The Instability is a science fiction

Science fiction

Science fiction is a genre of fiction dealing with imaginary but more or less plausible content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities...

 short story

Short story

A short story is a work of fiction that is usually written in prose, often in narrative format. This format tends to be more pointed than longer works of fiction, such as novellas and novels. Short story definitions based on length differ somewhat, even among professional writers, in part because...

 by Isaac Asimov

Isaac Asimov

Isaac Asimov was an American author and professor of biochemistry at Boston University, best known for his works of science fiction and for his popular science books. Asimov was one of the most prolific writers of all time, having written or edited more than 500 books and an estimated 90,000...

 that was first published in the 1 January 1989 issue of The Observer

The Observer

The Observer is a British newspaper, published on Sundays. In the same place on the political spectrum as its daily sister paper The Guardian, which acquired it in 1993, it takes a liberal or social democratic line on most issues. It is the world's oldest Sunday newspaper.-Origins:The first issue,...

and reprinted in the collection Gold

Gold (Asimov)

Gold: The Final Science Fiction Collection is a collection of Isaac Asimov's stories and essays. The stories, which comprise its first half, are short pieces which had remained uncollected at the time of Asimov's death. As such, they have been criticized by some as inept or below par—what the...

(1995).

Plot summary

A professor tells his colleague he has made time-travel possible. He also tells him that according to his calculations, there will be another star in the Sun

Sun

The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

's place in 27 million years.
The professor makes a trip with his colleague through time to observe the dark star. After making some notes, they decide to return home. When they time travel back, the colleague notices that there is black space outside. The professor explains that time

Time

Time is a part of the measuring system used to sequence events, to compare the durations of events and the intervals between them, and to quantify rates of change such as the motions of objects....

 and space move, so their universe

Universe

The Universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature...

 has moved in an upper-dimensional level. This means they are in primeval chaos

Chaos (cosmogony)

Chaos refers to the formless or void state preceding the creation of the universe or cosmos in the Greek creation myths, more specifically the initial "gap" created by the original separation of heaven and earth....

. His colleague points out that since they are here this is not primeval chaos anymore. The professor states that his partner is right and that they have introduced an instability, but he never finishes the sentence. They are all wiped out by a Big Bang

Big Bang

The Big Bang theory is the prevailing cosmological model that explains the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the young Universe to cool and resulted in...

as a new universe is created.