Lights illuminate surfaces superluminally

Nemiroff, R. J.; Zhong, Qi; Lilleskov, Elias

doi:10.1088/0031-9120/51/4/043005

Cited by 8 publications

(6 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Given the tremendous variety of curved filaments possible, quantifying illumination changes generally appears quite complex and is considered beyond the scope of the present work. More complex filament geometries, including curved geometries, will be examined in greater detail in a later work (Nemiroff 2017). A detailed example of how a flash illuminates a flat surface has been recently completed by Zhong (2016).…”

Section: Discussionmentioning

confidence: 99%

Light Echoes from Linear Filaments

Nemiroff,

Zhong

2017

Preprint

Self Cite

View full text Add to dashboard Cite

When a flash of light from a star overtakes a straight linear filament of gas or dust and is seen later by an observer, a pattern of perceived illumination occurs that encodes information about the distance to the flash, the distance to illumination fronts on the filament, and the orientation of the filament. To help decode this information, geometric considerations of light echoes from such filaments are considered. A distinction is made between real spots, which occur unambiguously on a filament, and perceived spot echoes, which are seen by observers and may appear differently to separated observers. For context, a series of critical points are defined on a hypothetically infinite filament. Real spot pair creation events will only occur on an infinite filament at the closest distance to the flash, while perceived spot pair events will only occur when the radial speed component toward the observer of a real spot crosses the speed of light. If seen, a perceived spot pair creation event could provide unique information toward decoding distance and orientation information of the flash and the filament. On filament segments, typically only one of these perceived spots will be seen. Geometries where a perceived spot appears to move with an angular component toward the flash are shown possible. Echo and source distance determinations for filaments that pass between the observer and flash are considered. Hypothetical examples are given for Merope variably illuminating IC 349, and Rigel creating perceived spots on IC 2118.This paper is structured as follows. Section 2 will review background concepts and define terms that make it convenient to understand and describe how light echoes may occur and appear from flashes on straight linear filaments. Section 3 will explore the general properties of spot motions,

show abstract

Section: Discussionmentioning

confidence: 99%

Light Echoes from Linear Filaments

Nemiroff,

Zhong

2017

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…Similarly, the value of x where the vertex speed v exceeds c will be called x c and can be found by integrating equation (2). The result is…”

Section: Rotating Upper Bladementioning

confidence: 99%

“…A common expression is that nothing can travel faster than light -but this is not strictly true. Shadows, for example, are a well known counter example 1,2 . Conversely, it is common lore [3][4][5][6] in physics that the vertex of a pair of scissors can exceed c but no comprehensive pedagogical account of this exists.…”

Section: Introductionmentioning

confidence: 99%

Analyses of scissors cutting paper at superluminal speeds

Kaushal

Nemiroff

2019

Phys. Educ.

Self Cite

View full text Add to dashboard Cite

A popular physics legend holds that scissors can cut paper with a speed faster than light. Here this counter-intuitive myth is investigated theoretically using four simple examples of scissors. For simplicity, all cases will involve a static lower scissors blade that remains horizontal just under the paper. In the first case, the upper blade will be considered perfectly rigid as it rotates around and through the paper, while in the second case, a rigid upper blade will drop down to cut the paper like a guillotine. In the third case, the paper is cut with a laser rotating with a constant angular speed that is pointed initially perpendicular to the paper at the closest point, while in the fourth case, the uniformly rotating laser is pointed initially parallel to the paper. Although details can be surprising and occasionally complex, all cases allow sections of the paper to be cut faster than light without violating special relativity. Therefore, the popular legend is confirmed, in theory, to be true.

show abstract

“…However, it is well known that wave and illumination fronts may exceed the speed of light if they are not tied to mass or to transmitting locally produced information: consider, for instance, an illuminated spot from a lighthouse moving along a distant mountain wall, the propagation of shadows, or the illumination front of any intrinsically variable source of light (see, for instance, [3,4]). In all these cases, neither mass nor energy (or information) originates at one end of the traveled distance and moves to the other end.…”

Section: Introductionmentioning

confidence: 99%

On apparent faster-than-light behavior of moving electric fields

D’Abramo

2021

Eur. Phys. J. Plus

View full text Add to dashboard Cite

For every observer, however distant, the electric field of a uniformly moving charge is always directed away from, or points towards, the instantaneous present position of the charge and not away from, or towards, the retarded position at which the observer sees it (due to the finite speed of light). This fact is a well-established consequence of, among others, the application of the Liénard-Wiechert potentials, and its significance for fundamental physics is probably not fully appreciated. Here we show how and why this property has non-negligible consequences for what we take for granted about the relativity of simultaneity and faster-than-light communication. In particular, if we consider two opposite electric charges whose distance shrinks to zero at a constant velocity (shrinking electric dipole), then the cancellation of the total field seems to be instantaneous everywhere in space and in every inertial reference frame. A simple variant of the shrinking electric dipole setup appears to allow a sort of faster-than-light communication of information. Our results provide simple theoretical support to the conclusions of recent experiments on the propagation speed of Coulomb and magnetic fields. It would also be interesting to explore any possible connection between our findings and quantum 1

show abstract

Lights illuminate surfaces superluminally

Cited by 8 publications

References 3 publications

Light Echoes from Linear Filaments

Light Echoes from Linear Filaments

Analyses of scissors cutting paper at superluminal speeds

On apparent faster-than-light behavior of moving electric fields

Contact Info

Product

Resources

About