New light-powered catalysts could aid in manufacturing

Chemical reactions that are driven by light offer a powerful tool for chemists who are designing new ways to manufacture pharmaceuticals and other useful compounds. Harnessing this light energy requires photoredox catalysts, ...

Finding coherence in quantum chaos

A theoretical breakthrough in understanding quantum chaos could open new paths into researching quantum information and quantum computing, many-body physics, black holes, and the still-elusive quantum to classical transition.

New ultra-faint dwarf galaxy discovered

Astronomers from the University of Arizona (UA) and elsewhere report the discovery of a new ultra-faint dwarf galaxy. The newfound galaxy, designated Tucana B, is the first quenched and isolated object of this type identified ...

Chemists use light energy to produce small molecular rings

In the search for new active agents in medicine, molecules whose atoms are linked in rings are becoming increasingly important. Such ring systems have particularly suitable properties for producing such active agents and ...

How the universe got its magnetic field

When we look out into space, all of the astrophysical objects that we see are embedded in magnetic fields. This is true not only in the neighborhood of stars and planets, but also in the deep space between galaxies and galactic ...

Chemists' HAT trick for greener chemical synthesis

Creating new chemical compounds, such as new drugs, is not as simple as assembling one of those models with colored balls and sticks you might have seen in a beginning chemistry class. No, it's often a complex process with ...

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Energy

In physics, energy (from the Greek ἐνέργεια - energeia, "activity, operation", from ἐνεργός - energos, "active, working") is a scalar physical quantity that describes the amount of work that can be performed by a force, an attribute of objects and systems that is subject to a conservation law. Different forms of energy include kinetic, potential, thermal, gravitational, sound, light, elastic, and electromagnetic energy. The forms of energy are often named after a related force.

Any form of energy can be transformed into another form, but the total energy always remains the same. This principle, the conservation of energy, was first postulated in the early 19th century, and applies to any isolated system. According to Noether's theorem, the conservation of energy is a consequence of the fact that the laws of physics do not change over time.

Although the total energy of a system does not change with time, its value may depend on the frame of reference. For example, a seated passenger in a moving airplane has zero kinetic energy relative to the airplane, but non-zero kinetic energy relative to the Earth.

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