femtometer

Nucleus-scale measuring unit

A femtometer is one quadrillionth of a meter (10⁻¹⁵ meters).

At this scale, even atoms are enormous—a femtometer is roughly the diameter of a proton.

The unit appears almost exclusively in nuclear and particle physics, where it measures the size of atomic nuclei and the distances between subatomic particles.

nuclear

nucleus

Central controlling part

protonPositive nuclear particle
neutronUncharged nuclear particle
nuclear forceBinds subatomic particles

strong force · nuclear physics · fission · fusion · isotope · nucleon · atomic mass · radioactive decay · scattering · deuterium

scale

picometer

Trillionth of a meter

angstromSubatomic length unit
nanometerMetric unit, billion-fold smaller
subatomicSmaller than atoms

nucleus · wavelength · atomic nucleus · infinitesimal

particle

quark

Fundamental matter particle

gluonStrong force mediator
leptonFundamental particle without strong interactions
hadronQuark-containing subatomic particle

meson · baryon · neutrino · Higgs boson · antiparticle · electron · positron · muon · photon · boson

measurement

precision

Accuracy of measurement

metrologyScience of precise quantification
calibrationAdjusting for measurement accuracy
quantificationExpressing something numerically

spectroscopy · electron microscopy · particle accelerator · CERN · synchrotron · cross-section · accuracy · instrumentation · scientific notation · orders of magnitude

Opposites

scale of measurement

femtometerlight-year

Astronomical distance measure

parsec · megaparsec · astronomical unit · cosmic scale · observable universe

realm of physical phenomena

femtometercosmic scale

Universe-sized frame of reference

human scale · observable universe

Family

meter, femtosecond

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