Fact-checked by Grok 2 weeks ago

Past

The past is the set of all events, conditions, and states that have occurred before the current moment, distinguishing it from the present (what is now happening) and the (what will occur). This temporal category encompasses everything from personal experiences to cosmic occurrences predating the present, and it cannot be altered once it has transitioned into this status. In philosophy, the ontological status of the past has been intensely debated since antiquity, with key theories addressing whether it truly "exists" in any meaningful sense. Presentism, a prominent A-theory of time, posits that only present entities and events are real, denying any existence to the past and allowing reference to it only through present traces like memories, documents, or physical remnants. This view aligns with intuitive experiences of time's flow, where past events feel irretrievably gone, but it faces challenges in accounting for true statements about non-present objects, such as " was a philosopher." Conversely, , often associated with B-theories of time and relativity-inspired models, maintains that the past, present, and coexist equally within a static four-dimensional block, where all moments are equally real regardless of their temporal location. Proponents argue this resolves paradoxes of change by treating time like space, with past events "located" earlier in the timeline but no less existent. J.M.E. McTaggart's influential 1908 argument further complicates these views by claiming that any ascription of past, present, or predicates leads to contradiction, suggesting time itself—including the past—may be unreal as a fundamental feature of reality. Beyond metaphysics, the past serves as the raw material for disciplines like , where it is systematically reconstructed through evidence to illuminate human societies, cultures, and natural developments. Unlike the unmediated "past" as sheer occurrence, historical inquiry interprets it selectively, often revising narratives as new sources emerge, emphasizing its role in shaping , , and understanding of . In , the past manifests as grammatical tenses (e.g., or past perfect) to denote completed actions relative to the speaking time, facilitating precise communication about prior events. Overall, the past's significance lies in its inescapable influence on the present, from informing ethical decisions to grounding scientific models of and .

Core Concepts

Temporal Definition

The past encompasses all events, states, or conditions that have occurred prior to the present moment, forming a fundamental temporal category in human experience. This concept arises from the perception of time as a linear sequence, where moments are ordered from earlier to later, distinguishing the past as "earlier-than-now." The English word "past" derives from Middle English, appearing around the early 14th century as a variant of "passed," the past participle of "passen" meaning "to go by." It traces back to Old French "passé," the past participle of "passer" (to pass or go by), ultimately from Vulgar Latin "*passare" (to step or walk). As a noun denoting time gone by, it emerged around 1500, referring to preceding periods or elapsed history. Unlike the present, the past cannot be directly observed but is accessed indirectly through , historical records, and material artifacts. Personal and collective reconstruct past events via episodic and semantic recall, while external aids like cave paintings from at least 51,200 years ago, writing from around 3200 BCE, and archival collections (such as the ) preserve and transmit knowledge across generations. A core physical principle reinforcing the past's separation from the present is the , which imposes irreversibility on macroscopic processes through the second law of thermodynamics: in isolated systems increases over time, preventing reversion to prior low-entropy states.

Distinction from Present and Future

The past is fundamentally distinguished from the present and by its status as a of completed events that are fixed and unalterable. In contrast, the present involves ongoing processes and immediate experiences that remain subject to influence and change, while the represents anticipated possibilities and potential outcomes that have yet to unfold. This relational contrast underscores the past's role in providing a stable foundation for understanding , as events once part of the present become archived in once they conclude, shaping personal and collective identities without further modification. Perceptually, the separating the past from the present is marked by the subjective of "now," which functions as a fleeting divide rather than a precise instant. This "now" is often conceptualized as the specious present—a short temporal of about a few seconds that integrates recent sensory inputs, making them feel contemporaneous before they transition into remembered past. As moments elapse beyond this , they recede into the past, accessible only through recollection rather than direct , highlighting the fluid yet directional nature of human temporal awareness. Illustrative examples clarify these distinctions: the conclusion of in 1945 renders it an unequivocally past event, immune to revision and studied through historical records, unlike present-day occurrences such as international responses to in 2025, which evolve in real time, or future projections like widespread adoption of fusion energy by 2040, which remain speculative and adaptable. This unchangeability of the past fosters psychological tendencies toward romanticization, where individuals engage in by recalling past experiences more favorably than they occurred, often as a coping mechanism amid present uncertainties, or toward , an emotion arising from irrevocable choices that evokes about missed opportunities. The finality of the past thus amplifies these responses, as its immutability prevents direct resolution, though it can motivate adaptive reflections. This perceptual and emotional irreversibility also mirrors physical principles, where the past's unalterability ties to the second law of thermodynamics and entropy's inexorable increase.

