6 ms·

Why does collapsing a bubble with a sound wave produce light?

21 points by akshatjiwan 1y ago

HPsquared 1y ago
I suppose it would also produce nitrogen oxides.
- akshatjiwan 1y ago
  Very likely. The hot plasma generated would form oxides when it's cooled. I read a few papers a while back focussed around generating ammonia and other nitrogenous compounds. I can't find the link to the one I read but apparently other researchers are doing something simillar https://arxiv.org/html/2505.23850v1 https://arxiv.org/html/2505.23850v1 In air bubbles NOx would be likely but it would probably lead to nitric acid production after reacting with water. Here's a paper by NASA that pretty much confirms your intuition https://ntrs.nasa.gov/api/citations/20050215681/downloads/20050215681.pdf https://ntrs.nasa.gov/api/citations/20050215681/downloads/20...
  - HPsquared 1y ago
    Interesting. Nitric acid could be a chemical signature that could be measured, then. Maybe ozone also? I'm thinking equipment monitoring for cavitation.
    - akshatjiwan 1y ago
      Absolutely! Ozone is produced as a byproduct but I don't have any refrences at hand. More generally it can be said reactive oxygen species are produced as an intermediary that turn into several compounds as plasma is cooled. Whatever gas you make bubbles from is going to be ionised(plasma is created during cavitation) and it's going to produce a cocktail of chemicals inside as it cools below ionisation temperature. Many of these are shortlived eg oxygen reacts with hydrogen or nitrogen to form more stable compounds but some intermediaries can be stable and be detected. The absolute max amount of nitric acid you can get for example is proportional to the amount of air dissolved in water. If you cavitate entire 1L of water max HNo3 you can get is about 20mg. Realistically it's not possible to cavitate such a large volume of water at once and there's a competition among reactants to form other products eg oxygen is going to used for hydrogen peroxide as well. Very sensitive instruments are used to detect these. This is studied in sonochemistry —using bubbles to drive chemical reactions.Not enough for large scale production but small doses of chemicals — mostly radicals can be delivered by bubbles making it useful as a disinfectant.
tobr 1y ago
Holy hypertext, this is a hard-to-read post.
- dfedbeef 1y ago
  Internet 5.0, every word is a link. Scrolling is done with your brain, clicking is done with by flexing your nostrils
  - unshavedyak 1y ago
    Sneezes are security risks. Sounds neat
- lloydatkinson 1y ago
  I sometimes wonder what people are thinking (or apparently not thinking) when they link to their personal sites and blogs and it's totally unreadable. I think they are so used to it they don't see any problems with it.
  - defanor 1y ago
    It looks a bit messy to me, neglecting usage of hyperlinks, but at the same time highly legible (does not mess with fonts, colors, or the layout too much), lightweight, works without JS, does not geo-block me or require to solve captchas, not paywalled, not blocked here, is straight to the point. So perhaps still more easily readable than most of the other submissions found on the HN front page.
- akshatjiwan 1y ago
  Apologies. I write everything in plain text on my mobile and just copy paste it to blogger/fb. Most platforms automatically create clickable links (hn also does that) but apparently blogger does not do it. I like full links on the post because it makes it easier to backup. If I embed them in anchor tags they'd have to be parsed from the formatted web page or I'd have to store data as an html file. I don't want to do that. md is a good alternative and slowly I'm migrating my files to GitHub.
smusamashah 1y ago
Is there a better link?
- uvaursi 1y ago
  Are Reddit posts allowed to be submitted to HN?
_tk_ 1y ago
What?
sophrosyne42 1y ago
> 1. How do you extract energy out of it? It's surrounded in a water bath that would evaporate leading to cessation of bubble formation. Sounds like a perfect use-case for the tried and true steam turbine. You can never beat a steam turbine.
- sandworm101 1y ago
  Steam is the medium, not a fuel. Low-temp steam just above the boiling point doesnt carry much energy. It would also be very wet, which plays havoc with mechanical systems. I dont see how this tech could ever produce the hot/dry steam needed for turbines.
- sodaclean 1y ago
  Sonoluminescence is not power positive. Fusion would be trivial to prove with a neutron detector- so saying "theres debate" is arguably dishonest. Sonoluminescence is weird and awesome enough as is: cavitation that produces light.
  - akshatjiwan 1y ago
    Researchers have reported neutron detection but these results have not been reproduced and some scientists have attributed this detection to 'noise'. Bubbles are tiny they have very small amount of gas in them so detecting that is not exactly straightforward... I think for example a in a 1um radius bubble the total mass of gas would be ~ 10^-18kg. Personally I doubt fusion occurs inside bubbles. Even if we take the highest reported temp 30000K that's way below what's required for fusion. Also bubble literature is full of fantastic claims—one that comes to mind is assertion that pressures of around 10Gpa can be generated which seems highly improbable because that's likely to induce phase change in the fluid. However it's quite possible that I'm wrong. Because bubble science keeps on throwing new surprises.
    - sodaclean 1y ago
      Are you agreeing or disagreeing with it being trivial to check if theres fusion? > However it's quite possible that I'm wrong. Because bubble science keeps on throwing new surprises. Ultimately that's my assertion. No need for exaggerated/optimistic claims when something interesting turns up about it on a regular basis.
docfort 1y ago
This was a passion of mine decades ago, but Putterman's lab jump-started interest after the cold fusion debacles. Some fun videos and pictures on the lab website. https://acoustics-research.physics.ucla.edu/sonoluminescence/ https://acoustics-research.physics.ucla.edu/sonoluminescence...
ortusdux 1y ago
A lot of work goes into minimizing cavitation in marine systems as it tends to waste energy and cause damage to propellers. That being said, there has been a lot of research lately into using sustained cavitation to purify and distil water. The energy released can be enough to boil water, kill pathogens, and generate free radicals to further sterilize the water. https://iwaponline.com/wst/article/86/2/302/89569/Hydrodynamic-cavitation-as-an-efficient-water https://iwaponline.com/wst/article/86/2/302/89569/Hydrodynam...
NoSalt 1y ago
I may not be a working professional in the field of physics - I only had a couple of classes in college - but I absolutely love physics! It seems like magic, and when you learn how it works, you feel like a magician. It's awesome!
- akshatjiwan 1y ago
  It certainly is a great hobby. I'm not a physicist either but I keep reading papers and taking courses on YT about areas I'm interested in — Materials science,plasma, Electrostatics,fluids,thermodynamics etc. Good thing is science doesn't change like tech. Once you learn something it's for life. No need to keep learning new frameworks/tools every year. It's stable and yet immensely flexible. With AI research and studying has become a lot easier. Give it a try if you're interested.Now is a great time to start.

