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Uniformitarianism, also known as the Doctrine of Uniformity or the Uniformitarian Principle, is the assumption that the same natural laws and processes that operate in our present-day scientific observations have always operated in the universe in the past and apply everywhere in the universe., "''The assumption of spatial and temporal invariance of natural laws is by no means unique to geology since it amounts to a warrant for inductive inference'' which, as Bacon showed nearly four hundred years ago, is ''the basic mode of reasoning in empirical science. Without assuming this spatial and temporal invariance, we have no basis for extrapolating from the known to the unknown'' and, therefore, no way of reaching general conclusions from a finite number of observations." It refers to invariance in the
metaphysical Metaphysics is the branch of philosophy that studies the fundamental nature of reality, the first principles of being, identity and change, space and time, causality, necessity, and possibility. It includes questions about the nature of conscio ...
principles underpinning science, such as the constancy of cause and effect throughout space-time, but has also been used to describe spatiotemporal invariance of
physical laws Scientific laws or laws of science are statements, based on repeated experiments or observations, that describe or predict a range of natural phenomena. The term ''law'' has diverse usage in many cases (approximate, accurate, broad, or narrow) a ...
. Though an unprovable
postulate An axiom, postulate, or assumption is a statement that is taken to be true, to serve as a premise or starting point for further reasoning and arguments. The word comes from the Ancient Greek word (), meaning 'that which is thought worthy or f ...
that cannot be verified using the scientific method, some consider that uniformitarianism should be a required
first principle In philosophy and science, a first principle is a basic proposition or assumption that cannot be deduced from any other proposition or assumption. First principles in philosophy are from First Cause attitudes and taught by Aristotelians, and nua ...
in scientific research., "''Uniformity is an unprovable postulate'' justified, or indeed required, on two grounds. First, nothing in our incomplete but extensive knowledge of history disagrees with it. Second, ''only with this postulate is a rational interpretation of history possible'', and we are justified in seeking—as scientists we must seek—such a rational interpretation." Other scientists disagree and consider that nature is not absolutely uniform, even though it does exhibit certain regularities. In
geology Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...
, uniformitarianism has included the gradualistic concept that "the present is the key to the past" and that geological events occur at the same rate now as they have always done, though many modern geologists no longer hold to a strict gradualism. Coined by
William Whewell William Whewell ( ; 24 May 17946 March 1866) was an English polymath, scientist, Anglican priest, philosopher, theologian, and historian of science. He was Master of Trinity College, Cambridge. In his time as a student there, he achieved dist ...
, it was originally proposed in contrast to
catastrophism In geology, catastrophism theorises that the Earth has largely been shaped by sudden, short-lived, violent events, possibly worldwide in scope. This contrasts with uniformitarianism (sometimes called gradualism), according to which slow increment ...
by British naturalists in the late 18th century, starting with the work of the
geologist A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, earth science, or geophysics, althou ...
James Hutton James Hutton (; 3 June O.S.172614 June 1726 New Style. – 26 March 1797) was a Scottish geologist, agriculturalist, chemical manufacturer, naturalist and physician. Often referred to as the father of modern geology, he played a key role i ...
in his many books including ''
Theory of the Earth ''Theory of the Earth'' was a publication by James Hutton which laid the foundations for geology. In it he showed that the Earth is the product of natural forces. What could be seen happening today, over long periods of time, could produce what ...
''. Hutton's work was later refined by scientist
John Playfair John Playfair FRSE, FRS (10 March 1748 – 20 July 1819) was a Church of Scotland minister, remembered as a scientist and mathematician, and a professor of natural philosophy at the University of Edinburgh. He is best known for his book ''Illu ...
and popularised by geologist
Charles Lyell Sir Charles Lyell, 1st Baronet, (14 November 1797 – 22 February 1875) was a Scottish geologist who demonstrated the power of known natural causes in explaining the earth's history. He is best known as the author of ''Principles of Geolo ...
's ''
Principles of Geology ''Principles of Geology: Being an Attempt to Explain the Former Changes of the Earth's Surface, by Reference to Causes Now in Operation'' is a book by the Scottish geologist Charles Lyell that was first published in 3 volumes from 1830–1833. Ly ...
'' in 1830. Today, Earth's history is considered to have been a slow, gradual process, punctuated by occasional natural catastrophic events.