Philosophical and Scientific Dimensions

Philosophical Perspectives

In , the nature of the past has been a central concern in metaphysics, particularly regarding its ontological status relative to the present and future. Two prominent theories dominate this discourse: presentism and . Presentism asserts that only present entities exist, rendering the past as a collection of former presents that no longer exist in any real sense. This view aligns with intuitive experiences where past events, such as historical figures or bygone occurrences, lack current spatial or temporal presence, emphasizing ontological parsimony by positing fewer entities overall. Eternalism, often associated with the block universe theory, counters this by maintaining that past, present, and future events coexist equally in a four-dimensional manifold, making the past ontologically real and no less existent than the present. Proponents argue this framework resolves tensions with , where simultaneity is observer-dependent, allowing non-present objects like ancient artifacts to persist timelessly. Unlike presentism, denies a privileged "now," viewing temporal divisions as perspectival rather than absolute. Early Christian philosopher Augustine of Hippo offered a subjective interpretation, proposing that the past exists only in the mind as a present memory, part of the soul's "distention" across recollection, attention to the present, and expectation of the future. In his Confessions, Augustine describes this as the mind measuring time internally, where the past is not an external reality but a psychological extension, bridging personal experience with divine eternity. Building on this, J.M.E. McTaggart's distinction between the A-series (events ordered as past, present, or future, capturing temporal passage) and B-series (events ordered by objective before/after relations, static and unchanging) underscores debates on time's reality, with the A-series implying the past's dynamic irreality if contradictory, while the B-series supports eternalism's fixed past. Philosophical debates further explore whether the past can be altered, often intersecting with and . In eternalist frameworks, the past's fixed ontological status precludes alteration, as any attempt to change it would contradict the block universe's consistency, aligning with deterministic views where past events causally necessitate the present. Presentism avoids this by denying the past's existence altogether, yet it raises issues for if future actions cannot retroactively influence non-existent priors. Thinkers like David Lewis argue that apparent paradoxes in altering the past resolve through commonplace failures, preserving determinism without undermining agency, though incompatibilists contend true requires an alterable past incompatible with strict causation.

Scientific Views

In , the concept of the past is observer-dependent, with no universal across space. Events accessible as "past" to an observer are confined to their past , which encompasses all points from which light or information could reach the observer, ensuring is preserved. For instance, distant events, such as those from stars light-years away, represent the past as observed, but their timing relative to the observer's "now" varies due to the . This framework, developed by in 1905, implies that the past is not a fixed global history but a relational structure shaped by an observer's position and motion. Thermodynamics provides a directional to time through the second law, which states that in an tends to increase, distinguishing past low-entropy states from future high-entropy ones. This irreversibility creates a perceived flow from order to disorder, with the early universe's representing the ultimate low-entropy origin approximately 13.8 billion years ago. The emerges because processes like or heat flow are statistically far more likely in the forward direction, making reconstruction of past states improbable without external intervention. In , the past of the is traced through its history, beginning with the and evidenced by the (CMB) , a uniform glow remnant from about 380,000 years after the . Observations from satellites like Planck confirm the 's age at 13.8 billion years, with the CMB serving as a snapshot of the hot, dense epoch when photons decoupled from matter. This relic , now cooled to 2.7 , maps early density fluctuations that seeded galaxy formation, providing empirical access to the 's formative past. Quantum mechanics generally treats past events as fixed and deterministic once measured, though debates on explore whether future measurements could influence past quantum states in interpretations like the . Such proposals aim to resolve nonlocality in entangled systems without hidden variables, but they remain speculative and lack experimental confirmation, with standard upholding the past's immutability through the collapse of the wave function. Seminal work by John Cramer in introduced retrocausal elements via advanced and retarded waves, yet consensus favors forward causation to avoid paradoxes.

