The structures of space and time associated with various four-dimensional symmetries are constructed and examined. It is interesting that some of these four-dimensional symmetries are compatible with the existence of an aether in the Einstein sense. There are two classes of infinitely many four-dimensional symmetries that cannot be ruled out by previous experiments. We discuss some laser experiments that test these two classes of four-dimensional symmetries. An interesting connection between the nonclassical aether and gravity through the equality of inertial (...) and gravitational mass is explored. (shrink)

Transoral laser microsurgery applies to the piecemeal removal of malignant tumours of the upper aerodigestive tract using the CO2 laser under the operating microscope. This method of surgery is being increasingly popularised as a single modality treatment of choice in early laryngeal cancers (T1 and T2) and occasionally in the more advanced forms of the disease (T3 and T4), predomi- nantly within the supraglottis. Thomas Kuhn, the American physicist turned philosopher and historian of science, coined the phrase ‘paradigm (...) shift’ in his groundbreaking book The Structure of Scientific Revolutions. He argued that the arrival of the new and often incompatible idea forms the core of a new paradigm, the birth of an entirely new way of thinking. This article discusses whether Steiner and col- leagues truly brought about a paradigm shift in oncological surgery. By rejecting the principle of en block resection and by replacing it with the belief that not only is it oncologically safe to cut through the substance of the tumour but in doing so one can actually achieve better results, Steiner was able to truly revolutionise the man- agement of laryngeal cancer. Even though within this article the repercussions of his insight are limited to the upper aerodigestive tract oncological surgery, his willingness to question other peoples’ dogma makes his contribution truly a genuine paradigm shift. (shrink)

Optogenetics and DREADDs (Designer Receptors Exclusively Activated by Designer Drugs) are important research tools in recent neurobiology. These tools allow unprecedented control over activity in specifically targeted neurons in behaving animals. Two approaches in philosophy of neuroscience, mechanism and ruthless reductionism, provide explicit accounts of experiments and results using tools like these, but each offers a different picture about how levels of mechanisms relate. I argue here that the ruthless reductionist’s direct mind‐to‐cellular/molecular activities linkages “in a single bound” better fits (...) with both the experimental designs using these tools and some of the scientists’ own judgments about their results than does the mechanist’s “nested hierarchies of mechanisms‐within‐mechanisms.” So at least some important work in current neuroscience appears to be ruthlessly reductive. Mechanism may not correctly characterize all current work in neuroscience, despite its recent popularity. (shrink)

The Razor says: do not multiply entities without necessity! The Laser says: do not multiply fundamental entities without necessity! Behind the Laser lies a deep insight. This is a distinction between the costs and the commitments of a theory. According to the Razor, every commitment is a cost. Not so according to the Laser. According to the Laser, derivative entities are an ontological free lunch: that is, they are a commitment without a cost. Jonathan Schaffer (2015) (...) has argued that the Laser should replace the Razor. In Sections 2-4 we shall discuss and argue against Schaffer’s arguments for replacing the Razor with the Laser. Schaffer considers several objections to his views, and in Sections 5-7 we shall argue that Schaffer does not deal successfully with two of them. In Section 8 we shall present a probabilistic argument for the Laser. However, the argument has a limitation and does not support the replacement of the Razor with the Laser. Indeed, it supports only the claim that, given certain assumptions, the multiplication of explanatorily relevant derivative entities does not matter; but, as we argue in the same section, there is an argument that multiplying explanatorily superfluous derivative entities does makes a theory less rationally acceptable. Our conclusion is that the Laser cannot replace the Razor and that derivative entities are not an ontological free lunch. (shrink)

The laser, first operated in 1960, produced light with coherence properties that demanded explanation. While some attempted a treatment within the framework of classical coherence theory, others insisted that only quantum electrodynamics could give adequate insight and generality. The result was a sharp and rather bitter controversy, conducted over the physics and mathematics that were being deployed, but also over the criteria for doing good science. Three physicists were at the center of this dispute, Emil Wolf, Max Born’s collaborator (...) on a canonical text on optics as a branch of classical electromagnetism, Roy J. Glauber, a student of Julian Schwinger and a high-energy particle theorist, and Leonard Mandel, both experimentalist and theorist and versed in the physics of photodetection. The story told here is thus one of three distinct research trajectories and of the explosion that occurred when, pushed into the well-financed field of laser studies, these trajectories collided. (shrink)

