Rings and rainbows
A team of scientists claim to have discovered a thin ring of light called the photon ring around the first black hole to have its image taken, the supermassive black hole in the galaxy M87. But he does not persuade unbelievers; Emily Conover reported in “The photon ring cry of the physics controversy” (SN: 9/24/22, p. 8).
Assuming that the Earth and the photon ring are in the same plane, the reader James P. Rice They wondered why we see light as a circle rather than a straight line.
“The photon ring is a little like a rainbow” Physics writer James R. Riordan he says “It’s an optical effect, not a physical ring.” Rainbows are caused by the way droplets affect the paths of light. A man can see rainbows in the rain before them, as long as the sun is behind them; but where the rainbow appears to the seer, it is changed according to the man’s standing in front of the sun;
Similarly, the photon ring is caused by the influx of a black hole onto the paths of light; Riordan he says The photon circle will appear as a round circle around the black hole, no matter which side of the black hole you look at. “You can’t be in the plane of the photon ring at the end of the rainbow,” he said.
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Reader Marc Sapir it was asked whether light could bend from the primitive solar system and come to us through space travel so that we could someday see the events of the Earth’s past.
“Everything turns on a little bit,” he said Sam Grallaa scientist at the University of Arizona in Tucson. But let’s go back to the light, it must change a lot.
Our sun, for example, “bends light a little less than a thousand times, so that it will not be able to see our past.” Gralla he says If, hypothetically, the Sun collapsed into a black hole of the same mass, “then it could bend the light in a circle, which would be pretty cool,” he said. “But only a small part of the emitted light is bent, so we have to see the amazing telescopes.” Even if we had such telescopes, humans and other life on Earth would not survive without sunlight. Gralla he says And alas, our sun is going to be a red giant when it dies, not a black hole.
Some light from our early solar system was able to reach Sagittarius A*, the black hole at the center of the Milky Way. “Sgr A * can bend a lot of light” Gralla he says “But unless the next light is emitted, the tiny particle is actually bent.” For light from our solar system to return to us, it must approach Sgr A* in precisely the right direction, he says. “The proverbial needle in the haystack.”
“Still, it’s funny to think that aliens near black holes could see themselves in the black hole’s mirror this very minute.” Gralla he says
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