History


18th century

The earlier conceptions likely had little influence on 18th-century European geological explanations for the formation of Earth.
Abraham Gottlob Werner Abraham Gottlob Werner (; 25 September 174930 June 1817) was a German geologist who set out an early theory about the stratification of the Earth's crust and propounded a history of the Earth that came to be known as Neptunism. While most tenet ...
(1749–1817) proposed
Neptunism Neptunism is a superseded scientific theory of geology proposed by Abraham Gottlob Werner (1749–1817) in the late 18th century, proposing that rocks formed from the crystallisation of minerals in the early Earth's oceans. The theory took its na ...
, where
strata In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as ei ...
represented deposits from shrinking seas
precipitated In an aqueous solution, precipitation is the process of transforming a dissolved substance into an insoluble solid from a super-saturated solution. The solid formed is called the precipitate. In case of an inorganic chemical reaction leading ...
onto primordial rocks such as
granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...
. In 1785
James Hutton James Hutton (; 3 June O.S.172614 June 1726 New Style. – 26 March 1797) was a Scottish geologist, agriculturalist, chemical manufacturer, naturalist and physician. Often referred to as the father of modern geology, he played a key role i ...
proposed an opposing, self-maintaining infinite cycle based on natural history and not on the
Biblical The Bible (from Koine Greek , , 'the books') is a collection of religious texts or scriptures that are held to be sacred in Christianity, Judaism, Samaritanism, and many other religions. The Bible is an anthologya compilation of texts of a ...
account. Hutton then sought evidence to support his idea that there must have been repeated cycles, each involving deposition on the
seabed The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as 'seabeds'. The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...
, uplift with tilting and
erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...
, and then moving undersea again for further layers to be deposited. At
Glen Tilt Glen Tilt (Scottish Gaelic: Gleann Teilt) is a glen in the extreme north of Perthshire, Scotland. Beginning at the confines of Aberdeenshire, it follows a South-westerly direction excepting for the last 4 miles, when it runs due south to Blair ...
in the Cairngorm mountains he found granite penetrating
metamorphic Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causin ...
schist Schist ( ) is a medium-grained metamorphic rock showing pronounced schistosity. This means that the rock is composed of mineral grains easily seen with a low-power hand lens, oriented in such a way that the rock is easily split into thin flakes o ...
s, in a way which indicated to him that the presumed primordial rock had been
molten Melting, or fusion, is a physical process that results in the phase transition of a substance from a solid to a liquid. This occurs when the internal energy of the solid increases, typically by the application of heat or pressure, which inc ...
after the strata had formed. Review of Repcheck's ''The Man Who Found Time'' He had read about angular unconformities as interpreted by Neptunists, and found an
unconformity An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval o ...
at
Jedburgh Jedburgh (; gd, Deadard; sco, Jeddart or ) is a town and former royal burgh in the Scottish Borders and the traditional county town of the historic county of Roxburghshire, the name of which was randomly chosen for Operation Jedburgh in su ...
where layers of
greywacke Greywacke or graywacke (German ''grauwacke'', signifying a grey, earthy rock) is a variety of sandstone generally characterized by its hardness, dark color, and poorly sorted angular grains of quartz, feldspar, and small rock fragments or lit ...
in the lower layers of the cliff face have been tilted almost vertically before being eroded to form a level plane, under horizontal layers of
Old Red Sandstone The Old Red Sandstone is an assemblage of rocks in the North Atlantic region largely of Devonian age. It extends in the east across Great Britain, Ireland and Norway, and in the west along the northeastern seaboard of North America. It also exte ...
. In the spring of 1788 he took a boat trip along the
Berwickshire Berwickshire ( gd, Siorrachd Bhearaig) is a historic county, registration county and lieutenancy area in south-eastern Scotland, on the English border. Berwickshire County Council existed from 1890 until 1975, when the area became part of th ...
coast with
John Playfair John Playfair FRSE, FRS (10 March 1748 – 20 July 1819) was a Church of Scotland minister, remembered as a scientist and mathematician, and a professor of natural philosophy at the University of Edinburgh. He is best known for his book ''Illu ...
and the geologist Sir James Hall, and found a dramatic unconformity showing the same sequence at
Siccar Point Siccar Point is a rocky promontory in the county of Berwickshire on the east coast of Scotland. It is famous in the history of geology for Hutton's Unconformity found in 1788, which James Hutton regarded as conclusive proof of his uniformitar ...
. Playfair later recalled that "the mind seemed to grow giddy by looking so far into the abyss of time", and Hutton concluded a 1788 paper he presented at the
Royal Society of Edinburgh The Royal Society of Edinburgh is Scotland's national academy of science and letters. It is a registered charity that operates on a wholly independent and non-partisan basis and provides public benefit throughout Scotland. It was established i ...
, later rewritten as a book, with the phrase "we find no vestige of a beginning, no prospect of an end". Both Playfair and Hall wrote their own books on the theory, and for decades robust debate continued between Hutton's supporters and the Neptunists.
Georges Cuvier Jean Léopold Nicolas Frédéric, Baron Cuvier (; 23 August 1769 – 13 May 1832), known as Georges Cuvier, was a French natural history, naturalist and zoology, zoologist, sometimes referred to as the "founding father of paleontology". Cuvier ...
's paleontological work in the 1790s, which established the reality of
extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
, explained this by local catastrophes, after which other fixed species repopulated the affected areas. In Britain, geologists adapted this idea into " diluvial theory" which proposed repeated worldwide annihilation and creation of new fixed species adapted to a changed environment, initially identifying the most recent catastrophe as the
biblical flood The Genesis flood narrative (chapters 6–9 of the Book of Genesis) is the Hebrew version of the universal flood myth. It tells of God's decision to return the universe to its pre- creation state of watery chaos and remake it through the micro ...
.


