A Train, Three Clocks, and an Observer

And yet experiments indicate that it is. Clearly, there is a problem with the theory you are using to prove it is impossible - when theory and reality conflict, reality must win. The theory must be modified. And that's what Einstein ad his contemporaries did.

Einstein's theoretical resolution is that there is no such thing as absolute velocity - ie no observer has absolute velocity - and that theoretical nature of time and space is such that time and length measurements made by observers in relative motion will differ.

Lorentz proposed a similar resolution. He also suggested that the nature of time is such that the time measurements depend on location and absolute motion in such a way that any velocity appears to be zero absolute velocity. In this context, Lorentz would suggest that moving the from the middle to the ends changes their time so that they will still appear sunchronized.

The two explanations (Einstein and Lorentz) are equivalent paradigms - they give exactly the same experimental results. The first is generally preferred, because the second proposes an unmeasurable entity (an absolute velocity standard).

 

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That's not the issue. The issue is, the lights travel an equal time to impact each other, so they travel the same distance by definition. If the observer moves during that time, he is no longer at that place of impact. He is impacted earlier by one and later by the other, so again, light travel times are different to impact him, which means the distances are different, as he had a velocity. It is a fact that can't be disputed.

 

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Stop and think, for a moment: What's so special about light? What would happen if your light sources were replaced by, say, identical paintball guns? Are you denying Galilean relativity as well?

Clearly, since we're all hassling you, it can be disputed. Also, it's known to be false, by experiments that explicitly test your claims. Nature says you're wrong.

 

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Nothing is special about light, except that it's the fastest we can measure.

If two paint balls were launched simultaneously towards each other at the same speed, they will each travel the same distance to impact each other. If you placed them 10 feet apart and fired them at each other, the balls will impact each other at the midpoint, 5 feet away from each other. If there was an observer at that 5 foot mark when the balls were fired, and he moved during that time of flight, one ball would travel say 4 feet to hit him and one would travel 6 feet to hit him. One ball would hit him first, and a time interval later the second would hit him. He was 1 foot from the midpoint. Figure the time difference and you can figure his velocity. This is all done in the volume of space, of course.

 

Did you miss post 41, MD?

I think funkstar was thinking of paintball launchers on the train, one at each end. When fired simultaneously, they'll always meet in the middle regardless of the train's motion.

But, this is not quite how light works either, although it is similar in that the velocity of light is always the same relative to the train.

 

It's the speed that is special. It's the fastest local speed there is. It's built in to the fabric of the universe. It's the speed that is equivalent to infinite rapidity (rapidity is the distance travelled by a moving clock divided by the time elapsed on that clock. Or the proper length of a moving rod divided by the time it takes that rod to pass a given location.)

 

Pretty much. MotorDaddy, would you agree?

(That was the point: I was trying to figure out the extent of the madness.)

 

If paint balls always traveled at 50 m/s, and the train was 100 meters long, and each was fired from opposing ends towards each other simultaneously, the balls would impact each other in exactly one second. If there was a midpoint observer and the train had a zero velocity, the balls would impact the observer simultaneously. If the train had a velocity, the observer would travel with the train, which doesn't affect the balls flight, hence the observer would be hit by one ball in less time than the other, as one would have to travel further than the other to impact him, as he was no longer at the original midpoint. Note, if the balls continued flight without hitting the midpoint observer, the balls would impact each other at the original midpoint in space, but the observer would no longer be there to be hit simultaneously.

 

Looks like I'm being ignored?

 

Just so we're clear: The paint ball guns are on the train, in this scenario.*

*This turns out not to matter for light sources, but I'm trying to establish whether you disagree with Galilean relativity as well.

 

Me too, he completely ignored my post, not even acknowledging I'd made it and he replied to the posts around it.

What's the matter MD? You demanded responses and now you've got them have you realised you're in over your head? At least be honest and admit it rather than hoping if you blank any reply you can't understand they'll go away. Jack tried that method and look at what a failure his claims are.

 

What "given location?" Do you mean to say an absolute location in space, as if that location had an absolute zero velocity in space?

 

A given location in a given reference frame. Like New York, New York. Or Japetus. Or the middle of the train. Or Barnard's Star.

 

I'm not Jack and that seems to be all you want to talk about. You never responded to the 5 statements, and whether you agree or disagree with them. Stick to my scenario and tell me where I am wrong. Tell me where my mistake is. Just saying "that's the way nature is" is a cop out, and sounds like a religious person saying, "it's faith." Tell me exactly where my mistake is in my example. Heck, tell me why paint balls that are 100 meters apart and fired towards each other simultaneously, that always travel at 50 m/s, don't impact each other in exactly one second.

 

Do you acknowledge that objects can have a velocity in this universe?

 

Only relative to something else. What do you think about what I said in post 41?

 

Velocity has nothing to do with another object. Velocity is directional. Each object in this universe has a velocity of its own. Space is an infinite volume. There are objects of mass in motion in that volume. Volume has measurements. The velocity of an object in motion in that volume is relative to the measurements of the volume. The velocity of an object has nothing to do with another object's motion.

I'll give a short example:

Say a bus is 100 feet long. There is a man with a ball at midpoint of the bus. The bus leaves the bus station and is traveling away from the bus station at the rate of 25 feet per second. If the man on the bus throws the ball towards the back of the bus in such a manner that the ball hits the back door of the bus 50 feet away from his location on the bus, and the time of travel of the ball is exactly one second, what is the ball's velocity? 50 ft/sec? No. Because during the time of flight, the back of the bus moved towards the ball in flight, so the ball only really traveled 25 feet in that one second duration. That can be verified by measuring the distance between the ball and the bus stop, as the ball is traveling towards the bus stop at a rate of 25 ft/sec, even though on the bus the man insists the ball traveled 50 ft/sec. He fails to acknowledge the bus's velocity, which is a major mistake.

 

So let's get this straight. So let's say that I'm sitting in the back seat of a car at a stop and toss a ball to a passenger in the front seat at say 5 mph.

Now say the car is driving at 70 mph. I make the same toss. Your saying that since the ball is only traveling forward at 5 mph and the car is moving forward at 70 mph, the ball will land behind me in the car?

 

Says you.

Yes, relative to the bus.

This is all correct... relative to the ground.

You're assuming that the ground isn't moving, which is fine... but it's also fine to assume that the ground is moving. For example, if you assume the bus to be at rest, then you also assume the ground is moving at 25 ft/sec backwards.

Do you think that the ground is absolutely at rest, like the folks that got all grumpy at Galileo?

 

The ball is already traveling with the car, so the ball has the same velocity as the car. If you accelerate the car you accelerate the ball, as the additional force can be verified, ie torque. Ever put extra passengers in your car and notice how the the car accelerates at a slower rate with the additional weight?

If the ball is stationary relative to the car, the ball has the same velocity as the car. If the car is doing 70 MPH, so is the ball.