Cosma / Communication / Knowledge / Realm / Physical / Law / Relativity



What is relativity? Einstein’s mind-bending theory explained (Dan Falk, Mach, NBC News)
The Theory of Relativity (Ask an Astronomer, Cornell University)


relativity : a theory which is based on the two postulates (1) that the speed of light in a vacuum is constant and independent of the source or observer and (2) that the mathematical forms of the laws of physics are invariant in all inertial systems and which leads to the assertion of the equivalence of mass and energy and of change in mass, dimension, and time with increased velocity — called also special relativity, special theory of relativity — Webster

OneLook, Free Dictionary, Wiktionary


Roget’s II (, Merriam-Webster Thesaurus, Visuwords


Relativity, generally refers to the theory of relativity usually encompasses two interrelated theories by Albert Einstein: special relativity and general relativity.

Special relativity applies to elementary particles and their interactions, describing all their physical phenomena except gravity.

General relativity explains the law of gravitation and its relation to other forces of nature. It applies to the cosmological and astrophysical realm, including astronomy.

The theory transformed theoretical physics and astronomy during the 20th century, superseding a 200-year-old theory of mechanics created primarily by Isaac Newton. It introduced concepts including spacetime as a unified entity of space and time, relativity of simultaneity, kinematic and gravitational time dilation, and length contraction.

In the field of physics, relativity improved the science of elementary particles and their fundamental interactions, along with ushering in the nuclear age. — Wikipedia

Encyclopædia Britannica

Relativity Theory (Eric Weisstein’s World of Physics, Wolfram Research)









The Collected Papers of Albert Einstein (California Institute of Technology)


WorldCat, Library of Congress, UPenn Online Books, Open Library





Special Relativity Course (Minute Physics)

Crash Course Physics (YouTube)

Einstein, Oppenheimer, Feynman: Physics in the 20th Century (MIT OCW Physics)
Introduction to Nuclear and Particle Physics (MIT OCW Physics)
Relativity (MIT OCW Physics)
OER Commons: Open Educational Resources


Science Daily,, NPR Archives









More News …

Albert Einstein News -- ScienceDaily Albert Einstein in the News. Research institutes have been testing Albert Einstein's theory of special relativity and general relativity. Was Albert Einstein right?

  • Matter and antimatter seem to respond equally to...
    on January 5, 2022 at 4:14 pm

    As part of an experiment to measure -- to an extremely precise degree -- the charge-to-mass ratios of protons and antiprotons, researchers have found that, within the uncertainty of the experiment, matter and antimatter respond to gravity in the same way.

  • Resolving the black hole ‘fuzzball or...
    on January 4, 2022 at 4:22 pm

    Black holes really are giant fuzzballs, a new study says. The study attempts to put to rest the debate over Stephen Hawking's famous information paradox, the problem created by Hawking's conclusion that any data that enters a black hole can never leave. This conclusion accorded with the laws of thermodynamics, but opposed the fundamental laws of quantum mechanics.

  • Machine learning decodes tremors of the universe
    on December 9, 2021 at 7:25 pm

    Researchers train a neural network to estimate -- in just a few seconds -- the precise characteristics of merging black holes based on their gravitational-wave emissions. The network determines the masses and spins of the black holes, where in the sky, at what angle, and how far away from Earth the merger took place.

  • Gravitational waves could be key to answering why...
    on December 8, 2021 at 4:03 pm

    If researchers can detect Q-balls in gravitational waves, it could help explain why more matter than anti-matter was left over after the Big Bang.

  • Jet from giant galaxy M87: Computer modelling...
    on November 4, 2021 at 6:01 pm

    An enormous jet of particles emitted by the giant galaxy M87 can be observed astronomically in various wavelengths. Scientists have developed a theoretical model of the morphology of this jet using complex supercomputer calculations. The images from these calculations provide an unprecedented match with astronomical observations and confirm Einstein's theory of general relativity. - latest science and technology news stories internet news portal provides the latest news on science including: Physics, Nanotechnology, Life Sciences, Space Science, Earth Science, Environment, Health and Medicine.

  • Tug of sun, moon could be driving plate motions...
    on January 21, 2022 at 10:57 pm

    A study led by geophysicist Anne M. Hofmeister in Arts & Sciences at Washington University in St. Louis proposes that imbalanced forces and torques in the Earth-moon-sun system drive circulation of the whole mantle.

  • Finding a link between emissions taxes and R&D...
    on January 21, 2022 at 6:34 pm

    Addressing climate change is a massive and daunting challenge. But many economists say gradually increasing taxes on emissions would significantly reduce the amount of greenhouse gas spewed into the air at the lowest economic cost.

  • A nonlinear-transport perspective of...
    on January 21, 2022 at 3:39 pm

    Combining topological states of matter with strong electron correlation promises many exotic phenomena such as charge fractionalization, excitonic instability, and axionic excitation. Layered transition-metal pentatellurides ZrTe5 and HfTe5 were found to be close to an accidental topological semimetal phase with low carrier density. Even in a relatively low magnetic field, they can form highly degenerated Landau levels and dramatically enhance the correlation effect of Dirac electrons therein. […]

  • Why you might want to consider a pilgrimage for...
    on January 21, 2022 at 3:30 pm

    We have been living in a COVID-19 pandemic world for two years—and almost everything about our lives has been affected. Travel and holidays in particular have been constrained through border closures and lockdowns. It's too early to say what effect this may have on overseas travel long term. But one form of travel that is forecast to grow in popularity is pilgrimage.

  • Savannas suffer greater loss and fragmentation...
    on January 21, 2022 at 2:49 pm

    Savannas are ecosystems characterized by a ground layer dominated by grasses and an open canopy of trees that allows direct sun to penetrate to the understory. Several national environmental policies have been put in place in China aiming for landscape protection, but with possible negative consequences for remaining intact savannas in Yunnan.


Here are links to pages about closely related subjects.

Knowledge Realm


Law (Constant) Relativity
Force Gravity, Electromagnetism (Light, Color)
Matter (Microscope) Molecule, Atom (Periodic Table), Particle

Universe (Astronomical Instrument)
Galaxy Milky Way, Andromeda
Planetary System Star, Brown Dwarf, Planet, Moon

Our Neighborhood
Solar System Sun
Terrestrial Planet Mercury, Venus, Earth (Moon), Mars
Asteroid Belt Ceres, Vesta
Jovian Planet Jupiter, Saturn, Uranus, Neptune
Trans-Neptunian Object
Kuiper Belt Pluto, Haumea, Makemake
Scattered Disc Eris, Sedna, Planet X
Oort Cloud Etc. Scholz’s Star
Small Body Comet, Centaur, Asteroid


1.   The resources on this page are are organized by a classification scheme developed exclusively for Cosma.