Quantum Spectacles

All physical laws are expressed in terms of differential equations in space and time that require initial data to predict the evolution of whatever system we are considering. In classical physics we have Newton’s laws, Maxwell’s equations and the Newton’s law of gravitation, which are all second order differential equations in time.  At the quantum level we either speak in terms of Schrodinger’s equation – a first order equation in time – or in terms of propagators that propagate wave-functions forward in time. Relativity mixes time and space and makes gravity a theory of geometry of space-time, thus the fundamental equation of general theory of relativity relates geometry of a space-time to its energy-matter content. However, we most often solve it as an initial value problem. After the space-time, along with its geometry has been obtained, it provides the causal structure that everything else in the universe must abide by. The essential point here is that physics deals mainly with cause and effect.  This is built into the scientific method where we pose questions in terms of experiments that lead to certain results that we then explain in terms of laws of physics.  

It seems that the question of the prime mover or the first cause (that itself is uncaused) cannot be formulated in terms of the current structure of physical laws. Is that absolutely true? General relativity predicts that most space-times become singular either in past or in the future, especially the one that we are supposed to be living in. In some sense this singularity removes the problem of initial data since all future states lead back to the same singular state. However, the popular thinking is that the singular event that we call the big-bang, cannot be described in terms of classical physics, primarily due to the mathematical singularity that exists at the big-bang that we believe to be unphysical. It is possible that quantum physics will resolve this singularity? What do we hope to find in such a theory? Shall we find that the Universe tunnels into another phase? Would the structure of that phase still be causal? We don’t know the answers to these question yet.

But perhaps causal laws are not the final truths of Nature? The Universe could also very well exist forever in time, but that too would not explain why it is there in the first place. Thus, steady state cosmology, although it avoids the big-bang, is not necessarily philosophically more appealing, though this is usually stated by its proponents. A philosophically satisfactory universe would be the one that creates itself out of nothing, with all the stuff like matter and energy and laws that govern them built into it. Can differential equations describe such a theory? There are differential equations that in certain cases do not necessarily require initial conditions: these are the so called non-linear equations. However, a resolution of this fundamental problem cannot lie in the absence of initial conditions alone but rather in some sort of package that makes our Universe logically imperative. Although, even then we could question why there should be anything like logic that exists separately. Perhaps we haven’t yet developed the language required to understand why there is something rather than nothing!  

PS: This post has been reworked from this original post.