r 2000/08/10 CIA-RDP96-00-W-.RO00100030001-9 r,stablisl-zed 184"') AM-ERICAANFebruary 1970 Volunic 222 Number 2 ARTICLES 13 THE ASSESSMENT OF TECHNOLOGY, by Ilarvey Brooks and Rayniond Bowers How can technology be fostered while avoiding undesirable effects? g 22 LARGE-SCALE INTEGRATION IN ELECTRONICS, by F. G. Heath Thousands 6f circuit elements can I-low be simultaneously made on a single "chip." 32 THE AFAR TRIANGLE, by Haronn Ttz;eff A fantastic landscape beside the Red Sea appears to be an ocean in the making. 52 THE PHYSIOLOGY OF HIGH ALTITUDE, by Raymond J. Ilock How do men and other animals adapt to permanent residence above 6,000 feet? 68 PARTICLES THAT GO FASTER TIIAN LIGHT, by Gerald Feifiberg They have not been discovered, but there are reasons to believe they may exist. 82 PHOSI)IIENES, by Gerald Oster The patterns we see when we close our eyes are clues to how tbe eye works. -88 THE RANGELANDS OF THE WESTERN U.S., by R. Alerton Love -iumane uses. These vast tracts normally reserved for grazing can have other I 98 CELL SURGERY BY LASER, by Michael W. Berns and Donald E'. Rourids A tiny, intense spot of light is used to probe the physiology of the living cell. C, DEPARTIMENTS 6 LETTERS 9 50 AND 100 YEARS AGO 10 THE AUTHORS 42 SCIENCE AND THE CITIZEN 112 MATHEMATICAL CAMES 116 THE AMATEUR SCIENTIST 122 BOOKS 126 BIBLIOGRAPHY NOARD OF EDITORS Gerard Piel (Publisher), Dennis Flanagan (Editor), Francis Bello (Associate Editor), Philip Morrison (Book Editor), Jonathan B. Piel, Jolin Pureell, James T. Rogers, Armand Sch-A-ab, Jr., C. L. Stong, Joseph Wisnovsky ART DEPARTMENI Jerome Snyder (Art Director). Samuel L. I loward (Associate Art Director) VR009CTEOR DEPARTMEKT Richard Sasso (Production Manager), Arnold P. Shindlcr and Doreen Tra~er (Assistant Production Managers), Pauline Ray COPY DIEPARIMENT Sally Porter Jenks (Copy Chief), Sally S. Fields, Dorothy Patterson, Julio E. Xavier GENERAL MANAGER Donald 11. Miller, Jr. ADVERItSINO MANAGER Allan Wittman ASSISTANT TO VHE PUBLISHER Steplien.M. Fisclier 47RU04 00030001-9 ~~Df'916 007 A D AL fAAILING OFFICES. AUTHORIZED AS 5~.- OND-CLAS$ MAIL BY 1HE PC,51 OFFICE OLPARImENT, OTTAWA, CANADA, AND fCR PATMEN7 OF PDSTAGE IN CASH. SUMCK!1`110n f.~'E:$WeER YE". r n-T 4-1 r-JaW ",r0RoLi;Zf1JJWC2kWA"/1k"ti~f b6t4ftW0ajg 40J-9 ,Yorts to d etect such particles, nained tachyQns, have yielded 0711)- 71 e o 11, ItS. CO 7 belief. howem- their *atice res Itral)`[O C0111711071. existence (vould not be hIC0718i8te7lt with the theory of relaticity by Gerald Feinberg V vice the forinulation of the special theory of relativity by Einstein in 1905 arid its subsequent verifica- tion by innumerable experiments, physi- cists have cenerally believed that the speed of light in a vacuum (about 300,- 000 kilometers per second) is the i-naxi- nium speed at which energy or informa- tion call travel through space. Indeed, Einstein's first article oil relativity con- tains the statement that "velocities great- er than that of light... have no possibil- ity of existence." The basis of Einstein's conclusion was his discovery that the equations of rela- tivit y implied that the -mass of an object hicreases as its speed increases, becom- ina infinite at the speed of light (which is usually denoted c). Since the mass of a body measures its resistance to a Change of speed, when the mass be- Comes Infinite the body cannot be made to go any faster. Stated somewhat differ- ently, the relation between energy and speed implied by relativity is such that as the speed of z body approaches c its energy becomes infinite. Since this ener- gy must be supplied by whatever is ac- celeratinc, the body, an infinite source of ellergy would be needed to speed up a A' body to the speed of light from any low- er speed. No such infinite energy source is available, and so it is impossible to make a body go from less than c to c. Furtherniore, if a body could some- how be made to go from a speed less than c to one areater than c, the same relativity equations imply that its energy and momentum would becorne iniagi- nary numbers, that is, numbers contain- ing a square root of a negative number. This situation does not sceyn to have any physical meaning. Objects with imagi- nary energy clearly cannot exchange energy with objects having real energy and hence cannot affect them. Accord- ingly, such objects could not be detected by real instruments, and can be said not to exist. Within the context in which Einstein worked, -,%,here the properties of objects varied continuously avid where the creation of new objects was not con- sidered, it therefore seemed a logical conclusion that no form of energy, and hence no matter, could travel faster than light. With the development of subatom- ic physics, bovvever, the context has changed considerably. We Dow know that the subatomic particles can easily be created or destroyed, and that in their mutual interactions their energies avid other properties change discontinuously, rather than in the smooth way envi- sioned in classical physics. Therefore one can imagine the creation of particles al- ready traveling faster than light, and so avoid the need for accelerating them