hundred billion galaxies which are thought to comprise our observable universe
(Streeter 2016).
While the magnetic field of the Earth has fluctuated over the eons, temperatures
change with time and the light intensity undergoes seasonal and daily cycles, gravity
has constantly governed the evolution of life on Earth with an acceleration of
9.81 m s
À2 (¼1 g). All forms of life have been constantly exposed to gravity during
the entire evolution. It controls the vertical growth of trees (Fig. 1.1) and prevents us
from falling from the surface of the globe even “down under”. In fact, gravity affects
almost all biological, chemical and physical processes on the molecular, cellular and
organismic level on Earth and is utilized in many ways by organisms since the
beginning of the evolution of life more than 3.5 billion years ago.
Fig. 1.1 Trees grow
vertical parallel to the
gravity vector and away
from the center of gravity
(negative gravitropism) and
not perpendicular to a
sloping Earth surface
1.2 Gravity and the Evolution of Life on Earth
3
(Streeter 2016).
While the magnetic field of the Earth has fluctuated over the eons, temperatures
change with time and the light intensity undergoes seasonal and daily cycles, gravity
has constantly governed the evolution of life on Earth with an acceleration of
9.81 m s
À2 (¼1 g). All forms of life have been constantly exposed to gravity during
the entire evolution. It controls the vertical growth of trees (Fig. 1.1) and prevents us
from falling from the surface of the globe even “down under”. In fact, gravity affects
almost all biological, chemical and physical processes on the molecular, cellular and
organismic level on Earth and is utilized in many ways by organisms since the
beginning of the evolution of life more than 3.5 billion years ago.
Fig. 1.1 Trees grow
vertical parallel to the
gravity vector and away
from the center of gravity
(negative gravitropism) and
not perpendicular to a
sloping Earth surface
1.2 Gravity and the Evolution of Life on Earth
3