The Speed of Light is Not Constant

[Aqueous Id]

It is not cynicism to point out that some things are more-or-less extrapolations and some things are more-or-less observations.

I also tend to think the phrase "only indirect observations" conveys a cynical attitude, but extrapolations would be a more objective complaint. I know my GPS corroborates both SR and GR everytime it gives me an accurate fix, as well as the constancy of c in all frames. Is that indirect/extrapolation or direct/observation?

 

[PhysBang]

I also tend to think the phrase "only indirect observations" conveys a cynical attitude, but extrapolations would be a more objective complaint. I know my GPS corroborates both SR and GR everytime it gives me an accurate fix, as well as the constancy of c in all frames. Is that indirect/extrapolation or direct/observation?

As far as the constancy of c in all frames, that would be an indirect observation.

So much of the advances of contemporary physics are indirect observations. I do not find it cynical to observe this. Rather, I am amazed at the ingenuity and care that go into the projects that deliver information and evidence in the face of the challenges facing the observations.

 

[danshawen]

This looks like a fun thread. I totally agree with everything that "valued senior member" has said. As GR deals with accelerated reference frames, no one expects that the speed of light is constant (or even in a straight line) in the presence of large gravitating bodies.

Now apply GR to the expanding space at the cosmological fringes of the known universe recently discovered from an analysis of type 1a supernovae. The expansion there is accelerating exactly as it would do in the vicinity of a large gravitating body, so what happens to light that is propagating there? Does it bend? Which direction? Is the observed curvature due to dark energy pushing things further out by applying a force from within, or could the cause be some force that is already familiar to us? Apply GR's principle of equivalence.

 

[danshawen]

It's no coincidence that Stephen Hawking publicly voiced second thoughts about the event horizons of black holes being abrupt and discontinuous with normal space shortly after the discovery of the Higgs boson. The event horizon would continue to have virtual particles, including the Higgs. If it did not, a black hole could have NO INERTIAL MASS at all. The Higgs mechanism itself would be slowed down, of course, owing to the sum of its interactions with the total mass of the singularity. The Higgs mechanism is the cause of time as we perceive it on our scale, but don't expect to be able to show that with any of the math associated with the current Standard Model. But given that we know that much, it's no wonder that GR needed to explain gravitation not in terms of mass, but in terms of the curvature of space-time. Gravity derives of interactions of matter with space-time, even if we do not yet have the math to show how it derives from quantum scales. This also explains the riddle of why gravity is the one force that can "escape" or be transmitted through the event horizon of a black hole.

 

[river]

.
Wouldn't different frequences of light interfer with each other ? And wouldn't light of the same frequency push against each other ?

 

[danshawen]

"Wouldn't different frequences of light interfere with each other ?

Yes, light of different frequencies would interfere with each other in the event horizon of a black hole, but this would not avail the energy to escape. Even light perpendicular to the EH could not. This is one reason our ideas about accelerating energy need revision. It's been very difficult to get this across, but is only vaguely related to this thread.

And wouldn't light of the same frequency push against each other ?"

The photon is a boson and is the force carrier for EM interactions, but the flow of time (not 'speed of light') anywhere in the universe is related to whether it is near a gravitating body or not, the activity going on in the various fields and virtual particles and energy of the vacuum. Light 'of the same frequency' strictly speaking, doesn't exist anywhere in the universe. This is a break with other quantum identity rules, and it is no accident.

 

[river]

"Wouldn't different frequences of light interfere with each other ?

Yes, light of different frequencies would interfere with each other in the event horizon of a black hole, but this would not avail the energy to escape. Even light perpendicular to the EH could not. This is one reason our ideas about accelerating energy need revision. It's been very difficult to get this across, but is only vaguely related to this thread.

And wouldn't light of the same frequency push against each other ?"

The photon is a boson and is the force carrier for EM interactions, but the flow of time (not 'speed of light') anywhere in the universe is related to whether it is near a gravitating body or not, the activity going on in the various fields and virtual particles and energy of the vacuum. Light 'of the same frequency' strictly speaking, doesn't exist anywhere in the universe. This is a break with other quantum identity rules, and it is no accident.

So what are you saying , inotherwords

 

[paddoboy]

This also explains the riddle of why gravity is the one force that can "escape" or be transmitted through the event horizon of a black hole.

The gravity from a BH is in the main a fossil field from the star from whence the BH formed.
Plus of course gravity is nonlinear.

 

[paddoboy]

This looks like a fun thread. I totally agree with everything that "valued senior member" has said. As GR deals with accelerated reference frames, no one expects that the speed of light is constant (or even in a straight line) in the presence of large gravitating bodies.

The speed of light, "c" is the speed of light in a vacuum, and is a universal constant.

The following link outlines all possible scenarios regarding the above fundamental fact.
http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/speed_of_light.html

 

[OnlyMe]

Without comment on the discussion as a whole. Rather in consideration only of the implications of the quote below...

The gravity from a BH is in the main a fossil field from the star from whence the BH formed.
Plus of course gravity is nonlinear.

If changes in a gravitational field propagate at the speed of light, the gravitational field of a black hole could not be a fossil field, as within that context the field outside the event horizon, absent the influence of the mass within the event horizon, would disparate at the speed of light.

There is likely a great deal more that we do not know about the fundamental character of matter within an event horizon, as well as a clear and consistent understanding of the fundamental mechanism(s) we experience as gravity.

