Main Article Content
from manifold considerations — nuclear, astrophysical, chemical and geophysical.
Basically, there are two schools of thought: monistic, which
postulates that the sun and the planets formed from some primordial system
of gases; and dualistic, which holds that the planets and meteorites had
genesis in the sun's collision wtili another star. The extreme improbability
of collision almost discards this hypothesis.
The present day accepted theories are, hence, the monistic ones, and
the one particularly favored is the Dust — cloud hypothesis — that the sun
condensed into a star due to the gravitational collapse of a massive interstellar
gas-cloud, and subsequently gave birth to planets as further evolution
of the cloud progressed. Studies of extinct radioactivities, within the
framework of the above hypothesis, give clue to the early history of the
solar system and in particular indicate that the time interval between the
start of condensation and the formation of the meteorite parent-bodies is
less six million years (Cameron). In this context the origin of stars from
" globules " or proto-stars has been briefly discussed.
A somewhat " exotic " theory of the formation of planets from the
sun which hinged on the concept of secular decrease of the ' constant ' of
gravitation with the age of the universe (Dirac's hypothesis) has been discussed.
The earth (with expansion of its volume) and other celestial
bodies might provide empirical confirmation of the concept of diminishing
gravitation — an important problem of general relativity. This new idea
of physics might revolutionise fundamental concepts in geology and geophysics.
No Permission Required
Istituto Nazionale di Geofisica e Vulcanologia applies the Creative Commons Attribution License (CCAL) to all works we publish.
Under the CCAL, authors retain ownership of the copyright for their article, but authors allow anyone to download, reuse, reprint, modify, distribute, so long as the original authors and source are cited. No permission is required from the authors or the publishers.