The Umich link is about invisibility to radars. I clearly mentioned in my post that I am talking about invisibility to the human eye. The difference has been explained in a previous post. (Radars produce their own radiation and search for its reflection, whereas the human eye relies on ambient light.)
The BBC link is about invisibility in deep space, where there is no ambient light. The military applications mentioned are also assuming similar sensors - not that it would be invisible to human eyes.
The last link is also about space applications.
In short, a perfectly black object in front of you will not be invisible - your eyes can perceive its existence (ie, it is visible) because it can distinguish it from the surrounding. A perfectly transparent object will be invisible, because light would simply pass through it as if there was no object there.
LOL. Are you for real ?
....A very black carbon nanotube coating renders objects into silhouettes and could form the basis of a future stealth device. Like a cloak of invisibility, the material makes things disappear completely when viewed against a black background.
"The most exciting thing is that it makes any 3-D object look like a shadow," said researcher Haofei Shi at the University of Michigan. "You know something is there but you don't know what it is."
The effect works even under direct light and from multiple viewing angles, showcasing the first perfect light-absorbing coating, Shi said. Capable of swallowing a broad spectrum of light, the paper-like material has potential for
roomy stealth airplanes and sun-gulping
solar cells.
"You can wear a coat made of this material and you will look like a flat sheet of black paper," said co-researcher Jay Guo at the University of Michigan. "They cannot perceive any 3-D aspects of the person in the coat … ...
Nano Paint Could Make Airplanes Invisible to Radar | MIT Technology Review
A new nanostructured coating could be used to make paints for stealth aircraft that can’t be seen at night and that are undetectable by radar at any time of day. The coating, made of carbon nanotubes, can be used to cloak an object in utter darkness, making it indistinguishable from the night sky.
Carbon nanotubes have many superlative properties, including excellent strength and electrical conductivity. They are also the blackest known material. The long straws of pure carbon, each just a few nanometers in diameter, absorb a broad spectrum of light—from radio waves through visible light through the ultraviolet—almost perfectly. Researchers are taking advantage of this perfect absorbance in highly sensitive imaging sensors and other prototype devices.....