Is Time a Dimension? Can there be a Time Travel?

How many people claim to understand Special Relativity and General Relativity? Is Time a Dimension? Can there be a Time Travel?

My opinion is that Time is not a Dimension but an artifact of "ticks" inherent in the dynamic nature - hence parametric. There is nothing like Time Travel as Time is not a Dimension and even if it was, we have to "destroy" ourselves when going past our births.

SR artifacts come about because of the need to synchronize Time in all Frames of References (only man wants to measure everything and Nature has a different way through cause and effects of its Laws), and use of Light or EMF to signal between References. The speed of Light/EMF is limited and hence it causes Time and Space dilation/contraction/expansion etc.

GR accounts for an Accelerating Reference to accommodate Gravity. Here the Cartesian Co-ordinates are abandoned, and so are the single order Derivatives to account for the unit vectors in the 3D Space or 4D Space-Time. To accommodate Gravity, the Bent Co-ordinates like Ellipsoid or BiPolar Co-Ordinates are taken, which have higher order (cross) derivatives to "bent" the co-ordinate lines. These are called Tensors (first developed to study Stress and Shear). And then Einstein goes on to say, the mass causes Space-Time Fabric curvature and hence the cause of Gravity. Example given is a rubber sheet with 2D lines and a mass sinking the 2D lines - and Rubber Fabric. Here it is implied that some mass is being pulled down by some force, which is again gravity. This is just a bad artifact of the example. How can gravity cause curvature, and how can mass cause curvature causing gravity at the same time? The idea was to communicate the "bent" of the 2D (or 4D Space-Time) lines. This was a smoke and mirror answer to Gravity. Yes in Nature, the cause and effect could be a two way street. So then the example make a perfect sense.

So why SR and GR are right? Because we use Light to propagate the Time and Space "signals". Why does GR come true? Because Einstein believed in Ether and its the "varying density" of the field lines of Ether - and not Space-Time Fabric - but it does change the dS/dT slopes or Space-Time Relationship (a varying Ether field would do the same - go from Cartesian Co-Ordinate like field to "bent" co-ordinates like field).

Quantum Physics and Relativity have dichotomy. Then why does Atomic Clocks listen to GR in gravity field?

I want to take this opportunity to learn more about this from people who know more than me - and experts on the subject.

It is said SR and GR were not understood by Scientists for a long time.

The Principle of Invariant Light Speed

It took me 38 years to understand this - why 'The Principle of Invariant Light Speed' happens.

The Principle of Invariant Light Speed – "... light is always propagated in empty space with a definite velocity [speed] c which is independent of the state of motion of the emitting body." (from the preface).[1] That is, light in vacuum propagates with the speed c (a fixed constant, independent of direction) in at least one system of inertial coordinates (the "stationary system"), regardless of the state of motion of the light source.

The motion was considered mechanistic - because of legacy of Newtonian Mechanics and Galilean Transformations, e.g., absolute motion was an algebraic sum.

The motion of photon is subtle and near-first principle of Reality.  The mechanistic motion of Source is gross and far off first principle of Reality.  How could gross affect the subtle - that too when distance of layers of Realities between them was very far?  One was Matter moving through Space, and the other subtler than what made the Matter.

So what if photon is emitted from a moving electron - whose speed is varied? Or photon riding on another photon whose speed is varied?  Here my opinion is that speed of light can be altered and also broken - and are corner cases in experiments - and hard to capture.

Think "Time Travel" through Warm Holes - what it does to Speed of Light?