Life is a characteristic of
organisms that exhibit certain
biological processes such as
chemical reactions or other events that results in a transformation. Living organisms are capable of growth and reproduction, some can
communicate and many can
adapt to their environment through changes originating internally.
[1] A
physical characteristic of life is that it feeds on
negative entropy.
[2][3] In more detail, according to physicists such as
John Bernal,
Erwin Schrödinger,
Eugene Wigner, and
John Avery, life is a member of the class of phenomena which are open or continuous systems able to decrease their internal
entropy at the expense of substances or
free energy taken in from the environment and subsequently rejected in a degraded form (see:
entropy and life).
[4][5]
An entity with the above properties is considered to be a
living organism, hence, a 'life form'. However, not every definition of life considers all of these properties to be essential. For example, the capacity for
evolution is sometimes taken as the only essential property of life; this definition notably includes
viruses, which do not qualify under narrower definitions as they are
acellular and do not metabolize.
A diverse array of living organisms can be found in the
biosphere on Earth. Properties common to these organisms
plants,
animals,
fungi,
protists,
archaea and
bacteriaare a
carbon- and
water-based
cellular form with complex
organization and heritable
genetic information. They undergo
metabolism, possess a capacity to grow, respond to
stimuli,
reproduce and, through
natural selection, adapt to their environment in successive generations.
So far, there is no evidence of extraterrestrial life.
I have to disagree with that statement. I think evidence of extraterrestial life has been found HERE!!!!!! Since we are all claiming to have no life. We must all be aliens.