There are many different forms of pollution.. Driven by curiosity and desire to help humanity, scientists have made great progress in understanding nature.. Different interpretation of f
Trang 1Along with advances in technology came a different kind
of warfare—mass destruction and complete disregard
for the environment To end World War II and test a new
weapon, the United States dropped two atomic bombs
on Japan, instantly ending countless lives Chemical and
biological weapons, and cluster bombs containing
depleted uranium, present another danger All these
weapons affect not only the humans involved in wars
now, but future generations, and plant and animal life
Solar Power
Solar power refers to the conversion of solar energy to
another, more useful form Sunlight can be harnessed
and collected in special greenhouses Photosensitive cells
can produce electricity when sunlight hits them The sun
produces about ten times the energy fossil fuels create
each year Many scientists are convinced that this form of
energy will one day replace ordinary fossil fuels
Cur-rently, one reason that we still do not see solar-powered
cars and houses is because fossil fuels are cheaper to
col-lect and use But technology is slowly catching up—solar
plants are now being constructed in some parts of the
United States Scientists are hopeful that these new plants
will be able to produce enough energy to power our cities
in the future
Genetic Engineering
One of the fastest growing fields in science, and also
pos-sibly the most controversial, genetic engineering, has
been making headline news The first thing that comes to
mind is cloning But there is more to genetic engineering
than that Genetic engineering is used to produce
every-day products such as fruits, grains, plants, and even
ani-mals like fish This might be a bit pointless, you might
say Certainly, we have had fruits, plants, and animals
before Why do we have to genetically engineer these
products?
We do not make these products from scratch Genetic
engineering allows us to modify the product to bring out
certain qualities or to embed qualities that the product
would not normally have For example, Florida oranges
grow best in Florida because oranges prefer lots of sun
and warm temperatures Genetic engineering can
mod-ify the trees so that the oranges can grow in colder
cli-mates, like further north
While making an orange tree that can grow anywhere seems like a good idea, we must look at the flip side and examine other projects What effect would an orange tree
in Alaska have on other plant and animal life in Alaska?
In China, scientists concerned with overpopulation and hunger developed a strain of rice that will grow twice as fast as normal rice This means that more food can be produced faster Unfortunately, the faster-growing rice has half the nutrients of normal rice Is this a step up? Now there is more rice available for the population, but
it is less nutritious than natural rice
E n v i r o n m e n t a l Q u a l i t y
Many factors contribute to environmental quality
Pol-lution, the introduction of substances that affect or harm
the environment, is one of the biggest environmental concerns scientists face today
There are many different forms of pollution Some are natural, like volcanic eruptions Humans, however, cause most other forms of pollution
Air Pollution
Air is polluted by the introduction of harmful contami-nants into the atmosphere In and around big cities, smoke produced from factories and car emissions is
called smog Smog in the atmosphere can cause acid rain.
Recently, people with allergic reactions to smog have found the need to catch the smog alerts commonly read with the weather reports In addition to causing allergies, smog has been known to cause numerous health prob-lems, damage habitats, and disrupt ecosystems
Water Pollution
Many companies dispose their waste by pumping it into rivers, causing pollution in our water systems Sewage and pesticides are also factors that contribute to water pollution About one in three rivers in the United States
is polluted This presents serious problems to all life that depends on clean water for survival
Oceans also get polluted Garbage dumping, oil spills, and contaminated rivers are the biggest con-tributing polluters for our oceans This can be devastat-ing for countries that depend heavily on fishdevastat-ing for food
In 1989, the oil tanker Exxon Valdez smashed into some rocks and spilled 260,000 barrels of oil in Alaska The
– P E R S O N A L A N D S O C I A L P E R S P E C T I V E S I N S C I E N C E –
Trang 2consequences of this ocean contamination were felt by
land mammals and shore life in and around the area
Because the Earth is a closed system, all the pollution
we create eventually makes it back to our bodies or
back-fires in some other way It seems easier to dump mercury
waste, used in the extraction of gold from its ores, into
the ocean But the mercury waste can kill fish The fish
that survive contain the mercury we just spilled If we eat
the fish or a fish that had eaten a fish that survived,
the mercury enters our bodies Mercury causes brain
damage
Soil Pollution
Soil pollution occurs when chemicals such as pesticides,
fertilizers, toxic chemicals, or radioactive wastes are
introduced into the soil Considering that we all eat
pro-duce, this form of pollution directly affects us
Hazardous Waste
This type of waste refers to all kinds of substances that
are harmful to life, the environment, or is difficult to
break down Hazardous waste can cause cancer, genetic
disorders, and death
N a t u r a l a n d H u m a n - I n d u c e d
H a z a r d s
Floods, earthquakes, hurricanes, and drought are all examples of natural hazards All these conditions pro-duce stresses on the environment
■ Floods can erode the topsoil, destroy trees, grass,
and crops, and even tear down homes Floods can also contribute to the spread of disease by damag-ing sewage and waste disposal mechanisms The results of a flood can take years to undo
■ Earthquakes can tear up the land and produce
