The light propagates in space at a speed of 300,000 kilometers per second. E 'was shown by the theory of relativity Einstein's special that this is the highest possible speed in the universe. When you approach the speed, time slows down. In fact, in particle accelerators like the CERN Geneva Note that if you accelerate a particle (eg muon) at a rate of 99.5% of that of light, its life expectancy increases by 10 times. This because Space and Time are not two separate entities, but are only two aspects of one reality which physicists call the "Spacetime . The light in certain physical experiments behaves as if it were made of particles (photons, mass almost nothing) and other physical experiments behaves as if it were made of waves. These waves, unlike sound waves propagate in a vacuum, however. We speak therefore of wave-particle duality. In fact, the theories are true, and two: they are our attempt to describe unknowable reality. The speed of light is an enormous speed, but compared to the vastness of the Universe, we realize that is not true. Already come from the Sun to our eyes, the light takes 8 minutes, so the Sun's image that we see now is actually the sun as it was eight minutes ago.
The closest star to us (considering not the Sun) is Proxima Centauri which is 4.2 years-light. This means that when I look at that star, I see it as it was about 4 years and three months ago, because this is the time that his image has taken to arrive at my eyes and then to my brain. But if I go with her eyes to observe a faint haze located in the constellation Andromeda , well that's the Andromeda galaxy (consisting of 300 billion stars) is 2 and a half million light years, then see how it was 2 and a half million years ago, when that image is playing on Earth there was still the Man!
But Andromeda is one of the galaxies nearest to us: there are galaxies away from us millions and billions of light years. When we look at the telescope which is a galaxy a few billion light years, probably see an object has disappeared with all possible civilizations that they were (think that the average lifetime of a star as the sun is 10 billion years).
As you can see, just look up to heaven to go back in time: time and space are inextricably linked.
0 comments:
Post a Comment