{{short description|Type of hypothetical particle}} {{use dmy dates|date=January 2026}} {{About|the hypothetical particle|the album|Strangelet (album)}} A '''strangelet''' (pronounced {{IPAc-en|ˈ|s|t|ɹ|eɪ|n|dʒ|.|l|ɪ|t}}) is a hypothetical particle consisting of a bound state of roughly equal numbers of up, down, and strange quarks. An equivalent description is that a strangelet is a small fragment of strange matter, small enough to be considered a particle. The size of an object composed of strange matter could, theoretically, range from a few femtometers across (with the mass of a light nucleus) to arbitrarily large. Once the size becomes macroscopic (on the order of meters across), such an object is usually called a ''strange star''. The term "strangelet" originates with Edward Farhi and Robert Jaffe in 1984. It has been theorized that strangelets can convert matter to strange matter on contact.<ref name = Farhi-Jaffe-1984>{{cite journal |last1=Farhi |first1=Edward |author1-link=Edward Farhi |last2=Jaffe |first2=R.L. |author2-link=Robert Jaffe (physicist) |year=1984 |title=Strange matter |journal=Physical Review D |volume=30 |issue=11 |pages=2379–2390 |bibcode=1984PhRvD..30.2379F |doi=10.1103/PhysRevD.30.2379 }}</ref> Strangelets have also been suggested as a dark matter candidate.<ref name=Witten-1984>{{cite journal |last1=Witten |first1=Edward |author1-link=Edward Witten |year=1984 |title=Cosmic separation of phases |journal=Physical Review D |volume=30 |issue=2 |pages=272–285 |bibcode=1984PhRvD..30..272W |doi=10.1103/PhysRevD.30.272 }}</ref>
== Theoretical possibility ==
=== Strange matter hypothesis === The known particles with strange quarks are unstable. Because the strange quark is heavier than the up and down quarks, it can spontaneously decay, via the weak interaction, into an up quark, an electron, and an antineutrino. Consequently, particles containing strange quarks, such as the lambda particle, always lose their strangeness, by decaying into lighter particles containing only up and down quarks.
However, condensed states with a larger number of quarks might not suffer from this instability. The possibility that some sufficiently dense clump of nuclear matter containing some strange quarks might be stable against decay is the ''"strange matter hypothesis"'', proposed separately by Arnold Bodmer in 1971<ref>{{cite journal |last=Bodmer |first=A.R. <!-- |author-link=Arnold Bodmer --> |date=1971-09-15 |df=dmy-all |title=Collapsed nuclei |journal=Physical Review D |volume=4 |issue=6 |pages=1601–1606 |doi=10.1103/PhysRevD.4.1601 |bibcode=1971PhRvD...4.1601B }}</ref> and by Edward Witten in 1984.<ref name=Witten-1984/> According to this hypothesis, when a large enough number of quarks are concentrated together, the lowest energy state is one which has roughly equal numbers of up, down, and strange quarks, namely a strangelet. This stability would occur because of the Pauli exclusion principle; having three types of quarks, rather than two as in normal nuclear matter, allows more quarks to be placed in lower energy levels, hence confined in a smaller space at the same pressure.
=== Relationship with nuclei === A ''nucleon'' is a nuclear particle (in some nuclei a fairly large number of them) each composed of a number of up and down quarks, confined into triplets (neutrons and protons). According to the strange matter hypothesis, strangelets are more stable than nuclei, so nuclei are expected to decay into strangelets. But this process may be extremely slow because there is a large energy barrier to overcome: as the weak interaction starts making a nucleus into a strangelet, the first few strange quarks form strange baryons, such as the Lambda, which are heavy. Only if many conversions occur almost simultaneously will the number of strange quarks reach the critical proportion required to achieve a lower energy state. This is very unlikely to happen, so even if the strange matter hypothesis were correct, nuclei would never be seen to decay to strangelets because their lifetime would be longer than the age of the universe.<ref name=saga>{{cite journal |last1=Norbeck |first1=E. |last2=Onel |first2=Y. |year=2011 |title=The strangelet saga|journal=Journal of Physics: Conference Series |volume=316 |issue=1 |article-number=012034–2 |doi=10.1088/1742-6596/316/1/012034 |doi-access=free |bibcode=2011JPhCS.316a2034N }}</ref>
=== Size === The stability of smaller strangelets (as opposed to strange stars) depends on their size, because of surface tension or charge screening.
