Wave cancellation

Soldato
Joined
12 Oct 2003
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When two similar waves of the electromagnetism cancel each other out, where does the energy go?

If the energy is still there and they're slightly out of phase, could you essentially project them at a distance and make them appear as if out of nowhere?

Im just wondering because I've been watching lots of physics videos in recent weeks, think I missed or didn't quite understand this particular area. :p
 
the key word is interfere, be it constuctivly or destructivly

with the out of phase thing it's not possible, as they will always appear from an emitter or reflector, light is a good example because light is an electromagnetic wave aswell

as for the canceling out thing, it's a bit difficult to explain. but when two waves destructivly interfere they are technicly still there and still travelling. but because at the same period in the wave the energy signature has the same amplitude but is just inverse so there is no resultant signal or energy to be detected... or something like that
 
its interesting

my prof (or it might have been me, can't remember) proposed a problem ages ago where two photons are travelling towards each other but they are out of phase. As soon as they hit each other they destrustively interfere - what happens then? doe it disappear? in which case where does the energy go? or do they continue in opposite directions after they have passed each other? - in which case, what is happening at the point they meet? as they effectively don't exist at that point - do they disappear and then reappear? but then how is that possible?
i don't know the answer
 
aardvark said:
its interesting

my prof (or it might have been me, can't remember) proposed a problem ages ago where two photons are travelling towards each other but they are out of phase. As soon as they hit each other they destrustively interfere - what happens then? doe it disappear? in which case where does the energy go? or do they continue in opposite directions after they have passed each other? - in which case, what is happening at the point they meet? as they effectively don't exist at that point - do they disappear and then reappear? but then how is that possible?
i don't know the answer
iirc Waves can't "hit" each other so due to the wave-particle duality they will interact as particles if they physically hit each other and aren't interacting as waves.
 
The key thing for waves canceling is that is is a net effect. On some plank length (very small scale) the energy would be there, as since the waves would pass and "go through each other" and continue on their opposite paths. This coming together does not destroy the photon or sometimes called information. If you think of waves on the sea or sound the pressures they do cancel each other out.
 
Kreeeee said:
iirc Waves can't "hit" each other so due to the wave-particle duality they will interact as particles if they physically hit each other and aren't interacting as waves.


but they can 'hit' each other - photons belong to the class of 'particles' that can occupy the same point in space (fermions or bosons - i can't remember which)
 
aardvark said:
but they can 'hit' each other - photons belong to the class of 'particles' that can occupy the same point in space (fermions or bosons - i can't remember which)

photon = boson :)

electron, proton, neutron = fermion
 
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