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  2. Space travel under constant acceleration - Wikipedia

    en.wikipedia.org/wiki/Space_travel_under...

    From the planetary frame of reference, the ship's speed will appear to be limited by the speed of light — it can approach the speed of light, but never reach it. If a ship is using 1 g constant acceleration, it will appear to get near the speed of light in about a year, and have traveled about half a light year in distance. For the middle of ...

  3. One-way speed of light - Wikipedia

    en.wikipedia.org/wiki/One-way_speed_of_light

    The two-way speed of light is the average speed of light from one point, such as a source, to a mirror and back again. Because the light starts and finishes in the same place, only one clock is needed to measure the total time; thus, this speed can be experimentally determined independently of any clock synchronization scheme.

  4. Interstellar travel - Wikipedia

    en.wikipedia.org/wiki/Interstellar_travel

    Later studies indicate that the top cruise velocity that can theoretically be achieved by a Teller-Ulam thermonuclear unit powered Orion starship, assuming no fuel is saved for slowing back down, is about 8% to 10% of the speed of light (0.08-0.1c). [44] An atomic (fission) Orion can achieve perhaps 3%-5% of the speed of light.

  5. Scalar field dark matter - Wikipedia

    en.wikipedia.org/wiki/Scalar_field_dark_matter

    Pie chart showing the fractions of energy in the universe contributed by different sources. Ordinary matter is divided into luminous matter (the stars and luminous gases and 0.005% radiation) and nonluminous matter (intergalactic gas and about 0.1% neutrinos and 0.04% supermassive black holes).

  6. Lorentz factor - Wikipedia

    en.wikipedia.org/wiki/Lorentz_factor

    Its initial value is 1 (when v = 0); and as velocity approaches the speed of light (v → c) γ increases without bound (γ → ∞). α (Lorentz factor inverse) as a function of velocity—a circular arc. In the table below, the left-hand column shows speeds as different fractions of the speed of light (i.e. in units of c). The middle column ...

  7. Observable universe - Wikipedia

    en.wikipedia.org/wiki/Observable_universe

    So if the matter that originally emitted the oldest CMBR photons has a present distance of 46 billion light-years, then the distance would have been only about 42 million light-years at the time of decoupling. The light-travel distance to the edge of the observable universe is the age of the universe times the speed of light, 13.8 billion light ...

  8. Rapidity - Wikipedia

    en.wikipedia.org/wiki/Rapidity

    Rapidity is the value of artanh(v / c) for velocity v and speed of light c. In special relativity, the classical concept of velocity is converted to rapidity to accommodate the limit determined by the speed of light. Velocities must be combined by Einstein's velocity-addition formula. For low speeds, rapidity and velocity are almost exactly ...

  9. 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.