Editing Sonoluminescence (section)

===Other proposals===

====Quantum explanations====
An unusually exotic hypothesis of sonoluminescence, which has received much popular attention, is the Casimir energy hypothesis suggested by noted physicist [[Julian Schwinger]]<ref>{{cite web | first = Julian | last = Schwinger | name-list-style = vanc |url=http://www.infinite-energy.com/iemagazine/issue1/colfusthe.html |title= Cold Fusion: A History of Mine |publisher=Infinite-energy.com |date=1989-03-23 |access-date=2012-11-14}}</ref> and more thoroughly considered in a paper by [[Claudia Eberlein]]<ref>{{cite journal | vauthors = Eberlein C | title = Theory of quantum radiation observed as sonoluminescence. | journal = Physical Review A | date = April 1996 | volume = 53 | issue = 4 | pages = 2772–2787 | doi = 10.1103/PhysRevA.53.2772| pmid = 9913192 | url = https://pdfs.semanticscholar.org/27f5/25c6fca3f8eff0605a6f71c75ce2a677ce7e.pdf | archive-url = https://web.archive.org/web/20190323091226/https://pdfs.semanticscholar.org/27f5/25c6fca3f8eff0605a6f71c75ce2a677ce7e.pdf | url-status = dead | archive-date = 2019-03-23 | bibcode = 1996PhRvA..53.2772E | arxiv = quant-ph/9506024 | s2cid = 10902274 }}</ref> of the [[University of Sussex]]. Eberlein's paper suggests that the light in sonoluminescence is generated by the vacuum within the bubble in a process similar to [[Hawking radiation]], the radiation generated at the [[event horizon]] of [[black hole]]s. According to this vacuum energy explanation, since quantum theory holds that vacuum contains [[virtual particle]]s, the rapidly moving interface between water and gas converts virtual photons into real photons. This is related to the [[Unruh effect]] or the [[Casimir effect]]. The argument has been made that sonoluminescence releases too large an amount of energy and releases the energy on too short a time scale to be consistent with the vacuum energy explanation,<ref>{{cite arXiv | vauthors = Milton KA | title = Dimensional and Dynamical Aspects of the Casimir Effect: Understanding the Reality and Significance of Vacuum Energy | date = September 2000 | eprint = hep-th/0009173 }}</ref> although other credible sources argue the vacuum energy explanation might yet prove to be correct.<ref>{{cite arXiv | vauthors = Liberati S, Belgiorno F, Visser M | title = Comment on "Dimensional and dynamical aspects of the Casimir effect: understanding the reality and significance of vacuum energy" | eprint = hep-th/0010140v1 | year = 2000 }}</ref>

====Nuclear reactions====
{{Main|Bubble fusion}}
Some have argued that the Rayleigh–Plesset equation described above is unreliable for predicting bubble temperatures and that actual temperatures in sonoluminescing systems can be far higher than 20,000 kelvins. Some research claims to have measured temperatures as high as 100,000 kelvins and speculates temperatures could reach into the millions of kelvins.<ref name="pmid18851095">{{cite journal | vauthors = Chen W, Huang W, Liang Y, Gao X, Cui W | title = Time-resolved spectra of single-bubble sonoluminescence in sulfuric acid with a streak camera | journal = Physical Review E | volume = 78 | issue = 3 Pt 2 | pages = 035301 | date = September 2008 | pmid = 18851095 | doi = 10.1103/PhysRevE.78.035301 | bibcode = 2008PhRvE..78c5301C }}
*{{cite web |author=Tim Reid |date=15 October 2008 |title=Sonoluminescence: Baking bubbles |website=Nature China |url=http://www.nature.com/nchina/2008/081015/full/nchina.2008.241.html |archive-url=https://web.archive.org/web/20131212070822/http://www.nature.com/nchina/2008/081015/full/nchina.2008.241.html |archive-date=2013-12-12}}</ref> Temperatures this high could cause [[thermonuclear fusion]]. This possibility is sometimes referred to as [[bubble fusion]] and is likened to the implosion design used in the fusion component of [[thermonuclear weapon]]s.

Experiments in 2002 and 2005 by [[Rusi Taleyarkhan|R. P. Taleyarkhan]] using deuterated [[acetone]] showed measurements of [[tritium]] and neutron output consistent with fusion. However, the papers were considered low quality and there were doubts cast by a report about the author's scientific misconduct. This made the report lose credibility among the scientific community.<ref name="latimes">[http://www.latimes.com/news/nationworld/nation/la-sci-misconduct19-2008jul19,0,1765099.story Purdue physicist found guilty of misconduct], Los Angeles Times, July 19, 2008, Thomas H. Maugh II</ref><ref name="Nature_India_2008">{{cite journal | vauthors = Jayaraman KS | title = Bubble fusion discoverer says his science is vindicated | journal = [[Nature India]] | doi = 10.1038/nindia.2008.271 | year = 2008 }}</ref><ref name="SFC">{{cite news | agency=Associated Press | url = https://www.usatoday.com/tech/science/2008-08-27-purdue-scientist_N.htm | title = Purdue reprimands fusion scientist for misconduct | work=USA Today | date = August 27, 2008 | access-date = 2010-12-28 }}</ref>

On January 27, 2006, researchers at [[Rensselaer Polytechnic Institute]] claimed to have produced fusion in sonoluminescence experiments.<ref>{{cite web|url=http://news.rpi.edu/luwakkey/1322 |title=RPI: News & Events – New Sonofusion Experiment Produces Results Without External Neutron Source |publisher=News.rpi.edu |date=2006-01-27 |access-date=2012-11-14}}</ref><ref>{{cite web|url=https://www.sciencedaily.com/releases/2006/01/060130155542.htm |title=Using Sound Waves To Induce Nuclear Fusion With No External Neutron Source |publisher=Sciencedaily.com |date=2006-01-31 |access-date=2012-11-14}}</ref>