Essay Questions

According to Hawking, why is a theory always provisional?

If you think about most of the scientific theories with which we are all familiar - we have at least heard mention of them, even if we do not fully understand what each one is stating - they seem to have been around an awfully long time. This would suggest, to the uninitiated at least, that they have been proven on multiple occasions, and that they must, therefore, be facts. At the very least, they must be true.

According to Hawking, this can never be the case. Just because a theory has been proven to be true over a thousand successive times, there is no guarantee that the next thousand attempts might offer up a different result, which would render the initial experiments null and void. Physics is only as non-provisional as its next experiment.

Aristotle is most familiar to the public as a philosopher. What contribution did he make to the world of physics?

In Aristotle's day, there was not really a concept of science as a whole, or in physics as a component of that. What there was, however, was an enormous interest in the place where philosophy and cosmology collided to become the theory of how the Earth came to be, and how it works. Aristotle was a respected astronomer (had he been born generations later he would have been a preeminent astrophysicist.). He was the first mainstream philosopher to believe that the Earth was round - prior to his conclusions, most people believed it to be flat. This realization literally changed the direction of mankind and took away the limits of what was achievable.

However, Aristotle also grasped some astronomical concepts differently. He continued to believe that the Sun went around the Earth, which is the opposite of what we know to be true today, although his beliefs were accepted as facts until the fifteenth century when astronomer Nicolas Copernicus suggested that the Earth orbited the Sun.

Aristotle also contributed to the discussion about the origin of the Universe, which he believed to date from the beginning of time, which he in tern went back forever. This belief took far longer to debunk; it was not until 1929 that Edwin Hubble discovered that rather than moving towards each other, the galaxies are actually moving away from each other, which means that contrary to what Aristotle believed, there was a time when all the galaxies were actually together, and that the beginning of their movement away from each other was the beginning of the universe as we understand it.