19th century

From 1830 to 1833
Charles Lyell Sir Charles Lyell, 1st Baronet, (14 November 1797 – 22 February 1875) was a Scottish geologist who demonstrated the power of known natural causes in explaining the earth's history. He is best known as the author of ''Principles of Geolo ...
's multi-volume ''
Principles of Geology ''Principles of Geology: Being an Attempt to Explain the Former Changes of the Earth's Surface, by Reference to Causes Now in Operation'' is a book by the Scottish geologist Charles Lyell that was first published in 3 volumes from 1830–1833. Ly ...
'' was published. The work's subtitle was "An attempt to explain the former changes of the Earth's surface by reference to causes now in operation". He drew his explanations from field studies conducted directly before he went to work on the founding geology text, and developed Hutton's idea that the earth was shaped entirely by slow-moving forces still in operation today, acting over a very long period of time. The terms ''uniformitarianism'' for this idea, and ''
catastrophism In geology, catastrophism theorises that the Earth has largely been shaped by sudden, short-lived, violent events, possibly worldwide in scope. This contrasts with uniformitarianism (sometimes called gradualism), according to which slow increment ...
'' for the opposing viewpoint, was coined by
William Whewell William Whewell ( ; 24 May 17946 March 1866) was an English polymath, scientist, Anglican priest, philosopher, theologian, and historian of science. He was Master of Trinity College, Cambridge. In his time as a student there, he achieved dist ...
in a review of Lyell's book. ''Principles of Geology'' was the most influential geological work in the middle of the 19th century.


Systems of inorganic earth history

Geoscientists support diverse systems of Earth history, the nature of which rests on a certain mixture of views about the process, control, rate, and state which are preferred. Because geologists and geomorphologists tend to adopt opposite views over process, rate, and state in the inorganic world, there are eight different systems of beliefs in the development of the terrestrial sphere. All geoscientists stand by the principle of uniformity of law. Most, but not all, are directed by the principle of simplicity. All make definite assertions about the quality of rate and state in the inorganic realm.


