After 72 hours of exposure to ambient light, strands of nanoparticles twisted and bunched together. Credit: Nicholas Kotov
Posted on 03/25/2010 10:57:48 AM PDT by neverdem
After 72 hours of exposure to ambient light, strands of nanoparticles twisted and bunched together. Credit: Nicholas Kotov
Light can twist matter, according to a new study that observed ribbons of nanoparticles twisting in response to light.
Scientists knew matter can cause light to bend – prisms and glasses prove this easily enough. But the reverse phenomenon was not shown to occur until recently.
The researchers assembled strings of nanoparticles, which are tiny clumps of matter on the scale of nanometers (one nanometer is one billionth of a meter). In a darkened lab, the scientists linked nanoparticles together into ribbons. At first the nano ribbons were flat, but when a light was shone on them, they curled up into spirals.
The discovery was so novel, the researchers were skeptical of their own results at first.
"I didn't believe it at the beginning," Kotov said. "To be honest, it took us three and a half years to really figure out how photons of light can lead to such a remarkable change in rigid structures a thousand times bigger than molecules."
The surface of the nanoparticles in this experiment were made of cadmium sulfide. To begin with, they had a slightly negative electromagnetic charge. But when photons, or particles of light, hit the nanoparticles, their energy excited electrons on the nanoparticles, causing chemical reactions that made them even more negatively charged. Since two negative charges repel each other, the nanoparticles began to repel more strongly.
"What's happening is a layer of nanoparticles starts repulsing from the others, so it creates mechanical stress, and in order to release this stress the ribbon twists itself," Kotov told LiveScience...
(Excerpt) Read more at livescience.com ...
Of course it is.
Notice that those things we call "light bulbs" turn dark or black when they've collected all the dark they can hold? Some get so full of dark matter they won't let any light in, so they look silvery and reflect your image (light) back at you! ;^)
Not sure why this seems to be a big deal; we've used different frequencies to cause physical actions on the atomic/molecular level for decades.
One of my favorite quotes of all time: “Those who say science and religion are incompatible are missing the point of both.”
I comprehensively verified that theory through extensive experimentation with a magnifying glass and some unlucky ants as a young lad.
If I'm remembering correctly back in the mid to late 60's photocell operated relays were fabricated from cadmium sulfide as the photo sensitive element used to control the relay operation. I seem to recall selenium also have photo sensitive properties. Selenium was mainly used in "solid state" rectifiers to produce DC from AC input without resorting to vacuum tubes or mercury filled "ignitrons". This technology was in use before WWII and most contemporary EE have never even heard of it.
Regards,
GtG
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No, photons carry both energy and mass. This particular effects seems to be due to the energy they contain. But their momemtum can have large scale effects as well.
For example, if you had a really powerfull laser on a spaceship, it could be used to propel the ship. Shine it in one directoin and you accellerate in the other direction. Not very quickly unless it's really honking big laser, but move you will. Of course such a laser could be used as a weapon as well. Or for signaling over very very long distances.
The momentum of a photon, like it's energy, is only dependent on it's wavelength. (or color if it happens to fall in the visible spectrum).
OK.
So the other direction, lasers can now blast an incoming missile by heat and energy input ..... 8<)
Thanks for the ping.
Heat is energy. But, IIRC, some of the damage mechanism for short pulse lasers is due to momentum transfer. Short of like pounding on the missile with a ball peen hammer, only much harder.
But other lasers, such as the one on the ABL 747, do there thing by energy deposition.
Cheers!
Right on. Science is man's halting effort to read God's handwriting directly. We've translated a few letters of the alphabet.
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