The Relativity of Simultaneity

[origin]

You say there is a spaceship moving along at 25 kph. How did you determine the ship is traveling at 25 kph? Did you measure the distance it traveled in a specific amount of time? How exactly did you measure the distance, and what are the points you measured from? Certainly you did not measure from the other ship, , as the distance was closing at the rate of 50 kph. So exactly how did you determine the ship was moving at 25 kph? You don't even understand where you go wrong. You just make up numbers, and then change the numbers in order to fit Einstein's delusional world. Do you understand that in order for you to have measured the velocity of an object that the time must have already elapsed, and that you are looking at a record of the past? The stop watch has already stopped, the test is completed. Why can't you comprehend that??

...and you told me to assume the ship is moving along at 25 kph. Then you want me to assume that the ship can be considered at rest (with respect to what I don't know). Are you now telling me to disregard the first assumption that the ship is moving along at 25 kph, and to assume the ship has a zero velocity? Make up my mind, will you? Which is it?

By the way, even a zero velocity has to have been measured. How did you measure the zero velocity, and how much time did you perform the test, or has the ship always been at a zero velocity? Did it appear out of nowhere instantaneously, or did it come from some other place a distance away? If so, should I disregard that motion in my calculations of distance and time? You're clueless!

Why are you are making such a supreme effort to not understand? I don't know why you want to live in willful ignorance - how odd.:shrug:

 

[Motor Daddy]

Why are you are making such a supreme effort to not understand? I don't know why you want to live in willful ignorance - how odd.:shrug:

Why do you tell me to assume the ship has a 25 kph velocity, and then change your story and tell me the ship has a 0 kph velocity?? :shrug:

How did you determine the 25 kph velocity??

 

[Magneto_1]

What do you mean when you say "at rest?" Describe your concept of "at rest."

Motor Daddy, Let me take a swing at this, if I may?


The concept of the "inertial frame of reference" and "rest" are a bit confusing to the "Relativist."

This is why I was forced to to add an addendum to Newton's First Law of Motion in the form of an Aphorism: Super Principle of Motion #1.

I will make the following quote from the book: Super Principia Mathematica - The Rage to Master Conceptual & Mathematical Physics: The First Law of Motion; by Robert Louis Kemp


All uniform motion and velocities are determined to be relative, and are the measure of the time rate of change in the position of a body, relative to some frame of reference.

The specific external uniform translational velocity of a system mass body in motion is the displacement of the Center of Mass of that body, over equal distances, in a particular direction over equal amounts of time, relative to an external inertial frame of reference and the center of mass of the system body.

There is no way to measure the absolute translational velocity of a system body in motion in the universe. The velocity of a body can only be measured relative to its own-ship Center of Mass/Momentum frame or to other external frames of reference in the universe.

The velocity of a body is therefore a relative effect, and is typically measured relative to the earth. However, the earth itself is not at rest, it is rotating on its axis, and revolving around the sun. The sun itself is moving relative to the center of our Milky Way galaxy; and our galaxy is moving relative to other galaxies. All velocities must be measured relative to some other specified coordinate system.

Law 1.1:

First Law of Motion — Relative to an Inertial frame of reference, a body preserves a state of uniform momentum, kinetic energy, squared velocity, and velocity, in a straight line equal distances in equal times, unless it is compelled to change its state of uniform motion by an unbalanced external or internal force acting on the body.​

Aphorism 1.1:

Super Principle of Motion #1 - There is always motion of one body relative to any other body at rest in the universe; and the relative motion of any one body can never be reduced to zero. Therefore there is no frame of reference that can be measured that is truly at rest; thus, being at rest is just as natural as being in a state of uniform motion; rest is therefore a special state of motion.​

Best

 

[AlphaNumeric]

I will make the following quote from the book: Super Principia Mathematica - The Rage to Master Conceptual & Mathematical Physics: The First Law of Motion; by Robert Louis Kemp

Referring to yourself in the third person, to a book you wrote, as a means of trying to legitimise your claims is dishonest, both in terms of providing 'scientific' references (which your work is not even close to) and in terms of trying to hide self promotion.

