忒修斯之船 = Theseus’s Paradox 船舶悖論

is a thought experiment and paradox about whether an object is the same object after having all of its original components replaced over time, typically one after the other.

思考：

• 如果一艘船上的木板逐塊被替換，直到所有的木板都換成新的，那麼這艘船還是原來的那艘船嗎？
• 如果把舊木板收集起來，重新組裝成另一艘船，那麼哪一艘才是真正的「原船」？

Cell Regeneration

This can be applied to our personal identities as well. → 身體的細胞不斷地在更新，我們還是原來的自己嗎？

• The average age of all cells in the human body is 7–10 years.
• Every seven years, human beings transform into entirely new versions of themselves. This idea stems from the biological principle that our bodies replace virtually all their cells over a seven-year cycle. The person you are today doesn’t share a single cell with the version of you from seven years ago.
• 不同細胞的更新週期
  • 🧠 神經細胞 (大腦) → 幾乎不會更新，大部分人一生都帶著同一批神經元 (但有少量例外，如海馬迴的神經元可能會再生) 。
  • 💀 骨細胞 → 約 10 年完全更新一次。
  • 🩸 紅血球 → 約 120 天更新一次。
  • 🧑‍🦲 皮膚細胞 → 約 2–4 週就會更新一次。
  • 🍽️ 腸道細胞 → 內壁細胞大約 2–5 天就會更新一次。
  • 💪 肌肉細胞 → 主要是修復而非完全更換，部分可持續數年。