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 Automatic translation  Automatic translation Category: universe
Updated December 05, 2021
Special relativity

Image: The special relativity equation E=mc2 or E2=m2c4+p2c2 or m=E/c2 or Δm=ΔE/c2 and the Lorentz factor γ=1/√1-v2/c2 apply to very many concepts in physics.

  Luminiferous Ether

Image: The luminiferous ether was imagined by physicists as the invisible "vapor" filling the universe and serving as a support for light.
This immobile ether was a landmark in which electromagnetic phenomena took place. Einstein vigorously rejected the stationary nature of the ether defended by Lorentz because it was contrary to the principle of relativity.

   Speed of light

Image: objects moving at speed c will also move at speed c in all frames of reference for all observers.

Lorentz factor

Image: The Lorentz factor curve shows an asymptote that tends to infinity when v=c

  travel of light between the Earth and the moon

Image: On the left of the image the observer on Earth sees the laser beam moving vertically and the pilot of the spaceship sees the beam moving in a zigzag way and thus cover a longer distance.

  Rayons cosmiques

Image: Sheaf of cosmic rays in the upper atmosphere. Muons have high energy, so the temporal dilation effect described by special relativity makes them observable on the surface of the Earth. Credit Lacosmo (original par Beetjedwars)

  Uranium nucleus fission

Image: In a nuclear fission reaction, a neutron is absorbed by a nucleus of uranium 235, transforming it into a nucleus of uranium 236. The latter, unstable, divides into two light elements (krypton 92 and barium 141) called fission fragments, and releases three neutrons. High energy gamma rays (not shown in the figure) are also produced.

Quarks and gluons

Image: The mass of quarks is only about 2 thousandths of the mass of nucleons. The gluons mediate the powerful force between the quarks. The kinetic energy and the strong interaction energy stir and hold the quarks together. Which means that the mass is the energy due to the frantic dance of the elementary particles. Credit APS/ Alan Stonebraker

  Deuterium tritium fusion

Image: In the tokamak (machine for harnessing fusion energy), hydrogen atoms can merge and generate energy. The mass balance shows that the mass after the fusion reaction is smaller than the mass before the reaction. The difference in mass turned into energy.


Image: The general principle of PET imaging is based on the use of tracers radiolabeled with a positron-emitting isotope (ß + radiation).

  Cone of light

Image: The cone of light or hypercone is a fundamental notion of the theory of relativity. It allows from an event, the distinction between past, future and inaccessible events. Relativistic events located inside the cone are causally related, on the other hand events located elsewhere are causally disconnected and cannot interact with events located in the cone.
Credit: GNU Free Documentation License


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