nebu

NEBULÆ—APPARENT AND REAL

THE BEGINNING OF THE NEBULA

The Earth's Beginning by Robert S. Ball is part of the HackerNoon Books Series. You can jump to any chapter in this book here . OBJECTIONS TO THE NEBULAR THEORY CHAPTER XVII. OBJECTIONS TO THE NEBULAR THEORY There are Difficulties in the Nebular Theory—The General Conformity of the Movements—Details of the Uranian Movements—The Anomaly in the Satellite of Neptune—Where the Difficulty Lies—The Fundamental Principle which Dynamics Offers for our Guidance—The Immense Contrast between the Nebula in its Original Form and its Final Form—Energy that could be Obtained by a rearrangement of our System—Probable Nature of the Present Change in the Plane of the Orbits of the Satellites of Uranus—The Similar Explanation in the Case of Neptune. No one will deny that there are points in connection with the nebular theory which present difficulties which to some seem important. We shall endeavour to estimate the significance of these difficulties in this chapter. They are certain anomalous phenomena presented by the planets Uranus and Neptune. The satellites which attend upon the planets exhibit a general conformity with those movements of the planets themselves on which we have dwelt in Chapters , , The planes in which the orbits of the satellites are contained are usually not much inclined to the plane of the ecliptic, and the directions in which the satellites revolve also agree with the general direction of the planetary movement. We find these conditions in the one satellite of the earth, in the two satellites of Mars, in the five satellites of Jupiter, in the eight or nine satellites of Saturn; but, when we come to Uranus and Neptune, the two outermost planets, we observe a striking but most instructive violation of the laws which we have found so consistently prevailing in the other parts of the solar system. XIV. XV. XVI. Let me first mention the special circumstances of Uranus. It is now known that this planet has four satellites. Of these, Titania and Oberon were both discovered by Sir William Herschel on January 11th, 1787. The two remaining satellites, named Ariel and Umbriel, were not discovered for more than half a century later by Mr. Lassell, on October 24th, 1851. It is, however, just possible that they were previously seen by Sir William Herschel. The innermost of the four satellites, Ariel, accomplishes a revolution in a day and a half, Umbriel goes round in four days and three hours, Titania in eight days and seventeen hours, and Oberon in thirteen days and eleven hours. We have already mentioned how the investigations of Newcomb show that these four satellites of Uranus revolve in the same direction and in the same plane; but this plane, instead of lying in or near the ecliptic, is very nearly perpendicular thereto, the actual angle being eighty-three degrees. This is one of the features in which the satellites of Uranus are in startling disobedience to the laws which have been so rigidly observed in most other parts of the system. But there is also a second anomaly. The direction in which the satellites move, when projected on the plane of the ecliptic, is found to be opposite to the universal direction in which all the other movements in the solar system are performed. Of course the fact that the plane of the orbits of the satellites lies so nearly at right angles to the plane of the ecliptic detracts somewhat from the significance of this circumstance. If the two planes were absolutely at right angles, there would be, of course, no projection at all, and, in the actual circumstances, the moment of momentum, when projected, loses nineteen-twentieths of its amount. It follows that in the actual position of the plane the abnormal direction in which the satellites are moving is not very material. It must be admitted that, in the position of the plane of their orbits and the direction of their movements, the satellites of Uranus are in contrast to what a hasty consideration of the nebular theory might have led us to expect. If the orbits of those satellites had all lain close to the plane of the ecliptic, and if the direction in which the satellites revolved had also conspired with that of the revolution of Uranus round the sun, and with all the other hundreds of movements which are in the same direction, there can be no doubt that we should in this place have been appealing to the satellites of Uranus as confirmatory evidence of the truth of the nebular theory. The fact that they move in a manner so totally at variance with what might have been expected cannot therefore be overlooked. Neptune, the outermost planet of our system, presents us also with difficulties of an analogous character. So far as the orbit of Neptune itself is concerned, it agrees entirely with the general planetary convention; the inclination of that orbit to the plane of the ecliptic is no more than six degrees, and the direction in which the outermost planet revolves round the frontier of our system is not different from the directions in which all the other planets revolve. We know nothing about the axis of rotation of Neptune except that it may be reasonably presumed to be in the same plane as the movement of its satellite. On October 10th, 1846, Lassell, with the help of his great telescope, suspected the existence of a satellite to Neptune, and he announced it definitely on July 7th, 1847. We are indebted to Newcomb for a careful investigation of the orbit of this satellite. It moves in a track which is practically circular, and it requires about five days and twenty-one hours to accomplish each revolution. Its inclination to the ecliptic is not so anomalous as in the case of Uranus, the inclination being in this case not more than thirty-five degrees. This is not much greater than the inclinations of the orbits of some of the asteroids, and it might have passed without much comment had it not been for the circumstance that the direction of motion of the satellite in this track is antagonistic to all the other movements in the solar system. This is indeed a more startling fact in some respects than the movements of the satellites of Uranus, for, as we pointed out, the plane of the orbits of the satellites of Uranus is so nearly perpendicular to the plane of the ecliptic that the direction of the movement could not be held to be of much significance. The satellite of Neptune, having an orbital