| Abstract
| - Abstract. The Brans-Dicke (BD) theory of gravity is taken as a possible theory of k-essence coupled to gravity. It is then realized that the BD scalar field does indeed play the role of a k-essence, but in a very unique way which distinguishes it from other k-essence fields studied in the literature. That is, first in the BD scalar field-dominated era when the contribution from this k-essence overwhelms those from other types of matter, BD theory predicts the emergence of a yet-unknown zero acceleration epoch, which is an intermediate stage acting as a ‘crossing bridge’ between the decelerating matter-dominated era and the accelerating phase. Upon realizing this, next, a closer study of the effects of this k-essence on the evolutionary behaviour of the matter-dominated and the accelerating eras has been performed. The result of the study indicates that the BD scalar field appears to interpolate smoothly between these two late-time stages by speeding up the expansion rate of the matter-dominated era somewhat, while slowing down that of the accelerating phase to some degree. Thus, with the newly found BD scalar field-dominated era in between these two, the late-time of the Universe evolution appears to be mixed sequence of the three stages.
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