Books and Articles by Daniel Robbins

The multiverse is a theory that suggests our universe is not the only one, and that many universes exist parallel to each other. These distinct universes within the multiverse theory are called parallel universes. A variety of different theories lend themselves to a multiverse viewpoint.Not all physicists really believe that these universes exist.

General relativity was Einstein’s theory of gravity, published in 1915, which extended special relativity to take into account non-inertial frames of reference — areas that are accelerating with respect to each other.General relativity takes the form of field equations, describing the curvature of space-time and the distribution of matter throughout space-time.

General relativity was Einstein’s theory of gravity, published in 1915, which extended special relativity to take into account non-inertial frames of reference — areas that are accelerating with respect to each other. General relativity takes the form of field equations, describing the curvature of space-time and the distribution of matter throughout space-time.

Many physicists feel that string theory will ultimately be successful at resolving the hierarchy problem of the Standard Model of particle physics. Although it is an astounding success, the Standard Model hasn’t answered every question that physics hands to it. One of the major questions that remains is the hierarchy problem, which seeks an explanation for the diverse values that the Standard Model lets physicists work with.

For most interpretations, superstring theory requires a large number of extra space dimensions to be mathematically consistent: M-theory requires ten space dimensions. With the introduction of branes as multidimensional objects in string theory, it becomes possible to construct and imagine wildly creative geometries for space that correspond to different possible particles and forces.

String theory seems to violate the rule of simplicity. In science, one goal is to propose the fewest “entities” or rules needed to explain how something works. In many ways, the history of science is seen as a progression of simplifying the complex array of natural laws into fewer and fewer fundamental laws. Take Occam’s razor, which is a principle developed in the 14th century by Franciscan friar and logician William of Occam.

In trying to understand the universe, two major problems remained: the flatness problem and the horizon problem. To solve these, the big bang theory is modified by the inflation theory, which states that the universe expanded rapidly shortly after it was created. Today, the principles at the heart of inflation theory have a profound impact on the way that string theory is viewed by many physicists.

Causal dynamical triangulations’ biggest flaw in comparison to string theory is that it doesn’t tell us anything about where matter comes from, whereas matter arises naturally in string theory from the interactions of fundamental strings. The causal dynamical triangulations (CDT) approach consists of taking tiny building blocks of space, called 4-simplices (sort of like multidimensional triangles), and using them to construct the space-time geometry.

Many of the prominent critics of string theory who are working on other approaches — Lee Smolin, John Moffat, Fotini Markopoulou, and others — call the Perimeter Institute for Theoretical Physics home, so it’s easy to believe that the Perimeter Institute seeks out anti-string theorists. In fact, their current director is Neil Turok, a cosmologist and co-creator of the ekpyrotic model, which is based on string theory principles.