Martin Bojowald

 

On his book Once Before Time: A Whole Story of the Universe

Cover Interview of March 09, 2011

The wide angle

Ten years ago, I wanted to understand and test the mathematics behind some of the theories already proposed at that time, especially in Loop Quantum Gravity. In the process, over several years, it turned out that the simplest way to test the mathematics was to look at the cosmological outcomes of the equations.  Those cosmological solutions quickly and unintentionally showed the possibility of determining what happened before the big bang.

The book describes the results obtained in the meantime—and some of the personal experiences I had along the way.  I outline a view of the universe’s nature and of time according to General Relativity, Quantum Mechanics, and Loop Quantum Cosmology. 

For the reader to appreciate the endeavors of understanding the world on its largest and smallest scales, the book provides privileged insight into the concepts of relativity, space-time, quantum physics, black holes, and expanding universe.  I also write about how science affects other fields of cultural inquiry.

General Relativity governs the entire universe and the vast distributions of matter within it.  Quantum Physics is the realm of the very tiny individual particles and atoms.  A combination of these two theories, called Quantum Gravity, allows us to see space-time in a quantized fashion.

The quantum universe of space-time is no longer unstructured and continuous, but more like matter, which is composed of small, discrete atoms. During the big bang, the universe was tiny, collapsed to nearly a single point. In this point, the arrangement of its space-time atoms determined the universe’s fate. By understanding the laws governing these spatial atoms, it may be possible to decipher the universe’s prehistory—the universe before the big bang.

Although spatial atoms are so tiny that they cannot yet be seen, theoretical physics has provided a strong line of arguments for their existence. The evidence is purely mathematical, but its consequences can be grasped intuitively.

The densest moment of the big bang is described as being a “State of Hell,” where the universe is infinitely hot and devoid of space. This state persists timelessly, for in it there is no space-time or change.


rorotoko.com Illustration of a model universe, spiraling out of nothingness (the so-called “State of Hell” of Loop Quantum Gravity) and then rapidly expanding to the right. The figure overlays states of the early universe at all times, characterized by its extension (vertical axis) and expansion rate (horizontal axis). Brighter colors correspond to states occupied more often. (Martin Bojowald)

However, a single spatial atom’s disturbance of this situation implies that more and more spatial atoms will be generated and excited. As a result, space and time emerge, and the universe grows independently of matter.

Even after space had grown to the present cosmic scales, the atomic interplay may still have left a trace in the formation of structures we see today, such as the distribution of galaxies. In this indirect way, the notion of spatial atoms is empirically testable.

The book also outlines some of the predictions that could eventually be called upon to test Quantum Gravity.