* Strange matter's natural surface tension at the interface between quark matter and vacuum affects small strangelets more than big ones, but the actual surface tension natural to strange matter is unknown. If it is smaller than a critical value of a few MeV per square femtometer<ref name='screen'>{{cite journal |last1=Alford |first1=Mark G. |last2=Rajagopal |first2=Krishna |last3=Reddy |first3=Sanjay |last4=Steiner |first4=Andrew W. |year=2006 |title=Stability of strange star crusts and strangelets |journal=Physical Review D |volume=73 |issue=11 |article-number=114016 |doi=10.1103/PhysRevD.73.114016 |s2cid=35951483 |arxiv=hep-ph/0604134 |bibcode=2006PhRvD..73k4016A }}</ref> then larger-sized strangelets are unstable and will tend to fission into smaller strangelets; however strange stars would still be stabilized by gravity holding them together, and if fractured, compressing the parts back together. If the surface tension natural to strange matter is larger than the (unknown) critical value, then strangelets become more stable as they get larger / heavier.
* The effects of charge screening allows small strangelets to be charged, with a neutralizing cloud of electrons / positrons around them, but still requires larger strangelets – like any large piece of any kind of matter – to be electrically neutral in their interiors. The charge screening distance tends to be of the order of a few femtometers, so only the outer few femtometers of a strangelet can carry a charge.<ref>{{cite journal |last1=Heiselberg |first1=H. |year=1993 |title=Screening in quark droplets |journal=Physical Review D |volume=48 |issue=3 |pages=1418–1423 |bibcode=1993PhRvD..48.1418H |doi=10.1103/PhysRevD.48.1418 |pmid=10016374 }}</ref>
== Natural or artificial occurrence == Although nuclei do not decay to strangelets, there are other ways to create strangelets, so if the strange matter hypothesis is correct there should be strangelets in the universe. There are at least three ways they might be created in nature:
; Cosmological strangelets: In the very early universe, when the QCD confinement phase transition occurred, it is possible that strangelets were created along with the neutrons and protons that form ordinary matter. ; High-energy processes: The universe is full of very high-energy particles (cosmic rays). It is possible that when these collide with each other or with neutron stars they may provide enough energy to overcome the energy barrier and create strangelets from nuclear matter. Some identified exotic cosmic ray events, such as "Price's event" – ''i.e.,'' those with very low charge-to-mass ratios (as the ''s''-quark itself possesses charge commensurate with the more-familiar ''d''-quark, but is much more massive) – could have already registered strangelets.<ref>{{cite journal |last1=Banerjee |first1=Shibaji |last2=Ghosh |first2=Sanjay K. |last3=Raha |first3=Sibaji |last4=Syam |first4=Debapriyo |year=2000 |title=Can cosmic strangelets reach the Earth? |journal=Physical Review Letters |volume=85 |issue=7 |pages=1384–1387 |doi=10.1103/PhysRevLett.85.1384 |pmid=10970510 |s2cid=27542402 |arxiv=hep-ph/0006286 |bibcode=2000PhRvL..85.1384B }}</ref><ref>{{Cite journal |last1=Rybczynski |first1=M. |last2=Wlodarczyk |first2=Z. |last3=Wilk |first3=G. |year=2002 |title=Can cosmic rays provide sign of strangelets? |journal=Acta Physica Polonia B |volume=33 |issue=1 |pages=277–296 |arxiv=hep-ph/0109225 |bibcode=2002AcPPB..33..277R }}</ref>
; Cosmic ray impacts: In addition to head-on collisions of cosmic rays, ultra high energy cosmic rays impacting on Earth's atmosphere may create strangelets.