Linguistic Usage

Grammatical Role

In , the refers to a used to indicate that an action, event, or state occurred or was true before the moment of speaking, typically marking completed or prior situations. This function is realized through morphology that locates the event in temporal relation to the present, distinguishing it from non-past forms. In English, the past tense manifests in several variants to convey nuances of completion, duration, or sequence. The , formed by verbs like "walked," denotes a completed action without emphasis on its ongoing nature. The past continuous, such as "was walking," highlights an action in progress at a specific past . The past perfect, exemplified by "had walked," signals an action completed before another past event, while the past perfect continuous, like "had been walking," combines prior completion with duration up to that point. English past tense formation involves regular and irregular patterns. Regular verbs add the suffix (or phonetic variants like /t/ or /d/) to the , as in "walk" becoming "walked," following a productive rule that applies consistently across most verbs. Irregular verbs, comprising about 200 in common use, deviate from this rule through stem changes, vowel alternations, or suppletive forms, such as "go" to "went" or "sing" to "sang," often preserving historical remnants of older Indo-European . These forms play a crucial role in narrative sequencing, where the establishes the primary timeline of events, and perfective variants like the past perfect manage flashbacks or anteriority to maintain chronological clarity. Cross-linguistically, past tense systems vary significantly in their integration with , which modulates how the event's internal structure is viewed. In , such as and , past tense verbs are inherently aspectual, with past tense marked by a suffix agreeing in and number, while is indicated by perfective or imperfective verb forms (e.g., Russian pročital "read [completely]" vs. čital "was reading"). Non-Indo-European languages like those in the family exhibit tense-aspect systems with multiple pre-stem markers for remoteness (near vs. distant past) and aspectual distinctions, such as the in (-li- prefix for completed or narrative past actions), with imperfective past progressive expressed through auxiliary constructions like -li-kuwa na- (e.g., "was [verb-ing]"), often encoded through agglutinative affixes that interact with . These variations underscore how past reference adapts to language-specific grammatical priorities, prioritizing event boundedness in or temporal distance in over English's primarily temporal focus. Additionally, the word "past" functions prepositionally to denote spatial or temporal progression beyond a point, as in "the house past ," though this usage is morphologically distinct from tense marking.

Idiomatic Expressions

In English, "past" functions as a preposition to indicate movement beyond or later than a specific point in space or time. For instance, it denotes passing by an object, as in "walk past the house," or a time slightly after an hour, such as "five past three," meaning 3:05. This usage emerged around as an extension of the form, signifying "beyond in time or position." Several idioms incorporate "past" to convey temporal or metaphorical ideas related to time's passage. The phrase "in the past" refers to former times or events that have occurred, as in "Technological advancements in the past have shaped modern society." Similarly, "past its prime" describes something that has exceeded its condition or usefulness, often applied to people, objects, or eras in decline, such as "The old theater is past its prime." Another common expression, "a blast from the past," evokes a sudden, nostalgic reminder of bygone days, like encountering an old song from one's . As an , "past" modifies nouns to indicate a previous state or role, exemplified by "past ," referring to a former holder of . Nominally, "the past" serves as a encompassing or prior events, as in "Historians study the past to understand the present." These forms highlight "past" as a versatile descriptor of what lies behind the present moment. The evolution of these uses traces back to the early , when "past" developed as a variant of the past "passed" from the "pass," borrowed from passer (to go by), ultimately from Latin passus (step). In , this shifted from denoting physical passage to abstract temporal concepts, laying the foundation for modern idiomatic expressions tied to progression beyond a point.

