Physicists think we may live in a multiverse—one where there are many universes besides our own. But how can we tell if that’s true? Astrophysicist and physicist Adam Becker explores four ways to find out if we do indeed live in a multiverse, and if so, what it means for us and the universe at large.
1)The Cosmic Microwave Background Radiation
One way scientists have of exploring the possibility of a multiverse is by studying the Cosmic Microwave Background Radiation (CMBR). The CMBR is the afterglow of the Big Bang, and it should look the same in every direction we look. However, if there are other universes out there, they could be affecting the CMBR. In 2016, NASA researchers announced that they had found an unusual pattern in the data from space which might suggest that there’s something else going on: namely that our universe may exist inside of a higher-dimensional structure called the cosmic web. According to this theory, each point in the fabric has its own separate reality.
A team of physicists at Durham University claimed earlier this year that their calculations support the idea that our Universe sits within a three-dimensional multiverse. Their research examined what happened just moments after the Big Bang – when quantum effects would have been strong enough for quantum tunneling to occur across multiple domains and universes. The scientists took into account the effect of gravity on protons and neutrons in the primordial soup created by the Big Bang. They found that these particles may not have interacted with all possible particles because gravity only stretches so far, before pulling everything back together again. With these constraints, they were able to calculate how many possible universes we could inhabit. When extrapolated to billions of years, the model suggests that there are around 10^22 different physical realities. That’s roughly 10 trillion times as many as we’d previously calculated. If you take into account things like quarks, electrons and photons, then the number increases dramatically to around 10^10^122 different universes. We’ve found evidence for a multi-verse, said Dr Roumen Mladjov, one of the lead authors on the paper. The probability that these results come about by chance is infinitesimally small. The next step, he says, will be to figure out why there appears to be some sort of separation between domains or universes.
2) Gravitational Lensing
One way scientists have been able to infer the existence of other universes is through gravitational lensing. This is when the gravity of a massive object warps the space around it, causing light from objects behind it to bend and appear distorted. By studying these distortions, scientists can learn about the mass and structure of the object doing the lensing, and sometimes even infer the presence of other objects that we can’t see directly. In this way, the distortion of space caused by dark matter was first detected. Theoretical physicist Erik Verlinde has argued that this effect could come from our universe folding into itself in some places because of dark energy, which would produce an infinite number of universes inside each other like Russian nesting dolls. There’s also what’s called cosmic inflation, where the early universe goes through a period of rapid expansion before slowing down again. That period of expansion means there were more collisions between particles, leading to more variety among them. So if there’s another universe just like ours with everything exactly the same but for one tiny difference—say two electrons spinning in opposite directions—that difference will be magnified over time, leading to two universes that are almost identical but for that one key difference.
Some physicists believe that different parts of the universe started out with different values for their physical constants, so they evolved differently and eventually became separate universes. If you believe this theory, then all life forms throughout the multiverse developed at different rates depending on their location within a given universe. Even more radical theories propose that parallel universes exist in infinitesimally small points of space or string theory proposes that every particle might actually be its own universe; but no evidence yet exists to prove those hypotheses.
3) Quantum Universe and Holographic Principle
Some scientists believe that our universe is just one of an infinite number of universes, making up the so-called multiverse. There’s evidence to support this idea, which comes from theories like the quantum universe and the holographic principle. The Quantum Universe Theory says that every time we make a decision about what to do, for example which way to turn at an intersection, the world splits into two separate worlds.
It doesn’t stop there either; each new choice then causes another branch off into two more different worlds, with no end in sight! The Holographic Principle says that instead of inhabiting three dimensions with height, width and depth (x, y and z), we only inhabit 2D space with length and width (x and y). Imagine cutting out a piece of paper and flattening it out to get the best approximation of how holograms work: you can see the entire image when looking at it from any angle. That’s because even though the paper appears flat on the table, it’s actually being projected onto a 3D surface—in this case, your computer screen. The same goes for holograms: they appear as 2D projections on a 3D surface.
4) Dark Matter / Dark Energy
Dark matter and dark energy make up the majority of the universe, and we still don’t know what they are. One theory is that we live in a multiverse, where our universe is just one of many. Here are four ways to see the evidence for this theory #1-The Super Mario Universe: Our world has laws, but Mario doesn’t follow them. Maybe he lives in a different universe with different laws-which means he lives in another multiverse. #2-The Color Spectrum: Scientists often divide light into rainbow colors like red, orange, yellow, green blue and violet (ROYGBIV). But it’s not possible to go on forever because there is always black between every color! In other words, we can never reach an endpoint of all the visible light waves on Earth.
Since the visible spectrum is infinite, some scientists believe that there must be an infinite number of universes out there-each with their own ROYGBIV spectrum. #3- Cosmic Microwave Background Radiation: The cosmic microwave background radiation is made up of leftovers from when our universe was born. Some say that if you combine this type of radiation data with the fact that we exist, then there may have been more than one time our universe began. That would mean we live in a multiverse! #4-Faster Than Light Travel: Einstein’s Theory of Relativity states that nothing can travel faster than light. If this were true, then everything would need to move at roughly the same speed and anything moving faster than light would cause issues for those around it.