These scenarios offer possibilities for observing strangelets. If strangelets can be produced in high-energy collisions, then they might be produced by heavy-ion colliders. Similarly, if there are strangelets flying around the universe, then occasionally a strangelet should hit Earth, where it may appear as an exotic type of cosmic ray; alternatively, a stable strangelet could end up incorporated into the bulk of the Earth's matter, acquiring an electron shell proportional to its charge and hence appearing as an anomalously heavy isotope of the appropriate element – though searches for such anomalous "isotopes" have, so far, been unsuccessful.<ref>{{cite journal |last1=Lu |first1=Z.-T. |last2=Holt |first2=R.J. |last3=Mueller |first3=P. |last4=O'Connor |first4=T.P. |last5=Schiffer |first5=J. P. |last6=Wang |first6=L.-B. |date=May 2005 |title=Searches for stable strangelets in ordinary matter: Overview and a recent example |journal=Nuclear Physics A |volume=754 |pages=361–368 |doi=10.1016/j.nuclphysa.2005.01.038 |arxiv=nucl-ex/0402015 |bibcode=2005NuPhA.754..361L }}</ref>
=== Accelerator production === At heavy ion accelerators like the Relativistic Heavy Ion Collider (RHIC), nuclei are collided at relativistic speeds, creating strange and antistrange quarks that could conceivably lead to strangelet production. The experimental signature of a strangelet would be its very high ratio of mass to charge, which would cause its trajectory in a magnetic field to be very nearly, but not quite, straight. The STAR collaboration has searched for strangelets produced at the RHIC,<ref>{{cite journal |last1= Abelev |first1= B.I. |last2= Aggarwal |first2= M.M. |last3= Ahammed |first3= Z. |last4= Anderson |first4= B.D. |last5= Arkhipkin |first5= D. |last6= Averichev |first6= G.S. |last7= Bai |first7= Y. |last8= Balewski |first8= J. |last9= Barannikova |first9= O. |last10= Barnby |first10= L.S. |last11= Baudot |first11= J. |last12= Baumgart |first12= S.|last13= Belaga |first13= V.V. |last14= Bellingeri-Laurikainen |first14= A. |last15= Bellwied |first15= R. |last16= Benedosso|first16= F. |last17= Betts |first17= R.R. |last18= Bhardwaj |first18= S. |last19= Bhasin |first19= A. |last20= Bhati |first20= A.K. |last21= Bichsel |first21= H. |last22=Bielcik |first22= J. |last23= Bielcikova |first23= J. |last24= Bland |first24= L.C. |last25= Blyth |first25=S.-L. |last26= Bombara |first26= M. |last27= Bonner |first27= B.E. |last28= Botje |first28= M. |last29= Bouchet |first29= J. |last30= Brandin |first30= A.V. |display-authors=6 |year= 2007 |title= Strangelet search in Au+Au collisions at {{nobr|{{mvar|s}}<sub>NN</sub> {{=}} 200 GeV}} |journal= Physical Review C|volume= 76 |issue= 1 |article-number= 011901 |arxiv= nucl-ex/0511047 |bibcode= 2007PhRvC..76a1901A |doi= 10.1103/PhysRevC.76.011901|s2cid= 119498771}}</ref> but none were found. The Large Hadron Collider (LHC) is even less likely to produce strangelets,<ref name="LSAGreport">{{cite journal |last1=Ellis |first1=John |last2=Giudice |first2=Gian |last3=Mangano |first3=Michelangelo |last4=Tkachev |first4=Igor |last5=Wiedemann |first5=Urs |collaboration=LHC Safety Assessment Group |year=2008 |title=Review of the safety of LHC collisions |journal=Journal of Physics G: Nuclear and Particle Physics |volume=35 |issue=11 |at=115004 (18pp) |doi=10.1088/0954-3899/35/11/115004 |arxiv=0806.3414 |s2cid=53370175 |bibcode=2008JPhG...35k5004E |url=http://cdsweb.cern.ch/record/1111112?ln=fr |via=CERN record |archive-url=https://web.archive.org/web/20180928123118/http://cdsweb.cern.ch/record/1111112?ln=fr |archive-date=2018-09-28 }}</ref> but searches are planned<ref>{{cite journal |last1=Sadovsky |first1=S.A. |last2=Kharlov |first2=Yu.V. |last3=Angelis |first3=A.L.S. |last4=Gładysz-Dziaduš |first4=E. |last5=Korotkikh |first5=V.L. |last6=Mavromanolakis |first6=G. |last7=Panagiotou |first7=A.D. |year=2004 |title=Model for describing the production of Centauro events and strangelets in heavy-ion collisions |journal=Physics of Atomic Nuclei |volume=67 |issue=2 |pages=396–405 |doi=10.1134/1.1648929|s2cid=117706766 |arxiv=nucl-th/0301003 |bibcode=2004PAN....67..396S }}</ref> for the LHC ALICE detector.