If you can't provide reputable sources don't pretend you have any. Don't pretend you aren't Robert Kemp when you've repeatedly said you are him. Don't promote a book you authored which is vanity published and hasn't passed (and couldn't) scientific review. There are anti-promotion rules on this forum and referring to yourself in the third person doesn't mean you can ignore them.

 

[Motor Daddy]

Motor Daddy, Let me take a swing at this, if I may?

There is no way to measure the absolute translational velocity of a system body in motion in the universe. The velocity of a body can only be measured relative to its own-ship Center of Mass/Momentum frame or to other external frames of reference in the universe.

Strike 1!

Yes there is, and I've already shown how multiple times on this board. I did it in this thread too.

Since the meter is basically defined as a specific light travel time, distance is simply light travel time. Light travels in space at a specific speed. So it is possible to measure the velocity of a box in space from inside the box, or a train's velocity in space from inside the train, by measuring the amount of time it takes light to travel. Since light always travels at the same speed, it is possible to know one's own motion from "inside the box" by simply measuring the amount of time it takes light to travel a specific distance in the box.

I've done this in this thread as to showing the absolute velocity of the embankment, and also the absolute velocity of the train. Neither velocity are derived from the other.

 

[wellwisher]

Wrong. Relativistic mass is relative, since it depends on RELATIVE VELOCITIES.

Let me give an example. In a particle accelerator, some particles are given velocity close to C, while most of the matter in the lab will remain stationary. This velocity can't as easily be defined as relative,since there will be energy differences we can measure, if you look closer. We can tell the difference between the relative references by the magnetic field strengths, since this will increase with absolute velocity, but it it won't increase with relative velocity.

The lab will not start to generate magnetic fields simply by assuming all is relative and the lab is in motion when it is not. That would be a magic trick, since charge will need actual motion. Only where there is real energy and absolute velocity, will there be real effects. The rest is pretend that needs magic to fool the audience.

I see relativistic mass as the mass version of the magnetic induction caused by charge velocity. It creates fields which store energy. We can't magically make a strong magnetic field appear in our reference by assuming relative motion. It needs absolute motion.

 

[Pete]

Nope.

Meter rulers on the train are not contracted, and clocks on the train are not dilated.

1. The meter rulers on the train are 1 meter in length, there is no contraction of rulers. A meter ruler is exactly 1 meter in length. If a stick is 0.99999999986325 meters long, it is not a meter stick, it is a 0.99999999986325 stick!

2. Clocks on the train are not dilated. A second is exactly one second, by definition.

I'm giving you the numbers in the mathematical world of time dilation and length contraction, Motor Daddy, just as we agreed.
A bunch of standard metre rulers and standard clocks are on the train, but because the train is moving they are no longer accurate.
The metre rulers are short.
The clocks tick slowly.

Would it help if I say "train ruler" instead of "metre ruler"?
A train ruler is 9.9999999986325 metres long.

Both a meter and a second are standard definitions of distance and time, they don't change. You are baiting and switching by first saying the train is 10 meters long, and then saying it's actually 9.9999999986325 meters long. Which is it, is it 10 meters long or is it 9.9999999986325 meters long??

The train is 10 metres long.

Also, one very important point: The front and back of the train are not passing the A and B points on the embankment, they are perfectly aligned with the embankment points, simultaneously. In order for the A and B points on the embankment to be 10 meters apart, and the train's front and back perfectly aligned simultaneously with the embankment's points, the train must be exactly 10 meters in length from front to back.

Yes, that's what I said in the conclusion to that post.

If you say the train is actually 9.9999999986325 meters long

I don't.

The train is 10 actual metres long.
Rulers on the train are contracted to 0.99999999986325 m.
There are 10.000000001367545 train rulers in 10 actual metres.
The train observer measures the train to be 10.000000001367545 rulers long.

 

[Magneto_1]

So it is possible to measure the velocity of a box in space from inside the box, or a train's velocity in space from inside the train, by measuring the amount of time it takes light to travel. Since light always travels at the same speed, it is possible to know one's own motion from "inside the box" by simply measuring the amount of time it takes light to travel a specific distance in the box.

Motor Daddy,

Free from any gravitational field and the box moving at relativistic speed will conclude that what you have written above about the "Box Inertial Frame" and "light" are true.