21 points by akshatjiwan 1y ago

HPsquared 1y ago

I suppose it would also produce nitrogen oxides.

akshatjiwan 1y ago
Very likely. The hot plasma generated would form oxides when it's cooled. I read a few papers a while back focussed around generating ammonia and other nitrogenous compounds. I can't find the link to the one I read but apparently other researchers are doing something simillar https://arxiv.org/html/2505.23850v1 https://arxiv.org/html/2505.23850v1 In air bubbles NOx would be likely but it would probably lead to nitric acid production after reacting with water. Here's a paper by NASA that pretty much confirms your intuition https://ntrs.nasa.gov/api/citations/20050215681/downloads/20050215681.pdf https://ntrs.nasa.gov/api/citations/20050215681/downloads/20...
- HPsquared 1y ago
  Interesting. Nitric acid could be a chemical signature that could be measured, then. Maybe ozone also? I'm thinking equipment monitoring for cavitation.
  - akshatjiwan 1y ago
    Absolutely! Ozone is produced as a byproduct but I don't have any refrences at hand. More generally it can be said reactive oxygen species are produced as an intermediary that turn into several compounds as plasma is cooled. Whatever gas you make bubbles from is going to be ionised(plasma is created during cavitation) and it's going to produce a cocktail of chemicals inside as it cools below ionisation temperature. Many of these are shortlived eg oxygen reacts with hydrogen or nitrogen to form more stable compounds but some intermediaries can be stable and be detected. The absolute max amount of nitric acid you can get for example is proportional to the amount of air dissolved in water. If you cavitate entire 1L of water max HNo3 you can get is about 20mg. Realistically it's not possible to cavitate such a large volume of water at once and there's a competition among reactants to form other products eg oxygen is going to used for hydrogen peroxide as well. Very sensitive instruments are used to detect these. This is studied in sonochemistry —using bubbles to drive chemical reactions.Not enough for large scale production but small doses of chemicals — mostly radicals can be delivered by bubbles making it useful as a disinfectant.

tobr 1y ago

Holy hypertext, this is a hard-to-read post.

