Will man one day have the ability to travel through time? Let us begin by examining the effects of such an accomplishment.

If we could travel to various time periods, we would most likely alter the entire time line irreparably. To put it simply, our existence would be a mess! There would be disruptions in temporal continuity. Many people would probably be "wiped out of existence" all together! There are still many other paradoxes that I have not yet mentioned, but shall explain in what follows.

If one was to travel back in time and meet himself, what would happen? Would this individual be divided into 2 separate, yet identical beings? Or would the person grow rapidly younger and maybe even loose his memory of the time in which he was originally living?

Could a person go back to a time before he was born? I believe that many problems would arise if this were attempted. First of all, how could the person exist, yet not exist at the same time? Here again is the possibility of growing younger while time traveling; going from your current age to a single cell, and then into NONEXISTENCE.

Let us say, for example, that someone CAN travel to another time. This raises another question. If someone was in another time for 2 days and decided to go back to the time period from which he came, would 2 days have passed in his original time? Or, would he "disappear", spend these 2 days in the other time, and "reappear" instantaneously? I believe that it would be NEARLY instantaneous, though there may be a millisecond or microsecond difference.

And what about the sensation of time travel? How could one handle the extreme conditions and sensations of it? Unless there is some sort of protective shield, I do not believe a human could handle the transient period from one time to another.

Another thing; if time travel WERE created, wouldn't this present time line be messed up already. It seems that there are no massive sudden disappearances of people or parts of the time line for that matter that I know of! Unless, that is, these temporal paradoxes that we're all so worried about never happen. Maybe there are people right now walking among us from other times, and not saying anything about it. Maybe Tesla & Einstein were from other times!

The next topic that comes to mind is the future. First of all, is/ are future events presently indefinite? I don't believe they are. I think that many major events in time are "planned" and definite, though we cannot know them now. Let's just say they WERE indefinite, just for the sake of argument. If we attempt to go into the future, we may just hit some kind of barrier. If we try to go past this barrier, we may be plummeted head-on into eternal non-existence in this plane. If the time line is planned, the alteration of it would have drastic repercussions.

In my opinion, I believe that time travel shall never come into being. Let's leave the time line up to the supreme being.

The breakthrough that eventually allowed scientists to explain the northern and southern lights (bands of bright color also known as aurora borealis and aurora australis), happened by accident.

In 1859, English astronomer Richard Carrington was sketching sunspots when he witnessed a large solar flare. He soon learned that a British observatory measured a simultaneous fluctuation in the Earth's magnetic field caused by the flare.

Eighteen hours later, one of the most dramatic displays of northern and southern lights on record began. Scientists still could not explain what caused auroras, but they were now confident it had something to do with energy from the sun.

A century later, observations from spacecraft confirmed that auroras occur when electrically charged "solar wind"--a stream of electrons and protons released by the sun--disrupts the Earth's magnetic field. Some of the solar energy slips through the field and enters the upper atmosphere, causing oxygen and nitrogen molecules to glow--just as electricity makes fluorescent lamps glow. The colors in auroras vary depending on the gas that's involved, which is also true of fluorescent lamps. Oxygen molecules tend to emit the greenish light that's common in auroras. Nitrogen is responsible for red, blue, and lavender hues.

Auroras are most common near the North and South Poles, because that's where it is easiest for the solar wind to break through the Earth's magnetic field (they're reported less often in the south because that part of the globe is less populated). In rare cases, the auroral displays stretch into southern parts of Europe and the United States, but that happens only a few times per century during the strongest solar bombardments. The solar flare that Carrington saw in 1859, for instance, triggered a solar storm so strong that the northern lights were visible in Puerto Rico.

Like Alfred Russell Wallace, the contemporary of Darwin who independently deduced natural selection, German scientist and artist Ernst Haeckel (1834-1919) has fallen into relative obscurity. But Haeckel, a free-thinking supporter of evolution, was nevertheless a very popular figure of his time, as well as a keen and patient observer of nature. Influenced by Darwin's theories and contemporary German idealism, Haeckel offered his own variation on evolutionary theory: the belief that individual organisms "recapitulated," or replicated, every evolutionary development of the species.

After studying invertebrates for nearly six years, Haeckel became convinced that as organisms evolved, they became increasingly complex, a fact that was reflected in their tissues, if not in their outward appearance. From his close anatomical study of microscopic radiolarians, Haeckel deduced that all living things--from single-celled organisms to humans--exhibited symmetrical structures, and that symmetry was nature's most fundamental principle of unity, a "formula" for all organic life. He believed that as an organism evolved, its body would demonstrate richer symmetrical patterns.

Haeckel's belief that organisms became increasingly complex led him to pose the "Biogenetic Law," the theory that an individual organism's development (ontogeny) corresponded directly with the development of the species (phylogeny). For example, metazoans go through a developmental stage called a gastrula, a ball of cells with an infolding that later forms the gut. Haeckel thought that at one time an organism called a "gastraea" existed that looked much like the gastrula stage of a metazoan's development. Haeckel thought this hypothetical ancestral metazoan gave rise to the rest of the multi-celled animals. For some animals, Haeckel thought the _expression of earlier evolutionary stages was subtler, but he insisted that every organism contained a record of all the adaptations accumulated through its evolutionary history, whether visible or not. All living things, Haeckel believed, could be traced back to a single, simple primordial form.

