SOUND & LIGHT

 Did you ever hear an airplane break the "sound barrier?"  At the point where an airplane exceeds the speed of sound it causes a "sonic boom."   When I grew up in the 1940's and 50's, it was becoming commonplace and then laws were passed to prohibit planes from doing that over populated areas.  It was quite a sound.  For example, the cruising speed of a Boeing 737 is 583 mph. The speed of sound waves is about 770 mph.  Military jet planes can go that fast but usually refrain from doing it.

How about the crack of a bullwhip?  The loud "crack" sound is the result of the tip of the whip traveling greater than the speed of sound.  

Did you see some lightening last week?   You know we see the lightening before we hear the sound.  Of course the speed of light is much faster than sound -  the speed of light being about 670,000,000 mph.  

Have you heard someone talking about "light years" and not know exactly what that was except that you knew it was long.  Astronomers use "light years" as a measure of distance.  One "light year" is the distance light would travel in one Earth year.  That would be about 6,000,000,000,000 (that's trillion) miles.  

Sorry!  I can see your eyes glazing over about now.  You're wondering what the point of all this is.  Well, I forget; I must have been ruing the plight of the aged.  Old age callously makes us aware that our senses, as well as our mental and physical acuity, are declining.  One day you realize your eyesight is not what it used to be.  The next, that your hearing is failing.  The next, that you're not as bright as you once were.  Then, sadly, your athletic ability is gone.

Light and sound are amazing.  Good health, mental and physical, are gifts.  Remember to say thanks before they are all gone.  

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