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Worldviews Part 3- Recent Developments in Science and Worldviews

08/08/2014

Chapter 23: The Special Theory of Relativity

This theory is “special” because it applies to special cases, in contrast to the general theory of relativity, which applies to much more. The theory is based on the constancy of the speed of light (why do we believe it to be constant?) which states that the speed of light in a vacuum will always be the same. Also the principle of relativity, which states that there is no privileged point of view from which one is at motion and another at rest. Together these lead to the strange conclusion that time dilates the faster you go. The faster you are going, the slower time moves relative to non-moving things. Objects also shrink as they move faster.

Much like Newtonian physics challenged common views of inertia and celestial bodies, the special theory of relativity challenges common beliefs about time and distance.

Chapter 24: The General Theory of Relativity

General relativity is based on two main aspects. The principle of general covariance says that the laws of physics are the same for all reference frames. The principle of equivalence states that the effects of acceleration are indistinguishable from the effects of gravity.

This theory changes our view of gravity in an important way. Instead of Newtonian action at a distance, gravity consists of the bending of space-time as objects move in straight lines. This forces us to take an instrumentalist view of Newtonian physics.

Chapter 25: Overview of the Empirical Facts, Mathematics, and Interpretations of Quantum Theory

DeWitt emphasizes the difference between agreed facts, the mathematical model, and the interpretation:

there are at least three separate issues that should be kept distinct, these being (a) the quantum facts, that is, empirical facts involving quantum entities, (b) quantum theory itself, by which I will mean the mathematical core of quantum theory, and (c) interpretations of quantum theory, which involve philosophical questions about what sort of reality could give rise to the quantum facts (5491).

There are four key experiments that describe the weirdness of quantum theory

The first is the double slit experiment If we shoot electrons toward a barrier with two slits, we would expect different outcomes if electrons act as particles or if they act as waves. There would be two bands if they act as particles, and multiple rows if they act as waves. In this case, the electrons act as waves would.

The second adds electron detectors at each slit. If electrons act as waves, both will go off at the same time when an electron is sent out. Otherwise, just one will activate at a time. In this case, the electrons act as particles would, and activate one detector at a time.

Experiment three uses a photon gun. Photons are fired through a beam splitter. If the photons act as a wave, the wave will split into two, reflect off of two mirrors, and then interfere with each other, not affecting photographic paper where the waves intersect. If they act as particles, there will be no interference- they will travel to one mirror or another, and hit the paper. In this experiment, photons act like waves.

Experiment four adds photon detectors between the mirror and the photographic paper. Here, either one detector goes off at a time, not both. This is as is expected if photons act as particles.

Regarding the math of QT, a few things distinguish it from other models. When using math to describe the motion of a falling boulder, it is non-controversial how each aspect of the equation (time, acceleration, etc.) match reality. QT makes extremely successful predictions, but a great deal of it is hard to match up with reality. It is also probabilistic instead of deterministic.

Interpretation of QT is where most of the controversy comes from. Interpretation is a largely philosophical matter that involves trying to figure out what reality must be like to give rise to the uncontroversial experimental results.

DeWitt breaks down multiple interpretations: including the standard or Copenhagen interpretation, which involves a collapse of the wave function on measurement, the Bohm interpretation, that adds faster than light communication but gets rid of the superposition, and the multiverse interpretation, that gets rid of the wave function collapse. Instead of the wave function collapsing on a single reality, reality continues to be branched out and superimposed, with many branches of reality existing at once.

Chapter 26: Quantum Theory and Locality- EPR, Bell’s Theorem, and the Aspect Experiment

A running question in quantum theory was whether or not a “local” view of reality is true, or a “non-local” one. As far as I can understand, the local view states that nothing can cause or affect another thing without some sort of contact or influence. We can generally say an affect is non-local it occurs faster than the speed of light. Since nothing should be able to do so, such an affect would be non-local.

The EPR/Bell/Aspect trio of experiments help establish a non-local view of reality. EPR is basically a thought experiment about what a non-local event would look like. Bell’s theorem is a way to actually test the assumption mathematically. The Aspect experiments further support the non-local view. The results that we would expect if reality is local do not occur- instead those in line with quantum theory and non-locality occur.

Chapter 27: Overview of the Theory of Evolution

Evolution can be reduced to two major points. It (basically) occurs when there is 1) variation and 2) a struggle for existence (a selection process). DeWitt contrasts this against myths of evolution. The most pervasive, he says, is that there is inherent teleology in evolution, sort of like the classic image of an animal steadily walking more upright until it becomes human. There is no built in goal of evolution. Second myth is that evolution works totally by chance. While chance is an important part, there is also the selection process, and generational changes. Briefly he confronts the idea that evolution is just a theory, and the factual belief that it says humans come from current apes.

There’s a decent exposition on the history of the idea, but I don’t know if it is all that necessary to the major points of the book.

Chapter 28: Philosophical and Conceptual Implications of Evolution

DeWitt first looks at religious implications of evolution. Some thinkers, like Dennett and Dawkins say that any Western Abrahamic God is basically falsified by evolution. There is nothing in the empirical data that would lead us to such a God.

Process theologians like Haught think that evolution elevates God. Instead of some sort of static creation that is made and done, there is a process of universal evolution that continues, instead of just ending abruptly after completion. DeWitt’s major point is that our overall worldviews are extremely important in distinguishing the two interpretations or reactions. Both of these camps fully accept the facts of evolution, but there are considerations that go beyond the facts.

Next DeWitt looks at how ethics may be affected by evolution. There’s some fairly interesting stuff here on game theory and the evolution of morality. But really I think the naturalistic fallacy makes it much harder to take such scientific findings and get to morality with them. Of course Haught thinks that somehow evolution grounds ethics, but it seems like mumbo jumbo to me. A more responsible thinker would describe why, but all I’ll say is that the is/ought gap remains, even through Haught’s thick philosophical cover.

Chapter 29: Worldviews- Concluding Thoughts

Summary of the whole thing.

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