Supergravity and the Nature of the Universe: Strings, Membranes, and Dimensions

Matter and all fundamental particles of nature are made up of invisible strings. Supergravity is a field theory that includes and interacts through gauge transformations across a large number of superfields. Currently, it is the most promising candidate for quantum gravity, combining the principles of supersymmetry and general relativity. The eleventh dimension is the maximum dimension in which we can realize supersymmetry within the framework of ordinary supergravity theory.

The theory itself explores membrane models and allows for the existence of parallel universes. Supergravity theory incorporates additional dimensions in its theoretical framework. These extra dimensions are spaces in the universe that we cannot perceive with our senses. Supergravity describes a universe made up of eleven space-time dimensions, including models characterized by different numbers of dimensions. It is a relatively elegant theory that has long existed in the shadow of string theory as a unifying, universal theory.

Supergravity posits that the universe consists of eleven dimensions. The eleventh dimension is thought to contain various membranes, which model parallel universes. Supergravity theories in different dimensions now play a significant role as low-energy effective field theories of superstrings and membrane models. M-theory and eleven-dimensional supergravity also predict the existence of objects called "supermembranes."

Multiverses and Membranes
An alternative cosmological theory is linked to the idea that we live on one of these membranes. The requirements of supersymmetric membranes suggest that the eleven-dimensional, maximally symmetric supergravity theory is favored over its lower-dimensional space-time counterparts. Supermembranes are hypothetical objects that exist and build the eleven-dimensional supergravity theory, constructing interactions that propagate in the supergravity background. The theory describes consistent interactions of the membrane and multiplets of matter, representing manifolds of superfields.

It has been shown that the low-energy vibrations of the supermembrane correspond to all superfields in eleven-dimensional supergravity. Since the vibrations of a supermembrane with infinite energy can correspond to any particle in the universe, it is possible to interpret that the supermembrane constructs the universe—that is, everything that exists is a fundamental supermembrane. We exist within this supermembrane, encompassing eleven-dimensional space-time. Every state of matter in the universe corresponds to a supermembrane, and every event in this universe corresponds to the volume of the supermembrane.

The significance of the concept of parallel universes can be understood through analyzing the consequences of supergravity theory. This theory can explain the theory of everything, the weak nature of gravity, the nature of time, singularity, and the Big Bang. All these theories have been among the greatest unsolved mysteries of physics, which the concept of parallel universes can potentially explain. The concept of parallel universes clarifies supergravity, string theory, membrane theory, and the eleven dimensions that are part of our physical reality. All these theories lead to the theory of everything, which provides the reason why we exist in this unique universe.

Strings, Membranes and Dimensions
String theory suggests that matter and all fundamental particles of nature are composed of invisible strings, which vibrate like strings, and this phenomenon exists in ten dimensions. Of these ten dimensions, time is the fourth, while the remaining six are spatial dimensions that humans cannot perceive with their senses. Membrane theory extends this concept and states that our physical reality consists of eleven dimensions, and the eleventh dimension is supergravity.

The fundamental superstrings are intertwined within the membrane, and these superstrings are distributed across the eleven dimensions. Therefore, membrane theory, or M-theory, states that our universe is like a membrane. These membranes run parallel to one another and create a series of parallel universes. This theory has several important implications, as it explains many of nature's mysteries. One of the primary examples of such mysteries is the weak nature of gravity. One implication of M-theory suggests that gravity may leak from a parallel membrane into our universe or membrane, indicating that gravity might not be an inherent characteristic of our universe.

Parallel universes also challenge the general notion that time began with the Big Bang. This is the most fundamental dimension aside from the spatial dimensions. Thanks to supergravity, modern theory includes gravitino particles as the superpartners of the gravitational field. M-theory predicts an infinite number of particles with different masses and can also explain supergravity through the eleventh dimension using massless particles. Membranes have proven to be self-consistent in eleven dimensions and interact seamlessly. There are five ways to reduce the eleven-dimensional M-theory to ten dimensions, which yield five string theories. M-theory beautifully unifies ten-dimensional and eleven-dimensional physics into a single theory, whose low-energy limit is supergravity.