through the "light barrier" with the at- tendant expenditure of infinite energy. In addition, one can consistently re- quire that such particles always travel at speeds greater than c, xvIiich obviously cannot be the case for known particles. If one assumes these conditions, there is no probleni in satisfying the require- nlent that the particles carry real en- ergy arid momentum. This can be done mathematically by allowing a certain constant that appears in the relation be- tween energy and speed to bean imacri- nary number, rather than a real number as it is for ordinary particles [see top il- lustration on next two pages]. This con- stant is usually known as the Test Mass, because for ordinary objects, which can be slowed to rest, it gives the value of the object's mass when at rest. For the hypothetical faster-than-light particles, which can never be brought to SEARCH FOR TACIIYONS led the author and his colleagues at Columbia University to scrutinize thousands of bubble-chamber photographs such as the one oil the opposite page for indirect evidence of live occurrence of neutral tachyons among the by-products of cer. tain subatomic interactions. The photographs, i%bich ivere originally made at the Brook- haven National Laboratory for another experiment, ivere analyzed by means of the in,- miss" method. In this approach the energy and momentum of tile charged particles in the reaction are nieat~urcd directly from the configuration of the tracks they make in the bubble chamber. Although neutral particles are usually not observed directly, it is possible to tell from the values weaured for the charged particles whether or not any neutral par. ticles have been produced, an(] also what the missing mass of these, particles is. In this caEe a negative K rueson (K-) was allowed to come to rest and be captured by a proton in the hydrogen bubble chamber (see diagram at left). One neutral pactiele, a lanilvda hyperon (All), was produced and %%aS detected through its decay into two charged particlct~, a Ilega- live pion (-,, -') and a proton f 1) + ). In order to conserve energy and momentum, another neutral particle (xu) had to be produced in this reaction, but the experimenters were able f E- MC2 b (V21C2) X_ =-- /7~C2 E, EQUATIONS OF RELATIVITY pertinent to a discussion of the possible existence of tachyons are shown on these two pages. The relation between energy and speed that must be sat6fied by any object obeying the special theory of relativity is given by equation a, -where E is the energy of the object, v is its speed and c is the speed of light. The quantity nt is known as the rest mass of the ob. ject and is related to the energy E0 that the object has at rest by equation b. For a body traveling faster than light v-'/c2 is greater rest, this constant is not directly measur- able, and there is no need for it to be real. The square of the rest mass, how- ever, can be expressed in terms of the measurable energy and momentum of an object and hence can be directly mea- sured. For ordinary objects the rest mass squared is found to be a positive real number. For faster-than-light particles it would be a negative number; indeed, this fact is the basis of one attempt to de- tect such particles. It should be men- tioned that there is a third class of parti- cles, including photons (lig glit quanta) and neutrinos, for which the rest mass is zero and %vhic~h always travel at c. The possibility therefore seems to exist that there is a new kind of natural object: one that always travels faster than light. The latter statement is in- variant, in the sense that if a body trav- els faster than light with respect to one observer, it will do so with respect to any other observer himself traveling in rela- tion to the first at less tban the speed of light. These are the only observers of which we have. -my knowledge, It must be stressed that all the. considerations given here and below are consistent with the special theory of relativity, and -its- sume the validity of its equations for de- scribing particles, even if the particles travel faster than light. n anticipation of the possible discover y of faster-thati-light particles, I named 0 them tachyons, from the Greck word tachys, meaning swift. In order to show how pbysicists have gone about search- in,- for tachyons, I sliall describe some of the, properties that would distinguish them from ordinary particles. One such property follows directly from the relation between crien, and Z:ly speed given in the equations of relativ ity. We have seen that for ordinary par ticles, as their speed increases, their en -t e, ~pprcwed,_Fwr Re*ap.a,20D01Qat1,0a; C 9 c2 E P VV /(~ ~) - than one; consequently the quantity under the square-root sign in equation a is negative, and the denoininator of the quantity that is equal to E in the saine equation is an imaginary number (that i~. -, number containing a square root of a negative number). In order to make E a real number one must choose in to be an iniagginary number, say nt As long as the object alisays travels at more than the speed of light, its energy, N, hirli can be written in the form shown in equation c, will then be