Negative index metamaterials

Negative index metamaterials are like special materials that can do some tricks with light. Normally light moves in the same direction as it travels, but with negative index metamaterials it can go backwards, or even sideways!

It's like if you were playing with a ball and normally it goes straight when you throw it, but with negative index metamaterials it can change its direction or even come back to you when you throw it.

The reason these materials can do this is because they are made up of tiny things called "meta-atoms" that are smaller than the wavelength of light. These meta-atoms act like tiny antennas that can manipulate the light in different ways.

So basically, negative index metamaterials are fancy materials that can play some cool tricks with light because of their tiny "meta-atoms."