{"id":202738,"date":"2023-10-24T07:30:21","date_gmt":"2023-10-24T11:30:21","guid":{"rendered":"https:\/\/today.uconn.edu\/?p=202738"},"modified":"2023-10-18T15:09:55","modified_gmt":"2023-10-18T19:09:55","slug":"a-trumpet-fire-and-physics","status":"publish","type":"post","link":"https:\/\/today.uconn.edu\/2023\/10\/a-trumpet-fire-and-physics\/","title":{"rendered":"A Trumpet, Fire, and Physics"},"content":{"rendered":"

In the midst of an infinite scroll \u2013 you know, the kind where you\u2019re lying on the couch after a long day just thumbing through your social media feed, watching whatever random video clip pops up next \u2013 was this little recording of a trumpeter<\/a>.<\/p>\n

He\u2019s wearing a red shirt and sitting at a long metal tube, poised to play, with the bell of his brass trumpet snugged right up to the end of the tube.<\/p>\n

The tube is on fire.<\/p>\n

As the trumpeter \u2013 who I later learned is the musician Moises Alves<\/a> \u2013 begins to play, the flames start to dance. Higher. Lower. Faster. Slower. Parallel columns of flickering fire seemingly floating atop the tube.<\/p>\n

The video abruptly ends with a chaotic panning shot to the floor, like someone forgot to stop their phone while still recording, and the whole thing is over in 30 seconds. I watched it again and again and again.<\/p>\n

It was mesmerizing.<\/p>\n

I showed my spouse. I showed coworkers in University Communications at UConn<\/a>. Have you seen this viral fire trumpet video? It\u2019s so amazing to watch, but how does this even work? Sound waves or something, right?<\/p>\n

Could someone actually explain the science behind what\u2019s making the fire dance atop that tube?<\/p>\n

As it turns out, someone at UConn certainly can \u2013 and was eager to do so.<\/p>\n

\u201cWith a Rubens\u2019 tube, when you play certain frequencies, you set up what\u2019s called a standing wave,\u201d says George Gibson<\/a>, a professor and head of the Department of Physics in UConn\u2019s College of Liberal Arts and Sciences.<\/p>\n

\u201cA standing wave is a pattern of nodes, where nothing\u2019s happening, and antinodes, where there\u2019s a lot of action,\u201d he says, \u201cand so, the flames respond to whether it\u2019s at a node or an antinode. That\u2019s why you develop a stable pattern of the flames either being high or low or high or low.\u201d<\/p>\n

All waves \u2013 including sound waves, Gibson explains \u2013 are a disturbance in a medium.<\/p>\n

\u201cThe medium has to be able to return to equilibrium,\u201d he says, \u201cand there\u2019s some force which does that. For sound waves, the restoring force is pressure.\u201d<\/p>\n

The cavity inside the Rubens\u2019 tube isn\u2019t empty. It\u2019s piped full of gas \u2013 in this case, flammable propane gas, which has a different density than the air we breathe. As sound waves are projected into the tube by a speaker, or from the bell of a trumpet, they bounce off the opposite end of the tube and interfere with each other, creating a standing wave with regions of high and low pressure.<\/p>\n

Those regions of pressure will cause the fire burning off the propane from holes drilled along the top of the tube to move based on where the nodes and antinodes are positioned at a given time within the tube.<\/p>\n

The height and intensity of the flame depends on factors like the volume of the sound and the amount of gas pressure within the tube. The length of the tube itself will determine what frequency is resonant inside of it to form the standing wave.<\/p>\n

Gibson designed and teaches a course at UConn on the physics of music. In fact, he was teaching it this summer as an online class<\/a> when we reached out to him about an idea to recreate this viral video with a UConn expert explaining the science behind it.<\/p>\n

Gibson isn\u2019t just an expert on the physics of music, he\u2019s also a researcher, a student of physics history, and a proponent of using music as a way to learn about physics.<\/p>\n

\u201cWith classical mechanics, which deals with objects and projectiles, unfortunately a lot of people\u2019s common sense isn\u2019t correct,\u201d he says. \u201cIf you toss a baseball up, at the top, when it turns around and starts coming down, if you ask what\u2019s the acceleration at the top, most people will say zero, because it\u2019s not moving. But it\u2019s not zero. It\u2019s still the same acceleration. So, you have to break down people\u2019s intuition and common sense, which can be difficult.\u201d<\/p>\n

Music is different, though \u2013 most people haven\u2019t really thought much about the waves that carry the sounds we hear or the music we enjoy.\u201cThey don\u2019t have any preconceived notions, and their intuition is usually correct,\u201d Gibson says. \u201cAnd so, it actually makes it very easy to make a connection and to teach physics, because modern physics is basically wave theory.\u201d<\/p>\n

