{{Short description|Physical phenomenon}} thumb|Snapshot of chain fountain process The '''chain fountain''' phenomenon, also known as '''self-siphoning beads''', '''Newton's beads''', or the '''Mould effect''', is a physical phenomenon observed with a chain placed inside a jar. One end of the chain is pulled from the jar and is allowed to fall under the influence of gravity. This process establishes a self-sustaining flow of the chain which rises over the edge and goes down to the floor or ground beneath it, as if being sucked out of the jar by an invisible siphon. For chains with small adjacent beads, the arc can ascend into the air over and above the edge of the jar with a noticeable gap; this gap is greater when the chain falls farther.<ref>{{cite magazine |title=Gravity-Defying, Self-Siphoning Metal Beads Explained [Video] |url=https://blogs.scientificamerican.com/observations/2013/07/03/gravity-defying-self-siphoning-metal-beads-explained-video/ |magazine=Scientific American |first=Philip |last=Yam |date=2013-07-03 }}</ref>
The '''self-siphoning effect''' is also observed in non-Newtonian fluids.
== History == The self-siphoning phenomenon has been known for some time, and had become a topic of public discussion many times in the past. Science entertainer Steve Spangler presented this phenomenon on TV in 2009, both with beads and viscoelastic liquids.<ref name=":2" /><ref>{{Citation|author=Sick Science|title=Newton's Beads - Cool Science Experiment|date=2009-07-29|url=https://www.youtube.com/watch?v=m-88M75_PCI|access-date=2021-07-24}}</ref> This phenomenon is classically known as Newton's beads.<ref name=":0">{{Cite journal|last1=Martchenko|first1=Ilya|last2=Malinowski|first2=Maciej|last3=Oszmaniec|first3=Michał|date=2011-10-09 |title=Preparation to the Young Physicists' Tournaments' 2012|url=https://ilyam.org/SD_2012_IYPT_Reference_kit_IM_MM_MO_SS_AS.pdf|journal=International Young Physicist Tournament}}</ref>
The effect is most pronounced when using a long ball chain. The higher the jar containing the chain is placed above the ground, the higher the chain will rise above the jar during the "siphoning" phase. As demonstrated in an experiment, when the jar is placed {{convert|30|m}} above the ground and the chain is sufficiently long, the arc of the chain fountain can reach a height of about {{cvt|2.1|m}} above the jar.{{Primary source inline|date=July 2021}}<ref>{{cite AV media|url=https://www.youtube.com/watch?v=UM4lnzhvzdE&t=1800|title=第1期-刘谦郎朗被吊起"命悬一杯" 撒贝宁对大炮求虐【加油！向未来20160703】|language=zh}}</ref>
In 2011, the phenomenon with the rising chain was described as an open problem{{efn|'''Statement of problem 3. String of beads''': "A long string of beads is released from a beaker by pulling a sufficiently long part of the chain over the edge of the beaker. Due to gravity the speed of the string increases. At a certain moment the string no longer touches the edge of the beaker. Investigate and explain the phenomenon.")}} for the 2012 International Young Physicists' Tournament (IYPT).<ref name="IYPT-Problems-2012">{{cite web|title=Problems|url=https://archive.iypt.org/problems/|url-status=live|archive-url=https://web.archive.org/web/20180301044330/http://iypt.org/images/0/05/Problems2012.pdf|archive-date=2018-03-01|website=IYPT archive}}</ref><ref name=":0" />