rock slides They can even cause flooding if a river
is redirected The effects of an earthquake in a big city can be devastating
■ Hurricanes can wreak havoc along the coasts,
destroying plants, trees, and even highways
Human-induced hazards include global warming, forest depletion, pollution, and nuclear waste Air pollu-tion that humans create directly affects global warming
It results from increased levels of carbon dioxide and
other gases (greenhouse gases), which produce a
green-house effect The greengreen-house effect occurs when the sun’s
rays, after hitting the Earth’s crust and bouncing back into space, get trapped in the atmosphere because of the greenhouse gases The trapped heat causes a rise in global temperature
– P E R S O N A L A N D S O C I A L P E R S P E C T I V E S I N S C I E N C E –
Trang 3TH E WO R L D’S M O S T renowned scientists once believed that the Earth was flat, that the sun revolved
around the Earth, and that human beings were already fully formed within a woman’s body and sim-ply had to grow to full size in the womb Science has a rich and often tumultuous history Driven by curiosity and desire to help humanity, scientists have made great progress in understanding nature This knowl-edge was, in most cases, accumulated incrementally, with one small discovery leading to another Theories were developed to unify and explain available facts Different interpretation of facts by different scientists has lead to controversies in the past Some major scientific discoveries created dramatic paradigm shifts—revolutions in our understanding of nature
S c i e n c e a s a H u m a n E n d e a v o r
What can possibly get someone to study for years, read science journals, repeat experiments countless times, write applications for funding, and present results? Just like a child reaches for a new object, touches it, looks at it, takes
it apart, and tries to make it work again, so the scientist looks at nature and tries to understand it The curiosity
C H A P T E R
History and Nature
of Science
IN THIS chapter, you will read about what drives science, the nature
of scientific knowledge, and how the body of scientific knowledge grows and changes over time You will also find a brief description of some foundation-shaking advances in science
28
Trang 4almost seems to be innate, and the thrill that comes from
understanding nature or making a new experiment work
is well expressed in the following quote:
“I do not think there is any thrill that can go through the
human heart like that felt by the inventor as he sees some
creation of the brain unfolding to success Such emotions
make a man forget food, sleep, friends, love, everything.”
—Nikola Tesla, physicist and inventor
Scientists are driven by curiosity and the thrill that
comes from understanding or creating something At the
same time, they are motivated by the desire to improve the
quality of life—making everyday chores easier, curing
diseases, and solving global and environmental
prob-lems Scientists also seek to use, predict, and control
nature—to use sunlight and water for electrical power
generation, to forecast the weather and earthquakes, to
prevent floods, and to prevent infection of crops and
cattle
The result is that over the years, our understanding of
science has greatly improved Humanity has gone from
attributing disease to supernatural beings to developing
vaccines, antibiotics, and gene therapy to prevent and
cure disease Since Thales of Miletus proposed in 625 B.C
that the Earth is a disc that floats on water, humans have
discovered the true nature of their planet, have observed
other galaxies, and have landed on the moon The
im-mense progress people have made in science is well
expressed in this quote:
“The simplest schoolboy is now familiar with truths for
which Archimedes would have sacrificed his life.”
—Ernest Renan, philosopher
T h e N a t u r e o f S c i e n t i f i c
K n o w l e d g e
Scientific knowledge is rooted in factual information that
is compiled and interpreted to develop theories While
scientists can’t help believing and hoping—that their
experiments or inventions will work; that they will solve
a problem; that their theories are correct—experiments
are designed to eliminate, as much as possible, the effects
of the beliefs and hopes of the scientist performing them
Different scientists often get conflicting data Even the same scientist’s data is not always consistent Differences
in experimental procedure, which the scientists may or may not be aware of, can all lead different scientists to different conclusions or even the same scientist to dif-ferent conclusions at two difdif-ferent times Occasionally, this leads to controversy In the sections below, we will briefly describe the nature of scientific knowledge and how beliefs and controversies play a part
Facts
Scientific knowledge is dependent and inseparable from facts The principles of the scientific method guide sci-entists to observe facts and to propose hypotheses that can be tested by observing other facts A hypothesis that can’t be verified by collecting scientific facts is not con-sidered part of the domain of science
Theories
Just as a collection of bricks does not equal a house, a col-lection of facts does not equal science Scientific facts, like bricks, need to be sorted and stacked properly Their relationships to each other matter and need to be estab-lished Scientists must be able to envision the end result, the way an architect needs to have an idea of what a house should look like For scientists, the house is the theory—something that unites the facts and makes them meaningful and useful Theories are formed when a con-nection between facts is first observed The theories are then developed by looking for more facts that fit into the theory and by modifying the theory to include or explain the facts that do not fit
Beliefs