real, because (,V2/C2) - 1 trast, an increase in speed results in a decrease in energy. Hence a tacliyon that was losing energy by interacting with matter oi- by radiating light would speed up, whereas a tachyon that was gaining energ from some outside source Cly would slow down, and its speed .vould approach c from above rather than be- low. Thus c acts as a linaiting speed for tachyons also, but the limit is a lower limit, rather than the upper limit that it is for ordhirary objects. In the limiting case' of a tacliyon rnov- ing at infinite speed its total energy would be zero, although its momentum would remain finite. It should be cmplia- sized that for a tacliyon at infinite speed it is the total energy that is zero and not just the kinetic energy. For an ordinary particle with nonzero rest mass the total energy can never vanish. The condition of infinite speed is, however, not invariant but depends on the observer. If a tachyon were moving at infinite speed as seen by one observer, its speed as measui -ed by another ob- server in motion with respect to the first would not be infinite but rather some finite value between c and infinity. This is another way of phrasing Einstein's discovery that simultaneity for events at different points in space has only a rela- tive and not an absolute nicaninu. n, secot -ict property ot taciiyons ttiat substantiall distinguishes thein from or y diiiary particles comes about from the way measurements of encru and time y change with the relative motion of ob servers. For oidinary particles the ener cry is a number whose value will cliancre from observer to observer but that will always be positive. A ticliyon whose C11 ergy is positive for one observer, hmv ever, iniclit appear to be liegative to oth o 11 Cl. Observers in niotion with respect to the first. This can occur for tacliyons be- Cause Of die c( at' f relativity that Q AC1JR-106ROMA97,A7 Pp 0, 1 ways less than its momentum naultipliecl by c; this ambivalence does not apply to ordinary particles. if ne gative- energy 0 tach),ons were emitted by the unexcited atoms of ordinary matter, this would cause the emitting atorns to be unstable, and hence the existence of such tachyons would contradict the Icnown. stability Of ordinary matter. he cliann in the sign of the criergy Tof a tachyon from observer to ob server is. connected to another peculiar property of,taclivons. If an ol-,IinarN par ticle is seen by one observer to be cinit ted (say by in atom A) at one tinie and absorbed elsewhere (by atom 13) at a later tirne, then any otlier observer ill relative motion will see this process in the sarne way-as emission by atorn A followed at a later time by absorption by atom B-although the time interval vifll vary frorn observer to observer. Tachy ons, ho-wever, because they would travel faster than light, vvould move between points in "space time- vvbose tinic-order I ing can vary from observer to observer. 0 Therefore if one observer saw a tachyon emitted by atorn A at one time t, and absorbed by atom B at a later ti-ne t., another observer could Grid fliat the ' fine ii t,' that he measures corresponding to ti is later than the tiFne W that lie nic,'AsUres corresponding to t- It this ocours, tne latter observer .vould natuxally want to interpret what happens in the follov.-ing way: The taclivon is emitted by atom P? at the carlier time t,,' and absorbed by atoiiiek at the later time t1'. It can be seen that this interchange of emission and absorption ab:o renloves tli6 problein of negative-energ , t~~chy ons, since the reversal betwoen observers of the si<,n of the energ OCCUIS if and 0 1-y only if the reversal in tinic-ordering Oc- D curs. Since (lie emission of a negative.- cilgry UlMl$ the absorption of a, 0 pIA61 ' Al Appf,"9d For 2f,,2) (VIL. will in this case be a positive quantity. The momentum p of any body obeying the special theory of relativity call be expressed in terms of its speed by meanb of equation (1, in which in is indepen- dent of v. It follows from a combination of this equation and equa. Lion a that tile quantity represented by equation e does not depend on v anti hence is the same for all observers. Tile quantity in2 (called the rest mass squared) is tben a constant for each object, even for bodies suclias photons klight quanta) or tachyons, wbich opposite direction produce the &ime ef- fect on the energy of a system, it is a]- ways possible for any observer to insist that all tach~-ons have positive energy, and that emission and absorption take place in the familiar time-ordering, thus removing the instability problems that negative-energy taclivons).vould present. This interpretation of the negative-ener- gy states of the tachyon Nvas first pro- posed in 1962 by 0. M. P. Bilaniuk, E. C. G. Sudarshan and ~7. K. Deshpande of the University of Rochester, Tile description giN-en above is in agreement ivith the principle of r ,clativ- ity requiring that tiny process that can be seen by one observer must also be a ATOM A ATOM B TIME 0 to 0 0 ti > t2 (3 PECULIAR PROPERTY OF TACIIYONS ar6cs from the fact that the tinic-ordering of points in "space time" between which a faster -than-light particle