|Speed of light from a flashlight on a bicycle, or on a train, or on any moving container:
Consider a person holding a flashlight inside a train. Most people accept that the light from the flashlight moves at the
speed of light inside the train regardless of the speed or direction of the train. There is no Doppler shift inside the
train. There is Doppler shift outside the train.
Then a person rides a bicycle along side the train. The light is passed from the train passenger to the bicycle rider. The
speed of the flashlight didn't change. Since the speed of light is always shown to be c relative to the earth, the speed
of light from the flashlight must have changed to be c relative to the ground. That must mean the speed of light was
relative and additive to the train and changes to become relative and additive to the moving earth. After all, the earth
is continually accelerating.
This example is consistent with the theory of relativity train experiment that shows the train and the earth are
comparable relative moving frames of reference. The conclusion from this scenario is: 1) If a person has a flashlight
and they are riding inside a moving contained frame, the light moves from the flashlight at the same speed relative to
the frame regardless of the speed of the frame. 2) If light from a flashlight on a moving contained frame is relative to
the frame, it must be additive across frames. It says the speed of light is relative and it also says it is additive.
Suppose the flashlight is on a bicycle inside a large room that is on a large ball. Suppose the large ball is called earth.
Suppose the bicycle inside the room is on the equator and is stationary relative to the surface of the earth. When the
speed of light is measured, it is a constant "c" relative to the flashlight on the bicycle inside the room on the equator of
the large ball called earth. The speed or direction of the rotation of the large ball (aka earth) doesn't change the speed
of light. The speed of light is additive to the speed of the flashlight that is moving with the surface the earth. If the
bicycle were really stationary in space, it would fly off the surface of the earth at a speed of over 1 million miles per
Now suppose the room where the bicycle is fixed is on a train that is moving 1,000 MPH at the equator. Now suppose
there is another duplicate setup on another train moving the opposite direction. In both cases, the speed of light is
additive to the speed of the flashlight on the bicycle relative to the room and it doesn't change regardless of the speed
or direction of movement of the bicycle fixed inside a room on a moving train on a moving ball called earth. This is
analogous to the movement of the surface of the earth relative to the center of the earth and the movement of the
earth relative to the sun. In both cases, there is no Doppler shift from the fixed light inside the trains but as viewed
from the earth, there is Doppler shift of the same light that is emitted from the moving train.
Now suppose the bicycles are taken off the trains and riders propel the bicycles in opposite directions on the equator of
the ball called earth that is rotating at a speed of 1,000 MPH relative to the center of the earth. The flashlights are
now moving emitters in the earth frame. The speed of light from the flashlights is c relative to the speed of the earth.
It isn't additive to the speed of the bicycle on the earth. It is only additive to the speed of the frame where the
All this simply shows that the speed of light is relative to the frame of reference. It is additive to a remote frame of
reference. The speed of light rides along with the moving frame of reference. The speed of light doesn't throttle the
speed of a moving object.
We know the earth is an object moving through space at some very high speed. A space craft could be moving at any
speed relative to our earth or sun and the speed of light inside that craft would be a constant "c" relative to the
moving craft. The craft could be moving 2c or any multiple of c and the speed of light inside the craft would be c.
Force field interaction.
To explain the concept of how light and other things interact in a force field, I begin with a somewhat appropriate
analogy. Consider the force at the center of a muddy river. A suspended tiny particle flows along almost
unencumbered while a log on the surface flows along with more encumbrances. The analogy isn’t exact but
substitutions should convey the concept. On a very long river with very uniform flow, a log will proceed at almost the
same velocity of the water. Water and a tiny particle will flow past the log.
- The flow/force of the river would seemingly not exist compared to the log.
- A casual observer would not perceive motion of the water or the tiny particle.
- A skilled observer with precise tools could observer the flow.
