light is time

[Acitnoids]

Motor Daddy,
What if I made my measurements from the rear bumper of each vehicle? Now it's way past my bedtime but I wanted to tell you ... If both cars had the same mass and they were traveling at exactly the same velocity then, in a head-on collision, both cars would come to a complete standstill (as if hitting a brick wall at half its velocity) and the amount of force transferred between each automobile depends on their mass and velocity.

 

[arfa brane]

Light travel time defines distance, try again!

You aren't seeing it are you? We define distance, and so the distance that light travels.
It doesn't "define" it, we do.

 

[Motor Daddy]

Motor Daddy,
What if I made my measurements from the rear bumper of each vehicle. Now it's way past my bedtime but I wanted to tell you ... If both cars had the same mass and they were traveling at exactly the same velocity then, in a head-on collision, both cars would come to a complete standstill (as if hitting a brick wall at half its velocity) and the amount of force transferred between each automobile depends on its mass and velocity.

If you made the measurements from the rear bumper, the rear bumpers would have to touch for the cars to have traveled 120 km. But, when the front bumpers impact each other, each car's velocity dramatically decreases to 0 m/s. If the rear bumpers don't touch, the clock keeps ticking. So the distance is not 120 km for each car, and has stopped changing, and yet the clocks are still ticking. How do you know what the velocity was when the time continues to tick and the distance traveled was less than 120 km???

 

[Motor Daddy]

You aren't seeing it are you? We define distance, and so the distance that light travels.
It doesn't "define" it, we do.

Wrong, light travel time defines the meter, look it up!

 

[arfa brane]

Wrong, light travel time defines the meter, look it up!

What's a "meter"?

 

[Motor Daddy]

What's a "meter"?

http://en.wikipedia.org/wiki/Meter

The metre (or meter), symbol m, is the base unit of length in the International System of Units (SI). Originally intended to be one ten-millionth of the distance from the Earth's equator to the North Pole, its definition has been periodically refined to reflect growing knowledge of metrology. Since 1983, it is defined as the distance travelled by light in vacuum in 1⁄299,792,458 of a second.

 

[arfa brane]

Originally intended to be one ten-millionth of the distance from the Earth's equator to the North Pole

Why wasn't the metre defined in terms of the distance traveled by light, originally?
Who defined it? Were they a member of the human race, and if so, does that mean the metre is an invention that existed before humans knew about the finite speed of light?

Are you still convinced that light, not humans, is what defines the metre?
Another question: do humans decide what light is, or does light define itself somehow?

 

[Motor Daddy]

Why wasn't the metre defined in terms of the distance traveled by light, originally?
Who defined it? Were they a member of the human race, and if so, does that mean the metre is an invention that existed before humans knew about the finite speed of light?

Are you still convinced that light, not humans, is what defines the metre?
Another question: do humans decide what light is, or does light define itself somehow?

I'll ask again, since you now know the definition of a meter.

If a light was emitted at 12:00:00, how far did it travel in one second?

 

[arfa brane]

If a light was emitted at 12:00:00, how far did it travel in one second?

How about: it traveled the distance that light travels in one second?

I already knew the definition of the metre. You appeared to believe that a metre is something that has nothing to do with humans making decisions about what distance and time are. You're just being smug and ignorant.

 

[Motor Daddy]

How about: it traveled the distance that light travels in one second?

I already knew the definition of the metre. You appeared to believe that a metre is something that has nothing to do with humans making decisions about what distance and time are. You're just being smug and ignorant.

So are you saying it traveled ~186,000 miles in the duration of one second?

The meter is a unit of measure, like a lb, or HP, or teaspoon, or gallon, etc..

We use them to communicate and measure.

What are you confused about? Do you think I believe light has a mind of its own, and that it was credited with the invention of the meter by all the other light in the universe?

 

[arfa brane]

Remember this?

You aren't seeing it are you? We define distance, and so the distance that light travels.
It doesn't "define" it, we do.

First you say this:

Wrong, light travel time defines the meter, look it up!

Then you say this:

The meter is a unit of measure, like a lb, or HP, or teaspoon, or gallon, etc..

We use them to communicate and measure.

So is it wrong or right? Do we decide what a metre is, or what a second is, as I stated?

 

[Motor Daddy]

Remember this?

First you say this:
Then you say this:
So is it wrong or right? Do we decide what a metre is, or what a second is, as I stated?

Light travels a distance in 1⁄299,792,458 of a second. That distance is a meter. Yes, we are human, and we use light to define the meter. Answer the question, did the light travel ~186,000 miles in that second?

 

[arfa brane]

Yes, we are human, and we use light to define the meter.

So when you said I was wrong about humans defining the metre, were you just being smug, or were you being ignorant, or a bit of both?

Answer the question.

 

[Acitnoids]

Motor Daddy, I have almost unlimited patients in all things except two. The first, drama queens and the second, ignorance. You fall under the latter. Philosophy and physics are no longer considered the same discipline and everthing you have said thus far has nothing to do with physics. You said:

Originally Posted by Motor Daddy Velocity doesn't depend on another objects velocity.

