Collection

# Physics: Looking Back...

Since 1869, Nature has published some of the world's most important physics and astrophysics research, including the discovery of the neutron, the first laser, the discovery of superfluidity, the explanation of quasars, the invention of holography, and much more...

These papers are well worth revisiting, as much for their elegance and brevity as for their seminal content.

## Content

• ### Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid

• J. D. WATSON
• F. H. C. CRICK
Article
• ### Experimental quantum teleportation

Quantum teleportation — the transmission and reconstruction over arbitrary distances of the state of a quantum system — is demonstrated experimentally. During teleportation, an initial photon which carries the polarization that is to be transferred and one of a pair of entangled photons are subjected to a measurement such that the second photon of the entangled pair acquires the polarization of the initial photon. This latter photon can be arbitrarily far away from the initial one. Quantum teleportation will be a critical ingredient for quantum computation networks.

• Dik Bouwmeester
• Jian-Wei Pan
• Anton Zeilinger
Article
• ### New Experiments on the Kathode Rays1

(1) TWO hypotheses have been propounded to explain the properties of the kathode rays. Some physicists think with Goldstein, Hertz, and Lenard, that this phenomenon is like light, due to vibrations of the ether,2 or even that it is light of short wavelength. It is easily understood that such rays may have a rectilinear path, excite phosphorescence, and affect photographic plates.

News

LONDON. Royal Society, February 18.—“On the Significance of Bravais' Formulæ for Regression, Άc, in the case of Skew Correlation.” By G. Udny Yule. Received December 14, 1896.

News
• ### Observations with Electron-Sensitive Plates Exposed to Cosmic Radiation*

PART 2. FURTHER EVIDENCE FOR THE EXISTENCE OF UNSTABLE CHARGED PARTICLES, OF MASS ∼ 1,000 me, AND OBSERVATIONS ON THEIR MODE OF DECAY

• R. BrownMiss
• U. Camerini
• D. M. Ritson
Article
• ### Decay of V-Particles

• R. ARMENTEROS
• K. H. BARKER
• A. H. CHAPMAN
Article
• ### Existence of Electromagnetic-Hydrodynamic Waves

IF a conducting liquid is placed in a constant magnetic field, every motion of the liquid gives rise to an E. M. F. which produces electric currents. Owing to the magnetic field, these currents give mechanical forces which change the state of motion of the liquid. Thus a kind of combined electromagnetic-hydro-dynamic wave is produced which, so far as I know, has as yet attracted no attention.

• H. ALFVÉN
Letter
• ### Possible gravitational microlensing of a star in the Large Magellanic Cloud

THERE is now abundant evidence for the presence of large quantities of unseen

matter surrounding normal galaxies, including our own1,2. The nature of

this ’dark matter‘ is unknown, except that it cannot be made of normal stars,

dust or gas, as they would be easily detected. Exotic particles such as axions, massive

neutrinos or other weakly interacting massive particles (collectively known as WIMPs)

have been proposed3,4, but have yet to be detected. A less exotic

alternative is normal matter in the form of bodies with masses ranging from that of a

large planet to a few solar masses. Such objects, known collectively as massive compact

halo objects5 (MACHOs), might be brown dwarfs or ‘jupiters’

(bodies too small to produce their own energy by fusion), neutron stars, old white dwarfs

or black holes. Paczynski6 suggested that MACHOs might act as

gravitational microlenses, temporarily amplifying the apparent brightness of background

stars in nearby galaxies. We are conducting a microlensing experiment to determine

whether the dark matter halo of our Galaxy is made up of MACHOs. Here we report a

candidate for such a microlensing event, detected by monitoring the light curves of 1.8

million stars in the Large Magellanic Cloud for one year. The light curve shows no

variation for most of the year of data taking, and an upward excursion lasting over 1

month, with a maximum increase of ∼2 mag. The most probable lens mass, inferred from

the duration of the candidate lensing event, is ∼0.1 solar mass.

• C. Alcock
• C. W. Akerlof
• W. Sutherland
Letter
• ### Evidence for gravitational microlensing by dark objects in the Galactic halo

THE flat rotation curves of spiral galaxies, including our own, indicate that

they are surrounded by unseen haloes of ‘dark matter’1,2. In

the absence of a massive halo, stars and gas in the outer portions of a galaxy would

orbit the centre more slowly, just as the outer planets in the Solar System circle the

Sun more slowly than the inner ones. So far, however, there has been no direct

observational evidence for the dark matter, or its characteristics.

Paczyński3suggested that dark bodies in the halo of our Galaxy can

be detected when they act as gravitational ‘microlenses’, amplifying the

light from stars in nearby galaxies. The duration of such an event depends on the mass,

distance and velocity of the dark object. We have been monitoring the brightness of three

million stars in the Large Magellanic Cloud for over three years, and here report the

detection of two possible microlensing events. The brightening of the stars was

symmetrical in time, achromatic and not repeated during the monitoring period. The

timescales of the two events are about thirty days and imply that the masses of the

lensing objects lie between a few hundredths and one solar mass. The number of events

observed is consistent with the number expected if the halo is dominated by objects with

masses in this range.

• E. Aubourg
• P. Bareyre
• C. Gry
Letter
• ### 0957 + 561 A, B: twin quasistellar objects or gravitational lens?

0957 + 561 A, B are two QSOs of mag 17 with 5.7 arc s separation at redshift 1.405. Their spectra leave little doubt that they are associated. Difficulties arise in describing them as two distinct objects and the possibility that they are two images of the same object formed by a gravitational lens is discussed.

