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Forty radioisotopes have been characterized, with the most stable, besides 176 Lu, being 174 Lu with a half-life of 3.31 years, and 173 Lu with a half-life of 1.37 years. All of the remaining radioactive isotopes have half-lives that are less than 9 days, and the majority of these have half-lives that are less than half an hour.
The diagram also shows considerable evolution through time. The red sequence earlier in the evolution of the universe was more constant in color across magnitudes and the blue cloud was not as uniformly distributed but showed sequence progression. One of five patches of sky covered by the COMBO-17 survey. [4]
Lutetium is a chemical element; it has symbol Lu and atomic number 71. It is a silvery white metal , which resists corrosion in dry air, but not in moist air. Lutetium is the last element in the lanthanide series, and it is traditionally counted among the rare earth elements ; it can also be classified as the first element of the 6th-period ...
In 2002, Karl Glazebrook and Ivan Baldry determined that the average color of the universe was a greenish white, but they soon corrected their analysis in a 2003 paper in which they reported that their survey of the light from over 200,000 galaxies averaged to a slightly beigeish white. [3]
The four pigments in a bird's cone cells (in this example, estrildid finches) extend the range of color vision into the ultraviolet. [1]Tetrachromacy (from Ancient Greek tetra, meaning "four" and chroma, meaning "color") is the condition of possessing four independent channels for conveying color information, or possessing four types of cone cell in the eye.
When colors are displayed in the CIE 1931 XYZ color space, additive mixture results in color along the line between the colors being mixed. By mixing any three colors, one can therefore create any color contained in the triangle they describe – this is called the gamut formed by those three colors, which are called primary colors. Any colors ...
An entirely different approach was needed for the much older problem of finding the number of colors needed for the plane or sphere, solved in 1976 as the four color theorem by Haken and Appel. On the sphere the lower bound is easy, whereas for higher genera the upper bound is easy and was proved in Heawood's original short paper that contained ...
The Friedmann–Lemaître–Robertson–Walker metric (FLRW; / ˈ f r iː d m ə n l ə ˈ m ɛ t r ə ... /) is a metric that describes a homogeneous, isotropic, expanding (or otherwise, contracting) universe that is path-connected, but not necessarily simply connected.