The Story of Infrared Discovery

Posted March 18, 2019

Over the past three years I have written many articles concerning infrared and fitness.  Sometimes I am still asked very basic questions such as “what is infrared?”  And, sometimes, well, actually more than just sometimes, I am still looked at with a deer in the headlights expression when I begin to explain “infrared fitness”.

Everyone knows fitness, but not so many know about infrared.  Once explained, however, all are amazed and convinced to give infrared fitness a try. 

The knowledge base is growing with the help of resources like this HOTWORX blog. 

So, in this article, let’s begin the story with the basics and go straight to the definition according to Merriam-Webster.

in·​fra·​red | \ ˌin-frə-ˈred. adjective

Definition of infrared

1: situated outside the visible spectrum at its red end —used of radiation having a wavelength between about 700 nanometers and 1 millimeter 1

The red light waves have the longest wave length of all of the visible light waves.  Infrared is located just beyond the red visible light waves.  Infrared is invisible. 

The origin of the word comes from “infra” which is Latin meaning below and of course the word “red”.  When the two are combined, below+red is “infrared”.  Infrared light waves lie just “below” or after the visible red waves… “below” red and into the non-visible area of light.

In the early 19th century, a German scientist who became a naturalized citizen of the UK discovered the existence of infrared light while experimenting with different colors of the light spectrum as it passed through a prism. 

So, who was this scientist?

He was William Herschel, the son of a German military family.  His father was a military musician and he himself became an accomplished organist and composer.

Sir William Herschel (knighted by the Royal Hanoverian Guelphic Order – German2), who’s original name was Friedrich Wilhelm Herschel, 1738-1822, was a British astronomer born in Germany, and became the “founder of sidereal astronomy for the systematic observation of the heavens. He discovered the planet Uranus, hypothesized that nebulae are composed of stars, and developed a theory of stellar evolution.”3 He was knighted in 1816.

He used thermometers to measure the temperature of the different colors and as a control he placed a thermometer just outside of the red.  He noticed that temperatures increased as he moved thermometers from the violet end of the spectrum to the red end of the spectrum. To his astonishment he inadvertently discovered through the control thermometer that the area with no color beyond red was actually hotter than the area with color.  What he found was what we now know as infrared heat/energy. 4

Herschel concluded after further experimentation that the sun must emit invisible light beyond the visible red.  The European Space Agency’s infrared space observatory (ISO) is now formally named for him… 

“The European Space Agency’s Herschel Space Observatory (formerly called Far Infrared and Sub-millimetre Telescope or FIRST) flew the largest single mirror ever built for a space telescope. At 3.5-metres in diameter the mirror collected long-wavelength radiation from some of the coldest and most distant objects in the Universe. In addition, Herschel was the only space observatory to cover a spectral range from the far infrared to sub-millimetre.”5

As you can see, infrared has an interesting story.  Since its discovery just over 200 years ago, entreprepreneurs have found ways to use it in commercial settings for numerous applications that give modern life more quality. 

One such use of Herschel’s discovery is the HOTWORX invention of the small group infrared fitness sauna.

Now that you know the story of infrared discovery, you might be inspired to find ways to incorporate this gift from the sun into your daily fitness routine.


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Stephen P. Smith, MA

CEO and Creator of the HOTWORX
Former National Collegiate Bodybuilding Champion and Arena Football Player
Certified Professional Trainer