Saturday, March 21, 2015

Electromagnetic Reality

The production and reception of electromagnetic waves is a scientific phenomenon of crucial importance. What is the wonder of electromagnetic waves? We are immersed in them in multiple ways every moment of our existence. For example, we experience visible light and infrared radiation in the form of life sustaining heat each day of our lives. These energy forms arrive by electromagnetic radiation.  

Several hundred years ago scientists did not have a good understanding of electricity and magnetism. For hundreds, even thousands of years we have observational records of simple static electric and magnetic phenomena. Landmark discoveries proliferated beginning with the onset of the Scientific Revolution in the last four centuries. Scientists such as Robert Boyle (1627-1691) brought empiricism to bear on the knowledge of their time. Famously, Benjamin Franklin (1706-1790) performed the hazardous kite experiment. He termed electricity an”imponderable fluid” pervading everything. Later, other famous scientists such as Farraday, Galvani, Volta, Ampère, and Ohm weighed in with discoveries for which units of electrical measurement are currently named.

During the 18th century a few scientists suggested the relationship between electricity and magnetism. Hans Christian Oersted (1777-1851) and Michael Farraday (1791-1867) were most prominent in this discovery. But it remained for a giant to emerge in order to perfect one of the most important scientific theories of all time. James Clerk Maxwell (1831-1879) possessed deep Christian faith. No less a scientific genius than Albert Einstein pronounced Maxwell’s work “the most profound and the most fruitful that physics has experienced since the time of Newton.” Our previous post puts him in perspective:

Information on electricity and magnetism must have reference to atoms, discrete particles demonstrated empirically about two centuries ago. Scientists more recently discovered the subatomic, fundamental particles which comprise atoms: electrons in 1897, protons in 1917, and neutrons in 1932. Many older citizens are surprised how recently these discoveries have been made. Most of their parents were unaware of the above-mentioned subatomic particles early in the 20th century. Atoms of ordinary matter generate the bath of electromagnetic radiation in which we are embedded. The spectrum of electromagnetic radiation is composed of radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma rays.

Ordinary atoms are composed of electrons with their negative electrical charges, protons with their positive electrical charges, and neutrons with no electrical charge. Atoms of ordinary matter are constantly vibrating with kinetic (motion) energy. Electrons are constantly moving in a swarm surrounding the nucleus. This means their positive and negative electrical charges are always moving. When electric charges are accelerated (moving), they generate waves of electric or magnetic fields.

Returning to James Clerk Maxwell’s genius, he discovered that visible light is an undulation of electric and magnetic waves traveling in phase, oscillating together at right angles through space. When I taught early lessons on the electromagnetic spectrum (EMS) to my class, we first demonstrated the effects of electricity traveling through a copper wire on a compass needle a short distance away. Then we showed that the magnetic field surrounding a magnet generates electricity in a coiled wire when passed through the coil. Electricity and magnetism were related, students concluded. We defined light as an electromagnetic wave which had electric as well as magnetic components. It was a useful, albeit not a highly technical concept.

Maxwell described electromagnetic wavelengths as the distance between the pulses of electric and/or magnetic energy. Pulses of electromagnetic waves are called photons and act like particles. He taught that visible light is electromagnetic wave energy and predicted that there should be many others discovered or artificially generated in future years. He was correct. His mathematical formulas are difficult for laypeople to understand, but scientists of every stripe have defined the work of Maxwell as the work of an inspired genius.

Since Maxwell’s discoveries, scientists have discovered an overpowering yet simple truth about the EMS. All electromagnetic waves of any wavelength (radio, microwave, infrared, light, ultraviolet, x-rays and gamma) are produced by atoms. Moving electrical charges or moving electric/magnetic fields are continually produced by atoms. We know, of course, that atoms are everywhere in our environment. Many electromagnetic waves are produced naturally; some are produced artificially by man; others are produced either way.

Contemplate how our lives are sustained by moving electrical charges in the atoms of ordinary elements. They generate multiple types of electromagnetic waves each moment. We must also contemplate the gifts of discovery of many scientists who came before us. We are indebted to their discoveries. 

Hundreds of scientists have focused our attention on the wonders of electromagnetic reality. James Clerk Maxwell’s profound Christian faith inspired him to proclaim “…the ordered uniformity rather than the peculiarity and complexity of nature, as signs of the Creator.”