Fields of Study

Humanities Disciplines

The disciplines play a central role in reconstructing the past through the of records, artifacts, and cultural remnants, emphasizing and contextual understanding over purely empirical measurement. These fields—primarily , , and —employ interpretive methodologies to piece together experiences, societies, and transformations, drawing on written documents, oral accounts, and to illuminate how past events shaped contemporary identities. Unlike natural sciences, which focus on physical processes, humanities approaches prioritize the subjective and cultural dimensions of historical inquiry, fostering critical analysis of and meaning-making. History, as a core humanities discipline, involves the chronological study of past events and societies using primary documents such as letters, treaties, and chronicles, alongside oral traditions passed down through generations. Subfields like examine civilizations such as and through tablets and hieroglyphs, while medieval history reconstructs feudal systems via monastic records and court annals. Key methodologies include , which encompasses the techniques for researching and writing histories by synthesizing evidence into coherent narratives, and , a process of evaluating the , , and reliability of sources through inquiries into authorship, production context, and evidential value. For instance, during the , scholars like revived classical in works such as the History of the Florentine People, modeling modern historical writing on ancient Greek and Roman exemplars to interpret contemporary political changes. Archaeology complements history by focusing on material remains to reconstruct past human lifeways, particularly where written records are absent or incomplete. Practitioners employ systematic excavation techniques, such as gridding sites with datum points and screening soil to record artifacts in precise locations, to uncover tools, pottery, and structures that reveal daily activities and social structures. A fundamental method is stratigraphy, the analysis of layered soil deposits formed by natural and cultural processes, guided by the law of superposition—which posits that older layers lie beneath newer ones—to establish relative chronologies and event sequences. These approaches have enabled reconstructions of prehistoric settlements, such as those in the American Southwest, highlighting migration patterns and environmental adaptations. Anthropology, particularly its cultural and biological branches, investigates the past through ethnographic records and fossil evidence to understand human and societal diversity. , a method involving immersive fieldwork and , documents oral histories and to trace cultural continuities, as seen in studies of traditions in that link present practices to ancestral voyages. overlaps with in examining via skeletal fossils, analyzing traits like in early hominids from sites in to infer behavioral adaptations over millions of years. This interdisciplinary lens reveals how cultural practices, such as tool-making, intertwined with biological changes to shape .

Natural Sciences

In the natural sciences, the past is reconstructed through empirical analysis of physical evidence preserved in Earth's materials, such as rocks, fossils, and sediments, allowing to geological, , and climatic histories over billions of years. This approach relies on observable patterns and measurable processes governed by physical laws, distinguishing it from interpretive methods in other fields. Key disciplines like , , and paleoclimatology employ these records to understand long-term changes on , from its formation to recent environmental shifts. Geology examines the planet's 4.5-billion-year history primarily through stratified rock layers, known as strata, which record sequential events like sediment deposition and tectonic activity. , the theory that Earth's is divided into moving plates, explains how and mountain-building have reshaped the surface over eons, with evidence from matching rock formations across oceans. correlation, a comparing fossils—species with known short temporal ranges—in different rock sequences, enables precise alignment of strata across regions, establishing a global geological timescale. In , the fossil record provides direct evidence of evolutionary processes, supporting Charles Darwin's theory of , where environmental pressures favor heritable traits that enhance survival and reproduction over generations. This record traces species origins from ancient microbial life, with the oldest confirmed fossils dating to approximately 3.5 billion years ago in Western Australia's , indicating early photosynthetic bacteria. Transitional fossils, such as those documenting the diversification of life forms during the period, illustrate gradual adaptations driven by , filling key gaps in understanding biodiversity's deep-time development. Paleoclimatology reconstructs past climates using proxies like s and tree rings, which capture , , and atmospheric variations. s from , such as the Vostok core, reveal cyclical glacial-interglacial periods during the Pleistocene epoch (2.58 million to 11,700 years ago), with multiple ice ages marked by drops of up to 10°C and expanded polar ice sheets. Tree rings, analyzed via , extend records back thousands of years, showing narrower rings during cooler, drier Pleistocene-like conditions and correlating with data for hemispheric climate synchrony. Dating techniques are essential for assigning absolute ages to these records, with effective for organic materials up to about 50,000 years old by measuring the decay of isotopes. For deeper time scales, potassium-argon dating targets volcanic rocks, quantifying the decay of to argon-40 to date events from thousands to billions of years ago, such as early hominid sites or ancient eruptions. These methods, calibrated against known standards, provide chronological frameworks that integrate across disciplines, occasionally referencing broader cosmological timelines for Earth's formation context.

