What is theoretical physics?
What is theoretical physics?
The goal of physics is to understand the phenomena that surround us. More precisely, we try to extract laws governing cause-and-effect relationships. For example, if you lift an object and then let it go, it falls downward. Physics allows us to highlight laws that describe how the object falls, its trajectory, and the time it takes to fall.
To do this, physics uses theories. In the case of the example above, there are several theories of gravitation — notably Newtonian gravitation and General Relativity — which describe in different ways how bodies interact with one another.
We call theoretical physics the sub-discipline that creates and studies these theories. All theories are expressed in a mathematical language and use mathematical tools. The part of physics that focuses on the formal aspects is called mathematical physics.
How do we know if a theory is valid?
Why are there multiple theories to describe gravitation? Before answering that question, we should first be glad that at least one exists — because there are phenomena for which we still don’t have a satisfactory theory, and therefore don’t understand them!
Going back to gravitation: the Newtonian theory was proposed in the 16ᵗʰ century and allowed us to understand the trajectories of the planets around the Sun under the influence of its gravitational pull. However, certain phenomena appeared that this theory could not satisfactorily explain (for example, some anomalies in planetary motion). It was then necessary to look for another theory, which gave rise to General Relativity.
It is experimentation that ultimately allows us to decide between the different theories that may be proposed to describe phenomena.
And what about the LAPTh?
The scientific activities of the members of the LAPTh can be grouped into three major, interconnected themes:
- Mathematical physics
- Using particle physics theories to predict or understand experimental results: phenomenology
- Applying particle physics theories in the field of astrophysics: particle astrophysics.
LAPTh documents for popularization
Theoretical physics can be difficult to make accessible to the general public. Several presentations were developed collaboratively by a small group of researchers and research professors from the laboratory, with the aim of identifying the major conceptual challenges and maintaining the scientific rigor of the popularized explanations.
A daunting task indeed!
These presentations are then offered and delivered in various settings (high schools, science centers, science festivals, etc.) by several members of the group that created them.
Here are the visual materials for the three presentations developed, as well as the link to our YouTube page
Physics for Grandma
Starting with Einstein’s maxim, “You haven’t truly understood something until you can explain it to your grandmother,” our colleague François Arleo and his illustrator sister, Roxane, introduce us to physics in a very playful and artistic way. How do you explain particle physics to your grandmother who has no scientific background?
Through a series of wonderfully illustrated books, we progress step by step into the subatomic world… Three small books have already been published:
Through a series of wonderfully illustrated books, we progress step by step into the subatomic world… Four small books have already been published:
A Soup Called Quark-Gluon Plasma
A Special Zoo
Particle Physics Runs Smoothly
SuperGaston, an Ultra-High Energy Cosmic Ray
In addition to these booklets, presentations are also regularly given in high schools and community centers.
To learn more, visit the “Physics for Grandma” page: http://physiquepourgrandma.blogspot.com
Antimatter
The word “antimatter” is surrounded by a certain aura of mystery and raises many questions for those curious about science. Richard Taillet has dedicated a feature to this topic on the Futura-Sciences portal futura-sciences.
