Expanding Universe

Year of Discovery: 1926

What Is It? The universe is expanding. The millions of galaxies move ever outward, away from its center.

Who Discovered It? Edwin Hubble

Why Is This One of the 100 Greatest?

Hubble’s twin discoveries (that there are many galaxies in the universe—not just the Milky Way—and that all of those galaxies are traveling outward, expanding the universe) rank as the most important astronomical discoveries of the twentieth century. These discoveries radically changed science’s view of the cosmos and of our place in it. Hubble’s work also represents the first ac cu rate assessment of the movement of stars and galaxies.

The discovery that the universe is expanding and ever changing for the first time allowed scientists to ponder the universe’s past. This discovery led directly to the discovery of the Big Bang and the origin of the universe as well as to a new concept of time and of the future of the universe.

How Was It Discovered?

In 1923 Edwin Hubble was a tall, broad-shouldered, powerful astronomer of 33 who, 10 years earlier, had almost chosen a career as a professional boxer over astronomy. Hubble had been hired in 1920 to complete and operate the Mt. Wilson Observatory’s mammoth 100-inch telescope in California—the largest telescope in the world.

In the early twentieth century, the universe was thought to contain one galaxy—the Milky Way—plus scattered stars and nebulae drifting around its edges. Hubble decided to use the giant 100-inch telescope to study several of these nebulae and picked Andromeda as his first target—and he made the two most important astronomical discoveries of the twentieth century.

This giant telescope’s power showed Hubble that Andromeda wasn’t a cloud of gas (as had been thought). It was a dense cluster of millions of separate stars! It looked more like a separate galaxy.

Then Hubble located several Cepheid stars in Andromeda. Cepheid stars pulse. The beat of their pulse is always a direct measure of the absolute amount of light given off by the star. By measuring their pulse rate and their apparent amount of light, scientists can determine the exact distance to the star.

Andromeda lay 900,000 light-years away. That proved that Andromeda was a separate galaxy. It lay too far away to be a fringe part of the Milky Way.

Within six months, Hubble had studied and measured 18 other nebulae. They were all separate galaxies, ranging from five to 100 million light-years from Earth. Astronomers were shocked to learn that the universe was so big and that it likely contained thousands of separate galaxies.

But Hubble was just beginning. He had noticed a consistent red shift when studying the light emitted from these distant nebulae.

Scientists had discovered that each element (helium, hydrogen, argon, oxygen, etc.) always emit ted energy in a character is tic set of specific frequencies that identified the element’s presence. If they made a spec tro graph (a chart of the energy radiated at each separate frequency) of the light being emitted from a star, the lines on the spectrograph would tell them which elements were present in the star and in what relative quantities.

Hubble found all the common spectrograph lines for helium, hydrogen, and so forth that were normally found in a star. But all the lines on his graph were at slightly lower frequencies than normal. It was called a red shift be cause when visible light frequencies are lowered, their color shifts toward red. If their frequency is raised, their color shifts toward blue (a blue shift).

Over the next two years, Edwin Hubble conducted exhaustive tests of the 20 galaxies he had identified. He found that every one (except Andromeda) was moving away from Earth. More startling, the galaxies moved away from us and away from each other. Every galaxy he studied was speeding straight out into open space at speeds of between 800 and 50,000 kilometers per second!

The universe was expanding, growing larger every second as the galaxies raced out-ward. It was not a static thing that had remained unchanged since the beginning of time. In each moment the universe is different than it has ever been before.

Fun Facts: Because the universe is expanding, every galaxy in existence is moving away from our own Milky Way—except for one. Andromeda, our nearest neighbor, is moving on a collision course with the Milky Way. Don’t worry, though: the collision won’t occur for several million years.

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Quantum Theory

Year of Discovery: 1925

What Is It? A mathematical system that accurately describes the behavior of the subatomic world.

Who Discovered It? Max Born

Why Is This One of the 100 Greatest?

In the first 20 years of the twentieth century, physics buzzed with the incredible discovery of the subatomic world. Long before microscopes were powerful enough to allow researchers to see an atom, scientists used mathematics to probe into the subatomic world of electrons, protons, and alpha and beta particles.

Albert Einstein, Werner Heisenberg, Max Planck, Paul Dirac, and other famed researchers posed theories to explain this bizarre new territory. But it was quiet, unassuming Max Born who discovered a unified quantum theory that systematically, mathematically described the subatomic world.

Max Born’s gift to the world was a brand-new field of study we call “quantum mechanics” that is the basis of all modern atomic and nuclear physics and solid state mechanics. It is because of Max Born that we are now able to quantitatively describe the world of subatomic particles.