Cultural Representations

Literary and Artistic Depictions

In literature, the past is often depicted through motifs of and , allowing characters to revisit or reconstruct historical moments. ' The Time Machine (1895) introduces the concept of mechanical , enabling the protagonist to navigate temporal dimensions, though primarily projecting into the future while underscoring the past's role in shaping evolutionary decline and social critique. 's (1913–1927) explores nostalgia via mémoire involontaire, exemplified by the episode where a sensory trigger resurrects childhood memories, portraying the past as an enduring, emotionally charged presence amid modern fragmentation. Artistic representations in Romanticism frequently idealize the past as a source of heroic struggle and cultural unity. Eugène Delacroix's (1830) commemorates the , blending contemporary upheaval with classical allusions to evoke an idealized vision of freedom and from recent historical events. Personification of the past appears in literary works like Charles Dickens' (1843), where the manifests as a luminous figure guiding through suppressed memories of youth and lost opportunities, symbolizing reflection and the illuminating power of personal history. In film, the past exerts a haunting influence on present relationships, as seen in Asghar Farhadi's The Past (2013), where an Iranian expatriate's return to unravels lingering marital secrets and familial tensions, illustrating how unresolved destabilizes the future across cultural borders. Modern media extends these depictions through interactive simulations; the series (2007–present) immerses players in reconstructed historical eras, such as in (2018), using period-accurate architecture and events to blend factual pasts with fictional narratives of conflict, fostering experiential engagement with .

Societal Attitudes

Societal attitudes toward the past often manifest through , a sentimental longing for previous eras that idealizes them as simpler or superior. In cultures, this is commonly expressed as a yearning for the "good old days," evoking images of and before modern complexities arose. indicates that nostalgia can provide benefits such as increased self-continuity, meaning in life, , and social connectedness, particularly among vulnerable populations, by fostering a sense of continuity and emotional . However, it also carries risks, including mixed short-term effects on and potential negative impacts on mood the following day, which may exacerbate or hinder adaptation to the present. Cultural perceptions of the past vary significantly, influencing how societies value and engage with historical time. societies typically view time linearly, emphasizing progress from past to , which frames the past as a foundation for advancement. In contrast, many cultures, including the , perceive time as cyclical, with calendars like the Tzolk'in and Haab' representing recurring natural rhythms and renewals rather than irreversible progression. This cyclical outlook, shared among various Native American peoples, underscores interconnectedness with nature and ongoing cycles of existence, differing sharply from linear models by treating the past as eternally accessible rather than obsolete. Efforts to preserve the past reflect a societal commitment to safeguarding through institutions like museums and sites. The World Heritage program, established in 1972, has designated 1,248 sites worldwide as of 2025 for their outstanding cultural and natural value, promoting international cooperation to protect them from threats like and conflict. These initiatives foster public appreciation and education, yet they spark debates on "rewriting history," where revisionist interpretations challenge established narratives to incorporate marginalized perspectives or correct inaccuracies. Scholarly discussions emphasize that such revisions enhance historical accuracy without erasing the past, though they can provoke controversy over authenticity and selective memory. Contemporary societal attitudes grapple with reevaluating the past amid movements like "cancel culture," which involves publicly critiquing and distancing from historical figures due to actions now deemed unethical, such as colonialism or racism. In the United States, this has led to the removal of statues and renaming of institutions honoring such figures, viewed by some as accountability and by others as censorship. On a personal level, therapeutic techniques like reminiscence therapy encourage revisiting past experiences to process emotions and build resilience, enhancing psychological well-being by integrating historical self-understanding into present growth. These practices highlight a broader tension between honoring the past and adapting it to evolving ethical standards.

