Cosmology and our View of the World
Determinism and Indeterminism
Lead: Marty Rowley & Sam Schweizer
Summary by Dave J Ducharme
Marty and Sam started their discussion of Determinism and Indeterminism by passing out a handout with explanations and descriptions of the following topics: Albert Einstein, Niels Bohr, Quanta, Complementarity, Heisenberg’s Uncertainty Principle, Newtonian Clockwork, Timeline vs. Cycle, Chaotic Systems, Bifurcation Point, Butterfly Effect, Participant Observation, and Free Will. Also, the following questions were listed by the presenters:
Professor deVries did point out that Daniel Dennett’s views as listed are not entirely accurate. Professor deVries said that Dennett certainly allows for choice; what he denies is that in order to be free such choice must be uncaused or undetermined. Marty opened the presentation by asking for a volunteer from the audience. He had a line of dominos stacked on the table. He asked the volunteer to push over the domino on one end of the line. When he did so the rest of the dominos were knocked over in succession. This demonstration was meant to illustrate the deterministic view that Einstein had of the universe.
Einstein believed in the certainty of the universe, that it must of necessity be “rational” in that it behaves according to natural universal laws that are determined and exist independently and objectively of human observers. Because of this faith in certainty, he broke with Niels Bohr, as Einstein refused to believe “the Good Lord plays dice with the universe.”
Then Marty asked Dr. Davis if he would pull a King from an ordinary deck of cards. Dr. Davis attempted but could not pull a king. Marty then explained that this exemplified Niels Bohr’s view of an indeterministic universe.
Bohr made monumental contributions to quantum theory and is responsible for the theory of complementarity. Bohr believed the universe was fundamentally indeterministic, having various debates with Einstein about this topic throughout the years.
Marty then began discussing quantum mechanics and the question of what happens to light energy that hits a black body . Max Planck discovered that light energy is given off in small amounts known as quanta. Bohr expanded upon this concept by suggesting that not only light but also the energy of atoms is quantized.
At this point the discussion led to the dual properties of light. Light was explained as behaving both like a wave and like a particle under different circumstances. This is known as complementarity; the idea that two seemingly mutually exclusive statements can be true at once.
The next concept discussed was Heisenberg’s Uncertainty Principle. It explains that an electron’s speed and location cannot be simultaneously known. Marty gave the example of the half life of radium. We know how long the half life time is but we cannot know when the individual atoms will decay.
Sam took over the next part of the discussion beginning with Chaos Theory. According to Sam, nature is based on chaotic systems, systems which are nonlinear and not predictable. Sam had an illustration on the chalk board to explain this effect. It contained a hill and a trough with a ball at the top of the hill. If the ball is pushed into the trough it will have a very observable behavior that is easily predictable. However, if the ball is pushed in the opposite direction, away from the trough, it will enter another system entirely and thus cannot be predicted. He did mention though that chaotic systems do not overrule the possibility of determinism.
The discussion then went back to Marty with the topic of Free Will. He basically introduced the questions included on the handout and opened the floor for discussion.
One of the first questions brought up was on the topic of chaotic systems and their relation to determinism and indeterminism. A student asked if indeterminism and chaos theory were one and the same. Marty, Sam, and the professors all answered the question, explaining that they are two separate things. They explained that determinism or indeterminism and predictability do not coincide. In a deterministic universe, not everything can be predicted and in an indeterministic universe some things can be predicted. Chaos theory does not state that prediction is impossible, just that it is so complex that the likelihood of accurately predicting something is next to zero.
Professor deVries then added in that things at the quantum level are intrinsically indeterministic because, according to Bohr, there is no determinate state in which quantum reality can be said to be. The state of the particle depends upon the kind of measurements we make. Professor deVries explained that if we look for particles, we find particles; and if we look for waves we find waves. The reality itself is neither wave nor particle. To this, a student asked if we could observe quanta without interfering would we see a deterministic environment? To which deVries replied that it is not possible to observe without interacting.
Under the influence of Bohr’s ideas, most of the class came to the conclusion that things on the quantum level must be indeterministic. However, many people also came to the conclusion that larger systems, such as those described by chaos theory, appear to be deterministic. Professor deVries shared his opinion that it is possible for a determinate system to have an indeterminate base.
As a rebuttal, a few students brought up the argument that our current lack of knowledge cannot be held up against determinism. They felt that the tools we have now may not be accurate enough to measure quanta but our future technology may be able to do it so, at best, determinism can not be entirely omitted from possibility. Their opinion was that the universe is deterministic and is base at the quantum level is as well, we just cannot observe it properly at this time.