The Speed of Light

 The Speed of Light - Why is it What it Is?

Perhaps a better way to ask this question is where does this ultimate speed limit come from? Funny you should ask. The speed of light comes from the field that defines the electromagnetic and it gets its definition from the electric field strength and strength of the magnetic interaction.

Where..

- ∈₀ = F_e / Q_c = 8.854187817*10^(-12) Coul²/joule*m, where &isin₀ is the electric field strength or otherwise known as the permittivity of free space, which is the ratio of force on an electron to the charge of the electron, and Q_c is the charge in coulombs. Permittivity the ability of a substance to store electrical energy in an electric field.

- µ₀, the strength of the magnetic interaction, is 4 * π * 10^-7 N/A² , 1 Ampere is 6.241 10¹⁸ electrons per second (1 coulomb per second), the permeability of free space or otherwise known as the magnetic constant, or is 1.25663706 × 10^-6 (kg⋅m)/(s²⋅A²). Permeability is the measure of magnetization that a material obtains in response to an applied magnetic field.

The speed of light can now be calculated c = 1 / √(∈₀ * μ₀)=

2.998633804661277*10⁸ m/s

If either of these numbers, ∈₀ or µ₀, were to change then so would the speed of light.

Why does this formula give the speed of light? Let’s study it; ratio of force to charge of an electron multiplied by the strength of the magnetic interaction then take the square root of that and invert it. Both Ɛ_o and µ₀ are vectors, meaning they have direction, so they have conjugate values, and both are constants making c a constant.

But alas light is a boson of the electromagnetic field and particles mostly are electrical in nature.

More on the Speed of Light

Albert Einstein postulated that the speed of light with respect to any inertial frame is independent of the motion of the light source and explored the consequences of that postulate by deriving the special theory of relativity and showing that the parameter c had relevance outside of the context of light and electromagnetism. After centuries of measurements, the speed of light was known to be 299,792,458 m/s with a measurement uncertainty of 4 parts per billion.

The photon is not the only particle that is subject to the speed limitation, anything including gravity cannot exceed this limitation.

Why?

To begin to answer this question see how it is derived as shown above. So, what makes the speed of light so important, so limiting of everything?

How was it Derived

The speed of light was originally measured by the use of astronomy. It was indirectly calculated from the measurement of the position of the moons orbiting Jupiter at different positions of the orbit of Jupiter around the sun. The measurements were done of the position of the moons when Jupiter was closer to the Earth and when it was farther away. The phase or relative position of the moon was noticed at different positions than originally expected had light been instantaneous. Ole Romer first demonstrated in 1676 that light travelled at a finite speed by studying the apparent motion of Jupiter's moon Io.

But even though we have written this simple linear equation with the dependent variable of y it can also be solved for x by a simple rearrangement of the terms therefore turning x from a cause and making x an effect. Most cause and effects are not reversible, they are asymmetric. If I develop a mathematical relationship that says y = mx + b, I can't always apply the formula x = (y - b) / m and say that y caused x. I could state what x would be for a given value of y but I could not necessarily say that a given value of y would cause x to take on the calculated value of x. The two variables are symmetric and intertwined. In the physical world this form of role switching, it doesn’t seem often to take place. This form may not always represent true cause and effect as it can be re-written without changing the meaning. Most effects are a one-way street.

Another way to measure the speed of light is by measuring its wavelength. You can do this with a home microwave oven. The product of the frequency and wavelength of light (microwave light in this case) will give the speed of light.

c = v * λ

v is often a symbol used to define frequency and lambda (λ) the wavelength.

The wavelength is determined by taking advantage of the cavity used for resonance and the frequency is known by the colour of the light. This household demonstration of this technique is possible, food such as marshmallows or margarine. Remove the turntable so that the food does not move. The food will cook the fastest at the antinodes (the points at which the wave amplitude is the greatest), where it will begin to melt. The distance between two such spots is half the wavelength of the microwaves; by measuring this distance and multiplying the wavelength by the microwave frequency (usually displayed on the back of the oven, typically 2450 MHz), the value of c can be calculated from this measurement. Click the link below to see a video of the measurement.

An argument in Support of Luminiferous Aether

“It appears that the universe is filled with a luminiferous aether, the particles are in contact, and they move like great sheets or in tandem. For this reason, the drift of the aether has no effect on the direction of the propagation of light in the Michelson-Morley experiment.”

The Michelson-Morley experiment was done with interferometry measuring the speed of light, or more accurately the difference in the speed of light, in perpendicular directions where they found no measurable difference. The experiment originally designed by Michelson using a source of light and a half-silvered mirror split the light at right angles and then after they traveled through a distance re-aligned them and had there been a difference fringes would have been visible due to phase shifting of the light. Morley improved on the experiment by making the light travel much farther by bouncing off multiple times. The experiment was repeated numerous times by different scientists with the same conclusions. A newer version of the experiment was done using an optical resonator with confirmation of no aether wind down to 10-17. The only way this observation could make sense with aether is if the aether was being dragged by the earth and in motion with it always regardless of its orbital position and its spin. The Lorentz factor was eventually determined from this experiment.

Also, the speed of light is constant relative to the observer, and this has been measured. If there was aether, then as the observer moves opposite direction of the light then it would measure a higher than light speed. If the observer moved away from the light the speed would appear to be slower than c. This has not been demonstrated. The speed of light is constant regardless of the relative speed of the observer though the frequency does shift.

The speed of light in a vacuum stands at “exactly 299,792,458 metres per second “. The reason today we can put an exact figure on it is because the speed of light in a vacuum is a universal constant that has been measured with lasers; and when an experiment involves lasers, it is hard to argue with the results.

Here is an interesting article on the speed of light found in Forbes published November 7th 2016

Forbes link 'How do we meausre the speed of light'>

It can also be calculated by using the field that defines the electromagnetic and it gets its definition from the electric field strength and strength of the magnetic interaction as mentioned in an earlier section of this document.

Why are all objects limited to this speed even if they don’t interact with the electromagnetic field?

The speed of all information is limited by c and so are the speeds of gravity waves plus the propagation of the strong and weak nuclear forces. Why is that?

We seem to live not only on the surface of a planet but all this stuff we see in our universe lives on a surface called space-time. This concept has its roots in relativity and its special theory. It states that no signal can cause an effect outside the source light cone, the cone that is created by the speed of light and time. If anything could violate this principle of relativistic causality then it would lead to paradoxes, such an effect preceding its cause. The paradox would exist because to be outside of the light cone means that the object is moving backwards in time.

In special relativity, a light cone, or as I like to call it 'Causality Cone' is the surface describing the temporal evolution of a flash of light in Minkowski space-time. This can be visualized in 3D-space if the two horizontal axes are chosen to be spatial dimensions, while the vertical axis is time.

The light cone is constructed as follows. Taking as event p a flash of light (light pulse) at time t = 0, all events that can be reached by this pulse from p form the future light cone of p, while those events that can send a light pulse to p form the past light cone of p.

Arvin Ash does a great description of this in his video.

Why is there a speed limit to causality?

Perhaps time is just as much space as space is time. Configuration space, as Julian Barbour describes it, has more than the three dimensions which we are familiar with. Imagine instead of one set of configurations of particles but a continuous set of configurations of those particles. Much like the two-dimensional film of a movie sliced into 25 millisecond time slices, giving the third-dimension time, as we see it, three-dimensional space has another axis which it is configured on, and each position of every particle is mapped to it. This does not answer the question.

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Imagine that each particle is mapped to every probable place that it could exist. Every probable place is defined by Ψ(Psi), yes Schrodinger. This would give another axis to space-time; this completes configuration space.