=== Space-based detection === The Alpha Magnetic Spectrometer (AMS), an instrument that is mounted on the International Space Station, could detect strangelets.<ref>{{cite journal |last1=Sandweiss |first1=J. |year=2004 |title=Overview of strangelet searches and Alpha Magnetic Spectrometer: When will we stop searching? |journal=Journal of Physics G: Nuclear and Particle Physics |volume=30 |issue=1 |pages=S51–S59 |bibcode=2004JPhG...30S..51S |doi=10.1088/0954-3899/30/1/004 }}</ref>
=== Possible seismic detection === In May 2002, a group of researchers at Southern Methodist University reported the possibility that strangelets may have been responsible for seismic events recorded on 22 October and 24 November 1993.<ref>{{cite journal|last1=Anderson |first1=D.P. |last2=Rajagopal |first2=Krishna |last3=Reddy |first3=Sanjay |last4=Steiner |first4=Andrew |year=2003 |title=Unexplained sets of seismographic station reports and a set consistent with a quark nugget passage |journal=The Bulletin of the Seismological Society of America |volume=93 |issue=6 |pages=2363–2374 |arxiv=astro-ph/0205089 |bibcode=2003BuSSA..93.2363A |doi=10.1785/0120020138 |s2cid=43388747 }}</ref> The authors later retracted their claim, after finding that the clock of one of the seismic stations had a large error during the relevant period.<ref>{{cite journal |last1=Herrin |first1=Eugene T. |last2=Rosenbaum |first2=Doris C. |last3=Teplitz |first3=Vigdor L. |last4=Steiner |first4=Andrew |year=2006 |title=Seismic search for strange quark nuggets |journal=Physical Review D |volume=73 |issue=4 |article-number=043511 |doi=10.1103/PhysRevD.73.043511 |s2cid=119368573 |arxiv=astro-ph/0505584 |bibcode=2006PhRvD..73d3511H }}</ref>
It has been suggested that the International Monitoring System be set up to verify the Comprehensive Nuclear Test Ban Treaty (CTBT) after entry into force may be useful as a sort of "strangelet observatory" using the entire Earth as its detector. The IMS will be designed to detect anomalous seismic disturbances down to {{convert|1|ktonTNT|lk=on}} energy release or less, and could be able to track strangelets passing through Earth in real time if properly exploited.
