One key piece to understanding how quantum gravity affects low-energy physics is the concept of an effective field theory (EFT). An EFT is a theoretical framework that describes the behavior of a physical system at low energies, even though the underlying theory may be more complicated and involve higher energy scales. In the context of quantum gravity, an EFT can be used to describe the effects of quantum gravity on low-energy phenomena, such as the behavior of matter and fields in the universe.

By constructing an EFT, physicists can make predictions about how quantum gravity might affect low-energy physics without having to solve the full theory of quantum gravity, which remains a challenging problem. The EFT approach involves identifying the relevant degrees of freedom and symmetries at low energies and building a simplified theory that captures the essential features of quantum gravity's influence.

One example of an EFT in quantum gravity is the Standard Model Effective Field Theory (SMEFT), which extends the Standard Model of particle physics to include higher-dimensional operators that arise from quantum gravity effects. The SMEFT allows physicists to study the potential modifications to the Standard Model due to quantum gravity, such as tiny deviations in the properties of particles and interactions.

Another important aspect of understanding how quantum gravity affects low-energy physics is the concept of renormalization. Renormalization is a mathematical procedure used to remove infinities that arise in quantum field theory, including quantum gravity theories. By applying renormalization techniques, physicists can make sense of the theory's predictions and extract finite and meaningful results at low energies.

Furthermore, the study of black holes and their properties provides valuable insights into the connection between quantum gravity and low-energy physics. Black holes are fascinating objects that exhibit extreme gravitational effects and are predicted to be the key arena where quantum gravity becomes significant. By investigating the thermodynamics and behavior of black holes, physicists can gain clues about the underlying quantum nature of gravity and its impact on low-energy phenomena.

In summary, understanding how quantum gravity affects low-energy physics involves developing effective field theories, employing renormalization techniques, examining black hole physics, and exploring other theoretical approaches that bridge the gap between high-energy quantum gravity and low-energy phenomena accessible to current observations and experiments.