On a deeper level, it is not surprising to Gibson that almost all of the founders of quantum mechanics<\/a> had connections with music \u2013 they played music themselves, or studied consonance and dissonance<\/a>. The Rubens\u2019 tube itself is named for a German physicist \u2013 Heinrich Rubens<\/a> \u2013 who Gibson says doesn\u2019t get enough credit for his contributions to the origins of quantum mechanics.<\/p>\n

\u201cIf you have an electric stove, and you look at the coils, as you turn it on and it starts heating up, it\u2019s first a dull red, then a brighter red, then orange, then yellow, then even white as you get hotter and hotter,\u201d says Gibson.<\/p>\n

But in the 1890s, nobody had any clue as to how you got from the temperature to the color.<\/p>\n

\u201cIt was so fundamental,\u201d Gibson says. \u201cHeinrich Rubens was very interested in that. He studied the infrared tail of the spectrum very accurately. He was invited to the house of a fellow German physicist, Max Planck, for a dinner party, and he showed him his data. Max Planck got so excited about it, he stayed up all night and actually came up with the first equation that described what is called the \u2018blackbody spectrum<\/a>\u2019.\u201d<\/p>\n

Planck, Gibson shares, is said to have woken his wife in the middle of the night playing Beethoven\u2019s \u201cOde to Joy\u201d excitedly on the piano as he formulated the Nobel-prize winning equation that contained the first clues as to the strange nature of quantum mechanics<\/a>.<\/p>\n

But if Rubens was so busy helping to build the foundations of modern physics, why did he design this dancing fire tube?<\/p>\n

Because he was also an educator, Gibson explains, and the tube offered a visual means of demonstrating otherwise invisible sound waves.<\/p>\n

Rubens used it to teach.<\/p>\n

And as it turns out, a student group on campus, the UConn Engineering Ambassadors<\/a>, has a Rubens\u2019 tube that they use for that same original educational purpose \u2013 their Rubens\u2019 tube is part of a series of STEM demonstrations they offer to K-through-12 schools around Connecticut.<\/p>\n

When we assembled their Rubens\u2019 tube \u2013 first for a demonstration at UConn\u2019s Fire Station and later on the darkened stage at the UConn School of Music\u2019s von der Mehden Recital Hall<\/a> \u2013 those in attendance got to view this wonder of sound and pressure and waves close-up. And to learn about the science behind the fire that danced to the trumpet\u2019s melody.<\/p>\n

And even then, knowing how it worked exactly, and knowing what was happening inside of that tube, it was mesmerizing.<\/p>\n

Very special thanks to Professor George Gibson, the UConn Engineering Ambassadors, UConn School of Fine Arts Graduate Fellow <\/em>Eric Rizzo<\/em><\/a>, UConn Music Professor <\/em>Louis Hanzlik<\/em><\/a>, the <\/em>UConn Fire Department<\/em><\/a>, and the von der Mehden Recital Hall for their invaluable contributions to this project.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

In the case of a recent viral video of a trumpeter playing into a tube that\u2019s on fire, making the flames dance higher and lower in time to the music, we asked experts at UConn to explain just how the device \u2013 called a Rubens\u2019 tube \u2013 worked<\/p>\n","protected":false},"author":134,"featured_media":205917,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"video","meta":{"_acf_changed":false,"_crdt_document":"","wds_primary_category":0,"wds_primary_series":0,"wds_primary_attribution":0,"footnotes":""},"categories":[1866,2226,1914,2235,2227,70],"tags":[],"magazine-issues":[],"coauthors":[2168,2414],"class_list":["post-202738","post","type-post","status-publish","format-video","has-post-thumbnail","hentry","category-engr","category-clas","category-sfa","category-today-homepage","category-uconn-edu-homepage","category-video","post_format-post-format-video"],"pp_statuses_selecting_workflow":false,"pp_workflow_action":"current","pp_status_selection":"publish","acf":[],"publishpress_future_action":{"enabled":false,"date":"2026-04-12 23:54:42","action":"change-status","newStatus":"draft","terms":[],"taxonomy":"category","extraData":[]},"publishpress_future_workflow_manual_trigger":{"enabledWorkflows":[]},"_links":{"self":[{"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/posts\/202738","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/users\/134"}],"replies":[{"embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/comments?post=202738"}],"version-history":[{"count":4,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/posts\/202738\/revisions"}],"predecessor-version":[{"id":205985,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/posts\/202738\/revisions\/205985"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/media\/205917"}],"wp:attachment":[{"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/media?parent=202738"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/categories?post=202738"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/tags?post=202738"},{"taxonomy":"magazine-issue","embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/magazine-issues?post=202738"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/coauthors?post=202738"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}