What are the evidences that speed of light is constant all over the universe? Is it the same value even in places in universe which dark energy is occupied?
In general I would say no. But it depends on the way you measure it. If you measure the instantaneous speed in a neighborhood of the emitting source the speed of light is always constant. But if you measure the speed of light between two events apart from you in a curved space-time, the speed of light is not constant any more.
Yes the speed of light will be observed as a constant. Precisely because the individual quantum components that make up dark energy also travel at the speed of light.
Andrew thanks for your answer, I want to know more clearly the answer of this question that assume we travel to another planet vastly far from earth but still in our universe and do a test to measure speed of light (by the way with same reference rod and clock as we take it from earth). Do we still measure the same value that we measure on the earth or could be different value?
"The speed of light in empty space, measured in an inertial frame, is c”. That cannot be denied because it is built into the definition of the unit of speed (meters per second). See https://physics.nist.gov/cuu/Units/current.html
An “inertial frame” is a reference system for an unaccelerated observer. Now, in the curved spacetime of General Relativity the inertial frames are not extensive, they can be defined only locally (in a “sufficiently small” region of space for a “sufficiently small” time interval). It remains true that the speed of light, measured in any local inertial frame at any point along the path of a light ray, is c.
However, if the emitter and the receiver of a light ray are widely separated in a curved spacetime, we need to specify the distance between emitter and receiver and the time between emission and reception, and that distance and that time can only be defined arbitrarily, in terms of a chosen coordinate system. The “coordinate speed” is then just a calculated number of no real physical significance because it is dependent on the choice of coordinate system. In general, it will not be equal to c.
Similarly, even in Special Relativity, an accelerated observer measuring the “speed of light” will in general obtain a number different from c, because his reference system (a curvilinear coordinate system) is not an “inertial frame”.
Surely an inertial frame is a concept we have created in order to validate the notion of the 3rd party observer and our desire to affect direct measurement? It has obviously had its uses but as a concept it will be limited by the confines that gave rise to its conception. When we come up against these limitation we develop extensions to the concept as far as its 'meaningful' to do so. Our experiential perception of the world does not work on this basis.
It depends on your choice of coordinates. At any point, the local measurement generally has the same value but over finite distances it is generally not true. Arguably the most obvious illustration of this is Shapiro Delay, see the link.
https://en.wikipedia.org/wiki/Shapiro_delay
The speed of light as I understand is the speed of a propagating electromagnetic wave through a vacuum, alternatively it is the speed at which a massless object travels when unhindered. A ray of light can be 'slowed down' by forcing the light to be absorbed and emitted by the particles it encounters but while it is travelling in a vacuum it will maintain it's speed c.
Since this speed is simply a byproduct of the underlying physics I'd say it's fairly unlikely it would change depending on where you are, in fact this is one of the main assumptions in special and general relativity. That's not to say that if you travelled far enough away that you were back at the beginnings of the universe these laws would still hold, but other than at the extremes of the universe I don't see any reason for this to change.
“…What are the evidences that speed of light is constant all over the universe? Is it the same value even in places in universe which dark energy is occupied?…”
- it seems as something that is not substantively grounded to discuss – how the “dark energy”, if exists, affects on the speed of light. All what seems as essentially grounded is the fact that all all/every material objects [particles, bodies, galaxies…] move in the 4D sub-spacetime of the absolute Matter’s [5]4D Euclidian spacetime only with 4D speeds c [“c” means 4D vector] that have identical absolute values be equal to the standard speed of light. At that all/every objects have momentums P=mc and energies E=Pc=mc2
This “c” value can be measured, since the “restmassless” particles, first of all photons, are created by some impacts with “using” momentums P that have non-zero only 3D components and so such particles move in the 3D space – with the speed of light - only.
From [including] this fundamental fact above follow the all other physical properties of the objects, so if somewhere in the space were some regions, where the speed of light isn’t equal to c, then at observing objects in such regions some physical effects that differ from those that are observed on Earth would be detected. However seems on billions light years distances the physics is practically the same as on Earth; so we have some right to conclude that the speed of light everywhere in the space is the same.
