If the Speed of Light changed, would we even notice it.

[Qfwfq]

I agree that theology and notions such as 'divine' are a bit out of the point in scientific discourse. Epistemology and even Metaphysics are more in scope.

[paultrr]

I agree myself. If you are looking for some absolute theory of everything that explains the origin of everything at the current time we simply do not have that type of fully worked out theory. There are a few paths towards that eventual theory which is what guys like Smolin are trying to point out.

 

One bit more on the issue of the constancy of C. The quantum theory of atoms tells us that these frequencies and wavelengths depend chiefly on the values of Planck's constant, the electronic charge, and the masses of the electron and nucleons, as well as on the speed of light. It is a basic postulate of the theory of relativity that the speed of light is constant. This can be broken down into two parts:

 

• The speed of light is independent of the motion of the observer.

 

• The speed of light does not vary with time or place.

 

Yet, here we have indirect evidence that this may not be the case being raised on many fronts including the Pioneer Anomaly and Cahill’s mention of the non-null M&M experiments. In the first case, both of these observational and experimental results would indicate that the speed of light is not independent of the motion of the observer. Secondly, the speed of light would seem to vary with at least place. However, it’s also possible it varies with time then. This would all be true if that data holds up unless some mechanism to account for such can be derived.

 

Going back to GR, In the 1920 book "Relativity: the special and general theory" Einstein 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 of propagation of light varies with position. In general relativity, the appropriate generalization is that the speed of light is constant in any freely falling reference frame (in a region small enough that tidal effects can be neglected). In this passage, Einstein is not talking about a freely falling frame, but rather about a frame at rest relative to a source of gravity. In such a frame, the speed of light can differ from c, basically because of the effect of spacetime curvature on clocks and rulers.

 

Einstein's second postulate is equivalent to setting S(x’)=-v/c^2, so that one obtains the well known Lorentz transformation equations. But the original and follow-up M&M experiments were designed is such a way that the Null results rather established Lorentz’s proposal of them in the first place. The position of the earth, if we consider the Sun as being the strongest source of gravity in the local region, while in orbit is still relatively at rest to that source of gravity. As mentioned before in such a frame, as Einstein understood it the speed of light can differ from the vacuum value of C to begin with. What this implies is that locally spacetime is not flat. In a curved situation, as Einstein put it, “A curvature of rays of light can only take place when the velocity of propagation of light varies with position”. Closer to the source or in its direction that velocity of propagation should be higher than far away from that source or outward from the source which is exactly what both the Null results of the M&M experiments show and the Pioneer data.

That brings one back to what I’ve mentioned before that if one considers spacetime locally as some small section of the global picture of spacetime the fact that locally spacetime is not flat has implications that globally spacetime is not flat either. Going back to Einstein’s own words, A curvature of rays of light can only take place when the velocity of propagation of light varies with position. The implication given that we exist in a universe where there are many sources to begin with of gravity is that C will not always be constant in every frame of reference. One evidence of this would be found in the Pioneer anomaly and in something a recent author by the name of Cahill mentions that actually the original M&M experiments and all the follow-ups do not actually yield a fully null result( see: Lanl-physics/0501051).

 

I might also mention that the WMAP data on the CMB while yielding an overall value of 1 for omega has to be understood on what that 1 value actually shows us. Regular matter and dark matter make up about 75% of that value. Its regular matter and dark matter that give us the overall amount of gravity producing energy in the cosmos. Being that the value of both is below one spacetime is curved into a saddle format. The extra component of that 1 value of omega, exotic energy, only increases the effect of saddle shaped geometry by increasing the rate of expansion with time. What this accelerated expansion amounts to is a global dilution of the curvature of rays of light so that eventually what one observes is a universe that appears more and more flat with time. But that dilution also means that one is left with regions of local spacetime where local curvature can appear even more divergent from a flat case when it comes to comparing frames of reference. In such a case, since the expansion varies with time then under certain circumstance following Einstein’s own accounts of this C can be considered to vary with time as well as position and place. Basically, locally one might not always get the same result as one tends to get from the global picture.

