Günter Nimtz
Encyclopedia
Günter Nimtz is a German physicist, working at the 2nd Physics Institute at the University of Cologne
(Universität zu Köln) in Germany. He has investigated narrow-gap semiconductors and liquid crystals and was engaged in several interdisciplinary studies on the effect of non-ionizing electromagnetic radiation in biological systems. His international reputation mainly results from experiments that he claims show that particles may travel faster than the speed of light
(c) when undergoing quantum tunneling.
and became a professor of physics at the University of Cologne in 1983. He achieved emeritus status in 2001. During 2004 he was Visiting Professor at the University of Shanghai and of the Beijing University of Posts and Telecommunications
. From 2001 to 2008 he was teaching and doing fundamental research at the University of Koblenz-Landau.
s.
It is based on a 10 nano meter thick metal film placed on an incombustible pyramidal carrier. Compared with the classical carbon foam absorber, it is not toxic, incombustible and environmentally compatible. The absorber is distributed by the Frankonia company, patented and widely used on worldwide basis.
Professor Nimtz was consultant to the BAYER AG, to the Rheinmetall A.G., to the MERCK A.G./Darmstadt, and to the Feldmühle-Nobel A.G..
Between 2002 and 2007 he was a member of the Supervisory Board of ORMECON. Furthermore, he is Vicepresident of a Foundation for Disabled People.
after which Nimtz stated that the frequency modulated (FM) carrier wave transported the 40th symphony of Wolfgang Amadeus Mozart
4.7 times faster than light due to the effect of quantum tunneling.
A preprint published in 2007 by Profs. Günter Nimtz and Alfons Stahlhofen described an experiment which sent a beam of microwaves towards a pair of prisms. The angle provided for total internal reflection
and setting up an evanescent wave
. Because the second prism was close to the first prism, some light leaked across that gap. The transmitted and reflected waves arrived at detectors at the same time, despite the transmitted light having also traversed the distance of the gap. This is the basis for the assertion of faster-than-c transmission of information.
Actually, Nimtz and coworkers observed that the measured tunneling time is spent at the barrier front, whereas inside the barrier zero time is spent.
This result was observed in several tunneling barriers. Zero time tunneling was already calculated by Low and Mende in 1991.
or some other measure).
Furthermore, a recent paper by Herbert Winful was written in order to point out errors in Nimtz' interpretation. According to that article, far from contradicting special relativity, in reality Nimtz has rather provided a trivial experimental confirmation for it. Winful says that there is nothing specifically quantum-mechanical about Nimtz's experiment, that in fact the results agree with the predictions of classical electromagnetism
(Maxwell's equations
), and that in one of his papers on tunneling through undersized waveguides Nimtz himself had written "Therefore microwave tunneling, i.e. the propagation of guided evanescent modes, can be described to an extremely high degree of accuracy by a theory based on Maxwell's equations." (Elsewhere Nimtz has argued that since evanescent modes have an imaginary wave number, they represent a "mathematical analogy" to quantum tunnelling
, and that "evanescent modes are not fully describable by the Maxwell equations
and quantum mechanics have to be taken into consideration.") Since Maxwell's laws respect special relativity, Winful argues that an experiment which is describable using these laws cannot involve a relativistic causality violation (which would be implied by transmitting information faster than light). He also argues that "Nothing was observed to be traveling faster than light. The measured delay is the lifetime of stored energy leaking out of both sides of the barrier. The equality of transmission and reflection delays is what one expects for energy leaking out of both sides of a symmetric barrier."
Aephraim M. Steinberg of the University of Toronto
has also stated that Nimtz has not demonstrated causality violation (which would be implied by transmitting information faster than light). Steinberg also uses a classical argument. In a New Scientist article, he uses the analogy of a train traveling from Chicago to New York, but dropping off train cars at each station along the way, so that the center of the train moves forward at each stop; in this way, the speed of the center of the train exceeds the speed of any of the individual cars. Herbert Winful argues that the train analogy is a variant of the "reshaping argument" for superluminal tunneling velocities, but he goes on to say that this argument is not actually supported by experiment or simulations, which actually show that the transmitted pulse has the same length and shape as the incident pulse. Instead, Winful argues that the group delay in tunneling is not actually the transit time for the pulse (whose spatial length must be greater than the barrier length in order for its spectrum to be narrow enough to allow tunneling), but is instead the lifetime of the energy stored in a standing wave
which forms inside the barrier. Since the stored energy in the barrier is less than the energy stored in a barrier-free region of the same length due to destructive interference, the group delay for the energy to escape the barrier region is shorter than it would be in free space, which according to Winful is the explanation for apparently superluminal tunneling.
