In any branch of history, archaeologists, to collect various ideas, they must weave fossil evidence collected on worn, parchment scrolls, or mummified remains. Cosmology, the study of the birth and evolution of the Universe, is totally different. It is the amphitheater where you can become a "witness" of history.
The small dots that adorn the firmament are actually photons that have traveled in our direction for several years or several thousand years. The light of distant objects, meticulously captured by space telescopes, but we reached after a journey that can last up to a dozen or so billion years. And when we look at that light, we are literally looking at the past.
During the past decade, when the observations from space have gradually improved, by looking at the past sempre più antico, si è scoperto che contemplando e studiando questi oggetti si dava - sorprendentemente - uno sguardo al futuro. E il futuro contenuto nei dati delle osservazioni è cospicuamente inquietante, specialmente per una «cosa» nota come energia oscura.
Questa storia incomincia un secolo fa con Albert Einstein, il quale realizzò che lo spazio non è immutabile, come affermava Isaac Newton. Nella sua teoria della relatività, Einstein aveva congetturato, procedendo per illazioni, che lo spazio - e il tempo - possono flettersi, curvarsi e avvitarsi su loro stessi.
Infatti, the universe is so malleable, because - as stated in the mathematics - it can not simply stand still, but it must expand or contract.
For Einstein, this conclusion was unacceptable. He had spent 10 long and arduous years to develop his general theory of relativity, but to him the notion of a restless universe was incredibly strange.
Einstein replied quickly. Modified the equations of general relativity so that the mathematical develop a changeless universe. A static situation as a stalemate in the tug of war, however, requires that two forces are offset, and for now the only power quoted was the gravitational pull. So, we needed a force that moving away celestial bodies. But what could it be?
Surprisingly, he found that a simple modification of the equations of general relativity would have involved an unusual factor that might have stunned even the great Newton: The Gravity - a gravitational force that pushes instead of shooting.
Ordinary matter, such as that of which Earth and Sun, can only generate gravity, creating a gravitational field around itself, but the math said that a far more exotic sources could generate the alter ego of gravity. Einstein called this force that filled the whole universe "cosmological constant", and discovered that exactly compensates for gravity, then stating a static universe. He could finally breathe a sigh of relief.
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