stollike weapon and checked it.

In theory, the Ghaldron-Hesthor paratemporal transposition field was
uninfluenced by material objects outside it. In practice, however,
such objects occasionally intruded, and sometimes they were alive and
hostile. The last time he had been in this conveyer room, he had seen
a quartet of returning officers emerge from a conveyer dome dragging
a dead lion by the tail. The sigma-ray needler, which he carried, was
the only weapon which could be used, under the circumstances. It had
no effect whatever on any material structure and could be used inside
an activated conveyer without deranging the conductor-mesh, as, say, a
bullet or the vibration of an ultrasonic paralyzer would do, and it
was instantly fatal to anything having a central nervous system. It
was a good weapon to use outtime for that reason, also; even on the
most civilized time-line, the most elaborate autopsy would reveal no
specific cause of death.

"What's the Esaron Sector like?" Dalla asked, as the conveyer dome
around them coruscated with shifting light and vanished.

"Third Level; probability of abortive attempt to colonize this planet
from Mars about a hundred thousand years ago," he said. "A few
survivors--a shipload or so--were left to shift for themselves while
the parent civilization on Mars died out. They lost all vestiges of
their original Martian culture, even memory of their extraterrestrial
origin. About fifteen hundred to two thousand years ago, a reasonably
high electrochemical civilization developed and they began working
with nuclear energy and developed reaction-drive spaceships. But
they'd concentrated so on the inorganic sciences, and so far neglected
the bio-sciences, that when they launched their first ship for Venus
they hadn't yet developed a germ theory of disease."

"What happened when they ran into the green-vomit fever?" Dalla asked.

"About what you could expect. The first--and only--ship to return
brought it back to Terra. Of course, nobody knew what it was, and
before the epidemic ended, it had almost depopulated this planet.
Since the survivors knew nothing about germs, they blamed it on the
anger of the gods--the old story of recourse to supernaturalism in the
absence of a known explanation--and a fanatically anti-scientific cult
got control. Of course, space travel was taboo; so was nuclear and
even electric power. For some reason, steam power and gunpowder
weren't offensive to the gods