When we open our eyes, we can see this beautiful world and see all the good things. Why can we see objects? It's actually very simple, our eyes feel the light coming from this object.
We want to see an object, first of all, the object can self-emit light or reflect the light source, these photons enter our eyes, feedback to the object of the information, so we see the object. If it is an object without photon reflection, then for our eyes, the object is dark, invisible to our eyes.
Our eyes can see light because they feel light from objects, so are the things we see instantaneous? We all know that light also has a speed, and its speed is about 300,000 kilometers per second, which is what we usually call the speed of light.
The speed of light is very fast, is the current known limit speed of human beings, since light has a speed, we and objects will also have different degrees of distance, so that light to reach our eyes will take a certain amount of time, meaning that the things we see are not the things we see now, they are all in the past.
Maybe many friends will say, we live on the earth, see the things around us why do not feel that they come from the past? The main reason is that the distance is too short, the speed of light reaches 300,000 kilometers per second, and the limit distance that we can see with the naked eye is very limited, so that the time difference generated will be very small, small enough to be negligible.
However, when we observe the things of the universe, the vast cosmic distance is measured in light years, and the time difference between this time is very obvious. When we observe a celestial body or galaxy a light-year away, we see things that happened a year ago in that celestial body or galaxy, not the present, because it takes a year for photon information from a light-year away to come to Earth.
Seeing this, some friends have a very interesting question: We stand in the starry sky 6500 light-years away, look back at the earth, can we see the scene of the extinction of the dinosaurs?
For the extinction of dinosaurs, I believe everyone is no stranger, it is a tragic scene that occurred 65 million years ago, an asteroid with a diameter of about 10 kilometers, which triggered a huge ecological crisis after hitting the earth, which led to the end of the dinosaur era, and the dinosaurs that dominated the earth for 160 million years embarked on the road to extinction.
From a scientific point of view, whenever something happens, it will form a piece of information stored, and this information will spread to the universe and spread to the depths of the starry sky. Theoretically, the photons wrapped in information can continue to travel in the universe, and can move a distance of one light-year per year, and 65 million years have passed, so the photon information of the extinction of the dinosaurs has now spread to 65 million light-years away.
If we could reach 65 million light-years away and look back at Earth, would we be able to see the extinction of the dinosaurs? In theory, it can be seen, but in practice, it is not so easy to see this information, it is impossible to see this information through our naked eyes, and it is possible with the help of powerful telescopes.
To what extent does the telescope have to be? We all know that the larger the aperture of the telescope, the more light it receives, and the photon information of the extinction of the dinosaurs is all over the universe, and only by collecting more information can it be possible to restore the scene of the extinction of the dinosaurs.
After the scientists have calculated it, without considering other factors, to collect more photon information 65 million light-years away, the caliber of the telescope may reach 4.36 light-years. Such a caliber is beyond our imagination, equivalent to the distance between the Earth and the NeighborIng Galaxies, with human scientific and technological strength, this is impossible to do.
Of course, this is not considering the telescope aperture under the distortion of space-time, if the factor of space-time distortion is added, the aperture of the telescope will be much smaller. I believe that friends all know that according to general relativity, the essence of gravity is the distortion of space-time caused by massive objects, and the greater the mass, the greater the distortion of space-time caused by it, and the greater the gravitational force.
Distorted space-time can converge light, bring more light into one place, we can choose a better location, this position and the Earth have a massive celestial body or galaxy, so that more light from the Earth can be gathered, and the light can also be "multiple convergence" through the artificial gravitational field, using gravity to gather more light, and the aperture requirements for the telescope will be greatly reduced.
Of course, it can be achieved in theory, but it is not easy to do the same, the requirements for science and technology are very high, and it is not that human beings are not yet able to achieve the scientific and technological strength of the first level, or only the scientific and technological strength of the second level or above can initially meet the requirements.
From this, we can see that the power of science and technology is infinite, as long as the power of science and technology is strong enough, everything in this universe will not exist in secrets. The development of anything cannot disappear out of thin air, but will spread to the universe in the form of photon information.
That is to say, since the birth of the earth, all the evolution of the earth, including the birth and development of human beings, has long been spread throughout the universe. If there is an advanced civilization, building a powerful observation device, it is possible to collect all kinds of information from the earth, so as to understand the evolution of the earth, life information, and know the existence of humans.
From a scientific point of view, for a powerful high-level civilization, there is no secret about everything in the universe, and if a high-level civilization wants to understand the situation of a low-level civilization, it may not need direct contact, even if it is far away from the starry sky, there are ways to understand.
It can be seen that the existence of the earth and the information of human civilization may not be a secret to advanced civilizations, and human beings may have been exposed long ago. In the same way, as long as the scientific and technological strength of human beings develops to a certain extent, we can also collect a large amount of civilization information in the universe, and through this information, we can also restore everything that happened in the past of a civilization.