Einstein did make statements regarding gravity, but his views on dark matter were different from our modern understanding. Here's a brief overview:
Gravity: Einstein's theory of general relativity revolutionized our understanding of gravity. According to general relativity, gravity is not a force acting between objects but rather the result of the curvature of spacetime caused by the presence of mass and energy. Einstein described this curvature as the interaction between matter (or energy) and the geometry of spacetime. His theory provided a new framework for understanding the behavior of gravity, including the motion of celestial bodies, the bending of light, and the expansion of the universe.
Dark Matter: The concept of dark matter emerged later, well after Einstein's time. Dark matter refers to hypothetical matter that does not interact with light or other forms of electromagnetic radiation, making it difficult to detect directly. Its existence is inferred from its gravitational effects on visible matter and the large-scale structure of the universe. Einstein did not specifically address the idea of dark matter in his work on general relativity. In fact, in 1933, he proposed an alternative explanation for the observed motion of galaxies that did not require the presence of dark matter. This idea, known as Einstein's "cosmological constant" or "lambda," suggested that a repulsive force could counteract gravity on large scales. However, later observations and measurements provided evidence in favor of the existence of dark matter, and the cosmological constant is now understood to represent the energy of empty space (dark energy) rather than dark matter.
It's important to note that our understanding of gravity and dark matter has evolved significantly since Einstein's time. While his theory of general relativity remains the foundation of our current understanding of gravity, the existence and properties of dark matter are still active areas of research and investigation in modern physics.