時間

時間（英語：time）是一種尺度，在物理定義是標量，藉著時間，事件發生之先後可以按過去-現在-未來之序列得以確定（時間點/時刻，point in time/instant），也可以衡量事件持續的期間以及事件之間和間隔長短（時間段，duration）^[1]^[2]。

在閔考斯基時空中，時間是除了空間三個維度以外的第四維度^[3]。長久以來，時間一直是宗教、哲學及科學領域的研究主題之一，但學者們尚且無法為時間找到一個可以適用於各領域、具有一致性且又不循環的定義^[4]。在商業、工業、體育、科學及表演藝術等領域都有一些各自來標示及度量時間的方法^[5]^[6]^[7]。一些簡單，爭議較小的定義包括「時間是時鐘量測的物理量。」^[8]^[9]及「時間使得所有事情不會同時發生。」^[10]^[11]^[12]^[13]時間在國際單位製中的基本單位是秒，1967年起採用的定義為「銫-133原子在基態下的兩個超精細能級之間躍遷所對應的輻射的9192631770個周期的時間。」

哲學家對於時間有兩派不同的觀點：一派認為時間是宇宙的基本結構，是一個會依序列方式出現的維度，像艾薩克·牛頓就對時間有這樣的觀點。包括戈特弗里德·萊布尼茨及伊曼努爾·康德在內的另一派認為時間不是任何一種已經存在的維度，也不是任何會「流動」的實存物，時間只是一種心智的概念，配合空間和數可以讓人類對事件進行排序和比較。換句話說，時間不過是人為便於思考宇宙，而對物質運動劃分，是一種人定規則。

丈量與記錄

計時儀器

鐘錶是一種計時儀器。

中國古代的計時儀器有太陽鐘和機械鐘兩類。太陽鐘是以太陽的投影和方位來計時，分別以土圭、圭表、日晷為代表。由於地球軌道偏心率以及地球傾角的影響，真太陽時和平太陽時是不一致的，機械鐘應運而生，代表有水鐘、太陽儀、香篆鐘。

單位

時間的基本國際單位是秒。它現在以銫133原子基態的兩個超精細能級間躍遷對應的輻射的9,192,631,770個周期的持續時間為標準^[14]。

物理學

位於塔干洛的水平日晷

目前最廣泛被接受關於時間的物理理論是阿爾伯特·愛因斯坦的相對論。在相對論中，時間與空間一起組成四維時空，構成宇宙的基本結構。時間與空間都不是絕對的，觀察者在不同的相對速度或不同時空結構的測量點，所測量到時間的流易是不同的。狹義相對論預測一個具有相對運動的時鐘之時間流易比另一個靜止的時鐘之時間流易慢。在1971年，物理學家哈菲爾（Joe Hafele）與基廷（Richard Keating）做了證明。他們將高度精確的原子鐘放在飛機上繞著世界飛行，然後將讀到的時間與留在地面上完全一樣的時鐘做比較。結果證實：在飛機上的時間流易得比實驗室里的慢。據愛因斯坦的理論，當移動的速度越快，時間流易速度越慢，當移動速度達到光速的一半時，時間約慢13%。

另外，廣義相對論預測質量產生的重力場將造成扭曲的時空結構，並且在大質量（例如黑洞）附近的時鐘之時間流易比在距離大質量較遠的地方的時鐘之時間流易要慢。現有的儀器已經證實了這些相對論關於時間所做精確的預測，並且其成果已經應用於全球定位系統。

就今天的物理理論來說時間是連續的，不間斷的，也沒有量子特性。但有一些理論試圖將相對論與量子力學結合起來，如量子重力，弦理論，M理論，預言時間是間斷的，有量子特性的；但它們還沒有被實驗證明過的。另有一些理論猜測普朗克時間可能才是時間的最小單位。

根據史提芬·霍金所解出廣義相對論中的愛因斯坦方程式，顯示宇宙的時間是有一個起始點，由大霹靂（或稱大爆炸）開始的，在此之前的時間是毫無意義的。而物質與時空必須一起並存，沒有物質存在，時間也無意義。