But there may be another way. Laser powered launching to orbit is an emerging space technology that may eventually provide a techno-fix for the large expense of getting payloads into orbit, a way around the high cost of Shuttle payloads. Extremely powerful lasers are now on the hi-tech horizon, and their development promises to make this new technology feasible. In July of 1986 a group of experts gathered at Lawrence Livermore National Laboratory to consider the key issues of (...) class='Hi'>laser propulsion. They focused on three basic questions: (1) What laser launching will be possible with the big lasers now under development? (2) What groundwork of research and development is needed to prepare for launch testing when the big lasers are ready? And (3) What characteristics should be pushed for in these big lasers so that they will be more useful for such launching? This Alternate View column follows some of their discussion. (shrink)

Reflectance physicalism only provides a partial picture of the ontology of color. Byrne & Hilbert’ account is unsatisfactory because the replacement of reflectance functions by productance functions is ad hoc, unclear, and only leads to new problems. Furthermore, the effects of color contrast and differences in illumination are not really taken seriously: Too many “real” colors are tacitly dismissed as illusory, and this for arbitrary reasons. We claim that there cannot be an all-embracing ontology for color.

The mechanism of laser-induced gas ionization is analyzed in the context of the theories presently available, namely multiphoton and cascade theory, and their predictions are shown to be in serious divergence from experimentation. A novel hypothesis is then formulated which considers the classical photon energy expression ε=hν as the limit of a general expression ε=hν/[1−βν f(I)],f(I) being a function of light intensity and βν a coefficient such that βν f(I) significantly differs from zero only for high-intensity laser light. (...) Starting from the new formulation of the photon energy expression, a theory is developed for the laser ionization phenomenon and a few simple relations are found. The successful use of these relations in the verification of the experimental results suggests that the new photon energy expression has a real physical meaning rather than an empirical significance, and some considerations on the physical meaning are presented. (shrink)

Epilepsy surgery is the most effective therapeutic approach for children with drug resistant epilepsy. Recent advances in neurosurgery, such as the Laser Interstitial Thermal Therapy, improved the safety and non-invasiveness of this method. Electric and magnetic source imaging plays critical role in the delineation of the epileptogenic focus during the presurgical evaluation of children with DRE. Yet, they are currently underutilized even in tertiary epilepsy centers. Here, we present a case of an adolescent who suffered from DRE for 16 (...) years and underwent surgery at Cook Children's Medical Center. The patient was previously evaluated in a level 4 epilepsy center and treated with multiple antiseizure medications for several years. Presurgical evaluation at CCMC included long-term video electroencephalography, magnetoencephalography with simultaneous conventional EEG and high-density EEG in two consecutive sessions, MRI, and fluorodeoxyglucose - positron emission tomography. Video long-term EEG captured nine focal-onset clinical seizures with a maximal evolution over the right frontal/frontal midline areas. MRI was initially interpreted as non-lesional. FDG-PET revealed a small region of hypometabolism at the anterior right superior temporal gyrus. ESI and MSI performed with dipole clustering showed a tight cluster of dipoles in the right anterior insula. The patient underwent intracranial EEG which indicated the right anterior insular as seizure onset zone. Eventually LITT rendered the patient seizure free. Retrospective analysis of ESI and MSI clustered dipoles found a mean distance of dipoles from the ablated volume ranging from 10 to 25 mm. Our findings highlight the importance of recent technological advances in the presurgical evaluation and surgical treatment of children with DRE, and the underutilization of epilepsy surgery in children with DRE. (shrink)

