zbigniew.modrzejewski

You missed the rest of my post

So, where can we find negative mass? There is no consensus in the physics community if negative mass is even allowed to exist, referring to the so-called positive energy theorem that prohibits negative gravitational masses. Robert Forward was an American science fiction writer. His literary work was noted for its scientific credibility. Robert Forward first pointed out that a gravitational dipole, consisting of ordinary and negative matter, would be self-accelerating thus creating the ultimate propellant-less propulsion system. Up to now, the key ingredient, negative matter, has not been found to exist in natural form. However, since E=mc², negative matter may be created in a laboratory using negative energies. Previous studies showed that effective negative inertia exists for neutrons and also for electrons in short transient time intervals. Let's consider two possibilities to create stationary, charged negative effective masses that could be used to test Robert Forward’s self-propulsion effect. One is based on the assumption that Weber’s electrodynamics is correct predicting a negative mass regime for electrons inside a highly charged dielectric sphere. The other possibility is using asymmetric charge distributions that could be realized using electrets. With proper geometry and charge densities, negative mass regimes are derived which could lead to negative energies many orders of magnitude larger than those obtained from the Casimir effect. Based on these concepts, a negative matter space-drive could be realized in a laboratory environment. From an engineering perspective, maybe the most straight-forward concept is called negative matter propulsion, or diametric space drive. It consists of a pair of masses, one with an ordinary positive and the other one with a negative mass. Although Robert Forward assumes that the negative mass has both a negative gravitational and inertial mass, we can only concentrate on the effect of negative inertia. According to Newton’s second law, the acceleration of a mass is always in the direction of the force that acts on it: F=ma Negative inertia would therefore always accelerate in the opposite direction of the applied force. If both types of masses are now coupled with a spring that tries to attract both masses to each other, it is straight-forward to show that this gravitational (or inertial) dipole is self-accelerating. This self-acceleration propulsion system does not need propellant or energy. It should therefore be able to move at any arbitrary speed, even faster than the speed of light, since no energy is involved. Robert Forward showed in his analysis that negative matter propulsion does not violate the conservation of momentum or energy as negative mass also carries negative momentum and energy and hence the total energy of the self-accelerating dipole is zero -- self-acceleration is its ground state. This argument could be even proven for the case if the amount of negative and positive mass is not equal.

So, what was the physical evidence based on which Bohr put forward his un-scientific speculation regarding model of the atom?

Well, then by your standards it should not have been questioned, nor suspected, nor criticised, becuase it didn't disagree with all scientific evidence at the time!

" So, would you say that a speculation that is in contradiction with some of established science is not a scientific speculation? " If it disagrees with experiment, it's wrong. Could you give me an example? So, why Bohr put forward that un-scientific speculation that disagreed with experiment ???

So, to rephrase my question in a hope for straight answer : Could a speculation about negative mass be a scientific speculation? Or maybe true mainstream scientists do not ever speculate about the possibility of physical existence of negative mass?

Could you give me an example?

It is not my speculation, but yes, there seems to be a mathematical proof of negative mass being possible. It is not my model, but yes, repulsive gravitational interaction is being speculated as a strong possibility. First of all, we are in the "Speculation" topic, so I do not think that in regards to scientific speculation we need any mathematical proof. Does a scientific hypothesis need a mathematical proof. Is there a difference between: scientific speculation and scientific hypothesis ?

I have come across a speculation regarding negative mass. Could it be a scientific speculation? Or, true mainstream scientists do not speculate about the possibility of physical existence of negative mass, because negative mass could imply repulsive gravitational interactions?

So, would you say that a speculation that is in contradiction with some of established science is not a scientific speculation? Is there a difference between: scientific speculation and scientific hypothesis ?

According to GTR, any repulsive gravity, or "anti-gravity", is simply impossible. Would it be scientific enough to speculate that a new, more complete theory of gravity could explain how repulsive gravity interactions can be possible?

So, is it possible for a real valid scientific speculation to speculate that GTR may not be the "last word" on gravity, and that there could be a better theory of gravity? What is the "overlap" between quantum physics and GTR?