• D. Walsh∗
• R. F. Carswell†
• R. J. Weymann‡
Article
• ### Detection of Neutrons Liberated from Beryllium by Gamma Rays: a New Technique for Inducing Radioactivity

We have observed that a radiation emitted from beryllium under the influence of radium gamma rays excites induced radioactivity in iodine, and we conclude that neutrons are liberated from beryllium by gamma rays.

• LEO SZILARD
• T. A. CHALMERS
Letter
• ### Liberation of Neutrons from Beryllium by X-Rays: Radioactivity Induced by Means of Electron Tubes

IT has been recently reported1 that neutrons are liberated from beryllium by -rays of radium and that these are able to induce radioactivity in iodine. Following up this work, we have attempted to liberate neutrons from beryllium by means of hard X-rays, produced by high-voltage electron tubes. An electron tube, which could conveniently be operated by a high-voltage impulse generator at several million volts2, is at present in use in the High Tension Laboratory of the A.E.G. in Berlin, and has served in the present experiment for the production of X-rays.

• A. BRASCH
• F. LANGE
• F. L. HOPWOOD
Letter
• ### Detection of Water in Interstellar Regions by its Microwave Radiation

A report of the detection of microwave radiation from water molecules in space, by the group which recently detected interstellar ammonia emission.

• A. C. CHEUNG
• D. M. RANK
• W. J. WELCH
Article
• ### Correlation between Photons in two Coherent Beams of Light

• R. HANBURY BROWN
• R. Q. TWISS
Article
• ### Spiral Growth on Carborundum Crystal Faces

The theory of crystal growth based on dislocation theory as formulated by F. C. Frank1 predicts the presence of growth features in the form of very flat, spirally terraced hills on the crystal face which is perpendicular to a screw dislocation line.

• S. AMELINCKX
Letter
• ### A Floating Magnet

BY assuming that diamagnetic bodies are pushed out of a magnetic field, it may be shown that a diamagnetic particle attracted to a magnet by gravitational forces will take up a position in space in the equatorial plane of the straight magnet at a certain distance from the latter. The ‘satellite’ can vibrate elastically about the point of equilibrium, describing a certain curve. The period of vibration in the radial and meridional directions is close to the period of the Kepler rotation of a magnetically indifferent satellite about a body of the same mass. Several identical particles arrange themselves around the magnet. Such a combination of bodies is in the nature of a static planetary system as distinct from the Kepler dynamic planetary system.

Letter
• ### Neutrinos from the recent LMC supernova

• J. N. BAHCALL
• A. DAR
• T. PIRAN
Scientific Correspondence
• ### Upper limit on the mass of the electron neutrino

The historic detection by the Kamiokande-II collaboration1 and the IMB collaboration2 of neutrinos from the Large Magellanic Cloud (LMC) supernova provides the first opportunity to determine the mass, ${m}_{{v}_{\text{c}}}$ , of the electron neutrino from astronomical observations. Here we show that ${m}_{{v}_{\text{c}}}$ , is less than 11 eV, provided only that propagation effects have not conspired to sharpen, by more than a factor of two the narrow pulse-width of neutrinos, observed by the Kamiokande-II collaboration from the LMC supernova. This result improves on the laboratory limit on ${m}_{{v}_{\text{c}}}$ and confirms the view that electron neutrinos do not constitute the major component of the matter density of the Universe.

• J. N. Bahcall
• S. L. Glashow
Letter
• ### Density of Nitrogen

I AM much puzzled by some recent results as to the density of nitrogen, and shall be obliged if any of your chemical readers can offer suggestions as to the cause. According to two methods of preparation I obtain quite distinct values. The relative difference, amounting to about 1/1000 part, is small in itself; but it lies entirely outside the errors of experiment, and can only be attributed to a variation in the character of the gas.

• RAYLEIGH
Letter
• ### Nature of the Nuclear Field

AN attempt to explain neutron-proton interaction made by Yukawa1 in 1935 has been brought to general notice2,3 in connexion with the new experimental evidence for the existence of a 'heavy electron'4,5,6.

• N. KEMMER
Letter
• ### Nuclear Forces, Heavy Electrons and the β-Decay

WE have generalized a theory put forward by Yukawa1 showing that nuclear forces can be explained by assuming the existence of new particles of mass about two hundred times that of the electron. Our theory is relativistically invariant, and in its present form gives results which we believe are of actual significance for cosmic ray and nuclear phenomena.

• H. J. BHABHA
Letter
• ### Light-emitting diodes based on conjugated polymers

CONJUGATED polymers are organic semiconductors, the semiconducting behaviour being associated with the π molecular orbitals delocalized along the polymer chain. Their main advantage over non-polymeric organic semiconductors is the possibility of processing the polymer to form useful and robust structures. The response of the system to electronic excitation is nonlinear—the injection of an electron and a hole on the conjugated chain can lead to a self-localized excited state which can then decay radiatively, suggesting the possibility of using these materials in electroluminescent devices. We demonstrate here that poly(p-phenylene vinylene), prepared by way of a solution-processable precursor, can be used as the active element in a large-area light-emitting diode. The combination of good structural properties of this polymer, its ease of fabrication, and light emission in the green–yellow part of the spectrum with reasonably high efficiency, suggest that the polymer can be used for the development of large-area light-emitting displays.

