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Author Topic: What happens when two EM waves collide in space.  (Read 2823 times)

Offline sleeping

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What happens when two EM waves collide in space.
« on: 19/10/2012 09:04:03 »
I understand that photons do not interact in free space. How about two electromagnetic waves in free space. For example, if you have two EM waves with differing frequencies colliding in space, will we get a third EM wave that is modulated by the two waves.

Thanks


 

Offline evan_au

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Re: What happens when two EM waves collide in space.
« Reply #1 on: 19/10/2012 11:09:24 »
There are some non-linear materials which will allow photons to interact in the manner you describe. Optical fibers will do this if the power levels get too high.

In a vacuum, electromagnetic waves will pass through each other.

However, if the photon energy gets high enough (like gamma rays), they can produce a pair of particles (like an electron and a positron) through their interaction.
 

Offline JP

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Re: What happens when two EM waves collide in space.
« Reply #2 on: 19/10/2012 16:22:30 »
However, if the photon energy gets high enough (like gamma rays), they can produce a pair of particles (like an electron and a positron) through their interaction.

Yep!  Photons can't interact because they only interact directly with things with charge.  Photons don't have charge, so they don't interact directly with each other.  However, they can interact with the vacuum because due to weird quantum effects, the vacuum can have a sort-of charge (through virtual particles).  If two photons interact with the vacuum, then through the vacuum they can secondarily interact with each other.
 

Offline sleeping

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Re: What happens when two EM waves collide in space.
« Reply #3 on: 19/10/2012 18:35:57 »
Thanks for the answers.

So, by theory if the 2 EM waves are high energy gamma rays collide, a third EM should appear. This 3rd EM wave would be modulated or have component freq of the previous two EM waves.
 

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Re: What happens when two EM waves collide in space.
« Reply #3 on: 19/10/2012 18:35:57 »

 

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