Lyell

According to
Reijer Hooykaas Reijer Hooykaas (1 August 1906 in Schoonhoven – 4 January 1994 in Zeist) was a Dutch historian of science. He along with Eduard Jan Dijksterhuis were pioneers in professionalizing the history of science in the Netherlands. Hooykaas gave the ...
(1963), Lyell's uniformitarianism is a family of four related propositions, not a single idea: * Uniformity of law – the laws of nature are constant across time and space. * Uniformity of methodology – the appropriate hypotheses for explaining the geological past are those with analogy today. * Uniformity of kind – past and present causes are all of the same kind, have the same energy, and produce the same effects. * Uniformity of degree – geological circumstances have remained the same over time. None of these connotations requires another, and they are not all equally inferred by uniformitarians.
Gould Gould may refer to: People * Gould (name), a surname Places United States * Gould, Arkansas, a city * Gould, Colorado, an unincorporated community * Gould, Ohio, an unincorporated community * Gould, Oklahoma, a town * Gould, West Virginia, a ...
explained Lyell's propositions in ''
Time's Arrow, Time's Cycle ''Time's Arrow, Time's Cycle: Myth and Metaphor in the Discovery of Geological Time'' is a 1987 history of geology by the paleontologist Stephen Jay Gould, in which the author offers a historical account of the conceptualization of Deep Time an ...
'' (1987), stating that Lyell conflated two different types of propositions: a pair of ''methodological assumptions'' with a pair of ''substantive hypotheses''. The four together make up Lyell's uniformitarianism.


=Methodological assumptions

= The two methodological assumptions below are accepted to be true by the majority of scientists and geologists. Gould claims that these philosophical propositions must be assumed before you can proceed as a scientist doing science. "You cannot go to a rocky outcrop and observe either the constancy of nature's laws or the working of unknown processes. It works the other way around." You first assume these propositions and "then you go to the outcrop.". "You first assume." :* Uniformity of law across time and space: Natural laws are constant across space and time. ::The axiom of uniformity of law , "''Making inferences about the past is wrapped up in the difference between studying the observable and the unobservable.'' In the observable, erroneous beliefs can be proven wrong and be inductively corrected by other observations. This is Popper's principle of
falsifiability Falsifiability is a standard of evaluation of scientific theories and hypotheses that was introduced by the philosopher of science Karl Popper in his book ''The Logic of Scientific Discovery'' (1934). He proposed it as the cornerstone of a sol ...
. However, ''past processes are not observable by their very nature.'' Therefore, the invariance of nature's laws must be assumed to come to conclusions about the past.''"
is necessary in order for scientists to extrapolate (by inductive inference) into the unobservable past. The constancy of natural laws must be assumed in the study of the past; else we cannot meaningfully study it. :* Uniformity of process across time and space: Natural processes are constant across time and space. ::Though similar to uniformity of law, this second ''a priori'' assumption, shared by the vast majority of scientists, deals with geological causes, not physicochemical laws. The past is to be explained by processes acting currently in time and space rather than inventing extra esoteric or unknown processes ''without good reason'', otherwise known as parsimony or
Occam's razor Occam's razor, Ockham's razor, or Ocham's razor ( la, novacula Occami), also known as the principle of parsimony or the law of parsimony ( la, lex parsimoniae), is the problem-solving principle that "entities should not be multiplied beyond neces ...
.


