What are the differences between Newton's and Einstein's theories?
Answers
Answer:
In the 17th century Newton concluded that objects fall because they are pulled by Earth's gravity. Einstein's interpretation was that these objects do not fall. According to Einstein, these objects and Earth just freely move in a curved spacetime and this curvature is induced by mass and energy of these objects
Answer:
Newton's Theory
Newton's law of universal gravitation is usually stated as that every particle attracts every other particle in the universe with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.
Einstein's Theory
The theory of relativity usually encompasses two interrelated theories by Albert Einstein: special relativity and general relativity. Special relativity applies to all physical phenomena in the absence of gravity. General relativity explains the law of gravitation and its relation to other forces of nature.
The Difference
In the 17th century Newton concluded that objects fall because they are pulled by Earth's gravity. Einstein's interpretation was that these objects do not fall. According to Einstein, these objects and Earth just freely move in a curved spacetime and this curvature is induced by mass and energy of these objects.
Brief Explanation
One area where Einstein’s theories differ from Newton’s is in the Laws of Motion. Newton tells us that an object’s velocity changes directly in proportion to an applied force (F=ma aka F=∂p/∂t). Einstein comes along and complicates things as we approach the speed of light, forcing us to take relativity (relativistic mass and time dilation) into account. Since most of us will never approach the speed of light in our daily movements, Newton’s approach works great. But start experimenting in a particle accelerator, and you can’t live without Einstein’s adjustments.
Similarly, Newton’s Law of Universal Gravitation assumes objects have constant mass. But approaching the speed of light, Newton’s famous and simple equation (g = G m1 m2 / d^2) gets confounded with relativistic mass.
In Newton’s day it would never have been questioned that time flows at a constant rate, regardless of an observer’s frame of reference. (In fact, most didn’t question it in Einstein’s day either.) But, you guessed it, as you approach the speed of light you’ll find that time actually flows at a different rate (aka, time dilation).
Another aspect of “Newtonian Physics” that gets adjusted thanks to Einstein (and his peers) are the Law of Conservation of Energy (energy can neither be created nor destroyed) and the Law of Conservation of Mass (mass/matter can neither be created nor destroyed). Thanks to Einstein’s mass-energy equivalence (E=mc^2) we know that mass can be destroyed, and energy created, in a nuclear reaction. So now we have the Law of Conservation of Mass-Energy (e.g., mass and/or energy can neither be created nor destroyed by ordinary physical and chemical means) – although even this can get confounded under certain circumstances with very precise measurements.
In addition to Einstein’s work, several other modern scientific theories diverge from Newton’s. In general you might summarize the differences as having to do with the very-small (quantum effects) and/or very-fast (relativistic effects).
Note: This are collected from various pages. I just tried to make it easy.