You gave an example in the lecture "length contraction" that in case of a train moving through a tunnel the height of both the train and the tunnel will remain fixed otherwise the train can't pass through the tunnel.Isn't it a same kind of paradox like this?(i.e. both the train and tunnels perspective are equally correct?)

Couple of more thoughts. Let say there is a single door barn with a solid back wall stopping the arriving pole. Just before the pole stops inside the barn Gracie doesn’t see the pole as it is completely inside the barn. As it decelerates the 5 ft back end reverses out of the barn. At the deceleration George notices that the door side of the barn extends forward hiding part of the pole. Both the barn and pole have momentum (depending from point of view) as both are returned to the original formation? On the other hand the masses and densities are huge. So even after the pole or barn stops the infinite gravity has already collapsed one of them into a black hole. George can argue the barn has self destructed as a black hole and Gracie says the pole is converted into a black hole.

In a sense I see the Relativity of Simultaneity as being an example of Quantum Superposition in the Macroscopic world.

As the Earth rotates on its axis, it hurtles us through space at nearly 1700 km/hr for someone on the equator. It’s estimated that our Sun’s speed is around 200–220 km/s. Both are in motion. The earth is in the solar system barn, the sun in the Milky Way barn.