Chapter 3

We can’t see the others

Even if bubble universes are real, light from outside our region can’t reach us. The limit isn’t bad telescopes — it’s causality.

Cosmic horizon

Only a finite sphere of spacetime is in our past light cone. Beyond that particle horizon, events never get a vote in what we observe. Other inflating regions / bubbles can sit forever outside that sphere.

“No photo of Universe B” is expected — not a refutation.

Your observable bubble

Drag to move “you.” The glowing circle is a toy horizon. Stars outside never arrive.

inside horizon: — drag the center

Living in a corner

The chat line lands here: “we’re very likely living in one small corner of a much larger multiverse.” Larger not as a place you could fly to next Tuesday — larger as a structure of regions forever out of causal contact.

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