I thought it fitting, and indeed maybe even helpful, to give some examples (not too many, nor too technical) of how fine-tuning is discussed in physics literature:
“Fine tuning appears in many areas of particle physics and cosmology, such as the standard model (SM) hierarchy problem and the cosmological constant problem. These problems imply that the Universe we live in is a very atypical scenario of the theories we use to describe it."
Athron, P., & Miller, D. J. (2007). New measure of fine tuning. Physical Review D, 76(7), 075010.
“In pre-big-bang inflation the end of the inflationary era is fixed, while its beginning is delayed by curvature. Too much curvature — of either sign — shortens the duration of the inflationary era to the point that the flatness and horizon problems are not solved. Thus, in the absence of a mechanism that would naturally cause a large region of space to materialize with tiny curvature, pre-big-bang inflation requires fine-tuning of initial conditions to solve these cosmological problems. This makes it less robust, and therefore less attractive as an implementation of the inflationary paradigm.”
Turner, M. S., & Weinberg, E. J. (1997). Pre-big-bang inflation requires fine-tuning. Physical Review D, 56(8), 4604.
“This Lorentz violation can be removed by explicit Lorentz-violating counterterms of dimension 4 in the Lagrangian that are fine tuned to give the observed low-energy Lorentz invariance. But such fine tuning is unacceptable in a fundamental theory.”
Collins, J., Perez, A., Sudarsky, D., Urrutia, L., & Vucetich, H. (2004). Lorentz invariance and quantum gravity: an additional fine-tuning problem?. Physical review letters, 93(19), 191301.
"The universe is said to be extraordinarily ‘fine-tuned’ for life. The inhabitability of our universe depends on the precise adjustment of what seem to be arbitrary, contingent features. Had the boundary conditions in the initial seconds of the big bang, and the values of various fundamental constants differed ever so slightly we would not have had anything like a stable universe in which life could evolve. In the space of possible outcomes of a big bang, only the tiniest region consists of universes capable of sustaining life. Most either last only a few seconds, or contain no stable elements or consist of nothing but black holes. This is a fairly standard story told by cosmologists—there is some controversy, concerning for instance the appropriate measure on the space of possible outcomes—but I will assume it is the right picture for the purpose of this discussion.2 The situation is thought to be something like the following. Nuclear bombs are connected to a high security combination lock, such that dozens of dials have to be adjusted with extreme precision to avoid detonating the bombs. Had any one dial differed ever so slightly from its actual position, the world would have been destroyed. In the absence of an explanation of why the dials were adjusted as they were ~suppose they had been spun at random! we would find it astonishing that we were here to consider the matter."
White, R. (2000). Fine‐Tuning and Multiple Universes. Nous, 34(2), 260-276.
“Fine-tuning does exist as a characteristic of our current physical and cosmological models. There are free parameters remaining theoretically unexplained. We can give them any value, and they remain compatible with the theory. To choose the right values, we make experiments or observations and fill them in in the model. Finding other ways to deduce those values is still a major problem in modern physics (Smolin 2006, 13). Furthermore, many of these parameters are sensitive to slight changes, which have important consequences for the evolution of the universe. It is in that sense that we can say that they are fine-tuned. The open question is not whether there is fine-tuning, but whether we will be able in the future to explain all these parameters from a more fundamental theory.”
Vidal, C. (2012). Fine-tuning, quantum mechanics and cosmological artificial selection. Foundations of Science, 17(1), 29-38.
“Fine tuning appears in many areas of particle physics and cosmology, such as the standard model (SM) hierarchy problem and the cosmological constant problem. These problems imply that the Universe we live in is a very atypical scenario of the theories we use to describe it."
Athron, P., & Miller, D. J. (2007). New measure of fine tuning. Physical Review D, 76(7), 075010.
“In pre-big-bang inflation the end of the inflationary era is fixed, while its beginning is delayed by curvature. Too much curvature — of either sign — shortens the duration of the inflationary era to the point that the flatness and horizon problems are not solved. Thus, in the absence of a mechanism that would naturally cause a large region of space to materialize with tiny curvature, pre-big-bang inflation requires fine-tuning of initial conditions to solve these cosmological problems. This makes it less robust, and therefore less attractive as an implementation of the inflationary paradigm.”
Turner, M. S., & Weinberg, E. J. (1997). Pre-big-bang inflation requires fine-tuning. Physical Review D, 56(8), 4604.
“This Lorentz violation can be removed by explicit Lorentz-violating counterterms of dimension 4 in the Lagrangian that are fine tuned to give the observed low-energy Lorentz invariance. But such fine tuning is unacceptable in a fundamental theory.”
Collins, J., Perez, A., Sudarsky, D., Urrutia, L., & Vucetich, H. (2004). Lorentz invariance and quantum gravity: an additional fine-tuning problem?. Physical review letters, 93(19), 191301.
"The universe is said to be extraordinarily ‘fine-tuned’ for life. The inhabitability of our universe depends on the precise adjustment of what seem to be arbitrary, contingent features. Had the boundary conditions in the initial seconds of the big bang, and the values of various fundamental constants differed ever so slightly we would not have had anything like a stable universe in which life could evolve. In the space of possible outcomes of a big bang, only the tiniest region consists of universes capable of sustaining life. Most either last only a few seconds, or contain no stable elements or consist of nothing but black holes. This is a fairly standard story told by cosmologists—there is some controversy, concerning for instance the appropriate measure on the space of possible outcomes—but I will assume it is the right picture for the purpose of this discussion.2 The situation is thought to be something like the following. Nuclear bombs are connected to a high security combination lock, such that dozens of dials have to be adjusted with extreme precision to avoid detonating the bombs. Had any one dial differed ever so slightly from its actual position, the world would have been destroyed. In the absence of an explanation of why the dials were adjusted as they were ~suppose they had been spun at random! we would find it astonishing that we were here to consider the matter."
White, R. (2000). Fine‐Tuning and Multiple Universes. Nous, 34(2), 260-276.
“Fine-tuning does exist as a characteristic of our current physical and cosmological models. There are free parameters remaining theoretically unexplained. We can give them any value, and they remain compatible with the theory. To choose the right values, we make experiments or observations and fill them in in the model. Finding other ways to deduce those values is still a major problem in modern physics (Smolin 2006, 13). Furthermore, many of these parameters are sensitive to slight changes, which have important consequences for the evolution of the universe. It is in that sense that we can say that they are fine-tuned. The open question is not whether there is fine-tuning, but whether we will be able in the future to explain all these parameters from a more fundamental theory.”
Vidal, C. (2012). Fine-tuning, quantum mechanics and cosmological artificial selection. Foundations of Science, 17(1), 29-38.
