Sonic booms in nerves and lipid membranes

(Phys.org)—Neurons might not be able to send signals as fast as electrons in wires or photons in fiber, but what if they can communicate using miniature sonic booms? That would be quite a revolutionary discovery. A group ...

Physicist proves impossibility of quantum time crystals

(Phys.org) —Is it possible that a moving object could have zero energy? The common sense answer is no, since motion itself is kinetic energy, but this answer has been challenged recently by the concept of quantum time crystals. ...

Tunable quantum cascade laser

(PhysOrg.com) -- One of the issues associated with lasers is their tunability. In many cases, if you want to produce a particular wavelength, you have to build a laser to accomplish this. In order to get another wavelength, ...

Could Maxwell's Demon Exist in Nanoscale Systems?

(PhysOrg.com) -- Maxwell’s demon may be making a comeback. Physicists know that the demon, an imaginary creature that decreases the entropy of a system, cannot exist in macroscopic systems due to the energy it requires ...

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Energy level

A quantum mechanical system or particle that is bound, confined spatially, can only take on certain discrete values of energy, as opposed to classical particles, which can have any energy. These values are called energy levels. The term is most commonly used for the energy levels of electrons in atoms or molecules, which are bound by the electric field of the nucleus. The energy spectrum of a system with energy levels is said to be quantized.

If the potential energy is set to zero at infinity, the usual convention, then bound electron states have negative potential energy.

Energy levels are said to be degenerate, if the same energy level is obtained by more than one quantum mechanical state. They are then called degenerate energy levels.

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