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The definition of life has long been a challenge for scientists and philosophers. [2] [3] [4] This is partially because life is a process, not a substance. [5] [6] [7] This is complicated by a lack of knowledge of the characteristics of living entities, if any, that may have developed outside Earth.
The earliest evidence for life on Earth includes: 3.8 billion-year-old biogenic hematite in a banded iron formation of the Nuvvuagittuq Greenstone Belt in Canada; [30] graphite in 3.7 billion-year-old metasedimentary rocks in western Greenland; [31] and microbial mat fossils in 3.48 billion-year-old sandstone in Western Australia.
The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest emergence of life to the present day. Earth formed about 4.5 billion years ago (abbreviated as Ga, for gigaannum) and evidence suggests that life emerged prior to 3.7 Ga. [1] [2] [3] The similarities among all known present-day species indicate that they have diverged through the ...
Science is a systematic discipline that builds and organises knowledge in the form of testable hypotheses and predictions about the universe. [1] [2] Modern science is typically divided into two or three major branches: [3] the natural sciences (e.g., physics, chemistry, and biology), which study the physical world; and the social sciences (e.g., economics, psychology, and sociology), which ...
A canon event is a transformative moment that redefines you as a person. It can range from heartbreak to triumph—the loss of a loved one, a promise to get sober, or landing a dream job.Reddit ...
This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms.It is intended as introductory material for novices; for more specific and technical definitions from sub-disciplines and related fields, see Glossary of cell biology, Glossary of genetics, Glossary of evolutionary biology, Glossary of ecology ...
A natural phenomenon is an observable event which is not man-made. Examples include: sunrise , weather , fog , thunder , tornadoes ; biological processes , decomposition , germination ; physical processes , wave propagation , erosion ; tidal flow , and natural disasters such as electromagnetic pulses , volcanic eruptions , hurricanes and ...
In some specific fields of science, the results of observation differ depending on factors that are not important in everyday observation. These are usually illustrated with apparent "paradoxes" in which an event appears different when observed from two different points of view, seeming to violate "common sense".