What's the first appearance of monomolecular wire or nanofilament (extremely thin, superstrong, hence cuts almost anything)?

Question

There's a pivotal scene in Larry Niven's short story, "The Borderland of Sol" in which Beowulf Shaeffer uses a length of Sinclair monofilament -- a monomolecular wire as strong as molecular bonds and only a few atoms thick -- to defeat the villain. His novel, Ringworld, had "shadow square wire" that kept the panels in place to give night and day on the titular construct -- so fine that when a few thousand miles of it tangled on the ground, it looked like fog (but cut like steel wool made of razor blades).

I've seen similar concepts in other stories -- one of the terrorism scenes in John Brunner's Stand on Zanzibar has a similar wire strung across a road and cutting through a vehicle and its passengers, and based on another question similar material appears in The Three Body Problem.

My question is, what's the earliest appearance in SF of this kind of super-strong, super-fine wire or thread?

Answer 1

As noted, The Man in the White Suit and "The Incubi of Parallel X" both effectively have monomolecular wire, but the first example of it being used to cut may be the "borazon-tungsten filament" in G. Randall Garrett's "Thin Edge." (Analog, Dec 1963) as per the Wikipedia entry.

The cable they didn't have to worry about. Each strand was a fine wire of two-phase material—the harder phase being borazon, the softer being tungsten carbide. Winding these fine wires into a cable made a flexible rope that was essentially a three-phase material—with the vacuum of space acting as the third phase. With a tensile strength above a hundred million pounds per square inch, a half inch cable could easily apply more pressure to that anchor than it could take. There was a need for that strong cable: a snapping cable that is suddenly released from a tension of many millions of pounds can be dangerous in the extreme, forming a writhing whip that can lash through a spacesuit as though it did not exist. What damage it did to flesh and bone after that was of minor importance; a man who loses all his air in explosive decompression certainly has very little use for flesh and bone thereafter.

....

"The composition is simple. Basically, it is a two-phase material-like fiberglass. It consists of a strong, hard material imbedded in a matrix of softer material. The difference is that, in this case, the stronger fibers are borazon—boron nitride formed under tremendous pressure—while the softer matrix is composed of tungsten carbide. If the fibers are only a thousandth or two thousandths of an inch in diameter—the thickness of a human hair or less—then the cable from which they are made has tremendous strength and flexibility."

....

"Why do I give it to you? Because it will kill you. You have seen what the stuff will do. A strand a thousandth of an inch thick, encased in silon for lubrication purposes, got me out of that filthy hole you call a prison. You've heard about that?"

Fergus blinked. "You cut yourself out of there with the cable you're talking about?"

"Not with the cable. With a thin fiber. With one of the hairlike fibers that makes up the cable. Did you ever cut cheese with a wire? In effect, that wire is a knife—a knife that consists only of an edge.

Answer 2

The earliest appearance of a superstrong filament that can cut through things seems to be Theodore Sturgeon's "molecularly condensed fibre" in "The Incubi of Parallel X," Planet Stories September 1951:

Garth took pity on him — he was obviously about to burst with curiosity. He held up the thread. "Break off a piece for me, Bronze boy."

Bronze took the end of the thread, wrapped it around his fists, and — "Wait!" laughed Garth.

He picked up two heavy pieces of tree branch, unwound the thread from the big unresisting fists, and took a couple of turns of the thread around each piece of wood, leaving about six inches of thread between them. "Now try it," he said. "Grip the wood, not the thread."

Puzzled, Bronze grasped the two pieces of wood and pulled. The thread went taut with a musical twang which rose in pitch as Bronze pulled. A look of utter amazement crossed his broad face. He relaxed, turned the two pieces of wood so that he wound up more thread and had only two inches between them. He set his back against a tree, knotted his jaw, and, with his great hands close to his chest, began to pull. His triceps swelled until the stretched skin shone. His body moved visibly away from the tree that he leaned against as his scapular muscles bunched and crawled.

There was a muffled crackling from his shoulders, and Garth stepped forward in alarm. Then one of the pieces of wood gave. The thread sliced through it like a scythe through a stand of wheat, and Bronze stood gasping, staring foolishly at the cleancut stub of branch in his hand. The thread fell away, unstretched, unbroken.

"I gave you the wood," Garth grinned, "because it would've sliced through your paws."

"What Ffanx stuff is that?" gasped Bronze.

"That isn't Ffanx stuff; it's strictly human, molecularly condensed fibre spun under massive ion bombardment, if that makes any never mind to you. It has linear cohesion in the order of six tons test and eight and a half tons breaking strain. And it has no rotary cohesion at all."

You can read the story at the Internet Archive.