inclination barely more than a third of a right angle, exhibits a retrograde movement which is in some respects the most anomalous feature in the solar system. These circumstances connected with the satellites of Uranus and Neptune have been sometimes brought forward as arguments against the nebular theory. What Laplace would have said to them we can only conjecture, for, at the time he brought out his theory, Neptune was entirely unknown, and none of the satellites of Uranus had been observed. But it has sometimes been urged that the movements of these two systems are inconsistent with the principles of the nebular theory, and that, therefore, the nebular theory must be abandoned. I have no desire to minimise the difficulties, but I think the considerations to which I now invite attention may help to lessen them even if they do not altogether remove them. I trust, at least, we may be able to show that even those anomalous movements are not incompatible with the acceptance of the account of the origin of our solar system given by the nebular theory. The primæval nebula may be regarded as chaotic in its earliest stages; perhaps it was like the nebulous wisps in Fig. . It was chaotic in the arrangement of the material of which it is formed, and in the movements of that material. Before a disorganised nebula can become evolved into a nebula with any definite form like that in Fig. , or into anything resembling a solar system, an immense period of time must elapse, and during that time the operation of the laws of dynamics gradually impresses certain well-marked features on the nebula, and disposes it to assume an orderly form. We have explained that no matter how the nebula originated, or no matter what may have been the irregularities in its extent or distribution, and no matter how diverse may have been the agitations of its various parts, the principles of dynamics assure us that each such nebula must, for all time, stand in some special relation to a certain particular plane. The moment of momentum which the nebula has with respect to this plane, exceeds the moment of momentum that it has with respect to any other plane. We have pointed out how, notwithstanding the vicissitudes and transformations to which, in the course of illimitable ages, the nebula must submit, its moment of momentum relatively to this plane will remain absolutely unaltered. We have shown how the energy of the nebula becomes gradually exhausted. The collisions between various particles, the frictions that will necessarily arise, and the actions which we may sufficiently describe by saying that they are of a tidal character, will all result in the transformation of energy into heat. This heat is radiated away and lost, and there is a corresponding decline in the energy of the system. To preserve its moment of momentum unaltered in the course of ages, notwithstanding the continuous reduction of energy, the materials of the nebula will ever find themselves more and more approximating to the plane, and will ever find themselves more and more compelled to revolve in the same direction. If the original size of the nebula be compared with the area of the Atlantic Ocean, the condensed form which the nebula may ultimately assume may be no larger than a coral island. If the nett moment of momentum, diffused over the space as large as the ocean, has still to be preserved in the space as large as the island, we need not be surprised that the spin of the system in its condensed form is its dominating characteristic. 51 52 In the evolution of our solar system from the primæval nebula, this operation of reducing the movements to the same plane and of requiring that all the movements shall take place in the same direction, having had play for unmeasured ages, has in the main accomplished its end. All the important bodies of the system do go round in the same direction; that much, at least, has been attained. All of them also go round in planes which are nearly coincident, but, as we have already noted, they are not yet absolutely coincident. The greatest planets have, however, very nearly become reconciled, so far as the planes of their orbits are concerned, to the condition which dynamics imposes. The same is true of the rotation of the sun on its axis. That axis is inclined at an angle of eighty-three degrees to the plane of the ecliptic, so that the sun’s equator would have to be shifted only through an angle no greater than seven degrees, if it were to be placed in the plane in which it should be situated, if the condition of the smallest quantity of energy for a given amount of moment of momentum was to be realised. We find a greater discrepancy in the plane of the earth’s equator. This is inclined by about twenty-three degrees to the plane of the ecliptic. Here there is some energy which might yet be expended without a diminution of the amount of moment of momentum in the system; for if the earth’s axis were to be made perpendicular to the plane of the ecliptic, then the velocity of rotation of the earth about its axis might undergo a corresponding abatement, and yet keep up the requisite moment of momentum. We thus see that even with the older planets the conditions which would be enforced, if the moment of momentum was to be sustained with the least quantity of energy, are not absolutely complied with; which simply means that there has not yet been time enough for our system to arrive at the perfect state, to which it must be approximating. If we have found that in the rotations of the earth and of the sun, and in the revolutions of the planets round the sun, the conditions ultimately aimed at have not yet been reached, why should we feel surprised that in the outer planets of our system, Uranus and Neptune, the conditions which evolution tends to produce have not yet been fully attained? That the operation of the conservation of moment of momentum is in progress in the internal economy of the Uranian system, we have already had occasion to explain in Chapter XI. The fact which Newcomb demonstrated, that the four satellites revolve in the same plane, can only be accounted for by the supposition that in that system the conservation of moment of momentum, with declining energy, has gradually imposed this condition on the system belonging to Uranus. With reference to the position of the plane of the satellites, in the case of Uranus and Neptune, we would say, that though at present their arrangement appears anomalous, it will probably not always remain so. The fact that the satellites of Uranus are in a plane nearly perpendicular to the plane of the ecliptic really implies that there is a certain amount of energy still disposable in our system, if by readjustment of the plane of the Uranian satellites the necessary moment of momentum in the system is still preserved. Fig. 52.