Not unheard of, there was a paper about doing keylogging through the tiny EM fluctuations from a computer's power supply for example: https://ieeexplore.ieee.org/document/10197022

Or data exfiltration through fan noise (60 bits/min): https://www.sciencedirect.com/science/article/abs/pii/S01674...

Or data transfer between computers using only speakers: https://arxiv.org/abs/1803.03422

The list goes on.

There's a comic out right now positing that a sufficiently intelligent AI with appropriate access could use imperceptible (to us) vibrations from mechanical computing parts like spinning rust HDD's etc.

It's a throwaway mechanic in the comic, but it seems plausible.

In certain places the power companies are/were passing time information throughout the whole grid - https://www.nist.gov/publications/time-and-frequency-electri...

That's not a comic, and it's not artificial superintelligence: https://arxiv.org/abs/1606.05915

Whatever AI comes up with by 2030 is going to be much more clever and unexpected.

The comic(manga actually) i was referring to was "Origin" by the manga author Boichi.

I'll have a read of the paper, seems like it's similar in concept

You don't need an AI to come up with remote sensing or air gap traversal capabilities though.

Note for example TEMPEST surveillance, or using a distant laser to pickup speech in a room based on window vibrations. Air-gap traversal is easily done by exploiting human weaknesses (e.g. curiousity to pick up a USB drive to see what's on it), and was successfully done by Stuxnet.

Indeed, there are lots of methods, but i was specifically thinking of the possibility of a method an isolated AI might feasibly figure out with only the tools it has easily available to it.

But as someone said earlier, the real interesting part is when/if they start figuring out novel concepts we as humans haven't even considered.