Far out cosmology: why no GUTS? (Introduction)

by David Turell , Sunday, April 09, 2017, 18:44 (2783 days ago) @ David Turell

A scholarly review of the problem:

http://nautil.us//blog/the-quest-for-unity-is-not-something-physics-is-cut-out-to-do?ut...

"In physics, we like theories that are simple and broad-ranging. By “simple,” physicists usually mean a mathematical theory that rests on as few postulates as possible; by “broad-ranging,” we mean theories that can describe a wide class of phenomena, even when apparently not related. A quintessential example is Einstein’s theory of general relativity. Resting on a handful of simple principles, it successfully describes planetary orbits in this (and any) solar system, black holes, gravitational waves, and the expansion of the universe.

***

"beautiful theories have a mathematical integrity that seems to be revealing something deep about nature, a sort of hidden code of Creation: From the very large to the very small, the universe has many layers, each built upon its own mathematical description. Are these not parts of a larger composition, a single unifying tune resonating through all of nature?

***

" But today we are seeing the limits of this Platonic thrust to mathematize nature, due to a lack of experimental validation and several theoretical obstacles—including the possibility of multiple universes and the troubling questions they pose.

"The modern version of the unifying quest is string theory, which supposes that the fundamental entities in nature are vibrating tubes of energy instead of point-like particles of matter.

***

"Fast-forward three decades, and the scenario has changed dramatically. Physicists were shocked to find, instead of a single solution, a huge number of solutions—by some estimates, a 1 followed by 500 zeros, each a different twist in the extra-dimensional space, each generating a different universe. Presumably, each one of these has its own set of fundamental constants, numbers such as the electron’s mass and charge and the strength of the gravitational attraction, which determine nature’s physical properties. Where’s our universe among such vast number of possibilities? We do know that if we tweaked such constants by very small amounts, life wouldn’t be possible: We wouldn’t be here. In other words, we live where we live because we couldn’t live anywhere else—our universe is one of the few that allows for our existence. True enough, but as a scientific argument this buys us very little. Worse, it sounds tautological. String theory went from being the theory that would mathematically prove the uniqueness of our universe to a theory that allows a countless number of possible universes, none more compelling than the other.

***

"The problem is rooted in a much deeper philosophical issue, that of the First Cause. Being creatures immersed in the passage of time, with a clear beginning and an end, humans have been forever dumbfounded by initial conditions. How could something come out of nothing? And what sets the properties of this something (read “values of fundamental constants”) at the beginning? Who ordered that? Who ordered us?"

Our mistake is that, within a scientific context, these are the wrong questions to ask.

Physics works under a very clear framework. In order to determine the time evolution of a system, we need to state its initial conditions, the state of the system at time zero. This implies knowledge of the system at the beginning, something we obtain through measurement. In cosmology, that becomes impossible. We may restrict the initial conditions and the values of the fundamental constants given what we know about the universe today, but we can’t be sure that our conclusions are in any way final. The clues we gather today about the universe’s distant past can only give us a fragmented picture of what happened. The multiverse only pushes the issue of initial conditions to a higher level, without solving it.

***

" Maybe our current dilemma is a symptom of something bigger, a deep change in the methodological nature of physical theories. We may have to see them historically, tossing aside First Cause explanations and timeless truths as fruitless pursuits. Quite possibly, the nature of physical theories mirrors their own narrative construction, piecewise and gradual, creations of our imperfect and incomplete grasp on physical reality. And there’s nothing wrong with that."

Comment: One simple solution is to accept God as the First Cause. String theory is obviously dead snd no other is apparently on the way.