What is mass?
The question seems very simple at first sight. But think very well before answering this. Can you really define mass, or specifically, inertial mass? I know for a fact that at the moment many scientists are finding it hard to properly define mass, and are currently arguing about it. It is hence a slightly controversial topic.
Many like to simply say mass is the amount of matter in a body. That is not the whole story though.
Is it enough to say that inertial mass is just a quantitative measure of an object’s reluctance to accelerate?
Einstein’s theory of special relativity has been thought to provide us with some extra insight as to what mass is, however it is not yet absolutely definite and has not changed our understanding of mass.
So in your opinion, what is mass?