You are dead wrong, PERIOD. I'm not sure what you think you're accomplishing with this declaration. I'm under the impression that you are in denial of the fact that there are more than a few basic concepts you have yet to understand (such as relative velocity which is the basis for sound measurements and predictions as well as the cause of this thread). Instead of admitting this you chose to ramble off a bunch of gibberish that is in total disregard to the fact that physics is the science of measurements. The amount of force exchanged between any two vehicles involved in a head-on collision is one such measurement. Contrary to your claim this depends (in part) on the sum of each cars velocity. The part you are willingfully ignorant of is the fact that every observer can (I didn't say must) declare any other object to be at rest. I'll ask one last time. If I'm traveling down the freeway at a constant velocity of 120 km/hr, relative to the surface of the Earth, and I pass another car moving in the same direction as I am, but traveling at a constant velocity of 115 km/hr relative to the surface of the Earth. What is the other cars canstant velocity relative to me? This measurement (which will aid in revealing the amount of force exchanged between both of our vehicles in the event I should rear-end them) is dependent on comparing one cars velocity to the other. I don't care what you think. You have to explain this through physics not philosophy. If you are not willing to admit your mistakes then please, for the love of all that's true in this world, stop posting in the science sub-forums.

 

[Motor Daddy]

You have a gross misunderstanding of velocity, particularly with the direction of travel.

Two cars traveling down a road in the same direction of travel. One is 115 km from the start line, the other is 120 km from the start line. They both started at the start line and left at the same exact time.

Now, you are in the car that is 120 km away from the start line an hour after the start of travel. You want to say you have a right to say the other car is traveling away from you at 5 km/hr in the opposite direction?? Go ahead, we both know you are dead wrong! You have a serious misunderstanding of velocity and direction of travel. Furthermore, nothing is traveling 5 km/hr!

Skirt the issue all you want, if light travels for one second in a vacuum, it traveled ~186,000 miles, regardless of how far away the source is after the one second duration! If the source traveled the opposite direction of travel during that one second at .5c, the distance between the source and the light will be greater than 186,000 mi. The source has nothing to do with the velocity of light after the emission of said light! Get it through your head!

 

[Acitnoids]

Originally Posted by Motor Daddy
Two cars traveling down the road in the same direction of travel. One is 115 km from the start line, the other is 120 km from the start line. They both started at the start line and left at the same exact time.

My god, you are so f**king ignorant. Who said anything about a start line. Acceleration is not the same thing as constant velocity.

Originally Posted by Acitnoids
If I'm traveling down the freeway at a constant velocity of 120 km/hr, relative to the surface of the Earth, and pass another car moving in the same direction as I am, but (it is) traveling at a constant velocity of 115 km/hr relative to the surface of the Earth. What is the other cars constant velocity relative to me?

Go ahead! Add whatever words that pop into your head so that you can feed your own narcissism. If you can't answer such a basic scenario then you have no right discussing higher applications.

 

[Motor Daddy]

My god, you are so f**king ignorant. Who said anything about a start line. Acceleration is not the same thing as constant velocity.

Acceleration is the rate of change of velocity. If a car travels 120 km in exactly one hour, the velocity is 120 km/hr. You have some serious learnins to do!

Go ahead! Add whatever words that pop into your head so that you can feed your own narcissism. If you can't answer such a basic scenario then you have no right discussing higher applications.

I just answered the scenario. The distance and time were measured. How did you measure the 5 km/hr, and what object traveled 5 km/hr, and in what direction did it travel, towards the start line?? That is the question!

 

[Acitnoids]

Originally Posted by Motor Daddy
I just answered the scenario. The distance and time were measured. How did you measure the 5 km/hr, and what object traveled 5 km/hr, and in what direction did it travel, towards the start line?? That is the question.

Once again with the start line. You do know that an object can not travel 120 kilometers in one hour unless it is already traveling 120 km/hr at the moment it crosses the 'start line'? It seems that "You have some serious learnins to do!"

 

[Motor Daddy]

Once again with the start line. You do know that an object can not travel 120 kilometers in one hour unless it is already traveling 120 km/hr at the moment it crosses the 'start line'? It seems that "You have some serious learnins to do!"

I was giving a simple example of a constant velocity, whereas the cars cross the start line at a constant velocity and continue without acceleration the entire hour. Why are you bringing acceleration into the picture? It has nothing to do with what you are talking about. You are trying to say the 115 km/hr car is traveling in the direction away from you in your 120 km/hr car, towards the start line at 5 km/hr. Prove it!

 

[Motor Daddy]

You realize the start line was where the cars were when the timer was started, correct? As the cars crossed the line the timer was started. An hour later one car is 120 km from the start line and one car is 115 km from the start line. So in order for the 115 car to be traveling away from the 120 car (like you are suggesting), it has to be traveling in the direction towards the start line, correct?