References

  1. [1]
    All History is Revisionist History
    What we call “the past” is just that: It's what happened at some point before now. Once it occurs, “the past” is gone forever—beyond repeating, ...
  2. [2]
    [PDF] The Unreality of Time - PhilPapers
    ELLIS MCTAGGART: THE UNREALITY OF TIME. Again, if we assert that the events M, N, 0, are all at different times, and are in that order, we assert that they.
  3. [3]
    [PDF] Presentism and Ontological Commitment∗ - Ted Sider
    Presentism is the doctrine that only the present is real. Since ordinary talk and thought are full of quantification over non-present objects, presentists are ...
  4. [4]
    [PDF] Philosophy of Time Eternalism vs. Presentism
    Sep 2, 2014 · Eternalism is the belief that all points in time (past, present, and future) are equally real. That which existed in the past, that which exists ...
  5. [5]
  6. [6]
    [PDF] Verb Tenses - present, future, past - Austin Peay State University
    Simple tenses include present (verb, verb+s), past (verb+ed), and future (will+verb). Perfect tenses use past participle with have/has or had. Progressive ...
  7. [7]
    Time, Tense & Physics | Issue 81 | Philosophy Now
    So there is nothing mysterious about 'The Past'; it is simply 'earlier-than-now' – and 'now' boils down to the time of the utterance. Other utterances at ...
  8. [8]
    Definition of PAST
    ### Summary of "Past" as a Noun (Time Before the Present)
  9. [9]
    Past - Etymology, Origin & Meaning
    Originating in the early 14th century from Old French "passen" meaning "go by," past means "gone by" or "belonging to a previous time," used as adjective ...
  10. [10]
    [PDF] History of memory artifacts - PhilArchive
    Abstract. Human biological memory systems have adapted to use technological artifacts to overcome some of the limitations of these systems.
  11. [11]
    The Arrow of Time | Internet Encyclopedia of Philosophy
    Many philosophers and physicists claim that time has an arrow that points from the past to the future.
  12. [12]
    The arrow of time, irreversibility and the second law of ...
    Nov 16, 2011 · The microscopic laws of physics are time reversible, a fact which is closely associated with the conservation of energy, a deep universal law.
  13. [13]
    [PDF] Putting Time in Perspective: A Valid, Reliable Individual-Differences ...
    We argue that the scale described in this article, the Zimbardo Time Perspective. Inventory (ZTPI), addresses the shortcomings of previous scales. It is easy to ...
  14. [14]
    The Development of Temporal Concepts: Linguistic Factors and ...
    A mature understanding of temporal markers involves a differentiation of the past and the future in terms of sequence, causal relations, distance to the present ...Missing: ongoing anticipated
  15. [15]
    The extended present: an informational context for perception
    Aug 26, 2021 · Several previous authors have proposed a kind of specious or subjective present moment that covers a few seconds of recent information.
  16. [16]
    Temporal Adjustments in the Evaluation of Events: The “Rosy View”
    The “rosy view” phenomenon is associated with an increase in the number of negative thoughts during the event which seem to be caused by distractions.
  17. [17]
    What We Regret Most … and Why - PMC - NIH
    Recent research on regret has pinpointed numerous cognitive consequences, including effects on blame, expectancies, superstition, suspicion, and ongoing ...
  18. [18]
    Entropy and the second law - Physics
    Dec 12, 1999 · The second law states disorder increases, and entropy measures disorder. In irreversible processes, entropy always increases.
  19. [19]
    Presentism - Stanford Encyclopedia of Philosophy
    Jan 22, 2018 · Presentism is the view that only present things exist. So understood, presentism is primarily an ontological doctrine; it's a view about what exists, ...
  20. [20]
    Time (Stanford Encyclopedia of Philosophy)
    ### Definition and Description of "The Past" in Philosophy of Time
  21. [21]
    Augustine of Hippo - Stanford Encyclopedia of Philosophy
    Sep 25, 2019 · Here Augustine says that the human mind has been created by God in such a way as to be “connected” to intelligible reality “from below” ( ...
  22. [22]
    Time Travel - Stanford Encyclopedia of Philosophy
    Nov 14, 2013 · Eternalism is the view that past and future times, objects and events are just as real as the present time and present events and objects.
  23. [23]
