| dc.description.abstract | The formulations of the theories of special and general relativity and of the theory
of quantum mechanics in the first decades of the twentieth century are a fundamental
milestone in science, not only for their profound implications in physics but
also for the research methodology. In the same way, the courses of special and
general relativity and of quantum mechanics represent an important milestone for
every student of physics. These courses introduce a different approach to investigate
physical phenomena, and students need some time to digest such a radical change.
In Newtonian mechanics and in Maxwell’s theory of electrodynamics, the
approach is quite empirical and natural. First, we infer a few fundamental laws from
observations (e.g., Newton’s Laws) and then we construct the whole theory (e.g.,
Newtonian mechanics). In modern physics, starting from special and general relativity
and quantum mechanics, this approach may not be always possible.
Observations and formulation of the theory may change order. This is because we
may not have direct access to the basic laws governing a certain physical phenomenon.
In such a case, we can formulate a number of theories, or we can
introduce a number of ansatzes to explain a specific physical phenomenon within a
certain theory if we already have the theory, and then we compare the predictions
of the different solutions to check which one, if any, is consistent with observations.
For example, Newton’s First, Second, and Third Laws can be directly inferred
from experiments. Einstein’s equations are instead obtained by imposing some
“reasonable” requirements and they are then confirmed by comparing their predictions
with the results of experiments. In modern physics, it is common that
theorists develop theoretical models on the basis of “guesses” (motivated by theoretical
arguments but without any experimental support), with the hope that it is
possible to find predictions that can later be tested by experiments. | en_US |
