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V. E. “Bill” Haloulakos,  Aerospace Science Consultant/Professor; AIAA National Distinguished Lecturer and Legacy Member; Distinguished Engineering Educator Award Winner

* Sound and light waves allow us to talk to and see each other

* Ultrasound and radiation waves have many applications in medicine

* Electromagnetic waves have given us radio, television, cordless and cell phones and all the gadgetry and allows us to text to and follow each other


All or most of us have either given or received the advice of “don’t make waves”. What this means is “don’t create a disturbance” because in physics the definition of a wave is “a disturbance that once created it travels in its own way and unique speed and cannot be altered”. How many of us wish if we could only take back something that we said…

There are many types of waves. There are the sound waves, which allows us to communicate with each other. As we speak we create a disturbance that travels through the air at the speed of sound (345 meters per second (m/s)) to the ears of all around us. Then we have water waves that we see in the rivers, ponds and the sea. And nature is full of electromagnetic waves (EM), visible light being part of the EM wave family its only special characteristic being that it excites our retina and allow us to see things. Other wise light is of the same nature as x-rays that destroy our retina. One peculiarity of all the different waves is that they are described by the same mathematical equation, very appropriately called “the wave equation”, a subject upon which we shall not elaborate here, but we shall note that the only difference is their speed of propagation (travel). As noted above sound waves travel at 345 m/s whereas EM waves travel at the speed of light or 300,000 kilometers per second (km/s) (186,000 miles/s).

It travels seven and a half times around the equator in one second!

We noted above that our voice-generated waves travel through the air. It is known that sound waves cannot travel through vacuum. There is a simple experiment in basic high school and freshman college physics that proves that. An electric bell is enclosed in a glass dome and the set up is connected to a vacuum pump. The bell is rang and we can hear it. Then the air from the glass dome is evacuated and then the bell is rang again. We can see the hammer striking the bell but we cannot hear it. So, the conclusion is that sound waves do not travel through vacuum. We should note that while we can see the hammer striking the bell no statement is ever made that this means that light waves do

travel through vacuum, otherwise the glass dome would go dark. This is probably so because it is an experiment about sound waves. However for a long time this was extrapolated to mean that all waves do not travel through vacuum. This included the light waves. So, as James Clerk Maxwell discovered the EM wave in the 1860s and conclusively showed light to be an EM wave it was immediately suggested that since we could see the sun then space cannot be a vacuum but it is filled with some kind of medium through which sunlight must travel. This medium was tagged as ether a substance never detected or otherwise identified.

As the world consumed the idea of EM waves, a special detail was uncovered with the mathematical wave equation, which said that depending of whether we viewed waves while standing or moving they should look different. This of course is not so because ocean surface waves look the same and do not depend on whether we observe them while standing or driving along the beach. This detail along with the idea of the ether-filled space were the two factors that made the rise of Einstein possible who provided the correct answers and became a household word in the process.

It is Maxwell’s work, however, that affects our daily lives more so. It has made the creation of large enterprises such as Apple, Google, Facebook, etc. possible and has given us our mobile devises.

So, as you talk or text on your cell phone, think and thank James Clerk Maxwell.


  1. Dr Haloulakos has long been associated with exotic, high-tech research. If you enjoyed this article, you might enjoy his book ROCKET PROPULSION FUNDAMENTALS that provides a series of problem-based examples of computer simulations used in the NERVA (Nuclear Engine Rocket Vehicle Application) program.

    Here is information on his book. ROCKET PROPULSION FUNDAMENTALS AND MISSION ANALYSIS. By Dr V.E. (Bill) Haloulakos. ISBN: 9780100729018

    Can be ordered online at:
    OR by phone: 858-534-4557

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