Apart from these interpretations further authors have published papers arguing that quantum tunneling does not violate the relativistic notion of causality, and that Nimtz's experiments (which are argued to be purely classical in nature) don't violate it either.
has been measured and that tunneling is the one and only observed violation of special relativity. However - in contradiction to their opponents - they explicitly point out that this does not lead to a violation of causality: Due to the temporal extent of any kind of signal it is impossible to transport information into the past. After all they claim that tunneling can generally be explained with virtual photons, the strange particles introduced by Richard Feynman
. In that sense it is common to calculate the imaginary tunneling wave number with the Helmholtz and the Schrödinger equations as Günter Nimtz did in and Herbert Winful did in . However, Nimtz highlights that eventually the final tunneling time was always obtained by the Wigner phase time approach. In and Günter Nimtz outlines that such evanescent modes only exist in the classically forbidden region of energy. As a consequence they cannot be explained by classical physics nor by special relativity postulates
: A negative energy of evanescent modes follows from the imaginary wave number, i.e. from the imaginary refractive index according to the Maxwell relation
for electromagnetic and elastic fields. In his latest publication Günter Nimtz again explicitly points out that tunneling indeed confronts special relativity and that any other statement must be considered incorrect.
University of Cologne
The University of Cologne is one of the oldest universities in Europe and, with over 44,000 students, one of the largest universities in Germany. The university is part of the Deutsche Forschungsgemeinschaft, an association of Germany's leading research universities...
(Universität zu Köln) in Germany. He has investigated narrow-gap semiconductors and liquid crystals and was engaged in several interdisciplinary studies on the effect of non-ionizing electromagnetic radiation in biological systems. His international reputation mainly results from experiments that he claims show that particles may travel faster than the speed of light
Faster-than-light
Faster-than-light communications and travel refer to the propagation of information or matter faster than the speed of light....
(c) when undergoing quantum tunneling.
Academic career
Günter Nimtz studied Electrical Engineering in Mannheim and Physics at the University of Heidelberg. He graduated from the University of ViennaUniversity of Vienna
The University of Vienna is a public university located in Vienna, Austria. It was founded by Duke Rudolph IV in 1365 and is the oldest university in the German-speaking world...
and became a professor of physics at the University of Cologne in 1983. He achieved emeritus status in 2001. During 2004 he was Visiting Professor at the University of Shanghai and of the Beijing University of Posts and Telecommunications
Beijing University of Posts and Telecommunications
The Beijing University of Posts and Telecommunications was founded as The Beijing Institute of Posts and Telecommunications in 1955. It was created under the Ministry of Posts and Telecommunications and the Communications Department of the General Staff Department of the People's Liberation Army...
. From 2001 to 2008 he was teaching and doing fundamental research at the University of Koblenz-Landau.
Industrial research and development
In 1993 Günter Nimtz and Achim Enders invented a novel absorber for electromagnetic anechoic chamberAnechoic chamber
An anechoic chamber is a room designed to stop reflections of either sound or electromagnetic waves.They are also insulated from exterior sources of noise...
s.
It is based on a 10 nano meter thick metal film placed on an incombustible pyramidal carrier. Compared with the classical carbon foam absorber, it is not toxic, incombustible and environmentally compatible. The absorber is distributed by the Frankonia company, patented and widely used on worldwide basis.
Professor Nimtz was consultant to the BAYER AG, to the Rheinmetall A.G., to the MERCK A.G./Darmstadt, and to the Feldmühle-Nobel A.G..
Between 2002 and 2007 he was a member of the Supervisory Board of ORMECON. Furthermore, he is Vicepresident of a Foundation for Disabled People.
Experiments related to superluminal quantum tunneling
Günter Nimtz and his coauthors have been investigating this subject since 1992. Since then numerous papers and articles have been published on well-known international conferences and in respected journals. Their preferred experimental setup involved microwaves either being sent across two space-separated prisms or through frequency-filtered waveguides. In the latter case either an additional undersized waveguide or a reflective grating structure had been used. In 1994 Günter Nimtz and Horst Aichmann carried out a tunneling experiment at the laboratories of Hewlett-PackardHewlett-Packard
Hewlett-Packard Company or HP is an American multinational information technology corporation headquartered in Palo Alto, California, USA that provides products, technologies, softwares, solutions and services to consumers, small- and medium-sized businesses and large enterprises, including...
after which Nimtz stated that the frequency modulated (FM) carrier wave transported the 40th symphony of Wolfgang Amadeus Mozart
Wolfgang Amadeus Mozart
Wolfgang Amadeus Mozart , baptismal name Johannes Chrysostomus Wolfgangus Theophilus Mozart , was a prolific and influential composer of the Classical era. He composed over 600 works, many acknowledged as pinnacles of symphonic, concertante, chamber, piano, operatic, and choral music...
4.7 times faster than light due to the effect of quantum tunneling.
