Speed of light =299792458m/s 0r approx 300000km/sec
Second= 9192631770 cycles of the standard caesium 133 atom(55) transition (electron vibration pulse)- in future optical clocks because of less uncertainty
Metre= the length of the path travelled by light in a vacuum during a time interval of 1/299792458 of a second
Pm=Picometer unit of length equivalent to one trillionth of a meter.
NM=nanometre unit of length equal to one billionth of a meter.
Micrometer unit of length equals one millionth of a metre.
Millimetre unit of length equals to 1000th of a metre
Centimetre unit of length is equals to 100th of a metre
Zetta meter 10^21m
Micro 10^-6 – chromosome level
Nano 10^-9 – polymer of DNA level
Pico 10^-12- gamma ray wavelength level
Smallest length theorised= PLANCK LENGTH = 1.6×10^-35 metres
If atom is size of earth than an proton of object in that earth would be a planck length
Last size where gravity would have an effect -size of string in string theory
Space time fabric =9.5 x 10^-36