Physics

New scale for electronegativity rewrites the chemistry textbook

Electronegativity is one of the most well-known models for explaining why chemical reactions occur. Now scientists have redefined the concept with a new, more comprehensive scale.

Zirconium isotope a master at neutron capture

The probability that a nucleus will absorb a neutron is important to many areas of nuclear science, including the production of elements in the cosmos, reactor performance, nuclear medicine and defense applications.

Molecules 'spin flip' from magnetic to non-magnetic forms dynamically

Solar cells, quantum computing and photodynamic cancer therapy. These all involve molecules switching between magnetic and nonmagnetic forms. Previously this process, called a "spin flip," was thought to occur slowly in most cases. Now, researchers have discovered spin flips happen in one half of one trillionth of a second, or half a picosecond in the course of a chemical reaction. To understand how fast it is -- watches count in seconds, sporting games are timed in 10ths of a second, and light travels just under 12 inches in one-billionth of a second. Spin flips are faster.

Scientists discover novel process to convert visible light into infrared light

Scientists have developed a novel chemical process to convert infrared energy into visible light, allowing innocuous radiation to penetrate living tissue and other materials without the damage caused by high-intensity light exposure. The discovery could advance numerous fields, including clinical applications for photodynamic therapy and drug development.

Fiery sighting: A new physics of eruptions that damage fusion experiments

Sudden bursts of heat that can damage the inner walls of tokamak fusion experiments are a hurdle that operators of the facilities must overcome. Such bursts, called 'edge localized modes (ELMs),' occur in doughnut-shaped tokamak devices that house the hot, charged plasma that is used to replicate on Earth the power that drives the sun and other stars. Now researchers have directly observed a possible and previously unknown process that can trigger damaging ELMs.

Simple rules predict and explain biological mutualism

Scientists have long employed relatively simple guidelines to help explain the physical world, from Newton's second law of motion to the laws of thermodynamics.

Ultra ultrasound to transform new tech

A new, more sensitive method to measure ultrasound may revolutionize everything from medical devices to unmanned vehicles. Researchers have combined modern nanofabrication and nanophotonics techniques to build the ultra precise ultrasound sensors on a silicon chip.

New quantum structures in super-chilled helium may mirror early days of universe

For the first time, researchers have documented the long-predicted occurrence of 'walls bound by strings' in superfluid helium-3. The existence of such an object, originally foreseen by cosmology theorists, may help explaining how the universe cooled down after the Big Bang. With the newfound ability to recreate these structures in the lab, earth-based scientists finally have a way to study some of the possible scenarios that might have taken place in the early universe more closely.

Experiments detect entropy production in mesoscopic quantum systems

The production of entropy, which means increasing the degree of disorder in a system, is an inexorable tendency in the macroscopic world owing to the second law of thermodynamics. This makes the processes described by classical physics irreversible and, by extension, imposes a direction on the flow of time. However, the tendency does not necessarily apply in the microscopic world, which is governed by quantum mechanics. The laws of quantum physics are reversible in time, so in the microscopic world, there is no preferential direction to the flow of phenomena.

Mechanism helps explain the ear's exquisite sensitivity

The human ear, like those of other mammals, is so extraordinarily sensitive that it can detect sound-wave-induced vibrations of the eardrum that move by less than the width of an atom. Now, researchers at MIT have discovered important new details of how the ear achieves this amazing ability to pick up faint sounds.

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