The speed of light is a speed "barrier" in the universe, which means that any object with mass and any information cannot fly faster than the speed of light .
But super-light speed is still expected by many people. Although Einstein has already told us that the speed of light is the limit of cosmic speed , it has not completely locked the door to "super-light speed" and still opened "a door" for us. window".
For example, from a theoretical analysis, there is still the possibility of "super-light speed". The legendary "wormhole" and "warp engine" theories can both allow humans to instantly cross vast interstellar distances and achieve "super-light speed", and nature is not opposed to this.
So, what if we could instantly travel to a planet a thousand light years away and see the earth a thousand years ago?
is a purely theoretical analysis and can indeed be seen. For example, we all know that the sun we see every day is not the sun at this moment, but the sun 8 minutes ago. Because the speed of light is limited, 300,000 kilometers per second, and the distance between the sun and the earth is 150 million kilometers, it takes about 8 minutes for light to reach the earth.
Similarly, if a planet is a thousand light years away from the earth, then the planet we see on the earth is also what it looked like a thousand years ago.
But in fact we cannot see the earth a thousand years ago, because the distance of a thousand light years is too far. Spanning the vast interstellar distance of a thousand light years, photons will encounter various "obstacles", such as interstellar dust and gas molecules, other celestial bodies, and various cosmic rays.
During the entire process, the energy of the light reflected by the earth will weaken little by little. Eventually, even if it reaches the planet a thousand light years away, it will have long since weakened into invisible light.
The more important point is that the earth is illuminated by the powerful halo of the sun. The result is that on a planet a thousand light years away, you cannot see the light reflected by the earth even if there is no obstruction.
One fact says it all. Scientists have not directly seen any exoplanet (outside the solar system). One of the main reasons is that the planet appears too dim in front of the parent star (star), so that even the most powerful telescopes cannot be used. It is impossible to directly observe the existence of exoplanets.
The exoplanets discovered by scientists are all discovered through indirect means (such as the transit effect).
The nearest star system is Proxima Centauri , which is only 4.3 light-years away, but even so, we cannot see planets 4.3 light-years away, let alone a thousand light-years away.
