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Wednesday, November 23, 2011
A young Leonardo
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."
Thursday, November 17, 2011
Earth's close encounter of asteroids
Should Earth's close encounter trigger asteroid avoidance research? | Opinion | The Engineer
Tuesday, November 15, 2011
Leonardo, Genio e Mito
http://www.lavenaria.it/mostre/ita/mostre/archivio/2011/leonardo.shtml
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
Tuesday, November 8, 2011
Bee rescue
http://www.abc.net.au/science/articles/2003/05/08/2045526.htm#artBookmarks
"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
http://en.wikipedia.org/wiki/Stingless_bee
¿Un Futuro Sin Abejas?
Especial Abejas: ¿Un Futuro Sin Abejas?
Thursday, October 27, 2011
Giant Waterworld Around Naked Eye Star
"55 Cancri A is a Sun-like star some 40 light years away. It has an apparent magnitude of about 6 and so is visible to the naked eye in the constellation of Cancer.
This star is unusual in that it is just one of a handful that are known to have at least 5 planets. The innermost of these planets--55 Cancri e--was discovered in 2004 and has since had plenty of attention from astronomers. Various groups have observed the the changes in radial velocity that it causes its parent star. This tells them about that it orbits its star every 18 hours and that its mass is about 8 times Earth's or about half Neptune's."
Friday, October 14, 2011
Mela, Pomponius
Munich Digitization Center
Digitised works/ Author: Mela, Pomponius
http://www.digital-collections.de/index.html?c=autoren_index&l=en&ab=Mela%2C+Pomponius
Thursday, October 13, 2011
Indos
De chorographia, Liber III
"Mais à l'autorité des anciens philosophes et d'Homère, qui ont prétendu que la terre était de tous côtés environnée par la mer, on peut ajouter celle de Cornélius Nepos, qui, étant plus moderne, est par conséquent plus sûr. Or, cet auteur rapporte, à l'appui de cette opinion , le témoignage de Q. Metellus Celer, auquel il fait dire qu'étant proconsul dans la Gaule, le roi des Botos lui fit présent de quelques Indiens , et que, s'étant informé d'où ils étaient venus, il apprit que, les tempêtes les ayant emportés loin de la mer des Indes, ils avaient été jetés, après un long trajet, sur les rivages de la Germanie. Le reste de la côte asiatique est donc baigné au nord par une mer sans bornes; mais cette partie est couverte de glaces éternelles, et par conséquent déserte."
Louis Baudet translation
To the ancient philosophers and Homer, who claimed that the land was surrounded on all sides by the sea, we may add Cornelius Nepos, who, being more modern, is therefore more reliable. However, this author reports in supporting this fact, the witness of Q. Metellus Celer: when he was proconsul in Gaul, the king of Botos made him a present of a few Indians, and that, being informed of where they came from, he learned that the storms have swept away them of the Indian Ocean. They were thrown, after a long journey, on the shores of Germania. The rest of the northern Asian shores are surrounded by the sea, but this part is covered with eternal ice, and therefore deserted.
King Arthur's round table
How to measure the stair angle
use a protractor (available at most hardware stores) to determine this angle.
I am proposing that Kha the architect at Deir El-Medina, Egypt, supervisor of the projects of three kings of the 18th Dynasty used his protractor to check the inclination of stairs for instance. You can see it at the Egyptian Museum of Torino. Read more at http://stretchingtheboundaries.blogspot.com/2011/08/khas-protractor.html
Saturday, October 8, 2011
Kha
Back to Kha's protractor
In the post "Kha's protractor", I have discussed an object found in the tomb of an ancient egyptian architect, Kha. It can be used to measure angles.Plums, levels, protractors , compasses and so on are instruments for surveying. See http://en.wikipedia.org/wiki/Surveying and the table http://en.wikipedia.org/wiki/File:Table_of_Surveying,_Cyclopaedia,_Volume_2.jpg
In this table there is the image of a compass rose. We can start from it and go back to the Kha's rose.
Tuesday, October 4, 2011
Romans in America?
In fact, there's a growing amount of evidence suggesting that a lot of the familiar history of human exploration and "discovery" by our ancestors as we were taught it may be quite wrong. There is hard evidence of ancient civilizations making their mark in places where, according to traditionally accepted history, they just shouldn't be. Here's an overview of some of the most remarkable and fascinating cases."
read more
At http://paranormal.about.com/od/ancientanomalies/a/History-Mystery-Ancients-In-America.htm