Hugh Everett III, a doctoral student at Princeton University, proposed a groundbreaking concept in 1954: the existence of a parallel universe mirroring our own. This idea suggests a interconnected network of multiple universes branching from, and contributing to, our own. These alternate universes could contain vastly different realities. Perhaps wars unfolded with different results, or extinct species thrived and evolved.
It’s even possible that humanity met its demise in some of these parallel worlds which some theories take further to suggest infinite universes teeming with infinite possibilities. While the concept of parallel universes, often explored in science fiction and metaphysical explanations, is intellectually stimulating, it raises the question of why a promising young physicist would jeopardize his career with such a radical theory.
Everett’s Many-Worlds theory was an attempt to resolve a perplexing problem in quantum physics: the seemingly erratic behavior of quantum matter.
Quantum physics, the study of the universe’s smallest known level, originated in 1900 with Max Planck’s introduction of the concept. Planck’s research on radiation revealed peculiar results that clashed with established principles of classical physics.
These results implied the existence of a deeper layer of universal laws, operating beyond our conventional understanding.
Heisenberg Uncertainty Principle – Very quickly, quantum physicists discovered unusual properties in the subatomic realm. One such oddity is the ability of particles at this level to spontaneously adopt different forms. For instance, photons, the fundamental units of light, have been observed behaving as both particles and waves, a phenomenon exhibited even by a single photon.
To illustrate, consider a scenario where you appear as a solid person when someone looks at you, but transform into a gaseous form when they look away. This is a simplified analogy of the Heisenberg Uncertainty Principle.
Werner Heisenberg proposed that the very act of observing quantum matter influences its behavior. Consequently, we can never definitively know the true nature of a quantum object or its properties, such as velocity and position.
Copenhagen Interpretation of Quantum Mechanics – The Copenhagen interpretation of quantum mechanics, championed by Niels Bohr, provides a framework for understanding this concept. It posits that quantum particles exist in a multitude of potential states simultaneously, rather than settling on a single, definitive state.
This collection of all possible states is described mathematically as the wave function, and the existence of an object in all of these states at once is termed superposition. Bohr argued that the act of observing a quantum object fundamentally alters its behavior. This observation disrupts the object’s superposition, effectively compelling it to select a single state from its wave function. This theory explains the varying measurements obtained from the same quantum object, as it “chooses” different states during each measurement.
While the Copenhagen interpretation has been widely accepted within the quantum physics community and continues to be so, Everett’s Many-Worlds interpretation has recently gained significant traction as an alternative perspective.
Many-worlds Theory – While the renowned physicist Niels Bohr’s ideas about quantum mechanics resonated with the young Hugh Everett, particularly regarding superposition and wave functions, Everett fundamentally disagreed with Bohr’s assertion that measurement forces a quantum object into a single, definitive state.
Instead, Everett proposed that a measurement of a quantum object triggers a literal split in the universe, creating a new universe for each potential measurement outcome.
For example, if an object exists in a superposition of both particle and wave states, a physicist’s measurement will result in two distinct universes: one where the object is observed as a particle and another where it’s observed as a wave. This concept positions Everett’s Many-Worlds interpretation as a competing explanation to the Copenhagen interpretation of quantum mechanics. This also provides an explanation for how a single particle can appear to exist in multiple states.
The unsettling implication of Everett’s Many-Worlds interpretation extends beyond the quantum realm. If an action has multiple possible outcomes, the universe, according to this theory, splits each time that action occurs, even when the action is to do nothing.
Consequently, if you’ve ever been in a life-threatening situation, a parallel universe exists where you died, a notion that many find deeply disturbing.
Another unsettling aspect is the challenge it poses to our linear understanding of time. A timeline of an event like the Vietnam War, viewed through the lens of Many-Worlds, would branch out infinitely, depicting every possible outcome of every action, resulting in an endless array of alternate universes.
However, individuals cannot perceive their alternate selves or experiences, including their deaths, in these parallel universes. This raises the question: how can we verify the Many-Worlds theory? A theoretical validation emerged in the late 1990s through a thought experiment known as quantum suicide.
This thought experiment reignited interest in Everett’s theory, which had initially been dismissed by many. With its theoretical possibility established, physicists and mathematicians have since focused on exploring the implications of the Many-Worlds interpretation. However, it’s important to note that this is just one theory explaining the universe and postulating the existence of parallel universes. String theory is another such theory, which we will explore further.
Differing Opinions on Parallel Universes – The Many-Worlds theory and the Copenhagen interpretation are not the only contenders in the quest to understand the fundamental nature of the universe. In fact, physics as a whole, not just quantum mechanics, is home to numerous theories attempting to explain this basic level.
Just as in psychology, where theories proposed by Carl Jung, Albert Ellis, and Sigmund Freud have their proponents and critics, the same is true in the field of subatomic physics. The theories that have emerged from this study are still unproven and remain a subject of debate.
Physicists have been working their way backward from the observable universe to smaller and smaller levels of the physical world in an attempt to understand the most fundamental level of the universe. This level is believed to serve as the foundation for understanding everything else.
After developing his theory of relativity, Albert Einstein spent the rest of his life searching for a single, final level that would answer all physical questions. This elusive theory is referred to as the Theory of Everything, and while quantum physicists believe they are getting closer to finding it, other physicists look to a theoretical subquantum level called string theory for the answers to life’s biggest questions.
Interestingly, these physicists have also concluded through their theoretical investigations that there are parallel universes, just as Hugh Everett had suggested.
Where String Theory Comes In – Developed by Japanese-American physicist Michio Kaku, string theory proposes that the fundamental components of both matter and the universe’s physical forces, including gravity, reside at a sub-quantum level. These elementary building blocks are conceptualized as minuscule, vibrating strings, analogous to tiny rubber bands, which constitute quarks (quantum particles) and subsequently, electrons, atoms, cells, and all other forms of matter. The specific type of matter created and its behavior are determined by the vibrational pattern of these strings. This framework suggests that our entire universe is constructed in this manner, spanning across 11 distinct dimensions.
Similar to the Many-Worlds interpretation, string theory posits the existence of parallel universes, envisioning our own universe as a bubble coexisting alongside similar, parallel realms. However, in contrast to the strictly separate nature of universes in the Many-Worlds theory, string theory proposes potential interactions between these universes, specifically through the flow of gravity. These interactions, according to the theory, can trigger Big Bang events, akin to the one that birthed our own universe.
Despite advancements in detecting quantum matter, the sub-quantum strings remain unobserved, rendering them and the theory itself purely theoretical, subject to both skepticism and continued support.
While the Many-Worlds theory suggests an unknowable existence of parallel universes, string theory, despite a failed experimental test, continues to fuel the belief in parallel dimensions, as championed by Dr. Kaku.
Einstein, who sought a “Theory of Everything,” did not witness its pursuit by succeeding generations. Interestingly, the Many-Worlds theory suggests that Einstein may still be alive and well in a parallel universe, potentially one where physicists have already uncovered the elusive Theory of Everything.