=== Impacts on Solar System bodies === It has been suggested that strangelets of subplanetary (i.e. heavy meteorite) mass would puncture planets and other Solar System objects, leading to impact craters which show characteristic features.<ref>{{cite journal |last1=Rafelski |first1=Johann |last2=Labun |first2=Lance |last3=Birrell |first3=Jeremiah |last4=Steiner |first4=Andrew |year=2013 |title=Compact ultra-dense matter impactors |journal=Physical Review Letters |volume=110 |issue=11 |article-number=111102 |doi=10.1103/PhysRevLett.110.111102|pmid=25166521|s2cid=28532909 |arxiv=1104.4572 |bibcode=2011arXiv1104.4572R |url=http://inspirehep.net/record/897105 |url-status=live |access-date=2011-11-13 |archive-url=https://web.archive.org/web/20220322135859/https://inspirehep.net/literature/897105 |archive-date=2022-03-22 }}</ref>
== Potential propagation == {{See also|Safety of high-energy particle collision experiments}} If the strange matter hypothesis is correct, and if a stable negatively-charged strangelet with a surface tension larger than the aforementioned critical value exists, then a larger strangelet would be more stable than a smaller one. One speculation that has resulted from the idea is that a strangelet coming into contact with a lump of ordinary matter could over time convert the ordinary matter to strange matter.<ref name=DDH/><ref name=BJSW/><!-- original suggestion may have been Glashow and De Rujula in Nature-->
This is not a concern for strangelets in cosmic rays because they are produced far from Earth and have had time to decay to their ground state, which is predicted by most models to be positively charged, so they are electrostatically repelled by nuclei, and would rarely merge with them.<ref>{{cite journal |last1=Madsen |first1=Jes|year=2000 |title=Intermediate mass strangelets are positively charged |journal=Physical Review Letters |volume=85 |issue=22 |pages=4687–4690 |doi=10.1103/PhysRevLett.85.4687 |pmid=11082627 |s2cid=44845761 |arxiv=hep-ph/0008217|bibcode=2000PhRvL..85.4687M }}</ref><ref>{{cite arXiv|eprint=astro-ph/0612784|title=Strangelets in Cosmic Rays|last1=Madsen|first1=Jes|year=2006 }}</ref> On the other hand, high-energy collisions could produce negatively charged strangelet states, which could live long enough to interact with the nuclei of ordinary matter.<ref>{{cite journal |last1=Schaffner-Bielich |first1=Jürgen |last2=Greiner |first2=Carsten |last3=Diener |first3=Alexander |last4=Stöcker |first4=Horst |year=1997 |title=Detectability of strange matter in heavy ion experiments |journal=Physical Review C |volume=55 |issue=6 |pages=3038–3046 |doi=10.1103/PhysRevC.55.3038 |s2cid=12781374 |arxiv=nucl-th/9611052 |bibcode=1997PhRvC..55.3038S }}</ref>
The danger of catalyzed conversion by strangelets produced in heavy-ion colliders has received some media attention,<ref>{{cite magazine |first=Robert |last=Matthews |date=28 August 1999 |magazine=New Scientist |title=A black hole ate my planet |url=https://www.newscientist.com/article/mg16322014-700-a-black-hole-ate-my-planet/ |url-status=live |access-date=25 April 2019 |archive-url=https://web.archive.org/web/20190322083449/https://www.newscientist.com/article/mg16322014-700-a-black-hole-ate-my-planet |archive-date=22 March 2019 }} <!-- ORIGINALLY: http://www.kressworks.com/Science/A_black_hole_ate_my_planet.htm --></ref><ref>''Horizon: End Days'', an episode of the BBC television series ''Horizon''</ref> and concerns of this type were raised<ref name='DDH'>{{cite journal |last1=Dar |first1=A. |last2=de Rujula |first2=A. |last3=Heinz |first3=Ulrich |last4=Steiner |first4=Andrew |year=1999 |title=Will relativistic heavy-ion colliders destroy our planet? |journal=Physics Letters B |volume=470 |issue=1–4 |pages=142–148 |arxiv=hep-ph/9910471 |bibcode=1999PhLB..470..142D |doi=10.1016/S0370-2693(99)01307-6 |s2cid=17837332 }}</ref><ref>{{cite magazine |last1=Wagner |first1=Walter L. |year=1999 |title=Black holes at Brookhaven? |magazine=Scientific American |volume=281 |issue=1 |page=8 |jstor=26058304 }}</ref> at the commencement of the RHIC experiment at Brookhaven, which could potentially have created strangelets. A detailed analysis<ref name='BJSW'>{{cite journal |last1=Jaffe |first1=R.L. |last2=Busza |first2=W. |last3=Wilczek |first3=F. |last4=Sandweiss |first4=J. |year=2000 |title=Review of speculative ''disaster scenarios'' at RHIC |journal=Reviews of Modern Physics |volume=72 |issue=4 |pages=1125–1140 |doi=10.1103/RevModPhys.72.1125 |s2cid=444580 |arxiv=hep-ph/9910333 |bibcode=2000RvMP...72.1125J }}</ref> concluded that the RHIC collisions were comparable to ones which naturally occur as cosmic rays traverse the Solar System, and thus such a disaster would have already occurred were it possible. RHIC has been operating since 2000 without incident. Similar concerns have been raised about the operation of the LHC at CERN<ref name=NYT>{{cite news |first=D. |last=Overbye |author-link=Dennis Overbye |date=29 March 2008 |title=Asking a judge to save the world, and maybe a whole lot more |newspaper=The New York Times |url=https://www.nytimes.com/2008/03/29/science/29collider.html?ref=us |url-status=live |access-date=23 February 2017 |archive-url=https://web.archive.org/web/20171228112253/http://www.nytimes.com/2008/03/29/science/29collider.html?ref=us |archive-date=28 December 2017 }}</ref> but such fears are dismissed as far-fetched by scientists.<ref name=NYT/><ref>{{cite press release |title=Safety at the LHC |department=Large Hadron Collider |publisher=CERN |url=http://public.web.cern.ch/Public/en/LHC/Safety-en.html |url-status=live |access-date=2008-06-11 |archive-url=https://web.archive.org/web/20080513222235/http://public.web.cern.ch/PUBLIC/en/LHC/Safety-en.html |archive-date=2008-05-13 }}</ref><ref>{{cite report |first1=J. |last1=Blaizot |display-authors=etal |year=2003 |title=Study of Potentially Dangerous Events During Heavy-Ion Collisions at the LHC |type=CERN library record |publisher=CERN |url=http://cdsweb.cern.ch/search?sysno=002372601cer |via=cdsweb.cern.ch |archive-url=https://web.archive.org/web/20190402072042/http://cdsweb.cern.ch/search?sysno=002372601cer |archive-date=2019-04-02 |df=dmy-all }} : Alternate source: {{cite report |last1=Blaizot |display-authors=etal |year=2003 |title=Study of Potentially Dangerous Events During Heavy-Ion Collisions at the LHC |series=CERN Yellow Reports Server |url=http://doc.cern.ch/yellowrep/2003/2003-001/p1.pdf |via=doc.cern.ch |archive-url=https://web.archive.org/web/20080907004852/http://doc.cern.ch/yellowrep/2003/2003-001/p1.pdf |archive-date=2008-09-07 |df=dmy-all }}</ref>
In the case of a neutron star, the conversion scenario may be more plausible. A neutron star is in a sense a giant nucleus (20 km across), held together by gravity, but it is electrically neutral and would not electrostatically repel strangelets. If a strangelet hit a neutron star, it might catalyze quarks near its surface to form into more strange matter, potentially continuing until the entire star became a strange star.<ref>{{cite journal |last1=Alcock |first1=Charles |last2=Farhi |first2=Edward |last3=Olinto |first3=Angela |year=1986 |title=Strange stars |journal=Astrophysical Journal |volume=310 |page=261 |doi=10.1086/164679 |bibcode = 1986ApJ...310..261A }}</ref>
== Debate about the strange matter hypothesis == The strange matter hypothesis remains unproven. No direct search for strangelets in cosmic rays or particle accelerators has yet confirmed a strangelet. If any of the objects such as neutron stars could be shown to have a surface made of strange matter, this would indicate that strange matter is stable at zero pressure, which would vindicate the strange matter hypothesis. However, there is no strong evidence for strange matter surfaces on neutron stars.