Principles of Laser Spectroscopy and Quantum Optics is an essential textbook for graduate students studying the interaction of optical fields with atoms. It also serves as an ideal reference text for researchers working in the fields of laser spectroscopy and quantum optics. The book provides a rigorous introduction to the prototypical problems of radiation fields interacting with two- and three-level atomic systems. It examines the interaction of radiation with both atomic vapors and condensed matter systems, the density matrix (...) and the Bloch vector, and applications involving linear absorption and saturation spectroscopy. Other topics include hole burning, dark states, slow light, and coherent transient spectroscopy, as well as atom optics and atom interferometry. In the second half of the text, the authors consider applications in which the radiation field is quantized. Topics include spontaneous decay, optical pumping, sub-Doppler laser cooling, the Heisenberg equations of motion for atomic and field operators, and light scattering by atoms in both weak and strong external fields. The concluding chapter offers methods for creating entangled and spin-squeezed states of matter. Instructors can create a one-semester course based on this book by combining the introductory chapters with a selection of the more advanced material. A solutions manual is available to teachers. Rigorous introduction to the interaction of optical fields with atoms Applications include linear and nonlinear spectroscopy, dark states, and slow light Extensive chapter on atom optics and atom interferometry Conclusion explores entangled and spin-squeezed states of matter Solutions manual. (shrink)

The words "atom laser" appearing in a science fiction magazine conjure up visions of death rays and space battles. The real device is rather different in its implications and ultimately is much less likely to be a weapon than a tool for probing the innermost secrets of Nature. Therefore, let's begin by reviewing some basic facts about quantum statistics and the ground rules for the operation of lasers.

Light sheet microscopy is an easy to implement and extremely powerful alternative to established fluorescence imaging techniques such as laser scanning confocal, multi‐photon and spinning disk microscopy. By illuminating the sample only with a thin slice of light, photo‐bleaching is reduced to a minimum, making light sheet microscopy ideal for non‐destructive imaging of fragile samples over extended periods of time. Millimeter‐sized samples can be imaged rapidly with high resolution and high depth penetration. A large variety of instruments have been (...) developed and optimized for a number of different samples: Bessel beams form thin light sheets for single cells, and selective plane illumination microscopy (SPIM) offers multi‐view acquisition to image entire embryos with isotropic resolution. This review explains how light sheet microscopy involves a conceptually new microscope design and how it changes modern imaging in biology. (shrink)

Alternate View Column AV-105 Keywords: superluminal faster-than-light laser pulses phase front velocity negative group velocity reshaping Published in the March-2001 issue of Analog Science Fiction & Fact Magazine ; This column was written and submitted 08/19/2000 and is copyrighted ©2000 by John G. Cramer. All rights reserved. No part may be reproduced in any form without the explicit permission of the author.

Ockham’s Razor advises us to not multiply entities without necessity. Recently, Jonathan Schaffer and Karen Bennett have argued that we ought to replace Ockham’s Razor with the Laser, the principle that only advises us to not multiply fundamental entities without necessity. In this paper, I argue that Ockham’s Razor is preferable to the Laser. I begin by contending that the arguments offered for the Laser by Schaffer and Bennett are unpersuasive. Then I offer two cases of theory (...) assessment that I believe the Razor handles better than the Laser. Finally, I argue that accepting the Laser gives rise to a difficult explanatory challenge: It is difficult to explain why fundamental entities and non-fundamental entities ought to be treated differently in ontological parsimony assessments. A recurring secondary theme of the paper is that the most tempting ways of responding to my arguments frequently result in the Laser losing much of its significance for debates about ontology. Thus, not only is it difficult to defend a preference for the Laser over the Razor, but it is especially difficult to do so while maintaining the Laser’s dialectical significance. (shrink)

This paper presents a method of measuring the vibration patterns on facial surfaces by using a scanning laser Doppler vibrometer (LDV). The surfaces of the face, neck, and body vibrate during phonation and, according to Titze ( 2001 ), these vibrations occur when aerodynamic energy is efficiently converted into acoustic energy at the glottis. A vocalist's vibration velocity patterns may therefore indicate his or her phonatory status or singing skills. LDVs enable laser-based non-contact measurement of the vibration velocity (...) and displacement of a certain point on a vibrating object, and scanning LDVs permit multipoint measurements. The benefits of scanning LDVs originate from the facts that they do not affect the vibrations of measured objects and that they can rapidly measure the vibration patterns across planes. A case study is presented herein to demonstrate the method of measuring vibration velocity patterns with a scanning LDV. The objective of the experiment was to measure the vibration velocity differences between the modal and falsetto registers while three professional soprano singers sang sustained vowels at four pitch frequencies. The results suggest that there is a possibility that pitch frequency are correlated with vibration velocity. However, further investigations are necessary to clarify the relationships between vibration velocity patterns and phonation status and singing skills. (shrink)