would move could vary front observer to observer. Titus a process that appears to one observer as emission of a tachyan by one atom folloN%ed by absorption of the lachyon b y another atom could be reversed for another obbervcr DIOVin~, ith NV respect to tile first. Ju. this schematic representation of such a phenomenon the first observer (1--ft) sees atom A at rest in its ground itate and atom B at rett in an excited state at tinic to. At ti atom B emits a taebyon (color), dropping to its ground state and leetat 2000/08/10 CIA-RDF 9 4078ZR 0101110P001-9 2 P E PV m2c4 c are never at rest. One can also deduce front ibe~e relations equation 11 X%bich implies that if v/C is less than one (as it is for ordinary objects), then pcIE is less than one, E2 _ p2C2 is greater than zero and hence 7~12 is positive. Oil the other hand, for objects that go fater than firlit v1c is greater than one, E2 - p2C2 is less than zero and hence n12 is negative. In either case the rest DlaSS SqU.1rCd should always have the same value for a given object and can be measured by nicasuring the energy and momentum for the object. possible process for my other observer. The principle does not require, however, that different observers a,,rce oil the in- terpretation. of any, indiVidual process. Hence there is no contradiction of the principle of relativity involved in the fact that one observer views as absorp- tion what another views as emission, since both absorption and emission can be witnessed by either observer under suitable conditions. The novelty of tacby- ons is that emission and absorption must be converted into each other by a change in the observer's velocity, and this fin- plies a closer connection between the two processes than exists for ordinary particles. It also finplics that the number of tachyons in some region of space must vary from observer to observer. Suppose one observer views the process of cinis sion of a tachyon by all atorn, Nvith the subsequent escape of the tachyon to in finity. A second observer may -view the same process as the tach oil's coming Y in from outer space and being absorbed by the atom. Hence the two observers will disagree on the number of tachyons present in the past and in the future. Again this situation differs from that for ordinary particles, where the number of particles present at any time is inde- pendent of the observer. A detailed tl)eo- ry of the interaction of wellyons with ATOM A ATOM B TIME 0- > 0 - - - - > to' 0 0 (D- Oo. 0 > > ti, recoiling (broken arrow). At t,, this tachyon is absorbed by atom .4, which jumps to an excited state and al,o recoils. In th6 siltialion the tinic-ordering would be to, tj, t_ To another ob.5erver (righi), for whoin emission and abiorption have been exchanged, tile same process would appear as follows: Atom A is now moying at time tbut is still in its ground state. It emits a tachyon at t.,' and jumps o to an excited state, losing Solne of its translational energy. Alorn B, N%hich is moving and in an excited ~itate at to" absorbs the lachyon at 111, dropping to the ground state and gaining iranstational energy. For this observer tile time sequence would be to I!,% 111. Approved For Release 2000/08/10 : CIA-RDP96-00787ROO0100030001-9 71 MIX-on-111TAII VT7P , R X M7 t v 5 _0 M 0, V T Approved For Relewe 2000/08/10 CIA-RDP96-007WO00100030001-9 energy greater than t%vice TIME the individ- TIME ual particle's rest energy. o > t Assurning that charged tacliyons are CO) 0 o produced, llaw can they be detected and distinguished from other charcred parti- cles that may be produced in the same way, such as an clectron-positrOn pair? A convenient way to do this is to make t? > ti use of the fact that charged tachyons would continuously radiate photons even when passing through empty space. This phenomenon, known as Cerenkov radia- POPULATION OF TAC11YONS tion after the Russian in a region of space physicist who first at any given time would also vary from observer to observer. observed it from electrons One observer Uelt) would in 1937, oc- view the emission of a t. acliyon by an atom at rest, with curs whenever a charged the subsequent recoil object moves to the atom and the escape of the taellyon to infinity. A second observeriew the tacbyon coining through a substance at (right) would v in from outer space a speed bigher and being absorbed by using the atom to lose than the speed of light a moving atom, ca translational energy. in the substance, Thus an electron movinty throu-1i glass 0 0 at a speed greater than about .7 c will emit Cerenkov radiation, since the speed matter, which has not tacliyons indeed exist. of light in glass is about yet been worked The only un- .7 times its val- out, would have to take known factor, apart fromue in free space. Since 'these features their existence, the speed of a into account. is the rate at which tacliyozi is greater than they -would be pro- that of light in duced. Among known particlesfree space, one would the pro- expect the tachyon. H aving convinced ourselvesduction rate varies by to emit Cerenkov radiation that the many orders of even in a existence of faster-tban-lima arti- nitud ht Pi f i t g e. vacuum, and