ABSTRACT
Gravity, although the oldest force known to man, is the force we understand the least. The weakness of the gravitational force precludes the possibility of performing simple experiments that will teach us more about this omnipresent force. Apart from gravity there are three other fundamental forces in Nature: the electromagnetic force, the weak force and the strong force. Fundamental here means that all forces we encounter may be attributed to one of these four forces. For example, the force of tension, seen frequently in mechanics problems, is electromagnetic in origin. Three of the fundamental forces are described by quantum Yang-Mills theories and theoretical predictions have, with stunning accuracy, matched experimental observations. Gravity, the fourth fundamental force, has a well tested description: the Einstein-Hilbert theory. However, this is a “classical” theory, meaning that it does not offer an accurate microscopic description. Such a description would require a quantum theory of gravity - something researchers have been working towards for several decades (without success). A problem that looms large in this search is the very structure of gravity. In this self-contained article we will attempt to explain this problem.