I would like to know what is the difference between: 1. scientific speculations, and 2. pseudo-speculations as it relates to this topic -- "Speculations", and the "Trash Can" topic. Thank you.

Until now, there have been only two working electromagnetic drive prototypes. The first one, EmDrive, was experimentally verified by NASA. Roger Shawyer opens up about the story behind invention of his EmDrive in an exclusive interview with IBTimes UK. The second one is Guido Fetta's Cannae Drive. And there will be many, many more to come. The new era of economic and affordable electromagnetic near-Light-speed space propulsion has barely began, just like the era of electric cars and electric airplanes. There is only one thing more powerful and explosive than all the armies in the world, and that is an idea whose time has come. Victor Hugo My implementation of the electromagnetic space drive concept is much different from the two above. It is much more powerful, because it takes advantage, among other things, of some aspects of the EinsteinCartan theory in conjunction with the Einstein-deHaas effect, the Biefeld-Brown effect, and some empirical implications of Abraham-Minkowski equations : Link deleted by mod

A Debate Over the Physics of Time https://www.quantama...-and-cosmology/ " Many physicists argue that Einstein’s position is implied by the two pillars of modern physics: Einstein’s masterpiece, the general theory of relativity, and the Standard Model of particle physics. The laws that underlie these theories are time-symmetric — that is, the physics they describe is the same, regardless of whether the variable called “time” increases or decreases. Moreover, they say nothing at all about the point we call “now” — a special moment (or so it appears) for us, but seemingly undefined when we talk about the universe at large. The resulting timeless cosmos is sometimes called a “block universe” — a static block of space-time in which any flow of time, or passage through it, must presumably be a mental construct or other illusion. " What if time is only an illusion? What if it doesn't actually exist? Palle Yourgrau, a Brandeis professor of philosophy, explains that Einstein's general theory of relativity may allow for this possibility. It was first realized by the great logician Kurt Godel in a typically brief paper written for a Festschrift to honor his friend and Princeton neighbor Einstein. Godel is best known for his incompleteness theorem, one of the most important theorems in mathematical logic since Euclid. Palle Yourgrau writes that Godel's paper was almost universally ignored, and he claims that since the logician's death, philosophers have gone out of their way to try to denigrate his work in fields other than logic. In 1942, the logician Kurt Godel suffered a major episode of depression that required a stay at a mental hospital. Upon his release, Albert Einstein, his colleague at the Institute for Advanced Studies, took Godel under his wing and, to cheer him up, gave him "relativity lessons." The two became close friends; they walked to and from their offices at the Institute every day, exchanging ideas about science, philosophy, politics and the lost world of German science in which both men had grown up. By 1949, Godel had produced a remarkable proof: In any universe described by the Theory of Relativity, time cannot exist. Einstein endorsed this result – reluctantly, since it decisively overthrew the classical world-view to which he was committed. But he could find no way to refute it, and in the half-century since then, neither has anyone else. Even more remarkable than this stunning discovery by two of the greatest intellects of all time, however, was what happened afterward: nothing. Cosmologists have proceeded with their work as if time were the linear phenomenon familiar to Newton or Galileo (with some allowances for relativistic distortion); philosophers have refused to recognize Godel as an important philosopher of time. While arguing that these failures constitute major scandals of modern intellectual history, Palle Yourgrau also offers a mitigating explanation. Godel's cosmological findings, he says, are so advanced as to be beyond the ability of modern science to deal with them. A World without Time is a sweeping, ambitious book, and yet poignant and intimate – it tells the story of two magnificent minds put on the shelf by the scientific fashions of their day, and attempts to rescue from undeserved obscurity the brilliant work they did together.

Well, of course, you can call it a "temporal dimension", which does not change the fact that it is essentially a spatial dimension. I will find you a source to verify my statement that according to GTR, time is space.

So, why are you so certain that my hypothesis can not possibly be true ??

According to GTR, time is space — i.e. the 4th static, spatial dimension of spacetime — so how exactly do ticking clocks measure static space .... ?! Can clocks empirically detect the physical existence of time? If not, then they can NOT measure it either. So, what do you all want from me, then ?