[paultrr]

The study of the CMB has been at times raised as setting limits on variance of C. As concerns the fine structure constant the limits would be <1.2X10^-8, the electron proton mass ratio sets it at around 9X10^-5 under BM modeling. But if the CMB's dark energy component tends to modify our observations with its pushing towards the flat case then these constraints may or may not actually hold, especially when it comes to local cases of measurment versus global ones. Here is where I see reason for difference in some of those reported figures that seem to imply C has slowed down after the inflation period or that the fine structure constant might have changed. One must first determine how much the dark energy out there effects our ability to properly measure such. For that we need more than one set of measuring observations which is where the debate is at during the present time.

[WebFeet]

One must first determine how much the dark energy out there effects our ability to properly measure such. For that we need more than one set of measuring observations which is where the debate is at during the present time.

Dark Energy is a proposed solution to account for gravitational forces that exceed those calculated for the available mass.

 

The available options open are :-

1. The amount of mass is greater than has been observed. - Dark Energy/Matter

2. The theories we use are not correct.

 

We have anomolies within our solar system that point to a lack of understanding of the mechanics, Pioneer to mention 2 of them. Maybe once we understand those problems closer to home, be they dark forces or variable light speed or something else, we will be in a better position to try to determine what goes on in the rest of the Universe.

[C1ay]

There must be a valid method for the construction of SpaceTime...

 

Why? Perhaps space and time have existed for eternity. Does everything absolutely have to have a beginning?

[WebFeet]

Why? Perhaps space and time have existed for eternity. Does everything absolutely have to have a beginning?

For something not to have a beginning, it would also follow that it should not have an end. If this were a straight line, then it would have to have had a start point. One way something can have neither a beginning or and end would be if it were circular.

 

That would make mean that entity lasts only for one complete cycle, after which, time would be reset.

 

If the model is not circular, then it must have a start point.

[paultrr]

One of the biggest pushes in modern cosmology and physics is to avoid the singularity of time in the first place. As a result some models have one and others do not. In all the models being looked at even if there is a singularity at the begining the first cause of creation is nature and natural process to begin with.

[C1ay]

For something not to have a beginning, it would also follow that it should not have an end. If this were a straight line, then it would have to have had a start point. One way something can have neither a beginning or and end would be if it were circular.

 

That would make mean that entity lasts only for one complete cycle, after which, time would be reset.

 

If the model is not circular, then it must have a start point.

 

An infinite straight line does not have to have a start point or an end. It is not circular either or it wouldn't be a straight line.

[WebFeet]

An infinite straight line does not have to have a start point or an end. It is not circular either or it wouldn't be a straight line.

If the line is infinitely long, then there is no way you can determine wether it is straight or not and whether one end loops round, eventually, to meet the other.

 

Straight lines can become circles when encountering curved spacetime, without ceasing to be straight lines.

 

IMHO, unless something is circular, it must have a starting point. If there was something prior to the starting point, then you've not looked back far enough.

[C1ay]

If the line is infinitely long, then there is no way you can determine wether it is straight or not and whether one end loops round, eventually, to meet the other..

 

What does it matter if you can determine whether it is straight or not?

 

IMHO, unless something is circular, it must have a starting point. If there was something prior to the starting point, then you've not looked back far enough.

 

That's just a way of saying that you don't believe in infinity.

[WebFeet]

What does it matter if you can determine whether it is straight or not?

The point is that you can't. You have no way of knowing if you're still moving at 180 degrees away from the beginning of the line or towards it. The only part of the line that you can preceive is the part in front and behind you. For all you know you line could be circular.

That's just a way of saying that you don't believe in infinity.

Even inifinte numbers have to start at Zero+.

Infinite, by definition, means without boundary or limit. Your use of the term is in relation to the age of the Universe, or at least SpaceTime.

If this is true, then SpaceTime has always been. We have enough trouble dealing with this incarnation of our Universe and how old it is, let alone the concept thatSpaceTime has always been.

 

For SpaceTime to have always existed would require either Divine intervention or Faith, neither of which have a basis in science.

