Related papers: $c$ at the belfry
On the occasion of the laser's 50th anniversary, we performed a modern Fizeau experiment, measuring the speed of light with a laser beam passing over the city centre of Marseille. For a round trip distance of almost five kilometers, the…
The isotropy of the speed of light - the fundamental postulate of Special Relativity (SR) constrains conceptions of time, space and the existence of a preferred cosmological reference frame. Consequently, this phenomenon has been subject to…
This paper presents the outcome of an experiment based on an improved version of Fizeau's coupled-slotted-discs that tests the fundamental postulates of Special Relativity for the one-way speed of light propagation. According to our…
Abraham-Minkowski dilemma concerning the momentum of light within dielectric materials has persisted over 100 years[1]-[2] and conflicting experiments were reported until recently[3]-[4]. We perform a reversed Fizeau experiment to test the…
In the post-Maxwellian era, sensing that the tide of discoveries in electromagnetim indicated a decline of the mechanical view, Einstein replaced Newton's three absolutes -- space, time and mass, with a single one, the velocity of light.…
In this paper, we introduce two simple and inexpensive versions of the well-known Foucault method for measuring the speed of light. In a footprint of just 20 cm by 270 cm with readily available laboratory items and a webcam, we obtained…
In 1850, Foucault was the first to compare experimentally the velocity of light in air to its velocity in water. And as the wave and projectile theories competing at the time predicted inverse results to such a measurement, Foucault…
That the speed of light is always c=300,000km/s relative to any observer in nonaccelerating motion is one of the foundational concepts of physics. Experimentally this was supposed to have been first revealed by the 1887 Michelson-Morley…
At first blush, what appears to be a purely physical question to measure any velocity: how to measure the velocity on a one-way trip? However, due to the debates of the clock-synchronization and the successes of Special Relativity (SR),…
As we approach the 125th anniversary of the Michelson-Morley experiment in 2012, we review experiments that test the isotropy of the speed of light. Previous measurements are categorized into one-way (single-trip) and two-way (round-trip…
This problem was given at the Fourth Open and International Experimental Physics Olympiad (EPO4) Day of Light on 23 April 2016 in Sofia organized by the Sofia Branch of the Union of Physicists in Bulgaria and the Society of Physicists of…
Fizeau experiment, inspiring Einstein's special theory of relativity, reveals a small dragging effect of light inside a moving medium. Dispersion can enhance such light drag according to Lorentz's predication. Here we experimentally…
In Einstein's Special Theory of Relativity, all observers measure the speed of light, $c$, to be the same. However, this refers to the round trip speed, where a clock at the origin times the outward and return trip of light reflecting off a…
In this paper, we demonstrate a low-cost method to measure the speed of light. It uses instruments which are readily available in any undergraduate laboratory in a developing country and some components which are inexpensive. The method is…
In the 17th and 18th centuries, several natural philosophers studied the phenomenon of refraction and attempted to obtain the Snell law from various assumptions. Lacking experimental data, it was generally believed that light travels faster…
All experiments attempting to verify the invariance of speed of light directly are based on two-way speed measurement. The challenge in one-way speed measurement, the requirement of spatially separated synchronised clocks, can be possibly…
A powerful test of fundamental physics consists on probing the variability of fundamental constants in Nature. Although they have been measured on Earth laboratories and in our Solar neighbourhood with extremely high precision, it is…
The neutrino speed measurement experiments are the continuations of the classic light speed measurement experiments have been done in range of the solar planet system (Ole Roemer, 1676), in star system (James Braidely, 1728) and, at last,…
In this contribution the question of the isotropy of the one-way speed of light from an experimental perspective is addressed. In particular, we analyze two experimental methods commonly used in its determination. The analysis is aimed at…
Since 1983 the meter is defined to be the "length of the path travelled by light in vacuum during a time interval of 1/299792458 of a second". If there was exactly one single consistent method of synchronizing clocks, or if all…