• J. H. Burroughes
• A. B. Holmes
Letter
• ### A New Conception of Supraconductivity

IN the past few years, physicists have been much engaged by the phenomenon of supraconductivity. It is well known that various metals, when cooled below a certain very low temperature, characteristic of the metal in question, show the strange property of conducting electricity apparently without offering any resistance to the current. This curious phenomenon seems to contradict all our customary conceptions in physics. Particularly striking was the experiment of Kamerlingh Onnes and Tuyn, in which a current was induced in a supraconducting ring of lead and was found to persist there without any measurable decrease for many hours—so long as the low temperature could be maintained. This experiment seems to present a unique case of motion without any friction, whilst we have been accustomed to see in every mechanism an occasion for dissipation of kinetic energy into heat.

• F. London
News
• ### A New Conception of Supraconductivity *

5. According to these conceptions, there cannot exist any magnetic flux 'frozen' in the interior of pure supraconductors ; a permanent flux should only be found confined to the hollows of supra-conducting rings. The topological connectivity of a supraconductor, therefore, is a property extremely characteristic of its behaviour: the multiplicity of its connectivity, diminished by one, immediately indicates the number of independent conservative quantities, that is, of independent invariant magnetic fluxes.

• F. London
News
• ### Experimental Proof of the Spin of the Photon

IN a paper under this title which has recently appeared,1 we have described and discussed observations which have led us to the conclusion that the light quantum possesses an intrinsic spin equal to one Bohr unit of angular momentum. In the four weeks which have elapsed since that paper was put into print, the experimental technique has been much improved in the direction of attaining greater precision. It appears desirable forthwith to report our newer results, which confirm the conclusion stated above.

• C. V. RAMAN
• S. BHAGAVANTAM
Letter
• ### Notes

MESSAGES from Newfoundland announce that Mr. Marconi has succeeded in signalling from England to America by wireless telegraph. Detailed information is not yet available, but it is said that the signals which were received at St. John’s, three on Thursday and one on Friday last, though faint were unmistakable, and that Mr. Marconi intends to come immediately to England to increase the power of his transmitters at Poldhu, Cornwall, in order to establish more satisfactory communication across the Atlantic. According to later information the Anglo-American Telegraph Company have given Mr. Marconi notice to remove his instruments from the Colony, as they possess a fifty years' telegraphic monopoly, of which there are still two years to run. This will involve the removal of his experimental Station to Nova Scotia or to some other convenient place on the American coast line, and may, perhaps, somewhat delay further experiments. It is to be hoped, however, that we shall before long see a further development of Mr. Marconi’s remarkable achievement, upon which if confirmed by subsequent results he cannot be too warmly congratulated. It is interesting to compare the possible rapid development of wireless telegraphy in Mr. Marconi’s hands with that of the ordinary telegraph. The first Atlantic cable was not laid until five-and-twenty years after the invention of the telegraph by Gauss and Weber. The earliest proposal to use Hertz waves for signalling was made in 1891, and Mr. Marconi began his experiments four or five years later; at that time he was able to signal two or three miles, and now, after five years' work, he claims to have succeeded in increasing this distance a thousandfold.

Miscellany
• ### Intra-atomic Charge

THAT the intra-atomic charge of an element is determined by its place in the periodic table rather than by its atomic weight, as concluded by A. van der Broek (NATURE, November 27, p. 372), is strongly supported by the recent generalisation as to the radio-elements and the periodic law. The successive expulsion of one and two particles in three radio-active changes in any order brings the intra-atomic charge of the element back to its initial value, and the element back to its original place in the table, though its atomic mass is reduced by four units. We have recently obtained something like a direct proof of van der Broek’s view that the intra-atomic charge of the nucleus of an atom is not a purely positive charge, as on Rutherford’s tentative theory, but is the difference between a positive and a smaller negative charge.

• FREDERICK SODDY
Letter
• ### The Structure of the Atom

IN a letter to this journal last week, Mr. Soddy has discussed the bearing of my theory of the nucleus atom on radio-active phenomena, and seems to be under the impression that I hold the view that the nucleus must consist entirely of positive electricity. As a matter of fact, I have not discussed in any detail the question of the constitution of the nucleus beyond the statement that it must have a resultant positive charge. There appears to me no doubt that the α particle does arise from the nucleus, and I have thought for some time that the evidence points to the conclusion that the particle has a similar origin. This point has been discussed in some detail in a recent paper by Bohr (Phil. Mag., September, 1913). The strongest evidence in support of this view is, to my mind, (1) that the β ray, like the α ray, transformations are independent of physical and chemical conditions, and (2) that the energy emitted in the form of β and γ rays by the transformation of an atom of radium C is much greater than could be expected to be stored up in the external electronic system. At the same time, I think it very likely that a considerable fraction of the rays which are expelled from radioactive substances arise from the external electrons. This, however, is probably a secondary effect resulting from the primary expulsion of a β particle from the nucleus.

• E. RUTHERFORD
Letter
• ### Flux quantization in a high-Tc superconductor

• C. E. Gough
• M. S. Colclough
• S. Sutton
Letter
• ### Thermal Agitation of Electricity in Conductors

ORDINARY electric conductors are sources of spontaneous fluctuations of voltage which can be measured with sufficiently sensitive instruments. This property of conductors appears to be the result of thermal agitation of the electric charges in the material of the conductor.

• J. B. JOHNSON
Letter
• ### The Problem of the Random Walk

CAN any of your readers refer me to a work wherein I should find a solution of the following problem, or failing the knowledge of any existing solution provide me with an original one? I should be extremely grateful for aid in the matter.

