A candle in a dark field, one ray of light leaving it

How far can an event reach?

Light Cone of Consciousness

Light from one moment only reaches so far. That limit is the cone.

A double cone on equal scale. Time is up. Space is across. The edge is 45 degrees. Gold is the future half. Blue is the past half. — Space across. Time up. Equal scale, so the edge is 45°.

The point where the cones meet is one event. It has a place, and a time.

Gold is the future. A signal from here could reach an event in that half. Blue is the past. A signal from an event in that half could have reached here. The cone is a map of possible influence, not destiny.

The surface is the speed of light. Inside it, a slower signal can still connect. Outside the cone, no signal traveling at or below the speed of light can connect the events.

Moonlight takes about 1.3 seconds to arrive. Sunlight takes about 8 minutes and 20 seconds. A star is an earlier moment.

If what you see left earlier, what is the present?

Try a point outside the cone

Henceforth, the old conception of space for itself, and time for itself shall reduce to a mere shadow, and some sort of union of the two will be found consistent with facts.

Hermann Minkowski, Cologne, 21 September 1908. Raum und Zeit. English wording from the Saha and Bose translation in The Principle of Relativity (Project Gutenberg 66944).

Portrait of Hermann Minkowski, about 1909 — Portrait about 1909. Wikimedia Commons.

Sunrise on Earth, photographed from the International Space Station

A life, named as a flame

Consciousness should be thought of as a tiny candle in a vast darkness that could easily go out. We should do anything possible to keep that flame alive.

Elon Musk, 11 February 2023. His words, on X.

Earth at dawn from Expedition 47. NASA photograph, via Wikimedia Commons.