a calculation p or confirms the ns ons, ance, are pro- g cles does not imply any duced quite readily, expectation: The light contradiction whereas neutrinos xvould be emitted of relativity, Nve must are very difficult to at a characteristic angle nevertheless leave produce. Therefore depending onl,~ the detemiination of whereas an experiment on the speed of die taclivon %vhether such ob- with a positive [sce ilhtstra'- ' jects really happen in result could establish tion on opposite pagel. nature to the ex- the existence of Calculation also perimental physicist. tachyons, a negative shows that a tachyon with In the present state result could at best the sanic of theoretical physics establish all tipper charge as an electron there are few cir- limit for the rate at would lose ener,v curnstances in which which tachyons are producedso quickly through Cerenkov theories flatly pre- from the radiation dict that certain objectsparticles involved. Onlythat even if it is produced must exist. In- the demonstra- with a very stead these theories tion that this rate, high energy, its energy generally enable us ill all reactions stud- Nvill drop belm, o to describe various hypotheticalied, is much less than one electr objects, the rate of produc- on volt before it has travelcd and we must determine tion of any other particlesone millimeter. When this by experiment would lead happens, the which objects exist in to the conclusion that Cerenkov radiation will reality, For exam- tacliyons probably no longer in- ple, present theories do not exist at all. elude visible light, whose allow for the de- photolis have 0 scription of particles energies of more than with an electric two electron volts. charge equal to half wo kinds of experimentalInstead the radiation the electron's charole attempt to will consist of infra- T ' and produce and detect tacliyonsred and longer wavelengths, a mass six times the have which are a electron s mass, but we are fairly confidentbeen made so far. These good deal harder to detect. from experi- experiments are In order to ments that no such objectssensitive to different avoid this problem the are to be types of tacliyon Princeton experi- found in nature. We do and use very different menters used the inreniOLIS not, however, methods, and so Scheme Of al- know why this is so, they will be discussed ]owing any tacbyons produced and we may not separately. The to move know until we have more first experiment, whiellthrough a region empty fundamental was done two of matter bLlt theories than we have years acro at Princeton containing an electric now. University by field. The electric The situation with tachyonsTorsten Alviiaer and.Vichaelfield would transfer encrav is similar; N. Kreisler, to charced to settle the issue of was a search for electricallyparticles, but it would their existence one charged not cause ordinary ' turns to the experimentalist.tacliyons. it has been s This is not known for 35 years particles to radiate detectable amount to say, however, that that electrically chargedof light. A tachy-on passing lie inust hope to particles can be through the stumble oil them somewhereproduced in pairs by region, on the other hand, in the uni- the passarre of high- WOLdd 1-CaCh verse. One feature of energy garnina rays (photons)anoequilibrium between all particle theories through gaining enercy 0 ny based on relativity is matter. Nlany of the 0 0 that they imply that kno,6vn types of from the field and losina, enerav throuah if particles of some charged elementary particleradiation, and would therefore type exist Lit all, have been comirme it must he possible to createmade in this way'. It to radiate photons of them from f9llows that if elec- about the equilibri- other particles, providedtrically charged taclivonsum c"nergy. By fixing that enough exist, it should the value of the 0 0 1 energy is available. be possible to produce Rcld, the experimenters For tachyons this thern from plio- were able to condition of having enoughtons. As indicated above,make this cquilibriuni energ is the fact that enerp correspond 0 oy It"' particularly easy to taellyons can occur withto photons of visible satisfy, because fast zero total en- light, thus rnakiwr 0 tachyons have very low. ergy nicans that a pair the radiation easy to energy. It is of them can be detect. theref,pre eas to s ,nerlmen j1 WIS, 0- ftQlL1Jlviaerind Krek- C:~4'2J9't)09q' 0 AZ46,-Y I o q# t R r R.tjc colidffiR . ~ , -c i c q P0q, a pau a ravs rom a r-,. Uoacti% be pl-OdUced ft-0111 o orclinary part M other particles if e 9 g r only be produced by a cesium source. The'se phoLon with all hi-h-criera pha- 0 y o ~tons lift a lead shield cl-q; it is called the will that prevented inissing-mass meth- lin-f., ` the same value in each event, - G1lWQ3QGGft*s pro- ' tM thein fr ? oin reacl ' I 'I "F&Vel - 76p6i 260MOM10' iaCJA-UR1DPPV0 l# ltyt " ~ l reactions among elementaryed, i ssing mass will li-vacuum particles are not have a )i ly. Beyond the s 119 region. contai-ing two examined in a detecting unique parallel plates apparatus (in value butwill vary from event to with an electric ficld our case a bubble chamber)event, between thern [see