Innovations in technology and science form novel fields that, although beneficial, introduce new bio-ethical issues. In their short history, lasers have greatly influenced our everyday lives, especially in medicine. This paper focuses particularly on medical and para-medical laser ethics and their origins, and presents the complex relationships within laser ethics through a three-dimensional matrix model. The term ‘laser’ and the myth of the ‘magic light’ can be identified as landmarks for laser related ethical issues. These ethical (...) issues are divided into five major groups: media, marketing, and advertising; economic outcomes; user training; the user-patient/client relationship; and other issues. In addition, issues arising from two of the most common applications of lasers, laser eye surgery and laser tattoo removal, are discussed. The aim of this paper is to demonstrate that the use of medical and para-medical lasers has so greatly influenced our lives that the scientific community must initiate an earnest discussion of medical laser ethics. (shrink)

The discovery of the Higgs boson at LHC confirms that what we experience as empty space should actually be thought as a condensate of elementary quanta. This condensate characterizes the physically realized form of relativity and could play the role of preferred reference frame in a modern Lorentzian approach. This observation suggests a new interpretative scheme to understand the unexplained residuals in the old ether-drift experiments where light was still propagating in gaseous systems. Differently from present vacuum experiments, where anyhow (...) deviations from Special Relativity are expected to be at the limit of visibility, these now acquire a crucial importance and become consistent with the Earth’s velocity of 370 km/s which characterizes the CMB anisotropy. In the same scheme, one can also understand the difference with the other experiments where light propagates in strongly bound systems such as solid or liquid transparent media. This non-trivial level of consistency motivates a new generation of precise laser interferometry experiments which explore the same particle physics vacuum and, in this sense, are complementary to those with high-energy accelerators. (shrink)

One of Nancy Cartwright's arguments for entity realism focuses on the non-redundancy of causal explanation. In How the Laws of Physics Lie she uses an example from laser theory to illustrate how we can have a variety of theoretical treatments governing the same phenomena while allowing just one causal story. In the following I show that in the particular example Cartwright chooses causal explanation exhibits the same kind of redundancy present in theoretical explanation. In an attempt to salvage Cartwright's (...) example the causal explanation could be reinterpreted as a capacity claim, as outlined in her recent work Nature's Capacities and Their Measurement. However, I argue that capacities cannot be isolated in the way that Cartwright suggests and consequently these capacity claims also fail to provide a unique causal story. We can, however, make sense of capacities by characterizing them in a relational way and I offer some ideas as to how this approach would retain our intuitions about capacities while denying their ontological priority as dormant powers. (shrink)

In recent times it has become common to encounter philosophers who recommend the replacement of one principle concerning theory choice, Ockham’s Razor, with another: the Laser. Whilst the Razor tells us not to multiply entities beyond necessity, the Laser tells us only to avoid multiplying fundamental entities beyond necessity. There appear to be seven arguments in the literature for the Laser. They divide into three categories: arguments from the nature of non-fundamentality attempt to motivate the Laser (...) by appeal to various observations about what it is to be non-fundamental; arguments from cases describe hypothetical or actual cases, and allege that only the Laser accords with our intuitive judgements about them; and arguments from analogy claim that ontological parsimony is analogous to conceptual economy, and that this analogy recommends the Laser. I provide novel responses to each of the extant arguments for the Laser, and conclude that there is currently no good reason for replacing the Razor with the Laser. (shrink)

Using the linearized Einstein gravitational field equations and the Maxwell field equations it is shown that the plane of polarization of an electromagnetic wave is rotated by the gravitational field created by the electromagnetic radiation of a ring laser. It is further shown that this gravitational Faraday effect shares many of the properties of the standard electromagnetic Faraday effect. An experimental arrangement is then suggested for the observation of this gravitational Faraday effect induced by the ring laser.