In 2013, science presenter Steve Mould brought the chain problem to widespread public attention.<ref name="gibney-nature">{{cite journal|last=Gibney|first=Elizabeth|date=2014-01-15 |title=Physicists explain 'gravity-defying' chain trick|url=https://www.nature.com/news/physicists-explain-gravity-defying-chain-trick-1.14523|journal=Nature|doi=10.1038/nature.2014.14523|doi-access=free}}</ref> In a YouTube video,<ref>{{cite web|url=http://www.youtube.com/watch?v=_dQJBBklpQQ |title=Self siphoning beads |date=2013-02-20 |first=Steve |last=Mould |website=YouTube }}</ref> he demonstrated the phenomenon of self-siphoning rising beads, and he then presented his proposed explanation on a BBC show.<ref>{{cite web|url=http://www.youtube.com/watch?v=6ukMId5fIi0 |date=2013-06-27 |title=Amazing bead chain experiment in slow motion |website=YouTube |series=BBC Earth Unplugged}}</ref> This publicity caught the attention of academics John Biggins and Mark Warner of Cambridge University.<ref>{{cite news|url=http://phys.org/news/2014-01-chain-fountain-problem-solving-partnership-video.html |title=Understanding the chain fountain: A problem-solving partnership (w/ Video) |work=Phys.org |date=2014-01-15 }}</ref><ref>{{cite web|url=https://www.science.org/content/article/video-how-chain-fountain-defies-gravity |title=Video: How the 'Chain Fountain' Defies Gravity |first=Lizzie |last=Wade |work=Science |date=2014-01-14 }}</ref>
In 2014, Biggins and Warner published their findings on the problem in ''Proceedings of the Royal Society'', regarding what they called the "chain fountain" or the "Mould effect".<ref name="Royal"/><ref>{{cite web|author=Royal Society|title=Understanding the chain fountain|date=2014-01-15|url=https://www.youtube.com/watch?v=-eEi7fO0_O0|website=YouTube|language=en|access-date=2021-07-24}}</ref><ref>Steve Mould, ''Investigating the "Mould Effect", TEDxNewcastle, https://www.youtube.com/watch?v=wmFi1xhz9OQ''</ref><ref name=gibney-nature />
In 2025, NASA astronaut Donald Pettit tested a bead chain in the zero gravity environment of the International Space Station to test Mould’s hypotheses about the phenomena.<ref>{{Cite web |last=Felton |first=James |date=2025-10-13 |title=NASA Lets YouTuber Steve Mould Test His "Weird Chain Theory" In Space |url=https://www.iflscience.com/nasa-lets-youtuber-steve-mould-test-his-weird-chain-theory-in-space-81148 |access-date=2026-04-20 |website=IFLScience |language=en}}</ref>
== Explanation == {{stack|thumb|Slow-motion video showing chain fountain dynamics.}} A variety of explanations have been proposed as to how the phenomenon can best be explained in terms of kinematic physics concepts such as energy and momentum.<ref>{{cite news |url=https://www.cbsnews.com/news/see-physics-phenomenon-of-self-siphoning-beads/ |title=See physics phenomenon of self siphoning beads |first=William |last=Goodman |work=CBS News |date=2013-06-25 }}</ref><ref>{{cite magazine |url=https://www.wired.com/wiredscience/2013/07/the-physics-of-that-gravity-defying-chain-of-metal-beads/ |title=The physics of that gravity-defying chain of metal beads |first=Aatish |last=Bhatia |date=2013-07-01 |access-date=2014-01-15 |magazine=Wired}}</ref><ref name=":1">{{Cite journal|last1=Flekkøy|first1=Eirik G.|last2=Moura|first2=Marcel|last3=Måløy|first3=Knut J.|date=2018|title=Mechanisms of the Flying Chain Fountain|journal=Frontiers in Physics|volume=6|article-number=84 |language=English|doi=10.3389/fphy.2018.00084|bibcode=2018FrP.....6...84F |issn=2296-424X|hdl=10852/68287|hdl-access=free|doi-access=free}}</ref><ref>{{Cite journal|last=Pantaleone|first=J.|date=2017-05-16|title=A quantitative analysis of the chain fountain|url=https://aapt.scitation.org/doi/10.1119/1.4980071|journal=American Journal of Physics|volume=85|issue=6|pages=414–421|doi=10.1119/1.4980071|issn=0002-9505|arxiv=1910.03125|bibcode=2017AmJPh..85..414P |s2cid=125247401}}</ref>
