If you watch the night sky above your head, you are always looking into the past. The distances in space are so great that the light that reaches us from it is always delayed. So does this mean that aliens inhabiting a planet 65 million light years away can see our extinct dinosaurs?
“Because the universe is so huge, we will never know what is happening in it right now,” explains Jakub Rozehnal, Director of the Štefánik Observatory in Prague on Petřín and the Planetarium. “For example, if something happens on Mars, we will catch it in 20 minutes. When you observe the Sun, you see what it looked like eight minutes ago.”
What would the world look like today if the dinosaurs had not gone extinct. Would a human be born at all?
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Dinosaurs appeared on our Earth about 250 to 235 million years ago and became extinct 66 to 65 million years ago. So creatures living 65 million light-years away should be able to see these vertebrates hunting, running or relaxing by looking through a telescope. In theory, yes. In practice, it is much more complicated.
Earth from space
Light is everywhere. The photons that make it up bounce off any opaque object and fly in all directions. When these elementary particles are captured by the eye, we will see the object. The greater the distance between our sense organ and the body, the more the photons scatter and we have trouble capturing them.
The Webb Telescope stretched the solar shield in space. He has completed half a long pilgrimage
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That’s why astronomers use a telescope. This instrument collects multiple photons that have bounced off a star or bodies. Objects can thus be seen more clearly. The further away the observed object is, the more powerful the peephole should be.
The largest telescope in the world, the James Webb Space Telescope, has a lens with a diameter of 6 meters with a resolution of 0.1 arcsecond. Using it, experts can easily see the crown at a distance of more than 40 km. But even this technologically perfect instrument sees galaxies several billion light-years away only as small clumps of light dust. If we wanted the object to be sharper, it would have to be no more than half a million light years away.
Observing life on Earth
Assuming that the inhabitants of a planet 65 million light-years away had a similar telescope and wanted to see our Earth, its lens would have to be more than 60 km in diameter. Even then, however, the Blue Planet would only appear as a dot in the sky. If they really wanted to capture dinosaurs, the lens would have to be more than 4.5 light-years across, which is 4.257 x 1013 kilometers. That’s more than the Earth itself measures.
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Source: Youtube
However, such a huge telescope would cause a serious problem from the point of view of physics. There are certain rules that govern the universe. It is true that the average density of a substance is equal to its total weight divided by its total volume. For example, iron will have a smaller volume than bodies of the same mass made of a less dense material. If the mass were to increase, the object would bend space-time and a black hole would form in place. A lens made of glass could therefore have a maximum diameter of 28 light minutes.
Source:
www.region.rozhlas.cz, www.sk.wikipedia.org, www.buddymantra.com
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