However, an external observer outside of the box and making measurements of the "light pulse" and the very high speed moving "Box Inertial Frame", will conclude that: time, distance, wavelength, and frequency are all different for the "Proper" Center of Mass, moving "Box Inertial Frame."

Best

 

[Motor Daddy]

I'm giving you the numbers in the mathematical world of time dilation and length contraction, Motor Daddy, just as we agreed.
A bunch of standard metre rulers and standard clocks are on the train, but because the train is moving they are no longer accurate.

You mean you are on the train and acknowledge the "train is moving?" What is it moving compared to, and at what rate, and how did you measure that rate on the train?

 

[Motor Daddy]

The train is 10 actual metres long.
Rulers on the train are contracted to 0.99999999986325 m.
There are 10.000000001367545 train rulers in 10 actual metres.
The train observer measures the train to be 10.000000001367545 rulers long.

So the meter sticks on the train are not actually one meter in length? In other words, how much time does it take for light to travel the length of one of those train sticks (which are not a true meter) when it is on the train parallel to the tracks?

 

[Pete]

You mean you are on the train and acknowledge the "train is moving?" What is it moving compared to, and at what rate, and how did you measure that rate on the train?

No, I'm not on the train.
Yes, I'm working with the assumption that the embankment is at absolute rest, and that the train is moving at 4958 m/s.
The train observer does not yet know if the train is moving.

 

[Motor Daddy]

No, I'm not on the train.
Yes, I'm working with the assumption that the embankment is at absolute rest, and that the train is moving at 4958 m/s.
The train observer does not yet know if the train is moving.

How much time would it take light to travel the length of one of those train sticks when it is on the train?

 

[Pete]

From front to back, it takes t=d/(c+v) = 3.335585787248 ns
From back to front, it takes t=d/(c-v) = 3.335696117627 ns

 

[origin]

Why do you tell me to assume the ship has a 25 kph velocity, and then change your story and tell me the ship has a 0 kph velocity?? :shrug:

Golly, if that has blown your mind then this is really even more fruitless than I first thought. If willful ignorance is bliss - you certainly have reached nirvana.

 

[Motor Daddy]

From front to back, it takes t=d/(c+v) = 3.335585787248 ns
From back to front, it takes t=d/(c-v) = 3.335696117627 ns

So the light travel time one way is different than the light travel time the other way, when measured on the train?

 

[Motor Daddy]

Golly, if that has blown your mind then this is really even more fruitless than I first thought. If willful ignorance is bliss - you certainly have reached nirvana.

Thanks for the reply, it speaks volumes of your inability to prove me wrong, and your inability to explain yourself.

 

[Motor Daddy]

Ladies and Gentlemen, Pete has left the building.

 

[Emil]

@Motor Daddy,
What I will say is for general and not necessarily for the present example.
I agree with reporting speed at speed light.
But be prudent because this speed is not completely determined because the orientation is undetermined.
So if the object1 has a speed V1 and the object2 has a speed V2,
that does not mean relative speed between these two objects is V = V1-V2.
This addition or subtraction is made vectorial, taking into account the orientation of the two velocity vectors.

They make the same mistake, because if the observer is not on the train and not on the tracks, the relative speed between him and the train is made through a vector decomposition.
So when the train runs right in front of the observer, the relative speed between them is 0.

 

[Pete]

Ladies and Gentlemen, Pete has left the building.

I have a life, MD. I'm assuming you do too?
I made the previous couple of posts over breakfast. Posting over the next 8 hours will be sporadic between classes.

So the light travel time one way is different than the light travel time the other way, when measured on the train?

Those are the actual travel times.
Measuring on the train is trickier, because the train clocks are dilated, and haven't been synchronized yet. That's the next step, if you're happy with the facts so far.

 

[Motor Daddy]

Those are the actual travel times.
Measuring on the train is trickier, because the train clocks are dilated, and haven't been synchronized yet. That's the next step, if you're happy with the facts so far.

What do you mean by "the actual travel times?"

Do you plan to use a different sync method from the one you (indirectly) agreed to using for the embankment?

The clocks on the embankment are absolutely sync'd. In other words, at any point in time they read as one. Another way to put it is that when I am at one clock and it says 12:00:00, I know for a fact the other clock reads 12:00:00, like I know the time in NY is the same time in Florida at any point in time. One time zone.