While Haeckel's ideas generally have been discarded, he left a valuable legacy of written and illustrated material, including beautiful, detailed drawings of invertebrate anatomy collected in the book Art Forms in Nature. Haeckel's plates are imaginatively arranged to emphasize the rich symmetrical patterns he perceived as nature's unifying principle, and to stress the physical beauty he saw in nature's design.

British naturalist and explorer Alfred Russel Wallace independently invented the theory of evolution by natural selection in 1858, nearly scooping Charles Darwin, who published first. Nevertheless, Wallace's research led him to another important discovery, one that geologists still enshrine on their maps: Wallace's Line.

While exploring the vast 2,500-mile Malay Archipelago, Wallace noticed what kinds of animals lived on each island as he traveled farther from the mainland peninsula. He found that he could draw a boundary down the narrow Macasser Straight, which runs a twisted course between the islands of Bali and Lombock, and between Borneo and the Celebes group. Wallace's Line--an ocean channel only 15 miles wide--separates tigers from marsupials and trogons from cockatoos. The animals on either side of it, he wrote in 1858, "differ as much as those of South America and Africa. Yet there is nothing on the map to mark their limits. I believe the western part to be a separated portion of continental Asia, the eastern the fragmentary prolongation of a former Pacific continent."

Wallace had no way to observe the sea floor directly, and in his day nothing was known of tectonic plates. On the basis of animal distribution alone he deduced that the eastern island groups must have been separated from the western for much longer than any individual islands were separated from each other.

A hundred years later, geologists and oceanographers found the reason and the proof: Wallace's Line traverses an area of intense crustal activity, where the northward-moving Australian plate interacts with the western-moving Pacific (Asian-derived) plate. In addition to bringing two different geographic clusters of animals and plants close together, the plates' enormous pressures on each other and on the Eurasian continent has given rise to the most concentrated volcanic activity on Earth.

A popular legend states that Louis Daguerre, a French painter experimenting with photography in the mid-1830s, discovered how to develop images by accident. After placing some useless asphalt-and-oil plates in his chemical closet, he was surprised to find them developed upon his return. He removed the chemicals from the closet until he spotted a misplaced bowl of mercury on the floor. Additional experiments proved mercury vapor could develop an image on a metal plate and the daguerreotype was born.

The first daguerreotypes depended on a highly polished copper plate covered with silver powder that was "primed" by exposure to iodine, bromine, and a few other chemicals. When exposed to light for a few seconds, the primed surface etched the silver into the plate. Mercury vapor could then be used to darken the silver, resolving an image.

Daguerre based many of his experiments on his collaboration with French chemist Joseph Niepce, who found that a certain type of asphalt-lavender oil solution would react with a metal plate when exposed to light. Niepce used this method to create the first known photographic still in 1827. After Niepce's death in 1833, Daguerre worked on their research for six more years, and in 1839, he published his technique without copyright as a gift "from France to the rest of the world." The French government provided Daguerre with a pension for his gift and within months, a craze for photography called daguerreotypomania swept France and the United States.

Free access to Daguerre's process preserved the daguerreotype's popularity into the 1860s even though William Fox Talbot developed a much cheaper and easier paper-based photographic process called a Carlotype just two years after Daguerre's initial success. Unlike Daguerre, Fox patented his invention and few people were willing to pay for rights to the process when Daguerre's method was freely available.

From his earliest years, Marvin Minsky, "the father of Artificial Intelligence," loved to build machines. Frustrated by the limits of his toys, the young engineer began dismantling his father's optical equipment until the eye surgeon was forced to buy his son a truckload of junkyard parts. But Minsky's talent for tinkering and his brief exposure to medical machinery helped shape his lifelong ambition: to create a device capable of thought.

While a graduate student at Princeton in 1951, Minsky built the first primitive neural network learning machine from surplus World War II army equipment, including 400 vacuum tubes and 40 magnetic clutches. Unlike traditional computers, which must follow a specific order of programmed instructions to complete a task, Minsky's machine was designed to attempt several approaches to solving a problem. When the network performed certain tasks successfully, the instructions for that task were stored so that they could be instantly recalled, teaching the network to recognize patterns of effective behavior. In effect, the machine was teaching itself. Minsky's network was "smart" enough to simulate a rat learning its way through a maze.

Minsky's neural network laid the foundation for much of the later work done on neural nets, including his own more advanced research in 1969 based on more powerful learning algorithms called perceptrons. Today, neural networks used in fraud detection, credit approval, and target marketing have origins in Minsky's pioneering work.

