{"id":78097,"date":"2026-05-04T10:42:50","date_gmt":"2026-05-04T08:42:50","guid":{"rendered":"https:\/\/www.iemn.fr\/?p=78097"},"modified":"2026-05-18T09:47:22","modified_gmt":"2026-05-18T07:47:22","slug":"gravitational-waltz-on-a-soap-film","status":"publish","type":"post","link":"https:\/\/www.iemn.fr\/en\/newsletter\/gravitational-waltz-on-a-soap-film.html","title":{"rendered":"Gravitational waltz on a soap film"},"content":{"rendered":"<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-sx3vs0-44b2a8ab14b4051c54bfc3098d7228b7\">\n.flex_column.av-sx3vs0-44b2a8ab14b4051c54bfc3098d7228b7{\nborder-radius:0px 0px 0px 0px;\npadding:0px 0px 0px 0px;\n}\n<\/style>\n<div  class='flex_column av-sx3vs0-44b2a8ab14b4051c54bfc3098d7228b7 av_one_full  avia-builder-el-0  el_before_av_one_half  avia-builder-el-first  first flex_column_div av-zero-column-padding'     ><section  class='av_textblock_section av-lq2h9d9t-cc8fde46f6e45211a1b6d6c476b8c108'   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" ><div id=\"attachment_78071\" style=\"width: 1210px\" class=\"wp-caption alignright\"><a href=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/05\/Image2.png\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-78071\" class=\"wp-image-78071 size-full\" src=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/05\/Image2.png\" alt=\"\" width=\"1200\" height=\"230\" srcset=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/05\/Image2.png 1200w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/05\/Image2-300x58.png 300w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/05\/Image2-1030x197.png 1030w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/05\/Image2-768x147.png 768w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/05\/Image2-18x3.png 18w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/05\/Image2-705x135.png 705w\" sizes=\"auto, (max-width: 1200px) 100vw, 1200px\" \/><\/a><p id=\"caption-attachment-78071\" class=\"wp-caption-text\">Bottom view of a horizontal soap film deformed by a droplet deposited at the center of the film.<\/p><\/div>\n<\/div><\/section><br \/>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-moqw71wu-412c7932345a7f4c53bf67a0cf8e33cb\">\n#top .hr.hr-invisible.av-moqw71wu-412c7932345a7f4c53bf67a0cf8e33cb{\nheight:50px;\n}\n<\/style>\n<div  class='hr av-moqw71wu-412c7932345a7f4c53bf67a0cf8e33cb hr-invisible  avia-builder-el-2  el_after_av_textblock  el_before_av_hr'><span class='hr-inner'><span class=\"hr-inner-style\"><\/span><\/span><\/div><br \/>\n<div  class='hr av-j7znhx-e3ee2d6f36b10bddf7d0ddaff94411ca hr-default  avia-builder-el-3  el_after_av_hr  el_before_av_textblock'><span class='hr-inner'><span class=\"hr-inner-style\"><\/span><\/span><\/div><br \/>\n<section  class='av_textblock_section av-lq2gsmqj-6f79b7b0b0e14a78be1a6c67ea7c7132'   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" ><h1 style=\"text-align: center;\"><strong><span style=\"color: #99ccff;\">Gravitational waltz on a soap film<\/span><\/strong><\/h1>\n<\/div><\/section><\/p><\/div>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-15dykqo-d9aa9d5723e5b35a36b3d8a512458f8f\">\n@keyframes av_boxShadowEffect_av-15dykqo-d9aa9d5723e5b35a36b3d8a512458f8f-column {\n0%   { box-shadow:  0 0 0 0 #d1d1d1; opacity: 1; }\n100% { box-shadow:  0 0 10px 0 #d1d1d1; opacity: 1; }\n}\n.flex_column.av-15dykqo-d9aa9d5723e5b35a36b3d8a512458f8f{\nbox-shadow: 0 0 10px 0 #d1d1d1;\nborder-width:4px;\nborder-style:solid;\nborder-radius:10px 10px 10px 10px;\npadding:20px 20px 20px 20px;\nbackground-color:#ededed;\n}\n<\/style>\n<div  class='flex_column av-15dykqo-d9aa9d5723e5b35a36b3d8a512458f8f av_one_half  avia-builder-el-5  el_after_av_one_full  el_before_av_two_fifth  first flex_column_div shadow-not-animated  