Philosophy of Space and Time Essay
Philosophy of Space and Time
At the end of the nineteenth century, physicists were looking back at an era of progress unrivaled in known history. Classical, or Newtonian, physics explained the motion of objects in space and on earth, Kepler’s laws accurately predicted planetary motion, and Maxwell’s electromagnetic unified electricity and magnetism theory and predicted, correctly, that electromagnetic waves behaved exactly like light; paving the way for the recognition that light itself was an electromagnetic wave.
It appeared that the world was explained. It was not to be. Two revolutionary theories were introduced that changed forever the way in which scientists and lay people alike view the universe. These were the Theory of Relativity and Quantum Physics (Giancoli 730) . Physicists at the turn of the century assumed that any wave must travel through some medium. This assumption required there to be some transparent substance in space that would allow light to propagate through it, much like a ripple on the water.
They knew that this could not be air, since light traveled from stars to the earth through the emptiness of space. Another medium had to be responsible. This medium was named the Ether and it was thought to exist in all space. They understood that the ether had a zero density, since it was very difficult to detect (Giancoli 731). Two physicists in the 1880’s, Michelson and Morley, designed a clever experiment that they thought would determine the speed of the Earth in orbit around the sun.
They anticipated being able to measure the speed of light in different orientations. They anticipated that the speed would vary with the orientation of the light wave to the ether. What they discovered was that the speed was constant. They believed there experiment was a failure. What their experiment showed, although they did not accept it, was that the ether did not exist. In 1905 Albert Einstein proposed a theory that reconciled this and other issues.
This theory would change how scientists and lay people viewed space, time, mass, and energy (Giancoli 730). Einstein’s equation relating mass and energy, E = MC2, is easily recognizable. It brings together matter and energy as different forms of the same substance. This would imply that mass could be converted directly to energy, and vice versa. This radical departure from classical physics had several implications, both for scientists and for our culture. For scientists, the theory of relativity established the ultimate speed limit.
The speed of light in a vacuum, c, is as fast as anything can go (Giancoli 748). Culturally, the discovery of relativity and quantum physics made possible such things as nuclear power, nuclear weapons, and medical imagery such as MRI Scans, CAT Scans, and PET scans. The advent of nuclear weapons changed our society. Nuclear attacks were a common theme in Hollywood films. Citizens built there own bomb shelters, argued the pros and cons of the nuclear power industry, and have enjoyed the advances in medicine.
Indeed, our society now takes for granted these advances, and assumes that there will be a continued rapid advance as our knowledge base improves. Cosmology, or the study of the universe, has benefited from the theory of relativity. Many phenomenons, such as black holes, are only describable in terms of relativity and quantum physics. The advent of space telescopes, radio telescopes, and optical telescopes that detect emissions outside of the visible spectrum have shown the world the images of a universe unlike the one that was believed to exist just a hundred years ago (Giancoli 914-942).
The search for extra-terrestrial life was instigated with the federal governments backing. The private citizens embraced this search, of 3 so much so that when the government quit funding SETI, individual citizens continued to support it. The discovery of relativity, quantum physics, and the new nature of cosmology has changed not only the scientific community but society as a whole. SETI, CAT scans, an Einstein’s name are household terms. The changes in perception of the world around us really cannot be overstated.