The concept of multiple universes goes back to the 6th century, when the pre-Socratic Greek philosopher Anaximander first suggested the idea of infinite worlds.
However, the ideas of the multiverse gained scientific weight only in the 1980s, along with the theory of inflation, which not only explained why the cosmos is so flat and smooth, but also predicted an endless creation of new types of ‘bubble’ universes ‘.
And now, it seems that scientists are finally closer than ever to finding the evidence that could prove the existence of the multiverse.
One hundred years after Edwin Hubble’s proof that other galaxies are out there, we may soon find evidence of the existence of the multiverse
Image credits: ESA Hubble
Image credits: ESA
Image credits: ESA Hubble
The most developed model of a multiverse known to date is cosmological inflation. The theory was first proposed by physicist Alan Guth in the 1980s, who suggested that after the Big Bang, about 13.8 billion years ago, the universe rapidly expanded exponentially for a fraction of a second. This process can be compared to a large microscope that magnified the random temporal variation in the amount of energy at a point in space, corresponding to a scale of less than 10-28cm, at cosmological distances leaving traces in the cosmic microwave background and in the distribution of galaxies.
Inflation is also part of the currently known model of the universe, called Lambda Cold Dark Matter (LCDM), in which the shape of the universe’s trajectory resembles a funnel that is growing and expanding further over time.
At the heart of this cosmological inflation is the idea of ’bubbles’ – infinite unique universes that were created when some parts of space-time expanded faster than others.
A Russian-American theoretical physicist, Andrei Dmitriyevich Linde, later observed that the exponentially rapid expansion of the universe could occur not only in the false vacuum, but also during a slow transition away from the false vacuum. Therefore, in 1983, he suggested another version of the inflationary theory – chaotic inflation. The physicist in his study explained inflation as a natural (and may even be inevitable) consequence of the initial chaotic conditions in the early universe.
However, in 2013, when the European Space Agency announced a map of the cosmic microwave background (CMB) made from data collected by a satellite called Planck, the theory of inflation faced some serious challenges.
While multiverse ideas gained scientific weight in the 1980s with the inflation proposal, nowadays scientists are looking for alternative ideas.
Image credits: ESA
Image credits: NASA
Image credits: NASA
Therefore, in recent years, many cosmologists have been looking for alternatives that can finally reveal the history of the history of our universe. One such could be the cyclic universe theory, which states that the universe continually forms itself in cycles.
“What I didn’t like about inflation was that there are very few true predictions – you don’t get much more than you put in. It just struck me that there had to be a better explanation,” said Neil Turok, a physicist at the University of Edinburgh, UK.
The scientists who proposed the cyclic model are suggesting that the Big Bang was not the beginning of time. They believe there was another phase leading up to it, which has multiple cycles of contraction and expansion that repeat endlessly.
“It allows us to go beyond the Big Bang, but without any magical philosophical issues, because time has always existed in the past,” said Stephon Alexander, a professor of physics at Brown University and co-inventor of an inflation. model of the universe based on string theory.
As another concept that doesn’t invoke cosmic inflation, in 2018 physicist Neil Turok proposed a mirror universe — one that is stretching back in time from the Big Bang.
While the inflationary theory states that the early universe exploded into an infinite number of different universes, known as the inflationary multiverse, the mirror universe theory is much more economical and predictable.
“It’s an approach that was born out of a certain sense of frustration with previous approaches. In my opinion, it had all become quite complicated and contrived, including my own approaches,” explained Turok.
“I think we may be on the verge of the next big revolution in theory. It will be inspired by data, by the failure of traditional paradigms. It will change our view of the universe,” he added.
Turok and his team’s prediction is that our universe may have a twin in which time moves backwards.
Image credits: Physics
“We know that the early universe was dominated by hot radiation. This means that, if you turn the clock back from there, the size of the universe shrinks to zero in a very simple way. Mathematically, you can follow a straight line that intersects the Big Bang. This allows us to extrapolate back to another copy of the ‘mirror image’ of our universe on the other side of the Big Bang,” the physicist shared the revolutionary idea.
“The two sides of the universe grow steadily in opposite directions away from the Big Bang, governed by the known laws of gravity and particle physics. The extreme simplicity of the large-scale universe, which is very smooth and flat, is a direct result of the simplicity of these laws,” he added.
Turok’s mirror universe theory not only suggests a simpler explanation of the universe’s history, but also aims to provide some answers about dark matter.
“We realized that our idea could solve the puzzle of dark matter, the mysterious substance that holds galaxies together, in terms of particles that we haven’t seen directly but already have strong evidence for,” shared Turok.
“These are called right-handed neutrinos. They have been invoked since the 1970s to explain the small masses of left-handed neutrinos that have been observed. While every other dark matter model postulates an entirely new particle, we don’t have to. This came as a big surprise,” he added.
As the mirror universe theory goes further in explaining things that inflation cannot, all scientific predictions will be tested in large-scale galaxy surveys like the Vera C. Rubin Observatory.
The largest LSST camera ever built for astrophysics, at 3,200 megapixels, it will soon help unlock the mysteries of the universe by taking detailed images of the Southern Hemisphere sky for 10 years, creating the most comprehensive view of our universe we have ever seen.
“Getting the camera to the top was the last major piece to the puzzle. With all of Rubin’s components physically in place, we are on the doorstep to transformative science with LSST,” enthused Victor Krabbendam, who is a project manager for the Rubin Observatory.
The Rubin Observatory, with their 3200 megapixel LSST camera, the largest ever built, is on its way to find evidence of the existence of the multiverse
Image credits: VERA C. RUBIN Observatory
Image credits: VERA C. RUBIN Observatory
Image credits: ESA Hubble
Modern physics, including quantum theory and cosmology, suggests several theories about how our universe might be just one of many. All of them lack evidence or proof to date, but it seems that very soon the situation will change.
Thanks to the Vera C. Rubin Observatory and their largest digital camera ever built, we may discover that we live in an entire ocean of other universes.
People on the Internet were abuzz with news of the possibility of the existence of the multiverse
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