Another argument against the hypothesis is that if it were true, essentially all neutron stars should be made of strange matter, and otherwise none should be.<ref>{{cite journal |last1=Caldwell |first1=R.R. |last2=Friedman |first2=John L. |year=1991 |title=Evidence against a strange ground state for baryons |journal=Physics Letters B |volume=264 |issue=1–2 |pages=143–148 |doi=10.1016/0370-2693(91)90718-6 |bibcode=1991PhLB..264..143C }}</ref> Even if there were only a few strange stars initially, violent events such as collisions would soon create many fragments of strange matter flying around the universe. Because collision with a single strangelet would convert a neutron star to strange matter, all but a few of the most recently formed neutron stars should by now have already been converted to strange matter.
This argument is still debated,<ref>{{cite journal |last1=Madsen |first1=Jes |last2=Larsen|first2=Jonas |year=2003 |title=Strangelets as Cosmic Rays beyond the Greisen-Zatsepin-Kuzmin Cutoff |journal=Physical Review Letters |volume=90 |issue=12 |article-number=121102 |doi=10.1103/PhysRevLett.90.121102 |pmid=12688863 |bibcode=2003PhRvL..90l1102M|s2cid=118913495 |arxiv=astro-ph/0211597 }}</ref><ref>{{cite journal |last1=Balberg |first1=Shmuel |year=2004 |title=Comment on ''Strangelets as cosmic rays beyond the Greisen-Zatsepin-Kuzmin cutoff'' |journal=Physical Review Letters |volume=92 |issue=11 |article-number=119001 |doi=10.1103/PhysRevLett.92.119001 |pmid=15089181 |arxiv=astro-ph/0403503 |bibcode=2004PhRvL..92k9001B |s2cid=35971928 }}</ref><ref>{{cite journal |last1=Madsen |first1=Jes |year=2004 |title=Madsen Replies |journal=Physical Review Letters |volume=92 |issue=11 |article-number=119002 |bibcode=2004PhRvL..92k9002M |s2cid=26518446 |arxiv=astro-ph/0403515 |doi=10.1103/PhysRevLett.92.119002 }}</ref><ref>{{cite journal |last1=Madsen |first1=Jes |year=2005 |title=Strangelet propagation and cosmic ray flux |journal=Physical Review D |volume=71 |issue=1 |article-number=014026 |doi=10.1103/PhysRevD.71.014026 |s2cid=119485839 |arxiv=astro-ph/0411538 |bibcode=2005PhRvD..71a4026M }}</ref> but if it is correct then showing that one old neutron star has a conventional nuclear matter crust would disprove the strange matter hypothesis.
Because of its importance for the strange matter hypothesis, there is an ongoing effort to determine whether the surfaces of neutron stars are made of strange matter or nuclear matter. The evidence currently favors nuclear matter. This comes from the phenomenology of X-ray bursts, which is well explained in terms of a nuclear matter crust,<ref>{{cite journal |last1=Heger |first1=Alexander |last2=Cumming |first2=Andrew |last3=Galloway |first3=Duncan K.|last4=Woosley |first4=Stanford E. |year=2007 |title=Models of type I X-ray bursts from GS 1826-24: A probe of rp-process hydrogen burning |journal=The Astrophysical Journal |volume=671 |issue=2 |page=L141 |arxiv=0711.1195 |bibcode=2007ApJ...671L.141H |doi=10.1086/525522 |s2cid=14986572 }}</ref> and from measurement of seismic vibrations in magnetars.<ref>{{cite journal |last1=Watts |first1=Anna L. |last2=Reddy |first2=Sanjay |year=2007 |title=Magnetar oscillations pose challenges for strange stars |journal=Monthly Notices of the Royal Astronomical Society |volume=379 |issue=1 |pages=L63 |doi=10.1111/j.1745-3933.2007.00336.x |doi-access=free |arxiv=astro-ph/0609364 |bibcode=2007MNRAS.379L..63W |s2cid=14055493 }}</ref>