How Was It Discovered?

Einstein published his general theory of relativity in 1905. So, for the last year and a half of his university study, 25-year-old Göttingen University mathematics student Max Born lived in a world abuzz with the wonder, implications, and potential of Einstein’s bold and revolutionary theory.

Bitterly frustrated that he couldn’t find a post graduate position that would allow him to continue his studies of the subatomic world, Born returned home to live in his childhood room. Working alone for two years at the desk he used for homework as a boy, he tried to apply his mathematical teachings to the problems of subatomic relativity as described in Einstein’s theory. Through this work, Max Born discovered a simplified and more accurate method of calculating the minuscule mass of an electron.

Born wrote a paper on his findings that generated an offer for a full-time position at Göttingen University. Two weeks after he started, the job evaporated. Born limped back home for another full year of independent study and a second paper, a review of the mathematical implications of Einstein’s relativity, before he was offered a lecturing position at Göttingen University.

However, the only available research funding was designated for the study of the vibrational energy in crystals. Deeply disappointed, feeling excluded from the grand hunt for the structure of the atom, Born launched his study of crystals. For five years Born and two assistants collected, grew, sliced into paper-thin wedges, studied, measured, and analyzed crystals.

In 1915 Born shifted to the University of Berlin to work with physics giant Max Planck. Planck and Einstein were at the hub of the race to unravel and understand the sub - atomic world. Born brought his mathematical superiority and his understanding of crystals to aid their efforts. It was a classic case of finally be ing in the right place at the right time with the right background.

Theories abounded to explain the peculiar behavior of subatomic particles. But no one was able to write down the mathematics that proved and described those theories. The problem had mystified the greatest minds in the scientific world for almost 20 years.It occurred to Born that the quantum phenomena physicists found so troubling in electrons looked remarkably similar to the behavior of the crystals he had studied for five years.

In 1916 Born started to apply what he had learned with crystals to the immense and complex numerical problem that surrounded subatomic particles. The work stretched the available mathematical tools to their limits. The effort extended over nine years of work on blackboards, on note pads, and with slide rules.

In 1925 Born completed work on “Zur Quantenmechanik,” or “On Quantum Mechanics.” The phrase had never been used before. The paper exploded across the scientific world. It clearly, mathematically, laid out the fundamentals that Einstein, Planck, Dirac, Niels Bohr, Hermann Minkowski, Heisenberg, and others had talked about. It concretely explained and described the amazing world of subatomic particles.

“Quantum mechanics” became the name of the new field of study that focused on a quantitative description of subatomic phenomena. Max Born became its founder.

Fun Facts: In the bizarre quantum world, many of our “normal” laws do not apply. There, objects (like electrons) can be (and regularly are) in two different places at once without upsetting any of the laws of quantum existence.

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Human Evolution

Year of Discovery: 1924

What Is It? Humanoids evolved first in Africa and, as Darwin had postulated, developed from the family of apes.

Who Discovered It? Raymond Dart

Why Is This One of the 100 Greatest?

Humans have always wondered how we came to be on this planet. Virtually every culture and religion has created myths to explain the creation of humans. In the early twentieth century, most scientists believed that the first humans appeared in Asia or Eastern Europe. Then Dart discovered the Taung skull and provided the first solid evidence both of an African evolution of the first humanoids and a fossil link between humans and apes, substantiating one part of Darwin’s theories. This discovery redirected all of human evolutionary research and theory and has served as a cornerstone of science’s mod ern beliefs about the history and origin of our species.

How Was It Discovered?

Raymond Dart was born in Queensland, Australia, in 1893 on a bush farm where his family was struggling to raise cattle. He excelled in school and received scholarships to study medicine, specializing in neural anatomy (the anatomy of skull and brain). In 1920 he gained a prestigious position as assistant to Grafton Elliot Smith at the University of Manchester, England. But their relationship soured and, in 1922, shortly after his thirtieth birthday, Dart was sent off to be a professor of anatomy at the newly formed University of Witwatersrand in Johannesburg, South Africa. Dart arrived feeling bitterly betrayed and outcast.

In 1924 Dart learned of several fossil baboon skulls that had been found at a nearby limestone quarry at Taung. Dart asked that they be sent to him along with any other fossils found at the site. He did not an ticipate finding anything particularly interesting in these fossils, but the new university’s anatomical museum desperately needed anything it could get.

The first two boxes of fossil bones were delivered to Dart’s house one Saturday after-noon in early September 1924, just as he was dressing for a wedding reception to be held at his house later that afternoon. He almost set the boxes aside. But curiosity made him open them there in his driveway. The first box contained nothing of particular interest.

