In Death's End, the waves being transmitted for communication are classified as medium, long, light and short.

Picking up coordinates was the job of the main core, which swallowed all the messages passing through space: medium membrane, long membrane, light membrane, and maybe one day even short membrane.
- Bunker Era, Year 67 Orion Arm of the Milky Way, Death's End

From later exposition, we learn that the medium membrane denotes radio waves, and long membrane gravitational waves. What do the light and short membranes denote?

1 Answer 1


I don't have a hard scientific explanation for this but I interpreted these 4 mediums of communication as follows.

We're told:

Long membrane: a long, low-frequency wave form; gravitation Medium membrane: middle of the spectrum and what we call radio waves; electromagnetism

We also know from elsewhere in the series that there is neutrino-based communication (maybe neutron-based and I'm misremembering). Neutrinos interact via the weak subatomic force, and if that is the force-field through which these communications are transmitted, we now have 3/4 of the fundamental physical forces listed as a medium for communication. Because the weak force has such a short range, I presume it could be thought of as a "short medium" as communications transfer through this force field of very short-ranged forces.

This leaves the last communication medium listed, light medium, and the last fundamental physical force, the strong subatomic force. This is the force explaining the Trisolaran droplet's odd qualities. I'm not sure of the physics basis for calling communications via the strong fundamental force's field "light medium" and I'd be interested in more information. I validated this medium type on the basis that the droplet had some odd physical properties related to light and other phenomenon. Here's a description of it from Weakest Sci-Fi weapon that can destroy "The Droplet" (SpaceBattles Forums, March 2015) with emphasis added:

It's the size of a small truck, weighs ten tons, and has a perfectly smooth surface that reflects every wavelength of radiation, temperature at almost absolute zero.

The truth is it's made of Strong Interaction Material. The Trisolarans altered physical constants, making nuclear strong force have longer effective range, creating this material that is as dense as normal material, but as tough as a neutron star. It's said that it can penetrate earth like a bullet through butter. [...]

Propulsion data: It can go from 0 to 31.7 km/s in 50 seconds. Maximum speed 15% lightspeed. It's shown to take a 15 degree sharp angle turn at 31.7 km/s, without any deceleration. Whether it can perform the same turn at 15% lightspeed is unknown. It's energy source is unknown. It's controlled through quantum communication, so there is no range limit of control.

It's not a perfect match, but there is some hint that the droplet is as far removed from ordinary matter as light is as far removed from ordinary matter, potentially considered as a membrane of of spacetime. There's also the hint that "light membrane" won't be as directly 'translated' as we humans think it is, because 'light membrane' as we know it is electromagnetism, but electromagnetism is already referred to as 'medium membrane' aka radio telecommunications. Thus, I figure light membrane could be communications via the strong fundamental force's field.

For that matter, what communication membrane do the sophons work through?

  • I interpreted this as the reverse of what you did. In my reading, "light membrane" is neutrinos, which are light particles. It's implied that neutrinos are a more basic technology than the strong-matter technology, which tracks with the idea that "one day [but not yet] even short membrane" communications will be mastered by Singer's species. Commented Feb 4, 2019 at 18:12
  • @MichaelSeifert that makes sense regarding the strong force being the more advanced 'short membrane' medium. Could you clarify how neutrinos are 'light particles'? Do you mean they behave similar to photons, and/or that they are very low mass (light as in "as light as a feather" rather than light like "photons emitted by a light")?
    – cr0
    Commented Feb 5, 2019 at 15:38
  • 1
    I meant "light" as in "having very little mass". Their mass is so small that for many years after their discovery, physicists thought that they had no mass at all (similar to how photons have no mass). We now know that they have a very small mass, but it's still not clear exactly what it is. Our best estimates are that the mass of a neutrino is a few hundred thousand times smaller than the mass of the electron. Commented Feb 5, 2019 at 17:00

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