人出生、成長、衰老、死亡，沒有反過來的。玻璃瓶掉到地上摔破，沒有破瓶子從地上跳起來合整的。古典力學無法解釋時間的不可逆性。兩個粒子彈性碰撞的過程順過來反過去沒有實質上的區別。時間的不可逆性只有在統計力學和熱力學的觀點下才可被理論地解釋。熱力學第二定律說在一個封閉的系統中（我們可以將宇宙看成是最大的可能的封閉系統）熵只能增大，不能減小。宇宙中的熵增大後不能減小，因此時間是不可逆的。

天文學

最早研究時間的科學不是物理學，而是天文學。天文學最重要的任務之一就是測量時間，從確定日的長短，四季的變化，到制定曆法。在古代中國和在西方一樣，制定曆法的需要是推動天文學理論發展的重要因素之一。

今天的天文學已與曆法或時間測量毫無關聯了，但天文學觀測對時間概念的發展依然非常重要。天體發出的光到地球上被觀測到需要一定的時間。離地球越遠的天體發出的光需要的時間也越長，因此對宇宙越遠的地方的觀測也是對宇宙越古老的時間的觀測。現在最被公認的宇宙學理論（宇宙大爆炸理論）認為時間與空間和宇宙內的質能一樣是在140億年前產生的。目前的天文學觀測估計宇宙的擴展是沒有盡頭的，因此時間也應該是沒有盡頭的。

哲學

傳統哲學對時間研究：古代的本體論採取獨斷的口吻宣布時間的本質和屬性，近代的認識論採取主客對立、非此即彼的態度判斷時間的本質和屬性，近現代的現象學和存在論者則從抽象的人出發去探索時間的本質問題。^{[來源請求]}

現在哲學家對於時間有兩派不同的觀點：一派認為時間是宇宙的基本結構，是一個會依序列方式出現的維度，艾薩克·牛頓就對時間有這様的觀點，因此也稱為「牛頓式的時間」^[15]。另一派認為時間不是任何一種已經存在的維度，也不是任何會「流動」的實存物，時間只是一種心智的概念，配合空間和數可以讓人類對事件排先後順序及進行比較^[16]。依照戈特弗里德·萊布尼茨及伊曼努爾·康德的傳統^[17]^[18]，第二派的觀點認為空間和時間「本身並不存在，而是我們表達事物方式的產物」，

文學

在文學中，時間的流易和不可逆性是一個古今中外一再提到的內容。光陰似箭，日月如梭，這句諺語既體現了古人對時間的最直接的領會：日與夜、光與陰的交匯，也體現了古人對時間不可逆性的認識以及對此的感慨。

