Phenomenon: The cosmological principle Situation where it seems false and unfalsifiable: The distant future after galaxies outside of the local group depart the cosmic event horizon
According to a widely held understanding of the far future (~100 Billion years), the distant galaxies will fade completely from view and the local group will likely merge into one galaxy. For civilizations that arise in this future orbiting trillion year old red dwarfs, the hypothesis that there are billions of galaxies just like the one they are in will be unfalsifiable. The evidence will point to all mass in the universe living in one lump with a reachable center.
Phenomenon: The cosmological principle
Situation where it seems false and unfalsifiable: The distant future after galaxies outside of the local group depart the cosmic event horizon
According to a widely held understanding of the far future (~100 Billion years), the distant galaxies will fade completely from view and the local group will likely merge into one galaxy. For civilizations that arise in this future orbiting trillion year old red dwarfs, the hypothesis that there are billions of galaxies just like the one they are in will be unfalsifiable. The evidence will point to all mass in the universe living in one lump with a reachable center.
This isn’t my example, it’s sort of the canonical scenario to use as a metaphor for how inflation-based-multiverse theories could be true yet undetectable. For example, see the afterword to “A Universe from Nothing” https://www.google.com/books/edition/A_Universe_from_Nothing/TGpbASdsIW4C?hl=en&gbpv=1&dq=A%20universe%20from%20nothing%20dawkins&pg=PA187&printsec=frontcover