Of course not. It is theoretically and experimentally proven to the bone.
c^2 is definitely not a speed. ‘c’ denotes the speed of light, so its dimension in SI unities is ‘m/s’. So c^2 would be (m/s)^2. What would that be?
There is no "it’s light speed’. The speed of light is a universal invariant. And pure energy or pure mass has no meaning: it is always the energy or mass of something.
What does that even mean??
More nonsense. To be exact, light speed is not just the speed of light, it is the maximum speed of causality. All massless particles can only travel at this fixed speed. So light cannot ‘approach’ light speed, it has physically necessarily this speed.
No, it is about how to transform physical parameters (lengths, time, momentum, energy, electrical fields etc) from one inertial frame to another, and on what invariants observers in different inertial frames agree upon.
And nonsense again.
What E = mc^2 really means is that when a material object loses energy, it also loses mass, or when it gains energy its mass increases. A full electrical battery is more heavily than an empty one; a stretched string has more mass than a relaxed one; a hot cup of tea has more mass than a cold one; a U-235 nucleus has more mass than its fission products, etc. It is just so that the strong nuclear force is the strongest force in nature, so the biggest energies are involved. But E = mc^2 applies to all physical processes.
So no, write4u, there is no special mechanism for E = mc^2. In the explosion of dynamite there is also a mass loss, it is only much smaller than by nuclear processes.
Obviously it isn’t. Not at all.
No. It says that a part of the mass of the nuclei is converted to energy, i.e. kinetic energy and radiation.