Supercomputer Solves The Space-Time Dimensionality Riddle.
Spacetime, which consists of three dimensions of space and one time dimension, is such a large, abstract concept that scientists have a very difficult time understanding and defining it.
We know we live in a 3-dimensional world, but the Universe was born with 10 dimensions. So, where are those hidden dimensions? This has been a big mystery to physicists.
But now a supercomputer simulating the Big Bang has finally solved what is known as the string theory. According to Big Bang cosmology, the universe originated in an explosion from an invisibly tiny point. This theory is strongly supported by observation of the cosmic microwave background and the relative abundance of elements.
However, a situation in which the whole universe is a tiny point exceeds the reach of Einstein’s general theory of relativity, and for that reason it has not been possible to clarify how the universe actually originated.
In superstring theory, which is considered to be the “theory of everything”, all the elementary particles are represented as various oscillation modes of very tiny strings. Among those oscillation modes, there is one that corresponds to a particle that mediates gravity, and thus the general theory of relativity can be naturally extended to the scale of elementary particles.
Therefore, it is expected that superstring theory allows the investigation of the birth of the universe. However, actual calculation has been intractable because the interaction between strings is strong, so all investigation thus far has been restricted to discussing various models or scenarios.
Invisible dimensions cannot be seen with the naked eye
Superstring theory predicts a space with 9 dimensions3, which poses the big puzzle of how this can be consistent with the 3-dimensional space that we live in. A group of 3 researchers, Jun Nishimura (associate professor at KEK), Asato Tsuchiya (associate professor at Shizuoka University) and Sang-Woo Kim (project researcher at Osaka University) has succeeded in simulating the birth of the universe, using a supercomputer for calculations based on superstring theory.
This showed that the universe had 9 spatial dimensions at the beginning, but only 3 of these underwent expansion at some point in time. In this study, the team established a method for calculating large matrices (in the IKKT matrix model4), which represent the interactions of strings, and calculated how the 9-dimensional space changes with time. In the figure, the spatial extents in 9 directions are plotted against time.
The first time, that the 3-dimensional space that we are living in indeed emerges from the 9-dimensional space that superstring theory predicts. This calculation was carried out on the supercomputer Hitachi SR16000 (theoretical performance: 90.3 TFLOPS) at the Yukawa Institute for Theoretical Physics of Kyoto University.
It is almost 40 years since superstring theory was proposed as the theory of everything, extending the general theory of relativity to the scale of elementary particles. However, its validity and its usefulness remained unclear due to the difficulty of performing actual calculations. The newly obtained solution to the space-time dimensionality puzzle strongly supports the validity of the theory.Source: MessageToEagle.com
Steven Ludmon for 'Astro Space News'
