Keith Dysart wrote:
I do use the view that the energy is trapped. The difficulty is: What
is the mechanism that traps the energy?

Photonic energy cannot be trapped in a homogeneous medium.
It is simply impossible to accomplish that feat without
any discontinuities to cause reflections.

The energy components are not trapped. There is exactly the
amount of energy in the line as required to support the
forward wave and reflected wave. The concept of trapped
energy is an illusion, an artificial shuffling of the
component energy. Modulation will reveal exactly
what is happening. I like TV ghosting examples.

Standing light waves can happen in free space. There is no
mechanism that traps the energy because there is no trapped
energy.

And yet, when I look at pulses, where the energy is clearly visible,
I develop some sympathy for Cecil's position.

He also concluded some time back that two waves which
collide had to reverse direction in order to conserve power, energy,
momentum, or something. Energy in the system is conserved; but nowhere
is it written that each wave has to have individually conserved energy.

For the record, what Roy said above is a false statement.
Canceled waves are necessarily moving in the same direction
at the same speed. It is impossible for them to collide.

Roy cannot produce even a single example where I said
colliding waves reverse direction in a homogeneous medium.

And it is certainly written that *all* energy, individual or
not, must be conserved. Not only must the energy in each
wave be conserved, the momentum in that wave must also
be conserved.

Numerologically it surely does appear that one can superpose powers
since 200+(-50) is 150.

Superposition requires a phase angle and power has no phase
angle so superposition cannot apply.

However, in the complete absence of interference, powers
can certainly be added. In the irradiance equation, if the
interference term is zero, the sum of two powers is simply
P1 + P2. It happens when the two waves are normal to each
other.
--
73, Cecil http://www.w5dxp.com