Wrong-Way Street

by Larry Niven

Ever since an accident that killed his eight-year-old brother, Mike Capoferri has been interested in time travel, and now he thinks one of the alien artifacts found on the moon is a time machine.

Mike was a recent but ardent science-fiction fan. “I want to change it, Dr. Stuart,” he said earnestly. “I want to go back to four weeks ago and take away Tony’s Flexy.” He meant it, of course.

“Wrong-Way Street” by Larry Niven, in Galaxy, April 1965.

At the Core

by Larry Niven

“At the Core” by Larry Niven, If, September 1966.

Neutron Star

by Larry Niven

“Neutron Star” by Larry Niven, If, September/October 1966.

For a Foggy Night

by Larry Niven

“For a Foggy Night” by Larry Niven, in Decal, July 1968.

All the Myriad Ways

Detective-Lieutenant Gene Trimble suspects that the recent spate of suicides and violent crime is somehow connected to the discovery that the many worlds interpretation of quantum physics is real and each of those worlds can be traveled to.

— Michael Main

There were timelines branching and branching, a mega-universe of universes, millions more every minute. Billions? Trillions? Trimble didn’t understand the theory, though God knows he’d tried. The universe split every time someone made a decision. Split, so that every decision every made could go both ways. Every choice ever made by every man, woman and child on Earth was reversed in the universe next door.

“All the Myriad Ways” by Larry Niven, in Galaxy, October 1968.

The Flight of the Horse

by Larry Niven

“The Flight of the Horse” by Larry Niven, Magazine of Fantasy and Science Fiction, October 1969.

Leviathan!

by Larry Niven

“Leviathan!” by Larry Niven, Playboy,August 1970.

Bird in the Hand

by Larry Niven

“Bird in the Hand” by Larry Niven, Magazine of Fantasy and Science Fiction, October 1970.

There’s a Wolf in My Time Machine

by Larry Niven

“There’s a Wolf in My Time Machine” by Larry Niven, Magazine of Fantasy and Science Fiction, June 1971.

There’s a Wolf in My Time Machine

by Larry Niven

“There’s a Wolf in My Time Machine” by Larry Niven, Magazine of Fantasy and Science Fiction, June 1971.

The State 0.1

Rammer

by Larry Niven

“Rammer” by Larry Niven, Galaxy Magazine, December 1971.

Death in a Cage

by Larry Niven

“Death in a Cage” by Larry Niven, in Flight of the Horse (Ballantine Books, September 1973).

Singularities Make Me Nervous

by Larry Niven

“Singularities Make Me Nervous” by Larry Niven, in Stellar 1, edited by Judy-Lynn del Rey (Ballantine Books, September 1974).

Gil Hamilton

ARM

by Larry Niven

[ex=bare]“ARM ” | The last day of creation[/ex] by Larry Niven, in Epoch, edited by Roger Elwood and Robert Silverberg (Berkley, November 1975).

The State 0.2

Down and Out

by Larry Niven

“Down and Out” by Larry Niven, Galaxy Magazine, February 1976.

The State 0.3

Children of the State

by Larry Niven

Children of the State by Larry Niven, 3 pts., Galaxy Magazine, September 1976 to November 1976.

The State 1

A World Out of Time

by Larry Niven

A World Out of Time by Larry Niven (Holt, Reinhart and Winston, September 1976).

Rotating Cylinders and the Possibility of Global Causality Violation

by Larry Niven

A mathematician named Quifting has a way to use a time machine to end the war with the Hallane Regency once and for all.

Did nobody ever finish one of these, ah, time machines?

“Rotating Cylinders and the Possibility of Global Causality Violation” by Larry Niven, in Analog, August 1977.

The State 2

The Integral Trees

by Larry Niven

The Integral Trees by Larry Niven, 4 pts., Analog Science Fiction / Science Fact, October 1983 to [Error: Missing '[/ex]' tag for wikilink]

The State 3

The Smoke Ring

by Larry Niven

The Smoke Ring by Larry Niven, 4 pts., Analog Science Fiction / Science Fact, January 1987 to [Error: Missing '[/ex]' tag for wikilink]

The Return of William Proxmire

by Larry Niven

“The Return of William Proxmire” by Larry Niven, in What Might Have Been, vol. 1, Alternate Empires, edited by Gregory Benford and Martin H. Greenberg (Bantam Books, August 1989).

The State 3.1

The Kiteman

by Larry Niven

“The Kiteman” by Larry Niven, in N-Space (Tor, September 1990).

Svetz

Rainbow Mars

by Larry Niven

Rainbow Mars by Larry Niven, in Rainbow Mars (TorNovember 2013, March 1999).

The Man in the Pink Shirt

by Larry Niven

Hanny Sindros, a writer, travels back to meet John W. Campbell, Jr., and talk about whether the Nazis might gain something from Cleve Cartmill’s atomic power stories.

What if these German spies see that Astounding has suddenly stopped publishing anything about atomic bombs? What would they do? They’d think we were hiding something.

“The Man in the Pink Shirt” by Larry Niven, in Analog, November 2012.

Time Patrol homage

The Far End

by Larry Niven

“The Far End” by Larry Niven, in Multiverse: Exploring Poul Anderson's Worlds, edited by Greg Bear and Gardner Dozois (Subterranean, May 2014).