On the other hand there are seems essential evidences that “the space is expanding”, including “because of some dark energy”. Such possibility indeed cannot be prohibited, besides that the space cannot expand fundamentally, there can be only some changes in Matter fundamental structure [very probably of Matter’s “Aether”] that are observed as a “space expansion”. This phenomenon isn’t understandable now enough to make some not too questionable inferences, but for physics on at least hundreds of thousands of temporal and light years corresponding possible effects are inessential.
More see https://www.researchgate.net/publication/273777630_The_Informational_Conception_and_Basic_Physics ; and, relating first of all to what expansion could be at the Beginning, in https://www.researchgate.net/publication/260930711_the_Information_as_Absolute , Sec. 6.1.3. “The problem of Beginning and evolution of Universe”
Cheers
Article The Informational Conception and Basic Physics
Article the Information as Absolute
Yes, it is in vacuum. If did not where, all the measurements made of cosmological distances are wrong, CMB, Dark Matter, etc. Also SR and GR (here only the modulus conserve, direction is changed by the presence of matter concentration, gravitational lenses).
I presented a theory where Gravitation is epoch dependent and the topology of the Universe is a lightspeed expanding hypersphere. Below are the Gravitational Law and the cross-section of the Lightspeed expanding hyperspherical universe.
And yes, all measurements of cosmological distances are wrong!
The evidence for this bold statement are two-fold:
Once the distances are corrected to accommodate an epoch dependent G, all SN1a Cosmological Distances (Supernovae Survey Union 2.1) fall into place and match the predictions of my theory (Hypergeometrical Universe Theory HU)
Below is the plot of HU parameterless predictions and corrected SN1a Supernovae distances. Notice that this d(z) is the Cosmological Ruler to be used with all Cosmological distances.
HU d(z) is presented below. You can see that it matches all SN1a distances and that it doesn't have parameters associated with Dark Matter and Dark Energy.
So, Cosmology can be easily explained without the unsupported physics of Dark Matter and Dark Energy.
issuu.com/marcopereira11/docs/huarticle
The second evidence is derived from the SDSS BOSS dataset. This dataset contains 1.3 million galaxies. I used my theory and this d(z) to calculate the current position of all galaxies.
Below I present the CURRENT EPOCH map of the Universe. You certainly notice that there is no stretching of space (unnecessary once SN1a d(z) are corrected). The CURRENT (instantaneous) aspect of the map is the result of the 5D Spacetime nature of the model. The model allows for a Cosmological Time (absolute time) and proper times (projections of this Cosmological Time onto local frames of reference within the hypersurface were we exist).
HU model for motion allows for the projection of past observations onto the current hypersphere.
Once you have the map, you can look perpendicular to the Celestial Coordinates space.
The result is astonishing. One can see a density profile that can only be connected to a slowing rising of acoustic waves. These waves left a footprint as galaxy density profile. they seeded the formation of galaxies.
You can read about HU Big Pop and Many-Bang Cosmogenesis theory here.
https://www.youtube.com/watch?v=r54AQc2BR5c&t=190s
HU d(z) and Maxwell equations, require that Electromagnetic Waves to have a radial velocity equal to c. The tangential velocity varies depending upon the angle of observation. In HU, redshifting is the result of a varying projection of a 4D k-vector onto the local hyperplane. That together with the radial EM velocity equal to c, indicates that the speed of light of redshifted photons is higher than c.
This means that the higher the redshift the faster the speed of that photon (local speed, I emphasize).
Another extraordinary result of HU is that the intensity decay doesn't depend directly upon the 4D Distance (AC distance on the figure below). Instead it depends upon the distance (difference in 4D radius) between two epoch.
The hyperspherical acoustic oscillations show in the SDSS BOSS dataset, clearly indicate the existence of waves along the DISTANCE dimension. This is evidence that General Relativity is incorrect since it is evidence that the Universe is not a 4D Spacetime. The recurrence of acoustic waves along the DISTANCE dimension also rebuts the Big Bang (single explosion within a 4D Spacetime). SN1a HU d(z) matched predictions rebuts Inflation Theory, L-CDM.
