Usually, when something gets warmed up, heat tends to spread outward before eventually dissipating. But things are a little different in the world of superfluid quantum gas.<\/p>\n<\/li>\n
For the first time, MIT scientists have successfully imaged how heat actually travels in a wave, known as a \u201csecond sound,\u201d through this exotic fluid.<\/p>\n<\/li>\n
Understanding this dynamic could help answer questions about high-temperature superconductors and neutron stars.<\/p>\n<\/li>\n<\/ul>\n
In the world of average, everyday materials, heat tends to spread out from a localized source. Drop a burning coal into a pot of water, and that liquid<\/a> will slowly rise in temperature before its heat eventually dissipates. But the world is full of rare, exotic materials that don\u2019t exactly play by these thermal rules.<\/p>\n Instead of spreading out as one would expect, these superfluid quantum gasses \u201cslosh\u201d heat side to side\u2014it essentially propagates as a wave<\/a>. Scientists call this behavior a material\u2019s \u201csecond sound\u201d (the first being ordinary sound via a density wave). Although this phenomenon has been observed before, it\u2019s never been imaged. But recently, scientists at the Massachusetts Institute of Technology (MIT) were finally able to capture this movement of pure heat by developing a new method of thermography (a.k.a. heat-mapping).<\/p>\n The results of this study were published in the journal Science<\/a>, and in an university press release<\/a> highlighting the achievement, MIT assistant professor and co-author Richard Fletcher continued the boiling pot analogy to describe the inherent strangeness of \u201csecond sound<\/a>\u201d in these exotic superfluids.<\/p>\n Simplified example of “sloshing” heat in a superfluid compared to a normal fluid. MIT<\/p>\n \u201cIt\u2019s as if you had a tank of water<\/a> and made one half nearly boiling,\u201d Fletcher said. \u201cIf you then watched, the water itself might look totally calm, but suddenly the other side is hot, and then the other side is hot, and the heat goes back and forth, while the water looks totally still.\u201d<\/p>\n These superfluids are created when a cloud of atoms is subjected to ultra-cold temperatures approaching absolute zero<\/a> (\u2212459.67 \u00b0F). In this rare state, atoms behave differently, as they create an essentially friction-free fluid. It\u2019s in this frictionless state that heat has been theorized to propagate like a wave.<\/p>\n \u201cSecond sound is the hallmark of superfluidity, but in ultracold gases so far you could only see it in this faint reflection of the density ripples<\/a> that go along with it,\u201d lead author Martin Zwierlein said in a press statement. \u201cThe character of the heat wave could not be proven before.\u201d<\/p>\n To finally capture this second sound in action, Zweierlein and his team had to think outside the usual thermal box, as there\u2019s a big problem trying to track heat of an ultracold object\u2014it doesn\u2019t emit the usual infrared radiation. So, MIT scientists designed a way to leverage radio frequencies to track certain subatomic particles known as \u201clithium-6 fermions,\u201d which can be captured via different frequencies<\/a> in relation to their temperature (i.e. warmer temperatures mean higher frequencies, and vice versa). This novel technique allowed the researchers to essentially zero in on the \u201chotter\u201d frequencies (which were still very much cold) and track the resulting second wave over time.<\/p>\n This might feel like a big \u201cso what?\u201d After all, when\u2019s the last time you had a close encounter with a superfluid quantum<\/a> gas? But ask a materials scientist or astronomer, and you\u2019ll get an entirely different answer.<\/p>\n While exotic superfluids may not fill up our lives (yet), understanding the properties of second wave movement could help questions regarding high-temperature superconductors<\/a> (again, still at very low temperatures) or the messy physics that lie at the heart of neutron stars<\/a>.<\/p>\n Photo credit: Hearst Owned<\/p>\n Get the Issue<\/a><\/p>\n Photo credit: Hearst Owned<\/p>\n Get the Issue<\/a><\/p>\n Photo credit: Hearst Owned<\/p>\n Get the Issue<\/a><\/p>\n Photo credit: Hearst Owned<\/p>\n Get the Issue<\/a><\/p>\n Photo credit: Hearst Owned<\/p>\n Get the Issue<\/a><\/p>\n Photo credit: Hearst Owned<\/p>\n Get the Issue<\/a><\/p>\n Photo credit: Hearst Owned<\/p>\n Get the Issue<\/a><\/p>\n Photo credit: Hearst Owned<\/p>\n Get the Issue<\/a><\/p>\n Photo credit: Hearst Owned<\/p>\n![\"graphical](\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2025\/08\/993ac57809b3cf18e426b2990d217c41.jpeg\"\/)
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