The universe, at the instant of the Big Bang 13.7 billion years ago, was an 'infinitely small dot' containing its total (and constant) energy. At that point — just before space-time came into existence — some of the energy within our energy-only 'dot universe', for some unknown reason, began to convert into matter, creating at the same time the energy-matter-space-time framework we perceive as our universe...

The Magnificent Dot.

After a lot of conjecture and speculation and theorizing, pretty much all working astronomers believe in this so-called Big Bang picture, in which the universe started out really small at some time roughly 15 billion years ago. It exploded. All of this stuff came out of it. But the thing that's so hard for us to picture is, the explosion of something that started the size of a dot, all the matter and all the energy, but in addition, all the space was in there. And when the thing exploded, not only did all this matter and energy come out of this explosion, but all the space came out of it too. So we were in there. And the concept of what was outside the dot before the dot exploded, it turns out is a non-concept because all the space was inside there too. Imponderable stuff. And so the subject of cosmology, the origin of the universe, and all that kind of stuff is a kind of mixture of science and philosphy, a very interesting subject and very hard to come to grips with.

-- Frank Bash - Director, McDonald Observatory

Moon-struck, A Jules Vernian Account

The Queen of Night, from her relative proximity and the spectacle rapidly renewed of her different phases, at first divided the attention of the inhabitants of the earth with the sun; but the sun tires the eyesight, and the splendour of its light forces its admirers to lower their eyes.

The blonde Phoebe, more humane, graciously allows herself to be seen in her modest grace; she is gentle to the eye, not ambitious, and yet she sometimes eclipses her brother the radiant Apollo, without ever being eclipsed by him. The Mahommedans understood what gratitude they owed to this faithful friend of the earth, and they ruled their months at 29-1/2 days on her revolution.

The first people of the world dedicated particular worship to this chaste goddess. The Egyptians called her Isis, the Phoenicians Astarte, the Greeks Phoebe, daughter of Jupiter and Latona, and they explained her eclipses by the mysterious visits of Diana and the handsome Endymion. The mythological legend relates that the Nemean lion traversed the country of the moon before its apparition upon earth, and the poet Agesianax, quoted by Plutarch, celebrated in his sweet lines its soft eyes, charming nose, and admirable mouth, formed by the luminous parts of the adorable Selene.

But though the ancients understood the character, temperament, and, in a word, moral qualities of the moon from a mythological point of view, the most learned amongst them remained very ignorant of selenography.

Several astronomers, however, of ancient times discovered certain particulars now confirmed by science. Though the Arcadians pretended they had inhabited the earth at an epoch before the moon existed, though Simplicius believed her immovable and fastened to the crystal vault, though Tacitus looked upon her as a fragment broken off from the solar orbit, and Clearch, the disciple of Aristotle, made of her a polished mirror upon which were reflected the images of the ocean — though, in short, others only saw in her a mass of vapours exhaled by the earth, or a globe half fire and half ice that turned on itself, other savants, by means of wise observations and without optical instruments, suspected most of the laws that govern the Queen of Night.

Thus Thales of Miletus, B.C. 460, gave out the opinion that the moon was lighted up by the sun. Aristarchus of Samos gave the right explanation of her phases. Cleomenus taught that she shone by reflected light. Berose the Chaldean discovered that the duration of her movement of rotation was equal to that of her movement of revolution, and he thus explained why the moon always presented the same side. Lastly, Hipparchus, 200 years before the Christian era, discovered some inequalities in the apparent movements of the earth's satellite.

These different observations were afterwards confirmed, and other astronomers profited by them. Ptolemy in the second century, and the Arabian Aboul Wefa in the tenth, completed the remarks of Hipparchus on the inequalities that the moon undergoes whilst following the undulating line of its orbit under the action of the sun. Then Copernicus, in the fifteenth century, and Tycho Brahe, in the sixteenth, completely exposed the system of the world and the part that the moon plays amongst the celestial bodies.

At that epoch her movements were pretty well known, but very little of her physical constitution was known. It was then that Galileo explained the phenomena of light produced in certain phases by the existence of mountains, to which he gave an average height of 27,000 feet.

After him, Hevelius, an astronomer of Dantzig, lowered the highest altitudes to 15,000 feet; but his contemporary, Riccioli, brought them up again to 21,000 feet.

