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The gravitational fields of astrophysical bodies bend the light around them, creating multiple paths along which light from a distant source can arrive at Earth. Measuring the difference in photon arrival time along these different paths…
We report the first direct photon velocity measurements for extragalactic objects. A fiber-optic, photon time-of-flight instrument, optimized for relatively dim sources ($m 12$), is used to measure the velocity of visible photons emanating…
One of the cornerstones of special relativity is the postulate that all observers measure exactly the same photon speeds independently on the photon energies. However, a hypothesized structure of spacetime may alter this conclusion at…
In this paper we calculate the delay of the arrival times of visible photons on the focal plane of a telescope and its fluctuations as function of local atmospheric conditions (temperature, pressure, chemical composition, seeing values) and…
Using a \emph{gedanken} experiment providing presumably a minimal inaccuracy the uncertainty contributions to the space-time measurement are precisely evaluated for clock and mirror respectively. The resulting expression of minimal…
Signals from radio pulsars show a wavelength-dependent delay due to dispersion in the interstellar plasma. At a typical observing wavelength, this delay can vary by tens of microseconds on five-year time scales, far in excess of signals of…
Timing of highly stable millisecond pulsars provides the possibility of independently verifying terrestrial time scales on intervals longer than a year. An ensemble pulsar time scale is constructed based on pulsar timing data obtained on…
X-ray and gamma-ray observations of astrophysical objects at cosmological distances can be used to probe the energy dependence of the speed of light with high accuracy and to search for violations of Lorentz invariance and CPT symmetry at…
Quantum fluctuations can endow spacetime with a foamy structure. In this review article we discuss our various proposals to observationally constrain models of spacetime foam. One way is to examine if the light wave-front from a distant…
It is well-known that the light curve of a transiting planet contains information about the planet's orbital period and size relative to the host star. More recently, it has been demonstrated that a tight constraint on an individual…
Exploiting the correspondence between Wigner distribution function and a frequency-resolved optical gating (FROG) measurement, we experimentally demonstrate existence of the chessboard-like interference patterns with a time-bandwidth…
In this article, we propose an efficient time-splitting Fourier pseudospectral method for the Wigner(-Poisson)-Fokker-Planck equations. The method achieves second-order accuracy in time and spectral accuracy in phase space, both of which…
Transmission spectroscopy is currently the technique best suited to study a wide range of planetary atmospheres, leveraging the filtering of a star's light by a planet's atmosphere rather than its own emission. However, as both a planet and…
We show that space-based telescopes such as the proposed Terrestrial Planet Finder Coronagraph will be able to detect the light scattered by the interstellar grains along lines of sight passing near stars in our Galaxy. The relative flux of…
The distance to the stars is a fundamental parameter, which is determined via two primary methods - parallax and luminosity. While the parallax is a direct trigonometric method, the luminosity distance is usually influenced by interstellar…
During the Parker Solar Probe's (PSP) first perihelion pass, the spacecraft reached within a heliocentric distance of \(\sim 37~R_\odot\) and observed numerous magnetic and flow structures characterized by sharp gradients. To better…
Context: Extended circumstellar emission has been detected within a few 100 milli-arcsec around > 10% of nearby main sequence stars using near-infrared interferometry. Follow-up observations using other techniques, should they yield similar…
A model-independent statistical framework is presented to interpret data from systems where the mean time derivative of positional cross correlation between world lines, a measure of spreading in a quantum geometrical wave function, is…
I suggest that measurements of intensity fluctuations caused by classical wave interactions can be used to find unresolved gravitational lenses and determine time delays of essentially arbitrary length among the images formed by a…
The degree to which interstellar grains align with respect to the interstellar magnetic field depends on disaligning as well as aligning mechanisms. For decades, it was assumed that disalignment was due primarily to the random angular…