Editing Picometre

{{Short description|Unit of length (10^-12 meters)}}
{{for|examples of things measuring between one and ten picometres|1 picometre}}
{{Infobox unit
| image    = [[File:Atom.svg|200px]]
| caption  = A simplified representation of a [[helium]] atom, having an estimated (calculated) diameter of 62 picometres<ref name="WebElementsSize">{{cite web | url = http://www.webelements.com/periodicity/atomic_radius | title = Atomic radius | work = WebElements: the periodic table on the web}}</ref>
| symbol   = pm
| standard = [[SI]]
| quantity = [[length]]
| units1   = [[SI base units]]
| inunits1 = {{val|1|e=-12|ul=m}}
| units2   = [[Natural units]]
| inunits2 = {{val|6.1877|e=22}}&nbsp;{{math|[[Planck length|<var>ℓ</var><sub>P</sub>]]}}<br /><!--
    -->&nbsp;&nbsp;&nbsp;{{val|1.8897|e=-2}}&nbsp;[[Bohr radius|''a''<sub>0</sub>]]
| units3   = [[imperial units|imperial]]/[[US customary units|US]]&nbsp;units
| inunits3 = {{convert|1|pm|in|disp=out|lk=on|sigfig=5}}
}}
{{Wiktionary|picometre}}

The '''picometre''' (international [[American and British English spelling differences#-re, -er|spelling]] as used by the [[International Bureau of Weights and Measures]]; [[SI]] symbol: '''pm''') or '''picometer''' ([[American and British English spelling differences#-re, -er|American spelling]]) is a [[unit of length]] in the [[International System of Units]] (SI), equal to {{val|1|e=-12|ul=m}}, or one trillionth {{nowrap|({{sfrac|{{val|1,000,000,000,000}}}})}} of a [[metre]], which is the [[SI base unit]] of length.

The picometre is one thousand [[femtometres]], one thousandth of a [[nanometre]] ({{nowrap|{{sfrac|{{val|1,000}}}}}}&nbsp;nm), one millionth of a [[micrometre]] (also known as a micron), one billionth of a [[millimetre]], and one trillionth of a metre.<ref>{{cite book | title = Dictionary of Distances | first1 = Elena | last1 = Deza | author1-link=Elena Deza |first2= Michel Marie | last2 = Deza | author2-link = Michel Deza | publisher = Elsevier | year =  2006 | isbn = 0-444-52087-2 | url = https://books.google.com/books?id=I-PQH8gcOjUC&q=stigma+bicron&pg=PA347 }}</ref> The symbol μμ was once used for it.<ref name="micromicro">{{cite web | url = https://www.ibiblio.org/units/ | title = How Many? A Dictionary of Units of Measurement | first = Russ | last = Rowlett | year = 2018 }}</ref> It is also one hundredth of an [[ångström]], an internationally known (but non-SI) unit of length.

==Use==
The picometre's length is of an order so small that its application is almost entirely confined to [[particle physics]], [[quantum physics]], chemistry, and [[acoustics]]. [[Atom]]s are between 62 and 520&nbsp;pm in diameter, and the typical [[bond length|length]] of a carbon–carbon [[covalent bond|single bond]] is 154 pm.  Smaller units still may be used to describe smaller particles (some of which are the components of atoms themselves), such as [[hadron]]s and the upper limits of possible size for [[fermion]] point particles.

The [[Laser Interferometer Space Antenna#Science goals|Laser Interferometer Space Antenna]] (LISA) probe is planned for launch in 2034 to directly detect [[gravitational wave]]s and will measure relative displacements with a resolution of 20 picometres over a distance of 2.5 gigametres, yielding a strain sensitivity of better than 1 part in 10<sup>20</sup>.

==References==
{{Reflist}}
{{SI units of length}}

[[Category:Metre]]
[[Category:Orders of magnitude (length)|-12]]