column-top-margin'     ><section  class='av_textblock_section av-lq2hhk08-de2267eda297e5e01beeb815d5568d08'   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" ><h5><\/h5>\n<h4><\/h4>\n<div id=\"attachment_78073\" style=\"width: 253px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/05\/Image1.png\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-78073\" class=\"wp-image-78073\" src=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/05\/Image1.png\" alt=\"\" width=\"243\" height=\"236\" srcset=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/05\/Image1.png 800w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/05\/Image1-300x292.png 300w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/05\/Image1-768x748.png 768w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/05\/Image1-12x12.png 12w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/05\/Image1-36x36.png 36w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/05\/Image1-705x686.png 705w\" sizes=\"auto, (max-width: 243px) 100vw, 243px\" \/><\/a><p id=\"caption-attachment-78073\" class=\"wp-caption-text\">Two liquid lenses orbiting on a soap film. The lenses distort the image of the background located beneath the film.<\/p><\/div>\n<h5>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-qawvnx-7a74d8bc7bca7214f06a484a64543370\">\n.av_font_icon.av-qawvnx-7a74d8bc7bca7214f06a484a64543370{\ncolor:#99ccff;\nborder-color:#99ccff;\n}\n.av_font_icon.av-qawvnx-7a74d8bc7bca7214f06a484a64543370 .av-icon-char{\nfont-size:20px;\nline-height:20px;\n}\n<\/style>\n<span  class='av_font_icon av-qawvnx-7a74d8bc7bca7214f06a484a64543370 avia_animate_when_visible av-icon-style- avia-icon-pos-left avia-icon-animate'><span class='av-icon-char' aria-hidden='true' data-av_icon='\ue881' data-av_iconfont='entypo-fontello' ><\/span><\/span><\/h5>\n<p>Gravitational interactions shape the structures of the Universe, from planetary orbits to interactions between galaxies. They give rise to characteristic dynamics such as complex orbits, tidal spiral arms, and bridges, which are commonly observed at astrophysical scales but rarely observed at human scales. Recently, teams from IEMN and the Institut Pprime observed the emergence of such structures when two miscible droplets, placed on a soap film, orbit, collide, and merge.<\/p>\n<p>Experimentally, a horizontal soap film, composed of a mixture of water, glycerol, and surfactant, is formed on a horizontal support. One or several droplets are then deposited onto this soap film, forming stable structures called \u201clenses,\u201d whose shape results from a balance between capillary and gravitational forces. When multiple droplets are introduced onto the film with an initial horizontal velocity (using a dropslide), they begin to orbit each other and eventually collide and merge, in a choreography reminiscent of galaxy mergers.<\/p>\n<p>The observation of such dynamics is made possible by (i) the formation of stable lenses when droplets are deposited on the soap film, (ii) long-range interactions between these lenses, analogous to two-dimensional gravitational attraction forces, and (iii) the deformable nature of these lenses when they interact. The IEMN team modeled the interactions between orbiting lenses and demonstrated that they originate from the deformation of the film, resulting from a balance between capillary and gravitational forces. They were able to quantify this force and reproduce complex orbits of two lenses with an initial velocity. The next step will be to study and model the collision and merging of the lenses.<\/p>\n<p>This work opens up new perspectives for gravitational analogues, enabling the investigation, at human scales, of simplified representations of phenomena that typically occur at scales beyond the reach of human observation.