The Multiverse: A New Understanding [The Great Silence and the Structure of Reality]

Light is invisible, and invisibility is one of its most understandable properties. We see it only then, when it strikes the retina of our eye. And yes, we cannot see light that just passes right by, without reflecting off anything. Imagine an empty, dust-free, absolutely sterile room, never ending in all directions, so that before concluding the experiment, light does not have time to reach the walls and return. Or rather, the walls of the room should be matte black to completely absorb the light. Now, just imagine you are observing a flashlight from the side that is turned on. Wonderful. No, it's not exactly like that. You won't see the flashlight, neither the flashlight itself, nor the light that it emits. It's counterintuitive, but light is invisible. We cannot see it from the side when it's not reflecting off anything. If there were a reflective object in the beam of light, or even dust or water droplets to diffuse the light, we would be able to see it. But since there is nothing in the way of the light beam, and we are looking at it from the side, its light does not reach us. If there was a second light source in the room, then we would be able to see the flashlight, but not the light it emits. Beams of light, no matter how intense they are, even those that we can develop with a laser, just pass through each other, as if there was nothing at all in their path. These insights are contained in the book The Structure of Reality by the British physicist and philosopher David Deutsch, one of the creators of the concept of quantum computing. The book as a whole graphically demonstrates that the era of great philosophical systems is by no means a thing of the past. The author sets forth a comprehensive answer, consistent with scientific knowledge, to one of the most fundamental philosophical questions – what is the true nature of reality? And today we will try to make sense of it. To an observer who is in the beam of light and moving away backwards from the flashlight, the flashlight's reflector would appear even smaller, and when it would be visible only as a point, even fainter. The question then arises – can light really travel indefinitely in ever thinner beams? No. At a distance of about 10,000 km from the flashlight, its light would be too weak for the human eye to distinguish. The observer would not see anything. In other words, a person would not see anything, but an animal with more sensitive vision would. Take, for example, a frog, whose eyes are several times more sensitive than human eyes. This is quite enough to perceive a noticeable difference when conducting the experiment. If the observer was a physicist frog and it was moving away from the electric flashlight, the moment it completely loses sight of it would never come. Instead, the frog would see the flashlight begin to twinkle. The twinkles would occur at irregular intervals, which would increase as the frog moved away from the flashlight. But the individual flashes would not become less bright. At a distance of 100 million km from the flashlight, the frog would see on average only one flash of light per day, but this flash would be no less bright than any other observed from any other distance. Unfortunately, we don't know the language of frogs, which means that we won't be having scientific discussions with them. Therefore, when conducting genuine experiments, researchers use photomultipliers. These are light detectors, the sensitivity of which exceeds the sensitivity of a frog's eye and which reduces the light by passing it through dark filters. After all, observing light at a distance of 100 million km from its source is slightly problematic. However, neither the principle nor the result changes from this. Not the illusory darkness, not the unwavering faintness, but the twinkle, the flashes are of equal brightness, no matter how dark a filter we use. This twinkle proves that there is a limit to the uniform propagation of light. Each flash is caused by a photon hitting the retina. A beam of light becomes weaker not because the photons themselves become weaker, but because they drift apart from each other and the empty space between them expands. And this means the light becomes too weak to have an effect on the retina. This property of light, to appear merely in the form of particles of discrete sizes, is called quantization, and the individual particle of light, the photon, is called quantum of light. The quantum theory, as it so happens, got its name precisely because this property is attributed to all measurable physical quantities. Yes, everything that surrounds us and seems solid, in fact, is not. There is a world of diverse phenomena in quantum physics and quantization is one of the most elementary. But let's get back to our photons. You, of course, have heard about Thomas Young's double-slit experiment more than once. This experiment belongs to the general class of double-path experiments in which an initial wave is split into two separate waves that later again combine into a single wave. Changes in the path lengths of both waves result in a phase shift creating an interference pattern. Young's experiment is a classic illustration of the fallacy of theories that consider light solely as a stream of particles. If photons would display the properties of particles exclusively, then there would be two brightly lit areas on the screen behind the slits and a dark area between them. Thanks to Young's experiment, physicists were obligated to take the wave properties of light into account. This means that each real photon has to be accompanied by at least a trillion shadow photons. In general, the theory of the existence of multiverses is not very popular among physicists. Perhaps due to disagreements between theoretical physicists, the traditional starting point has been the quantum theory itself. And this is just one of the explanations, the interpretations of this experiment, bringing us closer to something new, parting the veil into the fascinating and astonishing quantum world.