And, I am waiting for you to tell me that the unification of gravity and electromagnetism is impossible, because such unification could be a physical basis for the existence of ANTIGRAVITY — Antigravity and classical solutions of five-dimensional Kaluza-Klein theory : https://www.researchgate.net/publication/241520428_Antigravity_and_classical_solutions_of_five-dimensional_Kaluza-Klein_theory

In order to unify the gravitational and electromagnetic fields, Einstein, et al., applied various geometrical structures and theoretical schemes, for example, the gauge invariance geometry, the five-dimensional space-time, the projective theory, the affine field and the bivector fields, etc. The non-symmetric field is the logically simplest relativistic field theory which is at all possible. Hlavaty made the summary and development. Johnson expounded systematically his viewpoints. Gaffney and Moffat, Boal obtained some conclusions and solutions. The unified field theories of more than four-dimensions were summarized. Madore proposed a modification of the traditional formulation of Kaluza-Klein theory in which the internal structure is described by a noncommutative geometry based on a semisimple algebra. The classical theory of Yang-Mills fields and of Dirac fermions is developed in the resulting geometry. The generalized connection is written down which should describe the unification of the Yang-Mills fields with gravity. Moreover, the unification is connected with the string model and the grand unification theory, and the supersymmetry and supergravity, etc. But, because the unified field theory is a very complex and difficult question, further approach should be made still. Recently, the unification of quantum field theory and general relativity as a fundamental goal of modern physics is discussed : https://arxiv.org/ftp/arxiv/papers/0901/0901.0201.pdf Principles of Maxwell, Lorentz, Milne, Dirac and Feynman are combined to unify gravity with electromagnetism. Special-relativistic settled reality (SR) evolves, as universe age increases, via cosmological Feynman paths. Although SR is ‘classical’, its evolution is ‘quantum mechanical’. A unitary Hilbert-space Lorentz-group representation--a lightlike-fiber-bundle— allows definition of divergenceless Lorentz-tensor self-adjoint retarded-potential operators. Feynman-path action (real but not SR) is invariant under a 7-parameter group that augments 6- parameter SL(2,c) by a 1-parameter compact (Kaluza-Klein) group generated by discrete electric charge. Sublightlike charged-particulate matter (a component of ‘objective reality’) reflects ‘zitterbewegung’—fluctuation of a lightlike-velocity direction specified by 2 angles of a 3-sphere fiber. The third fiber angle is Dirac conjugate to a discrete-spectrum electric-charge operator, whose commutation with all potential operators renders discrete the spatially-localized temporally-stable charged-particle component of SR : https://arxiv.org/ftp/arxiv/papers/0901/0901.0201.pdf

In 1992, E. Podkletnov and R. Nieminen found that, under certain conditions, ceramic superconductor with composite structure has revealed weak shielding properties against gravitational force. In classical Newton's theory of gravity and even in Einstein's general theory of gravity, there are no grounds of gravitational shielding effects. But in quantum gauge theory of gravity, the gravitational shielding effects can be explained in a simple and natural way. In quantum gauge theory of gravity, gravitational gauge interactions of complex scalar field can be formulated based on gauge principle. After spontaneous symmetry breaking, if the vacuum of the complex scalar field is not stable and uniform, there will be a mass term of gravitational gauge field. When gravitational gauge field propagates in this unstable vacuum of the complex scalar field, it will decay exponentially, which is the nature of gravitational shielding effects. The mechanism of gravitational shielding effects is studied in this paper, and some main properties of gravitational shielding effects are discussed : arxiv.org/pdf/hep-th/0307225v1.pdf E. Podkletnov, R. Nieminen Physica C, Volume 203, Issues 3–4, 10 December 1992, Pages 441-444 Shielding properties of single-phase dense bulk superconducting ceramics of YBa2Cu3O7−x against the gravitational force were studied at temperatures below 77 K. A small non-conducting and non-magnetic sample weighing 5.48 g was placed over a levitating superconducting disk and the loss of weight was measured with high precision using an electrooptical balance system. The sample was found to lose from 0.05 to 0.3% of its weight, depending on the rotation speed of the superconducting disk. Partial loss of weight might be the result of a certain state of energy which exists inside the crystal structure of the superconductor at low temperatures. The unusual state of energy might have changed a regular interaction between electromagnetic, nuclear and gravitational forces inside a solid body and is responsible for the gravity shielding effect : www.sciencedirect.com/science/article/pii/092145349290055H Theoretical Analysis of a Reported Weak Gravitational Shielding Effect Max-Planck-Institut fur Physik Werner-Heisenberg-Institut Munchen, Germany Under special conditions (Meissner-effect levitation in a high frequency magnetic field and rapid rotation) a disk of high-Tc superconducting material has recently been found to produce a weak shielding of the gravitational field. We show that this phenomenon has no explanation in the standard gravity theories : http://arxiv.org/pdf...-th/9505094.pdf

