A Note on the Nature of Science ideas that a sciont report these ob ervations with complete honesty. c met Is a ny a colle scientific method. othesis and er iment path,a scientist poses a Seience is both a way of thinking about the natura hypothesis,then subjects it toexperimental test.Many of such thinking.The and st science now directly from its reliance on ideas that car by James Watson and francis Crick led to the hypothesis that have predictive ress of science rests the discovery of DNA and RNA o on a found ational assumption that is often unstated but Watson and Crick produced their DNA structure through a process of building and calculations used data collected by othe to this underlying assumption as the scientists.Many be method of dis Science could not succeed in a universe that played 1831 voyage on HM.S Beagle among them)helped to cata log its the can be reproducibly substantiated and(2)can be used launch pr to ther planets An analog of hypothesis s that sci and exper nent I and ded tated translation or the information in me ger RN different from those applied by no Not but it may lack extensive experimental substantiation ity often plays a role. The than a hunch.It i and of I catalysts by Thoma oberyanons t on an red to exploit them tion can also lead to important advances.The polymeras is thus a s for further advance hain reaction (PCR a central part of bi dated on many fronts.it can be accept d as a fact during a road trip in northern Califomia in 1983. In one what nstitutes science se man paths to oscientific discovery ca n seen or y whe er or not it blishad in th peer-revie rely on rep scientific jourals worldwid e pu ush some 1.4 millior of the ideas. insights,and experimental acts tha orma tion that is the birthright of ev human being by scientists anywhere in the world.All can be Scientists are individuals who rigorously apply Iby other scientists to build new hypotheses and the nake A lead to inlorm Ton tha pline does not make one a scientist.nor does the lack ing our universe requires hard work.At the same time of such a degree prevent one from making important no human endeavor is more exciting and potentially The eding,t nd itI n this twenty-first century, a typical science education often leaves the philosophical underpinnings of sci￾ence unstated, or relies on oversimplified definitions. As you contemplate a career in science, it may be useful to consider once again the terms science, scientist, and scientific method. Science is both a way of thinking about the natural world and the sum of the information and theory that result from such thinking. The power and success of science flow directly from its reliance on ideas that can be tested: information on natural phenomena that can be observed, measured, and reproduced and theories that have predictive value. The progress of science rests on a foundational assumption that is often unstated but crucial to the enterprise: that the laws governing forces and phenomena existing in the universe are not subject to change. The Nobel laureate Jacques Monod referred to this underlying assumption as the “postulate of objec￾tivity.” The natural world can therefore be understood by applying a process of inquiry—the scientific method. Science could not succeed in a universe that played tricks on us. Other than the postulate of objectivity, sci￾ence makes no inviolate assumptions about the natural world. A useful scientific idea is one that (1) has been or can be reproducibly substantiated and (2) can be used to accurately predict new phenomena. Scientific ideas take many forms. The terms that sci￾entists use to describe these forms have meanings quite different from those applied by nonscientists. A hypoth￾esis is an idea or assumption that provides a reasonable and testable explanation for one or more observations, but it may lack extensive experimental substantiation. A scientific theory is much more than a hunch. It is an idea that has been substantiated to some extent and provides an explanation for a body of experimental observations. A theory can be tested and built upon and is thus a basis for further advance and innovation. When a scientific theory has been repeatedly tested and vali￾dated on many fronts, it can be accepted as a fact. In one important sense, what constitutes science or a scientific idea is defined by whether or not it is published in the scientific literature after peer review by other working scientists. About 16,000 peer-reviewed scientific journals worldwide publish some 1.4 million articles each year, a continuing rich harvest of informa￾tion that is the birthright of every human being. Scientists are individuals who rigorously apply the scientific method to understand the natural world. Merely having an advanced degree in a scientific disci￾pline does not make one a scientist, nor does the lack of such a degree prevent one from making important scientific contributions. A scientist must be willing to challenge any idea when new findings demand it. The ideas that a scientist accepts must be based on measur￾able, reproducible observations, and the scientist must report these observations with complete honesty. The scientific method is actually a collection of paths, all of which may lead to scientific discovery. In the hypothesis and experiment path, a scientist poses a hypothesis, then subjects it to experimental test. Many of the processes that biochemists work with every day were discovered in this manner. The DNA structure elucidated by James Watson and Francis Crick led to the hypothesis that base pairing is the basis for information transfer in polynucleotide synthesis. This hypothesis helped inspire the discovery of DNA and RNA polymerases. Watson and Crick produced their DNA structure through a process of model building and calculation. No actual experiments were involved, although the model building and calculations used data collected by other scientists. Many adventurous scientists have applied the process of exploration and observation as a path to dis￾covery. Historical voyages of discovery (Charles Darwin’s 1831 voyage on H.M.S. Beagle among them) helped to map the planet, catalog its living occupants, and change the way we view the world. Modern scientists follow a similar path when they explore the ocean depths or launch probes to other planets. An analog of hypothesis and experiment is hypothesis and deduction. Crick rea￾soned that there must be an adaptor molecule that facili￾tated translation of the information in messenger RNA into protein. This adaptor hypothesis led to the discovery of transfer RNA by Mahlon Hoagland and Paul Zamecnik. Not all paths to discovery involve planning. Serendip￾ity often plays a role. The discovery of penicillin by Alex￾ander Fleming in 1928 and of RNA catalysts by Thomas Cech in the early 1980s were both chance discoveries, albeit by scientists well prepared to exploit them. Inspira￾tion can also lead to important advances. The polymerase chain reaction (PCR), now a central part of biotechnology, was developed by Kary Mullis after a flash of inspiration during a road trip in northern California in 1983. These many paths to scientific discovery can seem quite different, but they have some important things in common. They are focused on the natural world. They rely on reproducible observation and/or experiment. All of the ideas, insights, and experimental facts that arise from these endeavors can be tested and repro￾duced by scientists anywhere in the world. All can be used by other scientists to build new hypotheses and make new discoveries. All lead to information that is properly included in the realm of science. Understand￾ing our universe requires hard work. At the same time, no human endeavor is more exciting and potentially rewarding than trying, and occasionally succeeding, to understand some part of the natural world. 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