Need help debunking this one, have a friend who works for a large company who just had some laptops stolen form a SUPPOSEDLY hidden place in their car.
According to the him, the thieves were able to tell that there were laptops in the car by walking past parked cars and using a device of some sort that either read an emission or picked up a signal that came from the battery.
I have never heard this, so I ask the dopers. Can you pick up a signal of some sort from laptop batteries? (Lithium Ion batteries I believe).
Almost certainly bullshit. I don’t think rechargeable batteries emit any special kind of electromagnetic radiation, especially when not in use, but even if they did, putting them inside a metal box (i.e. the closed trunk of a car) would pretty much block it all.
Actually, I wonder if your friend is talking about WiFi or Bluetooth sniffing? - if the machine is on standby, it could still be detectable, but again, the metal construction of a car is pretty effective shielding.
Not with those big windows which are much more than a wavelength long in all dimensions, it isn’t. Faraday shielding for RF is only really effective if the longest dimension of any opening is considerably less than a wavelength of the signal to be blocked.
Depends on the design of the car, I suppose - metal seat backs and a closed trunk would form more or less a closed metal box. A plastic and felt parcel shelf in a hatchback wouldn’t.
I suggested the wifi sniffing, and he wasn’t sure, which led to this post. I was under the impression the laptops were “hidden” under the seats or in the trunk, either way someplace out of direct line of sight of windows, so there would’ve been even more material blocking signals than just glass.
Line-of-sight doesn’t matter all that much in this case. Unless it’s tuned to the particular frequency, a metal object will tend to reflect an RF wave, rather than absorb it, so the signal mostly just bounces around until it finds an opening and escapes. Some of it will be absorbed, of course, and the placement of openings will tend to directionalize the signal somewhat, but enough will get out to be detectable. If you want to confirm this, just put your cellphone under your seat, in the glove compartment or even in the trunk and have someone call it.
Possibility 1:
Thieves use very sophisticated RF sniffing devices to ferret out hidden, notebooks in cars that are emitting some sort of detectable RF in powered down mode or hibernation.
Possibility 2:
Thieves are quite experienced at knowing where people hide valuables in cars
Hmm… which to choose?
Possibility 3:
Thieves hang around parking lots and watch where people hide valuables when they leave their car.
This has been reported here in Minneapolis: joggers are advised to not carry their purse or wallet with them while jogging, so they hide it somewhere in the car when they leave it in the parking lot. Thieves would be watching, see where they hid it, break the window and steal it from the car.
This reminds me of my favourite anecdote.
Train stations in Italy would have signs saying “watch out for pickpocketers”. Pickpocketers would have around near those signs because anytime someone read that sign, their hand would instinctively go for their wallets to check that it was there and the pickpocketers would know where the person kept their valuables.