology, sometimes the most valuable thing in a material is a flaw. The most famous example lives in diamond, where a missing carbon atom paired with a nitrogen atom creates a defect…

For years, the perovskite polariton laser has had an awkward secret: to make it shine, you had to shine another laser at it. That is not a small caveat. A laser you can only switch on with a second,…

Picture an ant trying to walk a trail while a herd of elephants stampedes down the same path. That is roughly the problem Prem Kumar and his group at Northwestern set themselves, and the ant,…

The whole trick of super-resolution microscopy is a kind of accounting. You cannot see a fluorescent molecule; you can only see the smeared blob of light it throws onto a camera, and that blob is…