The mystery of being:
This book is an effort to understand why the universe the way it is, rather than the traditional question- how does the universe behave? It tries to answer the following three profound questions:
- Why is there something rather than nothing?
- Why do we exist?
- Why this particular set of laws and not some other?
These questions are traditionally dealt in philosophy. With the recent development in theoretical physics we are, as the author's belief, in a better position to answer these questions than before. Its time that we consider these questions again. As they say
Most of us do not spend most of our time worrying about these questions, but almost all of us worry about them some of the time.
The rule of law:
This chapter deals with the nature of physical laws. If nature is governed by physical laws three questions arise:
- What is the origin of the laws?
- Are there any exceptions to the laws, i.e., miracles?
- Is there only one set of possible laws?
The first two questions are taken up in the spirit of scientific determinism. The universe is a collection of large number of object which interact with each other following a specific set of laws and there are no exceptions to these set of laws. The first and the third question answered in later chapters . As to scientific determinism: given the state of universe at one time, a complete set of laws fully determines both the future and the past, the question of free will is discussed.
Do people have free will?
Do blue-green algae or bacteria have free will?
Descartes believed that human mind is different from the physical body and the laws of physics do not apply to the mind. We consist of two entities a body (which obeys physical laws) and a mind (or soul which has a free will). The authors take a different stand and assert that human behavi0ur is indeed determined by the physical laws. It is just that it not practical to define an initial state which takes into account all the trillions of molecules and compute their evolution with time in accordance with laws. So we adopt an effective theory, which is a framework created to model certain observed phenomena without describing in detail all the underlying process. Since we cannot solve the equations that determine our behaviour, we use an effective theory that people have free will.
What is reality?
The basic idea of this chapter is: there is no picture- or theory independent concept of reality. It adapts the viewpoint of model dependent realism: the idea that a physical theory or world picture is a model ( generally of a mathematical nature) and a set of rules that connect the elements of the model to observations.
Model dependent realism removes the idea of "reality" as more than one model may be consistent with the given observations. In that case both are equally valid models are reality and none is preferred. A model can have elements which may not be observables like quarks int the standard model. We don't ask the question whether quarks really exist. All we say is that the quarks exist in a model which so far agrees with the observations. As to characteristics of a good model is that it:
- is elegant
- contains few arbitrary of adjustable elements
- agrees with and explains all existing observations
- makes predictions about future observations that can disprove of falsify the model if they are not borne out.
Alternative Histories
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