A preprint published in 2007 by Profs. Günter Nimtz and Alfons Stahlhofen described an experiment which sent a beam of microwaves towards a pair of prisms. The angle provided for total internal reflection
Total internal reflection
Total internal reflection is an optical phenomenon that happens when a ray of light strikes a medium boundary at an angle larger than a particular critical angle with respect to the normal to the surface. If the refractive index is lower on the other side of the boundary and the incident angle is...
and setting up an evanescent wave
Evanescent wave
An evanescent wave is a nearfield standing wave with an intensity that exhibits exponential decay with distance from the boundary at which the wave was formed. Evanescent waves are a general property of wave-equations, and can in principle occur in any context to which a wave-equation applies...
. Because the second prism was close to the first prism, some light leaked across that gap. The transmitted and reflected waves arrived at detectors at the same time, despite the transmitted light having also traversed the distance of the gap. This is the basis for the assertion of faster-than-c transmission of information.
Actually, Nimtz and coworkers observed that the measured tunneling time is spent at the barrier front, whereas inside the barrier zero time is spent.
This result was observed in several tunneling barriers. Zero time tunneling was already calculated by Low and Mende in 1991.
Scientific opponents and their interpretations
Chris Lee has stated that there is no new physics involved here, and that the apparent faster-than-c transmission can be explained by carefully considering how the time of arrival is measured (whether the group velocityGroup velocity
The group velocity of a wave is the velocity with which the overall shape of the wave's amplitudes — known as the modulation or envelope of the wave — propagates through space....
or some other measure).
Furthermore, a recent paper by Herbert Winful was written in order to point out errors in Nimtz' interpretation. According to that article, far from contradicting special relativity, in reality Nimtz has rather provided a trivial experimental confirmation for it. Winful says that there is nothing specifically quantum-mechanical about Nimtz's experiment, that in fact the results agree with the predictions of classical electromagnetism
Classical electromagnetism
Classical electromagnetism is a branch of theoretical physics that studies consequences of the electromagnetic forces between electric charges and currents...
(Maxwell's equations
Maxwell's equations
Maxwell's equations are a set of partial differential equations that, together with the Lorentz force law, form the foundation of classical electrodynamics, classical optics, and electric circuits. These fields in turn underlie modern electrical and communications technologies.Maxwell's equations...
), and that in one of his papers on tunneling through undersized waveguides Nimtz himself had written "Therefore microwave tunneling, i.e. the propagation of guided evanescent modes, can be described to an extremely high degree of accuracy by a theory based on Maxwell's equations." (Elsewhere Nimtz has argued that since evanescent modes have an imaginary wave number, they represent a "mathematical analogy" to quantum tunnelling
Quantum tunnelling
Quantum tunnelling refers to the quantum mechanical phenomenon where a particle tunnels through a barrier that it classically could not surmount. This plays an essential role in several physical phenomena, such as the nuclear fusion that occurs in main sequence stars like the sun, and has important...
, and that "evanescent modes are not fully describable by the Maxwell equations
Maxwell's equations
Maxwell's equations are a set of partial differential equations that, together with the Lorentz force law, form the foundation of classical electrodynamics, classical optics, and electric circuits. These fields in turn underlie modern electrical and communications technologies.Maxwell's equations...
and quantum mechanics have to be taken into consideration.") Since Maxwell's laws respect special relativity, Winful argues that an experiment which is describable using these laws cannot involve a relativistic causality violation (which would be implied by transmitting information faster than light). He also argues that "Nothing was observed to be traveling faster than light. The measured delay is the lifetime of stored energy leaking out of both sides of the barrier. The equality of transmission and reflection delays is what one expects for energy leaking out of both sides of a symmetric barrier."
Aephraim M. Steinberg of the University of Toronto
University of Toronto
The University of Toronto is a public research university in Toronto, Ontario, Canada, situated on the grounds that surround Queen's Park. It was founded by royal charter in 1827 as King's College, the first institution of higher learning in Upper Canada...
has also stated that Nimtz has not demonstrated causality violation (which would be implied by transmitting information faster than light). Steinberg also uses a classical argument. In a New Scientist article, he uses the analogy of a train traveling from Chicago to New York, but dropping off train cars at each station along the way, so that the center of the train moves forward at each stop; in this way, the speed of the center of the train exceeds the speed of any of the individual cars. Herbert Winful argues that the train analogy is a variant of the "reshaping argument" for superluminal tunneling velocities, but he goes on to say that this argument is not actually supported by experiment or simulations, which actually show that the transmitted pulse has the same length and shape as the incident pulse. Instead, Winful argues that the group delay in tunneling is not actually the transit time for the pulse (whose spatial length must be greater than the barrier length in order for its spectrum to be narrow enough to allow tunneling), but is instead the lifetime of the energy stored in a standing wave
Standing wave
In physics, a standing wave – also known as a stationary wave – is a wave that remains in a constant position.This phenomenon can occur because the medium is moving in the opposite direction to the wave, or it can arise in a stationary medium as a result of interference between two waves traveling...
which forms inside the barrier. Since the stored energy in the barrier is less than the energy stored in a barrier-free region of the same length due to destructive interference, the group delay for the energy to escape the barrier region is shorter than it would be in free space, which according to Winful is the explanation for apparently superluminal tunneling.
