G20 set to agree on marine plastic pollution deal

The Group of 20 major economies were set to agree a deal on reducing marine plastic waste at a meeting in Japan Sunday where they also discussed energy security following the oil tanker attacks in the Gulf of Oman.

Heat wave hits Iraq—and sparks begin to fly

Hospital ventilators shut down, football matches with obligatory water breaks and food spoiling in fridges without power: Iraq's notorious summer has arrived.

Carbon-neutral fuel made from sunlight and air

Researchers from ETH Zurich have developed a novel technology that produces liquid hydrocarbon fuels exclusively from sunlight and air. For the first time worldwide they demonstrate the entire thermochemical process chain ...

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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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