physics-databases

name	physics-databases
description	Query physics databases — NIST CODATA constants, NIST Chemistry WebBook, Materials Project, Particle Data Group (PDG), OEIS sequences. Always use these instead of hardcoding physical constants.
category	physics
version	1.0.0
author	Synthetic Sciences
license	MIT
tags	["NIST","CODATA","Physical Constants","Database","Materials Project","PDG"]
dependencies	["scipy>=1.11.0","numpy>=1.24.0"]

Physics Databases

Overview

Access physical constants and reference data from authoritative databases. Never hardcode physical constants — always query from scipy.constants (CODATA 2018) or NIST APIs.

CRITICAL: Always Use Database Values

• NEVER type physical constants from memory
• ALWAYS use scipy.constants or NIST lookup
• Constants change between CODATA editions (e.g., 2014 → 2018 → 2022)

Core Workflows

1. CODATA Physical Constants (scipy.constants)

from scipy import constants as const

# Fundamental constants
print("=== Fundamental Constants (CODATA 2018) ===")
print(f"Speed of light:       c  = {const.c:.10e} m/s")
print(f"Planck constant:      h  = {const.h:.10e} J·s")
print(f"Reduced Planck:       ℏ  = {const.hbar:.10e} J·s")
print(f"Boltzmann constant:   k  = {const.k:.10e} J/K")
print(f"Gravitational const:  G  = {const.G:.10e} m³/(kg·s²)")
print(f"Elementary charge:    e  = {const.e:.10e} C")
print(f"Electron mass:        mₑ = {const.m_e:.10e} kg")
print(f"Proton mass:          mₚ = {const.m_p:.10e} kg")
print(f"Neutron mass:         mₙ = {const.m_n:.10e} kg")
print(f"Vacuum permittivity:  ε₀ = {const.epsilon_0:.10e} F/m")
print(f"Vacuum permeability:  μ₀ = {const.mu_0:.10e} H/m")
print(f"Avogadro number:      Nₐ =  mol⁻¹")
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2. Unit Conversions

# Energy conversions
print("\n=== Energy Conversions ===")
print(f"1 eV  = {const.eV:.10e} J")
print(f"1 cal = {const.calorie:.6f} J")
print(f"1 BTU = {const.Btu:.6f} J")
print(f"1 erg = {const.erg:.10e} J")

# Length conversions
print("\n=== Length Conversions ===")
print(f"1 Å   = {const.angstrom:.10e} m")
print(f"1 au  = {const.au:.6e} m")  # astronomical unit
print(f"1 ly  = {const.light_year:.6e} m")
print(f"1 pc  = {const.parsec:.6e} m")

# Temperature
print(f"\n0°C = {const.zero_Celsius:.2f} K")

# Pressure
print(f"\n1 atm = {const.atm:.2f} Pa")
print(f"1 bar = {const.bar:.2f} Pa")
print(f"1 torr =  Pa")

3. Look Up Any CODATA Constant

# Search by name
def find_constant(keyword):
    """Search CODATA constants by keyword."""
    results = []
    for name, (value, unit, uncertainty) in const.physical_constants.items():
        if keyword.lower() in name.lower():
            results.append((name, value, unit, uncertainty))
            print(f"  {name}")
            print(f"    = {value:.10e} {unit}")
            print(f"    ± {uncertainty:.4e}")
    return results

print("Searching for 'Bohr':")
find_constant("Bohr")

print("\nSearching for 'magnetic moment':")
find_constant("magnetic moment")

4. Materials Project API

# pip install mp-api
# Requires API key: https://materialsproject.org/api

def query_materials_project(formula, api_key=None):
    """
    Query Materials Project for material properties.
    Set MP_API_KEY environment variable or pass api_key.
    """
    try:
        from mp_api.client import MPRester
        import os

        key = api_key or os.environ.get('MP_API_KEY')
        if not key:
            print("Set MP_API_KEY environment variable")
            return None

        with MPRester(key) as mpr:
            docs = mpr.summary.search(formula=[formula])
            for doc in docs[:5]:
                print(f"  {doc.material_id}: {doc.formula_pretty}")
                print(f"    Space group: {doc.symmetry.symbol}")
                print(f"    Energy above hull: {doc.energy_above_hull:.4f} eV/atom")
                print(f"    Band gap: {doc.band_gap:.3f} eV")
                print(f"    Density: {doc.density:.3f} g/cm³")
            return docs
    except ImportError:
        print()
         

5. Particle Data Group (PDG)

# Key particle properties (from PDG 2024)
# These are reference values — for precision work, check pdg.lbl.gov

particles = {
    'electron': {
        'mass_MeV': 0.51099895,
        'charge': -1,
        'spin': 0.5,
        'lifetime': 'stable',
    },
    'proton': {
        'mass_MeV': 938.27208816,
        'charge': +1,
        'spin': 0.5,
        'lifetime': 'stable (> 10^34 years)',
    },
    'neutron': {
        'mass_MeV': 939.56542052,
        'charge': 0,
        'spin': 0.5,
        'lifetime_s': 878.4,  # ~14.6 minutes
    },
    'muon': {
        'mass_MeV': 105.6583755,
        'charge': -1,
        'spin': 0.5,
        'lifetime_s': 2.1969811e-6,
    },
    'pion_charged': {
        'mass_MeV': 139.57039,
        'charge': +1,
        'spin': 0,
        'lifetime_s': 2.6033e-8,
    },
    'W_boson': {
        'mass_GeV': ,
        : +,
        : ,
    },
    : {
        : ,
        : ,
        : ,
    },
    : {
        : ,
        : ,
        : ,
    },
}

6. Astronomical Constants

# Solar system data (IAU 2015 values)
print("\n=== Astronomical Constants ===")
print(f"Solar mass:    M☉ = 1.98892e30 kg")
print(f"Solar radius:  R☉ = 6.9634e8 m")
print(f"Solar luminosity: L☉ = 3.828e26 W")
print(f"Earth mass:    M⊕ = 5.9722e24 kg")
print(f"Earth radius:  R⊕ = 6.3781e6 m")
print(f"Moon mass:     M☾ = 7.342e22 kg")
print(f"AU:            1 AU = {const.au:.6e} m")

# For precise values, use astropy:
# from astropy import constants as astro_const
# print(astro_const.M_sun)

Quick Reference

Constant	Symbol	Value	scipy.constants
Speed of light	c	2.998×10⁸ m/s	const.c
Planck	h	6.626×10⁻³⁴ J·s	const.h
Boltzmann	k_B	1.381×10⁻²³ J/K	const.k
Gravitational	G	6.674×10⁻¹¹ m³/(kg·s²)	const.G
Elementary charge	e	1.602×10⁻¹⁹ C	const.e
Electron mass	m_e	9.109×10⁻³¹ kg	const.m_e
Proton mass	m_p	1.673×10⁻²⁷ kg	const.m_p
Avogadro	N_A	6.022×10²³ mol⁻¹	const.N_A
Gas constant	R	8.314 J/(mol·K)	const.R
1 eV	—	1.602×10⁻¹⁹ J	const.eV
1 Å	—	1.0×10⁻¹⁰ m	const.angstrom

Tips

1. Always from scipy import constants as const — never type values manually
2. Check units: const.physical_constants['Bohr radius'] returns (value, unit, uncertainty)
3. For astrophysics: use astropy.constants for additional astronomical constants
4. For materials: use mp-api to query the Materials Project database
5. Cite your source: "CODATA 2018 via scipy.constants" or "PDG 2024"