Compare Einstein and Newton's pictures of gravity.
Einstein and Newton both had different understandings and explanations of gravity.
Sir Isaac Newton's theory of gravity, which he published in 1687 in his famous work "Philosophiæ Naturalis Principia Mathematica," described gravity as a force that attracts two objects with mass towards each other. According to Newton, this force was instantaneous, acting at a distance, and could be measured using his law of universal gravitation. His theory successfully explained the motion of objects on Earth and in space, and it formed the basis of classical physics for over two centuries.
On the other hand, Albert Einstein's theory of gravity, known as General Relativity, was published in 1915. Unlike Newton's theory, Einstein's theory of gravity conceptualized gravity not as a force, but as a curvature of space and time caused by mass and energy. According to Einstein, objects with mass or energy create a curvature in the fabric of spacetime, and other objects move along the curved paths dictated by this curvature. This curvature is what we perceive as the force of gravity.
To visually compare Einstein and Newton's pictures of gravity, consider the following analogy:
Imagine a flat bedsheet representing spacetime. In Newton's picture, objects with mass would be like weights placed on the bedsheet. These weights would create a depression or dip in the sheet, and other objects would roll or fall towards the center of the depression. This is similar to Newton's concept of gravity, where objects are pulled towards each other due to a force.
In Einstein's picture, objects with mass or energy would be like a heavy ball placed on the bedsheet. Instead of creating a simple depression or dip, the ball would actually cause the entire sheet to curve around it. Now, if you were to roll a smaller ball near the heavy ball, it would naturally roll towards the heavy ball, not because of any force or pull, but because it is simply following the curvature of the sheet caused by the heavy ball.
In summary, Newton's picture of gravity involves the concept of a force acting at a distance, while Einstein's picture of gravity involves the concept of the curvature of spacetime caused by mass and energy. These two theories provide different explanations of how gravity works, and while Newton's theory is still highly accurate in many situations, Einstein's theory of General Relativity provides a more comprehensive and accurate description of gravity, especially in extreme conditions.