WiFi signals can measure heart rate

WiFi equipment can see your heart beating, but don't worry, it cannot possibly have any harmful effects on human physiology.

What? A camera can see you but cannot impact your physiology unless thrown at you.

To add to the comment on cameras: https://www.youtube.com/watch?v=e9ASH8IBJ2U

Or swallowed :p

A sonogram can see your heart beating too, but no one thinks sonograms are dangerous(because they are not).

Unsolicited remote sonograms are stopped by walls, floors, ceilings and doors, unlike wireless radio networks.

I prefer my wavefunction non-collapsed.

Except for the few you’re meant to

For now

A camera detects light. Light can certainly be dangerous to you.

Sound can certainly be dangerous to you.

I have a superficial radial artery. You can take my pulse just by looking at the shadow on my wrist moving in the right lighting. Does this have "harmful effects" on my physiology?

So can water. That doesn't make it inherently dangerous in all amounts.

As far as we know, it really doesn't, at least not at the energy levels used in practice. Blasting 2.4GHz at the same energy levels as a microwave oven would cook your flesh if you were sufficiently close to the emitter. But that doesn't happen.

Ultrasound can be used to blast tumours or break kidney stones. And according to Wikipedia there seems to be a really weird correlation between having an ultrasound and being lefthanded. But that sounds almost too ridiculous to be true.

A concrete wall stops wifi pretty well.

How thick a concrete wall is needed to stop wifi? Or does the concrete wall contain fine wire mesh?

The most selfies I've ever taken in a weekend.

Please don't post sneering comments like this on HN. The point itself may be valid, and raises a question worth discussing, but when it's phrased like this it crosses into shallow dismissal and flamebait territory, and is against the HN guidelines. We've had to ask you to observe the guidelines in just the past few months. You're a longtime community member and we value the positive contributions you've made over the years, but we need everyone to make the effort to use HN in the intended spirit.

https://news.ycombinator.com/newsguidelines.html

you can get RF burns from VHF/UHF/microwave frequencies with milliwatts if you somehow short the transmission line across yourself, even though the actual voltage and amperage going across your skin is practically infinitesimal. the amount of contact - if any - needed decreases with the RF power. wifi is "legal" up to 1W EIRP, which means a unity gain antenna capable device can output 1000mW at the terminal.

the FCC "considers 50 watts to be the lowest power above which radiation must be considered [...]" for radio transmitters. in 1996.

further:

> Conversely, lower frequencies penetrate deeper; at 5.8 GHz (3.2 mm) the depth most of the energy is dissipated in the first millimeter of the skin; the 2.45 GHz frequency microwaves commonly used in microwave ovens can deliver energy deeper into the tissue; the generally accepted value is 17 mm for muscle tissue.

> The damage can be spread over a large area, when the source is a relatively distant energy radiator, or a very small (though possibly deep) area, when the body comes to a direct contact with the source (e.g. a wire or a connector pin).

note the microwave 2.45GHz part says frequency, not wattage, power, whatever. a home router's antenna's radome (or rubber duck or whatever) touching your arm will penetrate it quite far.

anyhow i've gotten RF burns before, just to see if it was BS or not, at real low wattage (around 1W at the terminal) and it leaves a discolored mark on your skin in a straight line between the contact points and feels like you got a small burn there. The frequency i "burned" myself with was ~145MHz.

This is all to say "it doesn't matter if it's ionizing, it still heats things up."

ETA:

> Frequencies considered especially dangerous occur where the human body can become resonant, at 35 MHz, 70 MHz, 80-100 MHz, 400 MHz, and 1 GHz

If by "fine" you mean minimum ~10mm rebar then yes

Have you never walked into a building an lost cell reception?

OK, I can do that.

Much appreciated!

Found a table with attenuation by frequency and building material, e.g. low-emission glass can block more than concrete, https://www.signalbooster.com/blogs/news/how-much-which-buil...

                        800Mhz     1900Mhz
  1/2" Drywall          2.03 dB    2.43 dB
  Venetian Plaster      7.91 dB    16.22 dB
  6" Concrete Wall      10.11 dB   19.41 dB
  Glass Window          4.35 dB    4.38 dB
  Low Emission Glass    33.8 dB    33.8 dB
  Brick                 7.57 dB    14.66 dB
  Solid Wooden Door     6.11 dB    12.33 dB

How is that relevant? The camera isn’t blasting you with harmful light.