Multiverse theory

 Multiverse

What is Multiverse :

The multiverse is a hypothetical collection consisting of several universes, including our own. Together these universes constitute the entire existence. The idea of ​​multiple existences stems from some scientific theories that eventually concluded that there must be more than one universe. This is usually the result of trying to explain the basic mathematics of quantum theory and understanding the multiverse. The multiple universes in the multiverse are sometimes called "parallel universes." The structure of the multiverse, the nature of each universe and what it contains, and the relationship between these universes depend on the theory followed, and there are several different theories in this regard.

How did the theory start :

In 1954, doctoral student Hugh Everett at Princeton University discovered an innovative idea: the existence of universes parallel to our own. All these universes are connected to each other, as we are branches of other universes and so are they.

In these parallel universes, the endings of our wars are different from what we know. Extinct species in our universe have evolved and adapted in other universes, and perhaps we humans are among the extinct species in those universes.

This kind of thinking is mind-boggling, yet still incomprehensible. Ideas about parallel universes or dimensions similar to our own have appeared in works of science fiction, but why would a young physicist risk his career by proposing a theory of parallel universes?

By presenting a hypothesis about parallel universes, Everett was trying to answer a difficult question related to quantum physics: Why do quantum objects behave uncontrollably? The quantum level is the smallest thing that science has discovered so far. The study of quantum physics began in 1900, when scientist Max Planck first introduced this concept to the scientific community. Planck's studies of radiation have led to some discoveries that contradict the laws of classical physics. These discoveries indicate the existence of different laws in this universe, operating at deeper levels than the laws we know.

In the short term, physicists studying the quantum level noticed strange things about this world. First, molecules at this level take on randomly different shapes. For example, scientists have observed that photons (small packets of light) behave as particles and as waves! Even a single photon makes this alternation of state. Imagine that you appear and act like a solid human being who has turned into a disgrace

Heisenberg's Uncertainty Principle states that when we observe quantum matter, we affect its behavior. Thus, we cannot be completely sure about the nature of a quantum object nor its distinct properties such as speed and location.

This idea is supported by the Copenhagen interpretation of quantum mechanics. The Danish physicist Niels Bohr suggested that quantum particles do not exist in one state or another, but in all possible states at the same time. The total sum of states of a quantum object is called the wave function. The state of something existing in all its possible states at the same time is called superposition.

According to Bohr, when we observe a quantum object, we influence its behavior. The observation breaks the supermode state of the object and forces it to choose one state of its wave function. This theory explains why physicists get conflicting measurements of the same quantum object: the quantum object chooses different states during successive measurements.

Bohr's interpretation has been widely accepted and has retained the acceptance of the majority of the quantum scientist community. But after a while, Everett's many-worlds hypothesis received some serious attention.

Multiverse in the many worlds theory :

Young Hugh Everett agreed to the proposal of the great physicist Niels Bohr about the quantum world. He accepted the idea of ​​the supermode and the wave function. However, Everett disagreed with Burr on another vital point.

For Everett, measuring something quantitatively does not force him to assume a certain state. Instead, measuring something quantum leads to a real bifurcation of the universe. The entire universe is replicated into two universes, and each universe represents a possible outcome of a measurement. For example, suppose the wave function of an object is both a particle and a wave. When a physicist measures this object, there are two possible outcomes: either the object is observed as a particle or as a wave.

When a physicist observes something, the universe splits into two universes to satisfy both possibilities. Thus, in one universe, the physicist discovered that something could be measured as a wave. While in the other universe, a similar physicist measured something as a particle. This also explains why something is measured in more than one state.

This difference is what makes Everett's many-worlds theory competitive with the Copenhagen interpretation, as both are interpretations of quantum mechanics.

Although it may sound exciting, Everett's many-worlds theory has implications beyond the quantum level. If an event has more than one possible outcome, then - if Everett's theory is correct - the universe will split when that event occurs. This actually happens even if the individual chooses not to take any action.

This means that if you are faced with a situation where death is a possible outcome, then in a universe parallel to our own, you are dead. This is just one of the reasons why some people feel uncomfortable with the many-worlds theory.

Another troubling aspect of the parallel worlds interpretation is that it threatens our linear concept of time. Suppose we have a timeline depicting the history of the Vietnam War. Instead of a straight timeline showing important events and their progress, the multi-world timeline branches off to show all the possible outcomes of each event. Therefore, there will be possible dates for each outcome of the event.

However, a person cannot be aware of the existence of their other twins - or even their death - in parallel universes. How do we know if the many-worlds theory is true? The possibility of this theory was theoretically confirmed in the 1990s by a thought experiment called quantum suicide.

This thought experiment revived interest in Everett's theory, which had long been considered nonsense. Since the existence of multiple worlds has been proven, the interest of physicists and mathematicians has been focused on studying the content of this theory in depth. However, the many-worlds theory is not the only theory that attempts to explain the universe, nor is it the only one that proposes the existence of universes parallel to our own. In the next part, we will learn about string theory and we may also find parallels with ourselves in parallel universes.