=Substantive hypotheses

= The substantive hypotheses were controversial and, in some cases, accepted by few. These hypotheses are judged true or false on empirical grounds through scientific observation and repeated experimental data. This is in contrast with the previous two philosophical assumptions that come before one can do science and so cannot be tested or falsified by science. :* Uniformity of rate across time and space: Change is typically slow, steady, and gradual. ::Uniformity of rate (or
gradualism Gradualism, from the Latin ''gradus'' ("step"), is a hypothesis, a theory or a tenet assuming that change comes about gradually or that variation is gradual in nature and happens over time as opposed to in large steps. Uniformitarianism, incrementa ...
) is what most people (including geologists) think of when they hear the word "uniformitarianism," confusing this hypothesis with the entire definition. As late as 1990, Lemon, in his textbook of stratigraphy, affirmed that "The uniformitarian view of earth history held that all geologic processes proceed continuously and at a very slow pace." ::Gould explained Hutton's view of uniformity of rate; mountain ranges or grand canyons are built by the accumulation of nearly insensible changes added up through vast time. Some major events such as floods, earthquakes, and eruptions, do occur. But these catastrophes are strictly local. They neither occurred in the past nor shall happen in the future, at any greater frequency or extent than they display at present. In particular, the whole earth is never convulsed at once. :* Uniformity of state across time and space: Change is evenly distributed throughout space and time. ::The uniformity of state hypothesis implies that throughout the history of our earth there is no progress in any inexorable direction. The planet has almost always looked and behaved as it does now. Change is continuous but leads nowhere. The earth is in balance: a dynamic
steady state In systems theory, a system or a Process theory, process is in a steady state if the variables (called state variables) which define the behavior of the system or the process are unchanging in time. In continuous time, this means that for those p ...
.


20th century

Stephen Jay Gould Stephen Jay Gould (; September 10, 1941 – May 20, 2002) was an American paleontologist, evolutionary biologist, and historian of science. He was one of the most influential and widely read authors of popular science of his generation. Gould sp ...
's first scientific paper, "Is uniformitarianism necessary?" (1965), reduced these four assumptions to two. He dismissed the first principle, which asserted spatial and temporal invariance of natural laws, as no longer an issue of debate. He rejected the third (uniformity of rate) as an unjustified limitation on scientific inquiry, as it constrains past geologic rates and conditions to those of the present. So, Lyell's uniformitarianism was deemed unnecessary. Uniformitarianism was proposed in contrast to
catastrophism In geology, catastrophism theorises that the Earth has largely been shaped by sudden, short-lived, violent events, possibly worldwide in scope. This contrasts with uniformitarianism (sometimes called gradualism), according to which slow increment ...
, which states that the distant past "consisted of epochs of paroxysmal and catastrophic action interposed between periods of comparative tranquility" Especially in the late 19th and early 20th centuries, most geologists took this interpretation to mean that catastrophic events are not important in geologic time; one example of this is the debate of the formation of the
Channeled Scablands The Channeled Scablands are a relatively barren and soil-free region of interconnected relict and dry flood channels, coulees and cataracts eroded into Palouse loess and the typically flat-lying basalt flows that remain after cataclysmic floods ...
due to the catastrophic
Missoula Missoula ( ; fla, label=Salish language, Séliš, Nłʔay, lit=Place of the Small Bull Trout, script=Latn; kut, Tuhuⱡnana, script=Latn) is a city in the U.S. state of Montana; it is the county seat of Missoula County, Montana, Missoula Cou ...
glacial outburst floods. An important result of this debate and others was the re-clarification that, while the same principles operate in geologic time, catastrophic events that are infrequent on human time-scales can have important consequences in geologic history. Derek Ager has noted that "geologists do not deny uniformitarianism in its true sense, that is to say, of interpreting the past by means of the processes that are seen going on at the present day, so long as we remember that the periodic catastrophe is one of those processes. Those periodic catastrophes make more showing in the stratigraphical record than we have hitherto assumed." Even
Charles Lyell Sir Charles Lyell, 1st Baronet, (14 November 1797 – 22 February 1875) was a Scottish geologist who demonstrated the power of known natural causes in explaining the earth's history. He is best known as the author of ''Principles of Geolo ...
thought that ordinary geological processes would cause
Niagara Falls Niagara Falls () is a group of three waterfalls at the southern end of Niagara Gorge, spanning the border between the province of Ontario in Canada and the state of New York in the United States. The largest of the three is Horseshoe Falls, ...
to move upstream to
Lake Erie Lake Erie ( "eerie") is the fourth largest lake by surface area of the five Great Lakes in North America and the eleventh-largest globally. It is the southernmost, shallowest, and smallest by volume of the Great Lakes and therefore also has t ...
within 10,000 years, leading to catastrophic flooding of a large part of North America. Modern geologists do not apply uniformitarianism in the same way as Lyell. They question if rates of processes were uniform through time and only those values measured during the
history of geology The history of geology is concerned with the development of the natural science of geology. Geology is the scientific study of the origin, history, and structure of Earth. Antiquity Some of the first geological thoughts were about the ori ...
are to be accepted. The present may not be a long enough key to penetrating the deep lock of the past. Geologic processes may have been active at different rates in the past that humans have not observed. "By force of popularity, uniformity of rate has persisted to our present day. For more than a century, Lyell's rhetoric conflating axiom with hypotheses has descended in unmodified form. Many geologists have been stifled by the belief that proper methodology includes an a priori commitment to gradual change, and by a preference for explaining large-scale phenomena as the concatenation of innumerable tiny changes." The current consensus is that
Earth's history The history of Earth concerns the development of planet Earth from its formation to the present day. Nearly all branches of natural science have contributed to understanding of the main events of Earth's past, characterized by constant geologic ...
is a slow, gradual process punctuated by occasional natural catastrophic events that have affected Earth and its inhabitants. In practice it is reduced from Lyell's conflation, or blending, to simply the two philosophical assumptions. This is also known as the principle of geological actualism, which states that all past geological action was like all present geological action. The principle of
actualism In analytic philosophy, actualism is the view that everything there ''is'' (i.e., everything that has ''being'', in the broadest sense) is wiktionary:actual, actual. Another phrasing of the thesis is that the domain of discourse, domain of Range o ...
is the cornerstone of
paleoecology Paleoecology (also spelled palaeoecology) is the study of interactions between organisms and/or interactions between organisms and their environments across geologic timescales. As a discipline, paleoecology interacts with, depends on and informs ...
.


