Watch YouTube user Xraise Cornell create a homemade horizontal vortex ring generator. When a small burst of air is released into a toroidal or poloidal vortex — essentially a spinning donut of water — it shapes the air into its own ring along the water’s trajectory, creating a vortex ring or a bubble ring.

While we have not made this invention (yet), it looks like a lot of fun. Or of course, with a lot of practice, you could try to make them with no materials at all, just like the dolphins do. Just remember to always be safe. Adult supervision is recommended when using tools or trying experiments underwater.

Or if you want to stay dry, try making a homemade vortex cannon with a tightly closed box with a narrow round hole at the end. Watch!

Above, A Basic Demonstration of Optical Cloaking. Cloaking is a term for hiding an object from view at specific frequencies, but evidently one can cloak things DIY-style with four mirrors and their precise placement.

So before reading further, how is the illusion above happening? Any guesses?

Professor of Physics at the University of Rochester John Howell and his 14 year-old son Benjamin built three uni-directional optical cloaking devices with everyday materials. For around $150, they put together “one made of Plexiglass and water, another of inexpensive lenses, and a third constructed using ordinary mirrors.” The video demonstration above shows one of the devices and two of his sons… sometimes. 

What might this small feat of optical engineering be used for? Since it’s uni-directional it has limitations, but in theory, it could hide satellites orbiting Earth. You can read more about how Professor Howell’s devices work in the videos notes, here on arXiv.org, or on MIT Technology Review.

There are also a few more videos with mirrors in the archives.

Thanks, @AmebaCuriosa.

Two college student designers (Luke Greenway and Laura D’Asaro), 27 volunteers, seven hours of work, five attempts, and 2,131 books mixed together at the Seattle Public Library to create the longest book domino chain in the world. The library used the new world record to celebrate and promote their 2013 Summer Reading Program.

There are many, many more chain reactions, world records, and books in the archives, including this stop motion fun: The Joy of Books.

via Daily of the Day.

In the same way that we use reusable metal water bottles and sippy cups for kids on-the-go, the team at Keep Cup is promoting reusable coffee containers for adults on-the-go in this promo video called Salute the Reuser.

This is a wonderful idea no matter what container you keep with you. Our family recently started taking our insulated Klean Kanteens to coffee shops instead of using disposable paper cups and plastic lids, so this video definitely speaks to us.

Related sustainability: In.gredients’ package free store, The Landfill, and one of our absolute favorites, Joe Smith demonstrates how to use a paper towel.

via Doobybrain.

Bodypercussion, choreographed and performed by Santi Serratosa and Mariona Castells, to the song Not Worthy by Jack Savoretti.

A fun DIY, we were able to mimic a few sections of the choreography ourselves. It reminded us of this viral hit from a few years ago (that we would have needed a lot more practice to keep up with) — We No Speak Americano by Suzanne Cleary & Peter Harding:

The great thing about an activity like this is that you can always create your own dance moves to your favorite song. (And if you do, tell us about it!)

Get inspired by more performances, songs, and more dance videos in the archives, as well as this music video favorite of ours: Let’s Go by Matt & Kim.

Thanks, @immapunti.