== In fiction == * One episode of the TV series ''Odyssey 5'' featured an attempt to destroy the planet by intentionally creating negatively charged strangelets in a particle accelerator.<ref>{{cite episode |first=Manny |last=Coto |year=2002 |title=Trouble with Harry |series=Odyssey 5 |url=https://www.imdb.com/title/tt0664394/ |via=IMDB |archive-url=https://web.archive.org/web/20190930015717/https://www.imdb.com/title/tt0664394/ |archive-date=2019-09-30 }} — an episode of the Canadian science fiction television series ''Odyssey 5''.</ref> * The BBC docudrama ''End Day'' features a scenario where a particle accelerator in New York City explodes. This creates a strangelet which creates a chain reaction which destroys Earth. * The Robert L. Forward story "A Matter Most Strange" included ins collection ''Indistinguishable from Magic'' deals with the making of a strangelet in a particle accelerator. * In Douglas Preston's 2010 novel ''Impact'', an alien machine creates strangelets. The machine's strangelets impact the Earth and Moon and pass through them. * Steve Alten's 2011 novel ''Phobos'', written as the third and final part of his ''Domain'' trilogy, presents a fictional story where strangelets are unintentionally created at the LHC and escape from it to destroy the Earth. * In Donald E. Westlake's 1992 black-comedy novel ''Humans'', an irritated God sends an angel to Earth to bring about Armageddon by means of using a strangelet created in a particle accelerator to convert the Earth into a quark star. * In the 2010 film ''Quantum Apocalypse'', a strangelet approaches the Earth from space. * In Hannu Rajaniemi's novel ''The Quantum Thief'' (and the rest of the author's ''Jean le Flambeur'' trilogy) strangelets are mostly used as weapons, but during an early project to terraform Mars, one was used to convert Phobos into an auxiliary "sun".
== See also == * Grey goo * Ice-nine * Hyperon
== Further reading == {{refbegin|25em|small=yes}} * {{cite web |last=Holden |first=Joshua |date=17 May 1998 |title=The story of strangelets |department=Department of Physics and Astronomy |type=academic webpage |publisher=Rutgers University |place=New Brunswick–Piscataway, NJ |url=http://www.physics.rutgers.edu/~jholden/strange/strange.html |access-date=2010-04-01 |archive-url=https://web.archive.org/web/20100107024303/http://www.physics.rutgers.edu/~jholden/strange/strange.html |archive-date=7 January 2010 |df=dmy-all}} * {{cite journal |first=Fridolin |last=Weber |year=2005 |title=Strange quark matter and compact stars |journal=Progress in Particle and Nuclear Physics |volume=54 |issue=1 |pages=193–288 |doi=10.1016/j.ppnp.2004.07.001 |arxiv=astro-ph/0407155 |bibcode = 2005PrPNP..54..193W |s2cid=15002134}} * {{cite book |first=Jes |last=Madsen |year=1999 |chapter=Physics and astrophysics of strange quark matter |title=Hadrons in Dense Matter and Hadrosynthesis |series=Lecture Notes in Physics |volume=516 |pages=162–203 |doi=10.1007/BFb0107314 |arxiv=astro-ph/9809032 |s2cid=16566509 |isbn=978-3-540-65209-0 }} {{refend}}
== References == {{reflist|25em}}
== External links == * {{cite AV media |title=The Most Dangerous Stuff in the Universe – Strange Stars Explained |date=14 April 2019 |series=Kurzgesagt |medium=video |url=https://www.youtube.com/watch?v=p_8yK2kmxoo |url-status=live |via=YouTube |access-date=15 April 2019 |archive-url=https://ghostarchive.org/varchive/youtube/20211215/p_8yK2kmxoo |archive-date=2021-12-15 |df=dmy-all }} {{Global catastrophic risks}} {{Stellar core collapse}}
Category:Concepts in astrophysics Category:Celestial mechanics Category:Doomsday scenarios Category:Exotic matter Category:History of astronomy Category:History of physics Category:Hypothetical composite particles Category:Hypotheses in physics Category:Nuclear physics Category:Quantum chromodynamics Category:Quantum mechanics Category:Quark matter Category:Strange quark Category:Unsolved problems in astronomy Category:Unsolved problems in physics