Such observations on nebulæ caused Kant and Laplace to suggest a theory--now known as thenebular theory--as to the formation of worlds.
Among the ascertained analogies between the stellar and nebular systems is that of variability of light.
An approximate coincidence between the chief nebular line and a "fluting" of magnesium having been alleged by Lockyer in support of his meteoritic hypothesis of nebular constitution, it became of interest to ascertain its reality.
The structural unity of the stellar and nebular orders in this extensive region of the sky has also, by direct photographic means, been unmistakably affirmed.
All of these gave the green ray fundamental to the nebular spectrum, and emanating from an unknown form of matter named by Sir William Huggins "nebulum.
In each a green ray, approximating in position to the fundamental nebular line, crossed an otherwise unbroken spectrum.
But under Herschel's treatment the nebular origin of stars first acquired the consistency of a formal theory.
Indeed the whole nebular theory is now being called in question.
If the "nebular theory" of the universe be true, this is unquestionably the exact condition of things in the Milky-way.
At first there was no suggestion of a nebular constitution, but within a month or two characteristic nebular lines began to appear, and in less than six months the whole spectrum had been transformed to the nebular type.
On some of the nebular lines, which are either straight throughout, or if they change direction do so at an angle, little stars are strung like beads.
So Hegel fell far behind Kant in this respect for the latter had already by his nebular hypothesis proclaimed the origin and, by his discovery of the stoppage of the rotation of the earth through the tides, the destruction of the solar system.
The fact that matter passed through an endless series of other forms before arriving at the nebular state is not excluded from this conception but is on the other hand rather included in it.
Fortunately we are informed that the nebular hypothesis of Kant "is far from showing a fully distinct condition of the world-medium or of explaining how matter arrived at a similar state.
What is there to hinder Herr Duehring himself from discovering the mechanical system of the original nebular state?
It is to be remarked by the way that although the nebular condition of Kant is supposed to be the original vapor-form of matter, this is to be understood merely relatively.
The next step was to revive Laplace's nebular hypothesis, and to connect it through Lyell's uniformitarian geology with Lamarck's developmental biology, thereby extending the same evolutionary process through the whole history of the universe.
Kant offered a brilliant solution of the problem in his Natural History of the Heavens (1755), a work embodying the celebrated nebular hypothesis rediscovered forty years later by Laplace.
The nebular hypothesis affords a good illustration of the distinction which I am endeavoring to show you, whether it is well established or not, or is ever likely to be.
This theory is what is called the nebular hypothesis.
Concerning the nebular hypothesis, and what astronomers now consider, see post.
This startling achievement by Lord Rosse's telescope was the signal for the abandonment of the nebular hypothesis by many of its former advocates.
On the other hand, if the nebular hypothesis was not true, the occurrence of these gaps was not to be expected.
Indeed, it is more true of the theory of gravitation, and of the nebular hypothesis, than of the hypothesis in question.
The nebular hypothesis--a natural consequence of the theory of gravitation and of the subsequent progress of physical and astronomical discovery--has been denounced as atheistical even down to our own day.
On the other hand, the theory of gravitation and its extension in the nebular hypothesis assume a universal and ultimate physical cause, from which the effects in Nature must necessarily have resulted.
We are disposed to rank the derivative hypothesis in its fullness with the nebular hypothesis, and to regard both as allowable, as not unlikely to prove tenable in spite of some strong objections, but as not therefore demonstrably true.
Yet the nebular hypothesis finds general scientific acceptance, and is adopted as the basis of an extended and recondite illustration in Mr. Agassiz's great work.
Perhaps scarcely any philosophical objection can be urged against the former to which the nebular hypothesis is not equally exposed.
Whatever purely literary talent existed was as yet in the nebular condition, a diffused luminous spot here and there, waiting to form centres of condensation.
The scheme here given is a combination of the conclusions of Dana and Guyot, and assumes the substantial truth of the nebular hypothesis.
With this to start with, he utilised the "Nebular Hypothesis" of Laplace, which showed how the planetary system may have arisen by the diffused matter becoming aggregated through the force of attraction into different centres.
Having traced the developmental process from the nebular to the dark star, it sees no cause to abandon this dark star to its fate by assuming, as the original speculation assumed, that this is a culminating and final stage of cosmic existence.
