Is Teraherz Radiation New?
Most recent answer: 01/19/2014
- Nehemiah (age 23)
Indiana
That question raises the important differences between rough verbal names that we give things and the more precise mathematical descriptions at the core of physics. Teraherz electromagnetic waves were always understood, starting from Maxwell's discovery (~1864) of the equations describing electromagnetism. All the different frequencies of those waves are described by exactly the same equations and follow the same patterns. The different names you mention ("radio waves, microwaves, infrared, visible, ultra violent, x-rays, and gamma rays") are just rough divisions of the full spectrum into different ranges, and have no particular deep meaning. The teraherz range was included as part of the far infrared in the traditional naming regime. Now that some convenient teraherz sources are available, and some interesting applications, people have started using a special name for that range rather than lumping it in a bigger category.
The same principle applies to sound. The possible frequencies are continuous, with no missing gaps. Exactly where people draw the lines between the different names chosen doesn't affect the behavior of the waves. If "ultrasound" means sound at frequencies higher than audible, it would have started at around 20kHz when I was young. Now it would be more like 12kHz. My ears have changed, but the sound waves haven't.
Mike W.
(published on 01/19/2014)