# 4 List of physical constants

The following table lists all of the physical constants which are defined by default in Pyxplot:

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Name | Description | Approximate Value
--- | --- | ---
`e` |  |
`euler` | The Euler constant |
`false` | Boolean truth value | 0
`goldenRatio` | The golden ratio |
`i` | The square-root of |
`phy.alpha` | The fine-structure constant |
`phy.c` | The speed of light |
`phy.epsilon_0` | The permittivity of free space |
`phy.G` | The gravitational constant |
`phy.g` | The mean terrestrial acceleration due to gravity |
`phy.h` | The Planck constant |
`phy.hbar` | The Planck constant |
`phy.kB` | The Boltzmann constant |
`phy.Lsun` | The luminosity of the Sun |
`phy.Msun` | The mass of the Sun |
`phy.mu_0` | The permeability of free space |
`phy.mu_b` | The Bohr magneton |
`phy.m_e` | The mass of the electron |
`phy.m_muon` | The mass of the muon |
`phy.m_n` | The mass of the neutron |
`phy.m_p` | The mass of the proton |
`phy.m_u` | The unified mass constant |
`phy.NA` | Avogadro’s number |
`phy.q` | The fundamental charge |
`phy.R` | The gas constant |
`phy.Rsun` | The radius of the Sun |
`phy.Ry` | The Rydberg constant |
`phy.sigma` | The Stefan-Boltzmann constant |
`pi` |  |
`true` | Boolean truth value | 1
`version` | Pyxplot version string | “0.9.2”

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