A tiny world of three processes that do things and send each other messages. Nothing in it has a clock. Every event still knows exactly which events it came after — and which ones it has no opinion about at all. Click any dot.
Panel 1 · the engineer's diagram — three logs, left to right
causal past causal future independent — no causal link either way the event you clicked
Each dot carries its vector clock, written A·B·C: how many events on A, on B and on C this
event knows about. Arrows are messages. The stamp is the whole of what the event knows about the rest of the world.
Panel 2 · the physicist's diagram — the same events, time upward
past future elsewhere message = light ray
Nothing selected — click a dot in either panel.
Same dots, same arrows, turned ninety degrees. The dashed wedge is the fastest any message can travel in this world — slide the message dial and watch it open and close. That is the whole of what a “speed of light” does here: it decides how much of the diagram is elsewhere. The colours are what actually happened, so a dot can sit inside the wedge and still be grey: nobody sent anything that way.
Panel 3 · ask another observer
— pairs swapped order — 0 of them causally related.
Panel 4 · the twins — two routes between the same two events
This is a toy. It shows a structural analogy — the causal order that vector clocks compute in a distributed system has the same shape as the causal order of events in spacetime: past, future, and a large middle region of pairs that simply have no order between them. That is all it shows. It is not a simulation of relativity. There is no metric, no invariant speed of light, no Lorentz transformation, no gravity, and the "light cone" drawn here is just the fastest message this particular toy allows. Nothing on this page is evidence about nature. back to the demos