in -Miich the depending on the angle between illustrafion on iiext mornenturn and energy the pugel. Pairs of of the charged directions of the two neutral parti- charged tachyons could particles in the reactioncles, be produced by can be inea- among other things. Hence those. the photons in passin sured, In sonic fractionevents through the lead, of the reactions containing several neutral parti- and sorne of these would a niuniber of neutral cles escape (since particles will be pro- will in general show a distribution tJiey speed up wbile losingduced in addition to in energy) into the charged parti- the missing mass squared over a rangc the region between the cles observed. These of plates. A photo- neutral particles are values. Since there is no way of know- multiplier tube was used usually not observed ing to detect any directly, and it is a priori whether a given event con- photons radiated by the often not even known tains tachyons passing how many of one or many neutral particles, the through the region. them are produced. By experimenter applying the must combine all events to No positive indication laws of the.conservationobtain of Cercrilwv of cnerg and an oy overall distribution of missing radiation, and hence no momentum, however, it mass evidence for is possible to squared [see illustration on page tachyon production, was tell from the values 77]. found in this measured for the The production of single particles experiment. More precisely,charged particles v.7hetherwill Uic rate of or not any usually stand out as a peak at a production of tachyon neutral particles have specific pairs was found been produced, value in the distribution of miss- to be less than one ten-thousandthand also what the roomenturning of the and en- mass. If there is no such real-, it usu- known rate for producing ergy carried away by allymeans clectron-posi- these particles are. that b the production of a single tron pairs by photons The latter quantities, neutral of slightly higher defined as the dif- particle 0 is improbable compared energy. The mass-energ ference between the energywith relation satis- or momen- the OY production of several neutral fled by taclivons makes turn of the particles particles. it highly unlikely observed going into that this rate can dependthe reaction and the In very sensitively enen, or momen- using Cly the missing mass method to b- on either the photon energyturn of the particles search or the observed emerging for neutral tachyons, we note that tacby6n mass. Therefore from the reaction, are if it seems, with known as the miss- a single neutral tachyon is produced, one qualification to be ing energy and momentuni.the discussed below, If there are missing mass squared is a negative that tacliyons witli a no missing energy and number. charge approxi- momentum in a Furthermore, if two or more mately equal to the electron'sgiven event, it suggestsneutral charge that no other tachyons are produced, the miss- simply do not exist. Tacbyonsparticles have been produced.ing with a mass squared can be either positive charge dilffering from From the missing energy or the electron's and momen- negative depending on the coriEgura- charge by more than a turn in a specific eventtion. factor of two in one car, calculate If the missing mass squared 3 :5 ob- the upward direction or a "missing mass squared"served .1 in the down- for the event. to be negative for any events, ward direction would probablyIf exactly one missing then not have neutral particle necessarily at least one tacliyon been seen in the experiment.has been produced, the must Of course, missing mass have been produced among the uncharged tachyons, whichsquared is the actual neutral would not mass of the parti- particles. In other words, a col- emit Cerenkov radiation, cle squared. A number lection would not have of elementary of ordinary particles cannot have been detected either. particles, such as the a negative neutral eta meson, mass squared. Hence in order have been detected In to this way. The ob- investigate neutral-tachyon. produc- T be qualiflcation tbat vious advantage of the tion must be niade to method is t-hat by means of specific incident parti- these conclusions is thatnothing need be assumed cles, it is uncer- about what the one makes a plot of the missing tain whether or not tachyonsmissing particle does mass might lose after being pro- squared for all events and looks for energy througli processesduced. Its presence is any other than indicated simply events with a neoutive missing mass Cerenkov radiation. One by the mass it represents,squared. such possibility which is in- The production of single tachy- is that a single tacbyon ferred from measurementsons could decay into made on would give a peak in the missing- several tacbyons, each known particles. mass-squared of lower energy, distribution at some nega- If there were such other If a single neutral particletive energy-loss of a spe- value, whereas the production of mechanisms, the amount cific kind is produced, two of Cerenkov the missing mass neutral taebyons,.vould give a broad radiation actually emitted miglit be smaller than the anticipated amount, and the value