Sports and life by the sports kibitzer : this blog was created for the love of sports and life...and all that matters most! Photo from 2014 Fathers' Day dinner with family in Boracay...
In 2007, the United States
spent $368 billion on research and development, according to the
National Science Foundation. Nearly 18 percent of that enormous pie went
to fund basic research -- the kind driven by a scientist's curiosity or
interest in a scientific question. Another 22 percent went to applied
research -- research designed to solve practical problems [source: Boroush].
With so many scientists conducting so
many experiments every year both in and out of the lab, it's not
surprising that most investigations enjoy little acclaim. Every so
often, though, an experiment captures the attention of scientists and
laypeople alike, either because it alters our fundamental understanding
of the natural world or because it reveals a solution that addresses a
serious public health concern. You might think that such revelatory
experiments are extraordinarily complex, and you would be right about
some. But just as many are stellar examples of grace and simplicity.
In this article, we'll consider 10 of
the most sublime experiments, in our humble opinion. They're organized
according to the major disciplines of science -- biology, chemistry,
physics and psychology -- and span more than 200 years of inquiry. In a
few cases, we've paired two closely related experiments together in a
single spot, not to hedge our bets, but to prove that science is a
collaborative endeavor.
The first of our 10 science experiments is Charles Darwin and his orchids.
Most people are familiar with Charles Darwin's activities aboard the HMS Beagle and its famous journey to South America. He made some of his most important observations on the Galapagos Islands,
where each of the 20 or so islands supported a single subspecies of
finch perfectly adapted to feed in its unique environment. But few
people know much about Darwin's experiments after he returned to England. Some of them focused on orchids.
As Darwin grew and studied several
native orchid species, he realized that the intricate orchid shapes
were adaptations that allowed the flowers to attract insects that would
then carry pollen to nearby flowers. Each insect was perfectly shaped
and designed to pollinate a single type of orchid, much like the beaks
of the Galapagos finches were shaped to fill a particular niche. Take
the Star of Bethlehem orchid (Angraecum sesquipedale), which
stores nectar at the bottom of a tube up to 12 inches (30 centimeters)
long. Darwin saw this design and predicted that a "matching" animal
existed. Sure enough, in 1903, scientists discovered that the hawk moth
sported a long proboscis, or nose, uniquely suited to reach the bottom
of the orchid's nectar tube.
Darwin used the data he collected
about orchids and their insect pollinators to reinforce his theory of
natural selection. He argued that cross-pollination produced orchids
more fit to survive than orchids produced by self-pollination, a form of
inbreeding that reduces genetic diversity and, ultimately,
survivability of a species. And so three years after he first described
natural selection in "On the Origin of Species," Darwin bolstered the
modern framework of evolution with a few flower experiments.
Image Credit: Life Pictures/Mansell/Time Life Pictures/Getty Images
9: Decoding DNA
James Watson and Francis Crick get the credit for unlocking the mystery of DNA,
but their discovery depended heavily on the work of others, like Alfred
Hershey and Martha Chase, who, in 1952, conducted a now-famous
experiment that identified DNA as the molecule responsible for heredity.
Hershey and Chase worked with a type of virus known as a bacteriophage. Such a virus, made up of a protein coat surrounding a strand of DNA, infects a bacteria cell,
programs the cell to make more viruses, then kills the cell to release
the newly made viruses. The two knew this, but they didn't know which
component -- protein or DNA -- was responsible until their ingenious
"blender" experiment directed them to DNA's nucleic acids.
After Hershey and Chase's
experiment, scientists like Rosalind Franklin focused on DNA and rushed
to decipher its molecular structure. Franklin used a technique called X-ray diffraction to study DNA. It involves shooting X-rays
at aligned fibers of purified DNA. As the X-rays interact with the
molecule, they are diffracted, or bent, off their original course. When
allowed to strike a photographic plate, the diffracted X-rays form a
pattern that's unique to the molecule being analyzed. Franklin's famous
photo of DNA shows an X-shaped pattern that Watson and Crick knew was a
signature of a helical (or spiral-shaped) molecule. They could also
determine the width of the helix from looking at Franklin's image. The
width suggested that two strands made up the molecule, leading to the
double-helix shape we all take for granted today.
Until the stunning global
eradication of smallpox in the late 20th century, smallpox posed a
serious health problem. In the 18th century, the disease caused by the
variola virus killed every tenth child born in Sweden and France [source: World Health Organization].