<\/p>\n<hr \/>\n<h5>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-qawvnx-1-f30b193258b55e359feb7fd33411f334\">\n.av_font_icon.av-qawvnx-1-f30b193258b55e359feb7fd33411f334{\ncolor:#99ccff;\nborder-color:#99ccff;\n}\n.av_font_icon.av-qawvnx-1-f30b193258b55e359feb7fd33411f334 .av-icon-char{\nfont-size:20px;\nline-height:20px;\n}\n<\/style>\n<span  class='av_font_icon av-qawvnx-1-f30b193258b55e359feb7fd33411f334 avia_animate_when_visible av-icon-style- avia-icon-pos-left avia-icon-animate'><span class='av-icon-char' aria-hidden='true' data-av_icon='\ue881' data-av_iconfont='entypo-fontello' ><\/span><\/span><\/h5>\n<p>This work, published in PNAS Nexus <span style=\"color: #333399;\">(<a style=\"color: #333399;\" href=\"https:\/\/doi.org\/10.1093\/pnasnexus\/pgag079\" target=\"_blank\" rel=\"noopener\">https:\/\/doi.org\/10.1093\/pnasnexus\/pgag079<\/a>)<\/span> was highlighted in an article by the newspaper Le Monde :<\/p>\n<p><a href=\"https:\/\/www.lemonde.fr\/sciences\/article\/2026\/04\/16\/quand-des-gouttes-sur-un-film-de-savon-permettent-de-comprendre-la-formation-des-galaxies_6680461_1650684.html\" target=\"_blank\" rel=\"noopener\"><span style=\"color: #333399;\">Newspaper le Monde<\/span><\/a><\/p>\n<p style=\"text-align: left;\"><strong><span style=\"color: #f16728;\">\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-mqde7m-11665d57be50482f466d54b8a3268ec6\">\n.av_font_icon.av-mqde7m-11665d57be50482f466d54b8a3268ec6{\ncolor:#f16728;\nborder-color:#f16728;\n}\n.av_font_icon.av-mqde7m-11665d57be50482f466d54b8a3268ec6 .av-icon-char{\nfont-size:25px;\nline-height:25px;\n}\n<\/style>\n<span  class='av_font_icon av-mqde7m-11665d57be50482f466d54b8a3268ec6 avia_animate_when_visible av-icon-style- avia-icon-pos-left avia-icon-animate'><span class='av-icon-char' aria-hidden='true' data-av_icon='\ue805' data-av_iconfont='entypo-fontello' ><\/span><\/span><\/span>mickael.baudoin<img loading=\"lazy\" decoding=\"async\" class=\"align=absbottom wp-image-73335 size-full\" src=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2025\/05\/arobase6.png\" alt=\"\" width=\"16\" height=\"14\" srcset=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2025\/05\/arobase6.png 16w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2025\/05\/arobase6-14x12.png 14w\" sizes=\"auto, (max-width: 16px) 100vw, 16px\" \/>iemn.fr\u00a0<\/strong><\/p>\n<\/div><\/section><\/div>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-2cesnp-c72d05c24232caf1606302d0bb47819d\">\n@keyframes av_boxShadowEffect_av-2cesnp-c72d05c24232caf1606302d0bb47819d-column {\n0%   { box-shadow:  0 0 0 0 #e5e5e5; opacity: 1; }\n100% { box-shadow:  0 0 10px 0 #e5e5e5; opacity: 1; }\n}\n.flex_column.av-2cesnp-c72d05c24232caf1606302d0bb47819d{\nbox-shadow: 0 0 10px 0 #e5e5e5;\nborder-radius:10px 10px 10px 10px;\npadding:15px 15px 15px 15px;\nbackground-color:rgba(190,209,232,0.43);\n}\n.flex_column.av-2cesnp-c72d05c24232caf1606302d0bb47819d .avia-divider-svg-top{\nborder-radius:10px 10px 0 0;\n}\n.flex_column.av-2cesnp-c72d05c24232caf1606302d0bb47819d .avia-divider-svg-top svg{\nheight:50px;\nwidth:calc(100% + 1.3px);\nfill:#bcbcbc;\n}\n<\/style>\n<div  class='flex_column av-2cesnp-c72d05c24232caf1606302d0bb47819d av_two_fifth  avia-builder-el-10  el_after_av_one_half  el_before_av_hr  flex_column_div shadow-not-animated  column-top-margin'     ><div class='avia-divider-svg avia-divider-svg-triangle-asymmetrical avia-divider-svg-top avia-svg-original'><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" viewbox=\"0 0 1000 100\" preserveaspectratio=\"none\">\n\t<path d=\"M738,99l262-93V0H0v5.6L738,99z\"\/>\n<\/svg><\/div><p>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-moqwfgjw-e1e72b6a196e06b76a3b45bd709e14b9\">\n#top .hr.hr-invisible.av-moqwfgjw-e1e72b6a196e06b76a3b45bd709e14b9{\nheight:50px;\n}\n<\/style>\n<div  class='hr av-moqwfgjw-e1e72b6a196e06b76a3b45bd709e14b9 hr-invisible  avia-builder-el-11  el_before_av_textblock  avia-builder-el-first'><span class='hr-inner'><span class=\"hr-inner-style\"><\/span><\/span><\/div><br \/>\n<section  class='av_textblock_section av-moqw0594-193a3b2360a3a1af632697c7868a8687'   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" ><div id=\"attachment_78075\" style=\"width: 376px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/05\/Image3.png\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-78075\" class=\"wp-image-78075 size-full\" src=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/05\/Image3.png\" alt=\"\" width=\"366\" height=\"359\" srcset=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/05\/Image3.png 366w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/05\/Image3-300x294.png 300w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/05\/Image3-12x12.png 12w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/05\/Image3-36x36.png 36w\" sizes=\"auto, (max-width: 366px) 100vw, 366px\" \/><\/a><p id=\"caption-attachment-78075\" class=\"wp-caption-text\">Dynamics of two droplets orbiting on a soap film. The points correspond to the positions of the centers of mass of the two lenses as a function of time, while the line segments connect the centers of mass of the two lenses at each instant.<\/p><\/div>\n<hr \/>\n<\/div><\/section><\/p><\/div>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-lq3rrbn6-b2fad551015528b25fb537190ccf1056\">\n#top .hr.hr-invisible.av-lq3rrbn6-b2fad551015528b25fb537190ccf1056{\nheight:20px;\n}\n<\/style>\n<div  class='hr av-lq3rrbn6-b2fad551015528b25fb537190ccf1056 hr-invisible  avia-builder-el-13  el_after_av_two_fifth  el_before_av_four_fifth'><span class='hr-inner'><span class=\"hr-inner-style\"><\/span><\/span><\/div><\/p>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-moqxvoph-864c8f470c57613ef07da986f7f062f9\">\n.flex_column.av-moqxvoph-864c8f470c57613ef07da986f7f062f9{\nborder-width:1px;\nborder-color:#e5e5e5;\nborder-style:solid;\nborder-radius:20px 20px 20px 20px;\npadding:15px 15px 15px 15px;\nbackground-color:rgba(123,176,231,0.47);\n}\n<\/style>\n<div  class='flex_column av-moqxvoph-864c8f470c57613ef07da986f7f062f9 av_four_fifth  avia-builder-el-14  el_after_av_hr  avia-builder-el-last  first flex_column_div'     ><section  class='av_textblock_section av-lq3ru9ya-29405bed54ddc2f1034afe84a9bb7978'   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" ><p>R\u00e9f\u00e9rence\u00a0:<\/p>\n<p>[1] J.P. Martischang, B. Reichert, I. Haouche, G. Rousseaux, A. Duchesne &amp; M. Baudoin, PNAS Nexus, 5, pgag079 (2026)<\/p>\n<\/div><\/section><\/div>","protected":false},"excerpt":{"rendered":"","protected":false},"author":20,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[297],"tags":[],"class_list":["post-78097","post","type-post","status-publish","format-standard","hentry","category-newsletter"],"_links":{"self":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/78097","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/users\/20"}],"replies":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/comments?post=78097"}],"version-history":[{"count":5,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/78097\/revisions"}],"predecessor-version":[{"id":78281,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/78097\/revisions\/78281"}],"wp:attachment":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/media?parent=78097"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/categories?post=78097"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/tags?post=78097"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}