People have tried to answer the question of why the universe has existed for thousands of years. But science has not yet had even a rough answer.
However, in recent years, physicists and cosmologists have begun to actively seek answers. They note that we now have an understanding of the history of the universe, as well as the physical laws by which it exists. This information can provide us with clues to how and why the universe exists.
All from nothing
The general conclusion to which these scientists came: the entire universe, from the moment of the Big Bang to the space strewn with stars and galaxies, in which we now inhabit, came from nothing.
According to them, this had to happen because "nothing" is highly volatile.
Scientists argue that this conclusion follows from two of the most successful scientific theories: quantum mechanics and general relativity.
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How exactly do these theories explain the emergence of everything from nothing? And what does the Big Bang Theory have to do with this?
Particles from vacuum
Quantum mechanics claims that there is no such thing as "nothing." Even the most ideal physical vacuum is actually filled with particles and antiparticles that form out of nowhere and almost instantly disappear back into nothingness.
These virtual particles are so impermanent that they cannot be observed directly, but we know that they are, thanks to the traces left by their short existence.
Space-time from the absence of space and time
From tiny particles like atoms, let's move on to huge cosmic bodies like galaxies. The best theory to describe such large-scale structures is Albert Einstein's general theory of relativity, which explains how space, time and gravity function.
Relativity is very different from quantum mechanics, and until now, no one can perfectly combine the two fundamental physical theories. However, there were those who tried.
The trade-off they have come to is that when quantum theory is applied to the smallest scale of the cosmos, space itself becomes unstable. Space-time is destabilized, rotating and boiling into a foam of space-time bubbles.
In other words, small bubbles of space and time can form completely spontaneously. If spacetime is perceived through the prism of quantum theory, it can oscillate. Thus, virtual space-time models can arise as spontaneously as virtual particles.
Also, in quantum physics, if something isn't impossible, it will surely happen sooner or later.
Bubble universe
It turns out that not only particles and antiparticles can emerge from nothing: the bubbles of space-time can do the same. However, the question arises: how does the jump from an infinitely small space-time bubble to a gigantic universe, which consists of hundreds of billions of galaxies, take place?
The Inflationary Model of the Universe answers this question, which says that from the moment of the Big Bang to the present day, the Universe continues to expand. And if galaxies are moving away from each other, they most likely once were located close.
Universe or multiverse?
At this stage, creating the universe looks easy. Quantum mechanics tells us that "nothing" is unstable, and also that the initial jump from "nothing" to "something" was inevitable. The theory of relativity and the expansion of the universe explains how a tiny bubble of space-time blossomed into a large, rich universe.
A completely logical question arises: why did this happen only once? If a single space-time bubble appeared and it managed to expand to form our universe, what prevents other bubbles from doing the same?
According to physicist Andrei Linde, universes have always arisen, and this process is endless.
When the “bubble” of the new universe stops swelling, it is still surrounded by space that continues to exist. This space could spawn more universes with even more unstable space around them. Thus, as soon as inflation in one universe begins, it should entail an endless cascade of universes. Our universe may be just one grain of sand on an endless beach.
We do not yet have solid evidence of the existence of other universes. But one way or another, these ideas give a completely new meaning to the phrase "something out of nothing."
Hope Chikanchi