—Two-branched Spiral (n.g.c. 7479; in Pegasus). (Lick Observatory.) The laws of dynamics tell us that the orbits of planets must be gradually, if with excessive slowness, tending still further to the same plane. In this process energy can be expended by the system, while the moment of momentum is unabated. We can at least suggest what seems to be at this moment in progress in the system belonging to Uranus. It will readily be admitted that there may be a difficulty in seeing how the movement of a planet, which is going in the wrong direction, could be stopped and turned into the right direction. But we need not suppose that so violent a change as this would imply is to be expected in our system. We are quite accustomed to find the planes of the orbits of all planets in gradual movement. The plane containing the orbits of the four satellites of Uranus is at this moment probably moving gradually upwards. It will in due course become actually at right 346angles to the ecliptic, and we may then reasonably assume that it will advance further in the same direction. At the moment the right angle is passed, this continuous movement will have the effect of changing the directions of the satellites’ movement from retrograde to direct. The present anomaly will then tend to become evanescent, for, as the exhaustion of the energy continues, the planes of the satellites of Uranus will gradually come into conformity with the plane of the ecliptic. We make no doubt that there may be a similar explanation of the movements of the satellite of Neptune. The inclination of the plane of the orbit of the satellite to the ecliptic is probably now increasing. It will ultimately come to be at right angles thereto, and then the next advance of the plane will convert, by a continuous action, the retrograde motion of the satellite, at present so disconcerting, into a direct motion. The change of the plane will still continue until it, too, may ultimately coalesce with the ecliptic. The fact appears to be, that though an enormous quantity of energy must have been lost by radiation from our system during the illimitable ages through which the evolution has been running its course, the disposable energy is not yet quite exhausted. There are certain adjustments in our system which may still be made and which will allow of yet further radiation of energy, while still preserving sufficient to keep up the necessary moment of momentum. It seems obvious that the system is tending towards a condition in which the planes of all the orbits shall be coincident, and in which all the directions shall be absolutely unanimous. If we were at once to alter the system by moving all the orbits into the plane of the ecliptic, but making no change in the dimensions of those orbits, or the velocities concerned; if we were also to adjust the rotations of the earth, as well as of the other planets, so that all the axes of rotation should be perpendicular to the plane of the ecliptic; if we were to turn the plane of the satellites of Uranus through that angle of 97°, which would suffice at the same time to bring it into coincidence with the ecliptic, and lay the movements of the satellites in the right direction; if we were also to turn the orbit of the satellite of Neptune through 145°, thus bringing that orbit to coincide with the plane of the ecliptic, in such a manner that the direction of the movement of the satellite of Neptune conspired with all the other movements of the system, then this rearrangement of the system would increase the moment of momentum, while the quantity of energy was not altered. But this is the same thing as saying that some energy yet remains to be disposed of, while the system still preserves the requisite moment of momentum. The conclusion we come to may be thus expressed: the movements of the satellites of Uranus and Neptune do not disprove the nebular hypothesis. They rather illustrate the fact that the great evolution which has wrought the solar system into form has not yet finished its work; it is still in progress. The work is very nearly done, and when that work shall have been completed, the satellites of Uranus and Neptune will no longer be dissociated from the general concord. About HackerNoon Book Series: We bring you the most important technical, scientific, and insightful public domain books. This book is part of the public domain. Robert S. Ball (2019). The Earth's Beginning. Urbana, Illinois: Project Gutenberg. Retrieved October 2022 https://www.gutenberg.org/cache/epub/59080/pg59080-images.html This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.org , located at https://www.gutenberg.org/policy/license.html .

OBJECTIONS TO THE NEBULAR THEORY

SPIRAL AND PLANETARY NEBULÆ

The Nebular Theory: Many Applications of the Theory

STAR CLUSTERS AND NEBULÆ

The Second Deluge by Garrett Putman Serviss is part of the HackerNoon Books Series. You can jump to any chapter in this book here . STRANGE FREAKS OF THE NEBULA XIII. STRANGE FREAKS OF THE NEBULA We return to follow the fortunes of Cosmo Versál's Ark. After he had so providentially picked up the crazed billionaire, Amos Blank, and his three companions, Cosmo ordered Captain Arms to bear away southeastward, bidding farewell to the drowned shores of America, and sailing directly over the lower part of Manhattan, and western Long Island. The navigation was not easy, and if the Ark had not been a marvelously buoyant vessel it would not long have survived. At the beginning the heavy and continuous rain kept down the waves, and the surface of the sea was comparatively smooth, but after a while a curious phenomenon began to be noticed; immense billows would suddenly appear, rushing upon the Ark now from one direction and now from another, canting it over at a dangerous angle, and washing almost to the top of the huge ellipsoid of the dome. At such times it was difficult for anybody to maintain a footing, and there was great terror among the passengers. But Cosmo, and stout Captain Arms, remained at their