• KARL PEARSON
Letter
• ### The Problem of the Random Walk

THIS problem, proposed by Prof. Karl Pearson in the current number of NATURE, is the same as that of the composition of n iso-periodic vibrations of unit amplitude and of phases distributed at random, considered in Phil. Mag., x., p. 73, 1880; xlvii., p. 246, 1899; (“Scientific Papers,” i., p. 491, iv., p. 370). If n be very great, the probability sought is

• RAYLEIGH
Letter
• ### The Problem of the Random Walk

I HAVE to thank several correspondents for assistance in this matter. Mr. G. J. Bennett finds that my case of n = 3 can really be solved by elliptic integrals, and, of course, Lord Rayleigh’s solution for n very large is most valuable, and may very probably suffice for the purposes I have immediately in view. I ought to have known it, but my reading of late years has drifted into other channels, and one does not expect to find the first stage in a biometric problem provided in a memoir on sound. From the purely mathematical standpoint, it would still be very interesting to have a solution for n comparatively small. The sections through the axis of Lord Rayleigh’s frequency surface for n large are simply the “cocked hat” or normal curve of errors type; for n = 2 or 3 they do not resemble this form at all. For n=2, for example, the sections are of the form of a double U, thus UU, the whole being symmetrical about the centre vertical corresponding to r = 0, but each U itself being asymmetrical. The system has three vertical asymptotes. It would be interesting to see how the multiplicity of types for n small passes over into the normal curve of errors when n is made large.

• KARL PEARSON
Letter
• ### Helical microtubules of graphitic carbon

THE synthesis of molecular carbon structures in the form of C60 and other fullerenes1 has stimulated intense interest in the structures accessible to graphitic carbon sheets. Here I report the preparation of a new type of finite carbon structure consisting of needle-like tubes. Produced using an arc-discharge evaporation method similar to that used for fullerene synthesis, the needles grow at the negative end of the electrode used for the arc discharge. Electron microscopy reveals that each needle comprises coaxial tubes of graphitic sheets, ranging in number from 2 up to about 50. On each tube the carbon-atom hexagons are arranged in a helical fashion about the needle axis. The helical pitch varies from needle to needle and from tube to tube within a single needle. It appears that this helical structure may aid the growth process. The formation of these needles, ranging from a few to a few tens of nanometres in diameter, suggests that engineering of carbon structures should be possible on scales considerably greater than those relevant to the fullerenes.

• Sumio Iijima
Letter
• ### A Jupiter-mass companion to a solar-type star

The presence of a Jupiter-mass companion to the star 51 Pegasi is inferred from observations of periodic variations in the star’s radial velocity. The companion lies only about eight million kilometres from the star, which would be well inside the orbit of Mercury in our Solar System. This object might be a gas-giant planet that has migrated to this location through orbital evolution, or from the radiative stripping of a brown dwarf.

• Michel Mayor
• Didier Queloz
Article
• ### The Continuous Spectrum of β-Rays

THE continuous spectrum of the β-rays arising from radio-active bodies is a matter of great importance in the study of their disintegration. Two opposite views have been held about the origin of this continuous spectrum. It has been suggested that, as in the α-ray case, the nucleus, at each disintegration, emits an electron having a fixed characteristic energy, and that this process is identical for different atoms of the same body. The continuous spectrum given by these disintegration electrons is then explained as being due to secondary effects, into the nature of which we need not enter here. The alternative theory supposes that the process of emission of the electron is not the same for different atoms, and that the continuous spectrum is a fundamental characteristic of the type of atom disintegrating. Discussion of these views has hitherto been concerned with the problem of whether or not certain specified secondary effects could produce the observed heterogenity, and although no satisfactory explanation has yet been given by the assumption of secondary effects, it was most important to clear up the problem by a direct method.

• C. D. ELLIS
• W. A. WOOSTER
Letter
• ### The Neutrino

• FREDERICK REINES
• CLYDE L. COWANjun.
Article
• ### A Three-Dimensional Model of the Myoglobin Molecule Obtained by X-Ray Analysis

• J. C. Kendrew
• G. Bodo
• D. C. Phillips
Article
• ### The Neutron Hypothesis

DR. J. CHADWICK’s explanation1 of the mysterious beryllium radiation is very attractive to theoretical physicists. Is it not possible to admit that neutrons play also an important rôle in the building of nuclei, the nuclei electrons being all packed in α-particles or neutrons ? The lack of a theory of nuclei makes, of course, this assumption rather uncertain, but perhaps it sounds not so improbable if we remember that the nuclei electrons profoundly change their properties when entering into the nuclei, and lose, so to say, their individuality, for example, their spin and magnetic moment.

• D. IWANENKO
Letter
• ### Black hole explosions?

QUANTUM gravitational effects are usually ignored in calculations of the formation and evolution of black holes. The justification for this is that the radius of curvature of space-time outside the event horizon is very large compared to the Planck length (Għ/c3)1/2 ≈ 10−33 cm, the length scale on which quantum fluctuations of the metric are expected to be of order unity. This means that the energy density of particles created by the gravitational field is small compared to the space-time curvature. Even though quantum effects may be small locally, they may still, however, add up to produce a significant effect over the lifetime of the Universe ≈ 1017 s which is very long compared to the Planck time ≈ 10−43 s. The purpose of this letter is to show that this indeed may be the case: it seems that any black hole will create and emit particles such as neutrinos or photons at just the rate that one would expect if the black hole was a body with a temperature of (κ/2π) (ħ/2k) ≈ 10−6 (M/M)K where κ is the surface gravity of the black hole1. As a black hole emits this thermal radiation one would expect it to lose mass. This in turn would increase the surface gravity and so increase the rate of emission. The black hole would therefore have a finite life of the order of 1071 (M/M)−3 s. For a black hole of solar mass this is much longer than the age of the Universe. There might, however, be much smaller black holes which were formed by fluctuations in the early Universe2. Any such black hole of mass less than 1015 g would have evaporated by now. Near the end of its life the rate of emission would be very high and about 1030 erg would be released in the last 0.1 s. This is a fairly small explosion by astronomical standards but it is equivalent to about 1 million 1 Mton hydrogen bombs.

