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  2. Zero-energy universe - Wikipedia

    en.wikipedia.org/wiki/Zero-energy_universe

    Some physicists, such as Lawrence Krauss, Stephen Hawking or Alexander Vilenkin, call or called this state "a universe from nothingness", although the zero-energy universe model requires both a matter field with positive energy and a gravitational field with negative energy to exist. [2] The hypothesis is broadly discussed in popular sources.

  3. Uncertainty principle - Wikipedia

    en.wikipedia.org/wiki/Uncertainty_principle

    where = is the reduced Planck constant.. The quintessentially quantum mechanical uncertainty principle comes in many forms other than position–momentum. The energy–time relationship is widely used to relate quantum state lifetime to measured energy widths but its formal derivation is fraught with confusing issues about the nature of time.

  4. Black hole information paradox - Wikipedia

    en.wikipedia.org/wiki/Black_hole_information_paradox

    The loss of information can be quantified in terms of the change in the fine-grained von Neumann entropy of the state. A pure state is assigned a von Neumann entropy of 0, whereas a mixed state has a finite entropy. The unitary evolution of a state according to Schrödinger's equation preserves the entropy. Therefore Hawking's argument suggests ...

  5. Eternal oblivion - Wikipedia

    en.wikipedia.org/wiki/Eternal_oblivion

    Eternal oblivion (also referred to as non-existence or nothingness) [1] [2] is the philosophical, religious, or scientific concept of one's consciousness forever ceasing upon death. Pamela Health and Jon Klimo write that this concept is mostly associated with religious skepticism , secular humanism , nihilism , agnosticism , and atheism . [ 3 ]

  6. Entropy - Wikipedia

    en.wikipedia.org/wiki/Entropy

    For an open thermodynamic system in which heat and work are transferred by paths separate from the paths for transfer of matter, using this generic balance equation, with respect to the rate of change with time of the extensive quantity entropy , the entropy balance equation is: [53] [54] [note 1] = = ˙ ^ + ˙ + ˙ where = ˙ ^ is the net rate ...

  7. Free-space path loss - Wikipedia

    en.wikipedia.org/wiki/Free-space_path_loss

    In telecommunications, the free-space path loss (FSPL) (also known as free-space loss, FSL) is the attenuation of radio energy between the feedpoints of two antennas that results from the combination of the receiving antenna's capture area plus the obstacle-free, line-of-sight (LoS) path through free space (usually air). [1]

  8. Schrödinger equation - Wikipedia

    en.wikipedia.org/wiki/Schrödinger_equation

    The Klein–Gordon equation, + =, was the first such equation to be obtained, even before the nonrelativistic one-particle Schrödinger equation, and applies to massive spinless particles. Historically, Dirac obtained the Dirac equation by seeking a differential equation that would be first-order in both time and space, a desirable property for ...

  9. Entropy in thermodynamics and information theory - Wikipedia

    en.wikipedia.org/wiki/Entropy_in_thermodynamics...

    Or, in the words of G. N. Lewis writing about chemical entropy in 1930, "Gain in entropy always means loss of information, and nothing more". To be more concrete, in the discrete case using base two logarithms, the reduced Gibbs entropy is equal to the average of the minimum number of yes–no questions needed to be answered in order to fully ...