Title: Physical Constants

The GSL physical constants are defined as Ruby constants under the modules

For example, the GSL C constant GSL_CONST_MKSA_SPEED_OF_LIGHT is represented by a Ruby constant,

GSL_CONST_MKSA_SPEED_OF_LIGHT  ---> GSL::CONST::MKSA::SPEED_OF_LIGHT

The following lists a part of the constants. Most of the constants are defined both in the modules GSL::CONST::MKSA and GSL::CONST::CGSM. See also the GSL reference

Contents:

  1. Fundamental Constants
  2. Astronomy and Astrophysics
  3. Atomic and Nuclear Physics
  4. Measurement of Time
  5. Imperial Units
  6. Nautical Units
  7. Printers Units
  8. Volume
  9. Mass and Weight
  10. Thermal Energy and Power
  11. Pressure
  12. Viscosity
  13. Light and Illumination
  14. Radioactivity
  15. Force and Energy
  16. Prefixes
  17. Examples

1 Fundamental Constants

GSL::CONST::MKSA::SPEED_OF_LIGHT
The speed of light in vacuum, c.
GSL::CONST::MKSA::VACUUM_PERMEABILITY
The permeability of free space, \mu (not defined in GSL::CONST::CGSM).
GSL::CONST::MKSA::VACUUM_PERMITTIVITY
The permittivity of free space, \epsilon_0 (not defined in GSL::CONST::CGSM).
GSL::CONST::MKSA::PLANCKS_CONSTANT_H
Planck's constant, h.
GSL::CONST::MKSA::PLANCKS_CONSTANT_HBAR
Planck's constant divided by 2\pi, \hbar.
GSL::CONST::NUM::AVOGADRO
Avogadro's number
GSL::CONST::MKSA::FARADAY
The molar charge of 1 Faraday.
GSL::CONST::MKSA::BOLTZMANN
The Boltzmann constant, k.
GSL::CONST::MKSA::STEFAN_BOLTZMANN_CONSTANT
The Stefan-Boltzmann constant, \sigma.
GSL::CONST::MKSA::MOLAR_GAS
The molar gas constant, R_0.
GSL::CONST::MKSA::STANDARD_GAS_VOLUME
The standard gas volume, V_0.
GSL::CONST::MKSA::GAUSS
The magnetic field of 1 Gauss.

2 Astronomy and Astrophysics

GSL::CONST::MKSA::ASTRONOMICAL_UNIT
The length of 1 astronomical unit (mean earth-sun distance), AU.
GSL::CONST::MKSA::GRAVITATIONAL_CONSTANT
The gravitational constant, G.
GSL::CONST::MKSA::LIGHT_YEAR
The distance of 1 light-year, ly.
GSL::CONST::MKSA::PARSEC
The distance of 1 parsec, pc.
GSL::CONST::MKSA::GRAV_ACCEL
The standard gravitational acceleration on Earth, g.
GSL::CONST::MKSA::SOLAR_MASS
The mass of the Sun.

