Einstein's SR a description of observations or a description of realit

is newtonian relativity a description of observations or a description of reality (or both)?

(and is the distinction important?)

 

What's the difference?

 

Perhaps you are alluding to Newton's theory, which contains a description (postulate) of hidden reality and a related description of observations (laws of motion). But only the description of observations can be tested, and most textbooks only mention the laws of motion. Is that what you are thinking of perhaps?

If so, then Einstein's SR is a description of observations. That is implicit in the definitions here which are -on purpose- completely free of metaphysics, starting form §1: http://www.fourmilab.ch/etexts/einstein/specrel/www/

Also the "speed of light in empty space" is purely operationally defined. The one-way speed even depends on one's free choice of clock synchronization. He phrased that more explicitly two years later as follows:

We now assume that the clocks can be adjusted in such a way that the propagation velocity of every light ray in vacuum - measured by means of these clocks - becomes everywhere equal to a universal constant c, provided that the coordinate system is not accelerated.

[addendum] As SR doesn't contain metaphysics, different people fill it in with different philosophical interpretations about "reality". And this forum is not the place for long elaborations about opinions that cannot be tested by experiment. Nevertheless, the distinction that you seem to make can be important for a precise understanding of what the theory entails. Indeed, the theory limits itself to predictions of observations.

 

Your "fact" is not true. You're confusing objects with terms of description. According to special relativity all the spatio-temporal relations between events are absolute objective facts, and do not differ from one observer to another. However, different observers may certainly use different terms to describe things.

Think about describing things on a flat plane surface in terms of a Cartesian coordinate system x,y, and then think about describing those same things in terms of a different Cartesian coordinate system X,Y. The descriptions will differ to the extent that the range of x values occupied by a certain object may be different than the range of X values occupied by that object. But this doesn't imply that the "realities" of the objects are different for observers who use those two different coordinate systems. Yes, the terms of description are different (and of course the relations between the objects and each observer may be different), but the things being described are not different. This isn't unique to special relativity. The same applies to everyday life, so it shouldn't be hard to understand.

People get confused when they first hear about special relativity because they have never previously thought about where our "natural" terms of spatio-temporal description (usually inertial coordinate systems) come from, how they are defined, and what they actually represent, especially when it comes to the time coordinates of events.

 

no, he never sees it stop

he only sees it slow down … so what?

(and this has nothing to do with SR anyway)​

 

Light pulses sent by the infalling observer to an external static observer take an infinite time to actually travel to said static observer, in the limit as the infalling observer reaches the event horizon. So there is no contradiction, it's just that the external observer's communication ties with the infalling observer are cutoff in the limit as ##r\rightarrow 2M##.