Science aims to explain and understand

Science as a collective institution aims to produce more and more accurate natural explanations of how the natural world works, what its components are, and how the world got to be the way it is now. Classically, science's main goal has been building knowledge and understanding, regardless of its potential applications — for example, investigating the chemical reactions that an organic compound undergoes in order to learn about its structure. However, increasingly, scientific research is undertaken with the explicit goal of solving a problem or developing a technology, and along the path to that goal, new knowledge and explanations are constructed. For example, a chemist might try to produce an antimalarial drug synthetically and in the process, discover new methods of forming bonds that can be applied to making other chemicals. Either way (so-called "pure" or "applied" research), science aims to increase our understanding of how the natural world works.

A coelacanth

The knowledge that is built by science is always open to question and revision. No scientific idea is ever once-and-for-all "proved." Why not? Well, science is constantly seeking new evidence, which could reveal problems with our current understandings. Ideas that we fully accept today may be rejected or modified in light of new evidence discovered tomorrow. For example, up until 1938, paleontologists accepted the idea that coelacanths (an ancient fish) went extinct at the time that they last appear in the fossil record — about 80 million years ago. But that year, a live coelacanth was discovered off the coast of South Africa, causing scientists to revise their ideas and begin to investigate how this animal survives in the deep sea.

Despite the fact that they are subject to change, scientific ideas are reliable. The ideas that have gained scientific acceptance have done so because they are supported by many lines of evidence. These scientific explanations continually generate expectations that hold true, allowing us to figure out how entities in the natural world are likely to behave (e.g., how likely it is that a child will inherit a particular genetic disease) and how we can harness that understanding to solve problems (e.g., how electricity, wire, glass, and various compounds can be fashioned into a working light bulb). For example, scientific understandings of motion and gases allow us to build airplanes that reliably get us from one airport to the next. Though the knowledge used to design airplanes is technically provisional, time and time again, that knowledge has allowed us to produce airplanes that fly. We have good reason to trust scientific ideas: they work!

		A SCIENCE PROTOTYPE: RUTHERFORD AND THE ATOM Ernest Rutherford's investigations were aimed at understanding a small, but illuminating, corner of the natural world: the atom. He investigated this world using alpha particles, which are helium atoms stripped of their electrons. Rutherford had found that when a beam of these tiny, positively-charged alpha particles is fired through gold foil, the particles don't stay on their beeline course, but are deflected (or "scattered") at different angles. Rutherford wanted to figure out what this might tell him about the layout of an atom. Rutherford's story continues as we examine each item on the Science Checklist. To find out how this investigation measures up against the rest of the checklist, read on.

For further information log on website :
http://undsci.berkeley.edu/article/0_0_0/whatisscience_04

Science works with testable ideas

Only testable ideas are within the purview of science. For an idea to be testable, it must logically generate specific expectations — in other words, a set of observations that we could expect to make if the idea were true and a set of observations that would be inconsistent with the idea and lead you to believe that it is not true. For example, consider the idea that a sparrow's song is genetically encoded and is unaffected by the environment in which it is raised, in comparison to the idea that a sparrow learns the song it hears as a baby. Logical reasoning about this example leads to a specific set of expectations. If the sparrow's song were indeed genetically encoded, we would expect that a sparrow raised in the nest of a different species would grow up to sing a sparrow song like any other member of its own species. But if, instead, the sparrow's song were learned as a chick, raising a sparrow in the nest of another species should produce a sparrow that sings a non-sparrow song. Because they generate different expected observations, these ideas are testable. A scientific idea may require a lot of reasoning to work out an appropriate test, may be difficult to test, may require the development of new technological tools to test, or may require one to make independently testable assumptions to test — but to be scientific, an idea must be testable, somehow, someway. If an explanation is equally compatible with all possible observations, then it is not testable and hence, not within the reach of science. This is frequently the case with ideas about supernatural entities. For example, consider the idea that an all-powerful supernatural being controls our actions. Is there anything we could do to test that idea? No. Because this supernatural being is all-powerful, anything we observe could be chalked up to the whim of that being. Or not. The point is that we can't use the tools of science to gather any information about whether or not this being exists — so such an idea is outside the realm of science.

		A SCIENCE PROTOTYPE: RUTHERFORD AND THE ATOM Before 1910, Ernest Rutherford and many other scientists had the idea that the positive charge and the mass of an atom were evenly distributed throughout the whole atom, with electrons scattered throughout. You can imagine this model of the atom as a loosely packed snowball (the positive mass of the atom) with a few tiny grains of sand (the electrons) scattered throughout. The idea that atoms are arranged in this way can be tested by firing an alpha particle beam through a piece of gold foil. If the idea were correct, then the positive mass in the gold foil would be relatively diffuse (the loosely packed snow) and would allow the alpha particles to pass through the foil with only minor scattering. Rutherford's story continues as we examine each item on the Science Checklist. To find out how this investigation measures up against the rest of the checklist, read on.

