Researchers test speed of light with greater precision than before

Researchers test speed of light with greater precision than before

Researchers from The University of Western Australia and Humboldt University of Berlin have completed testing that has effectively measured the spatial consistency of the speed of light with a precision ten times greater than ever before.

The stringent testing also confirmed a core component of Einstein's theory of Relativity known as 'Lorentz ,' which predicts that the is the same in all directions.

The experiment compared the extremely pure microwave frequency signals from two cryogenic sapphire oscillators against each other over the course of a year.

UWA Researcher Stephen Parker from the Frequency and Quantum Metrology Research Group at the School of Physics said the experiment placed the microwave oscillators perpendicular to each other and rotated them on a turntable once every 100 seconds for a year.

"The frequency of the microwave signals directly linked to the speed of light," Dr Parker said.

"If this were to change depending on the direction it was facing it would indicate that Lorentz symmetry had been violated. But the frequencies didn't even change down to the 18th digit (the smallest part of the measurement of frequency), which is remarkable that this symmetry of nature still holds true at such tiny levels."

Dr Parker said the research team were in the process of upgrading their experiment and incorporating new optical sources which would open up possibilities for future research.

"This will allow us to improve the sensitivity of our work and explore other ways that Lorentz symmetry could be broken," he said.

"Searching for possible violations of Lorentz symmetry will provide valuable clues for a more comprehensive and unified theory."

The research has been published in Nature Communications.


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More information: "Direct terrestrial test of Lorentz symmetry in electrodynamics to 10−18" Nature Communications 6, Article number: 8174 DOI: 10.1038/ncomms9174
Journal information: Nature Communications

Citation: Researchers test speed of light with greater precision than before (2015, September 14) retrieved 16 July 2019 from https://phys.org/news/2015-09-greater-precision.html
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Sep 14, 2015
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Sep 14, 2015
Interesting study, considering that the speed of light is defined to its exact value. These studies will probably change the length of the meter instead. Or a few meters in c.

Sep 14, 2015
These studies will probably change the length of the meter instead.

It will reduce the error bars but they didn't measure a new speed of light ('just' validated consistency).

Sir,
The Speed of Light is being measured utilizing a laser beam. There is much dissimilarity between a Laser light and the light of celestial sources e.g., Laser beam originates from a two-dimensional flat surface of a narrow cylindrical tube, but light of celestial sources like the Sun – emanates from a three-dimensional spherical surface. Laser light travels in the form of a beam – retaining the same intensity; whereas, light emanated from the spherical Sun expands – concurrently decreasing the intensity. Therefore, we cannot decide the speed of light by measuring it in a beam form. In reality, Light of celestial sources makes contact with an object at an unimaginable speed (pl. ref. article: "Reconciliation of the discrepancies in the speed of Light" published in IJIRD Journal). This discovery will reconcile the existing controversy about the speed of light. Thank you.

Sep 14, 2015
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Sep 14, 2015
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Sep 14, 2015
it still amazes me

Sep 14, 2015
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Sep 14, 2015
You do know it's simpler to know the emitted wavelength then simply measure how fast it moves past, i.e. 1/nu_observed; therefore, speed will be:

C * lambda_emitted/lambda_observed.

GR, or changing the shape of space and time implies space is magic, a recipe for nonsensical physics! Try an emission from an accelerated frame with a constant wavelength. Nothing necessary as a complicated tensor that does not even make common sense, GR implies that momentum is a function of displacement and ignores or doesn't understand the relative speed of the wave-front. Simple math and physics and wisdom, not assumptions. Update our definition of the Poynting Vector.

Sep 14, 2015
Measuring within a stationary frame does nothing to define the relative speed of light relative to all moving bodies. Try a really fast mechanical oscillator moving along a single line. Not sure this will even be effective since it would require a great speed. Ask NASA what frequency they measure from an accelerating probe based upon the initial wavelength. Or notice the discrepancy when we make assumptions when communicating with satellites. Don't give credit to Dr. E, blame the engineers for not considering the relative velocity of each object in order to account for error. No need for GR! Better yet, ask CERN how an optical coupler may be open by more than a meter or define the media with the properties that defined the messed up multiple measure. Simple, and not be noted during initial checks? Incompetence! Assumptions are not truths. No I cannot accept this theory. Can't get my head around it. Far too many bad things about this whole idea. Doesn't make sense!

