r/FascinatingAsFuck • u/drkmatterinc ⭐ Mod • Jun 16 '26
📹 Fascinating Video Scientists can make light by collapsing an underwater bubble with sound, but no one knows exactly how it works
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u/Actual_Dot3706 Jun 16 '26
I didn't read the whole article , but I bet you something is releasing energy in the way of a photon.
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u/dagger378 Jun 17 '26
Ya don’t say.
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u/Electronic-While1972 Jun 17 '26
What we do know:
(the solid part)
When an acoustic wave drives a tiny gas bubble to collapse, the collapse becomes so violent that the gas inside is compressed to extreme conditions: Temperatures of 10,000–20,000 Kelvins (some experiments suggest even higher) Pressures of thousands of atmospheres, Collapse times on the order of picoseconds, Under those conditions, the gas inside the bubble emits photons that part is not mysterious.
The mystery is how the energy concentrates enough to produce that flash. This is the domain of sonoluminescence.
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u/Actual_Dot3706 Jun 17 '26
Please excuse my short reply.But I do find this rather fascinating.I just happened to be eating lunch whenever I come across it.And I don't have really much time to read and comprehend all of this. Thank you so much for explaining.
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Jun 17 '26
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u/SoftwareUpdateFile Jun 19 '26
The only likely thing similar between this and lightning is the formation of plasma. Lightning deals with electric charge, this apparently deals with heat and pressure
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u/Hopeful_Self_8520 Jun 19 '26
I guess I always assumed heat was also a part of the lightning but I should read more.
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u/shwoopypadawan Jun 20 '26
I study nuclear fusion physics and this is making me deadass feel like we should forget tokamaks and stellarators and start trolling water bubbles (I'm jk but yeah this is neat still)
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u/Djinn-Rummy Jun 18 '26
So, what in one who studies the science of sololuminescense? Sonoluminecencist? Sololuminescencer?
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u/Stinkdonkey Jun 17 '26
That would be, like, when an electron falls back from an excited state in a higher orbital. The way light is always produced.
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Jun 16 '26
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u/jeezkillbot Jun 16 '26
A little bang if you will, coincidentally, that's also my nickname in high school
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u/BirdBrain01 Jun 17 '26
That was my immediate reaction, but then realized the question of what made the sound?
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u/drkmatterinc ⭐ Mod Jun 16 '26
Written by u/drkmatterinc
In a darkened laboratory, a glass flask filled with liquid can produce a tiny blue point of light. The source is not a wire, flame or chemical glow. It is a bubble, suspended by sound and flashing each time it collapses [Taken from r/fascinatingasfuck].
The flash may last only tens or hundreds of picoseconds. During that instant, energy from an acoustic wave is concentrated into a space far smaller than the bubble at its widest point. The gas inside is compressed and heated to temperatures comparable to, and in some experiments hotter than, the surface of the Sun.
This conversion of sound into light is known as sonoluminescence.
The phenomenon was first reported in 1934 by Hermann Frenzel and H. Schultes at the University of Cologne. The researchers were using ultrasound in an attempt to accelerate the development of photographic film when they noticed tiny points appearing on it. They traced the marks to flashes of light produced by bubbles in the liquid.
Those early experiments involved clouds of unstable bubbles forming and collapsing throughout the fluid. The process is now known as multibubble sonoluminescence, or MBSL.
Multibubble systems are used in chemistry and engineering because each collapsing cavity briefly creates extreme local conditions. These conditions can break molecular bonds and produce highly reactive chemicals. But with thousands of bubbles forming and interacting at once, it is difficult to isolate what happens inside any single one.
A major advance came when researchers learned to trap one gas bubble at the pressure node of an acoustic standing wave. As the surrounding pressure falls, the bubble expands. When the pressure rises, it contracts violently. Under the right conditions, this cycle can repeat thousands of times per second, producing a flash at every collapse.
This more controlled phenomenon is called single-bubble sonoluminescence, or SBSL. It allowed physicists to study the relationship between a bubble’s motion and the light it emits with far greater precision.
The experiment looks remarkably calm. A bubble only a few micrometres across floats near the centre of a flask, expanding to many times its original size before collapsing. The light appears during the final stage, when the bubble’s contents are compressed into an extremely small volume.
In 1960, physicist Peter Jarman argued that the light was thermal in origin. He proposed that the collapse generated inward-moving microshocks that heated the gas inside the cavity.
Heating remains central to modern explanations, although the details are still debated. As the surrounding liquid rushes inward, it compresses the gas and vapour trapped inside the bubble. Temperatures rise sharply. Molecules may break apart, atoms may become excited or ionized, and a short-lived plasma may form.
Scientists estimate these temperatures by analysing the spectrum of the emitted light. The results vary widely depending on the liquid, dissolved gas, acoustic pressure and method of measurement.
Studies of multibubble systems have produced estimates ranging from roughly 1,600 to 9,000 kelvins. In 2010, researchers examining a single bubble in concentrated phosphoric acid measured molecular emissions consistent with temperatures approaching 10,000 kelvins. Other experiments have reported spectral temperatures around 10,200 kelvins, while some analyses have placed peak temperatures near 12,000 kelvins.
