WiFi signals can measure heart rate

Can't help but think of the Star Trek TOS episode where Kirk is accused of murder and they find the "murder victim" in the ship by identifying and isolating heart beats until they discover he must still be aboard. It's been almost 60 years since the episode came out, but still sorry if that's a spoiler

Classic Star Trek (speaking as a fan). They can scan an entire planet to find a lost crew member, but can’t tell how many people are on their own ship. And they have universal audio surveillance on the ship but still have to use wall intercoms.

There's a single DS9 episode[0] where they reveal that the Captain can actually spy on everyone on the ship at once. Like tap into a video feed and listen to conversations. But then we never see this happen again.

My headcannon for this is that even though it's technically possible, it's so unethical they just choose to never do it.

[0] https://memory-alpha.fandom.com/wiki/Valiant_(episode)#:~:te...