Radioactive isotopes used in absolute dating
Radioactive isotopes used in absolute dating - Over 50 naked women
Shorter than violet you would see the ultraviolet, that which gives us tans and sunburns, and then you would encounter much more dangerous X-ray radiation and finally deadly gamma rays.
The use of various radioisotopes allows the dating of biological and geological samples with a high degree of accuracy.
The visual spectrum of light, however, is but a tiny portion of the whole picture, of a huge spectrum of radiation that extends in both directions from the edges of the rainbow.
If with superhuman eyes you could see beyond red, you would encounter the "infrared" -- felt as heat on the skin -- which would merge gradually into the familiar "radio" portion of the spectrum.
Miners in Germany believed little fellows like this one had stopped them extracting copper and silver from nickel and cobalt arsenides.
Fortunately George Brandt and Axel Cronstedt took a more scientific approach to the problem and discovered two new elements. Nickel is present in metallic meteorites and so has been in use since ancient times.
However, the principle of carbon-14 dating applies to other isotopes as well.
Potassium-40 is another radioactive element naturally found in your body and has a half-life of 1.3 billion years.
"Spectra" is embedded with links that will take you back to the appropriate parts of the above two sites. The classic colors red, orange, yellow, green, blue, and violet connect in a seemingly infinite number of shades, one blending smoothly into the next.
Together they constitute the "visual spectrum" (or "optical spectrum") because it is the part of the full spectrum that is seen with the human eye.
Archbishop Ussher took the genealogies of Genesis, assuming they were complete, and calculated all the years to arrive at a date for the creation of the earth on Sunday, October 23, 4004 B. Of course, even assuming the method was valid, such an exact date is not possible from the genealogies of the Bible (Ussher assumed all the years the patriarchs lived were exactly 365.25 days long and that they all died the day before their next birthday).
There are a number of other assumptions implicit in the calculation.
The age of the earth has been a topic of debate among Christians over the last two centuries.