Herschel, at the end of the eighteenth century, armed with a powerful telescope, considerably reduced the preceding measurements. He gave a height of 11,400 feet to the highest mountains, and brought down the average of different heights to little more than 2,400 feet. But Herschel was mistaken too, and the observations of Schroeter, Louville, Halley, Nasmyth, Bianchini, Pastorff, Lohrman, Gruithuysen, and especially the patient studies of MM. Boeer and Moedler, were necessary to definitely resolve the question. Thanks to these savants, the elevation of the mountains of the moon is now perfectly known. Boeer and Moedler measured 1,905 different elevations, of which six exceed 15,000 feet and twenty-two exceed 14,400 feet. Their highest summit towers to a height of 22,606 feet above the surface of the lunar disc.

At the same time the survey of the moon was being completed; she appeared riddled with craters, and her essentially volcanic nature was affirmed by each observation. From the absence of refraction in the rays of the planets occulted by her it is concluded that she can have no atmosphere. This absence of air entails absence of water; it therefore became manifest that the Selenites, in order to live under such conditions, must have a special organisation, and differ singularly from the inhabitants of the earth.

Lastly, thanks to new methods, more perfected instruments searched the moon without intermission, leaving not a point of her surface unexplored, and yet her diameter measures 2,150 miles; her surface is one-thirteenth of the surface of the globe, and her volume one-forty-ninth of the volume of the terrestrial spheroid; but none of her secrets could escape the astronomers' eyes, and these clever savants carried their wonderful observations still further.

Thus they remarked that when the moon was at her full the disc appeared in certain places striped with white lines, and during her phases striped with black lines. By prosecuting the study of these with greater precision they succeeded in making out the exact nature of these lines. They are long and narrow furrows sunk between parallel ridges, bordering generally upon the edges of the craters; their length varied from ten to one hundred miles, and their width was about 1,600 yards. Astronomers called them furrows, and that was all they could do; they could not ascertain whether they were the dried-up beds of ancient rivers or not. The Americans hope, some day or other, to determine this geological question. They also undertake to reconnoitre the series of parallel ramparts discovered on the surface of the moon by Gruithuysen, a learned professor of Munich, who considered them to be a system of elevated fortifications raised by Selenite engineers. These two still obscure points, and doubtless many others, can only be definitely settled by direct communication with the moon.

--From the Earth to the Moon, Jules Verne, Chapter

An Account of Formation of the Solar System in Jules Verne

An observer endued with an infinite range of vision, and placed in that unknown center around which the entire world revolves, might have beheld myriads of atoms filling all space during the chaotic epoch of the universe. Little by little, as ages went on, a change took place; a general law of attraction manifested itself, to which the hitherto errant atoms became obedient: these atoms combined together chemically according to their affinities, formed themselves into molecules, and composed those nebulous masses with which the depths of the heavens are strewed. These masses became immediately endued with a rotary motion around their own central point. This center, formed of indefinite molecules, began to revolve around its own axis during its gradual condensation; then, following the immutable laws of mechanics, in proportion as its bulk diminished by condensation, its rotary motion became accelerated, and these two effects continuing, the result was the formation of one principal star, the center of the nebulous mass.

By attentively watching, the observer would then have perceived the other molecules of the mass, following the example of this central star, become likewise condensed by gradually accelerated rotation, and gravitating round it in the shape of innumerable stars. Thus was formed the Nebulae, of which astronomers have reckoned up nearly 5,000.

Among these 5,000 nebulae there is one which has received the name of the Milky Way, and which contains eighteen millions of stars, each of which has become the center of a solar world.

If the observer had then specially directed his attention to one of the more humble and less brilliant of these stellar bodies, a star of the fourth class, that which is arrogantly called the Sun, all the phenomena to which the formation of the Universe is to be ascribed would have been successively fulfilled before his eyes. In fact, he would have perceived this sun, as yet in the gaseous state, and composed of moving molecules, revolving round its axis in order to accomplish its work of concentration. This motion, faithful to the laws of mechanics, would have been accelerated with the diminution of its volume; and a moment would have arrived when the centrifugal force would have overpowered the centripetal, which causes the molecules all to tend toward the center.

Another phenomenon would now have passed before the observer's eye, and the molecules situated on the plane of the equator, escaping like a stone from a sling of which the cord had suddenly snapped, would have formed around the sun sundry concentric rings resembling that of Saturn. In their turn, again, these rings of cosmical matter, excited by a rotary motion about the central mass, would have been broken up and decomposed into secondary nebulosities, that is to say, into planets. Similarly he would have observed these planets throw off one or more rings each, which became the origin of the secondary bodies which we call satellites.