However, on top of the heap of rock inside the second box lay what he instantly recognized as undoubtedly a cast or mold of the interior of a skull—a fossilized brain (rare enough in and of itself). Dart knew at first glance that this was no ordinary anthropoid (ape) brain. It was three times the size of a baboon’s brain and considerably larger than even an adult chimpanzee’s.The brain’s shape was also different from that of any ape Dart had studied. The forebrain had grown large and bulging, completely covering the hind brain. It was closer to a human brain and yet, certainly, not fully human. It had to be a link between ape and human.

Dart feverishly searched through the box for a skull to match this brain so that he could put a face on this creature. Luckily he found a large stone with a depression into which the brain cast fit perfectly. He stood transfixed in the driveway with the brain cast and skull-containing rock in his hands, so long that he was late for the wedding.He spent the next three months patiently chipping away the rock matrix that covered the actual skull, using his wife’s sharpened knitting needles. Two days before Christmas, a child’s face emerged, complete with a full set of milk teeth and permanent molars still in the process of erupting. The Taung skull and brain were that of an early human like child.

Dart quickly wrote an article for Nature magazine describing his discovery of the early humanoid and showed how the structure of the skull and spinal cord connection clearly showed that the child had walked upright. Dart claimed to have discovered the “missing link” that showed how humans evolved in the African plain from apes.

The scientific community were neither impressed with Dart’s description nor convinced. All European scientists remained skeptical until well-respected Scotsman Robert Broom dis-covered a second African skull in 1938 that supported and substantiated Dart’s discovery.

Fun Facts: Darwin believed that humanoids emerged in Africa. No one believed him for 50 years, until Dart uncovered his famed skull in 1924.

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Neurotransmitters

Year of Discovery: 1921

What Is It? Chem i cal substances that transmit nerve im pulses be tween individual neuron fibers.

Who Discovered It? Otto Loewi

Why Is This One of the 100 Greatest?

Like cracking the genetic code, like the creation of the atomic bomb, the discovery of how the brain’s system of neurons communicates is one of the fundamental science developments of the twentieth century.

Nerves signal sensations to the brain; the brain flashes back commands to muscles and organs through nerves. But how? Otto Loewi’s discovery of neurotransmitters (the chemicals that make this communication possible) revolutionized the way scientists think about the brain and even what it means to be human. Neurotransmitters control memory, learning, thinking, behavior, sleep, movement, and all sensory functions. This discovery was one of the keys to understanding brain function and brain organization.

How Was It Discovered?

In 1888 German anatomist Heinrich Walder-Hartz was the first to propose that the nervous system was a separate network of cells. He named these nerve fibers neurons. He concluded that the ends of individual nerve cells approached each other closely, but didn’t actually touch. In 1893 Italian scientist Camillo Colgi used a new method for staining cells that brought out exceptionally fine detail under a microscope and proved that Walder-Hartz was correct.

Walder-Hartz’s discovery, however, created a scientific controversy. If neurons didn’t actually touch, how did they communicate? Some scientists argued that signals had to be sent electrically, since electrical currents existed in the brain. Some argued that nerve signals had to be sent chemically since there were no solid electrical connections be tween individual neurons. Neither side could prove its position.Otto Loewi was born in Frankfurt, Germany, in 1873. 

He wanted to become an art historian but buckled under family pressure and agreed to attend medical school. After barely passing his medical examination, Loewi worked in the City Hospital in Frankfurt. However, he became depressed by the countless deaths and great suffering of tuberculosis and pneumonia patients left to die in crowded hospital wards because there was no therapy for them. 

Loewi quit medical practice and turned to pharmacological research (the study of drugs and their effects on human organs). Over the next 25 years (1895 to 1920) he studied how different human organs responded to electrical and chemical stimuli. His papers reported on many human organs including the kidney, pancreas, liver, and brain.

By 1920 Loewi was focusing much of his attention on nerves. He was convinced that chemicals carried signals from one nerve fiber to the next. But, like other researchers, he couldn’t prove it.

Loewi later said that the an swer came to him in a dream. It was the night be fore Easter Sunday, 1921. Loewi woke up with a start around midnight and scribbled notes about the dream’s idea. The next morning he was unable to read his scrawled notes. Nor could he remember what the dream had been about. All he could remember was that the notes and the dream were critical.

The next night he awoke at 3:00 A.M. from the same dream, remembering it clearly. He didn’t dare go back to sleep. He rose and drove to his lab, where he performed the simple experiment from his dream—an experiment that has become famous.