[paultrr]

I can partly see where the problem with infinity comes into play. To be honest, usually within physics the determination or finding from the math involved of an infinity tends to be taken as evidence something is missing from the equation. We got infinite solutions out of the standard model before we employed renormalization as a means to reduce those answers down to something more correct. The general thrust within cosmology to get around the singularity of time stems from a desire to better understand the instant of creation itself which by the math at present is impossible because the energy appears to be infinite at such point. But the general concept that time could in one form or another always existed is not what to most of us poses a problem. Time as being infinite and the existance period over which this universe has existed are not exclusive at all. The period of time over which the universe we exist in has existed could simply be an extension of that more infinite time itself. Loops in time, like some of the more cycle like models of cosmology are also looked at by such people as Richard Gott(See: Time Travel in Einstein's Universe). None of these models are fully ruled out by any of the data we have at present basically because we really do not have a complete picture of everything yet.

 

I think the thing to remember is people like myself and others who are part of the VSL discourse are simply after probing the bounds of our knowledge of this universe to try and discover more of a complete picture. Its also rather human nature to try and break through barriers of which C is perhaps the greatest barrier there is.

[C1ay]

Even inifinte numbers have to start at Zero+.

Infinite, by definition, means without boundary or limit. Your use of the term is in relation to the age of the Universe, or at least SpaceTime.

If this is true, then SpaceTime has always been. We have enough trouble dealing with this incarnation of our Universe and how old it is, let alone the concept thatSpaceTime has always been.

 

For SpaceTime to have always existed would require either Divine intervention or Faith, neither of which have a basis in science.

 

The number line runs both ways, it does not start at zero. I have no trouble dealing with the concept that time has always existed and will always exist. IMO, the space in our universe is just a subset in an infinite space. For me it requires no divine intervention. It is a logical deduction for me that something lies beyond the boundary of the event horizon of our universe.

 

I believe it is faith that leads those to believe that our universe is all that there is and that there can be nothing else or nothing more. To conclusively rule out possibilities without proof conflicts with my belief in open-mindedness.

[WebFeet]

The number line runs both ways, it does not start at zero. I have no trouble dealing with the concept that time has always existed and will always exist. IMO, the space in our universe is just a subset in an infinite space. For me it requires no divine intervention. It is a logical deduction for me that something lies beyond the boundary of the event horizon of our universe.

The only way you could make such a logical deduction would be through experimental evidence, such as the energy from the initial event bouncing back from the boundary and being detected. I'm not aware of such evidence.

This means that you are basing your reasoning not on evidence, but on instinct.

There is no logical process to summize that there is anything else other than what we can detect. To assume the existance of something is pure speculation.

 

I'm not saying that I don't think there's something beyond the boundary, but that's just it, I think. I have no proof or evidence.

[pgrmdave]

I don't know that I agree, WebFeet. I think that the question becomes whether or not it is logical for there to be a "beginning" of time. Time is a measurement of events, so, the beginning of time would be the first event. However, we don't know of any self-starting events, every event in our experiance has a cause, so it is only logical to see that time can stretch infinitely back.

[WebFeet]

I don't know that I agree, WebFeet. I think that the question becomes whether or not it is logical for there to be a "beginning" of time. Time is a measurement of events, so, the beginning of time would be the first event. However, we don't know of any self-starting events, every event in our experiance has a cause, so it is only logical to see that time can stretch infinitely back.

Quite a paradox :friday:

 

Time, after all, is only a measurement. It is sequence and duration.

In this respect it is no different from length or height. If there is a lack of the 3 primary dimensions, then there is no length or height. So if there is a lack of duration, then there cannot be any time.

 

All you are left with is sequence. There is no reason why time should exist beyond our Universe. After all it is measurement determined by those things on the inside.

 

After the Big Bang, you have the Big Crunch and then everything starts over again, from Tzero.

[Fishteacher73]

I think one problem is our defining of time. Time is a erelatively linear construct. Mathematically it appears to have an origin at zero. I think that zero is more an asymptote on the timeline. Most of the equations breakdown when you look at t=0. This does not mean that there could not be negative time; just that 0 time does ot compute.