Social sciences

Uniformitarianism has also been applied in
historical linguistics Historical linguistics, also termed diachronic linguistics, is the scientific study of language change over time. Principal concerns of historical linguistics include: # to describe and account for observed changes in particular languages # ...
, where it is considered a foundational principle of the field. Linguist Donald Ringe gives the following definition:


See also

*
Conservation law In physics, a conservation law states that a particular measurable property of an isolated physical system does not change as the system evolves over time. Exact conservation laws include conservation of energy, conservation of linear momentum, c ...
*
Noether's theorem Noether's theorem or Noether's first theorem states that every differentiable symmetry of the action of a physical system with conservative forces has a corresponding conservation law. The theorem was proven by mathematician Emmy Noether in ...
* Law of universal gravitation *
Astronomical spectroscopy Astronomical spectroscopy is the study of astronomy using the techniques of spectroscopy to measure the spectrum of electromagnetic radiation, including visible light, ultraviolet, X-ray, infrared and radio waves that radiate from stars and othe ...
*
Cosmological principle In modern physical cosmology, the cosmological principle is the notion that the spatial distribution of matter in the universe is homogeneous and isotropic when viewed on a large enough scale, since the forces are expected to act uniformly throu ...
*
History of paleontology The history of paleontology traces the history of the effort to understand the history of life on Earth by studying the fossil record left behind by living organisms. Since it is concerned with understanding living organisms of the past, paleon ...
*
Paradigm shift A paradigm shift, a concept brought into the common lexicon by the American physicist and philosopher Thomas Kuhn, is a fundamental change in the basic concepts and experimental practices of a scientific discipline. Even though Kuhn restricted t ...
*
Physical constant A physical constant, sometimes fundamental physical constant or universal constant, is a physical quantity that is generally believed to be both universal in nature and have constant value in time. It is contrasted with a mathematical constant, ...
*
Physical cosmology Physical cosmology is a branch of cosmology concerned with the study of cosmological models. A cosmological model, or simply cosmology, provides a description of the largest-scale structures and dynamics of the universe and allows study of f ...
*
Scientific consensus Scientific consensus is the generally held judgment, position, and opinion of the majority or the supermajority of scientists in a particular field of study at any particular time. Consensus is achieved through scholarly communication at confe ...
* Time-variation of fundamental constants


Notes


References

* * * * * * * * ;Web * *


External links


Uniformitarianism
a
Physical Geography
*

{{Authority control Metatheory of science Evolution Geological history of Earth History of Earth science Epistemology of science