Applied Physics

Donuts, electric current and quantum physics - if you are a theoretical physicist interested in topological insulators, materials whose ability to conduct electric current originates in their topology, it makes perfect sense.

The easiest way to understand what "topological" means in this context is to imagine how a donut can be turned into a coffee cup by pulling, stretching and moulding - but without cutting it.

Topologically speaking, therefore, doughnuts and coffee cups are identical, and by applying the same principle to the quantum mechanical wave function of electrons in a solid one obtains the phenomenon of the topological insulator. This is advanced quantum physics, highly complex and far removed from everyday experience. 

I’ll demonstrate how I built a simple mirror or filter mount out of Lego. This mount can then be attached to a pan and/or tilt mechanism.

Follow me on Twitter: @SteveSchuler20.

Also see my previous article to see how I built a large lens holder for my Lego optics lab.

Parts needed

1 Plate 2 X 8
2 Technic Beams 1 X 2
2 Arm section with pin and two fingers

Here’s how I built my Lego mirror/filter holder:

By Michael Greshko, Inside Science - In the classic 1989 film Back to the Future 2, intrepid time traveler Marty McFly jumps ahead a few decades, to October 21, 2015.

Luxury car manufacturer Lexus appears to be ready for him. This week, they announced that they've built a "real, rideable" hoverboard. 

They've even released video of it, oozing fog and mysteriously floating over what looks like a concrete sidewalk. Check out the 38-second teaser for yourself:
For my Lego Optics Lab I have so far built a beam splitter, and a small lens holder. The beam splitter article got a link on io9 (my name is misspelled) and on Scientific American.

In my previous article, I started building a Lego optics lab with a dichroic prism I salvaged from an old computer projector that I took apart (I used the prism to build a beam splitter). I also salvaged several lenses, mirrors, and filters. To continue the Lego Optics Lab project I’ll demonstrate how I built a lens holder for the several small lenses from the projector. My lens holder uses mostly standard Lego parts except for the shock absorber brick.

A lot of problems, associated with the mixing of the liquid in the microchannels, could be solved via proper organization of the inhomogeneous slip on the walls of these channels, according to a joint group of Russian and German scientists lead by Olga Vinogradova, professor at the M.V. Lomonosov Moscow State University. 

 I finally took apart a broken computer projector. Some of the optics were burned or broken but I managed to salvage several lenses, mirrors, filters, and a curious little glass cube.  

I've talked before about how life on present day Mars could be vulnerable to Earth life. If only humans could be sterilized of other life, like a plant seed. But sadly, we can't do that, and it would kill us to try. Recent ideas, and experiments in Mars simulation chambers suggest that there may be liquid water habitats on the surface of Mars. They may be no more than droplets of water a few millimeters in diameter, but these still are, as Nilton Renno said, "Swimming pools for a microbe".

A team of engineers have created tiny acoustic vortices and used them to grip and spin microscopic particles suspended in water.

The research by academics from the University of Bristol's Department of Mechanical Engineering and Northwestern Polytechnical University in China, is published in Physical Review Letters. The researchers have shown that acoustic vortices act like tornados of sound, causing microparticles to rotate and drawing them to the vortex core. Like a tornado, what happens to the particles depends strongly on their size.

By Joel Shurkin, Inside Science -- Super Balls are toys beloved by children because of their extraordinary ability to bounce. Physicists love them for exactly the same reason.

Drop a baseball on the floor and it will hardly bounce at all. Drop a Super Ball from shoulder height, and it will bounce back 92 percent of the way to the drop-off point. Super Balls also are just as bouncy vertically as they are horizontally, and they spin oddly.