Empirical Earth · Radio & Long-Distance Signals
The claim
“Radio just goes where it pleases over a flat plane — distant AM at night and submarine contact prove nothing about a globe.”
What is measured
The spectrum is organized by Earth’s shape: long waves hug or circle the globe, short waves skip over its horizon, and microwaves stop at the line of sight. explains the physics; this is the whole dial at a glance. The measured distance for each band is in radio distance records.
What would show this is wrong
tuning a cheap AM set after dark and logging stations from distant states or countries that are gone by day; or by measuring the Schumann resonance near 7.83 Hz, whose frequency is fixed by Earth’s circumference. A flat plane predicts neither the day/night swing nor a cavity that rings at the speed of light divided by 40,000 km.
Sources
This is one card from Empirical Earth, a free reference that states each flat-Earth claim at its strongest and then answers it with sourced measurements. Nothing is for sale and there are no advertisements.