Animation reveals the world's hidden equations

MacGregor Campbell, contributor

Although they don't actually exist in the physical world, our most powerful tools could be mathematical equations. They underlie much of modern technology, from radio to power generation, to photo compression and electronic musical instruments.

In our latest animated explainer, we look at how the wave equation, Maxwell's equations and the Fourier transform came to rule the modern world. To find out more, read our full-length feature, Seven equations that rule your world.

For more math-related viewing check out our archive of One-Minute-Math
videos, or watch our previous animations to find out, for example, if supersymmetry could explain everything or why there is no such thing as empty space

http://www.newscientist.com/.

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Pulsating coral puffs up to escape sandy burial

Caitlin Stier, video intern

Not all corals are couch potatoes. When faced with live burial, this nomadic mushroom variety can swell up to cast off sediment, reaching up to five times its resting size.

The time-lapse, captured in an aquarium by ecologist Pim Bongaerts from the University of Queensland, shows a coral huffing in controlled pulses under a pile of sand. The tentacles move in unison, likely due to contraction within the tissue. A few hours later, it unearths itself from the rubble.

"I was completely blown away," says Bongaerts. "I had no idea corals were able to perform such controlled movements. People always tend to think of corals as rocks or plants, however these videos clearly show that they are living animals with their own interesting behaviour."

Although scientists knew that corals could unbury themselves, this key survival tactic has seldom been documented. Bongaerts suspects that pulses are created as polyps suck in and expel water, but he plans to further investigate the feat. Along with his collaborator Bert Hoeksema of the Netherlands Centre for Biodiversity Naturalis, he also hopes to document more of these corals' secrets, such as their motility along the seabed and aggression between corals.

If you enjoyed this video, check out more undersea wonders like Antarctic mega-crabs and laser-illuminated jellyfish.

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Friday Illusion: Mind-bending chessboard seems to tilt

Caitlin Stier, video intern

 

You may want to get your rulers out: although this oversized chessboard seems to slant when animated, its rows and columns are always perfectly parallel.

The animation, developed by Sinji Nonaka, tricks your brain when alternating rows are shifted horizontally or vertically, skewing the grid pattern. The unusual effect was discovered by a member of vision researcher Richard Gregory's team as he looked at the brick tiling of a Bristol café in the 1970s. Gregory was inspired to recreate the design for a party organised by the BBC TV programme Tomorrow's World. But during the process he made a key discovery: the illusion was dependent on the shade of the mortar between the rows.

To test the effect, Gregory worked with Priscilla Heard, now at the University of the West of England, to develop a customisable version of the wall using reflective surfaces, adjustable lights and moving tiles. By varying the brightness of the mortar, they found that it had to fall in between the contrast of the black and white tiles for the effect to occur. A thinner lining also produced steeper slopes.  

But in addition to the brightness of gaps between rows, the offset of the chessboard is also responsible for the effect. The shift causes like-shaded squares to overlap which affects the perceived brightness of the tiny space in between. The gap appears to be lighter for two dark squares and darker where white ones meet, causing a striation that's processed by our brain as a single line indicating slope. 

If you enjoyed this illusion, check out another trippy chessboard or watch shifting lines create a phantom spin.

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Killer T-cell surrounds cancer in targeted attack

Caitlin Stier, video intern

On a mission to search and destroy cancer, an immune system T-cell launches its attack on a tumour cell in a new time-lapse movie. Captured by graduate student Alex Ritter, a member of Gillian Griffiths' team at the University of Cambridge, the video reveals how the T-cell's centrosome, shown in red, is used to hone in on a cancer cell so that it can accurately transfer toxic enzymes.

Typically the centrosome acts as a transit hub, sending goods out to cells through a protein scaffolding. But in this case, it plays a much more active role. "Killer T-cells are incredibly potent," says Griffiths. "You have to focus that secretion incredibly accurately and we found that the centrosome goes right up to the membrane at the point where the secretion is delivered to make that happen."

The team is studying this process by looking at patients with genetic disorders that disrupt centrosome function. The work could help researchers identify ways to exploit our natural immunity to target cancer, as well as to alleviate immune disorders where errant T-cells destroy healthy tissue.

If you liked this video, watch malaria invade a blood cell or see the world's fastest cells race. 

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