Femtosecond laser microfabrication has emerged in the last decade as a powerful technique for direct inscription of low loss optical waveguides in practically any transparent dielectric substrate, showing outstanding versatility. Prototyping of new devices is made rapid, cheap and easy: optical circuits are written directly buried in the substrate, using the laser beam as an optical pen, without any need of costly masks as required by conventional photolithography. Many proof-of-principle demonstrations of integrated optics can be obtained, including splitters, (...) directional couplers, and Mach–Zehnder interferometers. Actually, the road towards applications has just been opened, and the unique capabilities of femtosecond laser micromachining will enable achievements inconceivable with other technologies. In this work, the femtosecond laser fabrication technique is discussed, together with its application to the realization of integrated photonic quantum circuits. (shrink)

A Λ-type inversionless laser scheme is analyzed in which lasing is achieved under conditions when a conventional or a Raman laser would fail to operate. The dependence of gain on the parameters of the system is studied numerically. A realization in heliumlike ions is proposed which permits laser action at a wavelength of around 6 nm.

The quantum theory of the laser of Scully and Lamb is used to determine the longest-lived states of the quantized field in an idealized, single-mode laser cavity. It is shown that quasiclassical states (states with well-defined phase and amplitude) are naturally selected. A quantum trajectory analysis provides some insight as to why this is so.

The laser chaos decision maker has been demonstrated to enable ultra-high-speed solutions of multiarmed bandit problems or decision-making in the GHz order. However, the underlying mechanisms are not well understood. In this paper, we analyze the chaotic dynamics inherent in experimentally observed laser chaos time series via surrogate data and further accelerate the decision-making performance via parameter optimization. We first evaluate the negative autocorrelation in a chaotic time series and its impact on decision-making detail. Then, we analyze the (...) decision-making ability using three different surrogate chaos time series to examine the underlying mechanism. We clarify that the negative autocorrelation of laser chaos improves decision-making and that the amplitude distribution of the original laser chaos time series is not optimal. Hence, we introduce a new parameter for adjusting the amplitude distribution of the laser chaos to enhance the decision-making performance. This study provides a new insight into exploiting the supremacy of chaotic dynamics in artificially constructed intelligent systems. (shrink)

Recently, a friend of one of these writers told her story of using one of a healthcare product to activate her stem cells as part of regenerative medicine. Regenerative medicine is a field of medicine that seeks to repair or replace damaged or diseased tissues and organs. This can be done through a variety of methods, including stem cell therapy, tissue engineering, and gene therapy. This is a short review article on this rapid field called regenerative medicine, in particular via (...) a new method called photobiomodulation, especially by virtue of low-intensity laser pen treatment. Hopefully it will attract more research in this interesting direction, both for laser/photobiomodulation to boost plant growth as well as in healthcare (see also: Christianto & Smarandache, 2022; Christianto, 2023). (shrink)

One of the most important characteristics of modern science is its replicability and objectivity. This means that a scientific result is taken as such only when it has been reproduced by other scientists. Indeed, the replicability of a scientific result in an objective and independent way by members of a scientific community is the cornerstone of science. Experimental laser physics is an example of “normal” science, where it is no doubt that the phenomenon could be replicated; however, the replication (...) process may not be straightforward since it requires a good understanding of the physics behind it, as well as good technical skills. In this article, two laboratory cases of experiments on laser physics are presented: the first one deals with a Nitrogen N2 laser with a Polloni excitation circuit, and the second one deals with a transversally excited TEA carbon dioxide laser. For the nitrogen laser, it will be shown that reproducibility failed, and therefore, the reported experiment cannot be taken as a valid contribution to the advancement and understanding of nitrogen laser physics and technology. On the other hand, for the case of the TEA carbon dioxide laser, several comments are presented on the development of this finally successful experiment. Both cases show the importance of being technically up-dated in order to reproduce or improve the results reported by other researchers. Finally, a discussion about: What can we learn about the research practice from these two cases? It is presented, as well as the conclusions about the case studies; we hope they may be useful to philosophers of science and young scientists alike. (shrink)

