Cueva de los Cristales (Cave of the Crystals) in Mexico is a cave 300 meter underground containing some of the largest natural crystals. To give you an idea of how big these crystals are, the largest one found to date is 11m long, 4m wide, and weight 55 tons.

The crystals are made of selenite, a type of gypsum, and are translucent. At first, geologists did not understand how cyrstals can grow to be so big, but they figured it out and published in the journal Geology. By studying tiny pockets of fluid trapped inside, the scientists figured that the crystals thrived because they were submerged in mineral-rich water with a very narrow, stable temperature range of around 54°C.

And now the BBC’s Professor Iain Stewart has gone exploring, producing amazing footage. Here is a preview of the show.

The cave was discovered by two miners excavating a new tunnel in the Naica mine in the Chihuahuan Desert in Mexico for the Industrias Peñoles company in 2000. More photos from National Geographic.

One of the best water videos I’ve seen in a while: a super-slow motion video of a 12-foot monster barrel wave, the first time ever this kind of video has been taken.

The first video below is the full story of how it was filmed, which is very interesting and has the footage at the end. If you’re impatient and want to see just the video, the second video is 1-minute long and shows you just the wave video.

Full Video

Summary Video

WiTricity is an MIT spin-off company that is commercializing wireless transfer of electricity. The technology is an implementation of a very old idea: if you think of an electricy transformer having two coils inside it, you will realize that power is transfered from one coil to the other, but without them touching each other. The WiTricity system is a lot like that, but instead of having the coils millimeters apart, they are a few meters apart.

What can it do? A lot. The image below shows the demonstration of their wireless electrical power transfer. The coil on the left is the source coil and it creates a magnetic field that the coil on the right is fine-tuned to capture. The transfer of power from the left coil to the right coil is sufficient to power a 60-Watt light bulb which you can see hanging off the right coil.

WiTricty demo of lighting a 60W bulb at a distance of 2m. The induction coils are hung from the ceiling, and the 60W light bulb is attached to the coil on the right.

Wireless Power Transfer via Strongly Coupled Magnetic Resonances, Science Kurs et al. 317 (5834): 83, supplemental info.

Although powering a light bulb is useful, WiTricity’s system can do more. The 10-minute video below explains the technology and then shows the system powering an LCD television and mobile phones. All without wires!

There is more info in the Science magazine paper the MIT published and its supplementary information. There is also the BBC coverage video, and of course, WiTricity’s website.

A simple trick to cut a bottle cleanly to give a straight rim.

Be careful with the fire bit!

Do chimpansees ask for help? A very simple question about complex behavior.

The short answer is yes they do ask for help, but not from other chimps! Researchers in Japan hid food under a stone and taught the chimps that they can move the stone to get to the food. Then they replaced the stone with a much heavier one, a stone that one chimp cannot move on its own and must seek help to move. Initially, they didn’t know how to get to the food, but eventually, they learned to ask for help from a researcher standing nearby. It would look at the researcher’s face, vocalize some sounds, grab its hand and make it hold the stone’s handles! However, it would not do the same with a chimp.

Anyway, there is a lot more to this as the video below shows. If you’re interested, the paper is titled Chimpanzees (Pan troglodytes) learn to act with other individuals in a cooperative task.

A Rubens’ tube, or Standing wave flame tube, is a physics experiment that allows you to visualize sound waves. Much like the visualizer in a music player, it uses a propane flame that responds to the music.

The arrangement is simple: a tube is perforated along one side with holes. One end of the tube is attached to a propane gas source. The other end is sealed with a sound speaker. The propane is turned one and lit forming a line of flame along the edge of the tube. Then the fun begins.

The videos below are some cool examples of what can be done with Rubens tubes.

More info:

• Sound Flames: Rubens Tube

The cold weather in the 2008/2009 winter shows no sign of letting up. The snow in the UK has gotten a lot press coverage, and on Twitter, the #uksnow hashtag has been very popular in the past few days.

To give you a perspective of just how covered we are in snow, check out this image from 7 January 2009 from NASA’s Terra satellite. Very luckily, the clouds parted across most of the British Isles to give the camera a good shot of the whole scene:

Image credit: NASA/GSFC, MODIS Rapid Response.

Of course, the UK is pretty lucky because elsewhere in Europe and Russia, the cold is deadly. The image below shows the temperature difference between the average temperatue and the current temperature. That is, it doesn’t show the actual temperature, but it shows how much off the historic average it is. This is called the land surface anomaly. The image was take in December 2009:

Image showing the difference between the historic average temperature and the current temperature. White means little difference, blue means colder (the darker blue the lower the temperature compared to history) and red means warmer (the darker the higher the temperature compard to history).

Image credit: Jesse Allen, using data provided courtesy of the MODIS Land Group.

Oh yes, it’s cold.

The good people at Periodic Videos have a very cool demonstration of how to make a silver mirror. It’s the same chemistry that is used to make mirrors for homes and Thermos bottles.

The chemistry is this: start with silver nitrate (AgNO₃) salt solution in water. This is made more reactive by adding ammonia solution, which contains hydroxide ions that react to make a precipitate of silver hydroxide (AgOH) which turns the solution brown. More ammonia is added to make silver diamine ions ([Ag(NH₃)₂]⁺, an aqueous diamminesilver(I) complex) which makes the solution clear again. This final solution is added to the glass with some sugar (like you add to coffee or tea) and heated to 70°C for a short while. The reaction produces solid silver which coats the glass and makes a mirror.

The clear solution of silver diamine is called Tollens’ reagent, named after the German chemist Bernhard Christian Gottfried Tollens.

Interesting readings for you:

• Graduate School in the Humanities: Just Don’t Go.
• 25 Awesome Virtual Learning Experiences Online.
• Relative Prices Of Different Liquids.
• Pictures of electricity.

This video is an amazing slowing down of a water droplet hitting a water surface. The droplet actually bounces, several times, as it progressesively coalesces (merges) with the water surface.