Biggins and Warner suggest that the origin of the upward force is related to the stiffness of the chain links, and the bending restrictions of each chain joint.<ref name=gibney-nature/><ref name="Royal">{{cite journal |last1=Biggins |first1=J. S. |last2=Warner |first2=M. |doi=10.1098/rspa.2013.0689 |title=Understanding the chain fountain |url=https://royalsocietypublishing.org/doi/10.1098/rspa.2013.0689 |journal=Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences |volume=470 |issue=2163 |article-number=20130689 |year=2014|arxiv=1310.4056 |bibcode=2014RSPSA.47030689B |s2cid=37699566 }}</ref>
Furthermore, because the beads of the chain can drag laterally within the jar across other stationary links, the moving beads of the chain can bounce or jump vertically when they strike the immobile links. This effect contributes to the chain's movement, but is not the primary cause.<ref name="Royal" /><ref name=":1" />
== In non-Newtonian fluids == The self-siphoning phenomenon can be also observed in viscoelastic fluids<ref>{{Cite book |last=Graebel |first=William |url=https://books.google.com/books?id=UZ_6Mm_e3rYC&dq=self+syphoning+polymer+liquids+polyethylene&pg=PA30 |title=Engineering Fluid Mechanics |date=2001-01-19 |publisher=CRC Press |isbn=978-1-56032-733-2 |language=en}}</ref> that are mainly composed of long polymers, like polyethylene glycol.<ref name=":2">{{Cite book |last1=Arney |first1=Helen |url=https://books.google.com/books?id=SgbhDgAAQBAJ&dq=self+syphoning+polymer+liquids+polyethylene&pg=PT141 |title=The Element in the Room: Science-y Stuff Staring You in the Face |last2=Mould |first2=Steve |date=2017-10-05 |publisher=Octopus |isbn=978-1-78840-004-6 |language=en}}</ref><ref>{{Cite web |title=Gravi-Goo: A Self-Siphoning Gel |url=https://stevespangler.com/experiments/gravi-goo/ |access-date=2024-11-13 |website=Steve Spangler |language=en-US}}</ref>
==See also== *Catenary
== Notes == {{notelist|1}}
== References == {{reflist|1}}
==Bibliography== *{{cite journal |title=Understanding the chain fountain |first1=John Simeon |last1=Biggins |first2=Mark |last2=Warner |journal=Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences |date=2013-11-22 |volume=470 |issue=2163 |doi=10.1098/rspa.2013.0689 |arxiv=1310.4056 |bibcode=2014RSPSA.47030689B }}<!--public copy of paper--> *{{cite web |url=http://stevemould.com/siphoning-beads/ |title=Self siphoning beads |work=Steve Mould's nerdy blog |archive-url=https://web.archive.org/web/20130415072431/http://stevemould.com/siphoning-beads/ |archive-date=2013-04-15 |first=Steve |last=Mould |date=2013-02-20 }}
== External links == {{commons category|Self-siphoning beads}} *{{cite web |url=https://isaacphysics.org/questions/chain_fountain |title=The Chain Fountain |website=Isaac Physics |access-date=25 April 2020}} *{{cite web |url=https://demos.smu.ca/demos/mechanics/169-chain-fountain |title=Chain Fountain in Super Slow-Motion |website=SMU Classroom Physics Demos |access-date=10 September 2021}} *{{Cite web|last=Hell|first=Timotheus|date=26 September 2011|title=IYPT 2012 - Problem 3: String of beads (Newton's Beads)|url=https://www.youtube.com/watch?v=uf9IOpZ0tc4&ab_channel=TimotheusHell|access-date=29 July 2021|website=YouTube}} *{{Cite web|last=Mould|first=Steve|title=NASA let me test my weird chain theory in space|url=https://www.youtube.com/watch?v=NtZaP8VMv0c|date=10 October 2025|access-date=10 October 2025|website=YouTube}} {{Non-Newtonian fluids}} Category:Science demonstrations Category:Articles containing video clips fountain Category:Effects of gravity Category:Falling Category:Rheology