  The rising complexity of our terrestrial surrounding is an empirical fact.
Details of this process evaded description in terms of physics for long time
attracting attention and creating myriad of ideas including non-scientific
ones. In this essay we explain the phenomenon of the growth of complexity by
combining our up to date understanding of cosmology, non-equilibrium physics
and thermodynamics. We argue that the observed increase of complexity is causal
in nature, stands in agreement with the second law of thermodynamics and has
it's origin in the cosmological expansion. Moreover, we highlight the
connection between the leader of complexity growth in localized areas of space
with free energy rate density, starting from the largest scales towards the
smaller ones. Finally, in the light of recent advances in non-equilibrium
statistical mechanics, our belief in the causal structure of modern scientific
theories is transferred to biological systems. On relevant scales, adaptation
and complexity growth follows a similar pattern, in which free energy rate
density is provided by an external electromagnetic radiation. The presented,
holistic approach, arms us with predicting power about variety of attributes of
complex systems and leads to a chain of successful explanations on all scales
of the Universe.