3 Atomic and Nuclear Physics

GSL::CONST::MKSA::ELECTRON_CHARGE
The charge of the electron, e.
GSL::CONST::CGSM::ELECTRON_CHARGE_ESU
The charge of the electron, e, in esu unit (not defined in GSL::CONST::MKSA).
GSL::CONST::MKSA::ELECTRON_VOLT
The energy of 1 electron volt, eV.
GSL::CONST::MKSA::UNIFIED_ATOMIC_MASS
The unified atomic mass, amu.
GSL::CONST::MKSA::MASS_ELECTRON
The mass of the electron, m_e.
GSL::CONST::MKSA::MASS_MUON
The mass of the muon, m_\mu.
GSL::CONST::MKSA::MASS_PROTON
The mass of the proton, m_p.
GSL::CONST::MKSA::MASS_NEUTRON
The mass of the proton, m_n.
GSL::CONST::NUM::FINE_STRUCTURE
The electromagnetic fine structure constant alpha.
GSL::CONST::MKSA::RYDBERG
The Rydberg constant, Ry, in units of energy. This is related to the Rydberg inverse wavelength R by Ry = h c R.
GSL::CONST::MKSA::THOMSON_CROSS_SECTION
The Thomson cross section of photon scattering by electrons.
GSL::CONST::MKSA::BOHR_RADIUS
The Bohr radius, a_0.
GSL::CONST::MKSA::ANGSTROM
The length of 1 angstrom.
GSL::CONST::MKSA::BARN
The area of 1 barn.
GSL::CONST::MKSA::BOHR_MAGNETON
The Bohr Magneton, mu_B.
GSL::CONST::MKSA::NUCLEAR_MAGNETON
The Nuclear Magneton, mu_N.
GSL::CONST::MKSA::ELECTRON_MAGNETIC_MOMENT
The absolute value of the magnetic moment of the electron, mu_e. The physical magnetic moment of the electron is negative.
GSL::CONST::MKSA::PROTON_MAGNETIC_MOMENT
The magnetic moment of the proton, mu_p.

4 Measurement of Time

GSL::CONST::MKSA::MINUTE
The number of seconds in 1 minute.
GSL::CONST::MKSA::HOUR
The number of seconds in 1 hour.
GSL::CONST::MKSA::DAY
The number of seconds in 1 day.
GSL::CONST::MKSA::WEEK
The number of seconds in 1 week.

5 Imperial Units

GSL::CONST::MKSA::INCH
The length of 1 inch.
GSL::CONST::MKSA::FOOT
The length of 1 foot.
GSL::CONST::MKSA::YARD
The length of 1 yard.
GSL::CONST::MKSA::MILE
The length of 1 mile.
GSL::CONST::MKSA::MIL
The length of 1 mil (1/1000th of an inch).

6 Nautical Units

GSL::CONST::MKSA::NAUTICAL_MILE
The length of 1 nautical mile.
GSL::CONST::MKSA::FATHOM
The length of 1 fathom.
GSL::CONST::MKSA::KNOT
The speed of 1 knot.

7 Printers Units

GSL::CONST::MKSA::POINT
The length of 1 printer's point (1/72 inch).
GSL::CONST::MKSA::TEXPOINT
The length of 1 TeX point (1/72.27 inch).

8 Volume

GSL::CONST::MKSA::ACRE
The area of 1 acre.
GSL::CONST::MKSA::LITER
The volume of 1 liter.
GSL::CONST::MKSA::US_GALLON
The volume of 1 US gallon.
GSL::CONST::MKSA::CANADIAN_GALLON
The volume of 1 Canadian gallon.
GSL::CONST::MKSA::UK_GALLON
The volume of 1 UK gallon.
GSL::CONST::MKSA::QUART
The volume of 1 quart.
GSL::CONST::MKSA::PINT
The volume of 1 pint.

9 Mass and Weight

GSL::CONST::MKSA::POUND_MASS
The mass of 1 pound.
GSL::CONST::MKSA::OUNCE_MASS
The mass of 1 ounce.
GSL::CONST::MKSA::TON
The mass of 1 ton.
GSL::CONST::MKSA::METRIC_TON
The mass of 1 metric ton (1000 kg).
GSL::CONST::MKSA::UK_TON
The mass of 1 UK ton.
GSL::CONST::MKSA::TROY_OUNCE
The mass of 1 troy ounce.
GSL::CONST::MKSA::CARAT
The mass of 1 carat.
GSL::CONST::MKSA::GRAM_FORCE
The force of 1 gram weight.
GSL::CONST::MKSA::POUND_FORCE
The force of 1 pound weight.
GSL::CONST::MKSA::KILOPOUND_FORCE
The force of 1 kilopound weight.
GSL::CONST::MKSA::POUNDAL
The force of 1 poundal.

10 Thermal Energy and Power

GSL::CONST::MKSA::CALORIE
The energy of 1 calorie.
GSL::CONST::MKSA::BTU
The energy of 1 British Thermal Unit, btu.
GSL::CONST::MKSA::THERM
The energy of 1 Therm.
GSL::CONST::MKSA::HORSEPOWER
The power of 1 horsepower.