We have compared two different laser-induced optical light traps for their utility in moving organelles within living animal cells and walled fungal cells. The first trap employed a continuous wave neodymium-yttrium aluminum garnet laser at a wavelength of 1.06 micron. A second trap was constructed using a titanium-sapphire laser tunable from 700 to 1000 nm. With the latter trap we were able to achieve much stronger traps with less laser power and without damage to either mitochondria (...) or spindles. Chromosomes and nuclei were easily displaced, nucleoli were separated and moved far away from interphase nuclei, and Woronin bodies were removed from septa. In comparison, these manipulations were not possible with the Nd-YAG laser-induced trap. The optical force trap induced by the tunable titanium-sapphire laser should find wide application in experimental cell biology because the wavelength can be selected for maximization of force production and minimization of energy absorption which leads to unwanted cell damage. (shrink)

We describe a new experiment to measure the gravitomagnetic field of the Earth. This field, a consequence of the general relativistic formulation of Mach's principle (WEM—Wheeler-Einstein-Mach principle), has never been detected. The idea is to measure the Lense-Thirring precession of the nodal lines of two laser-ranged satellites with supplementary inclinations. In this way it is possible to separate the relativistic nodal precession from the classical nodal precession due to the multipole moments of the Earth.

The laser scanning confocal microscope (LSCM)LSCM: laser scanning confocal microscope; FISH: fluorescence in situ hybridisation; DiO6: 3,3′‐dihexyloxacarbocyanine iodide; NBD‐ceramide: 6‐((N‐(7‐nitrobenz‐2‐oxa‐1,3‐diazol‐4‐yl)amino)‐caproyl)sphingosine; DiO: 3,3′‐dioctadecyloxacarbocyanine perchlorate; DiI: 1,1′‐dioctadecyl‐3,3,3′,3′‐tetramethyl‐indocarbocyanine perchlorate; CCD: charge‐coupled device; DIC: differential interference contrast; FURA2: (‐(2‐(5‐carboxyoxazol‐2‐yl)‐6‐aminobenzofuran‐5‐oxy)‐2‐)2′‐amino‐5′‐methylphenoxy)‐ethane‐N,N,N′,N′‐ tetraacetic acid, sodium salt);BCECF: 2′,7′‐bis‐(carboxyethyl)‐5‐(and‐6‐)‐carboxyfluorescein;fluo‐3: 1‐(2‐amino‐5‐(2,7‐dichloro‐6‐hydroxy‐3‐oxo‐3H‐xanthen‐9‐yl)‐2‐(2′amino‐5′‐methylphenoxy)‐ethane‐N,N, N′,N′,‐tetraacetic acid, ammonium salt; DAPI: 4′,6‐diamidino‐2‐phenylindole, dihydrochloride; PET: positron emission tomogrophy; CT: computer‐assisted tomogrophy; CiD: cubitus interruptus dominus; MRC: Medical Research Council; TOTO‐1: benzothiazolium‐4‐quinolinium dimer; YOYO‐1: benzoxazolium‐4‐quinolinium dimer; ex.: excitation wavelength; em.: emission wavelength. is now established as an invaluable (...) tool in developmental biology for improved light microscope imaging of fluorescently labelled eggs, embryos and developing tissues. The universal application of the LSCM in biomedical research has stimulated improvements to the microscopes themselves and the synthesis of novel probes for imaging biological structures and physiological processes. Moreover the ability of the LSCM to produce an optical series in perfect register has made computer 3‐D reconstruction and analysis of light microscope images a practical option. (shrink)

The invention of the laser in 1960 and the innovation process of laser technology during the following years coincided with the dramatic increase of the East-West-conflict during the 1960s – the peak of the so-called Cold War after the erection of the Berlin Wall in 1961. The predictable features of the new device, not only for experimental sciences, but also for technical and military applications, led instantly to a laser hype all over the world. Military funding and (...) research played a major part in this development. Especially in the United States military laser research and development played an important role in the formation of Cold War sciences. The European allies followed this example to a certain degree, but their specific national environments led to quite different solutions and results. This article describes and analyzes the special features and background of this development for the Federal Republic of Germany in the area of conflict between science, politics and industry from 1960 to the early 1970s. (shrink)