So, there is a lot (all) that current Cosmology got wrong.
That said, you can bring water to a horse, but you cannot bring a horse to water.
https://issuu.com/marcopereira11/docs/huarticle
https://www.youtube.com/watch?v=ytuEctnD334
https://www.youtube.com/watch?v=r54AQc2BR5c&t=190s
Dear John Jupe ~
You say “Surely an inertial frame is a concept we have created in order to validate the notion of the 3rd party observer and our desire to affect direct measurement?...”
An “inertial frame” is simply a reference system suitable for recording the observations/measurements of an observer who is not accelerating (ie: according to Newton’s first law, not subjected to an external force).
Having determined and expressed physical laws in that simplest possible kind of reference system, one can extend the findings to other kinds of reference system.
Without a reference system nothing intelligible can be said about physics!
“Is speed of light constant all over the universe and equal to what we measured?”
The principle that physical laws as we know them on Earth are the same throughout the universe is an assumption. Physicists, astronomers and cosmologists make that assumption because they have no other option: it is in principle untestable.
In the International System of Units (SI Units) “one meter” is defined as “the distance light in a vacuum travels in 1/299792458 seconds”. “The speed of light” is then 299792458 meters per second; it is defined to be a constant. It could be different (though still expressed by that same number!...) in different places or at different times only if “one second” here and now were different from “one second” elsewhere and elsewhen. But how could we compare them? Obviously, we cannot! Suppose “one second” were different when the universe was new (or, what amounts to the same thing, at vast distances from us). What would that even mean? “One second” is defined, in SI units, in terms of a particular spectrum frequency of a Cesium atom. In the early stages of the evolution of the Universe THERE WERE NO ATOMS! So what could it possibly mean, to compare the speed of light THEN to the speed of light HERE AND NOW??
"there's speculation, and then there's more speculation, and then there's cosmology" – Michio Kaku
THERE ARE 7 MULTIVERSES, AND IT COULD VERY WELL BE THAT EACH MULTIVERSE HAS ITS OWN PHYSICAL LAWS AND THAT THE VELOCITY OF LIGHT INCREASES AS WE GO TOWARDS THE UPPER VERSES
In my book I postulated that "speed of light is increased equally in all frames of reference" thus speed of light be the same in all frames of reference.
-As the speed of light is increased with time and as the observation process takes time, it will be a difference in speed of light between the observer and the observed body regarding to the distance between them where ∆c= Hubble constant × distance,
-Thus speed of light is relative at observation while it is absolute before observation.
-light is accelerated with 6.9×10-10m/s2
-Acceleration light is relative in moving frames where the acceleration of light is decreased in moving frames with respect to the stationary observer (6.9×10-10m/s2) / (Gamma)
-Wavelength of light is stretched with time as the speed of light in increased with time thus Redshift happen (E=h∆c/∆ λ )
-Time of bodies is dilated at observation even theses bodies are stationary, this occurs as the speed of light at the observed body is less than that at the observer.
-Mass of bodies is increased at observation, the decreasing in speed of light at the observed body is compensated with increasing in mass, thus energy is conserved (E=mc2),,, thus there is no massless particles at observation
-I find other results that are amazing and strange.
Hi Eric,
There are no reference frames in vision. No frames or frames per second. No information structure blur, motion blur or depth of field.
"Without a reference system nothing intelligible can be said about physics!"
What does physics have to say about experiential reality and why can't it get there? Ans: it's total reliance on reference frames as the only reference system. It's this that sets up the 3rd party ontology.
There is nothing wrong with this apart from the fact that it's missing something fundamental about the way we are embedded oil universe. This is likely to be important? It's this that physics can't get its head round deploying only the 3rd party ontology.
This is why we need to model visual awareness to start to articulate what it is that our current approach (in physics) is failing to engage with. We need to say something intelligible about vision and or relationship with the real. Unless physics can get to grips with what's actually involved in us (as complex bio systems) being objective its actually unlikely to say must that is ultimately intelligible?
