Photon Propulsion.

[YT2095]

I was experimenting this morning with different color filters for one of my camera flashes and noticed a Very odd phenomenon!

the Blue and Red filters (especially) made a slight Ticking sound and I felt a little "Kick" in the filter frame each time the flash went off.

I showed this to my wife and she confirmed I wasn`t imagining it.

I set up a small sheet of blue acetate on a string suspended off a retort stand and tried again, it Moved the filter!

I experimented with black film and tinfoil, both gave a "kick" but the black film was the strongest by far.

and after several shots the film was getting quite hot, enough to leave an impression on the film.

 

my conclusion is that the "kick" is actually a small explosion of sorts, created by the air directly next to the colored film expanding nearly instantly because of the heat generated by the light.

 

this reminded me of something I`d seen on a TV documentary a few years ago where Lasers were used to propel craft, here:

 

http://en.wikipedia.org/wiki/Lightcraft

http://en.wikipedia.org/wiki/Laser_propulsion

 

so there you have it, you can Now demonstrate this exact principal Yourself at home!

 

be aware that looking directly at a camera flash at close range is extremely likely to cause eye damage, some of which could be permanent!

also note that the flash used isn`t the sort found on cheap disposable cams of snapshot cams, I used a Cobra Auto 150s.

I have no idea if the smaller flashes in these other cams will work as well but by all means try it!

YMMV.

[insane_alien]

is there any chance it could be an expansion of the filter causing it to distort? it could explain how the tinfoil doesn't kick so much as it absorbs very little light. while a filter will absorb a lot of light, this could cause it to expand and structural stresses cause it to momentarily pop out of its normal shape displacing some air along with it.

 

although the expanding air sounds equally plausible. just looking for a little debate and discussion here.

 

when you do this experiment does it appear that the filter is bulging anywhere for a breif time?

[YT2095]

a Very good question and one I can answer definitively, I just did another experiment to test your idea by making a cone of black film sellotape sealed and used blue-tack to fix this over the flash area making it airtight, then I cut the tip off the cone.

 

the idea being that IF it`s air expanding, I`ll get a blast of this exit the cone tip.

 

I can launch a small piece id paper into the air with this air blast, knock the ash off a cigarette and make a candle flame flicker.

 

it would seem that it IS air

 

Do NOT put this cone into your ear to test it! it`s Very loud.

[Klaynos]

Flashes produce alot of hight (enough so if you put your hand infront you can burn them), as you're doing alot of absorption here my first guess would be that this is caused my thermal expansion not due to photon momentum, there's an easy way to find out though put a mirror there instead you should get a more seiouse kick then if it's photon pressure.

[YT2095]

I just tried Aluminium tape (very shiny) and yes there is a stronger "kick" more so than the crumpled bit of foil I tried with earlier.

however I don`t think it`s Photon pressure as you suggest, I still think it`s air being heated instantly close to the surface of the target creating a sort of explosion.

although there will be a little bit of pressure directly from photons, I don`t think this is the cause.

 

really I would need to do this in a Vacuum chamber to know for sure, and I`m fresh out of those.

[ydoaPs]

really I would need to do this in a Vacuum chamber to know for sure, and I`m fresh out of those.

 

Then make one.