For further information log on website :
http://undsci.berkeley.edu/article/0_0_0/whatisscience_05

Science Relies on Evidence

Ultimately, scientific ideas must not only be testable, but must actually be tested — preferably with many different lines of evidence by many different people. This characteristic is at the heart of all science. Scientists actively seek evidence to test their ideas — even if the test is difficult and means, for example, spending years working on a single experiment, traveling to Antarctica to measure carbon dioxide levels in an ice core, or collecting DNA samples from thousands of volunteers all over the world. Performing such tests is so important to science because in science, the acceptance or rejection of a scientific idea depends upon the evidence relevant to it — not upon dogma, popular opinion, or tradition. In science, ideas that are not supported by evidence are ultimately rejected. And ideas that are protected from testing or are only allowed to be tested by one group with a vested interest in the outcome are not a part of good science. To learn more about testing by special interest groups and how that can inadvertently lead to bias (and bad science), take an advanced side trip to Who pays for science?

		A SCIENCE PROTOTYPE: RUTHERFORD AND THE ATOM Ernest Rutherford's lab tested the idea that an atom's positive mass is spread out diffusely by firing an alpha particle beam through a piece of gold foil, but the evidence resulting from that experiment was a complete surprise: most of the alpha particles passed through the gold foil without changing direction much as expected, but some of the alpha particles came bouncing back in the opposite direction, as though they had struck something dense and solid in the gold foil. If the gold atoms were really like loosely packed snowballs, all of the alpha particles should have passed through the foil, but they did not! From this evidence, Rutherford concluded that their snowball model of the atom had been incorrect, even though it was popular with many other scientists. Instead, the evidence suggested that an atom is mostly empty space and that its positive charge is concentrated in a dense mass at its core, forming a nucleus. When the positively charged alpha particles were fired at the gold foil, most of them passed through the empty space of the gold atoms with little deflection, but a few of them ran smack into the dense, positively charged nucleus of a gold atom and were repelled straight back (like what would happen if you tried to make the north poles of two strong magnets touch). The idea that atoms have positively charged nuclei was also testable. Many independent experiments were performed by other researchers to see if the idea fit with other experimental results.Rutherford's story continues as we examine each item on the Science Checklist. To find out how this investigation measures up against the rest of the checklist, read on.

For further information log on website :
http://undsci.berkeley.edu/article/0_0_0/whatisscience_06

Science is embedded in the scientific community

The progress of science depends on interactions within the scientific community — that is, the community of people and organizations that generate scientific ideas, test those ideas, publish scientific journals, organize conferences, train scientists, distribute research funds, etc. This scientific community provides the cumulative knowledge base that allows science to build on itself. It is also responsible for the further testing and scrutiny of ideas and for performing checks and balances on the work of community members.

Scientists sometimes work alone and sometimes work together, but communication within the scientific community is always important. In addition, much scientific research is collaborative, with different people bringing their specialized knowledge to bear on different aspects of the problem. For example, a 2006 journal article on regional variations in the human genome was the result of a collaboration between 43 people from the U.K., Japan, the U.S., Canada, and Spain! Even Charles Darwin, who initially investigated the idea of evolution through natural selection while living almost as a hermit at his country estate, kept up a lively correspondence with his peers, sending and receiving numerous letters dealing with his ideas and the evidence relevant to them.In rare cases, scientists do actually work in isolation. Gregor Mendel, for example, figured out the basic principles of genetic inheritance as a secluded monk with very little scientific interaction. However, even in such cases, research must ultimately involve the scientific community if that work is to have any impact on the progress of science. In Mendel's case, the ultimate involvement of the scientific community through his published work was critical because it allowed other scientists to evaluate those ideas independently, investigate new lines of evidence, and develop extensions of his ideas. This community process may be chaotic and slow, but it is also crucial to the progress of science.

		A SCIENCE PROTOTYPE: RUTHERFORD AND THE ATOM Ernest Rutherford (right) and Hans Geiger in the physics laboratory at Manchester University, England, circa 1912. Permission of the Alexander Turnbull Library, Wellington, New Zealand, must be obtained before any re-use of this image. Reference number: PAColl-0091-1-011. Though Ernest Rutherford came up with the idea that atoms have positively charged nuclei, the research that led to this idea was a collaborative effort: Rutherford was assisted by Hans Geiger, and the critical alpha-scattering experiment was actually carried out by Ernest Marsden, an undergraduate student working in Rutherford's lab. Furthermore, after his discovery of the layout of the atom, Rutherford published a description of the idea and the relevant evidence, releasing it to the scientific community for scrutiny and evaluation. And scrutinize they did. Niels Bohr noticed a problem with Rutherford's idea: there was nothing keeping the orbiting electrons from spiraling into the nucleus of the atom, causing the whole thing to collapse! Bohr modified Rutherford's basic model by proposing that electrons had set energy levels, which helped solve the problem and earned Bohr a Nobel Prize. Since then, many other scientists have built on and modified Bohr's model. Lithium atoms, diagrammed in the Rutherford and Bohr models. Rutherford's model does not differentiate between any of the electrons, while Bohr's places electrons into orbits with set energy levels. Rutherford's story continues as we examine each item on the Science Checklist. To find out how this investigation measures up against the rest of the checklist, read on.

For further information log on website :
http://undsci.berkeley.edu/article/0_0_0/whatisscience_07