在科幻小說中，時間旅行是常見題材之一。

參見

一些科學和藝術上的相關概念

一些和時間有關的單位

參考文獻

^ Oxford Dictionaries:Time. Oxford University Press. 2011 [18 December 2011]. （原始內容存檔於2012-07-04）. the indefinite continued of existence and events in the past, present, and future regarded as a whole
^ Webster's New World College Dictionary. 2010 [9 April 2011]. （原始內容存檔於2011-08-05）. 1.indefinite, unlimited duration in which things are considered as happening in the past, present, or future; every moment there has ever been or ever will be… a system of measuring duration 2.the period between two events or during which something exists, happens, or acts; measured or measurable interval
^ "Newton did for time what the Greek geometers did for space, idealized it into an exactly measurable dimension." About Time: Einstein's Unfinished Revolution, Paul Davies, p. 31, Simon & Schuster, 1996, ISBN 978-0-684-81822-1
^ Sean M Carroll. From Eternity to Here: The Quest for the Ultimate Theory of Time. Dutton. 2009. ISBN 978-0-525-95133-9.
^ Official Baseball Rules, 2011 Edition. Rules 8.03 and 8.04 (Free PDF download). Major League Baseball. 2011 [7 July 2012]. （原始內容存檔 (PDF)於2017-07-01）. Rule 8.03 Such preparatory pitches shall not consume more than one minute of time...Rule 8.04 When the bases are unoccupied, the pitcher shall deliver the ball to the batter within 12 seconds...The 12-second timing starts when the pitcher is in possession of the ball and the batter is in the box, alert to the pitcher. The timing stops when the pitcher releases the ball
^ Guinness Book of Baseball World Records. Guinness World Records, Ltd. [7 July 2012]. （原始內容存檔於2012-06-06）. The record for the fastest time for circling the bases is 13.3 seconds, set by Evar Swanson at Columbus, Ohio in 1932...The greatest reliably recorded speed at which a baseball has been pitched is 100.9 mph by Lynn Nolan Ryan (California Angels) at Anaheim Stadium in California on 20 August 1974.
^ Zeigler, Kenneth. Getting organized at work : 24 lessons to set goals, establish priorities, and manage your time. McGraw-Hill. 2008. ISBN 9780071591386. 108 pages
^ 引用錯誤：沒有為名為DefRefs01的參考文獻提供內容
^ 引用錯誤：沒有為名為Burnham的參考文獻提供內容
^ Cummings, Raymond King. The Girl in the Golden Atom. U of Nebraska Press. 1922: 46 [9 April 2011]. ISBN 978-0-8032-6457-1. Chapter 5. Cummings repeated this sentence in several of his novellas. Sources, such as this one （頁面存檔備份，存於網際網路檔案館）, attribute it to his earlier work, The Time Professor, in 1921. Before taking book form, several of Cummings's stories appeared serialized in magazines. The first eight chapters of his The Girl in the Golden Atom appeared （頁面存檔備份，存於網際網路檔案館） in All-Story Magazine on 15 March 1919. In the novel version （頁面存檔備份，存於網際網路檔案館） the quote about time appears in Chapter V （頁面存檔備份，存於網際網路檔案館）.
^ International, Rotary. The Rotarian. Published by Rotary International: 47. Aug 1973 [9 April 2011]. ISSN 0035-838X. , What does a man possess? page 47 （頁面存檔備份，存於網際網路檔案館）
^ Daintith, John. Biographical Encyclopedia of Scientists third. CRC Press. 2008: 796 [9 April 2011]. ISBN 1-4200-7271-4. , Page 796, quoting Wheeler from the American Journal of Physics, 1978 （頁面存檔備份，存於網際網路檔案館）
^ Davies, Davies. About time: Einstein's unfinished revolution. Simon & Schuster. 1995: 236 [9 April 2011]. ISBN 0-671-79964-9.
^ Leap Seconds. Time Service Department, United States Naval Observatory. [2006-12-31]. （原始內容存檔於2012-05-27）.
^ Markosian, Ned. Time. Edward N. Zalta (編). The Stanford Encyclopedia of Philosophy (Winter 2002 Edition). [23 September 2011]. （原始內容存檔於2006-09-14）. The opposing view, normally referred to either as 「Platonism with Respect to Time」 or as 「Absolutism with Respect to Time,」 has been defended by Plato, Newton, and others. On this view, time is like an empty container into which events may be placed; but it is a container that exists independently of whether or not anything is placed in it.
^ Navratil, Gerhard. Research Trends in Geographic Information Science. Springer Japan. 2009: 217 [9 April 2011]. ISBN 3-540-88243-X. （原始內容存檔於2014-11-29）.
^ Mattey, G. J. : UC Davis. Critique of Pure Reason, Lecture notes: Philosophy 175 UC Davis. 22 January 1997 [9 April 2011]. （原始內容存檔於2005年3月14日）. What is correct in the Leibnizian view was its anti-metaphysical stance. Space and time do not exist in and of themselves, but in some sense are the product of the way we represent things. The[y] are ideal, though not in the sense in which Leibniz thought they are ideal (figments of the imagination). The ideality of space is its mind-dependence: it is only a condition of sensibility.... Kant concluded "absolute space is not an object of outer sensation; it is rather a fundamental concept which first of all makes possible all such outer sensation."...Much of the argumentation pertaining to space is applicable, mutatis mutandis, to time, so I will not rehearse the arguments. As space is the form of outer intuition, so time is the form of inner intuition.... Kant claimed that time is real, it is "the real form of inner intuition."
^ McCormick, Matt : California State University, Sacramento. Immanuel Kant (1724–1804) Metaphysics: 4. Kant's Transcendental Idealism. The Internet Encyclopedia of Philosophy. 2006 [9 April 2011]. （原始內容存檔於2012-10-31）. Time, Kant argues, is also necessary as a form or condition of our intuitions of objects. The idea of time itself cannot be gathered from experience because succession and simultaneity of objects, the phenomena that would indicate the passage of time, would be impossible to represent if we did not already possess the capacity to represent objects in time.... Another way to put the point is to say that the fact that the mind of the knower makes the a priori contribution does not mean that space and time or the categories are mere figments of the imagination. Kant is an empirical realist about the world we experience; we can know objects as they appear to us. He gives a robust defense of science and the study of the natural world from his argument about the mind's role in making nature. All discursive, rational beings must conceive of the physical world as spatially and temporally unified, he argues.

