Einsteins theory of relativity

Radium, the last metal in the alkaline earth metal group, has an intense white color and is extremely radioactive. In the dark, it glows and gives off a soft blue color. The French husband and wife chemist team Marie (1867-1934) and Pierre Curie (1859-1906) discovered radium in 1898. Along with the discovery of the electron and Albert Einsteins theory of relativity, the discovery of radium marked the beginning of the modern era of science. 

A theory is an explanation of a natural phenomenon based on many observations and investigations over time. You might have heard of Einsteins theory of relativity or the atomic theory. A theory states a broad principle of nature that has been supported over time. All theories are still subject to new experimental data and can be modified. Also, theories often lead to new conclusions. A theory is considered successful if it can be used to make predictions that are true. 

Keywords Mechanics Aristotle Archimedes Galileo Newton Hero of Alexandria Energy methods Einstein Theory of relativity Calculus of variations Strength of materials Plasticity... 

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