Catching smallpox and surviving the infection was the only known
"cure." This led many people to inoculate themselves with fluid and pus
from smallpox sores in the hopes of catching a mild case. Unfortunately,
many people died from their dangerous self-inoculation attempts.
Edward Jenner, a British physician,
set out to study smallpox and to develop a viable treatment. The genesis
of his experiments was an observation that dairymaids living in his
hometown often became infected with cowpox, a nonlethal disease similar
to smallpox. Dairymaids who caught cowpox seemed to be protected from
smallpox infection, so in 1796, Jenner decided to see if he could confer
immunity to smallpox by infecting someone with cowpox on purpose. That
someone was a young boy by the name of James Phipps. Jenner made cuts on
Phipps' arms and then inserted some fluid from the cowpox sores of a
local dairymaid named Sarah Nelmes. Phipps subsequently contracted
cowpox and recovered. Forty-eight days later, Jenner exposed the boy to
smallpox, only to find that the boy was immune.
Today, scientists know that cowpox
viruses and smallpox viruses are so similar that the body's immune
system can't distinguish them. In other words, the antibodies made to
fight cowpox viruses will attack and kill smallpox viruses as if they
were the same.
Physicist Ernest Rutherford had already won a Nobel Prize in 1908 for his radioactivity work when he began some experiments that would reveal the structure of the atom.
They relied on his previous research showing that radioactivity
consisted of two types of rays -- alpha and beta rays. Rutherford and
Hans Geiger had determined that alpha rays were streams of positively
charged particles. When he fired alpha particles at a screen, they
created a sharp, crisp image. But if he placed a thin sheet of mica
between the alpha-ray source and the screen, the resulting image was
diffuse. Clearly, the mica was scattering some alpha particles, but how
and why?
In 1911, he positioned a thin sheet
of gold foil, just one or two atoms thick, between the alpha-ray source
and the screen. He placed a second screen by the alpha-ray source to see
if any particles were being deflected straight back. On the screen
behind the foil, Rutherford observed a diffuse pattern similar to the
one he saw with the mica. On the screen in front of the foil, Rutherford
was astonished to see that a few alpha particles bounced straight back. Rutherford concluded that a strong
positive charge at the heart of the gold atoms was deflecting the alpha
particles straight back toward the source. He called this strong
positive source the "nucleus," and said the nucleus must be small
compared to the atom's overall size; otherwise, more particles would
have bounced back. Today, we still visualize the atom as Rutherford did:
a small, positively charged nucleus surrounded by a vast, mostly empty
region with a few electrons.
Image Credit: Creativ Studio Heinemann/Getty Images
6: X-ray Vision
We spoke of Rosalind Franklin's
X-ray diffraction studies earlier, but her work owed much to Dorothy
Crowfoot Hodgkin, one of only three women ever to win the Nobel Prize in chemistry. In 1945, Hodgkin was considered the world's foremost practitioner of X-ray
diffraction techniques, so it's not surprising that she eventually
revealed the structure of one of medicine's most important chemicals --
penicillin. Alexander Fleming had discovered the bacteria-killing
substance in 1928, but scientists struggled to purify the chemical in
order to develop an effective treatment. By mapping out the 3-D
arrangement of penicillin's atoms,
Hodgkin opened new avenues for creating and developing semisynthetic
derivatives of penicillin, revolutionizing how doctors fought
infections.
Hodgkin's field of study was known as X-ray crystallography.
Chemists first had to crystallize the compounds they wanted to analyze,
which was a challenge. After two different companies sent her
penicillin crystals, Hodgkin then passed X-ray waves through the
crystals and allowed the radiation to strike a photographic plate. As
the X-rays interacted with electrons in the sample, they were diffracted
slightly. This resulted in a distinct pattern of spots on the
photographic film. By analyzing the position and brightness of these
spots and performing numerous calculations, Hodgkin determined exactly
how the atoms in the penicillin molecule were arranged.
A few years later, Hodgkin used the
same technique to solve the structure of vitamin B12. She won the Nobel
Prize in chemistry unshared in 1964 -- an honor that no other woman has
duplicated.
Go back far enough in time, and you
eventually have to explain how the chemicals of life -- especially
proteins and nucleic acids -- formed in Earth's primordial environment.
