Proton decaydo protons die?
Super-Kamiokande has never seen a proton decay. The real particle physics behind the Cosmos Era ending “Proton decay”, from quarks to antimatter and neutrinos.
Do protons 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 game's ending “Proton decay” has the player wait at the end of the universe and watch the last proton decay. It is an ending that takes real waiting, and its unlock condition includes "wait 24 hours in real life".
This page first explains how to unlock it, then covers the real state of proton decay, then research in particle physics related to it: quarks, antimatter, why there is more matter than antimatter, and neutrinos.
How to unlock it
- Hint: Some endings can only be reached by really waiting.
- Condition: Unlock “The last proton”, witness the end of the universe, then wait 24 hours in real life.
- Reward: Unlocks the fate node “Cosmic factory” in the Energy constellation.
The ending belongs to the Physics category. The description of the “The last proton” node is to choose to stay at the end of the universe and watch the last proton decay. This ending requires a real 24-hour wait. That wait is a design choice in the game, not a requirement of any physics experiment.
The real state of things
- Never seen: Super-Kamiokande has never seen a proton decay.
- Lifetime limit: The proton lifetime is above 10³⁴ years.
- What it depends on: Whether protons decay depends on grand unified theories that have not been confirmed.
In the picture of the far future of the universe, proton decay is a "perhaps". One study 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). The evaporation of black holes comes from another discovery: quantum effects make black holes radiate energy slowly, so black holes are not eternal (Hawking, Nature, 1974).
What is inside a proton
- The quark model: Murray Gell-Mann proposed that protons and neutrons are made of smaller "quarks", bringing order to the particle zoo (Gell-Mann, Physics Letters, 1964).
- Asymptotic freedom: The closer quarks get, the weaker their interaction, and the farther apart they are, the harder they are pulled together. This explains why quarks are always confined (Gross and Wilczek, Physical Review Letters, 1973).
- The perfect liquid: Heavy-ion collisions recreated the quark–gluon plasma of the first microseconds of the universe, and it behaves like a liquid with almost no viscosity (STAR Collaboration, Nuclear Physics A, 2005).
Why there is more matter than antimatter
- The Sakharov conditions: Andrei Sakharov listed the three conditions needed for the universe to produce more matter than antimatter, which are still the starting point of research (Sakharov, JETP Letters, 1967).
- CP violation: The decay of K mesons (kaons) showed that the laws of physics for matter and antimatter are not perfectly symmetric (Christenson, Cronin, Fitch and Turlay, Physical Review Letters, 1964).
- The Dirac equation: Paul Dirac combined quantum mechanics and relativity to describe the electron, and the solutions of the equation unexpectedly predicted antimatter (Dirac, Proceedings of the Royal Society A, 1928).
- The positron: Carl Anderson photographed a positively charged electron in cosmic rays, the first time humans saw antimatter (Anderson, Physical Review, 1933).
Neutrinos
After waiting for years beside a nuclear reactor, researchers finally caught this "ghost particle" that hardly interacts with anything (Cowan, Reines et al., Science, 1956). The Super-Kamiokande detector later found that neutrinos change between three types, which means they have mass (Fukuda et al., Physical Review Letters, 1998). Super-Kamiokande is also the very detector that has "never seen a proton decay".
All of the above is related real research. It is background on particle physics, and it can neither prove nor rule out proton decay.
Game lore, not real
The words left behind by proton decay are fiction.
Want to read the originals? Search these titles
- Gell-Mann (1964): "A schematic model of baryons and mesons"
- Gross and Wilczek (1973): "Ultraviolet behavior of non-abelian gauge theories"
- Sakharov (1967): "Violation of CP invariance, C asymmetry, and baryon asymmetry of the universe"
- Christenson et al. (1964): "Evidence for the 2π decay of the K2 0 meson"
- Dirac (1928): "The quantum theory of the electron"
- Anderson (1933): "The positive electron"
- Cowan, Reines et al. (1956): "Detection of the free neutrino: a confirmation"
- Fukuda et al. (1998): "Evidence for oscillation of atmospheric neutrinos"
- STAR Collaboration (2005): "Experimental and theoretical challenges in the search for the quark–gluon plasma"
- Hawking (1974): "Black hole explosions?"
- Adams and Laughlin (1997): "A dying universe: the long-term fate and evolution of astrophysical objects"
Real basis
Super-Kamiokande has never seen a proton decay, so the proton lifetime exceeds 10³⁴ years; whether it decays at all depends on grand unified theories that remain unconfirmed.
The last proton: Choose to keep watch at the end of the universe and see the last proton decay.
Related research
These studies relate to this topic but are not direct proof of this page.
The quark model: Gell-Mann proposed that protons and neutrons are made of smaller “quarks,” bringing order to the particle zoo.
Source: Gell-Mann, Physics Letters 1964, "A schematic model of baryons and mesons"
Asymptotic freedom: The closer quarks get, the weaker their interaction; the farther apart, the tighter they pull. This explains why quarks are always locked together.
Source: Gross & Wilczek, Physical Review Letters 1973, "Ultraviolet behavior of non-abelian gauge theories"
Sakharov conditions: Sakharov listed three conditions needed for the universe to produce “more matter than antimatter.” They are still the starting point of research.
Source: Sakharov, JETP Letters 1967, "Violation of CP invariance, C asymmetry, and baryon asymmetry of the universe"
CP violation: The decay of the K meson showed that the laws of physics for matter and antimatter are not perfectly symmetric.
Source: Christenson, Cronin, Fitch & Turlay, Physical Review Letters 1964, "Evidence for the 2π decay of the K2 0 meson"
The positron: Anderson photographed a positively charged electron in cosmic rays, the first time humans saw antimatter.
Source: Anderson, Physical Review 1933, "The positive electron"
The Dirac equation: Dirac combined quantum mechanics and relativity to describe the electron, and a solution of his equation unexpectedly predicted antimatter.
Source: Dirac, Proceedings of the Royal Society A 1928, "The quantum theory of the electron"
Catching the neutrino: After waiting by a nuclear reactor for years, they finally caught this “ghost particle” that barely interacts with anything.
Source: Cowan, Reines et al., Science 1956, "Detection of the free neutrino: a confirmation"
Neutrino oscillation: The Super-Kamiokande detector found that neutrinos change between three types, which means they have mass.
Source: Fukuda et al. (Super-Kamiokande), Physical Review Letters 1998, "Evidence for oscillation of atmospheric neutrinos"
The perfect liquid: Heavy-ion collisions recreated the quark–gluon plasma of the first few microseconds of the universe, which behaves like a liquid with almost no viscosity.
Source: STAR Collaboration, Nuclear Physics A 2005, "Experimental and theoretical challenges in the search for the quark–gluon plasma"
Black holes evaporate: Quantum effects make black holes radiate energy slowly. Black holes are not eternal and will eventually evaporate.
Source: Hawking, Nature 1974, "Black hole explosions?"
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)
- Words left behind by proton decay are fiction.
- Node “The last proton”: This ending requires a real wait of 24 hours.