Invisible Fire Expiriment

This post is a followup from a previous post on invisibility experiments that can be done at home ( In this post I am elaborating on the concept of using heat to bend light. Heat bends light because it excites air molecules that the light is traveling through. The excited air molecules move differently than they would normally and thus conduct light differently as well. In this experiment you will be able to see exactly how much light is actually distorted by the air molecules. Although this experiment is not necessarily useful for hiding an object completely it does provide insight into how a device could mask its existence by bending light. Again, extreme heat is not the safest way to bend light but it dose seem at the moment to provide an excellent mechanism for doing so. The key for making this experiment practical for making something invisible would be to find a way to agitate the air molecules without using something as dangerous as extreme heat.

(Click on images to view them larger.)

To begin you will need these items:
(metal barrel, drill, 4 bricks, newspaper, two different sized punches and a sledge hammer)

Use the drill to make holes in the side of the barrel. These will be necessarily for the fire to get oxygen so that it will continue to burn. Drill holes about a hands width apart.

After holes are drilled use the sledge hammer and the smaller punch to widen the holes enough to fit the larger punch. Use the larger pinch to widen them further. Each hole should be about an inch in diameter.

Holes drilled in metal barrel.

Stand the barrel on the bricks to keep it off the ground.

Crumple newspapers and add some branches to the barrel to burn.

Light a single piece of newspaper and drop it to the bottom of the barrel so that the rest of the paper ignites.

Feed the fire with branches until a thick bed of coals accumulates. You should start to be able to see ripples in the air over the barrel.

Have a fellow experimenter stand on the opposite side of the barrel from you and hold a grid similar to the one in the picture. The lines on the grid should be clearly visible and drawn with a ruler.

(click on image to view it larger)
Behind barrel: left, no barrel: right
The results are easy to see. The grid healed behind the heated barrel shows a great amount of distortion due to the light being affected by the heat. Besides giving insight on how invisibility devices could potentially operate this experiment also demonstrates exactly how mirages work (as well as getting rid of a lot of debris from your yard).

Please note that if you attempt this you do so at your own risk. Fire and the materials that touch it get extremely hot and can result in serious injury. The author of this article has no responsibility if you get hurt.