    GP-B — Einstein's Spacetime - Gravity Probe B
    This is the basis of Einstein's theory of special relativity ("special" refers to the restriction to uniform motion).<|control11|><|separator|>
  24. [24]
    spacetime_light_cone.html - UNLV Physics
    The past light cone is all of spacetime events that could affect the observer; the future light cone is all of spacetime events that the observer could affect.
  25. [25]
    Causality and the Light Cone
    The cone consists of the points in the future that can be reached by light emitted by the observer plus the points in the past from which light could be ...
  26. [26]
    Thermodynamic Asymmetry in Time
    Nov 15, 2001 · Coupled with expansion, various processes will contribute to entropy increase, e.g., energy will flow from the “hot” radiation to the “cool” ...2. The Problem Of The... · 2.3 Cosmology · 3. The Problem Of The...
  27. [27]
    [PDF] The Arrow of Time
    entropy increases throughout, as the system progresses from order to disorder. When- ever we disturb the universe, we tend to increase its entropy. NATURE'S ...
  28. [28]
    Arrows of Time - UCSB Physics
    (with M. Gell-Mann) The thermodynamic arrow of time is associated with the increase of a globally defined entropy. An entropy is defined by a coarse graining.Time Symmetry And Asymmetry... · Entropy Of Classical... · The Physics Of Now (132)
  29. [29]
    Cosmic History - NASA Science
    Oct 22, 2024 · Around 13.8 billion years ago, the universe expanded faster than the speed of light for a fraction of a second, a period called cosmic inflation.
  30. [30]
    Cosmic Microwave Background | Center for Astrophysics | Harvard ...
    The cosmic microwave background is a snapshot of the oldest light in our universe, from when the cosmos was just 380,000 years old. The colors of the map ...
  31. [31]
    How old is the universe? - StarChild - NASA
    Jul 21, 2023 · UPDATE! Measurements made by NASA's WMAP spacecraft have shown that the universe is 13.7 billion years old, plus or minus about 130,000 years.
  32. [32]
    Retrocausality in Quantum Mechanics
    Jun 3, 2019 · This entry presents an overview of retrocausal approaches to the interpretation of quantum theory, the main motivations for adopting this approach.
  33. [33]
    Tense - Bernard Comrie - Google Books
    Jun 6, 1985 · Bernard Comrie defines tense as the grammaticalisation of location in time. In this textbook he introduces readers to the range of variation found in tense ...
  34. [34]
    PAST TENSE | definition in the Cambridge English Dictionary
    used to describe verb forms in many languages used for actions that have now finished. It is used by some people to refer to the past simple in English.
  35. [35]
    Past tense | LearnEnglish - British Council
    There are four past tense forms in English. We use these forms: He worked at McDonald's. He had worked there since July. He was working at McDonald's.
  36. [36]
    Discursive role of past tenses : a text analysis - ResearchGate
    Aug 7, 2025 · The article discusses the meaning and usage of the principal past tense forms in English from a discursive perspective.<|control11|><|separator|>
  37. [37]
    Chapter Perfective/Imperfective Aspect - WALS Online
    The distinction between imperfective and perfective plays an important role in many verb systems and is commonly signalled by morphological means.
  38. [38]
    Tense and Aspect in Bantu - Derek Nurse - Oxford University Press
    Derek Nurse looks at variations in the form and function of tense and aspect in Bantu, a branch of Niger-Congo, the world's largest language phylum.
  39. [39]
  40. [40]
  41. [41]
  42. [42]
    Geologic Time: Age of the Earth - USGS Publications Warehouse
    Jul 9, 2007 · The ages measured for Earth's oldest rocks and oldest crystals show that the Earth is at least 4.3 billion years in age but do not reveal the exact age of ...
  43. [43]
    Historical perspective [This Dynamic Earth, USGS]
    Jul 11, 2025 · The theory of plate tectonics states that the Earth's outermost layer is fragmented into a dozen or more large and small plates that are moving relative to one ...
  44. [44]
    Geologic Time: Correlation Chart - USGS Publications Warehouse
    Jul 28, 1997 · Correlation chart. These sections are typical of the ones geologists prepare when studying the relationships of layers of rocks (beds) throughout a region.
  45. [45]
    Natural Selection, Genetic Drift, and Gene Flow Do Not Act in ...
