Ask Ethan: Does Light Always Move At The Same Speed? (Synopsis)

“There was a young lady named Bright,
Whose speed was far faster than light;
She set out one day
In a relative way,
And returned on the previous night.” -A.H. Reginald Butler

Throughout the entire Universe, there’s a fundamental law that governs the motions of all particles: Einstein’s relativity. It states that all particles with mass can never attain the speed of light, no matter how much energy you put into it. Additionally, all massless particles only move at the speed of light, no matter what you do to either them or to the device/person observing them. No matter what reference frame you’re in, the speed of light in a vacuum is a constant.

The size, wavelength and temperature/energy scales that correspond to various parts of the electromagnetic spectrum. Image credit: NASA and Wikimedia Commons user Inductiveload.

But light isn’t always in a vacuum!  From air to quartz to acrylic to glass to many other media, light can pass through transparent material, and when it does, it slows down. Not only that, but light of different energy slows down by different amounts. In what ways is the speed of light always the same, and in what ways can it change?

The behavior of white light as it passes through a prism demonstrates how light of different energies move at different speeds through a medium, but not through a vacuum. Image credit: University of Iowa.

And most importantly, what do the known properties of light mean for the rest of the Universe? Find out on this edition of Ask Ethan!

8 thoughts on “Ask Ethan: Does Light Always Move At The Same Speed? (Synopsis)

  1. Experiments have unequivocally proved that both subluminal motion of light in a vacuum and superluminal motion are possible but the scientific community cannot react properly because Einsteinians bombard it with contradictory and confusing explanations, often involving “group velocity” and “phase velocity”. The experimentalists themselves have to include such explanations in their articles – otherwise there would be no publication. Yet even “group velocity” and “phase velocity” turn out to be insufficiently confusing and Einsteinians resort to the ultimate weapon – the speed of some mysterious entity called “information” – as if Einstein had based his 1905 second postulate on the speed of information, not on the speed of light. This speed always gloriously conforms to Divine Albert’s Divine Theory:

    Robert W. Boyd, Daniel J. Gauthier, Controlling the Velocity of Light Pulses: “So why do laboratory results of fast light not necessitate the superluminal transfer of information? It is believed that the explanation lies in the distinction between Vg [group velocity] and the information velocity. The group velocity can take on any value. However, the information velocity can never exceed c and, according to many models, is always equal to c.”

    If it were not for the schizophrenic and confusing atmosphere created by Einsteinians, the inconstancy of the speed of light would be an obvious experimental fact:

    Science 20 Feb 2015: Vol. 347, Issue 6224, pp. 857-860: “Spatially structured photons that travel in free space slower than the speed of light”

    Quote: “Physicists manage to slow down light inside vacuum […] …even now the light is no longer in the mask, it’s just the propagating in free space – the speed is still slow. […] “This finding shows unambiguously that the propagation of light can be slowed below the commonly accepted figure of 299,792,458 metres per second, even when travelling in air or vacuum,” co-author Romero explains in the University of Glasgow press release.”

    Quote: “The speed of light is a limit, not a constant – that’s what researchers in Glasgow, Scotland, say. A group of them just proved that light can be slowed down, permanently.”

    Quote: “Although the maximum speed of light is a cosmological constant – made famous by Einstein’s Special Theory of Relativity and E=mc^2 – it can, in fact, be slowed down: that’s what optics do.”

    Video on YouTube: “Dunya News | Glasgow researchers slow the speed of light”

    Quote: “For generations, physicists believed there is nothing faster than light moving through a vacuum — a speed of 186,000 miles per second. But in an experiment in Princeton, N.J., physicists sent a pulse of laser light through cesium vapor so quickly that it left the chamber before it had even finished entering. The pulse traveled 310 times the distance it would have covered if the chamber had contained a vacuum. Researchers say it is the most convincing demonstration yet that the speed of light — supposedly an ironclad rule of nature — can be pushed beyond known boundaries, at least under certain laboratory circumstances. […] The results of the work by Wang, Alexander Kuzmich and Arthur Dogariu were published in Thursday’s issue of the journal Nature.”

