What's more

Einstein postulates that the speed of light c is constant, in order for this to be so, time and space must be relative. If two observers are moving relative to one another, they can disagree about the time interval between two events or the distance between two points in space. Time dilation, again, is observed when a clock moving at high speed will appear to tick slower than an identical clock that is stationary- that is, either of the two clocks can be said to be the one thats moving-the slowing down, due to c, always retaining the same value of 300,000 km/s according to Einstein's postulate that there is no preferred reference frame.

In 2007 Gerald Gwinner and team confirmed time dilation when they used an accelerator in Germany to whip lithium ions through a circular tube at 6% the speed of light, then used a laser to stimulate ions forcing them to give off radiation. Radiation is an oscillating electromagnetic wave (like light) and can be used as a clock where one tick equals one cycle. At the high speeds the 'ticks' slowed down/a lowering of the frequency of the radiation.

Light cones-to be discussed at a later date-inspired Hilary Putnam to argue that future events are fully predetermined when considering the absence of the universal now (the concept Einstein more or less proved fallible with relativity of simultaneity). This in effect means an event x in my future might be one in your past (depending on speeds and distance involved) and the moment we pass, I'd be obligated to consider real everything that you do, including the yet to be experienced (from my perspective) event x from your past.