However, we have no evidence that suggests, that whatever mass is within the event horizon of a black hole, is not dynamically associated with the gravitational field of the black hole.., outside the event horizon. In fact from everything we can experimentally confirm about the kinematics of a gravitational field, the mass of a black hole must be, again.., a dynamic component of the field as a whole.

One cannot dismiss the mass of a black hole when contemplating the character of the gravitational field of the black hole. And an event horizon cannot, within the context of our current experience of gravitation, represent some barrier that separates the mass responsible for the gravitational field, from the field itself.

 

[Dr_Toad]

So what are you saying , inotherwords

Bosons may occupy the same state, so why would photons of the same frequency, or even another frequency, 'push' each other once they're in the far field? Of course there may be exceptions, or I could just be wrong...

 

[paddoboy]

If changes in a gravitational field propagate at the speed of light, the gravitational field of a black hole could not be a fossil field, as within that context the field outside the event horizon, absent the influence of the mass within the event horizon, would disparate at the speed of light.

BH's are formed from stars. The gravitational field is already there. It is a fossil field. Once the BH is formed, the curvature of the spacetime out to the EH changes criticality, and the rest of the field, is that from the original star and its mass.

 

[Beaconator]

Bosons may occupy the same state, so why would photons of the same frequency, or even another frequency, 'push' each other once they're in the far field? Of course there may be exceptions, or I could just be wrong...

There is a difference between a logical linear photon frequency and a spherical one imposed by wave particle duality. While an observer might see a push in its visual from two photons it is just an interference of two spherical energy fields which yields a change in the trajectory of the overall summation of photon energy.

If you imagine two spheres expanding outward from two different sources you will discover that at the point the two waves hit the opposite source the interference conforms with the Pythagorean theorem. Yet after it would appear as the two are pushing each other faster than than the linear trajectory although the formal wave front is in parallel line with both spheres.

 

[Dr_Toad]

I'm sorry, that makes no sense to me. Perhaps it isn't coherent?

 

[Farsight]

The speed of light, "c" is the speed of light in a vacuum, and is a universal constant.

The following link outlines all possible scenarios regarding the above fundamental fact.
http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/speed_of_light.html

This Baez article says this:

"Einstein talked about the speed of light changing in his new theory. In his 1920 book "Relativity: the special and general theory" he wrote: "... according to the general theory of relativity, the law of the constancy of the velocity of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of relativity [...] cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity [Einstein means speed here] of propagation of light varies with position." This difference in speeds is precisely that referred to above by ceiling and floor observers".

The speed of light is not actually a universal constant.

 

[krash661]

This Baez article says this:

"Einstein talked about the speed of light changing in his new theory. In his 1920 book "Relativity: the special and general theory" he wrote: "... according to the general theory of relativity, the law of the constancy of the velocity of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of relativity [...] cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity [Einstein means speed here] of propagation of light varies with position." This difference in speeds is precisely that referred to above by ceiling and floor observers".

The speed of light is not actually a universal constant.

it appears speed and velocity are being used as the same entity by the poster here.

my favorite misconception here is this incorrect personal opinion,
" [Einstein means speed here] ".
no. einstein means exactly what words he chose to use.
simple.
and this quote shows exactly that einstein clearly stating that speed does not change , it's path changes.

there's an obvious attempt here to manipulate what is stated by einstein.

 

[Farsight]

There isn't, krash. You can tell this if you note the context, where Einstein talks about the SR postulate, which was the constant speed of light. All the more so when you go back to the original German version, which features the word Geschwindigkeit, which means speed. Einstein wasn't talking about a velocity changing in the vector sense. He wasn't saying "light curves because it changes direction". That's a tautological nonsense. He was saying light curves because the speed of light varies with position. It curves like a car veers when it encounters mud at the side of the road. Like the way you steer a tank. Slow down the tank track on the left, and the tank turns left. Have a read of Ned Wright’s Deflection and Delay of Light. Note this: "In a very real sense, the delay experienced by light passing a massive object is responsible for the deflection of the light”. Light doesn’t curve because it curves, and it doesn’t curve because spacetime is curved. Einstein never said that. It curves because the speed of light varies with position. That's what Einstein said. it curves like sonar waves curve. Like this:

Image credit Ned Wright, see http://www.astro.ucla.edu/~wright/deflection-delay.html

 

[krash661]

There isn't, krash. You can tell this if you note the context

i'm going to repeat what i wrote in that other topic,

well, instead of incorrectly " interpreting ",
try to actually understand words that are used with this theory.

interpretation is a result of not understanding words or meanings that were used.
so it's done to attempt understanding using other words or meanings to fit the individuals mind.
when done by the individual that does not understand to begin with,
it always leads to continuous misunderstanding ,
which is exactly the situation.

interpretation,
every time i see that word it's nauseating,
it's the same as " short cuts " in mathematics

not only that, but the little image submitted, clearly shows it's the path that changes.
do you realize the rest of your post clearly states it's the path that changes ?

correlate path and position.
simple.

 

[krash661]

post #697
are typical misconceptions by those who do not even touch theorems.
which is where the answer to this topic is.

 

[Beaconator]

I'm sorry, that makes no sense to me. Perhaps it isn't coherent?

Perhaps not, but many other things in this thread follow the same logic of incoherence.

Now if someone had said the velocity of light was not constant all we would have to do would be point in a different direction to validate that statement.