Hitting the Books: How to Reveal the True Nature of the Multiverse

IIt is difficult to describe the state of the affairs of the universe when everything has been compressed to a volume slightly smaller than the period at the end of this sentence – on account that the concepts of time and space literally do not yet apply. But that challenge hasn’t stopped theoretical astrophysicist Dr. Laura Mercini Hutton from pursuing knowledge at the edge of the known universe and beyond. In her new book, Before the Big BangMersini-Houghton recounts her early life in communist Albania, her career as she rose to prominence in the male-dominated field of astrophysics and discusses her research into the multiverse that could fundamentally rewrite our understanding of reality.

Before the Big Bang Cover

Mariner Books

Adapted from Before the Big Bang: The Origin of the Universe and Beyond by Laura Mercini Hutton. Published by Mariner Books. Copyright © 2022 by Laura Mersini-Houghton. All rights reserved.

Scientific investigations of problems such as the creation of the universe, which we cannot observe or reproduce and test in the laboratory, are similar to investigative work in that they rely on intuition as well as evidence. Like a detective, when pieces of a puzzle begin to fall into place, researchers can intuitively sense that the answer is close. This was the feeling I got as a rich man and tried to figure out how we could test our theory of the multiverse. Logically, it seemed like a long shot, but seemed intuitively achievable.

Finally, a potential solution hit me. I realized that the key to testing and validating this theory was hidden in quantum entanglement – because decoherence and entanglement were two sides of the same coin! I can trace the creation story back to its roots in the quantum landscape, when our wave universe was intertwined with others.

I already knew that the separation – the decoherence – of the branches of the wave function of the universe (which later became individual universes) was the result of their entanglement with the bath of environmental fluctuations. Now I wondered if we could calculate and find any traces of this early entanglement imprinted on our skies today.

This may seem like a contradiction. How can our universe remain intertwined with all other universes all these eons after the Big Bang? Our universe must have been separated from them in its quantum cradle. But as I grappled with these issues, I realized that it was possible that there was a universe that had long since been disengaged but also retained childish “scratches” – slight changes in shape caused by interactions with other surviving universes that were intertwined with during the first moments – Recognizable nevi. The scars of his initial entanglement should still be visible in our universe today.

The key was in timing. Our wave universe was disintegrating around the same time as the next phase, the particle universe was going through its own cosmic inflation and came into being. Everything we observe in our skies today is inspired by the primordial fluctuations that resulted from those first moments, occurring in the smallest measurable units of time, much less than a second. In principle, during those moments, when the entanglement was eliminated, it was possible to stamp his signatures on the blow and his swings. There was a possibility that the kind of scar I had imagined had formed within such a short period. And if they have, they should be visible in the sky.

Understanding how scars form from tangles is less complicated than you might imagine. I started by trying to create a mental picture of the tangle scars in our skies. I’ve imagined all the surviving universes of the universe’s wave function branches, including ours, where a bunch of particles scatter around the quantum multiverse. Since they all contain mass and energy, they interact with (pull) each other by gravity, just as the path of motion of Newton’s apple was curved by interacting with the mass of the Earth, thus directing it to the Earth. However, the moon, the sun, all the other planets in our solar system, and all the stars in the universe were also attracted to the apple. The Earth’s mass possesses the most powerful force, but this does not mean that these other forces do not exist. The final impact that entanglement has left in our skies is captured by the combined pull of our universe by other infant universes. Similar to weak clouds of stars on the famous apple, nowadays, the signs of entanglement in our universe are incredibly small compared to the signs of cosmic inflation. But they are still there!

I’ll admit it… I was excited just thinking that I might have a way to peek beyond our horizon and before the Big Bang! By proposing to calculate and track entanglement in our sky, I may have, for the first time, identified a method for testing the multiverse. What struck me most about this idea was its ability to make what we thought was impossible for centuries – an observational window to peek into space and time outside our universe into the multiverse. Our expanding universe provides the best cosmic lab for searching for information about its beginning because everything we observe on large scales in our universe today was also in its infancy. The basic elements of our universe do not disappear over time; They are simply re-measuring their size as the universe expands.

Which is why I thought of using quantum entanglement as a litmus test of our theory: Quantum theory contains a near-sacred principle known as “unity,” which states that no information about a system can ever be lost. Unity is a law of information preservation. This means that signs of early quantum entanglement of our universe with other surviving universes should remain to this day. Thus, despite the decoherence, entanglement cannot be erased from the memory of our universe; It is stored in its original DNA. Moreover, these signs have been encoded in our sky since its inception, since the universe began as a wave on Earth. The effects of this former entanglement will simply extend as the universe expands as the universe becomes a much larger version of its infant self.

I was worried that these signatures, stretched by inflation and the expansion of the universe, would be very weak. But on the basis of unity, I thought, however weak it was, it was preserved somewhere in our sky in the form of local violations or deviations from the uniformity and homogeneity predicted by cosmic inflation.

Rich and I decided to compute the effect of quantum entanglement on our universe to see if there were any traces left behind, then quickly brought them back from childhood to the present and deduced predictions of what kind of scars we should look for in our skies. If we can determine where we need to look, we can test it by comparing it with actual observations.

Rich and I began this investigation with the help of a physicist in Tokyo, Tomo Takahashi. I was first introduced to Tomoe at the University of North Carolina at Chapel Hill in 2004 when we nested together for one year. He was a postdoc about to take a faculty position in Japan, and I had just arrived at UNU. We enjoyed the interaction, and I saw the high standards that Tomoe maintained in his work and his superior attention to detail. I knew he was familiar with the computer simulation program we needed to compare predictions based on our theory with actual data about signatures of matter and radiation in the universe. In 2005, I contacted Tomoe and he agreed to cooperate with us.

Rich, Tomoe, and I decided that the best place to start research was at the CMB – the cosmic microwave background, the twilight from the Big Bang. CMB is the oldest light in the universe, a global “ether” that has permeated the entire universe throughout its history. As such, it contains a kind of exclusive record of the first millisecond in the life of the universe. And this silent testimony of creation is still around today, making it an invaluable cosmic laboratory.

The energy of CMB photons in our current universe is very low; Their frequencies peak around the microwave range (160 GHz), just like the photons in your kitchen microwave when you heat up your food. Three major international scientific experiments — the COBE, WMAP and Planck satellites (with a fourth on the way), dating from the 1990s to the present — have measured the CMB and its much weaker fluctuations to pinpoint accuracy. We even encounter CMB photons here on Earth. In fact, seeing and hearing CMB was a daily experience in the age of old TVs: when changing channels, the viewer would experience the CMB signal in a static form – the blurry, gray and white spots that appeared on the TV screen.

But if our universe started out of energy only, what can we see in the CMB photons that give us a nascent picture of the universe? Here, quantum theory, and specifically Heisenberg’s uncertainty principle, provides the answer. According to the uncertainty principle, quantitative uncertainty, which is presented as fluctuations in the initial energy of inflation, is inevitable. When the universe stops inflation, it is suddenly filled with waves of quantum fluctuations of inflation energy. The full range of fluctuations, some with mass and some without, is known as density perturbations. The shorter waves in this spectrum, those that fit the universe, become photons or particles, depending on their mass (reflecting the phenomenon of wave-particle duality).

Small vibrations in the fabric of the universe that cause weak ripples or vibrations in the gravitational field, known as primordial gravitational waves, contain information about the specific inflation model that occurred. They are incredibly small, at one part about ten billionths of the strength of the CMB radiation spectrum, and therefore difficult to observe. But it is saved in CMB.

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