    Nature 406, 277-279 (20 July 2000): “…a light pulse propagating through the atomic vapour cell appears at the exit side so much earlier than if it had propagated the same distance in a vacuum that the peak of the pulse appears to leave the cell before entering it.”

    Quote: “Researchers at the University of Ottawa observed that twisted light in a vacuum travels slower than the universal physical constant established as the speed of light by Einstein’s theory of relativity. […] In The Optical Society’s journal for high impact research, Optica, the researchers report that twisted light pulses in a vacuum travel up to 0.1 percent slower than the speed of light, which is 299,792,458 meters per second. […] If it’s possible to slow the speed of light by altering its structure, it may also be possible to speed up light. The researchers are now planning to use FROG to measure other types of structured light that their calculations have predicted may travel around 1 femtosecond faster than the speed of light in a vacuum.”

    Quote: “Speed of light broken with basic lab kit. Electric signals can be transmitted at least four times faster than the speed of light using only basic equipment that would be found in virtually any college science department. Scientists have sent light signals at faster-than-light speeds over the distances of a few metres for the last two decades – but only with the aid of complicated, expensive equipment. Now physicists at Middle Tennessee State University have broken that speed limit over distances of nearly 120 metres, using off-the-shelf equipment costing just $500. […] While the peak moves faster than light speed, the total energy of the pulse does not. This means Einstein’s relativity is preserved, so do not expect super-fast starships or time machines anytime soon.”

    Quote: “Light that travels… faster than light! […] This is exactly what the EPFL team has demonstrated. Using their Stimulated Brillouin Scattering (SBS) method, the group was able to slow a light signal down by a factor of 3.6, creating a sort of temporary “optical memory.” They were also able to create extreme conditions in which the light signal travelled faster than 300 million meters a second. And even though this seems to violate all sorts of cherished physical assumptions, Einstein needn’t move over – relativity isn’t called into question, because only a portion of the signal is affected.”

    Quote: “Light Pulses That Travel Faster Than Light Created […] The technique developed at NIST is called four-wave mixing, and it works by altering some parts of each individual light pulse. This makes the light move forward faster than it normally would when traveling through a vacuum. […] The physicists explain that the new research does not violate Albert Einstein’s theory on general relativity – which states that the speed of light in a vacuum is the fastest achievable in the Universe. They say that a sort of loophole exists in this theory. By careful tuning of the light source and advanced calculations, it is possible to nudge portions of the light pulses so that they arrive at their destination ahead or behind the main pulse. […] With four-wave mixing, the NIST investigators produced laser pulses that arrived at their destination a full 50 nanoseconds faster than photons traveling through a vacuum.”

    Quote: “Light hits near infinite speed in silver-coated glass. A nano-sized bar of glass encased in silver allows visible light to pass through at near infinite speed. The technique may spur advances in optical computing. […] In a vacuum the refractive index is 1, and the speed of light cannot break Einstein’s universal limit of 300,000 kilometres per second. Normal materials have positive indexes, and they transmit at the speed of light in a vacuum divided by their refractive index. Ordinary glass, for instance, has an index of about 1.5, so light moves through it at about 200,000 kilometres per second. The new material contains a nano-scale structure that guides light waves through the metal-coated glass. It is the first with a refractive index below 0.1, which means that light passes through it at almost infinite speed, says Albert Polman at the FOM Institute AMOLF in Amsterdam, the Netherlands. But the speed of light has not, technically, been broken. The wave is moving quickly, but its “group velocity” the speed at which information is travelling is near zero.”

  2. Einstein plagiarized (“borrowed”) the false constancy of the speed of light from the Lorentz equations, called it “postulate”, and finally derived, for the gullible world, the Lorentz equations from the “postulate” (reverse engineering):

    Albert Einstein: “…I introduced the principle of the constancy of the velocity of light, which I borrowed from H. A. Lorentz’s theory of the stationary luminiferous ether…”

    John Stachel explains that the constancy of the speed of light seemed nonsense to Einstein but he introduced it nevertheless:

    John Stachel: “But this seems to be nonsense. How can it happen that the speed of light relative to an observer cannot be increased or decreased if that observer moves towards or away from a light beam? Einstein states that he wrestled with this problem over a lengthy period of time, to the point of despair.”

