In 3 Body Problem, San-Ti use Sophons to keep an eye on the humans and learn every bit of their plan.
After taking down Mike Evans’ vessel, Judgement Day, Thomas Wade and his team retrieve a storage device from him.
Humans may take a million years to access the files on this, but San-Ti let them in. The storage device contains an unknown file named sophon, which is around 100 petabytes in size.
Since the San-Ti want humans to see something, Jin and Wade agree to talk to them by using the helmet they have provided, which has a video game explaining to humans who the San-Ti are.
During their conversation with the AI inside the video game, Jin and Wade learn about the Sophons that roam the Earth.
A sentient computer
San-Ti are well aware that humans may not be as advanced as them, but their technology is fast. They never have had to restart like them, as their planet is stable.
Humans will have surpassed San-Ti by the time San-Ti reach Earth 400 years in the future. To stop that from happening, San-Ti are killing the science of humans using their Sophons.
A Sophon is a proton that the San-Ti have turned into a sentient computer. The universe has more dimensions than three. They are hidden and folded up, far too small to see.
San-Ti have the technology to unfold them. They summon energies and focus them on a single proton. When they unfold its higher dimensions, even a tiny proton becomes something very large. With that, they make a mind as large as a world.
The purpose of Sophons
San-Ti have used all of their resources to make four Sophons, two pairs of two; each pair is tangled and active on a quantum level.
Two pairs of Sophons are with San-Ti, and two are on Earth. Everything the Sophons on Earth see and hear, San-Ti see and hear too, even though they are light-years apart.
They travel at the speed of light and have the ability to show what they want humans to see, wrapping the world of humans in illusions.
Sophons entered the solar system of humans months ago. They were sent to the places where Earth’s best minds explore reality at the most fundamental level.
Using Sophons, San-Ti plan to destroy science that could defeat them. With their illusions, Sophons will make sure humans don’t progress.
Moving on, every plan the humans will come up with, San-Ti will know about it, making Sophons an incredibly powerful weapon against humans.
Once Wade and Jin leave the game, San-Ti hack into the systems on Earth. A message for humans shows up on every device on the planet, calling humans bugs.
Following that, an illusion, which seems to mirror the world, and an eye appears in the sky, suggesting that San-Ti are watching humans.
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