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  2. Space hierarchy theorem - Wikipedia

    en.wikipedia.org/wiki/Space_hierarchy_theorem

    The hierarchy theorems are used to demonstrate that the time and space complexity classes form a hierarchy where classes with tighter bounds contain fewer languages than those with more relaxed bounds. Here we define and prove the space hierarchy theorem. The space hierarchy theorems rely on the concept of space-constructible functions.

  3. Quantum mechanics of time travel - Wikipedia

    en.wikipedia.org/wiki/Quantum_mechanics_of_time...

    The theoretical study of time travel generally follows the laws of general relativity. Quantum mechanics requires physicists to solve equations describing how probabilities behave along closed timelike curves (CTCs), which are theoretical loops in spacetime that might make it possible to travel through time. [1] [2] [3] [4]

  4. Time hierarchy theorem - Wikipedia

    en.wikipedia.org/wiki/Time_hierarchy_theorem

    However, the time hierarchy theorems provide no means to relate deterministic and non-deterministic complexity, or time and space complexity, so they cast no light on the great unsolved questions of computational complexity theory: whether P and NP, NP and PSPACE, PSPACE and EXPTIME, or EXPTIME and NEXPTIME are equal or not.

  5. Spacetime - Wikipedia

    en.wikipedia.org/wiki/Spacetime

    In physics, spacetime, also called the space-time continuum, is a mathematical model that fuses the three dimensions of space and the one dimension of time into a single four-dimensional continuum. Spacetime diagrams are useful in visualizing and understanding relativistic effects, such as how different observers perceive where and when events ...

  6. Computational complexity theory - Wikipedia

    en.wikipedia.org/.../Computational_complexity_theory

    Continuous complexity theory can also refer to complexity theory of the use of analog computation, which uses continuous dynamical systems and differential equations. [18] Control theory can be considered a form of computation and differential equations are used in the modelling of continuous-time and hybrid discrete-continuous-time systems.

  7. Novikov self-consistency principle - Wikipedia

    en.wikipedia.org/wiki/Novikov_self-consistency...

    Outer Wilds (2019): A video game involving time travel which does not follow the principle, causing a game over if the player experiments to test it. All time travel in the Hallmark Channel original series The Way Home follows the Novikov self-consistency principle. Two of the main characters can travel backwards in time by jumping into a pond ...

  8. Quantum spacetime - Wikipedia

    en.wikipedia.org/wiki/Quantum_spacetime

    familiar from quantum mechanics but interpreted in this context as coordinates of a quantum space or spacetime. These relations were proposed by Roger Penrose in his earliest spin network theory of space. It is a toy model of quantum gravity in 3 spacetime dimensions (not the physical 4) with a Euclidean (not the physical Minkowskian) signature.

  9. Quantum complexity theory - Wikipedia

    en.wikipedia.org/wiki/Quantum_complexity_theory

    Quantum complexity theory is the subfield of computational complexity theory that deals with complexity classes defined using quantum computers, a computational model based on quantum mechanics. It studies the hardness of computational problems in relation to these complexity classes, as well as the relationship between quantum complexity ...