This contention had the theoretical support of the nebular hypothesis, then gaining ground, which supposed the earth to be a cooling globe.
Croll imagines of the dark bodies which his "pre-nebular theory" postulates.
His theory, known as the "meteoric hypothesis," probably bears the same relation to the speculative thought of our time that the nebular hypothesis of Laplace bore to that of the eighteenth century.
The nebular hypothesis thus given detailed completion by Laplace is a worthy complement of the grand cosmologic scheme of Herschel.
Gravity eventually brings the nebular particles into closer aggregations, and increased collisions finally vaporize the entire mass, forming planetary nebulae and gaseous stars.
An analysis of thenebular hypothesis deals with facts of so august a nature, on so nearly an unimaginable plane, that intimacy seems out of place, impudent, like levity in cathedrals.
If the subject is itself interesting or remarkable, the facts may speak for themselves, as in an account of the nebular hypothesis; if the subject is merely common, as for example the force pump, the primary aim should be clearness.
Such are a few of the many difficulties in the way of accepting the nebular hypothesis, as at present explained, as being the true mode of development of the solar system.
He gave us the fundamental idea of what is called the nebular hypothesis.
There are some difficulties in the way of the acceptance of the nebular hypothesis that compel many of the most thorough scientists of the day to withhold their assent to its entirety.
The five great classes of facts that sustain the nebular hypothesis seem set before us to show the regular order of working.
Whether, however, the nebular hypothesis lays down the road travelled to this transfiguration, we are not sure.
When men attempt to roll the hypothesis of evolution along the road of the nebular hypothesis of worlds, and even beyond to the production of vegetable and animal life, mind and affection, the gaps in the road become evident, and disastrous.
The nebular hypothesis has surveyed, worked, and perfected many long reaches of this road, but the rivers are not bridged, the chasms not filled, nor the mountains tunnelled.
Whatever truth there may be in the theory will survive, and be incorporated into the final solution of the problem; which solution will be a much grander generalization of the human mind than the nebular hypothesis.
Tyndall's expressions on the Nebular Theory, 15; reference to Nebular Theory, 24.
A profound believer in evolution, he exempts man from the inexorable logic of the principle with about as much reason as if, confessing his belief in the nebular hypothesis, he should insist that the Earth was an exception.
He was graduated from Harvard in 1876, and prepared for his graduating thesis an essay on the Nebular Hypothesis.
With results as precious as when I examine the nebular theory and explain it to myself.
It was about 1847 that Mr. Youmans was deeply interested in the work of geologists, as well as in the Nebular Theory, to which recent discoveries were adding fresh confirmation.
We do not call the evolution of organic life on the earth subject or subordinate to the motion of the nebular mists, or passive with respect to them.
The New Astronomy, like the old, begins with a nebular hypothesis.
The orbit was thus cleared of the matter, which was at first merely nebular, and afterward both nebular and fragmentary.
By the continual revolution of this mass, under the influence of the centripetal and centrifugal forces, a circular nebular ring separated (like the present ring around Saturn) from the rotating ball.
Whewell[29] has pointed out, that the nebular hypothesis is null without a creative act to produce the inequality of distribution of cosmic matter in space.
We are disposed to rank the derivative hypothesis in its fulness with the nebular hypothesis, and to regard both as allowable, as not unlikely to prove tenable in spite of some strong objections, but as not therefore demonstrably true.
And where this nebular region, marked by the zodiacal light, terminates, the world of life begins, namely at the Earth.
It may be that the star has not yet assumed a spherical form, but is an oblong nebular mass with one part (perhaps from being thinner in texture) cooled down and become opaque.
This is the Nebular Hypothesis, suggested by the elder Herschel, and adopted by the great mathematician Laplace.
To conceive planetary systems as formed by the gradual contraction of a nebular mass, and by the solidification of some of its parts, is a favorite notion of several speculators.
There is one additional remark, which we may make, as to the resemblance of cometary[9] and nebular matter.
To this, the reply which we must make is, that the size of the nebular space is such, that though its rarity is extreme, its whole mass is considerable.
We must needs suppose a vast number of stages between a nebular chaos and the lowest forms of conscious life.