Thus, then, advancing from atom to molecule, from molecule to nebulous mass, from that to principal star, from star to sun, from sun to planet, and hence to satellite, we have the whole series of transformations undergone by the heavenly bodies during the first days of the world.

The sun seems lost amidst the immensities of the stellar universe, and yet it is related, by actual theories of science, to the nebula of the Milky Way. Centre of a world, and small as it appears amidst the ethereal regions, it is still enormous, for its size is 1,400,000 times that of the earth. Around it gravitate eight planets, struck off from its own mass in the first days of creation. These are, in proceeding from the nearest to the most distant, Mercury, Venus, the Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Between Mars and Jupiter circulate regularly other smaller bodies, the wandering debris, perhaps, of a star broken up into thousands of pieces, of which the telescope has discovered eighty-two at present. Some of these asteroids are so small that they could be walked round in a single day by going at a gymnastic pace.

Now, of those attendant bodies which the sun maintains in their elliptical orbits by the great law of gravitation, some few in turn possess satellites. Uranus has eight, Saturn eight, Jupiter four, Neptune possibly three, and the Earth one. This last, one of the least important of the entire solar system, we call the Moon; and it is she whom the daring genius of the Americans professed its intention of conquering.

-- From the Earth to the Moon, Jules Verne, Chapter 5

Big Bang and the Fractal Universe

The Big Bang theory did not allow much room for optimism concerning our future. However, 15 years ago, physicists realized that the theory should be modified because it was plagued by many complicated problems related not only to our future, but to our past and present as well. For example, the standard Big Bang theory combined with the modem theory of elementary particles predicts the existence of many superheavy stable particles carrying magnetic charge: magnetic monopoles. These objects have a typical mass times that of the proton. According to the standard Big Bang theory, monopoles should appear at the very early stages of the evolution of the Universe, and they should now be as abundant as protons. In that case, the mean density of matter in the Universe would be about 15 orders of magnitude higher than its present value of about 10-29 g/cm3

Originally, we hoped that this problem would disappear when more complicated theories of elementary particles were considered. Unfortunately, despite the rapid development of elementary particle physics, the monopole problem remained unsolved, and many new ones have been added: the gravitino problem, Polonyi field problem, domain wall problem, axion window problem, and so on. Physicists were forced to look more attentively at the basic assumptions of the standard cosmological theory. We have found that many of the assumptions are very suspicious.

The main problem of the Big Bang cosmology is the very existence of the Big Bang. What was before the Big Bang? Where did the Universe come from? If space-time did not exist for times less than 0, how could everything appear from nothing? What appeared first: the Universe or the laws determining its evolution? When we were born, the laws determining our development were written in the genetic code of our parents. But where were the laws of physics written when there was no Universe?

The problem of cosmological singularity still remains the most difficult problem of modem cosmology. However, we can now look at it from a totally different point of view. At school we are taught that two parallel lines never cross. However, general relativity tells us that our Universe is curved. The Universe may be open, in which case parallel lines diverge from one another, or it may be closed, and parallel lines cross each other like meridian lines on a globe. The only natural length parameter in general relativity is the Planck length lp approximately 10-33 cm. At smaller distances, the standard concept of space becomes inapplicable because of large quantum fluctuations. Therefore, we would expect our space to be very curved, with a typical radius of curvature about 10-33 cm. We see, however, that our Universe is just about flat on a scale of 1028 cm, the radius of the observable part of the Universe. The results of our observations differ from our theoretical expectations by more than 60 orders of magnitude!

Why are there so many different people on Earth? Well, Earth is large, so it can accommodate a lot of people. But why is Earth so large? (In fact, it is extremely small compared with the whole Universe.) Why is the Universe so large? A typical answer is that the Universe is large because it is a Universe, so it should be large, should it not? However, let us consider the Universe of a typical size lp just emerging from the Big Bang. Let us assume that this Universe had the greatest possible density at which we can still describe it in terms of usual space and time. This is the so-called Planck density, 1094 g/cm3, which corresponds to matter consisting of particles displaced at the Planck distance lp from each other. We do not know how to describe matter with a greater density. But if we take the Planck size universe with the Planck density, we can easily understand, by definition of the Planck density, that such a universe can contain only a few particles. The standard assumption of the Big Bang cosmology is that the total number of elementary particles in the Universe almost does not change during the expansion of the Universe. Thus, a typical universe should contain one particle, maybe ten particles, but not 1088 particles, which is the number contained in the part of the Universe we see now. This is a contradiction by 88 orders of magnitude.