In 1929, biochemists John Haldane and
Aleksander Oparin hypothesized independently that Earth's early
atmosphere lacked free oxygen. In this harsh environment, they
suggested, organic compounds could form from simple molecules if they
were stimulated by a strong source of energy, either ultraviolet
radiation or lightning. Haldane added that the oceans would have been a
"primitive soup" of these organic compounds.
U.S. chemists Harold C. Urey and
Stanley Miller set out to test the Oparin-Haldane hypothesis in 1953.
They reproduced the early atmosphere of Earth by creating a carefully
controlled, closed system. The ocean was a warmed flask of water.
As water vapor rose from the water and collected in another chamber,
Urey and Miller introduced hydrogen, methane and ammonia to simulate the
oxygen-free atmosphere. Then they discharged sparks, representing
lightning, into the mixture of gases. Finally, a condenser cooled the
gases into a liquid they collected for analysis.
After a week, Urey and Miller had
astonishing results: Organic compounds were abundant in the cooled
liquid. Most notably, Miller found several amino acids, including
glycine, alanine and glutamic acid. Amino acids are the building blocks
of proteins, which themselves are the key ingredients of both cellular
structures and cellular enzymes responsible for important chemical
reactions. Urey and Miller concluded that organic molecules could form
in an oxygen-free atmosphere and that the simplest of living things
might not be far behind.
Image Credit: George Karger/Pix Inc./Time Life Pictures/Getty Images
4: Making Light
When the 19th century dawned, light
remained a mystery that inspired several fascinating experiments, most
notably Thomas Young's "double-slit experiment" that told us light
behaved as a wave, not as a particle. But we still didn't know how fast
it traveled.
In 1878, physics instructor A.A.
Michelson devised an experiment to calculate the speed of light and
prove that it was a finite, measurable quantity. Here's what he did:
First, he placed two mirrors far
apart on a seawall near campus, aligning them so that light striking
one mirror would reflect back and strike the second. He measured the
distance between the two mirrors and found they were 1,986.23 feet
(605.4029 meters) apart.
Next, Michelson used a steam-powered blower to spin one of the mirrors at 256 revolutions per second. The other mirror remained stationary.
Using
a lens, he focused a beam of light onto the stationary mirror. When the
light struck the stationary mirror, it bounced back toward the rotating
mirror, where Michelson had placed an observation screen. Because the
second mirror was moving, the returning light beam was deflected
slightly.
When Michelson measured the deflection, he found it to be 5.236 inches (133 millimeters).
Using this data, Michelson calculated the speed of light to be 186,380 miles per second (299,949.53 kilometers per second).
The accepted value for the speed of
light today is 186,282.397 miles per second. Michelson's measurement was
amazingly accurate. More important, scientists had a more accurate
picture of light and a foundation upon which to build the theories of
quantum mechanics and relativity.
The year 1897 was momentous for Marie
Curie. Her first child with husband Pierre was born and, a few weeks
later, she went looking for a subject for a doctoral thesis. She
eventually decided to study the "uranium rays," first described by Henri
Becquerel. Becquerel had discovered these rays accidentally when he
left uranium salts in a dark room and returned to find that they had
exposed a photographic plate. Marie Curie chose to study these
mysterious rays and to determine if other elements gave off similar
emissions.
Early on, Curie learned that thorium
gave off the same rays as uranium. She started labeling these unique
elements as "radioactive" and quickly discovered that the strength of radiation
emitted by various uranium and thorium compounds didn't depend on the
compound, but on the amount of uranium and thorium present. Eventually,
she would prove that the rays were a property of the atoms of a radioactive element. By itself, this was a revolutionary discovery, but Curie wasn't done.
She found that pitchblende produced
more radioactivity than uranium, leading her to predict that an unknown
element must be present in the naturally occurring mineral. Pierre
joined her in the lab, and they systematically reduced great quantities
of pitchblende until they finally isolated the new element. They named
it polonium after Poland, Marie's homeland. Soon after, they discovered
another radioactive element, which they named radium after the Latin
word for "ray." Curie won two Nobel Prizes for her work.
Did you know that Ivan Pavlov, the Russian-born physiologist and chemist responsible for the salivating-dogs experiment, wasn't interested in psychology or behavior? The research topics that interested him most were digestion and blood circulation. In fact, he was studying canine digestion when he discovered what we know today as classical conditioning.
