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In physics, the Planck time (tP), is the unit of time in the system of natural units known as Planck units. It is the time it would take a photon travelling at the speed of light in a vacuum to cross a distance equal to the Planck length.[1] The unit is named after Max Planck.
It is defined[1] as
- Failed to parse (Missing texvc executable; please see math/README to configure.): t_P = \sqrt{\frac{\hbar G}{c^5}} \approx 5.39121(40) \times 10^{-44} \mbox{ s}
where:
- Failed to parse (Missing texvc executable; please see math/README to configure.): \hbar = h / 2 \pi
is the reduced Planck constant
- Failed to parse (Missing texvc executable; please see math/README to configure.): G
is the gravitational constant
- Failed to parse (Missing texvc executable; please see math/README to configure.): c
is the speed of light in a vacuum
- Failed to parse (Missing texvc executable; please see math/README to configure.): t_P
is in seconds.
- The two digits between the parentheses denote the uncertainty in the last two digits of the value.
Physical significance
The Planck time is simply the time it takes a beam of light to travel a Planck length. See the corresponding section for that unit for details. As of 2006, the smallest unit of time that has been directly measured is on the attosecond (10−18 s) time scale, or around 1026 Planck times.[2][3] There is also speculation that a Planck time after the Big Bang, that statements can be made about the universe displaying properties equal to some of the other Planck units.[4][5]
One Planck time should be the smallest measurable time bit, according to quantum theory. But, according to news reports, analyses of Hubble Space Telescope Deep Field images in 2003 brought up a discrepancy. Images should have been blurry at very far distances, but -the news articles stated- weren't, challenging the theory that Planck time is the smallest measurable time bit in the universe.[6]
References
ca:Temps de Planck
es:Tiempo de Planck fr:Temps de Planck ko:플랑크 시간 it:Tempo di Planck la:Tempus planckianum hu:Planck-idő nl:Plancktijd ja:プランク時間 no:Planck-tid nn:Plancktid pl:Czas Plancka ru:Планковское время sk:Planckov čas fi:Planckin aika vi:Thời gian Planck
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