The mystery of gravity can prove that our multiverse exists

At first, the universe was nothing. In the quantum interpretation of nature, however, even nothing is anything. It's potential – specifically, it's the potential to exist. The fact that nothing fulfills this potential depends on the probability. Chances are nothing will come to nothing. But nothing could beat the odds and do anything. If this is the case, the result will be enter into existence.

This result is not a mathematical trick, a theoretical possibility that is not a necessity. As Einstein concluded – this long-standing equivocator on the existence of black holes – at a conference in Oxford in 1933, "the experiment remains, of course, the sole criterion of the physical unit of a mathematical construction ". Not that you have to see it to believe it, but if you see it, you have to believe it.

And many physicists had seen it. Not directly, but in the most indirect way possible, as convincing as possible of modern physics. In 1948, Dutch physicist Hendrik Casimir predicted that virtual particles would leave traces of energy. Place two parallel plate leads closer together and you can measure the increase in vacuum energy. Many experiences over the following decades validated the existence of the "Casimir effect".

As strange as it is – "in a tone of fear and reverence" was the advice of a mathematician on how to approach the phenomenon – the Casimir effect has a special significance for gravity. According to the general theory, energy interacts with gravity. And the Casimir effect shows that virtual particles have energy. Therefore, virtual particles, fragments of nothing that have managed to beat the odds and become something, interact with gravity.

In the late 1970s and early 1980s, several theorists began to explore the possible consequences of this relationship on a cosmological scale. What they found in the calculations is that a billion billion billions of seconds after the creation of the universe, space went through an "inflationary" phase that multiplied by a trillion times. What they also found in the calculations is that if the universe was born of a quantum pop – a nothing that became something – this pop would almost inevitably have created other pops. And those other sudden things, just like something that would become our universe, would become from other universes. The most common mathematical interpretation placed the number of such universes, before the self-replicating mechanism stopped, at 10⁵⁰⁰ – a follow-up of 500 zeros. *

If the inflation scenario was a valid interpretation, then maybe the gravity is so aberrant that it may belong to a different universe, as it is. Theorists have proposed, for example, that gravity can be something that enters our universe from an adjacent universe, or that it is an artifact of a colliding universe. Whatever the merits of individual theories on other universes, the idea of ​​a multiverse as an explanation of the aberrant status of gravitation has made it possible to move from one unusual system to another in one generation.

The global concept has been called the anthropic principle. anthropogenic means "pertaining to the existence of humans", and the principle, at least as far as cosmology is concerned, is that we can look at the universe because we live in a universe that we can examine.

The logic was not as tautological as it may seem. In a multiverse, each universe would have its own laws of physics. A universe in which, for example, gravitation is not lower than a factor of about one billion trillion trillions of trillions of trillions of trillions of people is a universe that would not be conducive to the existence of the human spirit. Or the existence of galaxies, from elsewhere.

Yet we are there. What are the chances?

One in 10⁵⁰⁰?

Edwin Hubble wrote: "The history of astronomy is a story of receding horizons." The spheres of Aristotle define our most distant vision; then the Galileo congestions of stars in our galaxy; then the congeries of Hubble galaxies; then superclusters of galaxies, all suspended by a thread of dark matter; then a web of wires escaping from the breath of black energy. Why do not from other universes?

If you have attended conferences and symposia on cosmology in the early 21st century, you have certainly attended a PowerPoint presentation (or more likely an overhead projector) on this topic. I've already seen a theorist pronounce a thunderous anti-anthropic conference at a symposium at the Space Science Telescope Institute, on the campus of Johns University. Hopkins. Two or three years later, I found his signature over an essay in Science magazine in which he and a co-author claimed that the human principle deserved to be explored.

The essay first recounted the type of anti-anthropological reasoning he had exposed at this conference in Baltimore: "The potential existence of a set of unobservable universes seems to be in conflict with the" scientific method "(which requires that theories be falsifiable by observations or experiments) and therefore in the field of metaphysics". Now, however, he wanted to make a distinction – a "fuzzy" border "between what we define as observable and what is not." We do not see dark matter or dark energy, but we know something is there. We do not see gravity, but we know that something is there. You do not have to see it to believe it, so what you can see leaves you with little or no alternative. In the case of human reasoning, the determining factor was the strength or lack of gravity: "If gravity was not so low, there would not be such a big difference between the scales mass, length and time of the atom and the cosmic ".

The next time I saw him at a conference, I stopped him in a hallway, I said that I had read his essay and reminded him of the speech I had attended. Then I said, "What happened?"

He shrugged. facts was what happened. "The proof," he said. The successors of the radio telescope which, in 1965, detected the cosmic microwave background noise continued to refine our vision of the first universe: the cosmic background explorer in the early 1990s, the microwave anisotropy probe. Wilkinson of the next decade, decade after that. By studying quantum fluctuations in the primordial universe, physicists had quantified the distribution of matter and energy that existed then – and the laws of conservation being what they are, it is present now. These fluctuations revealed a universe composed of 68.3% dark energy, 26.8% dark matter and 4.9% ordinary matter (protons, neutrons, etc., as we l & rsquo; had always assumed, the universe as a whole). To simplify the presentation, these figures included rounding errors, but if you have explored quantum quantifications well, the universe that emerged was in almost frightening equilibrium. Dark energy, for example, had the precise density of Planck – a quantum measure used by physicists – of a decimal point followed by 122 zeros, then the number 136. If the value was even slightly different, our universe would not would not exist. any recognizable form. If, for example, the value was a decimal point followed by 122 zeros and the number 137, the galaxies would not have formed. Yet they did it like us.

This balance, which is otherwise inexplicable, he said, left him little choice: "It is very difficult not to have multiverse." We live in a universe in which gravity is extraordinarily weak, because it is the only type of universe from which we could be born.

Excerpt from THE TROUBLE WITH GRAVITY by Richard Panek. Copyright © 2019 by Richard Panek. Reprinted with permission of Houghton Mifflin Harcourt Books and Media. All rights reserved.