Scene Context: Inside the lava tube, Les trails a fiber-optic cable behind him because radio communication with the Piroe cannot penetrate the basalt.
Essence of the Phenomenon: Solid rock effectively shields or severely attenuates radio signals, particularly given the uneven geometry of a cave and dozens of meters of stone overhead. Under such conditions, a hardwired connection becomes infinitely more reliable than a wireless one.
Scientific Basis: Fiber optics do not "punch through" rock with radio waves; they physically transmit the signal inside the cable via light pulses. For subterranean cavities, basalt tubes, and deep caves, this is a much cleaner engineering solution than attempting to maintain a stable radio link through solid stone.
Current Limitations: Such a connection is only as reliable as the physical line itself. In the scene, the fiber-optic cable is severed not by exotic physics, but by the mundane mechanics of an impact and cave-in. This is the true vulnerability of a hardwired channel: it is signal-stable but physically fragile.