Radio VLBI and the quantum interference paradox

Astronomy and Astrophysics Division, Physical Research Laboratory - Navrangpura, Ahmedabad - 380 009, India

^(a) ashokkumar.singal@gmail.com

Received: 12 January 2017
Accepted: 23 January 2017

Abstract

We address here the question of interference of radio signals from astronomical sources like distant quasars, in a very long baseline interferometer (VLBI), where two (or more) distantly located radio telescopes (apertures), receive a simultaneous signal from the sky. In an equivalent optical two-slit experiment, it is generally argued that for the photons involved in the interference pattern on the screen, it is not possible, even in principle, to know which of the two slits a particular photon went through and that any procedure to ascertain this destroys the interference pattern. But in the case of the modern radio VLBI, it is a routine matter to record the phase and amplitude of the voltage outputs from the two radio antennas on a recording media separately and then do the correlation between the two recorded signals later in an off-line manner. Does this not violate the quantum interference principle? We provide a resolution of this problem here.