I would like to point out that there is a subtle difference between "measurement" and "detection". For example, a compass detects the physical existence and orientation of magnetic field, but do not measure its intensity. It would seem that a device that measures some physical quantity must in principle, first of all, also be able to detect physical existence of such quantity. So, to clarify my point, I would like to focus on empirical detection, instead of measurement. If you say that a ruler measures length of space, then does it measure centimeters or inches? What space is fundamentally composed of ? Is there an elementary particle of space to be measured? And now .... Can we empirically detect the physical existence of elementary particles of space? Can we empirically detect the physical existence of dimensions of space? If they exist in reality, which way do they point? Is there a Dimension-counter that we could insert into space, and it will display a number of dimensions present? Just because it seems to us that space is 3D, it is not a scientific proof yet. Would elementary particles of space have mass, energy? If so, could we transform energy of a mass into extra space, maybe?

If a ticking clock "measures" time, does that imply that time passes? If the flow of time were making the clock move, like above, then I would agree that clock really measures the velocity of time flow, or empirically detects its physical existence. However, the physical reason that clocks move (tick) is not that some physical time flows through them, so clocks neither detect nor measure anything other than themselves, I am afraid .... WHAT IS THE REASON THAT CLOCKS STOP ? CLOCKS ONLY STOP MEASURING TIME, WHEN TIME STOPS !!! What if time is only an illusion? What if it doesn't actually exist? Palle Yourgrau, a Brandeis professor of philosophy, explains that Einstein's general theory of relativity may allow for this possibility. It was first realized by the great logician Kurt Godel in a typically brief paper written for a Festschrift to honor his friend and Princeton neighbor Einstein. Godel is best known for his incompleteness theorem, one of the most important theorems in mathematical logic since Euclid. Palle Yourgrau writes that Godel's paper was almost universally ignored, and he claims that since the logician's death, philosophers have gone out of their way to try to denigrate his work in fields other than logic. In 1942, the logician Kurt Godel suffered a major episode of depression that required a stay at a mental hospital. Upon his release, Albert Einstein, his colleague at the Institute for Advanced Studies, took Godel under his wing and, to cheer him up, gave him "relativity lessons." The two became close friends; they walked to and from their offices at the Institute every day, exchanging ideas about science, philosophy, politics and the lost world of German science in which both men had grown up. By 1949, Godel had produced a remarkable proof: In any universe described by the Theory of Relativity, time cannot exist. Einstein endorsed this result – reluctantly, since it decisively overthrew the classical world-view to which he was committed. But he could find no way to refute it, and in the half-century since then, neither has anyone else. Even more remarkable than this stunning discovery by two of the greatest intellects of all time, however, was what happened afterward: nothing. Cosmologists have proceeded with their work as if time were the linear phenomenon familiar to Newton or Galileo (with some allowances for relativistic distortion); philosophers have refused to recognize Godel as an important philosopher of time. While arguing that these failures constitute major scandals of modern intellectual history, Palle Yourgrau also offers a mitigating explanation. Godel's cosmological findings, he says, are so advanced as to be beyond the ability of modern science to deal with them. A World without Time is a sweeping, ambitious book, and yet poignant and intimate – it tells the story of two magnificent minds put on the shelf by the scientific fashions of their day, and attempts to rescue from undeserved obscurity the brilliant work they did together.

