Albert Einstein did not disprove or change Isaac Newton's laws of motion and gravity. Instead, Einstein's theory of relativity, specifically his general theory of relativity, provided a deeper and more comprehensive understanding of the laws of motion and gravity.
Newton's laws of motion, published in his work "Mathematical Principles of Natural Philosophy" in 1687, described the behavior of objects in classical mechanics. These laws are still valid and applicable for most everyday situations. They include:
Newton's First Law (Law of Inertia): An object at rest tends to stay at rest, and an object in motion tends to stay in motion unless acted upon by an external force.
Newton's Second Law (Law of Acceleration): The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. This law is commonly expressed as the equation F = ma, where F is the net force, m is the mass of the object, and a is its acceleration.
Newton's Third Law (Law of Action and Reaction): For every action, there is an equal and opposite reaction.
Newton also formulated the law of universal gravitation, which describes the force of attraction between two objects with mass. According to Newton's law of gravitation, the force of attraction between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. This law is mathematically expressed as F = G * (m1 * m2) / r^2, where F is the force of gravity, G is the gravitational constant, m1 and m2 are the masses of the objects, and r is the distance between their centers.
Einstein's theory of relativity, developed in the early 20th century, provided a new framework for understanding the laws of motion and gravity in extreme conditions and at high speeds. Einstein's theory introduced several significant changes and expansions to our understanding:
Relativity of Simultaneity: Einstein's theory of relativity challenged the concept of absolute time and introduced the idea that the simultaneity of events can be relative to the observer's reference frame.
Time Dilation: According to Einstein's theory, time can be dilated or stretched depending on the relative velocity of observers. This means that time can appear to pass differently for different observers.
Length Contraction: Einstein's theory also introduced the concept of length contraction, which states that the length of an object in motion appears shorter when measured by an observer in a different reference frame.
Equivalence Principle: Einstein's general theory of relativity replaced Newton's law of gravitation with a new understanding of gravity as the curvature of spacetime caused by mass and energy. The equivalence principle states that the effects of gravity are indistinguishable from the effects of acceleration.
Einstein's theory of relativity does not invalidate Newton's laws of motion and gravity. Instead, it extends our understanding of these laws in situations involving high speeds, strong gravitational fields, and extreme conditions. Newton's laws of motion and gravity remain accurate and useful for most everyday scenarios, while Einstein's theory of relativity provides a more complete description of the universe at large scales and in extreme circumstances.