Changes

===Mass Change Associated With Energy Change===

===Mass Change Associated With Energy Change===

This is the famous formula "E=mc²".  At the end of Einstein's original 1905 paper on the subject<ref>http://www.fourmilab.ch/etexts/einstein/E_mc2/www/ "Does the Inertia of a Body Depend its Energy Content?"</ref>, he speculates on the possibility that the equation <math>E = m c^2</math>, which would normally be very hard to verify, could be verified with the extremely high energies of the newly discovered phenomenon of radioactivity.<ref>This equation is not related to [[quantum mechanics]].</ref>  In the 1910s, with the invention of the mass spectrometer, it became possible to measure masses of nuclei accurately.  This led to the clearing up of the mystery of atomic masses not being exact integers,and strongly suggested the existence of a "mass defect" (or "packing fraction") consistent with the mass-energy equivalence.  In the 1930s, experiments with known nuclear reactions showed a very accurate correlation between the masses of the nuclei involved and the energy released.  See [[Quantitative Analysis of Alpha Decay]].

This is the famous formula "E=mc²".  At the end of Einstein's original 1905 paper on the subject,<ref>http://www.fourmilab.ch/etexts/einstein/E_mc2/www/ "Does the Inertia of a Body Depend its Energy Content?"</ref> he speculates on the possibility that the equation <math>E = m c^2</math>, which would normally be very hard to verify, could be verified with the extremely high energies of the newly discovered phenomenon of radioactivity.<ref>This equation is not related to [[quantum mechanics]].</ref>  In the 1910s, with the invention of the mass spectrometer, it became possible to measure masses of nuclei accurately.  This led to the clearing up of the mystery of atomic masses not being exact integers,and strongly suggested the existence of a "mass defect" (or "packing fraction") consistent with the mass-energy equivalence.  In the 1930s, experiments with known nuclear reactions showed a very accurate correlation between the masses of the nuclei involved and the energy released.  See [[Quantitative Analysis of Alpha Decay]].

===Time Dilation===

===Time Dilation===

===Local Position Invariance===

===Local Position Invariance===

The ''equivalence principle'', which is the underpinning of gravity under general relativity, states that there is absolutely no perceived effect of gravity on an object in free fall, that is, in a gravitational field.  This has been tested many times, and is the basis of all space-time calculations in relativity.  But in 2019, it was reported to have been successfully tested in a gravitational field very much stronger than ever before.  The phenomenon is called ''local position invariance'', or LPI.  It was measured on the light emitted from a star called "S2", closely orbiting the "Sagittarius A*" black hole at the center of the galaxy.  The gravitational field that S2 is subject to is vastly more powerful than any other gravitational field that has been measured<ref>https://physics.aps.org/synopsis-for/10.1103/PhysRevLett.122.101102</ref>.

The ''equivalence principle'', which is the underpinning of gravity under general relativity, states that there is absolutely no perceived effect of gravity on an object in free fall, that is, in a gravitational field.  This has been tested many times, and is the basis of all space-time calculations in relativity.  But in 2019, it was reported to have been successfully tested in a gravitational field very much stronger than ever before.  The phenomenon is called ''local position invariance'', or LPI.  It was measured on the light emitted from a star called "S2", closely orbiting the "Sagittarius A*" black hole at the center of the galaxy.  The gravitational field that S2 is subject to is vastly more powerful than any other gravitational field that has been measured.<ref>https://physics.aps.org/synopsis-for/10.1103/PhysRevLett.122.101102</ref>

===Geodetic Precession===

===Geodetic Precession===