The Magic of Invisibility

THE MAGIC OF INVISIBILITY

The magic of invisibility isn’t magic! It’s science. And we can do this science experiment at home!

I love Harry Potter and the idea of the magic of invisibility. But is it really magic? Or is there a science of invisibility?

Okay, since this is a science blog, you know there’s science involved. Physics. Don’t be afraid. We’ll get through it!

I’ve heard people ask, ‘would you rather fly or be invisible?’ Which would you choose?

Louie says that he’s not interested in flying.

CLOAKING TECHNOLOGY aka INVISIBILITY

I disagree with Louie. I think it’s too tough to choose! Invisibility may be closer than we think! Researchers are working on exactly that. They’ve had success on a small scale with advances in cloaking technology!

Invisibility does seem safer than using makeshift wings. Just ask Icarus! So I looked into advances in cloaking. And in the process, I did a science experiment at home. One that you can recreate!

I re-created an experiment done by the University of Rochester. The experiment uses four lenses, arranged in a way to bend the light–sort of like a doughnut so that when you put an object between two of the lenses, it disappears!

BENDING LIGHT EXPERIMENT

For an object, person, for anything to be seen, light waves must come in contact with it. If a room is dark enough, you can’t see at all. (Once I walked right into the bedroom door, thinking it was open. No bruises, but it proves the point!)

Here’s a look at the set up.  Yes, that’s a ping pong table! I needed a long, flat surface. And a way to keep our boxer, Louie from helping too much!

THE MAGIC OF INVISIBILITY

In the photo below, the pencil is not seen between the two lenses! That’s because the visible light waves bend around the pencil. We are essentially bending light! Think of a prism and how it can bend light. (Prisms also separate the visible light waves into their individual wavelengths or colors, but that’s another topic)

The formula is below courtesy of the University of Rochester.

INSTRUCTIONS TO CREATE THE MAGIC OF INVISIBILITY AT HOME

1. Purchase 2 sets of 2 lenses with different focal lengths f₁ and f₂ (4 lenses total, 2 with f₁ focal length, and 2 with f₂ focal length)
2. Separate the first 2 lenses by the sum of their focal lengths (So f₁ lens is the first lens, f₂ is the 2nd lens, and they are separated by t₁= f₁+ f₂).
3. Do the same in Step 2 for the other two lenses.
4. Separate the two sets by t₂=2 f₂ (f₁+ f₂) / (f₁— f₂) apart, so that the two f₂ lenses are t₂ apart.

I can provide more details or cheer you on if you want to try it. Contact me.

Which would you choose? Flying or invisibility?