Theoretical Analysis of a Reported Weak Gravitational Shielding Effect: http://arxiv.org/pdf/hep-th/9505094.pdf In 1992, E. Podkletnov and R. Nieminen found that, under certain conditions, ceramic superconductor with composite structure has revealed weak shielding properties against gravitational force. In classical Newton's theory of gravity and even in Einstein's general theory of gravity, there are no grounds of gravitational shielding effects. But in quantum gauge theory of gravity, the gravitational shielding effects can be explained in a simple and natural way. In quantum gauge theory of gravity, gravitational gauge interactions of complex scalar field can be formulated based on gauge principle. After spontaneous symmetry breaking, if the vacuum of the complex scalar field is not stable and uniform, there will be a mass term of gravitational gauge field. When gravitational gauge field propagates in this unstable vacuum of the complex scalar field, it will decay exponentially, which is the nature of gravitational shielding effects. The mechanism of gravitational shielding effects is studied in this paper, and some main properties of gravitational shielding effects are discussed: arxiv.org/pdf/hep-th/0307225v1.pdf E. Podkletnov, R. Nieminen Physica C, Volume 203, Issues 3–4, 10 December 1992, Pages 441-444 Shielding properties of single-phase dense bulk superconducting ceramics of YBa2Cu3O7−x against the gravitational force were studied at temperatures below 77 K. A small non-conducting and non-magnetic sample weighing 5.48 g was placed over a levitating superconducting disk and the loss of weight was measured with high precision using an electro-optical balance system. The sample was found to lose from 0.05 to 0.3% of its weight, depending on the rotation speed of the superconducting disk. Partial loss of weight might be the result of a certain state of energy which exists inside the crystal structure of the superconductor at low temperatures. The unusual state of energy might have changed a regular interaction between electromagnetic, nuclear and gravitational forces inside a solid body and is responsible for the gravity shielding effect: www.sciencedirect.com/science/article/pii/092145349290055H Gravitational Field Generation:http://www.e-catworld.com/2015/12/16/gravitational-field-generation-a-third-possible-contender-in-new-physics-for-energy-generation-gregory-daigle/comment-page-1/ Artificial Gravitational Field Generated in the Laboratory: http://www.hpcc-space.com/publications/documents/ArtificialGravity.pdf Based on theoretical ideas under development since 2002, termed the (8-dimensional) Extended (Burkhard) Heim Theory (EHT), as well as experiments performed at AIT Seibersdorf, Austria since 2006, it is argued that there is evidence for the existence of novel gravity-like fields and thus also different types of matter. These gravity-like fields are not described by conventional Newtonian (Einsteinian) gravitation, i.e., by the accumulation of mass. Instead, under certain conditions, they should be producible in the laboratory by small ring or disk shaped masses rotating at cryogenic temperatures. EHT, in describing these novel fields, postulates six fundamental physical interactions, three of them of gravitational nature. The two additional gravity-like fields may be both attractive and repulsive. It is further argued, based on both EHT and experiments, that these gravity-like fields are outside the known four physical fundamental forces, and may result from the conversion of electromagnetic into gravitational fields. The gravitomagnetic effect of these fields is found to be some 18 orders of magnitude larger than classical frame dragging of General Relativity. This fact seems to be in accordance with recent experiments performed at AIT Seibersdorf. A non relativistic semiclassical model will be presented as an attempt to explain the physical nature of the novel gravity-like fields. There seems to be a special phase transition, triggered at cryogenic temperatures, responsible for the conversion of electromagnetic into gravitational fields. The features of the six fundamental physical interactions are utilized to investigate the potential of the novel gravity-like fields for propulsion purposes, as well as energy generation. http://www.hpcc-space.com/publications/documents/GravitySuperconductorsForewordChap11.pdf It is our pleasure to write the Foreword for Gravity-Superconductors Interactions, the first book to further its goal of presenting to the scientific community the state of theoretical and experimental research concerning the latest results in the emerging field of physics for novel gravity-like fields that might represent a new paradigm shift regarding the very nature of gravitation. New theoretical attempts along with experimental work are presented in this book to continue where Einstein was forced to leave off. The quantization of the gravitational field has been unsuccessful, despite great efforts in this direction. The problem may be that the number of fundamental forces is not known, in other words, there is a belief that only four forces exist (strong, weak, electromagnetic, and gravitational force). Perhaps gravity is of a more subtle nature than Newtonian gravity, and an interaction between gravity and electromagnetism might exist? At least, the Maxwell equations of electrodynamics and the linearized Einstein field equations, termed Einstein-Maxwell equations, show surprising structural similarity. New gravitational experiments have been published since 2006, and geometrical theories from the 1950s (for instance, by Finzi, Heim, Wheeler) were extended and combined with concepts of modern physics (symmetry, symmetry breaking, London