Benvenuti in queste pagine dedicate a scienza ed arte. Amelia Carolina Sparavigna

Wednesday, November 23, 2011

A young Leonardo

A young Leonardo da Vinci - A superposition of images.
See how I processed them at
and also

Friday, November 18, 2011

Turning darkness into light

"Quantum mechanics tells us that the vacuum is not empty but is filled with virtual particles that pop into and out of existence. Normally these particles are hidden from our view, but now a team of physicists has used the electrical equivalent of an ultrafast mirror to convert virtual photons into real electromagnetic radiation. Known as the dynamical Casimir effect, it was first predicted more than 40 years ago. The static Casimir effect ... 1948, involves two perfectly reflecting parallel mirrors that, when placed in a vacuum, will be attracted to one another. This attractive force is caused by the radiation pressure exerted by virtual photons outside the mirrors and the fact that this pressure exceeds the pressure between the mirrors because of the limited number of modes of electromagnetic vibration that are permitted within this gap. In other words, the force results from a mismatch of electromagnetic modes in space. The dynamical effect was proposed by Gerald Moore in 1970 and is caused by a mismatch of modes in time. The phase of an electromagnetic wave goes to zero at the surface of a mirror, if that mirror is a perfect electrical conductor. When the mirror is moved slowly through a vacuum, this zero point can move with the mirror. However, if the mirror is moved at a significant fraction of the speed of light, then the electromagnetic field does not have time to adjust but instead becomes excited and as a result generates real photons. Put another way, the mirror prises virtual photons (always produced in pairs) apart so that instead of rapidly annihilating, the particles are free to remain as real photons."

How to turn darkness into light - physicsworld.com

Thursday, November 17, 2011

Earth's close encounter of asteroids

"After yet another narrow encounter with an asteroid the size of an airship earlier this week, do we need to pay more attention to technology that could protect our planet and its inhabitants from these turbo-charged cosmic fireworks?"
Should Earth's close encounter trigger asteroid avoidance research? | Opinion | The Engineer

Tuesday, November 15, 2011

Leonardo, Genio e Mito

Alla Venaria Reale (Torino) si apre la mostra su Leonardo da Vinci. Il titolo è "Leonardo, il Genio, il Mito".
In esposizione vi è l'autoritratto della Biblioteca Reale e il Codice del Volo.
In una pagina del codice, sotto la scrittora di Leonardo, vi è un ritratto, forse un suo autoritratto da giovane.
Vedi http://staff.polito.it/amelia.sparavigna/da-vinci-portrait.html

Image processing della pagina del codice, A.C. Sparavigna

Tuesday, November 8, 2011

Bee rescue

Stingless bee rescue,   by Wendy Pyper
"Of the 1600 species of wild bees native to Australia, about 14 species are stingless. As stingless bees are harmless to humans, they have become an increasingly attractive addition to the suburban backyard or verandah.
Most stingless bee keepers are not after honey. Rather, they enjoy the sense of conserving a native species whose original habitat is being increasingly cleared and developed. In return, the bees pollinate crops, garden flowers and bushland during their search for nectar and pollen."

Stingless bees

Ci sono api e api...

¿Un Futuro Sin Abejas?

s"Misteriosamente, las abejas mueren o se extravían y no pueden volver a su reducto, por lo que sus poblaciones se diezman inexplicablemente. Si ellas desaparecieran, alimentar a los 7 mil millones de habitantes de la Tierra, será muy difícil."
Especial Abejas: ¿Un Futuro Sin Abejas?