Speed of light

The speed of light in vacuum is held to be constant at 299,792,458 m/s (186,282.397 miles per second). Designated by the symbol "c" (for "constant"), it is a fundamental quantity of the universe. According to special relativity it is the universe's speed limit and it is part of the relation between mass and energy:

$$\,\!E = mc^2$$

Some have proposed that the speed of light has decayed since the Creation. While this theory opened the door to scientific solutions to the distant starlight problem, it is not generally accepted by creation scientists.

One-Way Speed of Light
Jason Lisle proposed the Anisotropic Synchrony Convention which provides for the speed of light to be variable depending upon the location of the observer, which will always be on Earth.

Sagnac proved that light travels at different speeds depending on its direction and its proximity to the center of Earth's gravity, lending weight to the Anisotropic convention.

The one-way speed of light has never been measured. Every known measurement of the speed of light includes reflecting it from another surface. This necessarily changes the nature of light, as it can only be the average of the outbound and inbound leg. Additionally, all electronic means to measure the speed of light cannot themselves operate at the speed of light. This introduces error and constraint into the measurement. If we attempt to embed a signal into a light beam to synchronize two clocks at a distance, the time it takes to both create and to interpret the signal introduce another constraint. In fact, any introduction of a measurement mechanism necessarily constrains the measurement because no measurement mechanism can operate at the speed of light.

Einstein understood the primary paradox of the speed of light, as evidenced by the theory of black holes. A black hole's gravity is so strong that light cannot reach escape velocity. However, gravity can only act in this manner between bodies with mass, which necessarily means that photons have mass. Physicists generally do not accept the notion that photons have mass. If they do not, they would be able to escape a black hole, and it would not be black after all. However, if the photon has mass, then it is a particle with mass traveling at the speed of light. For such particles, time stands still. There is no duration between their departure (from an emitting source) and their destination. Essentially departure and arrival are instantaneous. If this is the case with a photon, then there is no such thing as a light-year in space, and the age of the Cosmos cannot be determined using light as a basis. Moreover, the speed of light is a function of distance and duration: speed = distance/time. However, Einstein asserted that time is relative. If this is true then the speed of light is also relative and cannot be constant.

To resolve this paradox, Einstein side-stepped it by stipulating that the speed of light is constant without ever proving it.

Whenever scientists encounter particle behaviors that defy the speed of light, such as the propensity of particles to instantly share behaviors even across vast distances (e.g. Quantum Entanglement) they still hold to the notion that the speed of light is constant, eliciting the strangest explanations, including the idea that all particles in the universe are connected to all other particles through wormholes. Such oddball theories are the simplest evidence that the "constant" speed of light has been accepted as a reality rather than a stipulation for mathematical purposes.

History
Albert A. Michelson is credited with developing the method for the definitive measurement of the speed of light. In 1902 he published his classic paper on the speed of light, and in 1907 was awarded the Nobel Prize in Physics for this work. Michelson also proposed the standardization of the international unit of length, the meter, using specified wavelengths of light rather than an artifact. For decades the scientific community used Michelson's standardization method, but finally decided to define the SI unit of length according to the speed of light. Today one meter is defined as exactly 1/299,792,458 of the distance that a beam of light travels in one second.

Many scientists in the past have speculated about possible changes in the values of one or more physical constants and its implications. These speculations were not always greeted with enthusiasm from the scientific community because the implications of any variation in any constant are enormous: it would introduce changes at astronomical levels in the very fiber of the Universe. Yet the idea never totally died out and was never totally suppressed.

Glenn Morton was one of the first persons to put forth a concrete and testable model. He started not from changing fundamental constants, but from another angle. Soon Barry Setterfield came forward with his proposal of variation in the velocity of light. His initial proposal went through several revisions and modifications and creationist publications quoted him widely. Some secular publications also used the information, but the general response was to resist his proposals.

Johnson C. Philip from India put forth the same idea in a broader way in 1982 and did some work with the Physics department of Jiwaji University in India. However, he had to abandon the work in 1984 due to the resistance of some non creationist professors.

The proposal remains promising, and much work can be done. The resistance remains, especially from non creationists. However, the topic might find a revival, now that the secular community has started to consider the idea of changing fundamental constants.

Practical uses
The speed of light has been used to calculate the distance of supernova 1987A from earth with great accuracy, based on observing the time taken for its light to illuminate the Large Magellanic Cloud. It is the standard method for calculating the distance to nearby galaxies.

The part of the SN1987A ring perpendicular to the explosion center (as seen from us) was observed to light up about 8 months after the explosion. The light that took a detour via the ring to us was always a ring radius behind the direct light regardless of the speed of light that prevailed during the trip. The ring radius could be calculated to these 8 months times the speed of light as applied to the year 1987, when the measurement was made. Thus it is not of this observation to deduce if the light has had any different speed before 1987.

The notion of c-decay is currently out of favor even among creationists. Two models for the creation of the universe, i.e. white hole cosmology and cosmological relativity, both assume a constant value of c.

The Anisotropic Synchrony Convention holds for a variable value for c, and likewise provides for c to be relative to the speed of the emitting object. Anisotropism is the actual de-facto convention for Scripture, as God describes things from a human's-eye point-of-view. Even Christ said he would use earthly things to describe heavenly things. The human point-of-view is integrated to the Anisotropic convention, providing for the instantaneous arrival of distant starlight as well as explain local measurement in terms of time dilation.