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  2. List of time periods - Wikipedia

    en.wikipedia.org/wiki/List_of_time_periods

    This is a list of such named time periods as defined in various fields of study. These can be divided broadly into prehistorical periods and historical periods (when written records began to be kept).

  3. Science project - Wikipedia

    en.wikipedia.org/wiki/Science_project

    A science project is an educational activity for students involving experiments or construction of models in one of the science disciplines. Students may present their science project at a science fair, so they may also call it a science fair project. Science projects may be classified into four main types.

  4. Time in physics - Wikipedia

    en.wikipedia.org/wiki/Time_in_physics

    In the International System of Units (SI), the unit of time is the second (symbol: s). It has been defined since 1967 as "the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom", and is an SI base unit. [12]

  5. Time - Wikipedia

    en.wikipedia.org/wiki/Time

    Time is the continuous progression of existence that occurs in an apparently irreversible succession from the past, through the present, and into the future. [1] [2] [3] It is a component quantity of various measurements used to sequence events, to compare the duration of events (or the intervals between them), and to quantify rates of change of quantities in material reality or in the ...

  6. Unit of time - Wikipedia

    en.wikipedia.org/wiki/Unit_of_time

    The Jiffy is the amount of time light takes to travel one femtometre (about the diameter of a nucleon). The Planck time is the time that light takes to travel one Planck length. The TU (for time unit) is a unit of time defined as 1024 μs for use in engineering. The svedberg is a time unit used for sedimentation rates (usually

  7. Experimental testing of time dilation - Wikipedia

    en.wikipedia.org/wiki/Experimental_testing_of...

    By measuring their kinetic energy, mean muon velocities between 0.995 c and 0.9954 c were determined. Another measurement was taken in Cambridge, Massachusetts at sea-level. The time the muons need from 1917m to 0m should be about 6.4 μs. Assuming a mean lifetime of 2.2 μs, only 27 muons would reach this location if there were no time dilation.

  8. Geologic time scale - Wikipedia

    en.wikipedia.org/wiki/Geologic_time_scale

    The geologic time scale is a way of representing deep time based on events that have occurred throughout Earth's history, a time span of about 4.54 ± 0.05 Ga (4.54 billion years). [3] It chronologically organises strata, and subsequently time, by observing fundamental changes in stratigraphy that correspond to major geological or ...

  9. Long-term experiment - Wikipedia

    en.wikipedia.org/wiki/Long-term_experiment

    The William James Beal Germination Experiment has been running since 1879. It is the oldest on-going experiment in botany. It is scheduled for completion in 2100. The Godwin Plots experiment at the Wicken Fen reserve in Cambridgeshire, England, has been running since the 1920s and explores the differences between areas of vegetation which are never cut, and respectively all four, three or two ...