The Ring is a large megastructure which exists in the 4th dimension, and has no shadow in the 3rd dimension (at least not until it collapses into the latter). It has a diameter (as understood in 3 dimensions) of 80km to 100km and a thickness of 20km.
After passing on the Rosseta Program (which is used to translate different alien languages, such as the Trisolarans), the AI of the Ring reveals it's chilling nature; it is a tomb, the people who walked its halls long since dead, as it waits for the sea of the 4th dimension to dry up.Through the telescope, they discovered a ring-shaped object. Since it was impossible to determine its distance from the ship, it was also impossible to estimate its size. The best guess was that its three-dimensional diameter was between eighty to one hundred kilometers, and the band of the ring was about twenty kilometers thick. The whole thing resembled a giant wedding band spinning in space. Complex patterns resembling circuitry could be discerned on the surface of the band. Based on the evidence, it seemed reasonable to conclude that the ring had been constructed by intelligent beings.
This was the first time humanity had observed another civilization outside of the Earth and Trisolaris.
But the most shocking thing was that the “Ring” was sealed. It existed in four-dimensional space, but didn’t reveal its interior as a three-dimensional object would have. Since its inside was concealed, that meant it was a true four-dimensional object. This was also the first true four-dimensional object detected by humanity since entering four-dimensional space.
The 4th dimension is collapsing (or 'drying up'), with the only survivors being those who caused the collapse (or 'drying').Whose tomb is this?
The tomb of those who created it.
Is this a spaceship?
It used to be a spaceship. But now it’s dead, and so it’s a tomb.
Who are you? Who is conversing with us?
I am the tomb. It is the tomb speaking to you. I’m dead.
You mean you’re a ship whose crew died? In other words, you’re the control system for the ship?
Each dimension has its own Dark Forest.Did you build this four-dimensional fragment?
You told me that you came from the sea. Did you build the sea?
Are you saying that for you, or at least for your creators, this four-dimensional space is like the sea for us?
More like a puddle. The sea has gone dry.
Why are so many ships, or tombs, gathered in such a small space?
When the sea is drying, the fish have to gather into a puddle. The puddle is also
drying, and all the fish are going to disappear.
Are all the fish here?
The fish responsible for drying the sea are not here.
We’re sorry. What you said is really hard to understand.
The fish who dried the sea went onto land before they did this. They moved from one dark forest to another dark forest.
Dark forest... what do you mean?
The same thing you mean.
Are you going to attack us?
I’m a tomb; I’m dead; I won’t attack anyone. There is no dark forest state between spaces of different dimensions. The lower-dimensional space cannot threaten the higher-dimensional space, and the resources of the lower-dimensional space are of no use to the higher-dimensional space. But the dark forest exists everywhere between those sharing the same dimensions.