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1 day ago · Special relativity rests on two postulates: that the laws of physics are the same in all inertial (non-accelerating) reference frames; and that the velocity of light in empty space, c, is the same ...
3 days ago · Given what is known about modern physics today, it is quite easy to take for granted that the speed of light, approximately \( 3 \cdot 10^8\: \text{m}/\text{s} \), is the unwavering speed limit of the universe.
3 days ago · We call the emitted electrons as photoelectrons and the current they constitute as photocurrent. The phenomenon was first observed by Heinrich Hertz in 1880 and explained by Albert Einstein in 1905 using Max Planck's quantum theory of light.
2 days ago · General relativity, also known as the general theory of relativity and Einstein's theory of gravity, is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics. General relativity generalizes special relativity and refines Newton's law of universal gravitation ...
4 days ago · dark matter, a component of the universe whose presence is discerned from its gravitational attraction rather than its luminosity. Dark matter makes up 30.1 percent of the matter -energy composition of the universe; the rest is dark energy (69.4 percent) and “ordinary” visible matter (0.5 percent). Originally known as the “missing mass ...
- Adam Riess
- What is dark matter?Dark matter is a component of the universe whose presence is discerned from its gravitational attraction rather than its luminosity.
- What percentage of the matter-energy composition of the universe is made of dark matter?Dark matter makes up 30.1 percent of the matter-energy composition of the universe. The rest is dark energy (69.4 percent) and “ordinary” visible m...
- Who first inferred the existence of dark matter?Dark matter’s existence was first inferred by Swiss American astronomer Fritz Zwicky, who in 1933 discovered that the mass of all the stars in the...
- What are the types of dark matter?Two varieties of dark matter have been found to exist. The first variety is about 4.5 percent of the universe and made of the familiar baryons (i.e...
6 days ago · Tests of general relativity serve to establish observational evidence for the theory of general relativity. The first three tests, proposed by Albert Einstein in 1915, concerned the "anomalous" precession of the perihelion of Mercury, the bending of light in gravitational fields, and the gravitational redshift.
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3 days ago · Plaque at the Humboldt University of Berlin: "Max Planck, who discovered the elementary quantum of action h, taught here from 1889 to 1928." Intensity of light emitted from a black body. Each curve represents behavior at different body temperatures. The Planck constant h is used to explain the shape of these curves.
