Monday, July 26, 2010

Newton - A "Relative" of Einstein

While answering the query of a school kid recently pertaining to the Law of gravitation, I started thinking a bit more about Newtons laws of motion. One thing led to another and a thought experiment now seems to suggest to me that Newton may have unknowingly laid down the foundation for the Special Theory of Relativy in some sense. This is a very crude comparison in some senses but nevertheless it seems interesting (well to me atleast :-))
Here is what I have come up with.
We all know that Newtons law says that F=ma i.e The force is equal to the product of the mass and the acceleration of a body. Viewed in terms of an objects relation to the force of gravity, this also leads to the definition of "Weight" which is w = mg and here g being the acceleration due to gravity.
In essense thus, the acceleration of a body can be thought of as contributing to its weight. Acceleration on the other hand implies an addition of energy to the system. Thus, adding energy to a body by accelerating it in some sense increases the weight of the body and hence necessitates addition of higher amounts of energy to maintain the acceleration. This is also refelected by the Inertia of Motion exhibited by a body.
Looking at this from a different viewpoint, it appears that the addition of energy to a system and trying to increase its acceleration will in some respect manifest as an increased weight of the system. (E=mc2.. wink :-) )
So the next logical qusestion would be what the limiting condition is i.e how much energy can be added to the system so that its weight (mass) becomes so large that no amount of energy can accelerate it further. What Einstein found is this limit and gave us the exact relation between mass and energy.

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