Category Light

An experiment to determine whether the universe is expanding

In the 19th century the German physicist Joseph von Fraunhofer (1787-1826) discovered that the solar spectrum contains a number of dark bands.  Fraunhofer made a detailed study of the wavelengths of these lines and later it was discovered independently by Bunsen and Kirchhoff that each chemical element has a characteristic set of these so called […]

Einstein and Bohr and the nature of reality

Perhaps the most important scientific debate of the 20th Century was that which took place between Niels Bohr and Albert Einstein during the 1930’s and 40’s. At issue was the very nature of reality. By that time Bohr had become convinced that the laws of physics had to be different on the scale of the […]

Shedding some light on the nature of the photon

Visible light is just a small part of a much of a much broader spectrum of electromagnetic radiation, ranging from radio waves at one end through microwaves, visible light and X Rays to gamma rays at the other end of the spectrum. All of these different and seemingly diverse types of radiation are the various […]

Michelson Morley – the most successful failed experiment

Maxwell’s equations showed the link between electricity and magnetism in space.  A changing electric current produced a magnetic field and a changing magnetic field produced an electric current.  These appear to be related through a pair of constants, permeability and permittivity. Permeability and permittivity appeared to be properties of space itself, but as such they […]

James Clerk Maxwell

Can electric charge exist in the absence of a charged particle?

Up until the 1820’s the only magnets that were known were lodestones and magnets made of iron such as compass needles.  Then in 1820 Hans Christian Oersted was conducting a demonstration of the heating of a wire by means of an electric current.  Coincidentally he also planned a demonstration of the effects of magnetism for […]

The Bandwidth of the Photon ?

James Clerk Maxwell was the first person to connect light with other forms of electromagnetic radiation and in so doing he showed that the bandwidth of electromagnetic radiation extends beyond that of just light.   Since then the spectrum has been broadened to include radio waves, microwaves, infra-red, visible light, ultra violet radiation, X-rays and gamma […]