We know the speed of light is according to Einstein's postulate a constant. Is this a fundamental constant or is it just accurate to the best of our experimental knowledge? What physics lies beneath this accuracy?
Fundas : Speed = distance / time (Newtonian physics)
photons (packet of energy) being particles , time taken for them to travel is/was assumed to be constant because of our distance from sun or other planets !!!!
Or , c is inversely proportional to free space permittivity and premeability , that says the EM field of light and wave traveling in vacuum/ether ...
Alternatively , c= lambda * frq
again lambda is distance (in mts) and f= 1/t
Lambda won't get into details !!!!
I would rely on cosmic measurements !!!
I read some where 'c' is no longer a constant !!!
The answer to that depends on whether or not photons have mass. Everything about quantum mechanics is being questioned these days, including whether photons have (rest) mass. If photons are massless, they can only travel at v = c. Even the slightest amount of mass means that the speed of light would have SOME variability.
Those who support the massive photon arguments don't insist that the speed of light is perfectly constant. My question continues to be, do we have experimental evidence that the speed of light, through a vacuum, is even slightly variable? The massive photon theories go hand in hand with other similar theories about the variability of quantum states, which lead to the inevitable conclusion that quantum mechanics might just revert back to classical mechanics. Ain't that a kick in the pants?
What is constant is the product of the wavelength and the frequency of the electromagnetic wave in all inertial frames. This gives the maximum speed limit at which the quanta of electromagnetic energy can be transmitted from one location to another. This is a fundamental constant having an exact value c = 299792458 m/s with no uncertainty in measurement because the modern measurement technique involve simultaneous measurement of the length of the meter and the speed of light. Length of the meter is set at a fixed number of wavelengths.
This I think is a proof of the periodic nature of time. Newtons theory and Einstein's general relativity are based on linear time flowing from past to present to future, where as in reality you can only talk about a period of time between two events.
Article Periodic relativity: Basic framework of the theory
Dear Tony: The notion of mass is closely connected to that of particles as electrons or protons for example, the atoms are a set of these particles. The particles in the atoms includes the notion of motion (The hypothesis of a wave for the electron is misleading). To understand the motion between the particles, I suppose exchanges of very small grains mass which travel with the speed of the light. When a photon is emitted, we have flux of grains all traveling in the same direction. If we consider a plane perpendicular to the direction of the photon, the grains cross it in different point which are a projection of the orbit of the electron. As a result during the absorption they grains will communicate an angular or linear momentum corresponding to one unit of action h.
All our physics is built according to the relations between speed, mass and motion. With the hypothesis of small grains moving to the speed of the light, yes physics lies beneath this accuracy.
Dear Xavier and All
Happy New Year to you all.
I’m more interested in what the experiments say including any gerdanken than the theory but that’s important too. And this includes some of the original work of Planck and others over the past 120 years when classical theory was ruling the roost, and then probabilistic quantum theory was dominant for the last 100 years.
So my first question is as follows: If photons have mass, which is suggested by several if not many researchers, what is it that gives such an experimentally constant speed no matter what direction we look in? What does photon mass do to Planck’s Theory of the Blackbody and the later Quantum Field Theory?
We know from Planck’s blackbody work that this model is a very good approximation to what we observe. I won’t elaborate now on the cosmic rays that are present, nor the ‘dark matter’ for which we haven’t got an answer (or have we? See article on Dozy Chaos by Vladimir V. Ergodov http://aip.scitation.org/doi/pdf/10.1063/1.4889897). But these are big issues. Let’s concentrate just on photons flying around the Universe.
We know that a photon is now, after Planck’s work, called a ‘particle’ (or more correctly a ‘wave-particle’, and more recently two ‘wave-particles’). Imagine for a moment that photons can move in any direction within the ‘Blackbody’ (the Universe) with equal probability. (This is what Planck’s Law says) But this to a very accurate degree is what we see in COBE and WMAP. But if that’s so then are we living at the centre of the Universe since the speed of light is so constant no matter what direction we look in (Michelson and Morley 1887). The photons are moving along ‘giant circles’ in response to what happened at the moment of the Big Bang.
What we see in this early work is that the energy density of the Universe was considered isotropic and homogeneous. But that’s an approximation since the energy density depends on the dielectric and diamagnetic ‘constants’ for different volumes in space-time, for instance atoms, molecules, clouds including plasmas, planets, stars, galaxies, super galaxies, (universes) etc. What we find from the mathematics of Self-Field Theory is that photons will act as binding energy between atoms and between planets, etc (including in some interactions phonons which can be seen as longitudinal photons).
Blurring the wave-particle a bit (E= Plank's constant * f)
The modulation happens due to the medium in which light travels...
This is where the scattering or absorption theory or measurements accounts for !!
e.g Wavefronts upon diffusion thru materials (delayed) or otherwise traveling ones ...