of the upper limit for the number of tachyons produced would be ,too low. For this reason, and because we are in general ignorant about possible interactions of tacbyons with. matter, it was thotiolit desirable to search for tachyons 311 a manner independent of how they interact after being produced. Such an experiment vvas performed recently by a group at Columbia Uni- versity consisting of Charles Ballay, Ralph Linsker, Nlocl K. Ych and myself. The method used was a ivell-known one for searching for new elementary parti- 0 - - - - - - - - CERENKOV RADIATION would be emitted continuously by an electrically charged tacljy- on moving in a vacuum. The characteristic angle (0) at which the pbotom Wack) would be emitted would depend only on the speed of the tacliyon: the fauer the tachyon, the great. er the angle. Ordinary charge(] partivIcs, such as the electron, emit Cerenkov radiation only when they move through a substance faster than the E~peed of light in the substance. Approved For Release 2000/08/10 : CIA-RDP96-00787ROO0100030001-9 73 An r VeY ForRele e 2009/01 0,-,CJA-RDP96-007$WOOQ1000300.01-9 t, t , P distr7rupioipof tic tota inis 11 mass 10 rc 1 c between the suni of tacliyon-proCILICtion events this sliould s,j e snuared, over both positive and negative initial values for the K meson arid the only reduce the. number by the ratio of values, without any sharp peaks. proton, and the values for the emerging remaining events to total events, where lambda particle, which, as indicated as it should eliminate all spurious ne-ua n our experiment two reactions were studied. In one, negative K mesons were allowed to conic to rest and be cap tured by protons in a hydrogen bubble cbamber. One neutral particle, a lambda hyperon, Was produced and was detect ed through its decay in the bubble cham ber into two charged particles. (The mo mentum and energy of the lambda-par ticle can then be inferred from the mea sured values for the charged particles.) In order to conserve energy and momen turn other neutral particles had to be produced. These were usually a single neutral pion, or sometimes a neutral piort and a photon. The events bad all been analyzed previously for other purposes, so that the momentum and energy of the charges were already measured. A plot of the missing mass squared was made C) for some 6,000 events involving the cap ture of a negative K meson. It should 0 be realized that in this case the missing enerL,v arid momentum are defined as above, can be interrect from its clecay products, even though it is neutral. In our first set of measurements a number of events were found with a negative missing mass squared, which suggested tacliyon production. Caution, bowever, suggested that various tests be made bo- fore this conclusion could be accepted. One test involved making sure that the K mesons were really at rest when captured. If this were not the case, the missing inass squared would be iticor rectly calculated for a given event, since in the calculation it was always assumed that the meson was at rest when cap Lured. If the direction of the lambda par ticle were nearly the same as the actual direction of a K meson captured in flight, then the missing mass squared could be measured as negative when it was really b positive. Accordingly all events in which the angle between the K meson and the lambda particle was less than 60 degrees were removed from the sarnole. For true tive-mass-squared events due to capture in flight. WLen this test was carried out, the number of events xvith negative miss- ing mass squared %vas reduced to 203 from an original total of 101, indicat- ing that most of the supposed tachyor, events were actually captures in Right, producing ordinary particles. The remaining events were carefullv remeasured to ensure that the missing mass squared had been correctly mea- sured. It was found in each case that the true missing mass squared was positive or zero, within tbe precision of the rnca- surements. Hence what was originally a substantial number of taebyon-candidate events was reduced, after careful study to none at all. By compaxing the limit on tacliyon production (less than one) with the total number of events seen, most of which had a missing mass squared rep- resented by a neutral pion, it can be in- ferred that the rate of tachyon produc- tion is less than one nart in 400 of the PHOTOMULTIPLIER EXPERIMENT designed to detect eltarged tachyons by means of their Cerenkoy radiation was carried out two years ago by Torziten AMgcr and 11licliael N. Kreisler at Princeton University. They used a radioactive cesitun source to provide bigh-energy gamma rays (y), wbich were allowed to bit a lead shield that prevented flieni from rcacliing the detection apl)aratui directly. Pairs of char-ed tachyons c I I I d iced by the gannua ra i)hoton in , c pasApprn 0"' W, sO~~:iG]A-REDR86~,007d87ROODIOD030001~,,,9!n 'QJr ~MWtag Vied F high-vacuum region, which contained two pai-allel 14ates with an electric field between theru.'T lie purpose of theeleoric fivid wa, to transfer just enough energy if) the. raclivons to compensate. for tLe energy they lost throu~,b radiation, tbu6 ena!Aing them ta conzin"'-'~ to radiate photons of viAble light. A photoniultiplier tube was v--ecl to detect any Ototom, radiated by the tachyons Passfing- throm'-d' this region. No positive indication of Cerenkov radialion (2nd oli, everlilli-1, pion productiol, Jat(Appmoivq0i(FDr Rel a stron(y production process. 