post, relieving one another at frequent intervals, and never entrusting the sole charge of the vessel to any of their lieutenants. Cosmo Versál himself was puzzled to account for the origin of the mighty billows, for it seemed impossible that they could be raised by the wind notwithstanding the fact that it blew at times with hurricane force. But at last the explanation came of itself. Both Cosmo and the captain happened to be on the bridge together when they saw ahead something that looked like an enormous column as black as ink, standing upright on the surface of the water. A glance showed that it was in swift motion, and, more than that, was approaching in a direct line toward the Ark. In less than two minutes it was upon them. The instant that it met the Ark a terrific roaring deafened them, and the rounded front of the dome beneath their eyes disappeared under a deluge of descending water so dense that the vision could not penetrate it. In another half minute the great vessel seemed to have been driven to the bottom of the sea. But for the peculiar construction of the shelter of the bridge its occupants would have been drowned at their posts. As it was they were soaked as if they had been plunged overboard. Impenetrable darkness surrounded them. But the buoyant vessel shook itself, rolled from side to side, and rose with a staggering motion until it seemed to be poised on the summit of a watery mountain. Immediately the complete darkness passed, the awful downpour ceased, although the rain still fell in torrents, and the Ark began to glide downward with sickening velocity, as if it were sliding down a liquid slope. It was a considerable time before the two men, clinging to the supports of the bridge, were able to maintain their equilibrium sufficiently to render it possible to utter a few connected words. As soon as he could speak with reasonable comfort Cosmo exclaimed: "Now I see what it is that causes the billows, but it is a phenomenon that I should never have anticipated. It is all due to the nebula. Evidently there are irregularities of some kind in its constitution which cause the formation of almost solid masses of water in the atmosphere—suspended lakes, as it were—which then plunge down in a body as if a hundred thousand Niagaras were pouring together from the sky. "These sudden accessions of water raise stupendous waves which sweep off in every direction, and that explains the billows that we have encountered." "Well, this nebular navigation beats all my experience," said Captain Arms, wiping the water out of his eyes. "I was struck by a waterspout once in the Indian Ocean, and I thought that that capped the climax, but it was only a catspaw to this. Give me a clear offing and I don't care how much wind blows, but blow me if I want to get under any more lakes in the sky." "We'll have to take whatever comes," returned Cosmo, "but I don't think there is much danger of running directly into many of these downpours as we did into this one. Now that we know what they are, we can, perhaps, detect them long enough in advance to steer out of their way. Anyhow, we've got a good vessel under our feet. Anything but an ark of levium would have gone under for good, and if I had not covered the vessel with the dome there would have been no chance for a soul in her." As a matter of fact, the Ark did not encounter any more of the columns of descending water, but the frequent billows that were met showed that they were careering over the face of the swollen sea in every direction. But there was another trouble of a different nature. The absence of sun and stars deprived them of the ordinary means of discovering their place. They could only make a rough guess as to the direction in which they were going. The gyrostatic compasses gave them considerable assistance, and they had perfect chronometers, but these latter could be of no use without celestial observations of some kind. At length Cosmo devised a means of obtaining observations that were of sufficient value to partially serve their purpose. He found that while the disk of the sun was completely hidden in the watery sky, yet it was possible to determine its location by means of the varying intensity of the light. Where the sun was a concentrated glow appeared, shading gradually off on all sides. With infinite pains Cosmo, assisted by the experience of the captain, succeeded in determining the center of the maximum illumination, and, assuming that to represent the true place of the sun, they got something in the nature of observations for altitude and azimuth, and Captain Arms even drew on his chart "Sumner lines" to determine the position of the Ark, although he smiled at the thought of their absurd inaccuracy. Still, it was the best they could do, and was better than nothing at all. They kept a log going also, although, as the captain pointed out, it was not of much use to know how fast they were traveling, since they could not know the precise direction, within a whole point of the compass, or perhaps several points. "Besides," he remarked, "what do we know of the currents? This is not the old Atlantic. If I could feel the Gulf Stream I'd know whereabouts I was, but these currents come from all directions, and a man might as well try to navigate in a tub of boiling water." "But we can, at least, keep working eastward," said Cosmo. "My idea is first to make enough southing to get into the latitude of the Sahara Desert, and then run directly east, so as to cross Africa where there are no mountains, and where we shall be certain of having plenty of water under our keel. "Then, having got somewhere in the neighborhood of Suez, we can steer down into the region of the Indian Ocean, and circle round south of the Himalayas. I want to keep an eye on those mountains, and stay around the place where they disappear, because that will be the first part of the earth to emerge from the flood and it is there that we shall ultimately make land." "Well, we're averaging eight knots," said the captain, "and at that rate we ought to be in the longitude of the African coast in about twenty days. How high will the water stand then?" "My gages show," replied Cosmo, "that the regular fall amounts to exactly the same thing as at the beginning—two inches a minute. Of course the spouts increase the amount locally, but I don't think that they add materially to the general rise of the flood. Two inches per minute