For those of you familiar with Special Relativity, it's an exercise in imagination and science. That a thought experiment can reveal much about reality suggests that mind is more than a fundamental tool in arriving at conclusions, but has the power to influence reality. What was once previously believed to be two separate domains have now been blended by metaphysics.
The beginnings of a metaphysics have now been firmly established for mankind over the last 35 years. Yes, the laws of Physics are invariant in all inertial frames of reference. Light remains fixed to all observers.
It certainly stirs the imagination.
One interesting thing about light/energy, the speed of light, and Special Relativity SR, is SR says that an object in motion, with velocity=V, as it approaches the speed light; c, will increasingly show space and time contracting/slowing.
On the other hand, a photon of energy, which travels at the speed of light, can retains a variety of finite fixed wavelengths/colors and these wavelengths do not all contract to a common wavelength, even while moving at the speed of light. How can light retain a wide range of finite frequencies; red, blue, x-rays, when the speed of light and SR, implies all should merge to uniformity due to max time dilation?
This is a trick question, but it gives some added insight into Special Relativity, less explored. One way to explain this is all the examples we use for Special Relativity, involve material objects with mass; twins and clocks. Photons are energy and not mass. My conclusion is mass is needed for Special Relativity effects. Einstein included a calculation for relativistic mass, with photons not having this relativistic mass to influence its space and time attributes of wavelength and frequency. They do not get the same changes.
Some metaphysics appears to come from some in Physics, who want to explain away relativistic mass, as not being real, but more of a function of space and time; distance and time. But the photon shows mass or not mass makes a big difference in SR.
Mass is the capacitance behind space-time. The mass of our sun creates a sustained zone of alter space-time; with capacitance. In General Relativity; GR, the more mass we add the greater the GR effect on space-time. In the case of SR, velocity adds relativistic mass to the rest mass, and this relativistic mass gives a space-time altering effect similar to adding more mass in GR. The difference is although SR can curve space and time, its does not add gravity. Only the rest mass can do that.
I never heard of a SR scenario, of the moving twin in the rocket coming back compressed to a tiny cube, implicit of his relativistic mass adding gravity and squashing his rocket into a black hole. Instead his frame of reference appears to be the same, based on rest mass, but all the other magic occurs in terms of him aging slower via the tug of relativistic mass on time and space.