The Physics
Factbook
An encyclopedia of scientific essays

Age of the Universe

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Bibliographic Entry Result
(w/surrounding text)
Standardized
Result
Principles of Science. New York: Merril, 1979. "This occurred between 16 and 24 billion years ago"  16–24
billion years
World Book Multimedia Encyclopedia. CD-ROM. Chicago: World Book, 1998. "The universe began as the result of an explosion 10 billion to 20 billion years ago" 10–20
billion years
"Low Density Universe." Scientific American. 280 (January 1999). "… according to which our universe has been expanding for the past 12 billion years or so" 12
billion years
Guth, Alan H. The Inflationary Universe, Helix Books, 1997. "The estimated age of the universe was in the range of 2 billion years or so." [Value from the 1930s] 2
billion years
Origins Science. Jet Propulsion Laboratory. NASA. "NASA's Origins Program follows the 15-billion year long chain of events from the birth of the Universe at the Big Bang" 15
billion years
Hubble Space Telescope on Track for Measuring the Expansion Rate of the Universe. STScI/HST Public Information. NASA, 9 May 1996. "These new results yield ranges for the age of the Universe from 9-12 billion years, and 11-14 billion years, respectively." 9–14
billion years

There are varying opinions on the actual age of the universe. Current estimates range from 12 to 24 billion years. This is because the age of the universe is such a large number and therefore, difficult to estimate exactly. Also, no one was alive to measure the age of the universe so it must be approximated and figured out based on factors which are prone to error.

Another reason for the differences in values is that depending on which theory of creation you believe in, the universe has a different age. The "Big Bang Theory"is currently the most widely accepted theory of universal creation but some people believe in theories based on religion, etc.

One figure was very different from the others. This figure was estimated by the scientist Hubble in 1930. According to his calculations, the age of the universe was 2 billion years or less. Even a few years after he came up with this figure it was known that the actual age of the universe was much older. Since this time, the estimate has become much more accurate.

Rachel Hoover -- 1999

Bibliographic Entry Result
(w/surrounding text)
Standardized
Result
Clark, Stuart. "Star date: The minimum age of the Universe is calculated using a new radiometric approach." New Scientist. 7 February 2001. "Astronomers used the decay of uranium-238 for the first time to date an ancient star at about 12.5 billion years old."
"In the past, cosmologists have supplied the Universe's age. But their estimates range between 9 and 16 billion years because different researchers feed different assumptions into their models."
12.5
billion years
(new estimate)
11–14
billion years
(previous estimates)
Cayrel, R. et al. "Measurement of stellar age from uranium decay." Nature. (8 February 2001) Vol. 409, No. 6821. "The derived uranium abundance, log(U/H) = -13.7 ± 0.14 ± 0.12 yields an age of 12.5 ± 3 Gyr, though this is still model dependent." 12.5
billion years
Schwarzschild, Bertram. "WMAP Spacecraft Maps the Entire Cosmic Microwave Sky With Unprecedented Precision." Physics Today. Vol. 56, No. 4 (April 2003): 21. "The upshot of this new precision is a strong confirmation of the standard inflationary Big Bang scenario, but now with astonishing specificity. We are informed, for example, that the Big Bang occurred 13.7 ±0.2 billion years ago, and that the cmB [cosmic microwave background] is a snapshot of the cosmos 379 ±8 thousand years later." 13.7
billion years

Editor's Supplement -- 2001, 2003