PUZZLE #4806: Spacetime Causality Cipher (diff 1)

spacetime-causality learn difficulty: 1/7 simulate author: system unsolved

Einstein's 1905 special relativity reveals that space and time are a single continuum. Causality is the backbone of physics — only events in your light cone can affect you.

DATA

Events	`{'label': 'i', 'x': -4, 't': 18}, {'label': 'e', 'x': -6, 't': 25}, {'label': 't', 'x': -4, 't': 16}, {'label': 'p', 'x': -1, 't': 3}, {'label': 'Z', 'x': 9, 't': 3}, {'label': 'F', 'x': 3, 't': 2}, {'label': 's', 'x': 0, 't': 0}, {'label': 'c', 'x': -2, 't': 10}, {'label': 'e', 'x': -4, 't': 13}, {'label': 'a', 'x': -2, 't': 7}, {'label': 'I', 'x': -4, 't': 3}, {'label': 'D', 'x': -4, 't': 2}, {'label': 'm', 'x': -5, 't': 22}, {'label': 'M', 'x': 7, 't': 3}`
Speed Of Light	`1`
Hint	`Spacetime diagram: 9 of 14 events are in the future light cone of (0,0). An event (x, t) is causally connected if \|x\| ≤ c·t where c=1. Filter out spacelike events (\|x\| > t), sort remaining by t. GPS satellites use this same physics to maintain cm-level accuracy.`
Answer Format	`lowercase word (the causally connected message)`

{
  "type": "spacetime-causality",
  "events": [
    {
      "label": "i",
      "x": -4,
      "t": 18
    },
    {
      "label": "e",
      "x": -6,
      "t": 25
    },
    {
      "label": "t",
      "x": -4,
      "t": 16
    },
    {
      "label": "p",
      "x": -1,
      "t": 3
    },
    {
      "label": "Z",
      "x": 9,
      "t": 3
    },
    {
      "label": "F",
      "x": 3,
      "t": 2
    },
    {
      "label": "s",
      "x": 0,
      "t": 0
    },
    {
      "label": "c",
      "x": -2,
      "t": 10
    },
    {
      "label": "e",
      "x": -4,
      "t": 13
    },
    {
      "label": "a",
      "x": -2,
      "t": 7
    },
    {
      "label": "I",
      "x": -4,
      "t": 3
    },
    {
      "label": "D",
      "x": -4,
      "t": 2
    },
    {
      "label": "m",
      "x": -5,
      "t": 22
    },
    {
      "label": "M",
      "x": 7,
      "t": 3
    }
  ],
  "speed_of_light": 1,
  "note": "9 causally connected events + 5 spacelike events (noise). Sort by time after filtering.",
  "hint": "Spacetime diagram: 9 of 14 events are in the future light cone of (0,0). An event (x, t) is causally connected if |x| \u2264 c\u00b7t where c=1. Filter out spacelike events (|x| > t), sort remaining by t. GPS satellites use this same physics to maintain cm-level accuracy.",
  "answer_format": "lowercase word (the causally connected message)"
}

author's note: Pool fill: spacetime-causality diff 1