dfedbeef 1y ago
Internet 5.0, every word is a link. Scrolling is done with your brain, clicking is done with by flexing your nostrils
- unshavedyak 1y ago
  Sneezes are security risks. Sounds neat
lloydatkinson 1y ago
I sometimes wonder what people are thinking (or apparently not thinking) when they link to their personal sites and blogs and it's totally unreadable. I think they are so used to it they don't see any problems with it.
- defanor 1y ago
  It looks a bit messy to me, neglecting usage of hyperlinks, but at the same time highly legible (does not mess with fonts, colors, or the layout too much), lightweight, works without JS, does not geo-block me or require to solve captchas, not paywalled, not blocked here, is straight to the point. So perhaps still more easily readable than most of the other submissions found on the HN front page.
akshatjiwan 1y ago
Apologies. I write everything in plain text on my mobile and just copy paste it to blogger/fb. Most platforms automatically create clickable links (hn also does that) but apparently blogger does not do it. I like full links on the post because it makes it easier to backup. If I embed them in anchor tags they'd have to be parsed from the formatted web page or I'd have to store data as an html file. I don't want to do that. md is a good alternative and slowly I'm migrating my files to GitHub.

smusamashah 1y ago

Is there a better link?

uvaursi 1y ago
Are Reddit posts allowed to be submitted to HN?

_tk_ 1y ago

What?

sophrosyne42 1y ago

> 1. How do you extract energy out of it? It's surrounded in a water bath that would evaporate leading to cessation of bubble formation. Sounds like a perfect use-case for the tried and true steam turbine. You can never beat a steam turbine.

sandworm101 1y ago
Steam is the medium, not a fuel. Low-temp steam just above the boiling point doesnt carry much energy. It would also be very wet, which plays havoc with mechanical systems. I dont see how this tech could ever produce the hot/dry steam needed for turbines.
sodaclean 1y ago
Sonoluminescence is not power positive. Fusion would be trivial to prove with a neutron detector- so saying "theres debate" is arguably dishonest. Sonoluminescence is weird and awesome enough as is: cavitation that produces light.
- akshatjiwan 1y ago
  Researchers have reported neutron detection but these results have not been reproduced and some scientists have attributed this detection to 'noise'. Bubbles are tiny they have very small amount of gas in them so detecting that is not exactly straightforward... I think for example a in a 1um radius bubble the total mass of gas would be ~ 10^-18kg. Personally I doubt fusion occurs inside bubbles. Even if we take the highest reported temp 30000K that's way below what's required for fusion. Also bubble literature is full of fantastic claims—one that comes to mind is assertion that pressures of around 10Gpa can be generated which seems highly improbable because that's likely to induce phase change in the fluid. However it's quite possible that I'm wrong. Because bubble science keeps on throwing new surprises.
  - sodaclean 1y ago
    Are you agreeing or disagreeing with it being trivial to check if theres fusion? > However it's quite possible that I'm wrong. Because bubble science keeps on throwing new surprises. Ultimately that's my assertion. No need for exaggerated/optimistic claims when something interesting turns up about it on a regular basis.

docfort 1y ago

This was a passion of mine decades ago, but Putterman's lab jump-started interest after the cold fusion debacles. Some fun videos and pictures on the lab website. https://acoustics-research.physics.ucla.edu/sonoluminescence/ https://acoustics-research.physics.ucla.edu/sonoluminescence...

ortusdux 1y ago

A lot of work goes into minimizing cavitation in marine systems as it tends to waste energy and cause damage to propellers. That being said, there has been a lot of research lately into using sustained cavitation to purify and distil water. The energy released can be enough to boil water, kill pathogens, and generate free radicals to further sterilize the water. https://iwaponline.com/wst/article/86/2/302/89569/Hydrodynamic-cavitation-as-an-efficient-water https://iwaponline.com/wst/article/86/2/302/89569/Hydrodynam...

NoSalt 1y ago

I may not be a working professional in the field of physics - I only had a couple of classes in college - but I absolutely love physics! It seems like magic, and when you learn how it works, you feel like a magician. It's awesome!

akshatjiwan 1y ago
It certainly is a great hobby. I'm not a physicist either but I keep reading papers and taking courses on YT about areas I'm interested in — Materials science,plasma, Electrostatics,fluids,thermodynamics etc. Good thing is science doesn't change like tech. Once you learn something it's for life. No need to keep learning new frameworks/tools every year. It's stable and yet immensely flexible. With AI research and studying has become a lot easier. Give it a try if you're interested.Now is a great time to start.