Major Theories and Evidence Behind the Multiverse
Multiverse is a term coined on the pillar of multiple hypotheses. It falls under the broader subject known as cosmology and stands upon some theories. As per the historical aspects, the concept of the multiverse was mentioned in Greek Atomism. There it is termed as infinite worlds and universe. By middle age, it became more and more prominent. Apart from cosmology, multiverse universe concepts have been discussed in physics, astronomy, religious texts, and all types of literature. The scientific approach of the multiverse is discussed here in detail. Generally, the students of astrophysics have to study these concepts and the arguments.
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Multiple Universes: A Broader Aspect
In a broader aspect, you can term a multiverse as an infinite multiverse too. As per literature, these can be called parallel universes. These consist of all the abstract terms that define existence like time, space, energy, matter, and information. Each parallel universe also has constants and physical laws by which they can be defined mathematically.
Many scientists have so far worked on the quantum multiverse and searched for clear evidence of its presence. The most recent example can be of 2010 when Stephen N Feeny analyzed the data of the WMAP (Wilkinson Microwave Anisotropy Probe) and claimed that in the distant past, our universe might have collided with another universe.
However, the theory of the bubble universe collision was turned down by the findings of the Planck Satellite. Most scientists believed in that because the clarity of the satellite was three times better than the WMAP. The NASA multiverse research, however, is still on where the ANITA setup had come up with the claim in 2016, to have found a parallel universe where the time runs in a reverse direction.
Before 2016, most scientists did not believe in the multiverse theory as they could not detect any gravitational pull from other universes.
Types of Multiverses
As many scientists have been working on the concept of the multiverse, they have come up with a few types. Here are some details related to it. Generally, it depends on the degree to which the coexistence of a specific universe concerning one can be framed scientifically.
The Common Origin Model: In the case of the common origin model, multiple universes have a single origin. Moreover, they are considered to be interacting with each other.
The Disconnected Model: The disconnected model of the multiverse is proposed by some scientists which shows that the parallel universes have independent origins but they cop-exist easily with similar reality. This hypothesis fully stands with the support of the modal realism theory.
The Quantum Gravity Model: The quantum gravity model is yet another approach to prove the existence of a multiverse that is more connected to one another. This approach mainly stands on the general relativity theory of Albert Einstein and verses of quantum mechanics.
While giving a base to the multiverse concept, this approach shows that a big bang that leads to the creation of the universe can be the reason for its expansion too. These expansions can lead a baby universe to take the shape of a tree where one universe might not be able to interact with the other.
As per almost all scientists, the big bang occurs mostly in the interiors of the black holes and that is where a new universe can form (literally from the ashes of a pre-existing universe).
Arguments Against the Multiverse Theory
There are a lot of arguments against the multiverse theories from experts belonging to different fields like physics and philosophy. In most cases, philosophists do not count the multiverses that are of the disconnected type, and given the subject, it is legitimate.
In the case of science, most scientists fail to frame the real multiverse meaning as they are still unaware of the reality of life and how it can be framed under the context of the multiverse. Moreover, the basic theory of the cosmological constant falls short when it comes to proving the presence of multiverses.
The outcomes of the Planck Satellite also show that there are no attractions from other bubble universes. The scientists believe that it should have occurred in case of the presence of a multiverse near our solar system.
Fun Facts About Multiverse
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As per quantum mechanics, there is a multiple-world interpretation where our world can split according to every minute quantum event occurring in every second. So, even our world can be changed into a multiverse.
FAQs on What Is the Multiverse in Physics?
1. What is the basic concept of the multiverse in theoretical physics?
In theoretical physics, the multiverse is a hypothetical collection of multiple, potentially infinite, universes, including our own. This concept suggests that our universe is just one of many existing in parallel, each potentially with its own unique properties, physical laws, or even different timelines. These universes are collectively known as the multiverse and are thought to arise from various cosmological and quantum theories.
2. Is there any scientific proof that the multiverse exists?
No, there is currently no direct observational or experimental evidence to prove the existence of the multiverse. It remains a hypothetical concept derived from theories like string theory and cosmic inflation. The primary challenge is that other universes are, by definition, causally disconnected from our own, making them extremely difficult, if not impossible, to detect or test with current technology.
3. What are some of the main types of multiverse theories proposed by physicists?
Physicists have proposed several models for the multiverse, each based on different principles. Some of the most discussed types include:
- Inflationary (or Bubble) Universe: Suggests that our universe is one of many 'bubbles' that formed and expanded after a larger cosmic inflation event.
- Many-Worlds Interpretation: A concept from quantum mechanics where every quantum event creates branching universes, representing every possible outcome.
- Brane Multiverse: Arising from string theory, this model posits that our universe exists on a membrane, or 'brane', floating in a higher-dimensional space, with other branes (universes) potentially existing nearby.
- Holographic Multiverse: Proposes that our 3D universe is a holographic projection of information stored on a distant 2D surface.
4. How does the theory of cosmic inflation lead to the idea of a multiverse?
The theory of cosmic inflation describes a rapid expansion of space just after the Big Bang. The 'eternal inflation' model suggests this process might not have stopped everywhere at the same time. While inflation ended in our observable universe, it could still be ongoing in other regions of space. Each region where inflation stops could become a new 'bubble universe' with its own Big Bang, leading to a vast, ever-growing collection of universes, thus forming an inflationary multiverse.
5. What is the difference between the 'Many-Worlds Interpretation' and the 'Bubble Universe' theory?
The primary difference lies in their origin and nature. The 'Many-Worlds Interpretation' is a product of quantum mechanics. It suggests that all possible outcomes of a quantum measurement are realised in their own separate, parallel universes. In contrast, the 'Bubble Universe' theory originates from cosmology and eternal inflation, proposing physically separate universes existing in a larger cosmic space, each born from a distinct Big Bang-like event.
6. If other universes exist, could they have different laws of physics?
This is a key question, and the answer depends on the specific multiverse model. In some theories, like the String Theory Landscape, other universes could indeed have different fundamental constants and physical laws. For example, the strength of gravity or the charge of an electron might be different, making those universes drastically different from ours. In other models, like the Many-Worlds Interpretation, the fundamental laws of physics are believed to be the same across all branching universes.
7. Why is the multiverse concept currently considered a scientific hypothesis rather than a proven theory?
The multiverse is considered a hypothesis because it is not yet falsifiable—a key requirement for a scientific theory. Falsifiability means that there must be a way to test the idea and potentially prove it wrong. Since we currently lack the means to observe or interact with other universes, we cannot conduct experiments to confirm or deny their existence. While it is a logical extension of some existing theories, it remains in the realm of theoretical physics until testable predictions can be made and verified.
