Günter Nimtz

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Günter Nimtz in the physics laboratory at Cologne University

Günter Nimtz (born September 22, 1936 in Berlin ) is a German physicist who is best known for his experiments in superluminal (faster than light) tunneling .

Life

Günter Nimtz initially obtained a diploma in electrical engineering in Mannheim , after studying physics at the Ruprecht-Karls-University in Heidelberg , he received his doctorate on hot charge carriers in Tellurium at the University of Vienna and habilitated in 1974 at the University of Cologne . In 2001 he retired and withdrew from the regular teaching and research activities of the Second Physics Institute. He taught and researched from 2002 to 2008 at the University of Koblenz-Landau . In 2004 he was visiting professor at the Universities of Shanghai and the Beijing University of Posts and Communications. His research areas were small band gap semiconductors, liquid crystals , bound water, photonics and the tunnel effect . He was also involved in various interdisciplinary studies on the interaction of non-ionizing electromagnetic radiation with biological systems. In addition, he carried out applied research with industry.

Research on the tunnel effect

In 1992, Nimtz doubted the measurement results of a tunnel experiment in Florence . The Italian physicists had determined a subluminal speed (lower speed of light) for the photons during tunneling . Together with his habilitation student Achim Enders, Nimtz measured the tunneling speed by means of microwaves in an undersized waveguide , in which propagation was classically forbidden. Their result was a faster than light propagation speed in the tunnel. Only when entering the constriction does a constant, very short period of time pass. Logically - and later also proven - the length of the tunnel has no influence on the tunnel time. The waves are largely reflected, or when viewed as particles, fewer particles get through the "tunnel".

In 1994, Nimtz, along with Horst Aichmann and Walter Strasser in the lab of Hewlett-Packard a spectacular experiment in which the microwaves with frequency modulation the 40th symphony by Mozart was impressed. These music signals were transmitted to microwaves through a barrier in the waveguide. They found, is that the music on the microwave modulated 4.7 times faster than spread light in a vacuum (see superluminal ).

Double prism experiment on the tunnel effect. The two prisms can be up to a meter apart until the microwaves can no longer be detected on the right prism.

Later, Nimtz and his colleague Alfons Stahlhofen from the University of Koblenz carried out precise measurements of the tunnel speed on a Plexiglas double prism (see picture on the right). It is irradiated with microwaves at an angle of incidence of 45 °. As expected, most of the radiation is reflected and emerges on the adjacent side of the prism. A very small part of the radiation emerges from the prism as "prevented (frustrated) total reflection", tunnels through the gap and re-enters the second prism.

The effect is also known as evanescent mode : An electromagnetic field cannot be reduced to zero immediately (instantaneously). If a second prism now enters this evanescent field, the field continues to spread normally. When viewed as particles, one can say that the particles have tunneled across the gap between the prisms. Günter Nimtz and Alfons Stahlhofen regard the results as the only proven violation of Albert Einstein's theory of special relativity (SRT) to date . The two physicists emphasize that the SRT does not apply in the tunnel, which represents a “space without time”. Because the measured tunnel time occurs at the barrier front, while in the barrier, i. H. No time is lost in the tunnel - space without time. The simple causality , i.e. the effect follows the cause, would not be violated according to Nimtz, because information can never be transferred into the past due to the temporal expansion of each signal. According to Nimtz and Stahlhofen, following the predictions of Richard P. Feynman , the tunnel effect can be explained with virtual photons, which are converted back into real photons at the end of the tunnel barrier.

criticism

After examining the tunnel experiment, physicists like Raymond Chiao (Berkeley) and Aephraim Steinberg (Toronto) paint a fundamentally different picture than Günter Nimtz. According to their analysis, the back part of a pulse is more attenuated than the front. Due to this deformation of the pulse, the detector receives a maximum earlier than if the pulse were attenuated evenly over its entire length. If you only consider the maximum of the pulse before and after the tunnel, the result is a speed that is higher than the propagation of the electromagnetic wave. In other words, the group speed is faster than the signal speed . You can also say that the detector only sees the first part of the pulse sent down the tunnel. In principle, information transmission faster than the speed of light is not possible in this way. A violation of causality through tunneling is excluded. The superluminal signal velocities during the tunneling process, interpreted in most textbooks and articles, have been corrected in reference to the point of view of Brillouin and other authoritative physicists.

Industrial research

An electromagnetic reflection-free hall with the new pyramid-shaped nano-metal film absorbers on the walls. In this case, a sports car is subjected to an electromagnetic compatibility test.

Günter Nimtz and Achim Enders patented a type of absorber for electromagnetic waves in 1993. It consists of a very thin aluminum film about 10 nm thick on pyramidal supports. The carrier can consist of an incombustible material. Compared to absorbers made of carbonated foam, the patented absorber type, which is now used worldwide, reduces the risk of fire in electromagnetic echo-free measurement halls. These are halls for determining the electromagnetic compatibility (EMC) of devices of all kinds, including cars and airplanes.

literature

Web links

Notes and individual receipts

  1. ^ G. Nimtz, A. Enders: On superluminal barrier traversal. In: Journal de Physique I. Volume 2, 1992, p. 1693.
  2. ↑ G. Nimtz: Instantaneous tunneling, tunnel experiments and electromagnetic waves In: Physikalische Blätter. Volume 49, 1993, p. 1119.
  3. ↑ G. Nimtz: Faster than light? In: Physics in Our Time. Volume 28, 1997, p. 214.
  4. ^ A b Günter Nimtz: Tunneling Confronts Special Relativity . In: Foundations of Physics . No. 41 , 2011, p. 1193 , doi : 10.1007 / s10701-011-9539-2 .
  5. ↑ In the special theory of relativity, a propagation of signals with faster than light speed would have the consequence, according to current interpretation, that signals could be transmitted into the past
  6. ↑ Chiao and others performed a similar experiment with a single photon: AM Steinberg, PG Kwiat, RY Chiao: Measurement of the Single-Photon Tunneling Time. In: Physical Review Letters. Volume 71, 1993, p. 708.
  7. ↑ H. Aichmann and G.Nimtz, Found. Phys. 44, 678 (2014)
personal data
SURNAME Nimtz, Günter
BRIEF DESCRIPTION German physicist
DATE OF BIRTH September 22, 1936
PLACE OF BIRTH Berlin