Cosmology View

Views on Cosmology and Physics

site navigation menu


Light in a Vacuum


The Michelson Morley experiment confirmed there is no aether around the Earth affecting the propagation of light.

However, some still propose there must be something in in space supporting its propagation.

I have heard someone say, "if light is a wave then something must be waving."

It doesn't matter who said it, because the statement is so simple.

There is an oscillation in light, but not of particles.

What is Light?

James Clerk Maxwell defined light as the propagation of synchronized, perpendicular electric and magnetic fields

This mechanism is based the behavior of a collapsing electric field creating a magnetic field, and a collapsing magnetic field creating an electric field.

The propagation of these interacting fields continues until this energy is absorbed by matter.

Arvin Ash did a great video to visualize the interacting fields.

Why is the speed of light what it is? Maxwell equations visualized

Each wavelength of the propagation carries energy in the intensity of the wavelength.

Lori Gardi did an excellent description of the wavelength intensity carrying its energy in light.

Planck's Constant and the Nature of Light.

She has both a paper and YouTube video of that title.



In my opinion, she efficiently describes the nature of light, in more detail han apparent in just Maxwell's equations.

What is a Field?

Lori Gardi produced a YouTube video of that title.

Video includes a great visualization of an electric field.

Light in a Medium

Maxwell defined the propagation of light without ever requiring a specific medium, like aether, to support its propagation.

He actually defined 2 parameters for free space, or without a medium, using 2 Greek letters.

1) permittivity of free space; this is epsilon-nought.

2) permeability of free space; this is mu-nought.

He calculated the velocity of light, or c, from this equation.

It is an awkward task of describing, in words,  Greek letters with subscripts in a square root within in a denominator.

Here is a copy of the equation, from Wikipedia. (the link follows).

Here is the reference for the png and gif.

Maxwell's Equations

This page in Wikipedia has a useful .gif file that illustrates the interacting electric and magnetic fields in the propagation of light,
where  E=Electric, B=magnetic.

Here is a copy of that gif. A click or select will animate.

2 Defining the 2 Constants for Free Space.

Maxwell's term free space was replaced by the word vacuum.

2.1 Vacuum permittivity

Here is its definition.

Vacuum permittivity, commonly denoted e0 (pronounced as "epsilon nought" or "epsilon zero") is the value of the absolute dielectric permittivity of classical vacuum. Alternatively may be referred to as the permittivity of free space, the electric constant, or the distributed capacitance of the vacuum.

 It is the capability of an electric field to permeate a vacuum. This constant relates the units for electric charge to mechanical quantities such as length and force.


2.2 Vacuum permeability

Here is its definition.

Vacuum permeability is derived from production of a magnetic field by an electric current or by a moving electric charge and in all other formulas for magnetic-field production in a vacuum. The physical constant u0, (pronounced "mu nought" or "mu zero") is commonly called the vacuum permeability, the permeability of free space, the permeability of vacuum, or the magnetic constant.



Sometimes, the description uses the term free space, rather than vacuum.

3  Conclusion

Maxwell defined the parameters for a vacuum to support the propagation of the interacting electric and magnetic fields.

A medium other than a vacuum cannot enable a field to be created quicker, only slower.

If a medium is defined to support the propagation of light through an apparent vacuum, The parameter will begin with those for a vacuum and then changed to match the reduced efficiency within a vacuum.

page created April, 2022
last change 04/09/2022