energy transfer

A courier carrying a package enters a dense forest of intertwined ropes. He needs to deliver the cargo deep inside, but along the way he loses strength, and each step becomes harder. This is what an enzyme looks like as it degrades a dense gel of biological molecules. Until recently, no one could simultaneously see how the courier moves and how the forest thins out.

A regular battery releases heat smoothly: what you store is what you get. The power is fixed once and for all, like a faucet that pours water in a single stream. But sometimes you don't need a steady flow; you need a short, powerful burst: to instantly heat a part, trigger a reaction, or dump excess heat.

Light hits a solar cell, and inside, charges are born, hot and bothered. Like a person after a jog, they carry extra energy. To deliver current to an external circuit, they need to cool down and reach the edges of the crystal. If cooling drags on, part of the energy is wasted. Perovskite is a mineral that scientists have learned to make artificially.

A sponge slowly watered from a watering can gets soaked all the way through. But if you dump the same bucket of water on it all at once, the middle gets wet while the edges stay almost dry. That's roughly how a material with nonlinear absorption behaves: the more intense the flux, the more it gets stuck at the point of impact.

The lifetime of the entangled triplet pair in the protein is about 60 picoseconds, which is eight times longer than in solution. Sunlight is like a continuous stream of balls flying at a wall.

In a crystal, heat travels on waves. Atoms vibrate, and these vibrations, called phonons, carry energy from the hot edge to the cold one. For a long time, it was believed that if phonons hit resonance (their frequencies exactly match) and can exchange energy, heat would flow like an avalanche. It turns out that's not the case.

Crystals glued to the outside and inside of a metal wall act as an invisible channel. One, receiving current, starts to tremble, and these vibrations, like ripples on water, spread out in all directions through the metal. The inner crystal catches this tremor and generates electricity again.

A colony of cells resembles a squad blazing a trail through unknown terrain. In living tissue, this role is often played by chemotaxis — movement along a gradient of a chemical that the cells themselves secrete. Earlier models described homogeneous groups, but in reality, different cell types interact.

A surfer glides across the ocean surface until a big wave comes, and then they're flying forward. Similarly, a free electron interacts with light: usually the energy exchange is barely noticeable, but if the surrounding medium begins to oscillate rhythmically, each wave crest pushes the particle harder and harder.

Two guitar strings are stretched on the same neck. They are almost identical, but one is slightly shorter — and they sound different. That's roughly how the two isomers of ethanimine work: molecules with the same set of atoms but rotated differently in space. Astronomers spotted this molecule in the dense clouds near the center of our Galaxy.

Sunlight hits a material, and each photon knocks out one electron. That's the usual order of things, which is why ordinary solar cells can't convert more than a third of the energy into electricity — the rest is lost as heat. But there's a process akin to a billiard shot where one ball splits into two: carrier multiplication.

In December 2011, Comet Lovejoy boldly raced through the searing corona of the Sun. Right after — a flare. Scientists checked whether the comet could have caused it. The atmosphere of the Sun is threaded with taut magnetic loops, like a drawn bowstring.

A swing only gets going if you push it in rhythm. Miss the beat, and your effort is wasted. Light interacts with an atomic nucleus in much the same way: a photon is usually absorbed only when its energy exactly matches the gap between nuclear levels. But what if the photon's energy doesn't fit? The authors of a new study have found a workaround.

An ordinary envelope has a rectangular shape, and the letter inside does not change the envelope's properties. With photons, particles of light, the situation is different: their 'shape' in time can vary, and this shape itself carries information.

Prostate cancer radiation therapy requires precise calculation of the radiation dose at every point in the body. The classic Monte Carlo method simulates millions of particles and takes hours, while adapting the plan to daily anatomical changes needs seconds.

A solar cell usually catches light with one side, and at the back it has a solid metal substrate. Here, the back wall was made from a transparent conducting material — indium tin oxide. Light that the cell doesn't absorb passes through.

In a molecule resembling chlorophyll and built from carbon, a metal atom at the center acts as a toggle. Shifting it by fractions of a nanometer can make the molecule glow, quench, or boost its brightness a hundredfold.

Tumors grow fast, and oxygen inside them often runs short. Conventional drugs that need oxygen are powerless there. But some molecules work differently: they pull electrons from neighboring molecules and trigger a chain reaction that destroys cancer cells. Such molecules are called photosensitizers: they are activated by light.

A solar panel is like a layered cake: a silicon base with thin metal strips on top that carry electricity to the wires. For a long time, these strips were made of silver: it conducts current excellently and doesn't harm silicon. But silver is pricey, so engineers are looking for alternatives.

The tiny green alga Chlamydomonas spends its life rowing with two flagella toward light, like a swimmer heading for shore. It senses light with a photoreceptor protein, and behind it lies a red spot — the 'eyespot'—which casts a shadow and helps the cell figure out where the light is coming from.

A glowing dot the size of a molecule. Run a current through it, and it flashes like a tiny lightbulb. That's what the experiment with dye molecules on a thin salt film looks like. When current enters a molecule, one electron hands it energy. The molecule immediately gives that energy back, as light. It's like a swing: give it one push, and it rocks and then stills.

When a sunbeam hits a leaf, a relay race begins inside it. The energy of light passes from one chlorophyll molecule to the next until it reaches the reaction center — the place where the chemistry of life kicks off. This relay runs with astonishing accuracy: nearly every quantum of light finds its way.

An ordinary solar cell does one thing: when the sun shines, current flows. Here, when the sun shines, the current flows differently depending on which side you bring the magnet.

Light in semiconductors is born from pairs of charges, an electron and a hole, that attract each other like a magnet to a fridge. Such a pair is called an exciton. If you add one more charge to the pair, you get a trion — a trio of three particles.

On March 30, 2022, two spacecraft — BepiColombo and STEREO-A — simultaneously felt a shockwave from the Sun. The first was at 0.6 times the Earth-Sun distance, the second at exactly one such distance.

After an injection under the skin, a drug doesn't just spread out like ink in water. Antibody molecules carry an electric charge, and that charge makes them interact with surrounding tissues — much like a magnet attracts or repels iron filings.

Plants employ an army of perfect couriers to deliver energy. Each photon of sunlight is absorbed, and its energy is instantly, with almost no loss, transferred to reaction centers where nutrient synthesis occurs.

A postal money order doesn't arrive instantly but after a set delay, and the amount credited to the recipient's account ends up larger than what the sender deposited in cash. That's roughly how the new protocol, dubbed temporal quantum energy teleportation (TQET), works. In ordinary quantum energy teleportation, two parties, Alice and Bob, share a common quantum state.