The river compares to the earth force field. The tiny particle compares to light. The log compares to the earth. Light in
the earth or sun force field travels c compared to those force fields. Light also travels c compared to space. Just as
light is Doppler shifted and also changes speed as it leaves the moving car, it also changes as it moves from the space
force field to the sun force field. The light is refracted as it moves from space through the sun force field or gravitational
lens. The Eddington eclipse photos show that light going through a lens is refracted. The sun’s gravitational lens is a
lens. The examination of the light being refracted as it goes through any lens can show the rim of the lens.
If the forces that move the earth were removed, the earth would stop moving and spinning. That is because space is
not empty. It is very thin. It causes Interstellar reddening and drag on spacecraft like Pioneer 10 that is slowing. We
basically say that light travels c in an observer’s frame of reference vacuum. Consider instead that light travels c as
compared to an observers force field vacuum.
With that we have:
- A force field propels the earth.
- The earth resists the force field so it somewhat lags the force field.
- A force field that light travels c within omnidirectional unencumbered.
The earth resists the force field so the earth movement is slightly behind the force field. Light speed is not actually
relative to earth. It is relative to the earth force field. That is; light is relative to the frame or force field just as it is
relative to different mediums.
This applies with relative speed of light. That is, light is relative to the frame or force field just as it is relative to
Why do some people think 10 plus 10 equals 10?
Some people think a person walking 10 feet in 10 seconds on a moving platform that is also moving 10 feet in the
same 10 seconds has only moved 10 feet in 10 seconds instead of 20 feet in 10 seconds.
Let me make the picture perfectly clear.
The person walks at a rate of 10 feet in 10 seconds.
The person is walking on a platform that moves at the same rate of 10 feet in 10 seconds. .
10 feet in 10 seconds plus 10 feet in the same 10 seconds equals 20 feet in 10 seconds.
Some people think the person has only moved 10 feet because the person does not know the platform is moving.
Those people think the ground is supposed to be considered to be moving instead of the platform.
It is easy to understand why those people think the ground is considered to be moving instead of the platform. Those
people have been trained that the theory of relativity makes it clear that the ground is moving because the person on
the platform thinks the platform is not moving.
The speed of light is not constant but it's speed is also relative to the frame of reference. THE THEORY OF RELATIVITY IS
Well in my scenario the person who is walking on the moving platform knows the platform is moving because she made
the platform to be a moving platform. She also has tape measures and lasers and Global Positioning System devices
and cell phone locators on the ground, and on the platform, and she is holding the devices while she is walking on the
platform she made to be a moving platform. There can be no doubt in the mind of the woman while she is walking on
the moving platform that the platform is moving while she is walking. There is no doubt in her mind that she has
moved 20 feet in 10 seconds relative to the ground while she has moved only 10 feet on 10 seconds relative to the
Some people read this and missed the fact that the person who built the platform is a woman.
That shows that there is a difference between just reading and carefully reading and
Copyright 2008, 2009 edited 04 Oct 2011
All rights reserved.
Speed of light
from a flashlight
on a bicycle or
on a train or on
any moving platform
Refraction is the change in direction of a wave due to a change in it's speed when the wave passes
from one medium to another at any angle other than 90° or 0°.
- When in outer space, light travels “c” as compared to the outer space medium.
- When in a planet or sun gravitational field, light travels “c” as compared to a planet or sun medium.
When light leaves outer space and enters a planet or sun gravitational field, it changes direction due to
changing speed as it moved from the outer space medium to the sun or planet medium. It changes
again as it leaves the sun or planet medium and enters the space medium.
A gravitational lens is a type of lens that refracts light as it changes speed when it moves from being
“c” compared to outer space to be moving “c” compared to inner space. The lens edge or boundary
between outer space to inner space is the same lenses boundary that applies to any theory of
gravitational lens and orbital object that is either pulled back into or escapes the gravity field.
That is as specified in Classical hierarchy Relativity.
All the eclipse photos and calculations show the refraction of light due to the change in direction of light
as it changes speed as a result of passing from the outer space medium and goes through the sun’s
gravitational medium. Space and time do not bend. Light is just refracted.
There it is. Proof of ChR using Eddington and other eclipse photos and calculations.
Copyright. Don E. Sprague 2007 edited 13 oct 2011