Superluminal signal velocity
نویسندگان
چکیده
منابع مشابه
Superluminal Signal Velocity
It recently has been demonstrated that signals conveyed by evanescent modes can travel faster than light. In this report some special features of signals are introduced and investigated, for instance the fundamental property that signals are frequency band limited. Evanescent modes are characterized by extraordinary properties: Their energy is negative, they are not directly measurable, and the...
متن کاملDirect measurement of superluminal group velocity and signal velocity in an optical fiber.
We present an easy way of observing superluminal group velocities using a birefringent optical fiber and other standard devices. In the theoretical analysis, we show that the optical properties of the setup can be described using the notion of "weak value." The experiment shows that the group velocity can indeed exceed c in the fiber; and we report the first direct observation of the so-called ...
متن کاملSuperluminal Velocity To Time Machines ?
Various experiments have shown superluminal group and signal velocities recently. Experiments were essentials carried out with microwave tunnelling [1], with frustrated total internal reflection [2], and with gain-assisted anomalous dispersion [3]. According to text books a superluminal signal velocity violates Einstein causality implying that cause and effect can be changed and time machines k...
متن کاملVariability and Velocity of Superluminal Sources
We investigate the relation between the Doppler factor determined from variations in total flux at 22 and 37 GHz, and the apparent transverse velocity determined from VLBA observations at 2 cm. The data are consistent with the relativistic beaming theory for compact radio sources, in that the distribution of β app /δ var , for 30 quasars, is roughly consistent with a Monte Carlo simulation. The...
متن کاملSuperluminal motion and closed signal curves
We discuss some properties of Lorentz invariant theories which allow for superluminal motion. We show that, if signals are always sent forward in time, closed curves along which signals propagate can be formed. This leads to problems with causality and with the second law of thermodynamics. Only if one singles out one frame with respect to which all signals travel forward in time, the formation...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Annalen der Physik
سال: 1998
ISSN: 0003-3804,1521-3889
DOI: 10.1002/(sici)1521-3889(199812)7:7/8<618::aid-andp618>3.0.co;2-p