It won't make sense.
Shahinaz Yousef
Do you care to provide any shred of evidence for this statement?
My answer to this question is the following. There are thing which we can never know for sure. We can never measure the velocity of light in each quarter of the Universe.
What we can do is to assume that the velocity is constant and see how does that classes with observations.
It does not.
Another assumption is that the Gravitational Constant is the same everywhere and in each and every epoch.
It turns out that that clashes with observations. If G were constant, the Universe would have to have suffered stretching, Inflation and all the crazy things you hear.
If you relax that HYPOTHESIS, then it is easy to see that if G were inversely proportional to the age of the Universe, everything would fall in place.
I derived a new Law of Gravitation that is epoch-dependent and uses the correct topology for the Universe - The Universe is a lightspeed expanding hyperspherical hypersurface.
Attached is the correct Law of Gravitation... by correct I mean the correction to General Relativity.
Here is the discovery of an extra spatial dimension:
https://www.quora.com/How-do-two-dimensional-organisms-on-a-sphere-realize-that-they-live-on-a-sphere/answer/Marco-Pereira-1
You can replicate it on your own computer:
https://hypergeometricaluniverse.quora.com/Universe-Trove
and here is the argument for me to correct the Whole Physics:
https://www.quora.com/When-has-physics-been-wrong/answer/Marco-Pereira-1
Dear Vahid,
The velocity value depends on the due unit. In the case when unspecified unit one cannot say of equal that values. The speed of light is independent for inertial coordinate systems, deducing the being had metric for that space. So using of the Riemann pseudo-manifold model is equivalent to the constant of the speed of light at all points. This means that the set of all light cones is a continuous and oriented fiber.
Well, for me, the most appropiate answer is: "we don't know for sure".
However, I think is important to be clear on what concept of "Universe" are you refering to, first. The "Observable Universe" of the Universe as the totality of what exist and the totality of Reality.
For the first one. For the question: " Is speed of light constant all over the Observable Universe". I believe the answer is very likely to be "yes".
Why? because, there is no any reason why this has to be the opposite case. We know, and we fully understand know, that one of the foundation principles of Special Relativity, is that the speed of light has to be a constant, independently of the speed of any reference frame which we may choose to measure it from.
So, if Special Relativity is true, and we believe on the results and predictions of the theory, then, necessarily we must believe in the constancy of the Speed of Light for any fram of reference (moving with constant velocity, in rest, or accelerated), at least in our Observable Universe. We don't have any reason to think that the principles of Special Relativy are only valid in some regions of our Observable Universe, and not valid in other regions of it, far, far away from our vecinity, nor, a reason to think that SR only apllies to a particular scale of lenght, or a particular scales of Energy, or Mass, or acceleration.
Special Relativity is valid for all Lorentz's Transformations, which are the generalization of the Galilean Transformations.
Now, for the second point of view, this is to ask :
Outside our Observable Universe, is the Speed of Light equal to 'c', and constant in all frames of reference ??
Well, normally, with the phrase "Beyond, or, outside of our Observable Universe", what it's understood is: that there could be regions, so apart from the region that we consider as our Observable Universe. So far away, that for all means, the Space-Time between two of these regions are totally and causually separated from each other. There is not, and never will be a causual link between two of these regions. This is often refered as the Multiverse Level I.
Considering this scenraio, I would say: "we don't know" .
There are odds.. I would say that the likelihood that it'll be so (the constancy of the speed of light, and the value of 'c' as it true value), is greater that the opposite case. But maybe the inbalance in the likelihood of both cases isn't much .
The most honest anwser in this scenario is: "no one knows". So, such question lies in the speculative plane, within subject like the Multiverse. But is NOT physics.
and is not just to say this to try avoiding the question,by justifying that is not a physics question. but, even, it doesn't make much sense to think in the answer to this queston (and other like it kind), since it might be never possible to know for sure.
Regards !:)
- Badges
- Science topic