Faced with new evidence, physicists are beginning to see the universe not as a collection of disparate layers, but instead as a single quantum entity connected by quantum entanglement.
Understanding the Universe Through Dividing Reality
Physicists’ interpretation of the universe relies on breaking everything down into its constituent parts, a process known as reductionism. As a particle physicist, I was raised on this philosophy. Physics has taken us far – it is how we build our current picture of matter and its workings. But now, with further progress stalled, I am convinced that we need to do things differently from here.
Expanding the View
Rather than zooming in closer and closer, I believe we need to zoom out. In doing so, we may see that everything there, including fundamental things like space and time, breaks from a unified whole. This may sound like philosophy or mysticism, but it is actually a direct result of applying quantum mechanics to the entire universe. When you do that, you realize that the universe is not essentially made of separate parts at all; instead, it is one quantum entity.
Experimental Evidence
It’s a radical idea, and we are just beginning to experimentally test it. But if it is correct, it may help resolve some of the most exciting puzzles in physics and upend our way of thinking about the universe.
The Crisis in Particle Physics
For nearly a century, physicists have been trying to understand the more fundamental layers of reality without knowing what happens inside them. In the 1930s, when Enrico Fermi was working to understand how a neutron decays into a proton and emits an electron – known as beta decay – he did so only by looking at the electrons, protons, and neutrons involved. It was only decades later, when physicists discovered an intermediary particle called the W particle, that they realized there was a deeper layer of interactions happening at smaller scales.
Effective Field Theory
Effective Field Theory (EFT) is a name given to any work that exploits this idea. When physicists want to describe effects that go beyond an established but incomplete theory, without specifying what the new physics is, they use EFTs. “Everything is an EFT,” says Cliff Burgess, a physicist at McMaster University in Hamilton, Canada, who has written a book about this approach.
Issues with Effective Field Theory
One of the puzzling issues that theoretical physicists have grappled with for years involves the Higgs particle, which is responsible for giving mass to quarks and electrons. In theories like the standard model, particles can briefly transform into short-lived entities known as virtual particles, which then quickly decay back into the original particle. In the strange quantum way rules governing the particle world, these fluctuations contribute to the mass of the particle. The extent of this contribution depends on the highest energy that the virtual particles can reach.
The Fine-Tuning Problem
To solve this conundrum, calculating the contributions to the mass of the particle relies on the energy limits applicable to the standard model – or the size of a Russian doll. As far as we know, the upper limit of energy is the Planck scale, the smallest scale existing where gravitational effects become significant, and the standard model must be replaced by something that unifies gravity and quantum mechanics. According to this idea, the mass of the Higgs particle is expected to set the Planck scale. But the forecast is that it exceeds by 17 orders of magnitude the actual mass measured when the particle was discovered at the LHC.
The Only Solution
The only way to overcome this conundrum is to accept that the largely unrelated contributions to the Higgs mass from transient virtual particles happen almost by chance to cancel each other out perfectly. This makes the conditions we observe in our universe as improbable as a pencil balancing on its tip. This is known as the fine-tuning problem.
The Crisis
Particle Physics
A similar puzzle appears in cosmology. This puzzle concerns dark energy, the mysterious force that drives the accelerated expansion of the universe. It is believed that the expansion is caused by energy stored in the vacuum of space. However, here our observed reality differs more from expectations: the value of the vacuum energy we measure is extremely small, by about 30 orders of magnitude compared to mass. A crisis in particle physics.
Attempts to Solve the Puzzles
There are some attempts to solve these two puzzles. For example, the theory of supersymmetry predicts the existence of new particles that cancel out the quantum fluctuations produced by Standard Model particles. Alternative solutions suggest additional dimensions of spacetime. This idea—proposed by Nima Arkani-Hamed, now at the Institute for Advanced Study in Princeton, New Jersey, and his colleagues—suggests that gravity may leak into these additional dimensions, making it appear weaker than it actually is. Models based on this idea predict a lower Planck scale, meaning a smaller Higgs mass. The additional dimensions are invisible because they are tightly wrapped, so they have escaped experimental detection so far.
Particle Physics in Crisis
In short, particle physics is in crisis. This is why a small group of theorists, including myself, has begun to explore another radical approach—proposing an alternative to reductionism as we know it. Rather than treating the different energy levels of the universe separately, it treats them as if they have some effect on each other.
Understanding Our Universe Through the Partitioning of Reality
To understand how this works, consider an analogy used by physicists that invokes boundaries where rainbow colors become invisible. At the highest energies, thus the smallest sizes, after violet in the rainbow is what we call ultraviolet (UV). At the lowest energies and largest sizes, you have what we call infrared (IR). Between the two, in the visible part of the rainbow, is the realm in which the Standard Model operates.
More Research
For a long time, there hasn’t been much interest in this outcome. Most people were focused on supersymmetry and its potential to solve the Higgs particle problem. But recently, the crisis in physics has become more apparent as viable solutions to the fine-tuning problem have declined. As a result, Cohen’s and his colleagues’ theories began to receive significant attention from theorists like myself. I started to wonder: if the interplay between ultraviolet and infrared could help solve the dark energy problem, could it also assist in addressing the other major secondary issue in fundamental physics, which is the lightness of the Higgs particle?
Quantum Entanglement
Quantum entanglement is typically described as a remarkable correlation between quantum objects. Prepare two particles in a certain way and the measurement of one instantaneously determines the other, no matter the distance between them. However, these correlations can be thought of as evidence that entangled quantum systems cannot be understood as being made of parts: they are one indivisible whole. Just as this indivisibility links distant particles, it can also link quantum effects at different energies. In other words, quantum entanglement may be responsible for the UV and IR scales of the universe that seem to communicate with each other.
Entangled Effects
As we move up the size scale and down the energy scale, lower energy effects can be disrupted by a process called scattering. This well-understood quantum phenomenon hides the entanglement from the local observer’s view. It’s the reason we do not experience any quantum weirdness in our daily lives.
Entanglement and Interference
Some research has found a relationship between entanglement and the interplay between ultraviolet and infrared, but the boundaries in Cohen’s and his colleagues’ study were attributed to gravity rather than entanglement. Impressively, recent research conducted by some leading researchers in string theory offers a solution: by suggesting that gravity itself may be a disguised form of entanglement.
Effects
Entanglement in the Universe
If we are to infer support for this idea, it would radically change the way we understand the universe. It would mean that we would not only see a world in a grain of sand, as the poet William Blake said, but we might literally see the entire universe in its smallest pieces and particles. And while this may seem just a different way of dealing with physics, it is much more than that. I believe we are on our way to a completely new understanding of how the universe is formed.
Heinrich Bass is a theoretical physicist at Dortmund University of Technology in Germany and the author of the book “Everything is One”.
Learn more about the secrets of the universe. Visit the Universe Theatre at New Scientist Live in October 2023 newscientistlive.com
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