means 4,800 feet in twenty days. That'll be sufficient to make safe navigation for us all the way across northern Africa. We'll have to be careful in getting out into the Indian Ocean area, for there are mountains on both sides that might give us trouble, but the higher ones will still be in sight, and they will serve to indicate the location of the lower ranges already submerged, but not covered deeply enough to afford safe going over them." "All right," said Captain Arms, "you're the commodore, but if we don't hang our timbers on the Mountains of the Moon, or the Alps, or old Ararat, I'm a porpoise. Why can't you keep circling round at a safe distance, in the middle of the Atlantic, until all these reefs get a good depth of water on 'em?" "Because," Cosmo replied, "even if we keep right on now it will probably take two months, allowing for delays in getting round dangerous places, to come within sight of the Himalayas, and in two months the flood will have risen nearly 15,000 feet, thus hiding many of the landmarks. If we should hold off here a couple of months before starting eastward nothing but the one highest peak on the globe would be left in sight by the time we arrived there, and that wouldn't be anything more than a rock, so that with the uncertainty of our navigation we might not be able to find it at all. I must know the spot where Tibet sinks, and then manage to keep in its neighborhood." That ended the argument. "Give me a safe port, with lights and bearings, and I'll undertake to hit it anywhere in the two hemispheres, but blow me if I fancy steering for the top of the world by dead reckoning, or no reckoning at all," grumbled the captain. At night, of course, they had not even the slight advantage that their observations of the probable place of the sun gave them when it was above the horizon. Then they had to go solely by the indications of the compass. Still, they forged steadily ahead, and when they got into what they deemed the proper latitude, they ran for the site of the drowned Sahara. After about a week the billowing motion caused by the descent of the "lakes in the sky" ceased entirely, to their great delight, but the lawless nebula was now preparing another surprise for them. On the ninth night after their departure from their lodgment on the Palisades Cosmo Versál was sleeping in his bunk close by the bridge, where he could be called in an instant, dreaming perhaps of the glories of the new world that was to emerge out of the deluge, when he was abruptly awakened by the voice of Captain Arms, who appeared to be laboring under uncontrollable excitement. "Tumble up quicker'n you ever did in your life!" he exclaimed, his big brown beard wagging almost in Cosmo's face. "The flood's over!" Cosmo sprang out of bed and pulled on his coat in a second. "What do you mean?" he demanded. "Look for yourself," said the captain, pointing overhead. Cosmo Versál glanced up and saw the sky ablaze with stars! The rain had entirely ceased. The surface of the sea was almost as smooth as glass, though rising and falling slowly, with a long, rolling motion. The Ark rode steadily, shivering, like an ocean liner, under the impulse of its engines, and the sudden silence, succeeding the ceaseless roar of the downpour, which had never been out of their ears from the start of the voyage, seemed supernatural. "When did this happen?" he demanded. "It began not more than five minutes ago. I was just saying to myself that we ought to be somewhere near the center of the old Atlantic as it used to be, and wondering whether we had got our course laid right to go fairly between the Canaries and the Cape de Verdes, for I didn't want to be harpooned by Gogo or the Peak of Teneriffe, when all of a sudden there came a lightening in the nor'east and the stars broke out there. "I was so set aback that I didn't do anything for two or three minutes but stare at the stars. Then the rain stopped and a curtain seemed to roll off the sky, and in a minute more it was clear down to the horizon all around. Then I got my wits together and ran to call you." Cosmo glanced around and above, seeming to be as much astonished as the captain had been. He rubbed his huge bald dome and looked all round again before speaking. At last he said: "It's the nebula again. There must be a hole in it." "Its whole bottom's knocked out, I reckon," said the captain. "Maybe it's run out of water—sort o' squeezed itself dry." Cosmo shook his head. "We are not yet in the heart of it," he said. "It is evident to me now that what I took for the nucleus was only a close-coiled spiral, and we're run out of that, but the worst is yet to come. When we strike the center, then we'll catch it, and there'll be no more intermissions." "How long will that be?" inquired Captain Arms. "It may be a week, and it may be a month, though I hardly think it will be so long as that. The earth is going about twelve miles a second—that's more than a million miles a day—directly toward the center of the nebula. It has taken ten days to go through the spiral that we have encountered, making that about ten million miles thick. It's not likely that the gap between this spiral and the nucleus of the nebula is more than thirty million miles across, at the most; so you see we'll probably be in the nucleus within a month, and possibly much less than a month." Captain Arms took a chew of tobacco. "We can get our bearings now," he remarked. "Look, there's the moon just rising, and on my word, she is going to occult Aldebaran within an hour. I'll get an observation for longitude, and another on Polaris for latitude. No running on submerged mountains for us now." The captain was as good as his word, and when his observations had been made and the calculations completed he announced that the position of the Ark was: Latitude, 16 degrees 10 minutes north; longitude, 42 degrees 28 minutes west. "Lucky for us," he exclaimed, "that the sky cleared. If we'd kept on as we were going we'd have struck the Cape de Verdes, and if that had happened at night we'd probably have left our bones on a drowning volcano. We ought to have been ten or twelve degrees farther north to make a safe passage over the Sahara. What's the course now? Are you still for running down the Himalaya mountains?" "I'll decide later what to do," said Cosmo Versál. "Make your northing, and then we'll cruise around a little and see what's best to be done." When