Apart from these interpretations further authors have published papers arguing that quantum tunneling does not violate the relativistic notion of causality, and that Nimtz's experiments (which are argued to be purely classical in nature) don't violate it either.
Nimtz' interpretation
Nimtz and others argue that an analysis of signal shape and frequency spectrum has evidenced that a superluminal signal velocitySignal velocity
The signal velocity is the speed at which a wave carries information. It describes how quickly a message can be communicated between two separated parties...
has been measured and that tunneling is the one and only observed violation of special relativity. However - in contradiction to their opponents - they explicitly point out that this does not lead to a violation of causality: Due to the temporal extent of any kind of signal it is impossible to transport information into the past. After all they claim that tunneling can generally be explained with virtual photons, the strange particles introduced by Richard Feynman
Richard Feynman
Richard Phillips Feynman was an American physicist known for his work in the path integral formulation of quantum mechanics, the theory of quantum electrodynamics and the physics of the superfluidity of supercooled liquid helium, as well as in particle physics...
. In that sense it is common to calculate the imaginary tunneling wave number with the Helmholtz and the Schrödinger equations as Günter Nimtz did in and Herbert Winful did in . However, Nimtz highlights that eventually the final tunneling time was always obtained by the Wigner phase time approach. In and Günter Nimtz outlines that such evanescent modes only exist in the classically forbidden region of energy. As a consequence they cannot be explained by classical physics nor by special relativity postulates
Postulates of special relativity
- Postulates of special relativity :1. First postulate 2. Second postulate - Alternate Derivations of Special Relativity :...
: A negative energy of evanescent modes follows from the imaginary wave number, i.e. from the imaginary refractive index according to the Maxwell relation
for electromagnetic and elastic fields. In his latest publication Günter Nimtz again explicitly points out that tunneling indeed confronts special relativity and that any other statement must be considered incorrect.Related experiments
It was later claimed by the Keller group in Switzerland that particle tunneling does indeed occur in zero real time. Their tests involved tunneling electrons, where the group argued a relativistic prediction for tunneling time should be 500-600 attoseconds (an attosecond is one quintillionth of a second). All that could be measured was 24 attoseconds, which is the limit of the test accuracy. Again, though, other physicists believe that tunneling experiments in which particles appear to spend anomalously short times inside the barrier are in fact fully compatible with relativity, although there is disagreement about whether the explanation involves reshaping of the wave packet or other effects.Temporal conclusions and future research
Although his experimental results have been well documented since the early 1990s, Günter Nimtz' interpretation of the implications of these results represents a highly debated topic, which only a minority of researchers considers as correct.External links
- List of papers published by Prof. Nimtz at the site of University of CologneUniversity of CologneThe University of Cologne is one of the oldest universities in Europe and, with over 44,000 students, one of the largest universities in Germany. The university is part of the Deutsche Forschungsgemeinschaft, an association of Germany's leading research universities...
(including some full text.pdf files published before 2004). - G. Nimtz, A. Haibel, and R.-M. Vetter The Superluminal Features of Tunnelling. Proceedings of the International Conference 'Time's Arrows, Quantum Measurement and Superluminal Behavior, Naples, 2000', editors D. Mugnai, A Ranfagni, and L.S. Schulman (2001), ISBN 88-8080-024-8
- 'We have broken speed of light'
- A. Haibel, G. Nimtz, A. A. Stahlhofen Frustrated total reflection: The double-prisms revisited, Physical Review E, Vol. 63, 047601 (2001)
- G. Nimtz On superluminal tunneling, Progress in Quantum Electronics, Vol. 27, pp. 417–450 (2003)
- D. Müller, D. Tharanga, A.A. Stahlhofen, Nonspecular shifts of microwaves in parital reflection Europhysics Letters, Vol. 73, pp. 526–532 (2006)
- A.A. Stahlhofen, G. Nimtz, Evanescent modes are virtual photons, Europhysics Letters, Vol. 76, pp. 189–195 (2006)
- G. Nimtz Do Evanescent Modes violate Relativistic Causality Lecture Notes in Physics, Vol. 702, pp. 509–534, (2006)
- G. Nimtz, A.A. Stahlhofen, Evanescent Modes and Tunnelling Instantaneously Act at a Distance AIP Conference Proceedings Vol. 977, 310 (2007)