Loewi surgically removed the still-beating hearts from two frogs and placed each in its own container of saline (salt) solution. He left the autonomic nerve (the Vagus nerve) attached to heart number one, but not to the second heart. When he applied a tiny electrical current to heart number 1’s Vagus nerve, the heart slowed down. When he then allowed some saline solution from container 1 to flow into container 2, the second heart slowed down to match the slower rate of the first heart.

Electricity could not have affected the second heart. It had to be some chemical released into the saline solution by heart 1’s Vagus nerve that then communicated with and controlled heart 2. Loewi had proved that nerve cells communicate with chemicals. Loewi called this chemical vagusstoff. 

A friend of Loewi’s, Englishman Henry Dale, was the first to isolate and decode this chemical’s structure, which we now call acetylcholine. Dale coined the name neurotransmitters for this group of chemicals that nerves use for communication.

Fun Facts: The longest nerve cell in your body, the sciatic nerve, runs from your lower spine to your foot, roughly two to three feet in length!

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Insulin

Year of Discovery: 1921

What Is It? Insulin is a hormone produced by the pancreas that allows the body to pull sugar from blood and burn it to produce energy.

Who Discovered It? Frederick Banting

Why Is This One of the 100 Greatest?

Frederick Banting discovered a way to re move and use the pancreatic “juice” of animals to save the lives of diabetic humans. This hormone is called insulin. Its discovery has saved millions of human lives. Diabetes used to be a death sentence. There was no known way to replace the function of a pancreas that had stopped producing insulin. Banting’s discovery changed all that.

Although insulin is not a cure for diabetes, this discovery turned the death sentence of diabetes into a manageable malady with which millions of people live healthy and normal lives.

How Was It Discovered?

In early 1921, 28-year-old Canadian orthopedic surgeon Frederick Banting developed a theory—actually, it was more of a vague idea—for a way to help people suffering from diabetes.

The outer cells of the pancreas produced strong digestive juices. But the inner cells produced a delicate hormone that flowed straight into the blood. Muscles got their energy from sugars in the bloodstream, which came from food. But the body couldn’t pull sugar out of the bloodstream without that hormone from the inner cells of the pancreas.

When the inner cells of a person’s pancreas stopped making that hormone, their muscles couldn’t draw sugar from the bloodstream, and the bloodstream became overloaded with sugar and struggled to get rid of it through excess urination. The body dehydrated; and the patient became deathly ill. This condition was called diabetes.

In 1920 there was no cure for diabetes. It was always fatal.Researchers had tried obtaining the pancreatic hormone (which they referred to as “juice”) from animals. But when a pancreas was ground up, the digestive juices from the outer cells were so strong that they destroyed the delicate juice from the inner cells before it could be used.

Banting read an article by Dr. Moses Barron that described the fate of several patients in whom a block age had developed in the ducts carrying pancreatic outer cell digestive juices to the stomach. These strong acids had been trapped in the outer cells of the pancreas and had destroyed those cells. The cells literally shut down and dried up.

Banting wondered if he could intentionally kill the outer pancreatic cells of an animal and then harvest its inner cell juice for use by diabetic humans.

His plan was simple enough. Operate to tie off the ducts from a dog’s pancreatic outer cells to the stomach, wait the eight weeks Dr. Barron had mentioned in his article, and hope that the outer cells had dried up and died. Finally, in a second operation, he would harvest the dog’s pancreas and see if it still contained life-giving inner cells and their precious juice. He would artificially create diabetes in another dog s and see if the pancreatic fluid from the first dog could keep it alive.

With no funding, Banting talked his way into the use of a lab and six test dogs. The surgery was simple enough. Now he had to wait eight weeks for the outer cells to die.

However, early in week six the diabetic dog slid into a coma. This was the last stage before death. Banting couldn’t wait any longer. He operated on one of the other dogs, successfully removing its pancreas. He ground up this tissue and extracted the juice by dissolving it in a chloride solution.

He injected a small amount of this juice into the diabetic dog. Within 30 minutes the dog awakened from its coma. Within two hours it was back on its feet. In five hours it began to slide back down hill. With another injection it perked up, with enough energy to bark and wag its tail.Banting was ecstatic. His hunch had been right!

Dr. John Marcum named the juice, “insulin” during the two years that he and Dr. Banting searched for a way to create this precious juice without harming lab dogs—a feat they eventually accomplished.

Fun Facts: In 1922 a 14-year-old boy suffering from type I diabetes was the first person to be treated with insulin. He showed rapid improvement.

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