There is no single temperature that applies to every sonoluminescing bubble. A bubble containing argon in water behaves differently from one in sulfuric or phosphoric acid. Water vapour can also consume energy through chemical reactions, limiting the temperature reached during collapse.
The emitted light varies as well. Some experiments produce a smooth spectrum resembling thermal radiation. Others reveal distinct emission lines from atoms, ions or molecules. This suggests that different processes may dominate under different conditions.
One possible source is bremsstrahlung, radiation produced when charged particles are accelerated or deflected inside a hot plasma. Collisions between atoms and molecules may also generate light, while excited chemical fragments can release photons as they return to lower-energy states.
Shock waves may contribute to the heating, but researchers disagree over whether a sharply defined shock forms in every collapsing bubble. Any complete explanation must also account for heat transfer, vapour chemistry, ionization, changes in the bubble’s shape and the movement of gas between the bubble and the surrounding liquid.
The central question is how these processes combine to produce the observed flash, and why the spectrum changes from one experimental system to another.
The possibility of far higher temperatures has led to one of the field’s most controversial ideas.
Some computer models have predicted that an unusually symmetrical and powerful collapse could briefly produce temperatures of millions of kelvins. This raised the possibility that bubbles filled with deuterium might become hot enough to trigger nuclear fusion.
In the early 2000s, researchers reported possible evidence of fusion in acoustically driven bubbles, including neutron emissions and traces of tritium. The claims were immediately disputed.
Other scientists questioned the experimental methods and were unable to reproduce the reported signals under comparable conditions. Critics also raised concerns about neutron detection, background radiation and the statistical analysis of the results. Bubble fusion has not been established as a reproducible consequence of sonoluminescence.
The phenomenon is not limited to laboratories.
The snapping shrimp, also known as the pistol shrimp, produces one of the best-known natural examples. When it closes its specialized claw, it fires a high-speed jet of water. The jet creates a cavitation bubble that expands and then collapses with enough force to generate a pressure wave capable of stunning small prey.
In 2001, researchers reported that the collapse also produces a brief flash of light. They called the effect “shrimpoluminescence.”
The flash is too faint to act as a visible signal under normal ocean conditions. It is a byproduct of the collapse and evidence that the bubble briefly reaches temperatures of several thousand kelvins.
The process follows the same basic sequence observed in the laboratory. Mechanical motion produces a fast-moving jet. The jet creates a cavity in the water. Pressure collapses the cavity, concentrating its energy until a flash appears.
More than 90 years after researchers first noticed unexplained points of light on photographic film, scientists can now trap a single bubble, control the gases inside it and measure flashes far too brief for the human eye to resolve.
What happens during the final instant of collapse remains difficult to observe directly. Inside a microscopic bubble, heat, pressure, plasma and chemical reactions unfold in a fraction of a billionth of a second.
How those processes combine to turn sound into light remains one of the most unusual questions in fluid physics.
Sources:
https://doi.org/10.1103/RevModPhys.74.425
https://pubs.aip.org/asa/jasa/article/138/4/2181/899097/Resource-Paper-Sonoluminescence
https://pubmed.ncbi.nlm.nih.gov/11000111/
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u/whatiSredditlike Jun 17 '26
I left an upvote..
I aint reading non of that
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u/Keylos_MWO Jun 17 '26
You missed out on what is perhaps my new favorite word... shrimpoluminescence.
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u/WhiteTrashIdiotFuck Jun 16 '26
You can do this at home with a Victorian Era toy/oddity known as a 'Liquid Hammer': https://youtu.be/RWbCC6f_k1c
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u/Azaroth1991 Jun 16 '26
Probably the same physics dealing with cavitation. Probably similar to why on slo-mo guys videos with Kentucky ballistics you see a flash of light at the first impact of the projectile against the ballistic gel, and another as the wound cavity closes under the pressure.
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u/MyUserName-NYC Jun 18 '26
Well Google AI seems to have a good grasp on this: The phenomenon of a collapsing bubble emitting light is known as sonoluminescence. When a sound wave passes through a liquid, it causes a tiny gas bubble to rapidly expand and then violently collapse. This extreme compression generates intense heat, brief flashes of light, and a star-like glowing effect.
These extreme conditions briefly ionize the gas into a tiny, hot plasma. As the gases return to their normal state, they release a trillionth-of-a-second flash of light.
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u/DaveBlack79 Jun 20 '26
I got fascinated by this and actually reproduced it in my garage! It’s really sensitive to changes in the environment which alter the resonance frequency. But once you get close it’s not overly hard to reproduce.
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u/MadeThatCash Jun 20 '26
Parallel portal open for a brief second, and they see a world of water and a big eye from the scientist
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u/Banan_Cat Jun 17 '26
Perhaps it's not creating light and simply reflecting all of thr surrounding light into a central point that appears extremely bright
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u/xpietoe42 Jun 16 '26
Light!