# Do photons collide with each other?
**URL:** https://boards.straightdope.com/t/do-photons-collide-with-each-other/99371
**Category:** Factual Questions
**Created:** [March 21, 2002, 5:49pm UTC](https://boards.straightdope.com/t/do-photons-collide-with-each-other/99371 "2002-03-21T17:49:50Z")
**Posts on this page:** 3
**Page:** 2
### Author:  [@scotth](https://boards.straightdope.com/u/scotth)
#### Post date: [March 21, 2002, 9:30pm UTC](https://boards.straightdope.com/t/do-photons-collide-with-each-other/99371/21 "2002-03-21T21:30:06Z")
> [@](#):
>
> \*Originally posted by Whack-a-Mole \*
> \*\*
>
> Assume I manage this experiment with a single laser beam split (as both you and **Cal** mention it would be far easier this way) and manage to get them to destructively interfere at a given focal point. If I place a piece of paper at that focal point will the laser still burn through it (assume the lasers have more than sufficient power to put a hole in paper or whatever material we place there and assume you are capable of the precision necessary to perform this experiment)?
>
> What I am getting at here with the energy ‘hiding’ is how much energy is actually present where the two waves cancel each other. Is it all still really there such that I still zap whatever is there or do they really zero out?
>
> Sorry for the hijack but I’m curious. \*\*
There is zero energy where the waves are cancelling. Putting a target up where the beams are perfectly destructively cancelling would show nothing. There would be no illumination, and certainly no damage.
BTW, getting a laser that will punch a hole in something even as slight as a piece of paper isn’t cheap.
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### Author:  [@Ring](https://boards.straightdope.com/u/Ring)
#### Post date: [March 22, 2002, 1:04am UTC](https://boards.straightdope.com/t/do-photons-collide-with-each-other/99371/22 "2002-03-22T01:04:39Z")
> [@](#):
>
> \*Originally posted by Whack-a-Mole \*
> \*\*
>
> What I am getting at here with the energy ‘hiding’ is how much energy is actually present where the two waves cancel each other. Is it all still really there such that I still zap whatever is there or do they really zero out?
> \*\*
It’s all still really there. For any conceivable laser and lens combination you are unable to get destructive interference without an equal amount of constructive interference.
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### Author:  [@Ring](https://boards.straightdope.com/u/Ring)
#### Post date: [March 22, 2002, 1:22am UTC](https://boards.straightdope.com/t/do-photons-collide-with-each-other/99371/23 "2002-03-22T01:22:46Z")
> [@](#):
>
> _Originally posted by Whack-a-Mole \*
> \*\*
> Is it all still really there such that I still zap whatever is there or do they really zero out?_\*
I missed this part. You won’t necessarily zap what’s there, because the constructive interference will probably occur away from the target.
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