equations, Ginzburg-Landau theory, spacetime as a physical field, etc.) and have gained some prominence, trying to explain novel experimental results for extreme gravitomagnetic and gravity-like fields. In his monograph on Quantum Field Theory, M. Kaku presents a calculation of the Coleman-Weinberg potential that might be employed to calculate the coupling strength for the extreme gravitomagnetic fields. Most recently, as pointed out by A. Zee in Quantum Field Theory in a Nutshell, gravity might be the square of two spin 1 fields (it should be noted that particles of spin 1 can be described by Yang-Mills fields), an idea that also might be applicable in the explanation of the experiments on extreme gravitomagnetic fields that are 18 orders of magnitude larger than those predicted by general relativity, and, if confirmed, are outside general relativity. These and other exciting ideas are presented here to the reader, and might shed new light on the nature of gravity as well as the number and type of fundamental forces that exist in Nature. Novel theories on the geometrization of physics should provide new statements and propositions that unmistakably should lead to recognizable facts, which should, for instance, occur from the existence of extreme gravitomagnetic and gravity-like fields observed at cryogenic temperatures, rather than by speculation or chance. As Einstein felt, the most important objective of any theory is to comprise as few and basic elements as possible without contradicting physical experience in conjunction with practical applications. For example, as presented in this text, a relationship between the different phenomena of electromagnetism and gravitation might have been discovered. Any novel theory must be verifiable by laboratory experiments or astronomical observations. In order to verify a theory, it must provide a procedure on how the measurable information can be extracted. Since experiments do not produce physical principles, any novel theory must produce meaningful forecasts and also be falsifiable. According to Dirac's dictum: a special regulator of a theory that reflects quality is its beauty. Einstein's theory of general relativity is an example of such a theory. The successful geometrization of physics combined with proper symmetries (group theory) would fit this picture as would the experimental generation of gravity-like fields at cryogenic temperatures by symmetry breaking. In this book, these two important topics are addressed and discussed from various points of view. Needless to say, beauty cannot be the sole yardstick for the correctness of a theory or physical phenomenon, and there is always the danger that, for instance, physical models are invented to fit an experimental situation. An example to be remembered are the (non-existing?!) gravitational waves measured by Weber. It is of utmost importance that any discovery is verified by other laboratories before it can be claimed as valid. Verifying gravitational experiments is not an easy endeavour since highly sensitive devices have to be produced and utilized at cryogenic temperatures, often at liquid Helium temperature. Even if experimental findings or theories eventually cannot be verified, one should not denounce the serious experimenter or theorist for failure, since the history of science has shown that every step forward is a complicated venture, needless to say that all programs for novel theoretical models initially contain many unclear points. But this is true even for established theories. The theory of general relativity has unified gravity with inertia. The equation of motion is for material points moving along geodesics. General relativity interprets gravitation in terms of curvature of spacetime that is, the homogeneity and isotropy of spacetime are violated. Energy and momentum conservation are valid only in flat spacetime, Since gravitational waves require the full nonlinear Einstein field equations, the superposition principle does not seem to hold, in contrast to electromagnetic waves. This would be true only in the weak field limit. Recently, a number of important and interesting experimental results on gravitomagnetic and gravity-like fields, generated in the laboratory, have been obtained. Gravitational experiments are notoriously difficult as can be seen from the fact that the physics of gravitational wave astronomy, despite the early efforts of J. Weber starting out in 1969, is still not an established fact. As was pointed out by the well known theoretical physicist Richard P. Feynman in his now famous lecture, There's Plenty of Room at the Bottom, given already in 1960, and published in the journal Engineering and Science (February 1960), there occur numerous strange phenomena in the complex situations of solid state physics. He prophetically foresaw an enormous number of technical applications that could arise from such physics. He also mentioned Kammerling Onnes, the pioneer of low temperature physics and superconductivity. Why should it not be possible that a combination of low temperature and solid state physics could lead to strange phenomena and, this is the most important point, to a large number of technical applications, but this time in the field of gravitational engineering? This is what this book is all about. Finally, in order for science to progress, both theorists and experimenters have to be willing to take a certain scientific risk that is, getting off the trodden path. If a blind alley is met, the courage to reverse one's direction of research is required. If, however, ideas of novel gravitational fields at cryogenic temperatures turn out to be true, the new scientific age of gravitational engineering might have begun:

