OK, I quickly skimmed through the reasearch paper without going into the math, but here's the skinny of it.

They used 2 WiFi routers with 3 antennas each as cheap makeshift radar. Router antennas aren't designed to natively provide elevation and angle information so they had to get smart with the data processing. Once they have the data from the antennas they used cameras to train a proven AI model for recognizing human poses and mapping them to a 3D mesh on said data. They switched to 15 different room layout and proceeded training their model. Then, they switched to a new untrained room layout to test the models performance. The results were always below image based recognition and plummeted even lower after switching to an unknown room layout.

Unless it's buried between the math paragraphs I don't see "looking through walls" mentioned in the paper. The introduction section has a quick mention that visual obstacles provide difficulties for other human recognition technologies. Unless it's because of the implication of WiFi going through walls, I can not discern where this article got that idea from. The superimposed example images in the research paper even cut-off at the legs if the person happens to stand behind a table.

My takeaway from this is, as long as you don't make the specific placement of your multiple WiFi routers and the exact layout of your house public knowledge and don't set up multiple cameras with overlapping views to cover every angle of your home, you should be safe. Or just get single antenna routers.

How delightful.

Not sure I trust ISPs with this technology. I would say I’d rather just stop using the internet but seeing as I’m a software engineer that’s absolutely not possible :/

I' had to dig around a little but here's the link to the research paper that is detailing the technology described in this article:

Paper: https://arxiv.org/abs/2301.00250

Source: https://www.popularmechanics.com/technology/security/a42575068/scientists-use-wifi-to-see-through-walls/

I could see this deployed in hotels or other public places by the CIA so they can monitor their target's movements. The main benefit is it doesn't require placing a bug/camera in the room because the routers could be placed in another room, so if the room is swept for bugs, they won't find anything suspicious. Not too far-fetched considering the kind of shenanigans they frequently do aboard.

I'm imagining a use case of finding people buried in collapsed buildings with wifi, or is it just detecting movement... I didn't quite understand the science bit.

Is it that big of a deal when we all carry portable tracking devices with multiple cameras and microphones that can be turned on without our knowledge?
EDIT: Receipts for those who are curious what am I talking about.

This is effectively radar and makes sense as wifi is radio waves. Gonna have to start building your own home networking equipment at this rate.

Like a tera hertz scanner