The standard assumption of the Big Bang theory is that all parts of the Universe began their expansion simultaneously, at the moment t = 0. But how could different parts of the Universe synchronize the beginning of their expansion if they did not have any time for it? Who gave the command?

Our Universe, on a very large scale, is extremely homogeneous. On a scale of 1010 light years, the distribution of matter departs from perfect homogeneity by less than 1 part in 100,000. For a long time nobody had any idea why the Universe was so homogeneous. But those who do not have good ideas sometimes have good principles. One of the cornerstones of the standard cosmology was the cosmological principle, which asserts that the Universe must be homogeneous. However, the Universe contains stars, galaxies, and other important deviations from homogeneity. We have two opposite problems to solve. First, we must explain why our Universe is so homogeneous, and then we should suggest some mechanism that produced galaxies.

All these problems (and others) are extremely difficult. That is why it is very encouraging that most of these problems can be resolved in the context of one simple theory of the evolution of the Universe — the inflationary scenario. Meanwhile, some of its consequences are even more surprising. Instead of the Universe looking like a single expanding ball created in the Big Bang, we envisage it now as a huge, growing fractal consisting of many inflating balls that are producing new balls that are producing new balls, ad infinitum.

--The Origin and Evolution of the Universe, Ben Zuckerman, Matthew Arnold Malkan, Chapter 7: Future of the Universe

Big Bang: Limitations of the Theory

The Big Bang theory is the accepted theory about the evolution of the Universe over billions of years. However, the theory is often misunderstood as dealing with an initial explosion. Judging by the title of Steven Weinberg's popular exposition, The First Three Minutes, it seems as if the Universe has a beginning and as if we can describe processes right from the very first instant.

The Big Bang theory is a combination of two theoretical systems describing the processes happening to the contents of the Universe: general relativity for spacetime and quantum theory for matter. This implies three limits to the Big Bang theory:

On the left the Big Bang model is depicted as a cone, with each horizontal slice representing the three-dimensional universe at a given moment of time. On the right the major uncertainties are stressed.

1. Current theories about matter are valid only up to a finite temperature, and hence valid only after the first fraction of a second following the Singularity, the initial moment entailed by general relativity. This implies a, perhaps temporary, epistemological boundary to the domain where the Big Bang theory can be trusted. Further speculations have to deal with temperatures and densities for which particle physics is not yet well established.

2. Closer to the Singularity there comes a moment, presumably the ‘Planck Time’—a number constructed from the fundamental constants of quantum theory and gravity, about 10-43 seconds after the initial Singularity—when general relativity must be replaced by a quantum theory of gravity. Theories of space and time applicable before the Planck Time are not known; even the meaningfulness of 'space' and 'time' is uncertain. (Which is troublesome; once time is no longer meaningful, it becomes unclear what can be meant by 'before'.)

3. The initial Singularity itself is a third limit, at least if there is such an initial Singularity. The Big Bang theory results in unrealistic numbers, like infinite density and so on. For some time it was assumed that the unrealistic breakdown of the solutions was a feature of idealizations made in the calculations, for instance the assumption of perfect homogeneity. However, it has since been shown that such peculiarities are unavoidable in general relativity, once certain very general assumptions are made, like causality and a positive energy density. On the other hand, general relativity itself is probably invalid in the moments before the Planck Time. Whether there is such a singular moment in a theory of quantum gravity which is to supersede general relativity cannot be decided a priori, before such a theory of quantum gravity has been proposed.

The first and second limits are clearly limits to our present knowledge, the third, the Singularity, seems to be an edge of reality, but is hidden behind the other two.

- 'Beyond the Big Bang: Quantum Cosmologies and God', Willem B. Drees, Chapter 2: Quantum Cosmologies and the Beginning.

Brahe and Kepler

Tycho Brahe had a love-hate relationship with his brash young assistant Johannes Kepler. Over the year and a half they worked together, Kepler and Brahe fought, Kepler left in angry fits or Brahe would order him to leave, then one or the other would beg to work together again. For some reason they needed each other. Brahe's observations of the universe were unsurpassed throughout the world. Kepler wanted access to them to devise better descriptions of how the heavens worked. Brahe, in turn, needed Kepler's brilliant math skills to help prove his own theories.

