Added: Jamisha Tannenbaum - Date: 01.01.2022 09:44 - Views: 21562 - Clicks: 7390
The blackbody attraction between a hot tungsten cylinder and a cesium atom is 20 times stronger than the gravitational attraction between them. But the researchers have shown that a glowing object actually attracts atoms, contrary to what most people — physicists included — would guess. The tiny effect is much like the effect a laser has on an atom in a device called optical tweezers, which are used to trap and study atoms, a discovery that led to the Nobel Prize in Physics shared by former UC Berkeley professor Steven Chu, now at Stanford, Claude Cohen-Tannoudji and William D.
Until three years ago, when a group of Austrian physicists predicted it, no one thought that regular light, or even just the heat given off by a warm object — the infrared glow you see when looking through night-vision goggles — could affect atoms in the same way. UC Berkeley physicists, who are expert at measuring minute forces using atom interferometry, deed an Looking for hot bodies to check it out. When they measured the force exerted by the so-called blackbody radiation from a warm tungsten cylinder on a cesium atom, the prediction was confirmed.
The attraction is actually 20 times the gravitational attraction between the two objects, but since gravity is the weakest of all the forces, the effect on cesium atoms — or any atom, molecule or larger object — is usually too small to worry about.
As gravity measurements become more precise, though, effects this small need to be taken into .
The next generation of experiments to detect gravitational waves from space may use lab-bench atom interferometers instead of the kilometer-long interferometers now in operation. Thermal images like this record blackbody radiation, essentially the infrared light given off as a body cools. For very precise inertial using atom interferometers, this force would also have to be taken into. Optical tweezers work because light is a superposition of magnetic and electric fields — an electromagnetic wave.
The electric field in a light beam makes charged particles move.
In an atom or a small sphere, this can separate positive charges, like the nucleus, from negative charges, like the electrons. This creates a dipole, allowing the atom or sphere to act like a tiny bar magnet. The electric field in the light wave can then move this induced electric dipole around, just as you can use a bar magnet to shove a piece of iron around.
The shiny tungsten cylinder can be seen at top through a window into the vacuum chamber of the atom interferometer The cesium atoms are launched upwards through the circular opening below the cylinder. They measured the effect by placing a dilute gas of cold cesium atoms — cooled to three-millionths of a degree above absolute zero nanoKelvin — in a vacuum chamber and launching them upward with a quick pulse of laser light. Half are given an extra kick up towards an inch-long tungsten cylinder glowing at degrees Celsius degrees Fahrenheitwhile the other half remain unkicked.
When the two groups of cesium atoms fall and meet again, their matter waves interfere, allowing the researchers to measure the phase shift caused by the tungsten-cesium interaction, and thus calculate the Looking for hot bodies force of the blackbody radiation.
Our physical attraction to hot bodies is real, according to UC Berkeley physicists. Sorry, your blog cannot share posts by .
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