day came on, brilliant with sunshine, and the astonished passengers, hurrying out of their bunks, crowded about the now opened gangways and the portholes, which Cosmo had also ordered to be opened, and gazed with delight upon the smooth blue sea, the utmost enthusiasm took possession of them. The flood was over! They were sure of it, and they shook hands with one another and congratulated themselves and hurrahed, and gave cheers for the Ark and cheers for Cosmo Versál. Then they began to think of their drowned homes and of their lost friends, and sadness followed joy. Cosmo was mobbed by eager inquiries wherever he made his appearance. Was it all over for good? Would the flood dry up in a few days? How long would it be before New York would be free of water? Were they going right back there? Did he think there was a chance that many had escaped in boats and ships? Couldn't they pick up the survivors if they hurried back? Cosmo tried to check the enthusiasm. "It's too early for rejoicing," he assured them. "It's only a break in the nebula. We've got a respite for a short time, but there's worse coming. The drowning of the world will proceed. We are the only survivors, except perhaps some of those who inhabited the highlands. Everything less than 2,400 feet above the former level of the sea is now under water. When the flood begins again it will keep on until it is six miles deep over the old sea margins." "Why not go back and try to rescue those who you say may have found safety on the highlands?" asked one. "I have chosen my company," he said, "and I had good reasons for the choice I made. I have already added to the number, because simple humanity compelled me, but I can take no more. The quantity of provisions aboard the Ark is not greater than will be needed by ourselves. If the rest of the world is drowned it is not my fault. I did my best to warn them. Besides, we could do nothing in the way of rescue even if we should go back for that purpose. We could not approach the submerged plateaus. We would be aground before we got within sight of them." These words went far to change the current of feeling among the passengers. When they learned that there would be danger for themselves in the course that had been proposed their humanity proved to be less strong than their desire for self-preservation. Nevertheless, as we shall see, the Ark ultimately went back to America, though not for any reason that had yet been suggested. Meanwhile the unexpected respite furnished by the sudden cessation of the downpour from the sky had other important results, to which we now turn. About HackerNoon Book Series: We bring you the most important technical, scientific, and insightful public domain books. This book is part of the public domain. Garrett Putman Serviss (2005). The Second Deluge. Urbana, Illinois: Project Gutenberg. Retrieved October 2022 https://www.gutenberg.org/cache/epub/9194/pg9194.html This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.org , located at https://www.gutenberg.org/policy/license.html .

STRANGE FREAKS OF THE NEBULA

Explosive and Whirling Nebulæ

Nebullvm 0.3.0 features more deep learning compilers and now supports additional optimization techniques, including quantization and half precision. Nebuly is very excited to announce the new major release nebullvm 0.3.0, where nebullvm’s AI inference accelerator becomes more powerful, stable and covers more use cases. Nebullvm is an open-source library that generates an optimized version of your deep learning model that runs 2 to 10 times faster in inference without performance loss by leveraging multiple deep learning compilers (OpenVINO, TensorRT, ONNX Runtime, TVM, etc.). With the new release 0.3.0, nebullvm can now accelerate inference up to 30x if you specify that you are willing to trade off a self-defined amount of accuracy/precision to get an even lower response time and a lighter model. This additional acceleration is achieved by exploiting optimization techniques that slightly modify the model graph to make it lighter, such as quantization, half precision, distillation, sparsity, etc. Find tutorials and examples on how to use nebullvm, as well as installation instructions in the main . readme of nebullvm library And check below if you want to learn more about: Overview of Nebullvm 0.3.0 Benchmarks How the new Nebullvm0.3.0 API Works Tutorials Overview of Nebullvm With this new version, nebullvm continues in its mission to be: ☘️ Easy-to-use. It takes a few lines of code to install the library and optimize your models. 🔥 Framework agnostic. nebullvm supports the most widely used frameworks (PyTorch, TensorFlow, 🆕ONNX🆕 and Hugging Face, etc.) and provides as output an optimized version of your model with the same interface (PyTorch, TensorFlow, etc.). 💻 Deep learning model agnostic. nebullvm supports all the most popular deep learning architectures such as transformers, LSTM, CNN and FCN. 🤖 Hardware agnostic. The library now works on most CPU and GPU and will soon support TPU and other deep learning-specific ASIC. 🔑 Secure. Everything runs locally on your hardware. ✨ Leveraging the best optimization techniques. There are many inference techniques such as deep learning compilers, 🆕quantization or half precision🆕, and soon sparsity and distillation, which are all meant to optimize the way your AI models run on your hardware. Benchmarks We have tested nebullvm on popular AI models and hardware from leading vendors. The table below shows the inference speedup provided by nebullvm. The speedup is calculated as the response time of the unoptimized model divided by the response time of the accelerated model, as an average over 100 experiments. As an example, if the response time of an unoptimized model was on average 600 milliseconds and after nebullvm optimization only 240 milliseconds, the resulting speedup is 2.5x times, meaning 150% faster inference. A complete overview of the experiment and findings can be found on . this page Overall, the library provides great results, with more than 2x acceleration in most cases and around 20x in a few applications. We can also observe that acceleration varies greatly across different hardware-model couplings, so we suggest you test nebullvm on your model and hardware to assess its full potential. You can find the instructions below. Besides, across all scenarios, nebullvm is very helpful for its ease of use, allowing you to take advantage of inference optimization techniques without having to spend hours studying, testing and debugging these technologies. How the New Nebullvm API Works With the latest release, nebullvm has a new API and can be deployed in two ways. 2–10x acceleration, NO performance loss Option A: If you choose this option, nebullvm will test multiple deep learning compilers (TensorRT, OpenVINO, ONNX Runtime, etc.) and identify the optimal way to compile your model on your hardware, increasing inference speed by 2–10 times without affecting the performance of your model. 