A Debate Over the Physics of Time https://www.quantamagazine.org/20160719-time-and-cosmology/ " Many physicists argue that Einstein’s position is implied by the two pillars of modern physics: Einstein’s masterpiece, the general theory of relativity, and the Standard Model of particle physics. The laws that underlie these theories are time-symmetric — that is, the physics they describe is the same, regardless of whether the variable called “time” increases or decreases. Moreover, they say nothing at all about the point we call “now” — a special moment (or so it appears) for us, but seemingly undefined when we talk about the universe at large. The resulting timeless cosmos is sometimes called a “block universe” — a static block of space-time in which any flow of time, or passage through it, must presumably be a mental construct or other illusion. " If a ticking clock "measures" time, does that imply that time passes? If the flow of time were making the clock move, like above, then I would agree that clock really measures the velocity of time flow, or empirically detects its physical existence. However, the physical reason that clocks move (tick) is not that some physical time flows through them, so clocks neither detect nor measure anything other than themselves, I am afraid .... WHAT IS THE REASON THAT CLOCKS STOP ? CLOCKS ONLY STOP MEASURING TIME, WHEN TIME STOPS !!! What if time is only an illusion? What if it doesn't actually exist? Palle Yourgrau, a Brandeis professor of philosophy, explains that Einstein's general theory of relativity may allow for this possibility. It was first realized by the great logician Kurt Godel in a typically brief paper written for a Festschrift to honor his friend and Princeton neighbor Einstein. Godel is best known for his incompleteness theorem, one of the most important theorems in mathematical logic since Euclid. Palle Yourgrau writes that Godel's paper was almost universally ignored, and he claims that since the logician's death, philosophers have gone out of their way to try to denigrate his work in fields other than logic. In 1942, the logician Kurt Godel suffered a major episode of depression that required a stay at a mental hospital. Upon his release, Albert Einstein, his colleague at the Institute for Advanced Studies, took Godel under his wing and, to cheer him up, gave him "relativity lessons." The two became close friends; they walked to and from their offices at the Institute every day, exchanging ideas about science, philosophy, politics and the lost world of German science in which both men had grown up. By 1949, Godel had produced a remarkable proof: In any universe described by the Theory of Relativity, time cannot exist. Einstein endorsed this result – reluctantly, since it decisively overthrew the classical world-view to which he was committed. But he could find no way to refute it, and in the half-century since then, neither has anyone else. Even more remarkable than this stunning discovery by two of the greatest intellects of all time, however, was what happened afterward: nothing. Cosmologists have proceeded with their work as if time were the linear phenomenon familiar to Newton or Galileo (with some allowances for relativistic distortion); philosophers have refused to recognize Godel as an important philosopher of time. While arguing that these failures constitute major scandals of modern intellectual history, Palle Yourgrau also offers a mitigating explanation. Godel's cosmological findings, he says, are so advanced as to be beyond the ability of modern science to deal with them. A World without Time is a sweeping, ambitious book, and yet poignant and intimate – it tells the story of two magnificent minds put on the shelf by the scientific fashions of their day, and attempts to rescue from undeserved obscurity the brilliant work they did together.