Specifically, he was trying to
understand the interaction between salivation and the action of the
stomach. Pavlov had already noted how the stomach wouldn't start
digesting without salivation occurring first. In other words, reflexes
in the autonomic nervous system closely linked the two processes. Next,
Pavlov wondered if external stimuli could affect digestion similarly. To
test this, he began flashing a light, ticking a metronome or sounding a
buzzer at the same time he offered food to his research dogs. In the
absence of these external stimuli, the dogs only salivated when they saw
and ate their food.
But after a while, they began to salivate when stimulated with external
lights or sounds, even when food wasn't present. Pavlov also found that
this type of conditioned reflex dies out if the stimulus proves "wrong"
too often. For example, if the buzzer sounds repeatedly and no food
appears, the dog eventually stops salivating at the sound.
Pavlov published his results in 1903.
A year later, he won a Nobel Prize in medicine, not for his work with
conditioning, but "in recognition of his work on the physiology of
digestion, through which knowledge on vital aspects of the subject has
been transformed and enlarged" [source: Nobelprize.org].
Stanley Milgram's 1960s obedience
experiments qualify as some of the most famous and controversial science
experiments. Milgram wanted to know how far ordinary people would go in
delivering painful shocks to a peer, when commanded to do so by a
scientific authority. This is his experiment:
Milgram recruited volunteers --
ordinary residents -- to deliver the shocks. He recruited actors to be
the subjects who would receive the shocks. The final player was the
authority figure, a scientist who would remain in the room for the
study's duration.
The authority figure began each experiment by
showing the unknowing volunteer how to use the mock shock machine. The
machine allowed volunteers to deliver up to 450 volts, a shock labeled as highly dangerous.
Next,
the scientist told the volunteers they were testing to see how shocks
might improve word association recall. He instructed the volunteers to
shock learners (actors) for wrong answers and to raise the voltage as
the experiment progressed.
The learners cried out whenever they
received a shock. At about 150 volts, they would demand to be freed. The
scientist encouraged volunteers to continue delivering shocks no matter
how agitated the learners became.
Some volunteers stopped at about 150 volts, but most kept going until they reached the maximum shock level of 450 volts.
Many people questioned the ethics of
the experiments, but the results were fascinating. Milgram showed that
average people will inflict a lot of pain on an undeserving victim
simply because an authority commands them to do so.
Keep reading for more links on science and great scientific thinkers.
American Museum of Natural
History. "Darwin, A Life's Work: Wonderful Creatures, These Orchids."
(Nov. 24, 2008)
http://www.amnh.org/exhibitions/darwin/work/orchids.php
Boroush,
Mark. "New Estimates of National Research and Development Expenditures
Show 5.8% Growth in 2007." National Science Foundation. August 2008.
(Nov. 24, 2008)
http://www.nsf.gov/statistics/infbrief/nsf08317/
Byrne, Seamus.
"Ironically named 'Star of Bethlehem' orchid supports Darwin's theory of
evolution." Gizmodo. Nov. 9, 2007. (Nov. 24, 2008)
http://www.gizmodo.com.au/2007/11/ironically_named_star_of_bethl.html
Campbell, Neil A. and Jane B. Reece. "Biology, Seventh Edition." Pearson Benjamin Cummings. 2005.
Carey,
Benedict. "Decades Later, Still Asking: Would I Pull That Switch?" New
York Times. July 1, 2008 (Nov. 24, 2008)
http://www.nytimes.com/2008/07/01/health/research/01mind.html
Davis, Audrey. "Jenner, Edward." World Book Multimedia Encyclopedia. 2004.
Farndon, John. "The Great Scientists." Metro Books. 2007.
Fröman,
Nanny. "Marie and Pierre Curie and the Discovery of Polonium and
Radium." Nobelprize.org. Dec. 1, 1996. (Nov. 24, 2008)
http://nobelprize.org/nobel_prizes/physics/articles/curie/index.html
Johnson,
George. "Here They Are, Science's 10 Most Beautiful Experiments." New
York Times. Sept. 24, 2002. (Nov. 24, 2008)
http://query.nytimes.com/gst/fullpage.html?res=9D06E6D91439F937
A1575AC0A9649C8B63
Johnson, George. "The Ten Most Beautiful Experiments." Alfred A. Knopf. 2008.
Image Credit: flashfilm/Getty Images
No comments:
Post a Comment