"An anisotropic road," Anton explained. Anka stood with her back to him. "Traffic can move only in one direction."
This is also remembered by the characters later in the book:
“Anka,” Pashka said. “Do you remember the anisotropic highway?” Anka frowned. “What highway?”
“Anisotropic. The one with the do-not-enter sign. Remember, the three of us went there?”
“I remember. It was Anton who said that it was anisotropic.”
“That was the time Anton went through the sign, and when he came back, he said that he found a blown-up bridge and the skeleton of a fascist chained to a machine gun.”
“I don’t remember that,” said Anka. “So what?”
“I often think about that highway nowadays,” said Pashka. “Like there’s some connection. The highway was anisotropic, like history. You weren’t supposed to go back. But he did go back. And stumbled on a chained skeleton.”
Hard to be a God, translated by Olena Bormashenko, Gollancz, pages 230-231.
I had to look up the meaning of "anisotropic" when I encountered it in Hard to Be a God, but was amused to learn it again in chemistry class a short while later.
I wonder what word was used for "anisotropic" in the original, and whether the original word belongs more to science than to literature, as the English word does (Wiktionary, for example, lists only a mathematics/physics definition).
What word was used in the original Russian for "anisotropic"? Does that word also usually carry a scientific definition?
I'm interested in this information mostly out of curiosity, and nothing else; however, it may have relevance to the interpretation of the symbology of that scene, asked about in the linked question.