0f course, the tactly"'.1 proauction rate was also consistent with zero. A siniflar scarch by the saine group, cirried out on the annihilationC) Of anti- protons with piotons, gave no examples ()f tacliyon production -and a siniflarly low linlit for the rate of taclivoll produc- tion. in that reaction. In each of [lie ex- perinients single tachyons could be pro- 0 L) duced only if their inass squared was Nvithin a spccific range 0 of values, and C" hence the experiment tested single- U ,acliyon production only for particles in that inass range. There Ll arc reasons to Z believe, however, that o sinale.-tachyon production is forbidden anyway, just as single pi,oduction of elcc~roils vvith- cl~ out Other similar particles- is forbidden. Nonetheless, production c~r of two tachy- ons, or of -taclivoil-antitaellyonow Pairs, is. not so forbidde;t. Such 0 two-partielc pro- duction could occur in u;;'-j either experiment > no matter what the squaredLU inass of (lie individual tach-vons was, and so the ex- nerinients actually put ta~ rather sharp lini- Lu 1. its on the production of taclivons of any inass, except for values so near zero that theyare within the experimental error of being positive. oth of the direct experimental search- es for tachvons that bave been car- ded out liave tflerefore yielded negative o results. Ji)diroct arguments have also 0 tended to restrict stil.1 further the pos- sible interactions of tacliyons. According to one of these arguments, if charged iaclivons exist, the photon Nvould not be a stable object but instead -would decay Nvithin sonic tirne period into a pair of charged taclivons. We know that plio- tons can travel for billions of Years across intergalactic space Nvithout so decaying. This implies that if charged tacliyons exist at all, then either their charge is many orders of inagiiitude sinaller tban that of (lie electron, whicli nicans that they interact very Nveakly with photons, or else their inass squared is very close to zero, -whicli makes them difficult to distinguish front ordinary particles. Sim- ilar conclusions can be dravvii froni in- direct arguments about the %,cry sniall ii,teractiolls Of neutral taellyous. The possibility that tacliyous exist but do not interact at all with ordinary par- iieles need not concern us, because if they do not interact: with dic objects that _0111pose our ineasuring histruinents, we Jmve 110 possible way to detect them, and -.or our pulposes it is the saine as if they ,A) not exist at all. If we plausibly interpret the above Approved For 10 15 10 0 -.15 _1 -.05 0 .05 .1 MISSING MASS SQUARED (BILLIONS OF ELECTRON VOLTS SQUA;':_D) 11T-~SULTS of the analysis by the author and his colleagues at Columbia of so'nic 6,000 bubble-chaniber events involving the capture of a negative K meton are presented here in the form of two curves representing the overall distribution of mist-ing niass squared for all events in terms of its energy equivalent in hillions of electron volts squared. The highest peak in each case corresponds to the production Of ,iDgIC neutral pions. The production of sinle neutral tachyons would result in a similar peak at some negative value of ini.,sing mas, squared, whereas the production of two neutral tachyons would give a broad di~~tribu- tion of the total missing mass squared over both positive and negative values %ithout any sharp peaks. In an early set "of measurements (lop) a number of events were found with a negative missing mass squared, uhich suggested tachyon production. In a sub~~equent test (bottom), which involved rechecking sonic of the nicasurenients, the number of events with negative missing mass squared was reduced to cs25entiallv zero, indicating that moat of the supposed tacliyon events were actually errors in the' fir&t set of mea,urellients. results to conclude that tocliyons cainiot nomena, such as costnic rays. A difficulty be produced at all from ordinary parti- in carrying out such a search is that cles, we secin to be left with two possi- tachyons should lose energy rapidly and bilities. One remote possibility is that become hard to detect. The seconci pos- tacliyons do interact vvith ordinary par- sibility is that tachyons simply do not ticles and cai) exchange energy with exist , and that nature has not filled the thein but cannot be produced froin thern. niche that is allowed by the theory of This situation would stronlgly contradict relativity. If this is--the case,, as 110W all our experience with relativistic quan- seenis probable, we inay not understand tum theories of particles, and so it is fin- why it should be so until we reach a probable but perhaps not impossible. much deeper understanding of the na- 'flie hypothesis could be tested by ture of clenlentary particles than no\\., scarchinu for tachyons in natural phe- C X. Is t S, Release 2000/08/10 : CIA-RDP96-00787ROO0100030001-9