11 Pressure

GSL::CONST::MKSA::BAR
The pressure of 1 bar.
GSL::CONST::MKSA::STD_ATMOSPHERE
The pressure of 1 standard atmosphere.
GSL::CONST::MKSA::TORR
The pressure of 1 torr.
GSL::CONST::MKSA::METER_OF_MERCURY
The pressure of 1 meter of mercury.
GSL::CONST::MKSA::INCH_OF_MERCURY
The pressure of 1 inch of mercury.
GSL::CONST::MKSA::INCH_OF_WATER
The pressure of 1 inch of water.
GSL::CONST::MKSA::PSI
The pressure of 1 pound per square inch.

12 Viscosity

GSL::CONST::MKSA::POISE
The dynamic viscosity of 1 poise.
GSL::CONST::MKSA::STOKES
The kinematic viscosity of 1 stokes.

13 Light and Illumination

GSL::CONST::MKSA::STILB
The luminance of 1 stilb.
GSL::CONST::MKSA::LUMEN
The luminous flux of 1 lumen.
GSL::CONST::MKSA::LUX
The illuminance of 1 lux.
GSL::CONST::MKSA::PHOT
The illuminance of 1 phot.
GSL::CONST::MKSA::FOOTCANDLE
The illuminance of 1 footcandle.
GSL::CONST::MKSA::LAMBERT
The luminance of 1 lambert.
GSL::CONST::MKSA::FOOTLAMBERT
The luminance of 1 footlambert.

14 Radioactivity

GSL::CONST::MKSA::CURIE
The activity of 1 curie.
GSL::CONST::MKSA::ROENTGEN
The exposure of 1 roentgen.
GSL::CONST::MKSA::RAD
The absorbed dose of 1 rad.

15 Force and Energy

GSL::CONST::MKSA::NEWTON
The SI unit of force, 1 Newton.
GSL::CONST::MKSA::DYNE
he force of 1 Dyne = 10^-5 Newton.
GSL::CONST::MKSA::JOULE
The SI unit of energy, 1 Joule.
GSL::CONST::MKSA::ERG
The energy 1 erg = 10^-7 Joule.

16 Prefixes

GSL::CONST::NUM::YOTTA
10^24
GSL::CONST::NUM::ZETTA
10^21
GSL::CONST::NUM::EXA
10^18
GSL::CONST::NUM::PETA
10^15
GSL::CONST::NUM::TERA
10^12
GSL::CONST::NUM::GIGA
10^9
GSL::CONST::NUM::MEGA
10^6
GSL::CONST::NUM::KILO
10^3
GSL::CONST::NUM::MILLI
10^-3
GSL::CONST::NUM::MICRO
10^-6
GSL::CONST::NUM::NANO
10^-9
GSL::CONST::NUM::PICO
10^-12
GSL::CONST::NUM::FEMTO
10^-15
GSL::CONST::NUM::ATTO
10^-18
GSL::CONST::NUM::ZEPTO
10^-21
GSL::CONST::NUM::YOCTO
10^-24

17 Example

The following program demonstrates the use of the physical constants in a calculation. In this case, the goal is to calculate the range of light-travel times from Earth to Mars.

require("gsl")
include GSL::CONST::MKSA

puts("In MKSA unit")

c  = SPEED_OF_LIGHT;
au = ASTRONOMICAL_UNIT;
minutes = MINUTE;

# distance stored in meters 
r_earth = 1.00 * au;  
r_mars  = 1.52 * au;

t_min = (r_mars - r_earth) / c;
t_max = (r_mars + r_earth) / c;

printf("light travel time from Earth to Mars:\n");
printf("c = %e [m/s]\n", c)
printf("AU = %e [m]\n", au)
printf("minutes = %e [s]\n", minutes)
printf("minimum = %.1f minutes\n", t_min / minutes);
printf("maximum = %.1f minutes\n\n", t_max / minutes);

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