? ???In science, a theory is an idea that. once confirmed by experiment or meticulous observation as certainty. becomes a scientific 1aw. Facts are generally obtained through empirical research (through observation or experiment). Occasionally: however, facts that are not easy to obtain directly are deduced from theory. good example is the work done in the 1840s on Saturn's rings by the great Scottish physicist James lerk Maxwell. t the time, astronomers had observed three concentric rings about Saturn, all in the same plane. They knew that at least some regions of the rings must be quite thin, since in some areas the planet behind could be plainly seen. side from that, their structure was an intriguing mystery. Maxwell carried out a careful theoretical and highly mathematical treatment, and concluded that the rings could not be single solid or liquid units, since mechanical forces acting upon rings of such immense size would break them up. He suggested instead that the rings must be composed of vast numbers of individual solid particles rotating in separate concentric orbits at different speeds. He even drew some conclusions about how large the particles would be and how fast they would move.

???????For many decades there was no way of testing Maxwell's conclusion, but in the latter years of the twentieth century. observations-particularly those from Voyager spacecraft confirmed Maxwell's conclusions. The particles are composed of window impure ice, or at least are ice covered. Radar observations have even confirmed the range of masses and speeds predicted by Maxwell. This was a remarkable achievement on Maxwell's part. Or the basis of theory; he had arrived at factual information that could not be directly obtained for almost a century and a half.

???????Scientific work is best done with a theory in mind. It does not matter if the theory is proved wrong: it will nevertheless guide the initial experiments, which may lead to the correct theory. Paradoxically, people occasionally do much better with the wrong theory than with the right one, and there is one rather striking example of this. y the year 1900, physicists had become aware of the properties of radio waves, which they knew to be of the same character as light but with much longer wavelengths. Experiments had shown that radio waves (unlike 1ight) would pass through walls because of the long wavelengths, and that like light they travel in straight lines.

???????One of the people working on radio waves at the time was the Italian Guglielmo Marconi. Unlike almost everyone else working on them, he knew hardly any physics. (Hence, the award to him of the 909 Nobel Prize for physics amazed and horrified most physicists.) He did not really understand the properties of electromagnetic waves. and did not even realize that radio waves were of that type He said that his waves were Marconi waves, and that, instead of traveling in straight lines, they could be controlled by him to go to any point he chose. This was nonsense, but his ignorance of physics led him to try to send a signal across the tlantic Ocean. No other physicist thought this was a reasonable thing to try -how could a wave, which has to travel in a straight line, possibly travel so far over the curved surface of the tlantic? On ecember 12. 1901. Marconi's assistant sent signals across the tlantic Ocean, from ornwall, England, to St. John's, Newfoundland. where Marconi was apparently just able to receive them.

???????Physicists were quite correct in thinking that radio waves go in straight lines. How, then, can a radio signal go across the tlantic, in view of Earth's curved surface? The most plausible answer is that they are reflected in some way. In 1902. the ritish physicist Oliver Heaviside and the merican physicist rthur Edwin Kennelly postulated the existence of a layer in the upper atmosphere in which they thought that molecules would be ionized. meaning they would carry electric charges. Such a layer would reflect the waves from the upper atmosphere and allow them to travel great distances over Earth's surface.

1.In science, a theory is an idea that. once confirmed by experiment or?meticulous?observation as certainty. becomes a scientific 1aw. Facts are generally obtained through empirical research (through observation or experiment). Occasionally: however, facts that are not easy to obtain directly are deduced from theory. good example is the work done in the 1840s on Saturn's rings by the great Scottish physicist James lerk Maxwell. t the time, astronomers had observed three concentric rings about Saturn, all in the same plane. They knew that at least some regions of the rings must be quite thin, since in some areas the planet behind could be plainly seen. side from that, their structure was an intriguing mystery. Maxwell carried out a careful theoretical and highly mathematical treatment, and concluded that the rings could not be single solid or liquid units, since mechanical forces acting upon rings of such immense size would break them up. He suggested instead that the rings must be composed of vast numbers of individual solid particles rotating in separate concentric orbits at different speeds. He even drew some conclusions about how large the particles would be and how fast they would move.