What do you think about the idea to assume that the "grains" mentioned by @Xavier Oudet are
(1)
chaotically (quasi-stochastically) fluctuating objects (massless electric dipoles) which "fill the vacuum", i.e. they "embody space",
(2)
which can pass (to some part) to different types of non-chaotic "collective motion" in those regions of "space" where elementary particles or atoms or molecules or astronomic objects are present,
(3)
and to identify the collective motion with the allegged mechanism of exchange of some portions of "energy" and "momentum" and "angular momentum" in "interactions",
(4)
and to think of the fluctuating "grains" as the most fundamental physical processes which serve for a conceptual and operational definition of "events" and of "spatial distance" and "temporal distance" of some of the pairs of events, leading to the mathematical structure known as "special relativity" ?
If all of this this works without any contradictions, "special relativity" can be considered to be (onto)logically as "true" at least in the context of the used conceptual and operational definitions of "events" and "distance of events". Furthermore, this would indicate that the "grains" might be a part of physical reality or even embody the most fundamental building blocks of all "matter" and "radiation".
Understanding "grains" in this way corresponds to what is called "hypotrinos" in https://www.researchgate.net/project/Hypotron-Theory
HAPPY NEW YEAR 2018 !
Happy New Year,
Dear Karl: Thank for your recommendation. Concerning the hypotron your work is difficult for me I am from experimental formation and I just try to have a simple view of the corpuscular model. Now I share you citation:
Man cannot go to new shores, if he does not have the courage to leave the old ones.
Andre Gide (1869 - 1951, Nobel Prize in Literature 1947).
Dear All Now the question “Theoretically and experimentally why is the speed of light constant?” is closely connected to “The answer to that depends on whether or not photons have mass” as underling by Albert. About the mass of the photon my previous comment is a parallel which the particles or the notion of mass. All our physics is built according to the relations between speed, mass and motion, but what is the mass and what is a particle? It seems to me the difficulties are around these questions. Now for the mass of the photon I do not see how to consider it.
Dear Tony for the blackbody I have a work “The Black Body and the Dulong and Petit Law” using my work “Perturbations and Statistical Distribution of the Thermal Energy”, where the statistical approach use the notion of statistical, weight missing in Boltzmann approach.
Mass is proportional to energy (E=mc2 ) assuming c is a constant
Dear Dr Oudet, mass is associated with particulate character for example electron is a particle with a definite rest mass while a photon has no mass but is associated with energy.
Dear Bhendage, You are right but the question is “Theoretically and experimentally why is the speed of light constant?” So where are the experiments leading to this question? The difficulty is to take the time to separate the experiments from the mathematics. In this view an important point was the difficulty encounter with the light, supposed before Einstein, to move in a continuum ether.
We know that the electromagnetic field propagate to the speed of the light. This property allows to suppose that the electromagnetic interaction propagate with exchange of very small grains of mass between proton and electron, small grains having the speed of the light see “Quantum state and periodicity”. Thus the hypothesis of the photon is that it is a piece of energy make of small grains all moving in the same direction as already describe about three weeks ago: Dear Tony 30-12-17.
Now what is the mass? In fact the mass is a hypothesis giving important results to describe our observations as those leading to the classical mechanics. For example the “Principle of least action” also use in quantum mechanics. As a result the mass appears to be a structure between the grains. Karl G. Kreuzer19 days ago, has well underlined how the grains cans be seen responsible of different properties of the mechanics. The structure of the particles allows them to exchange grains leading to their relative motion. The grains of a photon all moving in the same direction does not have a structure thus the photon has no mass.
It's a nice question.
As we explore and learn more, we discover that our knowledge is limited in a specific territory to get it working.
Goes out of the territory, our custom known knowledge ought to get modified. Maybe the light speed is one of this kind knowledge. I do not know and can not give you a specific answer. Until you follow your intuition to go further to find out the solution.
The Speed of Light depends on the medium, slower in air, still slower in water, and more so in glass, etc... - or up to a spatial standstill, as in pair creation. So while gravity is still at odds with electric, weak and strong - photons are not to be trusted.
Dear Dr Oudet, Thank you for your explanation with regards absence of mass for photons. Mass appears as result of structure between the grains.Since the grains of photons all move in the same direction makes them incapable of exchange and no structure and hence massless. It appears quite interesting!
Dear All
Sir Isaac Newton studied the physics of cannonballs fired around the Earth from the tops of mountains; in other words these cannonballs follow a circular path at constant velocity around the Earth like modern satellites.
In self-field theory (a recent version of quantum physics) we see that photons (light) travel along circles between particles within and between atoms. It becomes an associated question as to whether light moves along circles at different levels of gravitation, if there is a fractal structure of gravitation observable within the Universe, for example at the solar system level, the gravitational level, the super cluster level and finally perhaps at the universal level. Perhaps light is acting as a small ‘satellite’.
Of course all this begs many other questions, but it does perhaps give a clue as to why we measure the speed of light as constant across physics regardless of direction as per Michelson-Morley experiment 1887.
Kind regards Tony
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