The headline that turned out to be literal
Moving clocks run slow sounds like science fiction. It's not — it's everyday physics, measured to absurd precision, used in working technology. The faster something moves, the slower its time runs relative to a stationary observer. At everyday speeds, the effect is too small to notice. At ~80% of light speed, your clock runs ~60% as fast as a stationary clock. At 99.9%, it nearly stops.
The same effect happens in gravity. Stronger gravity = slower time. A clock at sea level runs ever so slightly slower than a clock on a mountaintop. The difference is tiny — billionths of a second per day — but measurable.
GPS proves it daily
Your phone's GPS works by triangulating signals from satellites that orbit the Earth. The satellites move fast (~14,000 km/h) and sit in weaker gravity than the surface. Both effects shift their clocks relative to ours: the velocity slows them, the weaker gravity speeds them up. The two effects don't cancel; the gravity effect wins by about 38 microseconds per day.
If GPS engineers ignored this, the system would drift by about 11 km per day. Your phone would think you're somewhere you're not, and the location would get worse every minute. GPS only works because relativity is built into its software. Every time you use Google Maps, you are using a system that has Einstein's equations baked into the firmware.
What time actually is, from this view
From the relativity view, there is no universal clock. Every object carries its own clock, ticking at a rate determined by its speed and the gravity around it. The faster you go, the more your clock falls behind the clocks of slower observers. There's no way around this; it isn't an illusion or a measurement problem. Time itself is local.
This dissolves the everyday assumption that there's one true "now" everywhere in the universe. There isn't. There's your now, your friend's now, a satellite's now, an atom's now — each ticking at its own rate. They mostly agree at human speeds. They diverge as speeds and gravities increase.
Why this matters beyond physics
The frame move here is the same one from track 1 — your viewpoint is not the universe's anchor. There isn't a master clock. There are many clocks, and each is correct relative to its own motion. Once you've accepted this for time, the frame move generalizes: a lot of things you take as universally true might be local truths inside your frame, no different from your clock running at its own rate.