外部連結

倪梁康：〈縱意向性：時間．發生．歷史〉（頁面存檔備份，存於網際網路檔案館）（2010）
黃俊傑：〈傳統中國歷史思想中的「時間」與「超時間」概念（頁面存檔備份，存於網際網路檔案館）〉
時間科普網站（中國）
時間與頻率國家標準實驗室（台灣全國性時頻追溯體系）（頁面存檔備份，存於網際網路檔案館）
國家地理頻道專題影片《超乎想像的宇宙-時間扭曲（頁面存檔備份，存於網際網路檔案館）》

[1] Oxford Dictionaries:Time. Oxford University Press. 2011 [18 December 2011]. （原始內容存檔於2012-07-04）. the indefinite continued of existence and events in the past, present, and future regarded as a whole

[DefRefs02-2] Webster's New World College Dictionary. 2010 [9 April 2011]. （原始內容存檔於2011-08-05）. 1.indefinite, unlimited duration in which things are considered as happening in the past, present, or future; every moment there has ever been or ever will be… a system of measuring duration 2.the period between two events or during which something exists, happens, or acts; measured or measurable interval

[3] "Newton did for time what the Greek geometers did for space, idealized it into an exactly measurable dimension." About Time: Einstein's Unfinished Revolution, Paul Davies, p. 31, Simon & Schuster, 1996, ISBN 978-0-684-81822-1

[Carroll2009-4] Sean M Carroll. From Eternity to Here: The Quest for the Ultimate Theory of Time. Dutton. 2009. ISBN 978-0-525-95133-9.

[MLB-5] Official Baseball Rules, 2011 Edition. Rules 8.03 and 8.04 (Free PDF download). Major League Baseball. 2011 [7 July 2012]. （原始內容存檔 (PDF)於2017-07-01）. Rule 8.03 Such preparatory pitches shall not consume more than one minute of time...Rule 8.04 When the bases are unoccupied, the pitcher shall deliver the ball to the batter within 12 seconds...The 12-second timing starts when the pitcher is in possession of the ball and the batter is in the box, alert to the pitcher. The timing stops when the pitcher releases the ball

[guiness-6] Guinness Book of Baseball World Records. Guinness World Records, Ltd. [7 July 2012]. （原始內容存檔於2012-06-06）. The record for the fastest time for circling the bases is 13.3 seconds, set by Evar Swanson at Columbus, Ohio in 1932...The greatest reliably recorded speed at which a baseball has been pitched is 100.9 mph by Lynn Nolan Ryan (California Angels) at Anaheim Stadium in California on 20 August 1974.

