The Universe never ceases to amaze us and pose questions. The nature of gravity holds a central place in current research.
In 2009, theoretical physicist Erik Verlinde proposed an innovative view of gravity. According to him, this fundamental force that we are well acquainted with might be the emergence of hidden processes, an idea that, 15 years later, continues to fuel scientific debate without yet having found strong experimental confirmation.
The concept of emergence is not new in physics. It explains how complex properties can arise from the simple interaction of numerous components. For example, the temperature of a gas is not an intrinsic property but results from microscopic collisions between its molecules. This approach is at the heart of statistical mechanics, a branch of physics that builds bridges between microscopic behaviors and emergent properties.
Verlinde was inspired by the work of Stephen Hawking and Jacob Bekenstein on black holes in the 1970s, which showed that their properties could be described by the laws of thermodynamics. He proposed that gravity could be an emergent property, stemming from deep and unknown physical processes, using the tools of statistical mechanics.
In 2016, Verlinde's idea took a new turn with the proposal that the Universe, by containing dark energy, develops a new emergent property of space itself, which contracts in low-density regions. This perspective offers an alternative to dark matter, this invisible substance that represents the majority of the mass of galaxies according to current models, yet remains undetected directly.
The theory of emergent gravity allows for the testing of new ideas on the structure and evolution of galaxies, differentiating its predictions from those based on dark matter. However, experimental results are mixed. Some preliminary tests have favored emergent gravity, but more recent observations have not confirmed this advantage.
Research on emergent gravity is not finished. The theory is still young, relies on many assumptions, and requires more rigorous testing, such as exploiting data from the cosmic microwave background. If proven correct, our understanding of the Universe, gravity, motion, and even time and space, will have to be radically rethought from the perspective of emergence. For now, it's an idea that awaits further exploration.