• S. W. HAWKING
Letter
• ### The Dynamics of a Golf Ball 1

THERE are so many dynamical problems connected with golf that a discussion of the whole of them would occupy far more time than is at my disposal this evening. I shall not attempt to deal with the many important questions which arise when we consider the impact of the club with the ball, but confine myself to the consideration of the flight of the ball after it has left the club. This problem is in any case a very interesting one; it would be even more interesting if we could accept the explanations of the behaviour of the ball given by many contributors to the very voluminous literature which has collected round the game; if these were correct, I should have to bring before you this evening a new dynamics, and announce that matter, when made up into golf balls, obeys laws of an entirely different character from those governing its action when in any other condition.

News
• ### Some Points in the Physics of Golf

IT is not an easy matter to determine the initial speed of a golf-ball:—but this is so only because the direct processes which have given us so much information about the flight of military projectiles are here practically inapplicable. No doubt, a ballistic pendulum, or a Bash-forth chronograph, might after long and tantalizing experiment give us the desired information. If they did, they would give it much more accurately than we are otherwise likely to obtain it. But the circumstances of a “drive” at cricket or golf are so uncertain, even with the best of players, that it would be waste of time, and wanton vexation of spirit, to employ these instruments of precision. Yet the questions involved are of a very interesting kind, not only from the purely physical point of view but also in consequence of the recent immense development of these national games; so that there is considerable inducement to attempt at least a rough solution of some of them.

• P. G. TAIT
Editorial
• ### A Nuclear Photo-effect: Disintegration of the Diplon by -Rays

BY analogy with the excitation and ionisation of atoms by light, one might expect that any complex nucleus should be excited or ‘ionised’, that is, disintegrated, by γ-rays of suitable energy. Disintegration would be much easier to detect than excitation. The necessary condition to make disintegration possible is that the energy of the γ-ray must be greater than the binding energy of the emitted particle. The γ-rays of thorium C″ of hv = 2.62 × 106 electron volts are the most energetic which are available in sufficient intensity, and therefore one might expect to produce disintegration with emission of a heavy particle, such as a neutron, proton, etc., only of those nuclei which have a small or negative mass defect; for example, D2, Be9, and the radioactive nuclei which emit a-particles. The emission of a positive or negative electron from a nucleus under the influence of γ-rays would be difficult to detect unless the resulting nucleus were radioactive.

• M. Goldhaber
News
• ### Charged Particles in a Non-uniform Radio-frequency Field

AN analysis of the motion of a charged particle in a non-uniform radio-frequency field has been made and has shown that under certain conditions particles of either sign will experience an acceleration towards the position of least electric field strength.

• H. A. H. BOOT
• R. B. R.-S.-HARVIE
Letter
• ### Distant Electric Vision

REFERRING to Mr. Shelford Bidwell’s illuminating communication on this subject published in NATURE of June 4, may I point out that though, as stated by Mr. Bidwell, it is wildly impracticable to effect even 160,000 synchronised operations per second by ordinary mechanical means, this part, of the problem of obtaining distant electric vision can probably be solved by the employment of two beams of kathode rays (one at the transmitting and one at the receiving station) synchronously deflected by the varying fields of two electromagnets placed at right angles to one another and energised by two alternating electric currents of widely different frequencies, so that the moving extremities of the two beams are caused to sweep synchronously over the whole of the required surfaces within the one-tenth of a second necessary to take advantage of visual persistence.

• A. A. CAMPBELL SWINTON
Letter
• ### Observation of a Line in the Galactic Radio Spectrum: Radiation from Galactic Hydrogen at 1,420 Mc./sec.

• H. I. Ewen
• E. M. Purcell
Article
• ### The Constitution of the Elements

IT will doubtless interest readers of NATURE to know that other elements besides neon (see NATURE for November 27, p. 334) have now been analysed in the positive-ray spectrograph with remarkable results. So far oxygen, methane, carbon monoxide, carbon dioxide, neon, hydrochloric acid, and phosgene have been admitted to the bulb, in which, in addition, there are usually present other hydrocarbons (from wax, etc.) and mercury.

• F. W. ASTON
Letter

• M. SCHMIDT
Article
• ### NUCLEAR DISINTEGRATIONS PRODUCED BY SLOW CHARGED PARTICLES OF SMALL MASS

IN studying photographic plates exposed to the cosmic rays, we have found a number of multiple disintegrations each of which appears to have been produced by the entry of a slow charged particle into a nucleus. Mosaics of photomicrographs of three of these events are given in Figs. 1, 2 and 3. The edges of the individual photographs have not been trimmed so that the components of the mosaics can be distinguished. Three grains of a track in Fig. 1, indicated by three arrows, which were out of focus in the original negatives, have been blackened with ink, but the photographs are otherwise completely unretouched.