Sep 14, 2015
Also, different sources, lasers, proton collisions, light bulbs, LEDs, frames in motion of the emitter relative to us, accelerated, constant velocity, circular motion, ellipsoidal, blah, blah, blah. All different sources. We are not even close to a well defined experiment! Unfounded conclusions. So what are we measuring, something I call a propagation constant, lambda nu, or the speed of a constant wavelet, i.e. how fast the object moves through space? Speed of wave-front. Hypothetically, think of a wavelet as a containment, totally enclosed wave, how fast does the container move past us? For me this is logic, not a puzzle. It's length divided by the time it takes to pass! Wavelength is fixed unless passing through some media, empty space does not alter the wavelength, unless we have an error within our universal constants such as permittivity & permeability of empty space as a function of distance. Either way, this experiment is inadequate.

Sep 14, 2015
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Sep 14, 2015
I can't comment on the technical (equipment) issues but the article kind of 'bugs' me, something I just can't put my finger on as it were. It seems that at the beginning they are just using a more advanced setup to M&M exp. the results of which they seem to have confirmed. So that's about the limit of what can be claimed. It will be more interesting when a setup is organised for space travel which, imo, is another object of this research. But then the end of the article,"Searching for possible violations of Lorentz symmetry will provide valuable clues for a more comprehensive and unified theory."
being more concerned with violations perhaps trying to cover up some ulterior motive and which might cloud any interpretation they might make. Ha! just my suspicious nature I guess.

Sep 15, 2015
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Sep 15, 2015
It's sorta waste of tax payer's money.
@ZEPHIR/docile
no... wasting taxpayer money would be something like: investigating something like aether when it has been proven to be pseudoscience & directly falsified with empirical evidence
it was falsified, then validated (like here: http://exphy.uni-...2009.pdf )
But now it is actually validated to a higher degree/precision... making your daw/aw even more pseudoscience than before...!

Sep 20, 2015
Testing the speed of light with equipment that uses electricity...goes the speed of light. Like in computers, garbage in...garbage out.

Light from the Sun does not take eight minutes to reach Earth. The Light emanated from the spherical surface of the Sun with an Intensity of approximately 63,000,000 Wm-2, expands 46,157 Times - concurrently decreasing the Intensity, and makes contact with the Planet in the form of an Expanded Sphere; so that, Planet Earth gets the Sunlight with an average Intensity of 1,365 Wm-2 - at the top of its atmosphere. The Intensity of Sunlight obtained by Earth as per the Theoretical Calculations - precisely agrees with the practical data collected by way of space probes. It is evident that the Amount of Expansion of Sunlight at the Earth's Mean Orbit (46,157 Times) and the Intensity of Sunlight obtained by the Earth (1,365 Wm-2) are perfectly synchronized, and there is no time delay in this phenomenon. Therefore, speed of a Laser beam does not apply to natural light. For more information please contact E-mail ID: astrophysicist.cmvijay1969@gmail.com.

Sep 21, 2015
Light from the Sun does not take eight minutes

But did you define the energy of particles emitted, two different things. The particles may have an unknown speed, i.e. type of emission, and the wave front from the particle is different from the particle emitter. Anyway, you might need a special spectrum and polarizer to define a single event. Best would be to define the single frequency and single polarization first and how possibly manifested, not to mention the single frequency and multi-polar. So, no, we will need a little more work to define precision! The "electron", i.e. the negative pole and the "proton", the positive pole create a given response for certain types of atoms and transitions. I don't think we have properly defined these fields other than a quantum mechanical perspective, not a true simulation as the "point" of sound theory.

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