Sometimes festive greetings come in small packages. Very, very small packages. The National Physical Laboratory, the UK's national measurement institute, has created what it calls the world's smallest Christmas card, and it requires a very strong microscope to see it.
This particular card isn't printed on paper. "The card is made from platinum-coated silicon nitride, usually used in electronics, and both the design on the front and the message inside were carved out by a focused ion beam -- a jet of charged particles," says the NPL.
The card has "Seasons Greetings" on the front beneath an image of a snowman. The inside reads, "Seasons Greetings From NPL." It's a mere 20 micrometers tall, which translates to about 0.00079 inches. You could fit 200 million of the mini cards in one postage stamp.
This is a fun application of some cutting-edge technology. "We are using the tools that created the card to accurately measure the thickness of extremely small features in materials, helping to unlock new battery and semiconductor technologies," says NPL research fellow David Cox, one of the card's creators.
The card joins an impressive lineup of impossibly tiny things we've seen in the past, including a, , and even a etched onto a human hair.