• G. P. S. Occhialini
• C. F. Powell
Article
• ### Observations on the Tracks of Slow Mesons in Photographic Emulsions*

Introduction. In recent experiments, it has M. been shown that charged mesons, brought to rest A in photographic emulsions, sometimes lead to the production of secondary mesons. We have now extended these observations by examining plates exposed in the Bolivian Andes at a height of 5,500 m., and have found, in all, forty examples of the process leading to the production of secondary mesons. In eleven of these, the secondary particle is brought to rest in the emulsion so that its range can be determined. In Part 1 of this article, the measurements made on these tracks are described, and it is shown that they provide evidence for the existence of mesons of different mass. In Part 2, we present further evidence on the production of mesons, which allows us to show that many of the observed mesons are locally generated in the ‘explosive’ disintegration of nuclei, and to discuss the relationship of the different types of mesons observed in photographic plates to the penetrating component of the cosmic radiation investigated in experiments with Wilson chambers and counters.

• C. M. G. LATTES
• G. P. S. OCCHIALINIDR.
• C. F. POWELLDR.
Article
• ### Wave Mechanics and Radioactive Disintegration

AFTER the exponential law in radioactive decay had been discovered in 1902, it soon became clear that the time of disintegration of an atom was independent of the previous history of the atom and depended solely on chance. Since a nuclear particle must be held in the nucleus by an attractive field, we must, in order to explain its ejection, arrange for a spontaneous change from an attractive to a repulsive field. It has hitherto been necessary to postulate some special arbitrary ‘instability’ of the nucleus; but in the following note it is pointed out that disintegration is a natural consequence of the laws of quantum mechanics without any special hypothesis.

• RONALD W. GURNEY
• EDW. U. CONDON
Letter
• ### The Effect of Magnetisation on the Nature of Light Emitted by a Substance

IN consequence of my measurements of Kerr’s magneto-optical phenomena, the thought occurred to me whether the period of the light emitted by a flame might be altered when the flame was acted upon by magnetic force. It has turned out that such an action really occurs. I introduced into an oxyhydrogen flame, placed between the poles of a Ruhmkorff’s electromagnet, a filament of asbestos soaked in common salt. The light of the flame was examined with a Rowland’s grating. Whenever the circuit was closed both D lines were seen to widen.

• P. ZEEMAN
News
• ### Electronic Digital Computers

A SMALL electronic digital computing machine has been operating successfully for some weeks in the Royal Society Computing Machine Laboratory, which is at present housed in the Electrical Engineering Department of the University of Manchester. The machine is purely experimental, and is on too small a scale to be of mathematical value. It was built primarily to test the soundness of the storage principle employed and to permit experience to be gained with this type of machine before embarking on the design of a full-size machine. However, apart from its small size, the machine is, in principle, 'universal' in the sense that it can be used to solve any problem that can be reduced to a programme of elementary instructions ; the programme can be changed without any mechanical or electro-mechanical circuit changes.

• F. C. WILLIAMS
• T. KILBURN
Letter
• ### Solid C60: a new form of carbon

A new form of pure, solid carbon has been synthesized consisting of a somewhat disordered hexagonal close packing of soccer-ball-shaped C60 molecules. Infrared spectra and X-ray diffraction studies of the molecular packing confirm that the molecules have the anticipated 'fullerene' structure. Mass spectroscopy shows that the C70 molecule is present at levels of a few per cent. The solid-state and molecular properties of C60 and its possible role in interstellar space can now be studied in detail.

• W. Krätschmer
• Lowell D. Lamb
• Donald R. Huffman
Article

• F. P. BUNDY
• H. T. HALL
• R. H. WENTORFJUN.
Article
• ### Errors in diamond synthesis

• H. P. Bovenkerk
• F. P. Bundy
• R. H. WentorfJr
Scientific Correspondence
• ### A Brief Outline of the Development of the Theory of Relativity

[Translated by Dr. Robert W. Lawson.] THERE is something attractive in presenting the evolution of a sequence of ideas in as brief a form as possible, and yet with a completeness sufficient to preserve throughout the continuity of development. We shall endeavour to do this for the Theory of Relativity, and to show that the whole ascent is composed of small, almost self-evident steps of thought.

• A. EINSTEIN
News
• ### A planetary system around the millisecond pulsar PSR1257 + 12

• A. Wolszczan
• D. A. Frail
Letter

• D. GABOR
News
• ### The λ-Phenomenon of Liquid Helium and the Bose-Einstein Degeneracy

IN a recent paper1 Fröhlich has tried to interpret the λ-phenomenon of liquid helium as an order–disorder transition between n holes and n helium atoms in a body-centred cubic lattice of 2n places. He remarks that a body-centred cubic lattice may be considered as consisting of two shifted diamond lattices, and he assumes that below the λ-point the helium atoms prefer the places of one of the two diamond lattices. The transition is treated on the lines of the Bragg-Williams-Bethe theory as a phase transition of second order in close analogy to the transition observed with Î-brass. Jones and Allen in a recent communication to NATURE2 also referred to this idea. In both these papers, use is made of the fact, established by the present author, that with the absorbed abnormally great molecular volume of liquid helium (caused by the zero motion3) the diamond-configuration has the lowest potential energy among all regular lattice structures4.

