Since the 1950s, this type of fiction has to a large extent merged with science fictional tropes involving cross-time travel between alternate histories or psychic awareness of the existence of " our " universe by the people in another ; or ordinary voyaging uptime ( into the past ) or downtime ( into the future ) that results in history splitting into two or more time-lines.

The history of the universe is divided into different periods called epochs, according to the dominant forces and processes in each period.

Michael Rowan-Robinson emphasizes the importance of the Copernican principle: " It is evident that in the post-Copernican era of human history, no well-informed and rational person can imagine that the Earth occupies a unique position in the universe.

In a similar way, evidence about the history of the universe is drawn from astronomy, astrophysics, planetary geology, and physics.

Since there is no conclusive or certifiable evidence on Earth or elsewhere in the known universe of other intelligent life after 13. 7 billion years of the universe's history, we have the conflict requiring a resolution.

Even if such civilizations are rare, the scale argument indicates they should exist somewhere at some point during the history of the universe, and since they could be detected from far away over a considerable period of time, many more potential sites for their origin are within range of our observation.

In temporal logic, possible worlds are in a " state of the universe at some point in history " and are sometimes called " time-slices ".

Starburst galaxies were more common during the early history of the universe, and, at present, still contribute an estimated 15 % to the total star production rate.

The study of galactic formation and evolution attempts to answer questions regarding how galaxies formed and their evolutionary path over the history of the universe.

Infrared is also used to observe distant, red-shifted galaxies that were formed much earlier in the history of the universe.

This observation made him one of the first scholars in ancient physics to address the role of time in the universe, one of the most important concepts even in the modern history of physics.

An always extant being called Qfwfq narrates all of the stories save two, each of which is a memory of an event in the history of the universe.

In the late 1980s, Niven opened up this gap in the known space timeline as a shared universe, and the stories of the Man-Kzin Wars volumes fill in that history, bridging the two settings.

The final result will be a musical “ history of the universe ", from the Big Bang onwards through galaxy and star formation, up until modern times, including images from the Hubble Space Telescope and rhythms derived from the cosmic background radiation, supernovae, quasars, and many other astrophysical phenomena.

One cannot normally alter the Marvel Universe's history ; if a time-traveller should cause an alteration to the established flow of events at some point in the past, a divergent universe will simply " branch out " from the existing timeline, and the time-traveller will still return to his or her unaltered original universe.

The story of the Night's Dawn Trilogy is separated over three books: The Reality Dysfunction ( 1996 ), The Neutronium Alchemist ( 1997 ), and The Naked God ( 1999 ); but is also supported by " A Second Chance at Eden ", a collection of short stories which provide insight into the history of Hamilton's universe.

When Steven Moffat took over in 2010, he introduced cracks in the universe which erase events and individuals from history ; using this device, he ' undid ' the events of " Journey's End " and " The Next Doctor " so that in the series ' narrative, the people of Earth would be ( once again ) unaware of alien life.

Thus, by firing the weapon, Annorax makes a retcon to the history of the universe.

These stories may use time travel to change the past, or may simply set a story in a universe with a different history from our own.

* Archaeoastronomy-the history of human understanding of the universe

The universe has not been the same at all times in its history ; for example, the relative populations of quasars and galaxies have changed and space itself appears to have expanded.

The relative fractions of different chemical elements — particularly the lightest atoms such as hydrogen, deuterium and helium — seem to be identical throughout the universe and throughout its observable history.

In cosmology, solving for the history of the universe is done by calculating R as a function of time, given k and the value of the cosmological constant Λ, which is a ( small ) parameter in Einstein's field equations.

This is the only case in modern history of a people of Britannic origin submitting without continued struggle to what they view as foreign domination.

The general acceptance of the idea of governmental ( i.e., societal ) responsibility for the economic well-being of the American people is surely one of the two most significant watersheds in American constitutional history.

It is one of the ironic quirks of history that the viability and usefulness of nationalism and the territorial state are rapidly dissipating at precisely the time that the nation-state attained its highest number ( approximately 100 ).

Everyone is ready to grant the Persians their history, but almost no one is willing to acknowledge their present.

What is the history of criticism but the history of men attempting to make sense of the manifold elements in art that will not allow themselves to be reduced to a single philosophy or a single aesthetic theory??

It is different with his volume The Swedes And Their Chieftains ( Svenskarna och deras Hovdingar ), a history intended for the general reader and particularly suited for high school students.

Admirably written, it is a perfect introduction to Swedish history for readers of other countries.

All of this, I know, is recent history familiar to you.

But it is also the climax to one of the absorbing chapters in our current political history.

For paradigmatic history `` breaks '' rather than unfolds precisely when the movement is from order to disorder, and not from one order to a new order.

And it would seem that history is a witness to this truth.

The implicit assumption of this response is that history is reversible.

If many of the characters in contemporary novels appear to be the bloodless relations of characters in a case history it is because the novelist is often forgetful today that those things that we call character manifest themselves in surface behavior, that the ego is still the executive agency of personality, and that all we know of personality must be discerned through the ego.

It is to say rather, I believe, that he has brought to bear on the history, the traditions, and the lore of his region a critical, skeptical mind -- the same mind which has made of him an inveterate experimenter in literary form and technique.

His own testimony is that he has read very little in the history of the South, implying that what he knows of that history has come to him orally and that he knows the world around him primarily from his own unassisted observation.

His denials of extensive reading notwithstanding, it is no doubt safe to assume that he has spent time schooling himself in Southern history and that he has gained some acquaintance with the chief literary authors who have lived in the South or have written about the South.

Actually, you could wish for some passion, now and then, but when you look around the world and see the little volcanos of current history which partisan social passions have wrought, you are glad that in these pamphlets there is at least some civilized calm.

Here we may observe that at least one modern philosophy of history is built on the assumption that ideas are the primary objectives of the historian's research.

This is what was meant, above, by describing history as inferential.