2–30x acceleration, supervised performance loss Option B: Nebullvm is capable of speeding up inference by much more than 10 times in case you are willing to sacrifice a fraction of your model’s performance. If you specify how much performance loss you are willing to sustain, nebullvm will push your model’s response time to its limits by identifying the best possible blend of state-of-the-art inference optimization techniques, such as deep learning compilers, distillation, quantization, half precision, sparsity, etc. Performance monitoring is accomplished using the perf_loss_ths (performance loss threshold), and the perf_metric for performance estimation. When a predefined metric (e.g. “accuracy”) or a custom metric is passed as the perf_metric argument, the value of perf_loss_ths will be used as the maximum acceptable loss for the given metric evaluated on your datasets (Option B.1). When no perf_metric is provided as input, nebullvm calculates the performance loss using the default precision function. If the dataset is provided, the precision will be calculated on 100 sampled data (option B.2). Otherwise, the data will be randomly generated from the metadata provided as input, i.e. input_sizes and batch_size (option B.3). Tutorials We suggest testing the library on your AI models right away by following the installation instructions below. If you want to get a first feel of the library’s capabilities or take a look at how nebullvm can be readily implemented in an AI workflow, we have built 3 tutorials and notebooks where the library can be tested on the most popular AI frameworks TensorFlow, PyTorch and Hugging Face. : Accelerate Resnet34 Notebook fast.ai : Accelerate PyTorch YOLO Notebook : Accelerate Hugging Face’s GPT2 and BERT Notebook Explore more Check out the if you want to take a look at nebullvm’s performance and benchmarks, tutorials and notebooks on how to implement nebullvm with ease. And please leave a ⭐ if you enjoy the project and where we chat about nebullvm and AI optimization. GitHub readme join the Discord community Also published here .

New Major Release for Nebullvm Speeds Up AI Inference by 2-30x

Let’s say for example you started a new job as a DevOps/Dev/SRE/etc at a company that created a new smart speaker (think Amazon Echo or Google home), said device gained a lot of success and you quickly find yourself with a million clients, each with a single device at his\hers home, Sounds great right? Now the only problem you have is how do you handle deployments to a million of devices located all across the world? You could go the way most old school vendors do it by releasing a package for the end user to download and install himself on the company website but at this day and age this will quickly lose you customers to the competition who doesn’t have such high maintenance needs. You could create a self updating system built into your codebase but that will require a lot of maintenance and man hours from the development team & even then will likely lead to problems and failures down the road. You could containerize the codebase, create on each smart speaker a single server Kubernetes cluster and create a huge federated cluster out of all of them (as Kubernetes doesn’t support this scale nor latency tolerant workers this is required) but that will lead to huge costs on all the resources wasted only to run all said clusters. You could use — which was designed to solve exactly this kind of distributed orchestration needs. Nebula Container Orchestrator As you may have guessed from the title I want to discuss about the last option from the list. aims to help devs and ops treat IoT devices just like distributed Dockerized apps. It aim is to act as Docker orchestrator for IoT devices as well as for distributed services such as CDN or edge computing that can span thousands (or even millions) of devices worldwide and it does it all while being open-source and completely free. Nebula Container Orchestrator Different requirements leads to different orchestrators When you think about it a distributed orchestrator has the following requirements: It needs to be latency tolerant — if the IoT devices are distributed then each will connect to the orchestrator through the Internet at a connection that might not always be stable or fast. It needs to scale out to handle thousands (and even hundreds of thousands) of IoT devices — massive scale deployments are quickly becoming more and more common. It needs to run on multiple architectures — a lot of IoT devices uses ARM boards. It needs to be self healing — you don’t want to have to run across town to reset a device every time there is a little glitch do you? Code needs to be coupled to the hardware — if your company manufacture the smart speaker in the example mentioned above & a smart fridge you will need to ensure coupling of the code to the device it’s intended to run on (no packing different apps into the same devices in the IoT use case). This is quite different from the big Three orchestrators (Kubernetes, Mesos & Swarm) which are designed to pack as many different apps\microservices onto the same servers in a single (or relatively few) data centers and as a result non of them provide truly latency tolerant connection and the scalability of Swarm & Kubernetes is limited to a few thousands workers. Nebula architecture was designed with stateless RESTful Manger microservice to provide a single point to manage the clusters as well as providing a single point which all containers check for updates with a Kafka inspired Monotonic ID configuration updates in a pull based methodology, this ensure that changes to any of the applications managed by Nebula are pulled to all managed devices at the same time and also ensures that all devices will always have the latest version of the configuration(thanks to the monotonic ID), all