Long affiliated with the Massachusetts Institute of Technology, where he is now a professor, Minsky has watched his machines advance fields as diverse as robotics, computerized vision, speech recognition, and parallel processing. While he still hasn't achieved his most elusive goal--a machine that thinks like a human, computers and other devices are closer to human reasoning than ever, thanks to Minsky's efforts.

In the spring of 1990, a few weeks after the Hubble Space Telescope was placed into Earth's orbit by the space shuttle Discovery, the US National Aeronautics and Space Administration (NASA) discovered that its $2.2-billion "eye above the sky" was partially blind. Images of deep-space objects and events relayed back to the control room at the Kennedy Space Center in Florida were blurry. The shape of the telescope's 8-foot-wide primary mirror was off by only 1/25th the width of a human hair--but enough to produce fuzzy images.

Scientists had such high hopes for Hubble's deep-space picture-taking ability. NASA had named its orbital telescope after American astronomer Edwin Hubble, who in the 1920s discovered galaxies far beyond the Milky Way--and that these "external galaxies" were in fact retreating from the Milky Way. The universe, he found, was expanding.

To study this and other phenomena better--without atmospheric interference--NASA built a 24,500-pound, school-bus-sized satellite containing a 7.8-foot-long reflecting telescope. Two thin panels of solar cells flank the telescope, and convert sunlight into electric power. In an average orbit, the telescope uses about the same amount of energy as 24 household light bulbs.

Multiple mirrors gather light from outer space objects and direct it into two cameras and two spectrographs (devices that record spectrums of light). A wide-field planetary camera can take pictures with image resolutions 10 times sharper than the biggest Earth-based telescope.

After figuring out how to fix the mirror, NASA dispatched a repair team in 1993 aboard the space shuttle Endeavour. Since being fixed, Hubble has answered many questions of the cosmos, such as the existence of black holes. Plans for a major upgrade in the telescope's camera in 2001 have raised scientists' hopes anew for even greater space discoveries.

When Sotheby's of London sold a large collection of Isaac Newton's (1642-1727) notebooks to economist John Maynard Keynes in 1936, the writings were deemed to have no scientific value. In 1942, after studying the papers, Keynes issued an incredulous report. "Newton was not the first of the Age of Reason," he said. "He was the last of the magicians." Keynes had bought Newton's writings on alchemy--theories and experiments that focus on changing substances into gold.

Alchemy was Newton's consuming passion for about two decades. He wrote more than a million words on the subject--far more than he ever wrote about physics. He also corresponded regularly on alchemy with Robert Boyle, another scientific giant of the 17th century who is now considered the father of modern chemistry.

Newton and Boyle both sought "the philosopher's stone," a mythical substance that could transform any material into gold. Like most alchemists, they also conspired to guard their principles and discoveries carefully, fearing "immense damage to the world" if alchemic secrets and methods fell into the wrong hands. After Boyle's death in 1691, for instance, Newton scrambled frantically to secure his mentor's secret recipes, then spent days recreating Boyle's attempts to turn mercury into gold. The experiments never bore fruit and may have caused Newton to suffer a mental breakdown brought about by mercury poisoning.

It is unfair to dismiss Newton's alchemy as "unscientific," because alchemy was considered serious science in the 17th century and made legitimate contributions to modern science. Alchemists identified many chemical elements, for instance, and developed methods and standards that shaped modern chemistry. And it turns out that alchemy isn't entirely pseudo-science. Radioactive decay naturally transforms potassium into argon all the time, and, as far-fetched as it sounds, scientists could change substances into gold--or anything else, for that matter--if they could find a way to manipulate the number of protons and neutrons in atomic nuclei.

Although it is still known as "Charles Darwin's theory," the Victorian naturalist might have trouble recognizing the current version of evolutionary theory. When first presented to the public in 1859, Darwin's theory--that species of living things are not fixed, but are changing constantly--was a puzzle with missing pieces. Darwin couldn't explain how evolution actually occurred; only offer evidence that it did. It would take decades of genetic research to fill in the gaps and refine his original conclusions.

Genetics was not understood in Darwin's day. He thought features acquired in an individual's lifetime could be passed on to offspring. Thirty years after Darwin's death, Mendelian genetics demonstrated that only genetic changes could be inherited. In the 1920s, mathematicians discovered evolution could be viewed as changes of gene frequencies in a population. Rather than continuing to focus on individuals as the units of evolution--with one "type" transforming into another--biologists began to think in terms of whole populations.

Darwin thought species were changing slowly all the time. Yet he couldn't explain why fossils of some creatures showed no change over long periods, only to be abruptly succeeded by different kinds of animals. He thought that perhaps this jumpy pattern was caused by imperfections in the fossil record, "as if one were trying to read a book that was missing many pages, and even whole chapters."

According to the theory of punctuated equilibrium advanced in the 1970s, however, these apparent "leaps" are how evolution proceeds. Species remain stable and relatively unchanged for long periods of time and then, pushed by climatic or environmental changes, undergo periods of comparatively rapid evolution. Although the details of evolutionary theory have changed greatly since Darwin's day, his basic idea continues to be the underpinning of all the life sciences. That, at least, has not yet changed.