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Light-bending black hole mimic is first you can watch - acrylic glass

by:Cailong     2019-08-11
Light-bending black hole mimic is first you can watch  -  acrylic glass
Plastic black holes capture light like real deals and are the first natural or artificial structures that can actually be viewed.
Unlike the real thing, it's not dangerous-but it helps to uncover the mystery of one of nature's most strange objects, and possibly even energy applications --
Harvesting devices like solar cells.
Black holes are known for consuming light or anything else.
But this fate is only waiting for an object to be sucked through a point called the Horizon of events.
What is not well known is the photon ball of the black hole, which is a distorted space area --
Time outside the horizon, just catching light in a curved path.
Astronomers have never observed a photon ball-even outside a real black hole-because, by definition, the trapped light cannot escape and reach your eyes, so you can see it.
To visualize the process, Liu Hui of Nanjing University in China and his colleagues built a black hole.
In nature, black holes devour and capture light through its enormous gravity, which is difficult to reconstruct in the laboratory, let alone very dangerous.
Instead, Liu's team used a piece of plastic-and simulated the effects of gravity by changing its refractive index, which determined how much a substance would bend to light.
The refractive index is different for different materials.
That's why a straw sticking out of a cup of water looks bent & colon;
Water is more curved than air, so the refractive index is higher.
The material with the ever-changing refractive index will take this to its extreme, and many small bends will produce smooth curves-just like the photon sphere of a black hole.
Liu's team added quantum dots to the molten acrylic glass, a small piece of semiconductor material that emits fluorescence when illuminated, and then poured the mixture into a rotating quartz sheet, slowly
They placed a microscopic polystyrene ball in the center, as an anchor, the thickest material, closest to the ball, and it will become thinner as the ball gets farther and farther.
"This makes the change in the effective refractive index the same as the change in the curvature of the space around the black hole," Liu said . ".
In fact, the Einstein field equation used to simulate black holes can describe the behavior of light in acrylic.
By firing a laser through the material, you can observe that the artificial black hole is working and you can see other familiar gravity effects.
The beam that is relatively far away from the microsphere bends slightly towards it before proceeding forward.
When gravity produces the same effect in space, it is called the gravitational lensing effect.
This happens whenever a beam passes through a huge object such as a star or galaxy, and when the beam travels along a curved space, it changes the path of the beam --time-
It can be used to better observe distant objects, such as exoplanets.
However, in the case of an artificial black hole, as the laser moves towards the polystyrene sphere, the pull increases and eventually there is a point that will make the light completely bend.
Previously, artificial black holes were created to mimic the event horizon of black holes. in order to detect a mysterious process called Hawking radiation, this is the first man-made object to reconstruct the photon sphere.
More importantly, unlike real black holes, photon balls can be imaged due to quantum dots.
Although, like in a real black hole, the actual light captured is still invisible, the quantum dots absorb some of them and emit red light at different angles, let it escape the control of the black hole.
This provides an accurate trajectory of the true photon ball path and can be imaged through the camera.
"Our work reports a very simple and clever way to mimic the trapped light around the black hole," Liu said . ".
Ulf Leonhardt of The Rehovot Weizmann Institute in Israel said Liu's structure provides another way to study black holes.
"This shows that there is no big mystery about the lens effect in general relativity, and you can do the same thing with ordinary materials.
Liu said the model can be used to study the effects of general relativity around real black holes, but the ability to capture light can also have more practical applications.
"It can be very useful for solar cells, photon detectors, micro lasers and many other energy collection devices.
"Journal reference and colon;
Natural Photon Technology; 10. 1038/nphoton. 2013.
Fuguang Mountain and colon; 10. 1038/nphoton. 3. 247
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