A Simple and Elegant Cloaking Device

By Anupum Pant

In the year 2011, UTD NanoTech unveiled their carbon nanotube invisibility cloak, making us move one more step closer to realizing a piece of magical cloth which fictional characters often use to turn themselves invisible. And then there was a 3D printed invisibility cloak too.

A few researchers at the University of Rochester have now created their own elegant version of an invisibility cloak. It’s, in principle, a fairly simple optical device which uses just four lenses to cloak objects behind it, keeping the image behind it still visible.

In fact, whatever it does, it does it in 3 dimensions. That means, the viewer looking through the device can actually pan to change the viewing angle and can still see the image of the background, undistorted, as if there were no lenses in between, in real-time. And it is probably the first ever cloaking device to be able to do that.

The device has a blind spot (sort of). In a way that It doesn’t cloak anything that lies in the axis of the lens system. The cloaking area is in the shape of a dough nut. Any part of the object that accidentally enters the axis area becomes visible and conceals the background. The device is simple and cheap enough to be easily scaled to cover greater area, as long as lenses of that size can be made. The video explains it better.

via [Quarks to Quasars]

Bizarre Starfish Wasting Syndrome

By Anupum Pant

Up in the Washington state a videographer and also a diver, Laura James noticed a couple of  dead Starfish on the coast one day. The dead bodies looked like something mysterious had happened. There were broken bodies and splats all over the place as if the fish had been zapped by a laser.

Laura videographed some of the tens of thousands of starfish bodies all over the north america’s pacific coast. No one was sure what was actually happening. And then there were reports of these mysterious starfish deaths from all over the west coast of North America.

For some time, only the sunflower starfish were thought to be affected by this. However, on further investigation, it was found that almost 12 different species of starfish were dying mysteriously all over the west coast (and some on the east coast too). When this was confirmed to be an epidemic of some sort, they started calling it the sea star wasting syndrome and notified the scientists.

Ben minor, a western Washington university professor of biology started collecting sea stars at the coast. They found a number of normal sea stars. Later when the search continued a pile of sea star arms and twisted parts of them were found at different places. Some of the live starfish were collected and were studied in the laboratory.

It was confirmed that the starfish which were affected by this epidemic experienced twisting arms and lesions first and then the arms crawled away in different directions, tearing the body of a starfish apart. All of it in under 24 hours. This bizarre disease then left a spill of inside parts of the fish and broken body parts all over the place.

No one knows for sure what causes this bizarre disease among the sea stars.

The Weissenberg Effect

By Anupum Pant

Remember the time we talked about a boiled egg spinning on a pool of milk? If you don’t then it’s good to know that if you do spin a hard-boiled egg on a pool of milk (or any relatively viscous liquid) the milk mysteriously climbs the side of the egg, reaches the equator, and then sprinkles around beautifully. It’s fun to see it happen. This is something similar…

The thing we see today is called the Weissenberg effect and this is how it works.

You take a spinning rod and put it into a solution of liquid polymer (which is usually very viscous). And when you do that, you see that the liquid polymer magically climbs the walls of the rod.

Some liquids reach a little high and never beyond. While others can climb up really high. The difference in heights to which different liquids can climb to is demonstrated in the following video very clearly. The three liquids used in it are as follows:

  1. Guar gum solution crosslinked with sodium tetraborate
  2. Pancake batter
  3. and Dyed glue crosslinked with sodium tetraborate.
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