One of the most difficult tasks of a scientist is to remain objective and prevent beliefs from affecting observations This is not to say that scientists purposely hide facts that don’t support their hypotheses or that are in conflict with their beliefs Most scientists are well trained to report everything they observe, even if it’s inconsistent with what was previously observed and even if it seems unim-portant However, it is in human nature to notice and remember the things that we believe in and that we expect
This is a form of intellectual prejudice If Bob believes that Julie hates him, he will tend to notice only Julie’s negative behavior toward him such as not saying
– H I S T O R Y A N D N AT U R E O F S C I E N C E –
Trang 5hello and making a joke about him He will also tend to
interpret Julie’s actions in a negative way For example, if
Julie says that she can’t go to the movies, Bob will take
that as evidence for his hypothesis that Julie hates him
However, this is not necessarily true—Julie may have too
much homework Bob could also disregard or
misinter-pret the nice things that Julie does—it could be a
coinci-dence that Julie sat next to him and that she called him
(maybe she just needed something) Scientists can’t help
but occasionally do the same thing For example, a
sci-entist who smokes may note the great number of people
who smoke and don’t get cancer, and attribute the fact
that some people who smoke and do get cancer to
pol-lution sensitivity or lack of proper nutrition
Marie Curie, a two-time Nobel Prize winner, refused
to note overwhelming data that suggested that radium,
an element she had discovered, was a health hazard This
inability to see was not caused by lack of training, as
Curie was a sufficiently trained scientist whose doctoral
thesis was considered the greatest single contribution to
science by a doctoral student The inability to see is
caused by a blindfold made of hopes and beliefs that
scientists, like all other people, can’t help having once in
a while
“Man can’t help hoping even if he’s a scientist He can
only hope more accurately.”
—Karl Menninger, psychiatrist
Controversies
Conflicting data, or facts that seemingly can’t be
incor-porated into the same theory, often cause controversies
among scientists The controversies can polarize the
sci-entific community, as well as the general population,
especially in matters of public or social importance In
the past, controversies also sprang up between scientists
and religious establishments Copernicus shook up the
church when he proposed that planets revolved around
the sun Similarly, Darwin caused a lot of controversy
when he presented his theory of evolution There is still
some debate on whether evolution theory should be
taught in public schools
The nature of light was not very well understood for
a long time There were observations that suggested that
light is a stream of particles, as well as that light is a wave
Newton’s belief that light was a series of particles
pre-vailed from the 1700s until 1873, when James Clerk Maxwell showed that light is an electromagnetic phenomenon Although many scientists before Maxwell found evidence for the wave nature of light, Newton’s great reputation and social class allowed his ideas to pre-vail until there was enough evidence to the contrary Max Planck’s theory about the resolution of controversies is slightly more cynical:
“A new scientific truth does not triumph by convincing
its opponents and making them see the light, but rather because its opponents eventually die, and a new genera-tion grows up that is familiar with it.”
—Max Planck, physicist
H i s t o r i c a l P e r s p e c t i v e s
All sciences are rooted in philosophy, which they stemmed from, as knowledge in different sciences accu-mulated and became more specialized Areas of science today include very specific subjects, such as oceanogra-phy, crystallograoceanogra-phy, and genetic engineering, as well as interdisciplinary subjects, such as biochemistry and bio-physics
Progress in science usually occurs in small incremen-tal steps For example, nucleic acids (building blocks of DNA) were discovered in the nuclei of cells in 1869 After that, progress was made Different scientists made con-tributions to the study of DNA However, scientists did not solve the structure of DNA until 1953, when Ros-alind Franklin, James Watson, and Francis Crick obtained their results About twenty years later, the first genome sequencing was presented—for a virus that had
a relatively small amount of genetic material More recently, the Human Genome Project was completed Hundreds of scientists worked on this largest single fed-erally funded project to date with the goal of identifying all human genes and mapping out the human DNA Sci-entific advances usually depend on other sciSci-entific advances, and progress is usually gradual Many scien-tists put in a lot of time before a new concept becomes completely understood and before a new area of science develops
Occasionally, however, there are leaps in scientific progress Such leaps represent major discoveries that
– H I S T O R Y A N D N AT U R E O F S C I E N C E –
Trang 6shake the foundations of understanding and lead to new
modes of thinking Thomas Kuhn, philosopher of
sci-ence, called such discoveries paradigm shifts
Here are some major advances in science
■ 420 B.C.: Hippocrates begins the scientific study
of medicine by maintaining that diseases have common causes
■ 260 B.C.: Archimedes discovers the principle of buoyancy
■ 180 A.D.: Galen studies the connection between paralysis and severance of the spinal cord
■ 1473: Copernicus proposes a heliocentric system
■ 1581: Galileo finds that objects fall with the same acceleration
■ 1611: Kepler discovers total internal reflection and thin lens optics
■ 1620: Francis Bacon discusses the principles of the scientific method
■ 1687: Newton formulates the laws of gravity
■ 1789: Lavoisier states the law of conservation of energy
■ 1837: Darwin uses natural selection to explain evolution
■ 1864: James Clerk Maxwell shows that light is an electromagnetic phenomenon
– H I S T O R Y A N D N AT U R E O F S C I E N C E –