星云假说

[ noun ]
(cosmology) the theory that the solar system evolved from a hot gaseous nebula
<noun.cognition>

Hypothesis \Hy*poth"e*sis\, n.; pl. {Hypotheses}. [NL., fr. Gr.
? foundation, supposition, fr. ? to place under, ? under + ?
to put. See {Hypo-}, {Thesis}.]
1. A supposition; a proposition or principle which is
supposed or taken for granted, in order to draw a
conclusion or inference for proof of the point in
question; something not proved, but assumed for the
purpose of argument, or to account for a fact or an
occurrence; as, the hypothesis that head winds detain an
overdue steamer.

An hypothesis being a mere supposition, there are no
other limits to hypotheses than those of the human
imagination. --J. S. Mill.

2. (Natural Science) A tentative theory or supposition
provisionally adopted to explain certain facts, and to
guide in the investigation of others; hence, frequently
called a working hypothesis.

Syn: Supposition; assumption. See {Theory}.

{Nebular hypothesis}. See under {Nebular}.


Nebular \Neb"u*lar\, a.
Of or pertaining to nebul[ae]; of the nature of, or
resembling, a nebula.

{Nebular hypothesis}, an hypothesis to explain the process of
formation of the stars and planets, presented in various
forms by Kant, Herschel, Laplace, and others. As formed by
Laplace, it supposed the matter of the solar system to
have existed originally in the form of a vast, diffused,
revolving nebula, which, gradually cooling and
contracting, threw off, in obedience to mechanical and
physical laws, succesive rings of matter, from which
subsequently, by the same laws, were produced the several
planets, satellites, and other bodies of the system. The
phrase may indicate any hypothesis according to which the
stars or the bodies of the solar system have been evolved
from a widely diffused nebulous form of matter.