In 1905 Einstein derived, from his two postulates, the conclusion
"the clock moved from A to B lags behind the other which has remained at B":
Albert Einstein, On the electrodynamics of moving bodies, 1905: "From this there ensues the following peculiar consequence. If at the points A and B of K there are stationary clocks which, viewed in the stationary system, are synchronous; and if the clock at A is moved with the velocity v along the line AB to B, then on its arrival at B the two clocks no longer synchronize, but the clock moved from A to B lags behind the other which has remained at B by tv^2/2c^2 (up to magnitudes of fourth and higher order), t being the time occupied in the journey from A to B." http://www.fourmilab.ch/etexts/einstein/specrel/www/
This conclusion does not follow from Einstein's 1905 postulates - the argument is invalid. The following two conclusions, in contrast, VALIDLY follow from the postulates:
Conclusion 1: The clock moved from A to B lags behind the other which has remained at B, as judged from the stationary system.
Conclusion 2: The clock which has remained at B lags behind the clock moved from A to B, as judged from the moving system.
Conclusions 1 and 2 (symmetrical time dilation) in their combination give no prediction for the readings of the two clocks as they meet at B.
In contrast, the invalidly deduced conclusion ("the clock moved from A to B lags behind the other which has remained at B") provides a straightforward prediction - the moving clock is slow, the stationary one is FAST (asymmetrical time dilation). The famous "travel into the future" is a direct implication - the slowness of the moving clock means that its (moving) owner can remain virtually unchanged while sixty million years are passing for the stationary system:
Thibault Damour: "The paradigm of the special relativistic upheaval of the usual concept of time is the twin paradox. Let us emphasize that this striking example of time dilation proves that time travel (towards the future) is possible. As a gedanken experiment (if we neglect practicalities such as the technology needed for reaching velocities comparable to the velocity of light, the cost of the fuel and the capacity of the traveller to sustain high accelerations), it shows that a sentient being can jump, "within a minute" (of his experienced time) arbitrarily far in the future, say sixty million years ahead, and see, and be part of, what (will) happen then on Earth. This is a clear way of realizing that the future "already exists" (as we can experience it "in a minute")." http://www.bourbaphy.fr/damourtemps.pdf
Conclusion: If logical validity is obeyed, special relativity is unable to say which clock - the moving or the stationary - lags behind the other. Einstein's invalid argument masks this inability and does say how the two clocks differ but this is not science of course.
All VALIDLY deducible consequences of Einstein's false constant-speed-of-light postulate are absurd. For instance, length contraction implies that unlimitedly long objects can gloriously be trapped, "in a compressed state", inside unlimitedly short containers:
http://math.ucr.edu/home/baez/physics/R ... _pole.html
John Baez: "These are the props. You own a barn, 40m long, with automatic doors at either end, that can be opened and closed simultaneously by a switch. You also have a pole, 80m long, which of course won't fit in the barn. [...] So, as the pole passes through the barn, there is an instant when it is completely within the barn. At that instant, you close both doors simultaneously, with your switch. [...] If it does not explode under the strain and it is sufficiently elastic it will come to rest and start to spring back to its natural shape but since it is too big for the barn the other end is now going to crash into the back door and the rod will be trapped in a compressed state inside the barn."
See, at 7:12 in the video below, how the train is trapped "in a compressed state" inside the tunnel:
"Einstein's Relativistic Train in a Tunnel Paradox: Special Relativity"
It is not difficult to realize that trapping unlimitedly long objects inside unlimitedly short containers implies unlimited compressibility and drastically violates the law of conservation of energy. The unlimitedly compressed object, in trying to restore its original volume ("spring back to its natural shape"), would produce an enormous amount of work the energy for which comes from nowhere.
At 9:01 in the above video Sarah sees the train falling through the hole, and in order to save Einstein's relativity, the authors of the video inform the gullible world that Adam as well sees the train falling through the hole. However Adam can only see this if the train undergoes an absurd bending first, as shown at 9:53 in the video and in this picture:
Clearly we have reductio ad absurdum: An absurd bending is required - it does occur in Adam's reference frame but doesn't in Sarah's. Conclusion: The underlying premise, Einstein's 1905 constant-speed-of-light postulate, is false.