• F. LONDON
Letter
• ### Transport Phenomena in Helium II

F. LONDON1 has recently proposed a new conception of helium II, according to which this liquid can be regarded as a degenerate Bose-Einstein gas, that is, as a system in which one fraction of the substance—say, n atoms per cm.3—is distributed over the excited states in a way determined by the temperature, while the rest—n0n atoms per cm.3—is 'condensed' in the lowest energy level. If T0 denotes the temperature of degeneracy, the ratio n/n0 is given by

For an ideal Bose-Einstein gas, according to London, s = 3/2, but for the real fluid one should rather insert s = 5 in order to fit Keesom's specific heat measurements.

• L. TISZA
Research Article
• ### New Phenomena Connected with Heat Flow in Helium II

SINCE publishing the preliminary measurements on thermal conduction in liquid helium II1 which showed a variation of conductivity with temperature gradient, further data have been collected concerning the phenomenon.

• J. F. ALLEN
• H. JONES
Letter
• ### Viscosity of Liquid Helium below the λ-Point

THE abnormally high heat conductivity of helium II below the λ-point, as first observed by Keesom, suggested to me the possibility of an explanation in terms of convection currents. This explanation would require helium II to have an abnormally low viscosity; at present, the only viscosity measurements on liquid helium have been made in Toronto1, and showed that there is a drop in viscosity below the λ-point by a factor of 3 compared with liquid helium at normal pressure, and by a factor of 8 compared with the value just above the λ-point. In these experiments, however, no check was made to ensure that the motion was laminar, and not turbulent.

• P. Kapitza
Letter
• ### Flow of Liquid Helium II

A SURVEY of the various properties of liquid helium II has prompted us to investigate its viscosity more carefully. One of us1 had previously deduced an upper limit of 10−5 C.G.S. units for the viscosity of helium II by measuring the damping of an oscillating cylinder. We had reached the same conclusion as Kapitza in the letter above ; namely, that due to the high Reynolds number involved, the measurements probably represent non-laminar flow.

• J. F. ALLEN
• A. D. MISENER
Letter
• ### Artificial Production of Fast Protons

A HIGH potential laboratory has been developed at the Cavendish Laboratory for the study of the properties of high speed positive ions. The potential from a high voltage transformer is rectified and multiplied four times by a special arrangement of rectifiers and condensers, giving a working steady potential of 800 kilovolts. Currents of the order of a milliampere may be obtained at a potential constant to 1–2 per cent.

• J. D. COCKCROFT
• E. T. S. WALTON
Letter
• ### Disintegration of Lithium by Swift Protons

IN a previous letter to this journal1 we have described a method of producing a steady stream of swift protons of energies up to 600 kilovolts by the application of high potentials, and have described experiments to measure the range of travel of these protons outside the tube. We have employed the same method to examine the effect of the bombardment of a layer of lithium by a stream of these ions, the lithium being placed inside the tube at 45° to the beam. A mica window of stopping power of 2 cm. of air was sealed on to the side of the tube, and the existence of radiation from the lithium was investigated by the scintillation method outside the tube. The thickness of the mica window was much more than sufficient to prevent any scattered protons from escaping into the air even at the highest voltages used.

• J. D. COCKCROFT
• E. T. S. WALTON
Letter
• ### C60: Buckminsterfullerene

During experiments aimed at understanding the mechanisms by which long-chain carbon molecules are formed in interstellar space and circumstellar shells1, graphite has been vaporized by laser irradiation, producing a remarkably stable cluster consisting of 60 carbon atoms. Concerning the question of what kind of 60-carbon atom structure might give rise to a superstable species, we suggest a truncated icosahedron, a polygon with 60 vertices and 32 faces, 12 of which are pentagonal and 20 hexagonal. This object is commonly encountered as the football shown in Fig. 1. The C60 molecule which results when a carbon atom is placed at each vertex of this structure has all valences satisfied by two single bonds and one double bond, has many resonance structures, and appears to be aromatic.

• H. W. Kroto
• J. R. Heath
• R. E. Smalley
Letter
• ### Disintegration of Uranium by Neutrons: a New Type of Nuclear Reaction

ON bombarding uranium with neutrons, Fermi and collaborators1 found that at least four radioactive substances were produced, to two of which atomic numbers larger than 92 were ascribed. Further investigations2 demonstrated the existence of at least nine radioactive periods, six of which were assigned to elements beyond uranium, and nuclear isomerism had to be assumed in order to account for their chemical behaviour together with their genetic relations.

• Lise Meitner
• O. R. Frisch
Letter
• ### The Scattering of Electrons by a Single Crystal of Nickel

IN a series of experiments now in progress, we are directing a narrow beam of electrons normally against a target cut from a single crystal of nickel, and are measuring the intensity of scattering (number of electrons per unit solid angle with speeds near that of the bombarding electrons) in various directions in front of the target. The experimental arrangement is such that the intensity of scattering can be measured in any latitude from the equator (plane of the target) to within 20° of the pole (incident beam) and in any azimuth.

• C. Davisson
• L. H. Germer
Letter
• ### Observation of a Rapidly Pulsating Radio Source

Unusual signals from pulsating radio sources have been recorded at the Mullard Radio Astronomy Observatory. The radiation seems to come from local objects within the galaxy, and may be associated with oscillations of white dwarf or neutron stars.

