Youthe final ending and the real science of all 15 others

A summary of the real science behind the other 15 Cosmos Era endings. See the real basis for each ending and learn what is true and what is game lore.

The last ending is called “You”, and its unlock condition is one sentence: witness the other 15 endings. Its content is your entire play record on this device, and everything else is game lore. So this page has no new science to explain. It puts the real basis behind the first 15 endings in one place, so that by the end you know which parts are true and which are fiction.

How to unlock it

  • Hint: Witness all the other endings.
  • Condition: Witness the other 15 endings.
  • Reward: Opens free mode: you can specify the anomalous history of the next universe. The signature at the end of chapter 1 of the Observer's log changes to “You”.

The ending belongs to the Ultimate category.

The real basis of the 15 endings

Each ending has one sentence of "real basis". Here they are in order:

  • Time loop: Closed timelike curves are solutions allowed by the equations of general relativity (Morris, Thorne and Yurtsever, 1988). In 1991 Deutsch showed that the quantum version can avoid the grandfather paradox.
  • What dark matter is: Dark matter makes up more than 80% of the matter in the universe, and galaxies really do form inside dark matter halos. It is detected only through gravity, and what it is remains unknown.
  • Words in the sky: Real constellations are just stars that humans connected because they lie in similar directions, even though they may be very far apart.
  • Rewind: DESI's 2025 data favor "dark energy weakening over time" at 2.8 to 4.2 standard deviations, but that is short of the 5 standard deviations needed for confirmation.
  • All the planets: Collective decision-making in bee and ant colonies is real, and brain-to-brain interfaces have already let three people cooperate on a simple task.
  • The other end of the wormhole: Traversable wormholes are solutions allowed by general relativity, but they need negative energy, and both mouths must first be moved into place at sublight speed.
  • Vacuum decay: By current measurements, our vacuum could be metastable, with an expected lifetime of about 10¹³⁹ years. The theory of vacuum decay was worked out by Coleman and De Luccia in 1980.
  • Silence: No signal from an extraterrestrial civilization has ever been confirmed, which is the Fermi paradox. Brin's 1983 "Great Silence" systematically discussed the possible reasons for the quiet.
  • Baby universe: Farhi and Guth in 1987, and Farhi, Guth and Guven in 1990, seriously studied the physical conditions for making a universe in a lab.
  • Recursion: Bostrom's 2003 simulation argument is a serious philosophical argument. In 2012 physicists proposed a way to test whether the universe is being computed on a lattice.
  • They can see you: A 2019 photon experiment tested "Wigner's friend", and the result hints that different observers' records can contradict each other.
  • They moved into your device: Landauer's principle sets a physical floor on the energy cost of computing.
  • Proton decay: Super-Kamiokande has never seen a proton decay, which puts the proton lifetime above 10³⁴ years. Whether protons decay at all depends on grand unified theories that have not been confirmed.
  • The trilobites' civilization: Trilobites survived for nearly 300 million years and vanished in the end-Permian mass extinction. Their compound eyes really were made of calcite crystals.
  • The microbes won: For roughly the first 3 billion years of life on Earth, there were almost only microbes, and bacterial biofilms really do coordinate their colonies with waves of potassium ions.

How to read this list

These 15 sentences have one thing in common: each one is about real science, while each ending itself is a fictional idea that pushes that real science to the extreme. To see a fuller explanation of any one ending, go to its own ending page.

All the endings happen after “End of the universe”, so this page lists just one related study: it worked out the fate of the universe trillions of years from now and beyond: stars burn out, protons may decay, and black holes eventually evaporate (Adams and Laughlin, Reviews of Modern Physics, 1997). Its original title is "A dying universe: the long-term fate and evolution of astrophysical objects".

Game lore, not real

The ending “You” shows your entire play record on this device, and everything else is game lore.

Real basis

  • All your play records on this device.

  • Ending “Time loop”: closed timelike curves are solutions allowed by the equations of general relativity (Morris, Thorne and Yurtsever 1988); in 1991 Deutsch showed that a quantum version can avoid the grandfather paradox.

  • Ending “What dark matter is”: dark matter makes up a bit over 80% of the matter in the universe, and galaxies really do form inside dark matter halos; it is detected only through gravity, and what it is remains unknown.

  • Ending “Words in the sky”: real constellations are just stars that humans connected because they lie in similar directions, though they may be at very different distances.

  • Ending “Rewind”: DESI’s 2025 data favor “dark energy weakening over time” at 2.8 to 4.2 standard deviations, but have not reached the 5 standard deviations needed for confirmation.

  • Ending “All the planets”: collective decision-making really exists in bee swarms and ant colonies; brain-to-brain interfaces already let three people cooperate on simple tasks.

  • Ending “The other end of the wormhole”: traversable wormholes are solutions allowed by general relativity, but they require negative energy; the two mouths must first be moved into place at sub-light speed.

  • Ending “Vacuum decay”: by current measurements, our vacuum may be metastable, but with an expected lifetime of about 10¹³⁹ years; the theory of vacuum decay was given by Coleman and De Luccia in 1980.

  • Ending “Silence”: no signal from any extraterrestrial civilization has ever been confirmed, which is the Fermi paradox; Brin’s 1983 “Great Silence” systematically discussed the possible reasons for the silence.

  • Ending “Baby universe”: Farhi and Guth (1987) and Farhi, Guth and Guven (1990) seriously studied the physical conditions for making a universe in a lab.

  • Ending “Recursion”: Bostrom’s 2003 simulation argument is a serious philosophical argument; in 2012 physicists proposed ways to test whether the universe is being computed on a lattice.

  • Ending “They can see you”: a 2019 photon experiment tested “Wigner’s friend”, and the result suggests that records of different observers can contradict each other.

  • Ending “They moved into your device”: Landauer’s principle gives the physical lower limit on the energy cost of computation.

  • Ending “Proton decay”: Super-Kamiokande has never seen a proton decay, and the proton lifetime exceeds 10³⁴ years; whether it decays depends on grand unified theories that remain unconfirmed.

  • Ending “The trilobites’ civilization”: trilobites survived for nearly 300 million years and vanished in the end-Permian mass extinction; their compound eyes really were made of calcite crystals.

  • Ending “The microbes won”: for roughly the first 3 billion years of life on Earth there were almost only microbes; bacterial biofilms really do use waves of potassium ions to coordinate the colony.

Related research

These studies relate to this topic but are not direct proof of this page.

  • The last chapter of the universe: Worked out the fate of the universe over trillions of years and beyond: stars go out, protons perhaps decay, and black holes finally evaporate.

    Source: Adams & Laughlin, Reviews of Modern Physics 1997, "A dying universe: the long-term fate and evolution of astrophysical objects"

Game lore (fictional)

  • Everything else.
See it in the game