But they rubbed each other the wrong way, and Brahe wanted to keep him occupied and out of his hair. "Describe for me the orbit of Mars," he told Kepler in 1600, knowing full well that all the greats of history had wrestled with the prickly warrior planet and come up short.

"Give me a week," replied Kepler.

Kepler was overconfident. It would take him eight years to hammer out the orbit, but when he did, he turned Ptolemy's model on its head. He described the way the planets move with three laws that are still taught in introductory physics classes around the world.

Brahe and Kepler's names aren't well known outside the world of astronomy, but their contributions to science were as crucial as those of the more famous Copernicus and Galileo. In fact, some historians argue that the vision of a sun-centered cosmos that Copernicus devised in the 1500s wasn't so revolutionary—although Copernicus championed a moving earth, he clung unquestioningly to Aristotelian ideals such as circular motion. He wrote: "It is altogether absurd that a heavenly body should not always move with a uniform velocity in a perfect circle." In fact, Copernicus tried to connect to the ancients by writing his most important treatise, De Revolutionibus Orbium (The Revolutions of the Celestial Orbs), which echoed Ptolemy's Amalgaest, with each chapter of his book correlating to a chapter in Ptolemy. Moreover, Copernicus cited pre-Aristotelian philosophers such as the Pythagoreans to support his ideas for a sun-centered universe. To overturn Aristotle, he reached back even farther in time—not what one would call really taking a leap into the unknown.

Not to belittle Copernicus—he certainly provided a jump from the status quo. He also used a new concept to choose his theory: simplicity. Or even, one could say, beauty. The austerity of the simple Copernican system gave it an aesthetically appealing quality missing from Ptolemy's rings within rings. In modern times, scientists have almost deified this simplicity concept, known as Occam's Razor. If two theories fit the data, choose the simpler of the two. If you can explain the cosmos with just a few orbits instead of all those epicycles, then stick to the former.

But, alas for Copernicus, his simple ring system of planets orbiting a slightly off-center sun didn't correspond to reality substantially better than Ptolemy's model. Sticky Mars was still out of whack. Copernicus's De Revolutionibus Orbium was edited by a man named Rheticus, who, legend has it, became so frustrated with mapping the path of the red planet that he called upon the spirit world to help. A demon appeared, threw him against a couple of walls, and shouted, “Thus are the motions of Mars!"

Until someone decided to map the orbit of Mars first and then determine the math that described it instead of the other way around, no one was going to produce a complete model of the sky. That was not something Copernicus, firmly enmeshed in the philosophies of his day, was capable of doing. It was Brahe and Kepler, with their willingness to really observe what they were studying, to insist that the observations match their theories, who nudged cosmology a little closer to modern-day "science."

That these two characters—for they were definitely both characters—had the chance to come together and collaborate is almost beyond belief. Brahe was of Danish nobility, Kepler of the German lower class, but together they provided the most accurate depictions of the stars until that time.

--'The Big Bang Theory: What It Is, Where It Came From, and Why It Works', Karen C. Fox

Humans Look into the Universe

Humans have always looked into the night sky and wondered about the mysteries hidden in its depths. Developing our modern understanding of the universe and its origins has taken thousands of years, with many wrong turns and detours along the way.

Until the 1500s, most natural philosophers (the early scientists) thought our planet was the center of the universe. If Earth were moving through space, they reasoned, we would be thrown off or blown away by violent winds. In their theory, stars and planets circled Earth, held in a series of invisible crystal spheres. It certainly looked like the natural philosophers were right. After all, as we gaze up at the sky, don't we seem to be standing still? The Moon, the Sun, and the stars travel across the sky in great circles above us.

This geocentric (Earth-centered) theory survived for almost two thousand years. It was supported in the writings of the Greek philosopher Aristotle around 350 BCE. About five hundred years later, in the second century A.D., the Egyptian astronomer Ptolemy wrote a detailed explanation of why Earth must be at the center of the universe.

Not all early astronomers agreed with this theory, however. Aristarchus of Samos, a Greek astronomer who lived from about 310-230 BCE thought Earth revolved around the Sun. But for two thousand years, Aristotle's geocentric theory was accepted by most scientists. The powerful Catholic Church, which relied on his teachings, also supported the geocentric idea because some biblical passages suggested that the Sun moved while Earth remained in one place. Few people were willing to dispute the church's favored theory. Anyone who challenged it was in danger of being imprisoned or even executed.