    As Charles Darwin (1859) argued in On the Origin of Species, if the following conditions are met, natural selection must occur: There is variation among ...
  46. [46]
    Early Archean (3.3-Billion to 3.5-Billion-Year-Old) Microfossils from ...
    The cell types detected suggest that cyanobacteria, and therefore oxygen-producing photosynthesis, may have been extant as early as 3.3 billion to 3.5 billion ...
  47. [47]
    Paleo Data Search | Study
    Oct 10, 2018 · Here we report a bidecadally-resolved New Zealand kauri (Agathis australis) tree-ring sequence spanning two millennia that preserves a record of ...
  48. [48]
    Geologic Time: Radiometric Time Scale
    Jun 13, 2001 · The radiocarbon clock has become an extremely useful and ... dating events that have taken place only within the past 50,000 years.Missing: range | Show results with:range
  49. [49]
    [PDF] The Mechanics of Temporality in H.G. Wells' The Time Machine
    May 10, 2012 · Viewing The Time Machine as a whole, we see that the entire story is contained in one large analepse, the narrator looking back on those dinner.
  50. [50]
    In Search of Lost Community: The Literary Image between “Proust ...
    Once viewed through the gauze of the novelist's hermetic inclinations, In Search of Lost Time might read as recoiling against this emotional inurement that ...
  51. [51]
    Famous Romanticism Paintings - The Best Examples of Romantic ...
    Feb 9, 2022 · Eugène Delacroix is considered the most representative French Romanticism painter. Delacroix's masterpiece, Liberty Leading the People, ...
  52. [52]
    A Christmas Carol — Symbols - CliffsNotes
    A Christmas Carol. Symbols. Charles Dickens. Cite This Page. Download PDF ... Light shines from the head of the Ghost of Christmas Past. For Scrooge, this ...
  53. [53]
    The Past movie review & film summary (2013) - Roger Ebert
    Rating 4/4 · Review by Godfrey CheshireDec 20, 2013 · Of the three main adult characters in “The Past,” one is Iranian, one French and one Arab. While it wouldn't be accurate to that these cultural ...
  54. [54]
    “History Is Our Playground”: Action and Authenticity in Assassin's ...
    Aug 23, 2019 · The narrative framing device of Assassin's Creed is one in which two shadowy organizations, the Templar and the Assassins—both highly ...
  55. [55]
    The Good Old Days - SAPIENS – Anthropology Magazine
    Jan 5, 2017 · The Good Old Days. The craving for simplicity comes from nostalgia for simpler times. But it is harmful to remember the past as “simple." By ...
  56. [56]
    Full article: Benefits of nostalgia in vulnerable populations
    For them, nostalgia (compared to control) significantly increased self-continuity, meaning in life, self-esteem, and social connectedness, and did not ...
  57. [57]
    Nostalgia and Well-Being in Daily Life: An Ecological Validity ...
    Lagged analyses showed that state nostalgia had mixed effects on well-being at a later moment that day and negative effects on well-being on the following day.
  58. [58]
    How Different Cultures Understand Time | The LOTE Agency
    Cultures perceive time as linear (Western), cyclical (some ancient cultures), or procedural (some Aboriginal groups). Monochronic cultures focus on time as a ...
  59. [59]
    How the Maya Kept Time - JSTOR Daily
    Jan 2, 2022 · The Maya used two cyclical calendars, the tzolk’in (260 days) and ja’ab’ (365 days), and a linear Long Count, with a 52-year Calendar Round.
  60. [60]
    Cyclical views of time - Mexicolore
    Many Native American peoples, and peoples elsewhere in the world, have a cyclical view of time in which a defined period of time ends and a new one begins.
  61. [61]
    World Heritage | UNESCO
    UNESCO seeks to encourage the identification, protection and preservation of cultural and natural heritage around the world considered to be of outstanding ...UNESCO Sites Navigator · World Heritage Committee 2024
  62. [62]
    [PDF] Historical Revisionism: Revising or Rewriting - Liberty University
    Nov 28, 2022 · A scholarly and reliable historiography as the study of the representation of history leads to trustworthy metanarratives that are accurate to ...
  63. [63]
    Americans and 'Cancel Culture': Where Some See Calls for ...
    May 19, 2021 · This report focuses on American adults' perceptions of cancel culture and, more generally, calling out others on social media.
  64. [64]
    Reminiscence Therapy vs. Life Review Therapy: A Quick Guide
    May 23, 2023 · Reminiscence therapy involves recalling personal memories to enhance psychological wellbeing, particularly in older adults.