Sonar cloak

Illinois professor Nick Fang developed a two-dimensional acoustic cloak that makes objects in the center invisible to sonar and other ultrasound waves.

Cloaking is no longer scientific fiction.

Solar cells on toilet paper

Researchers have developed a working solar cell that can be put on toilet paper.

In the figure here, the solar cell is flexible enough to be folded into an airplane. A video at the link shows a video of the folding and that the cell does produce a current when illuminated.

Atomic weights: Your results may vary

Seems that elements can have a range of atomic weights. Why, well because:

Some elements have more than one stable (nonradioactive) isotope—variants of the same substance, but with different numbers of neutrons in their atomic nuclei that alter the mass. (The element's identity is determined by the number of protons.) In those cases the atomic mass listed on the periodic table has traditionally been defined as an average depending on how common each isotope is in nature. But that average is not the same every place on Earth, or in every situation. Just as radiocarbon dating can place a substance in time, isotopic analysis can also pinpoint its location.

So, now instead of carbon listed as being 12.0107 atomic mass units with a measurement uncertainty of about 0.0008, it has an official atomic weight of [12.0096; 12.0116], where the brackets and semicolon indicate an interval of atomic weights. The interval doesn't reflect an uncertainty in measurement precision but rather a real variation of atomic weight from substance to substance. Only 10 elements will have these new intervals, because the others have at most only one stable isotope or because upper and lower bounds have not been quantified.

Speaking of atomic weights, let me recommend the book The Joy of Chemistry: The Amazing Science of Familiar Things . I should say more later, but for now this is a great book to give a layperson a good overview of chemistry. And it includes experiments you can do at home with common household items.

Invisibility: Now available

The idea of invisibility has always intrigued people from the Invisible Man to stealth airplanes. Now, there's a new cloaking material that can actually hide objects.

Two independent groups have now achieved this feat [of invisibility], by building transparent 'carpet cloaks', made from calcite crystals, that lie over the object to be hidden.

Carpet cloaks render covered objects invisible by bending light rays as they enter the cloak and then when they exit it -- after they have bounced off the hidden object. The light is deviated in such a way that the rays seem to have been reflected directly from the ground underneath the object -- as though the object was not there.

Seems that special crystals can bend the light rays to hide the object.

That's pretty neat.