<!DOCTYPE html>
<html class="client-nojs vector-feature-night-mode-disabled vector-feature-language-in-header-enabled vector-feature-language-in-main-page-header-disabled vector-feature-page-tools-pinned-disabled vector-feature-toc-pinned-clientpref-1 vector-feature-main-menu-pinned-disabled vector-feature-limited-width-clientpref-1 vector-feature-limited-width-content-enabled vector-feature-custom-font-size-clientpref-1 vector-feature-appearance-pinned-clientpref-1 vector-sticky-header-enabled" lang="en" dir="ltr"><head>
<meta charset="UTF-8">
<title>Local reference frame</title>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link rel="canonical" href="https://en.wikipedia.org/wiki/Local_reference_frame"> <link href="./mw/ext.cite.styles.css" rel="stylesheet" type="text/css">
<link href="./mw/skins.vector.icons.css" rel="stylesheet" type="text/css">
<link href="./mw/skins.vector.search.codex.styles.css" rel="stylesheet" type="text/css">
<link href="./mw/skins.vector.styles.css" rel="stylesheet" type="text/css">
<link href="./mw/user.styles.css" rel="stylesheet" type="text/css">
<meta name="ResourceLoaderDynamicStyles" content="">
<link rel="stylesheet" type="text/css" href="./mw/site.styles.css">
<link rel="stylesheet" type="text/css" href="./mw/noscript.css">
<link rel="stylesheet" type="text/css" href="./footer.css">
<link rel="stylesheet" type="text/css" href="./vector-2022.css">
</head>
<body class="skin--responsive skin-vector skin-vector-search-vue mediawiki ltr sitedir-ltr mw-hide-empty-elt ns-0 ns-subject page-Local_reference_frame rootpage-Local_reference_frame skin-vector-2022 action-view">
<div class="mw-page-container">
<div class="mw-page-container-inner">
<div class="mw-content-container">
<main id="content" class="mw-body">
<header class="mw-body-header vector-page-titlebar">
<h1 id="firstHeading" class="firstHeading mw-first-heading">
<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Local reference frame</span></span>
</h1>
</header>
<a id="top"></a>
<div id="bodyContent" class="vector-body ve-init-mw-desktopArticleTarget-targetContainer" aria-labelledby="firstHeading" data-mw-ve-target-container="">
<div id="mw-content-text" class="mw-body-content mw-content-ltr" lang="en" dir="ltr"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr">
<style data-mw-deduplicate="TemplateStyles:r1251242444">
/* start https://en.wikipedia.org/ */
.mw-parser-output .ambox{border:1px solid #a2a9b1;border-left:10px solid #36c;background-color:#fbfbfb;box-sizing:border-box}.mw-parser-output .ambox+link+.ambox,.mw-parser-output .ambox+link+style+.ambox,.mw-parser-output .ambox+link+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+style+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+link+.ambox{margin-top:-1px}html body.mediawiki .mw-parser-output .ambox.mbox-small-left{margin:4px 1em 4px 0;overflow:hidden;width:238px;border-collapse:collapse;font-size:88%;line-height:1.25em}.mw-parser-output .ambox-speedy{border-left:10px solid #b32424;background-color:#fee7e6}.mw-parser-output .ambox-delete{border-left:10px solid #b32424}.mw-parser-output .ambox-content{border-left:10px solid #f28500}.mw-parser-output .ambox-style{border-left:10px solid #fc3}.mw-parser-output .ambox-move{border-left:10px solid #9932cc}.mw-parser-output .ambox-protection{border-left:10px solid #a2a9b1}.mw-parser-output .ambox .mbox-text{border:none;padding:0.25em 0.5em;width:100%}.mw-parser-output .ambox .mbox-image{border:none;padding:2px 0 2px 0.5em;text-align:center}.mw-parser-output .ambox .mbox-imageright{border:none;padding:2px 0.5em 2px 0;text-align:center}.mw-parser-output .ambox .mbox-empty-cell{border:none;padding:0;width:1px}.mw-parser-output .ambox .mbox-image-div{width:52px}@media(min-width:720px){.mw-parser-output .ambox{margin:0 10%}}@media print{body.ns-0 .mw-parser-output .ambox{display:none!important}}
/* end https://en.wikipedia.org/ */
</style>
<p>In <a href="Theoretical_physics" title="Theoretical physics">theoretical physics</a>, a <b>local reference frame</b> (<b>local frame</b>) refers to a <a href="Coordinate_system" title="Coordinate system">coordinate system</a> or <a href="Frame_of_reference" title="Frame of reference">frame of reference</a> that is only expected to function over a small region or a restricted region of space or <a href="Spacetime" title="Spacetime">spacetime</a>.
</p><p>The term is most often used in the context of the application of <b>local inertial frames</b> to small regions of a <a href="Gravitational_field" title="Gravitational field">gravitational field</a>. Although gravitational <a href="Tidal_forces" class="mw-redirect" title="Tidal forces">tidal forces</a> will cause the background geometry to become noticeably <a href="Non-Euclidean" class="mw-redirect" title="Non-Euclidean">non-Euclidean</a> over larger regions, if we restrict ourselves to a sufficiently small region containing a cluster of objects falling together in an <i>effectively</i> uniform gravitational field, their physics can be described as the physics of that cluster in a space free from explicit background gravitational effects.
