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  2. Negative mass - Wikipedia

    en.wikipedia.org/wiki/Negative_mass

    In theoretical physics, negative mass is a hypothetical type of exotic matter whose mass is of opposite sign to the mass of normal matter, e.g. −1 kg. [1] [2] Such matter would violate one or more energy conditions and exhibit strange properties such as the oppositely oriented acceleration for an applied force orientation.

  3. Exotic matter - Wikipedia

    en.wikipedia.org/wiki/Exotic_matter

    Negative mass would possess some strange properties, such as accelerating in the direction opposite of applied force. Despite being inconsistent with the expected behavior of "normal" matter, negative mass is mathematically consistent and introduces no violation of conservation of momentum or energy .

  4. Negative energy - Wikipedia

    en.wikipedia.org/wiki/Negative_energy

    The negative-energy particle then crosses the event horizon into the black hole, with the law of conservation of energy requiring that an equal amount of positive energy should escape. In the Penrose process , a body divides in two, with one half gaining negative energy and falling in, while the other half gains an equal amount of positive ...

  5. Zero-energy universe - Wikipedia

    en.wikipedia.org/wiki/Zero-energy_universe

    Gravitational energy from visible matter accounts for 26–37% of the observed total massenergy density. [15] Therefore, to fit the concept of a "zero-energy universe" to the observed universe, other negative energy reservoirs besides gravity from baryonic matter are necessary. These reservoirs are frequently assumed to be dark matter. [16]

  6. Hawking radiation - Wikipedia

    en.wikipedia.org/wiki/Hawking_radiation

    Hawking radiation would reduce the mass and rotational energy of black holes and consequently cause black hole evaporation. Because of this, black holes that do not gain mass through other means are expected to shrink and ultimately vanish. For all except the smallest black holes, this happens extremely slowly.

  7. Energy condition - Wikipedia

    en.wikipedia.org/wiki/Energy_condition

    For example, in the words of W. Israel: “If the source of an effect can be delayed, it should be possible for a system to borrow energy from its ground state, and this implies instability”. [6] It is possible to show that this is a restatement of the Hawking-Ellis vacuum conservation theorem at finite temperature and chemical potential. [4] [5]

  8. Second law of thermodynamics - Wikipedia

    en.wikipedia.org/wiki/Second_law_of_thermodynamics

    For a similar process at constant temperature and volume, the change in Helmholtz free energy must be negative, <. Thus, a negative value of the change in free energy (G or A) is a necessary condition for a process to be spontaneous. This is the most useful form of the second law of thermodynamics in chemistry, where free-energy changes can be ...

  9. Mass–energy equivalence - Wikipedia

    en.wikipedia.org/wiki/Massenergy_equivalence

    Massenergy equivalence states that all objects having mass, or massive objects, have a corresponding intrinsic energy, even when they are stationary.In the rest frame of an object, where by definition it is motionless and so has no momentum, the mass and energy are equal or they differ only by a constant factor, the speed of light squared (c 2).