• A. HEWISH
• S. J. BELL
• R. A. COLLINS
Article
• ### Waves and Quanta

THE quantum relation, energy = h × frequency, leads one to associate a periodical phenomenon with any isolated portion of matter or energy. An observer bound to the portion of matter will associate with it a frequency determined by its internal energy, namely, by its “mass at rest.” An observer for whom a portion of matter is in steady motion with velocity c, will see this frequency lower in consequence of the Lorentz-Einstein time transformation. I have been able to show (Comptes rendus, September 10 and 24, of the Paris Academy of Sciences) that the fixed observer will constantly see the internal periodical phenomenon in phase with a wave the frequency of which is determined by the quantum relation using the whole energy of the moving body—provided it is assumed that the wave spreads with the velocity c/. This wave, the velocity of which is greater than c, cannot carry energy.

• LOUIS DE BROGLIE
Letter
• ### A New Type of Secondary Radiation

IF we assume that the X-ray scattering of the ‘unmodified’ type observed by Prof. Compton corresponds to the normal or average state of the atoms and molecules, while the ‘modified’ scattering of altered wave-length corresponds to their fluctuations from that state, it would follow that we should expect also in the case of ordinary light two types of scattering, one determined by the normal optical properties of the atoms or molecules, and another representing the effect of their fluctuations from their normal state. It accordingly becomes necessary to test whether this is actually the case. The experiments we have made have confirmed this anticipation, and shown that in every case in which light is scattered by the molecules in dust-free liquids or gases, the diffuse radiation of the ordinary kind, having the same wave-length as the incident beam, is accompanied by a modified scattered radiation of degraded frequency.

• C. V. RAMAN
• K. S. KRISHNAN
Letter
• ### Image Formation by Induced Local Interactions: Examples Employing Nuclear Magnetic Resonance

AN image of an object may be defined as a graphical representation of the spatial distribution of one or more of its properties. Image formation usually requires that the object interact with a matter or radiation field characterized by a wavelength comparable to or smaller than the smallest features to be distinguished, so that the region of interaction may be restricted and a resolved image generated.

• P. C. LAUTERBUR
Letter
• ### Evidence for the Existence of New Unstable Elementary Particles

AMONG some fifty counter-controlled cloud-chamber photographs of penetrating showers which we have obtained during the past year as part of an investigation of the nature of penetrating particles occurring in cosmic ray showers under lead, there are two photographs containing forked tracks of a very striking character. These photographs have been selected from five thousand photographs taken in an effective time of operation of 1,500 hours. On the basis of the analysis given below we believe that one of the fonked tracks, shown in Fig. 1 (tracks a and b), represents the spontaneous transformation in the gas of the chamber of a new type of uncharged elementary particle into lighter charged particles, and that the other, shown in Fig. 2 (tracks a and b), represents similarly the transformation of a new type of charged particle into two light particles, one of which is charged and the other uncharged.

• G. D. ROCHESTERDr.
• C. C. BUTLERDr.
Article
• ### Stimulated Optical Radiation in Ruby

Schawlow and Townes1 have proposed a technique for the generation of very monochromatic radiation in the infra-red optical region of the spectrum using an alkali vapour as the active medium. Javan2 and Sanders3 have discussed proposals involving electron-excited gaseous systems. In this laboratory an optical pumping technique has been successfully applied to a fluorescent solid resulting in the attainment of negative temperatures and stimulated optical emission at a wave-length of 6943 Å. ; the active material used was ruby (chromium in corundum).

• T. H. MAIMAN
Letter
• ### Possible Existence of a Neutron

IT has been shown by Bothe and others that beryllium when bombarded by α-particles of polonium emits a radiation of great penetrating power, which has an absorption coefficient in lead of about 0.3 (cm.)−-1. Recently Mme. Curie-Joliot and M. Joliot found, when measuring the ionisation produced by this beryllium radiation in a vessel with a thin window, that the ionisation increased when matter containing hydrogen was placed in front of the window. The effect appeared to be due to the ejection of protons with velocities up to a maximum of nearly 3 × 109 cm. per sec. They suggested that the transference of energy to the proton was by a process similar to the Compton effect, and estimated that the beryllium radiation had a quantum energy of 50 × 106 electron volts.

Letter
• ### Superconductivity above 130 K in the Hg–Ba–Ca–Cu–O system

THE recent discovery1 of superconductivity below a transition temperature (Tc) of 94 K in HgBa2CuO4+δ has extended the repertoire of high-Tc superconductors containing copper oxide planes embedded in suitably structured (layered) materials. Previous experience with similar compounds containing bismuth and thallium instead of mercury suggested that even higher transition temperatures might be achieved in mercury-based compounds with more than one CuO2 layer per unit cell. Here we provide support for this conjecture, with the discovery of superconductivity above 130 K in a material containing HgBa2Ca2Cu3O1+x (with three CuO2 layers per unit cell), HgBa2CaCu2O6+x (with two CuO2 layers) and an ordered superstructure comprising a defined sequence of the unit cells of these phases. Both magnetic and resistivity measurements confirm a maximum transition temperature of ∼ 133 K, distinctly higher than the previous established record value of 125–127 K observed in Tl2Ba2Ca2Cu3O10 (refs 2,3).

• A. Schilling
• M. Cantoni
• H. R. Ott
Letter
• ### On a New Kind of Rays

(1) A DISCHARGE from a large induction coil is passed through a Hittorf's vacuum tube, or through a well-exhausted Crookes' or Lenard's tube. The tube is surrounded by a fairly close-fitting shield of black paper; it is then possible to see, in a completely darkened room, that paper covered on one side with barium platino-cyanide lights up with brilliant fluorescence when brought into the neighbourhood of the tube, whether the painted side or the other be turned towards the tube. The fluorescence is still visible at two metres distance. It is easy to show that the origin of the fluorescence lies within the vacuum tube.

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