data is stored in MongoDB which is the single point of truth for the system, on the workers side it’s based around a worker container on each devices that is in charge of starting\stopping\changing the other containers running on that device, due to the design each component can be scaled out & as such Nebula can grow as much as you require it. Nebula you can read more about Nebula architecture at https://nebula.readthedocs.io/en/latest/architecture/ Nebula features As it was designed from the ground up to support distributed systems Nebula has a few neat features that allows it to control distributed IoT systems: Designed to scale out on all of it’s components (IoT devices, API layer, & Mongo all scale out) Able to manage millions of IoT devices Latency tolerant — even if a device goes offline it will be re-synced when he gets back online Dynamically add/remove managed devices Fast & easy code deployments, single API call with the new container image tag (or other configuration changes) and it will be pushed to all devices of that app. Simple install —MongoDB & a stateless API is all it takes for the management layer & a single container with some envvars on each IoT device you want to manage takes care of the worker layer Single API endpoint to manage all devices Allows control of multiple devices with the same Nebula orchestrator (multiple apps & device_groups) Not limited to IoT, also useful for other types of distributed systems API, Python SDK & CLI control available A little example The following command will install an cluster for you to play on and will create an example app as well, requires Docker, curl & docker-compose installed: Nebula curl -L "https://raw.githubusercontent.com/nebula-orchestrator/docs/master/examples/hello-world/start_example_nebula_cluster.sh" -o start_example_nebula_cluster.sh && sudo sh start_example_nebula_cluster.sh But let’s go over what this command does to better understand the process: The scripts downloads and runs a docker-compose.yml file which creates: a) A MongoDB container — the backend DB where Nebula apps current state is saved. b) A manager container — A RESTful API endpoint, this is where the admin manages Nebula from & where devices pulls the latest configuration state from to match against their current state c) A worker container — this normally runs on the IoT devices, only one is needed on each device but as this is just an example it runs on the same server as the management layer components runs on. It’s worth mentioning the “DEVICE_GROUP=example” environment variable set on the worker container, this DEVICE_GROUP variable controls what nebula apps will be connected to the device (similar to a pod concept in other orchestrators). 2. The script then waits for the API to become available. 3. Once the API is available the scripts sends the following 2 commands: curl -X POST \http://127.0.0.1/api/v2/apps/example \-H 'authorization: Basic bmVidWxhOm5lYnVsYQ=='  \                            -H 'cache-control: no-cache'    \-H 'content-type: application/json'    \                            -d '{"starting_ports": [{"81":"80"}],"containers_per": {"server": 1},"env_vars": {},"docker_image" : "nginx","running": true,"volumes": [],"networks": ["nebula"],"privileged": false,"devices": [],"rolling_restart": false}' This command creates an app named “example” and configures it to run an nginx container to listen on port 81 , as you can see it can also control other parameters usually passed to the docker run command such as envvars or networks or volume mounts. curl -X POST \http://127.0.0.1/api/v2/device_groups/example \                                 -H 'authorization: Basic bmVidWxhOm5lYnVsYQ==' \                                 -H 'cache-control: no-cache' \-H 'content-type: application/json' \                                 -d '{"apps": ["example"]}' This command creates a device_group that is also named “example” & attaches the app named “example” to it, 4. After the app & device_groups arecreated on the nebula API the worker container will pick it up the changes to the device_group which is been confiugred to be part of (“example” in this case) and will start an Nginx container on the server, you can run “docker logs worker” to see the Nginx container being downloaded before it starts (this might take a bit if your on a slow connection). and after it’s completed you can access on your browser to see it running http://<server_exterior_fqdn>:81/ Now that we have a working Nebula system running we can start playing around with it to see it’s true strengths: We can add more remote workers by running a worker container on them: sudo docker run -d --restart unless-stopped -v /var/run/docker.sock:/var/run/docker.sock --env DEVICE_GROUP=example --env REGISTRY_HOST=https://index.docker.io/v1/ --env MAX_RESTART_WAIT_IN_SECONDS=0 --env NEBULA_MANAGER_AUTH_USER=nebula --env NEBULA_MANAGER_AUTH_PASSWORD=nebula --env NEBULA_MANAGER_HOST=<your_manager_server_ip_or_fqdn> --env NEBULA_MANAGER_PORT=80 --env nebula_manager_protocol=http --env NEBULA_MANAGER_CHECK_IN_TIME=5 --name nebula-worker nebulaorchestrator/worker It’s worth mentioning that a lot of the envvars passed through the command above are optional (with sane defaults) & that there is no limit on how many devices we can run this command on, at some point you might have to scale out the managers and\or backend DB but those are not limited as well. We can change the container image on all devices with a single API call, let’s for example replace the container image to Apache to simulate that curl -X PUT \ v2/ \ http://127.0.0.1/api/ apps/example/update -H ‘authorization: Basic bmVidWxhOm5lYnVsYQ==’ \ -H ‘cache-control: no-cache’ \ -H ‘content-type: application/json’ \ -d ‘{ “docker_image”: “httpd:alpine” }’ Similarly we can also update any parameter of the app such as env_vars, privileged permissions, volume mounts, etc, — the full list of API endpoints as well as the Python SDK & the CLI is available at documentation page at https://nebula.readthedocs.io/en/latest/ Hopefully this little guide allowed you to see the need of an IoT docker orchestrator and it’s use case & should you find yourself interested in reading more about it you can visit site at or skip right ahead to the documentation at Nebula Container Orchestrator https://nebula-orchestrator.github.io/ https://nebula.readthedocs.io

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