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Fundamental physics,
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Explore measured constants, characteristic particle scales and theoretical physical reference points.
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- Entities
- 19
- Most common primary scale
- Weight & gravity
- Common measurements
- Length, One transition period, Mass, Single-photon transition energy, Force, Temperature
Within this category's most common primary scale, explore Single DNA molecule stretching force at 5 × 10⁻¹¹ N and Thrust of an ionocraft lifter at 0.2 N. These are navigation anchors, not universal category limits.
19 entities in this category, ordered by name.
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19 measured entities
Browse fundamental physics
Bohr radius52.92 pmThe Bohr radius is a fundamental physical constant representing the most probable distance between the nucleus and the electron in a hydrogen atom according to early quantum theory.
Caesium-133 clock transition108.8 psThe caesium-133 clock transition is the specific change in energy state of a caesium-133 atom that defines the duration of one second in the International System of Units.Electron9.109 × 10⁻³¹ kgAn electron is a fundamental subatomic particle with a negative electric charge, found in atoms and responsible for electricity and chemical bonding.Hydrogen 21 cm hyperfine transition5.873 × 10⁻⁶ eVThis is a change in the energy state of neutral hydrogen atoms that produces or absorbs radio waves, widely used in radio astronomy.
Neutron1.675 × 10⁻²⁷ kgA neutron is a type of subatomic particle found in atomic nuclei, carrying no electric charge and playing a key role in holding nuclei together.Photon pressure thrust per kilowatt6.7 × 10⁻⁶ NPhoton pressure thrust per kilowatt is the force generated when one kilowatt of light is absorbed or reflected, due to photon momentum.
Planck length1.616 × 10⁻³⁵ mThe Planck length is a scale formed from fundamental physical constants.Planck mass21.76 µgThe Planck mass is a theoretical mass scale derived from fundamental constants, significant in discussions of quantum gravity.Planck temperature1.417 × 10³² KThe Planck temperature is a theoretical temperature scale at which quantum gravitational effects are expected to become important.
Proton1.682 fmA proton is a positively charged particle found in the nucleus of atoms, made up of quarks.Radiation pressure on a laser mirror7 × 10⁻⁶ NRadiation pressure on a laser mirror is the force exerted by a laser beam as its photons strike and reflect from the mirror.Raindrop aerodynamic drag0.0003 NRaindrop aerodynamic drag is the force exerted by air resistance on a falling raindrop as it moves through the atmosphere.
Single DNA molecule stretching force5 × 10⁻¹¹ NSingle DNA molecule stretching force is the force required to extend a single DNA strand under controlled laboratory conditions.Snowflake aerodynamic drag1 × 10⁻⁶ NSnowflake aerodynamic drag is the resistive force experienced by a falling snowflake as it moves through air.Soap film pull on a wire0.006 NSoap film pull on a wire is the force created by the surface tension of a soap film stretched across a wire frame.Strontium-87 optical clock transition1.779 eVThe strontium-87 optical clock transition is an energy change between two quantum states of strontium atoms that can set the timing of an optical atomic clock.Thrust of a gridded ion engine0.09 NThe thrust of a gridded ion engine is the force generated by accelerating ions through electrostatic grids to provide propulsion in space.Thrust of a Hall-effect satellite thruster0.1 NThe thrust of a Hall-effect satellite thruster is the force produced by accelerating ions with a magnetic field to propel a spacecraft.Thrust of an ionocraft lifter0.2 NThe thrust of an ionocraft lifter is the upward force generated by moving ions through air using high voltage, allowing the device to lift itself.