[Zeigler-7] Zeigler, Kenneth. Getting organized at work : 24 lessons to set goals, establish priorities, and manage your time. McGraw-Hill. 2008. ISBN 9780071591386. 108 pages

[DefRefs01-8] 引用錯誤：沒有為名為DefRefs01的參考文獻提供內容

[Burnham-9] 引用錯誤：沒有為名為Burnham的參考文獻提供內容

[10] Cummings, Raymond King. The Girl in the Golden Atom. U of Nebraska Press. 1922: 46 [9 April 2011]. ISBN 978-0-8032-6457-1. Chapter 5. Cummings repeated this sentence in several of his novellas. Sources, such as this one （頁面存檔備份，存於網際網路檔案館）, attribute it to his earlier work, The Time Professor, in 1921. Before taking book form, several of Cummings's stories appeared serialized in magazines. The first eight chapters of his The Girl in the Golden Atom appeared （頁面存檔備份，存於網際網路檔案館） in All-Story Magazine on 15 March 1919. In the novel version （頁面存檔備份，存於網際網路檔案館） the quote about time appears in Chapter V （頁面存檔備份，存於網際網路檔案館）.

[11] International, Rotary. The Rotarian. Published by Rotary International: 47. Aug 1973 [9 April 2011]. ISSN 0035-838X. , What does a man possess? page 47 （頁面存檔備份，存於網際網路檔案館）

[12] Daintith, John. Biographical Encyclopedia of Scientists third. CRC Press. 2008: 796 [9 April 2011]. ISBN 1-4200-7271-4. , Page 796, quoting Wheeler from the American Journal of Physics, 1978 （頁面存檔備份，存於網際網路檔案館）

[13] Davies, Davies. About time: Einstein's unfinished revolution. Simon & Schuster. 1995: 236 [9 April 2011]. ISBN 0-671-79964-9.

[USNO-14] Leap Seconds. Time Service Department, United States Naval Observatory. [2006-12-31]. （原始內容存檔於2012-05-27）.

[Markosian-15] Markosian, Ned. Time. Edward N. Zalta (編). The Stanford Encyclopedia of Philosophy (Winter 2002 Edition). [23 September 2011]. （原始內容存檔於2006-09-14）. The opposing view, normally referred to either as 「Platonism with Respect to Time」 or as 「Absolutism with Respect to Time,」 has been defended by Plato, Newton, and others. On this view, time is like an empty container into which events may be placed; but it is a container that exists independently of whether or not anything is placed in it.

[16] Navratil, Gerhard. Research Trends in Geographic Information Science. Springer Japan. 2009: 217 [9 April 2011]. ISBN 3-540-88243-X. （原始內容存檔於2014-11-29）.

[Mattey-17] Mattey, G. J. : UC Davis. Critique of Pure Reason, Lecture notes: Philosophy 175 UC Davis. 22 January 1997 [9 April 2011]. （原始內容存檔於2005年3月14日）. What is correct in the Leibnizian view was its anti-metaphysical stance. Space and time do not exist in and of themselves, but in some sense are the product of the way we represent things. The[y] are ideal, though not in the sense in which Leibniz thought they are ideal (figments of the imagination). The ideality of space is its mind-dependence: it is only a condition of sensibility.... Kant concluded "absolute space is not an object of outer sensation; it is rather a fundamental concept which first of all makes possible all such outer sensation."...Much of the argumentation pertaining to space is applicable, mutatis mutandis, to time, so I will not rehearse the arguments. As space is the form of outer intuition, so time is the form of inner intuition.... Kant claimed that time is real, it is "the real form of inner intuition."

[McCormick-18] McCormick, Matt : California State University, Sacramento. Immanuel Kant (1724–1804) Metaphysics: 4. Kant's Transcendental Idealism. The Internet Encyclopedia of Philosophy. 2006 [9 April 2011]. （原始內容存檔於2012-10-31）. Time, Kant argues, is also necessary as a form or condition of our intuitions of objects. The idea of time itself cannot be gathered from experience because succession and simultaneity of objects, the phenomena that would indicate the passage of time, would be impossible to represent if we did not already possess the capacity to represent objects in time.... Another way to put the point is to say that the fact that the mind of the knower makes the a priori contribution does not mean that space and time or the categories are mere figments of the imagination. Kant is an empirical realist about the world we experience; we can know objects as they appear to us. He gives a robust defense of science and the study of the natural world from his argument about the mind's role in making nature. All discursive, rational beings must conceive of the physical world as spatially and temporally unified, he argues.

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