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  2. Speed of electricity - Wikipedia

    en.wikipedia.org/wiki/Speed_of_electricity

    The speed at which energy or signals travel down a cable is actually the speed of the electromagnetic wave traveling along (guided by) the cable. I.e., a cable is a form of a waveguide. The propagation of the wave is affected by the interaction with the material(s) in and surrounding the cable, caused by the presence of electric charge carriers ...

  3. Breakthrough Starshot - Wikipedia

    en.wikipedia.org/wiki/Breakthrough_Starshot

    The ultra-light StarChip robotic nanocraft, fitted with light sails, are planned to travel at speeds of 20% [1] [6] [38] [5] and 15% [5] of the speed of light, taking between 20 and 30 years to reach the star system, respectively, and about 4 years to notify Earth of a successful arrival. [6]

  4. Speed of light - Wikipedia

    en.wikipedia.org/wiki/Speed_of_Light

    The speed of light is the upper limit for the speeds of objects with positive rest mass, and individual photons cannot travel faster than the speed of light. [39] This is experimentally established in many tests of relativistic energy and momentum. [40]

  5. Speed - Wikipedia

    en.wikipedia.org/wiki/Speed

    The fastest possible speed at which energy or information can travel, according to special relativity, is the speed of light in vacuum c = 299 792 458 metres per second (approximately 1 079 000 000 km/h or 671 000 000 mph). Matter cannot quite reach the speed of light

  6. Mass–energy equivalence - Wikipedia

    en.wikipedia.org/wiki/Mass–energy_equivalence

    The formula defines the energy E of a particle in its rest frame as the product of mass (m) with the speed of light squared (c 2). Because the speed of light is a large number in everyday units (approximately 300 000 km/s or 186 000 mi/s), the formula implies that a small amount of mass corresponds to an enormous amount of energy.

  7. Energy - Wikipedia

    en.wikipedia.org/wiki/Energy

    Energy (from Ancient Greek ἐνέργεια (enérgeia) 'activity') is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat and light. Energy is a conserved quantity—the law of conservation of energy states that energy can be converted in form, but ...

  8. Interstellar travel - Wikipedia

    en.wikipedia.org/wiki/Interstellar_travel

    As of January 20, 2023, Voyager 1, the farthest human-made object from Earth, is 163 AU away, exiting the Solar System at a speed of 17 km/s (0.006% of the speed of light). [ 1 ] The closest known star, Proxima Centauri , is approximately 268,332 AU away, or over 9,000 times farther away than Neptune.

  9. Energy density - Wikipedia

    en.wikipedia.org/wiki/Energy_density

    This energy is described by E = mc 2, where c is the speed of light. In terms of density, m = ρV , where ρ is the volumetric mass density, V is the volume occupied by the mass. This energy can be released by the processes of nuclear fission (~ 0.1%), nuclear fusion (~ 1%), or the annihilation of some or all of the matter in the volume V by ...