    Indeed, the idea that the speed of light is independent of the speed of the observer is nonsense disproved by many experiments, e.g. measurements of the Doppler frequency shift:

    Quote: “Let’s say you, the observer, now move toward the source with velocity vo. You encounter more waves per unit time than you did before. Relative to you, the waves travel at a higher speed: v’=v+vo. The frequency of the waves you detect is higher, and is given by: f’=v’/λ=(v+vo)/λ.”

    Quote: “vo is the velocity of an observer moving towards the source. This velocity is independent of the motion of the source. Hence, the velocity of waves relative to the observer is c + vo. […] The motion of an observer does not alter the wavelength. The increase in frequency is a result of the observer encountering more wavelengths in a given time.”

    The introduction of the false postulate was Einstein’s original sin. The malignancy was there but it was sterile – all VALIDLY deducible consequences of the false postulate were obviously absurd and repugnant. However Einstein’s second sin – a fraudulent and INVALID deduction – produced a miraculous result that was irresistibly attractive. In 1905 Einstein derived, from his two postulates, the conclusion “the clock moved from A to B lags behind the other which has remained at B”:

    Albert Einstein, On the Electrodynamics of Moving Bodies, 1905: “From this there ensues the following peculiar consequence. If at the points A and B of K there are stationary clocks which, viewed in the stationary system, are synchronous; and if the clock at A is moved with the velocity v along the line AB to B, then on its arrival at B the two clocks no longer synchronize, but the clock moved from A to B lags behind the other which has remained at B by tv^2/2c^2 (up to magnitudes of fourth and higher order), t being the time occupied in the journey from A to B.”

    The conclusion

    “The clock moved from A to B lags behind the other which has remained at B”

    does not follow from Einstein’s 1905 postulates – the argument is INVALID. The following two conclusions, in contrast, VALIDLY follow from the postulates:

    Conclusion 1: The clock moved from A to B lags behind the other which has remained at B, as judged from the stationary system.

    Conclusion 2: The clock which has remained at B lags behind the clock moved from A to B, as judged from the moving system.

    Conclusions 1 and 2 (symmetrical time dilation) in their combination give no prediction for the readings of the two clocks as they meet at B – in this sense the false postulate is sterile. In contrast, the INVALIDLY deduced conclusion provides a straightforward prediction – the moving clock is slow, the stationary one is FAST (asymmetrical time dilation). The famous “travel into the future” is a direct implication – the slowness of the moving clock means that its (moving) owner can remain virtually unchanged while sixty million years are passing for the stationary system:

    Thibault Damour: “The paradigm of the special relativistic upheaval of the usual concept of time is the twin paradox. Let us emphasize that this striking example of time dilation proves that time travel (towards the future) is possible. As a gedanken experiment (if we neglect practicalities such as the technology needed for reaching velocities comparable to the velocity of light, the cost of the fuel and the capacity of the traveller to sustain high accelerations), it shows that a sentient being can jump, “within a minute” (of his experienced time) arbitrarily far in the future, say sixty million years ahead, and see, and be part of, what (will) happen then on Earth. This is a clear way of realizing that the future “already exists” (as we can experience it “in a minute”).”

    The year 1905 can be regarded as the year of the death of physics. Science died and idiotic ideology was born.

    Peter Woit: “I think the worst thing that has happened to theoretical physics over the past 25 years is this descent into ideology, something that has accelerated with the multiverse mania of the last 10-15 years.”

