Write and explain Einstein's theory of special relativity in the context of mass-energy equivalence.

(N/A) According to Einstein's theory of special relativity,mass is considered another form of energy.
Before this theory,it was assumed that mass and energy were conserved separately in any physical reaction.
Einstein demonstrated that mass is equivalent to energy and can be converted into other forms of energy,such as kinetic energy,and vice versa.
This mass-energy equivalence is expressed by the equation $E = mc^2$,where $m$ is the mass and $c$ is the velocity of light in a vacuum,approximately $3 \times 10^8 \ m/s$.
Experimental verification of this relation has been achieved through the study of nuclear reactions involving nucleons,nuclei,electrons,and other subatomic particles.
In such reactions,the law of conservation of energy states that the total initial energy must equal the total final energy,accounting for the mass-energy conversion.
This concept is fundamental for understanding nuclear binding energy,nuclear masses,and the interactions between nuclei.