By Aashritha Shankar
~ 11 minutes
While the concepts of space and time were fundamental to the Newtonian world, centuries of digging deeper into the mechanics of our universe have uncovered that it isn’t all as simple as it seems. From Einstein’s Special Relativity to theories of multi-dimensional time, the science behind space and time has evolved into a complex field.
Why Extra Temporal Dimensions?
The search for extra spatial dimensions raises questions of the potential for extra temporal dimensions. If space can have more dimensions, why can’t time? The motivations to explore the potential for extra temporal dimensions arise from a desire to better understand the nature of time and the symmetries between them.
Another reason to study these extra-temporal dimensions is the desire to unify seemingly disconnected parts of time. Many frameworks for extra temporal dimensions have revealed previously unnoticed symmetries and relationships between different temporal systems that would not be discovered while only working in one dimension.
The concept of “complex time” is used to fix some of the problems of quantum mechanics. This idea suggests that time should be represented as a complex value rather than a real number. It would allow more ways to represent wave-particle duality, entanglement, and other fundamental concepts of quantum physics.
2T-Physics
Proposed by physicist Itzhak Bars, 2T-Physics suggests that the one dimension of time we experience is really just a “shadow” of the real two dimensions of time. The core motivation of 2T-Physics is to reveal the deeper temporal connections that we don’t see in our one-dimensional perspective. In 2T-Physics, two seemingly disconnected temporal systems are actually connected and represent different views or ‘shadows’ of the same two-dimensional time.
2T-Physics unifies a wide range of physical systems using “gauge symmetry,” which is the property of a system where a set of transformations, called gauge transformations, can be used on a system without changing any of the physical properties of that system. Bars also illustrated that the Standard Model could be explained by 2T-Physics with four spatial dimensions. Not only can this model predict most of the Standard Model, but it also provides a solution to some quantum issues.
An interesting difference between the Standard Model and the predictions of 2T-Physics is the gravitational constant. While it is currently established that the coefficient in gravitational equations is a constant 6.67⋅10-11, the mathematics of 2T-Physics means that the gravitational constant has different values for different periods of our universe (inflation, grand unification, etc). This allows new possibilities for early expansion of our universe that General Relativity and the Standard Model do not. Through its new perspectives, 2T-Physics allows a more complete framework of gravity, especially at higher dimensions.
While 2T-Physics is well-established, it remains highly theoretical and has little to no practical impact. While there is no evidence directly supporting the theory, 2T-Physics predicts certain connections between different physical systems that could potentially be verified through complex experiments, though none have been conducted so far. Above all, 2T-Physics provides a new perspective on time and the nature of the laws of physics that has opened the eyes of many scientists and will likely inspire future discoveries.
3D Time
One of the most recent papers in the field, Kletetschka, proposes a mathematical framework of spacetime that includes temporal dimensions. Kletetschka provides a new perspective on combining gravity and quantum mechanics. Instead of having two hidden dimensions of time, Kletetschka theorizes that each of these dimensions is used to represent time at different scales: the quantum scale, the interaction scale, and the cosmological scale. He explains that the other two dimensions are not visible in our daily life because they occur at very small (quantum) levels or very large (cosmological) levels.
A massive difference between this theory and conventional physics is that while conventional physics considers space to be something vastly different from time, Kletetschka proposes that space is a byproduct of time in each of these dimensions, rather than an entirely separate entity. What we experience as mass or energy actually arises from the curvature of time in these three dimensions. As Kletetschka explored more into this, he discovered surprising consistency in the mathematics, leading to a deeper exploration into the concept.
The key to not creating causality issues and instability in the theory was the usage of regular geometry and spatial dimensions instead of exotic situations that are hard to prove or test. This theory aimed to address many of the long-standing issues in quantum mechanics, and its success thus far makes it a prominent theory in the field.
The theory is able to add extra temporal dimensions without causing causality issues, something very few theories of its type have been able to grapple with. This is due to its structure. The theory is designed so that the three axes share an ordered flow, preventing an event from happening before its cause. Furthermore, these three axes operate at very different scales, leaving very little overlap between them. The mathematics of the framework does not allow for the alteration of events in the past, something that many other theories allow.
The theory is able to offer physical significance and a connection to our world alongside mathematical consistency. Things such as finite quantum corrections, which other theories were not able to predict, were mechanized by this model without creating extra complexity.
This mathematical framework is able to predict several properties and new phenomena that can be experimentally tested, allowing pathways to prove or disprove it soon. Meanwhile, many scientists have spoken in support of the theory, considering it a promising candidate for a near “Theory of Everything” just a few months after its publication.
Conclusion
While the theoretical motivation for extra dimensions is compelling, the reality of their existence remains unconfirmed. Meanwhile, the scientific community works to experimentally prove or disprove their existence through observational evidence.
The Large Hadron Collider (LHC) at CERN is one of the major players on the experimental side. They engage in many experiments, a few of which I have highlighted below.
- Tests for Microscopic Black Holes: Many of the theories that propose extra dimensions lead to increased gravitational power within short distances. This manifests physically as microscopic black holes that would dissipate near instantaneously due to Hawking Radiation. However, the byproduct of this dissipation would be particles detected through the LHC.
- The Graviton Disappearance: Another common feature of extra-dimensional theories is the manifestation of gravity as a particle called a graviton. That particle would disappear into these extra dimensions, taking energy with it. This would result in an imbalance in the total energy of the system.
While experiments have managed to provide more limitations for potential values that would work in certain theories, they have yet to prove or disprove them.
Meanwhile, it is important to consider what extra dimensions would mean for us and the way we live. The concept of extra dimensions provides multiple philosophical considerations for us as humans. This concept completely changes our worldview and affects our perception of the universe. Dr. Michio Kaku explains this through the analogy of a fish in a pond, unaware of the world outside its simple reality. Our perception of reality is limited, not only by our understanding of physics, but also by the biology of our brains.
The work towards a “Theory of Everything” is not only a physical goal but a philosophical one as well. We strive to understand our universe and everything within it in the simplest way possible. It embodies human desire for ultimate knowledge and drives centuries of physical progress.
Overall, the concept of extra dimensions represents one of the most arduous and ambitious goals in human history. While they lack proof, these theories motivate people to search more into the nature of our universe and question the very fabric of our reality. The exploration into further discoveries about our universe truly shows who we are as humans and will continue to motivate centuries of physicists to question the very nature of everything.
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