While driving with the phone magnetometer running I saw this while going over three overpasses, that is, three times there were steel girders under my car.
Fig 1, absolute magnetic field measured while driving. The three spikes happened while driving over three overpasses.
shout-out to the PhyPhox app.
I think this means electric current flows through steel girders when they span a distance of dirt. Why else would there be a measurable field? Of course as a control I should find some large I-Beams sitting in air, and run over them with my magnetometer.
I heard on an interview that Big Tech is collecting our altitude. Why? The simple answer is, because they can. Below is the plot of pressure as I walk upstairs. I had no idea that walking upstairs was so easily measurable through the pressure sensor in my phone.
Figure 2, the air pressure while walking upstairs
Our altitude is being fed into giant databases, and the AI is figuring out how to use this to influence our buying habits, and the new things we are being influenced towards & away from.