</p>
<meta property="mw:PageProp/toc">
<div class="mw-heading mw-heading2"><h2 id="Equivalence_principle">Equivalence principle</h2></div>
<style data-mw-deduplicate="TemplateStyles:r1236090951">
/* start https://en.wikipedia.org/ */
.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}
/* end https://en.wikipedia.org/ */
</style><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="Equivalence_principle" title="Equivalence principle">Equivalence principle</a></div>
<p>When constructing his <a href="General_theory_of_relativity" class="mw-redirect" title="General theory of relativity">general theory of relativity</a>, <a href="Albert_Einstein" title="Albert Einstein">Einstein</a> made the following observation: a freely falling object in a gravitational field will not be able to detect the existence of the field by making local measurements ("a falling man feels no gravity").<sup id="cite_ref-Zee_1-0" class="reference"><a href="#cite_note-Zee-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> Einstein was then able to complete his general theory by arguing that the physics of curved spacetime must reduce over small regions to the physics of simple inertial mechanics (in this case <a href="Special_relativity" title="Special relativity">special relativity</a>) for small free-falling regions.<sup id="cite_ref-Zee_1-1" class="reference"><a href="#cite_note-Zee-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> Einstein referred to this as "the happiest idea of my life" (Zee (2001), p. 17.<sup id="cite_ref-Zee_1-2" class="reference"><a href="#cite_note-Zee-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>
</p>
<div class="mw-heading mw-heading2"><h2 id="Laboratory_frame">Laboratory frame</h2></div>
<p>In physics, the <b>laboratory frame of reference</b>, or <b>lab frame</b> for short, is a <a href="Frame_of_reference" title="Frame of reference">frame of reference</a> centered on the <a href="Laboratory" title="Laboratory">laboratory</a> in which the <a href="Experiment" title="Experiment">experiment</a> (either real or thought experiment) is done. This is the reference frame in which the laboratory is at rest. Also, this is usually the frame of reference in which <a href="Measurement" title="Measurement">measurements</a> are made, since they are presumed (unless stated otherwise) to be made by laboratory instruments. An example of instruments in a lab frame, would be the <a href="Particle_detector" title="Particle detector">particle detectors</a> at the detection facility of a <a href="Particle_accelerator" title="Particle accelerator">particle accelerator</a>.
</p>
<div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2></div>
<ul><li><a href="Breit_frame" title="Breit frame">Breit frame</a></li>
<li><a href="Center-of-mass_frame" class="mw-redirect" title="Center-of-mass frame">Center-of-mass frame</a></li>
<li><a href="Frame_bundle" title="Frame bundle">Frame bundle</a></li>
<li><a href="Inertial_frame_of_reference" title="Inertial frame of reference">Inertial frame of reference</a></li>
<li><a href="Local_coordinates" title="Local coordinates">Local coordinates</a></li>
<li><a href="Local_spacetime_structure" class="mw-redirect" title="Local spacetime structure">Local spacetime structure</a></li>
<li><a href="Lorentz_covariance" title="Lorentz covariance">Lorentz covariance</a></li>
<li><a href="Minkowski_space" title="Minkowski space">Minkowski space</a></li>
<li><a href="Normal_coordinates" title="Normal coordinates">Normal coordinates</a></li></ul>
<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>
<style data-mw-deduplicate="TemplateStyles:r1239543626">
/* start https://en.wikipedia.org/ */
.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}
/* end https://en.wikipedia.org/ */
</style><div class="reflist">
<div class="mw-references-wrap"><ol class="references">
<li id="cite_note-Zee-1"><span class="mw-cite-backlink">^ <a href="#cite_ref-Zee_1-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Zee_1-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Zee_1-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">
/* start https://en.wikipedia.org/ */
.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("./mw/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("./mw/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("./mw/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("./mw/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}
/* end https://en.wikipedia.org/ */
</style><cite id="CITEREFZee2001" class="citation book cs1">Zee, A. (2001). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=B7OdsjBg5WcC&dq=a+falling+man+feels+no+gravity&pg=PA17"><i>Einstein's Universe: Gravity at Work and Play</i></a>. Oxford University Press. pp. <span class="nowrap">5–</span>7, <span class="nowrap">10–</span>17, <span class="nowrap">21–</span>27, <span class="nowrap">230–</span>242. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-0-19-514285-3</bdi><span class="reference-accessdate">. Retrieved <span class="nowrap">June 18,</span> 2025</span>.</cite></span>
</li>
<li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><cite id="CITEREFEinstein2004" class="citation book cs1">Einstein, Albert (2004). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=mbUGZYzs878C&dq=%22the+happiest+idea+of+my+life%22+Einstein&pg=PR13"><i>Relativity: The Special and General Theory</i></a>. Barnes & Noble Publishing. p. XIII. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-0-7607-5921-9</bdi><span class="reference-accessdate">. Retrieved <span class="nowrap">June 18,</span> 2025</span>.</cite></span>
</li>
</ol></div></div></div><!--htdig_noindex--><div><div class="zim-footer">
This article is issued from <a class="external text" title="Last edited on 2025-07-06" href="https://en.wikipedia.org/wiki/?title=Local_reference_frame&oldid=1299166280">Wikipedia</a>. The text is available under <a class="external text" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en">Creative Commons Attribution-Share Alike 4.0</a> unless otherwise noted. Additional terms may apply for the media files.
</div>
</div><!--/htdig_noindex--></div>
</div>
</main>
</div>
</div>
</div>
</body></html>