We have since learned that our planet is just a tiny speck circling an ordinary star, somewhere in a vast ocean of stars. Our understanding of the universe began to change around 1500, with the work of Polish astronomer Nicolaus Copernicus. Copernicus believed Earth and the other planets traveled in circular orbits around the Sun. His theory more accurately described the paths of the planets and stars in the sky than the geocentric theory did. But Copernicus's theory also removed Earth from its special place at the center of the universe.

Copernicus knew his idea was contrary to church teachings. Revealing it could be punished by death. He didn't publish his revolutionary idea until the very last days of his life. Copernicus's idea has been an essential part of cosmology ever since. The Copernican principle says Earth does not occupy a special, central time or place in the universe.

In 1609 Austrian astronomer Johannes Kepler improved upon Copernicus's idea. Kepler used mathematics to analyze the orbits of the known planets and found that they all follow the same rules of motion. The planets, he discovered, travel around the Sun in elliptical (oval) orbits, not circles. Each moves more slowly as its orbit takes it farther from the Sun, then speeds up again as it moves closer. Kepler also found that a planet's speed is proportional to its distance from the Sun. The farther a planet is from the Sun, the more slowly it moves. In short, the motions of the heavenly bodies follow regular mathematical rules.

In 1610 the Italian scientist Galileo Galilei provided additional support for Copernicus's theory. The telescope had recently been invented, and Galileo made his own improvements on the instrument. With his new telescope, Galileo found four moons orbiting Jupiter. These moons were further proof that not every object in the sky circled Earth. Galileo's discovery made it easier to believe that planets could revolve around the Sun, much as the moons revolved around Jupiter.

Just as important, Galileo first explained the idea of inertia. Inertia is the property of all matter to remain in motion (or at rest) unless a force acts to change its motion. One such force is friction—the force that slows the motion of two surfaces that touch each other. Galileo realized that in empty space, without friction, an object like a star or a planet could keep moving forever. Through Galileo's work, astronomers came to understand that everything in the universe is in constant motion.

The key to understanding the motion of the stars and planets became available in 1687, when English physicist Isaac Newton published his laws of motion and the law of universal gravitation. Newton's laws predicted the motion of objects on Earth. Even more important, the same laws calculated the motion of the planets. According to Newton's laws, an apple falling to Earth and the Moon falling in its orbit around Earth both follow the same rules. Newton realized that the Moon constantly falls toward Earth, but the Moon also moves forward fast enough to keep falling past Earth. That's how it maintains a constant orbit instead of colliding with Earth. The same laws of physics apply to the Sun, Earth, and the other planets. This may seem obvious to us. But in the 1600s, Newton's laws were revolutionary. They allowed scientists to explain events happening far from our own world.

Astronomers continued to gather more information about the stars. Larger, more powerful telescopes let them see farther and farther into space. One of the objects that had puzzled early astronomers was the Milky Way. What was this faint streak of light painted across the night sky? Galileo was the first astronomer to see individual stars in the Milky Way. In 1750 English astronomer Thomas Wright proposed that the entire Milky Way was actually a broad band of many stars.

Astronomers were also finding small, fuzzy patches of light scattered across the sky. They called these objects nebulae, from the Latin word for "cloud." In 1755 the German philosopher Emmanuel Kant suggested nebulae might be "island universes," or galaxies, made up of many individual stars. The word galaxy comes from the Greek word for "milk." The name we use for these large, spinning clouds of stars comes from the ancient name for our own galaxy.

British astronomer William Herschel studied nebulae through his telescope. He made a careful catalog of more than two thousand nebulae he found across the sky. Herschel confirmed Kant's hypothesis about the composition of these objects in 1785. His powerful telescope showed individual stars in several nebulae. In the late 1700s, Herschel also studied the movement of binary stars—pairs of stars that orbit one another. He discovered that their orbits follow Newton's laws. This proved that Newton's laws were truly universal—they could be applied to objects anywhere in the universe.

By the mid-1800s, astronomers were using photographic film to study the heavens. They kept their camera lenses open for long periods of time. This gathered much more faint light than you could with a simple snapshot. These long exposures displayed many thousands of stars invisible to the naked eye.

--The Big Bang, by Paul Fleischer