    Correct, except for the number 25 – it should be replaced by 112:

    Peter Hayes, The Ideology of Relativity: The Case of the Clock Paradox: “This paper investigates an alternative possibility: that the critics were right and that the success of Einstein’s theory in overcoming them was due to its strengths as an ideology rather than as a science. The clock paradox illustrates how relativity theory does indeed contain inconsistencies that make it scientifically problematic. These same inconsistencies, however, make the theory ideologically powerful. […] The gatekeepers of professional physics in the universities and research institutes are disinclined to support or employ anyone who raises problems over the elementary inconsistencies of relativity. A winnowing out process has made it very difficult for critics of Einstein to achieve or maintain professional status. Relativists are then able to use the argument of authority to discredit these critics. Were relativists to admit that Einstein may have made a series of elementary logical errors, they would be faced with the embarrassing question of why this had not been noticed earlier. Under these circumstances the marginalisation of antirelativists, unjustified on scientific grounds, is eminently justifiable on grounds of realpolitik. Supporters of relativity theory have protected both the theory and their own reputations by shutting their opponents out of professional discourse. […] The triumph of relativity theory represents the triumph of ideology not only in the profession of physics bur also in the philosophy of science.”

  3. The constancy of the speed of light was originally refuted in 1887. Einsteinians teach that in 1887 the Michelson-Morley experiment disproved the existence of the ether but did not disprove the independence of the speed of light from the speed of the source, a tenet of the ether theory later adopted by Einstein as his 1905 second postulate. This is a blatant lie – the truth is that in 1887 the Michelson-Morley experiment UNEQUIVOCALLY disproved the source-independent speed of light and confirmed the source-dependent speed of light predicted by Newton’s emission theory of light.

    The prediction of Michelson and Morley was not calculated from the premise “There is an ether”. It was calculated from the crucial premise

    “The speed of light is independent of the speed of the light source”

    and since the experimental result did not match the prediction, one should have concluded, logic dictated it, that the crucial premise is false. Michelson and Morley and other physicists did not come to this conclusion of course because they were all etherists.

    In their teaching courses Einsteinians do not state the crucial premise as explicitly as I did above, but they cannot completely hide it either. Here is an example:

    Richard Feynman: “First, let us calculate the time required for the light to go from B to E and back. Let us say that the time for light to go from plate B to mirror E is t_1, and the time for the return is t_2. Now, while the light is on its way from B to the mirror, the apparatus moves a distance ut_1, so the light must traverse a distance L + ut_1, at the speed c.”

    Feynman’s last phrase,

    “at the speed c”,

    is equivalent to the crucial premise stated above. If, instead of “at the speed c”, we have a new premise,

    “at the speed c + u”,

    taken from Newton’s emission theory of light, the calculation (based on the new premise) will give a new prediction,

    t_1 + t_2 = 2t_3 = 2L/c,

    which exactly matches the null result of the Michelson-Morley experiment.

  4. “… Einsteinians bombard it [scientific community] …”

    Pentcho Valev,

    Since you introduced the issue of bombardment, I feel comfortable pointing out that your first three posts to this thread contained

    > 2,650 words
    > 13,460 characters (without spaces)
    > 40 paragraphs

    Respectfully, is there any chance you’ll be kind enough to lighten up on this community a bit?

    Thanks in advance,

    John

  5. I thing that Those photons of stars Which vertically impact The event horizon (their travelling rout is 90 degrees wih respect to The event horizon ) get a speed of faster than The speed of light in vacum when They reach nearer The event horizon

  6. Pentcho Valev, you are not contributing anything to the comments except walls of text.
    Please stop.
    Ethan, please ask Pentcho Valev to stop too.

  7. Just sayin’ to Pentcho, THANKS for the “wall of text”. I appreciate the overview in one convenient place. I’ve suspected the seeming “constant” speed of light has more to do with the assumption of time as a constant, and I’m grateful for this easy path to see what folks are up to in the area.

  8. I’ve suspected the seeming “constant” speed of light has more to do with the assumption of time as a constant

    Even the most rudimentary study would tell you that Special Relativity overthrew the assumption of time as a constant.

    and I’m grateful for this easy path

    Indeed. Why put a bunch of effort into understanding a century’s worth of physics when Pentcho so readily supports your arrogant assumptions. Study is hard; confirmation bias is easy.

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