light is time

Originally Posted by Motor Daddy
We need one universal time zone and this nonsense will go away.
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This can only happen if every observer in the hole entire universe could agree on a single reference frame from which they can all calculate their relative velocities (such as our Sun). However, this is not possible. Some observers will be to far away to be able to observe that single reference point because of our individual Hubble Volumes. The only "universal reference point" that I know of is the moment of the Big Bang (BB). If you were to observe the temperature of the microwave background radiation as X and yet I observed it as Y then we could deduce our relative velocities from each other according to the BB. Everything is moving away from the BB at a constant rate eventhough this rate can be different between each observer immersed inside our space-time continuum. Logically speaking, the closer any object is to the BB the younger the universe will appear to them. From what I've worked out, the faster any object is traveling relative to another object the longer it takes to move away from the BB according to the other observer. The same thing applies to strong gravitational fields. The stronger the gravitational field you find yourself in the longer it takes to move away from the BB according to any observer immersed inside a weaker gravitational field.
 
Acitnoids said:
This can only happen if every observer in the hole entire universe could agree on a single reference frame from which they can all calculate their relative velocities (such as our Sun). However, this is not possible. Some observers will be to far away to be able to observe that single reference point because of our individual Hubble Volumes. The only "universal reference point" that I know of is the moment of the Big Bang (BB). If you were to observe the temperature of the microwave background radiation as X and yet I observed it as Y then we could deduce our relative velocities from each other according to the BB. Everything is moving away from the BB at a constant rate eventhough this rate can be different between each observer immersed inside our space-time continuum. Logically speaking, the closer any object is to the BB the younger the universe will appear to them. From what I've worked out, the faster any object is traveling relative to another object the longer it takes to move away from the BB according to the other observer. The same thing applies to strong gravitational fields. The stronger the gravitational field you find yourself in the longer it takes to move away from the BB according to any observer immersed inside a weaker gravitational field.
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Velocity doesn't depend on another object's velocity. Velocity is a measure of distance and time, which already occurred in the past and was measured...or are you suggesting that the future can be measured??
 
Originally Posted by Motor Daddy
Velocity doesn't depend on another object's velocity. Velocity is a measurement of distance and time, which already occured in the past and was measured ... or are you suggesting that the future can be measured??
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All I was commenting on is the difficulty in ascribing a "universal time zone" (as you put it). In one hand everything in the hole universe would have to relate their motion to an established object such as our sun. This is impossible due to observational boundaries. In the other hand eveything in the hole universe would have to establish their distance (time) from a universal event (such as the BB) and then communicate that information to other locations so that those other locations can deduce each others relative velocities from said event (pretty much impossible). As for your comment ... I disagree. Relative velocity depends on another object's relative velocity. Let's say that I am cruising down the freeway at a constant velocity of 120 km/hr. This velocity is in relation to the surface of the Earth. If I were to pass another automobile that was traveling along with me at a constant velocity of 115 km/hr, relative to the surface of the Earth, then I would have a relative velocity of 5 km/hr relative to both of our automobiles. Now let's say that there was another automobile traveling towards me at the same constant velocity I was traveling toward them (relative to the surface of the Earth). I would be correct if I said that that automobile had a velocity of 240 km/hr relative to me even though the car I just passed (traveling with me) would say that it was traveling 235 km/hr relative to them. I'm not going to get into a debate over semantics with you but I'm curious. How would you describe these scenarios without using another object's velocity?
 
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Acitnoids said:
All I was commenting on is the difficulty in ascribing a "universal time zone" (as you put it). In one hand everything in the hole universe would have to relate their motion to an established object such as our sun. This is impossible due to observational boundaries. In the other hand eveything in the hole universe would have to establish their distance (time) from a universal event (such as the BB) and then communicate that information to other locations so that those other locations can deduce each others relative velocities from said event (pretty much impossible). As for your comment ... I disagree. Relative velocity depends on another object's relative velocity. Let's say that I am cruising down the freeway at a constant velocity of 120 km/hr. This velocity is in relation to the surface of the Earth. If I were to pass another automobile that was traveling along with me at a constant velocity of 115 km/hr, relative to the surface of the Earth, then I would have a relative velocity of 5 km/hr relative to both of our automobiles. Now let's say that there was another automobile traveling towards me at the same constant velocity I was traveling toward them (relative to the surface of the Earth). I would be correct if I said that that automobile had a velocity of 240 km/hr relative to me even though the car I just passed (traveling with me) would say that it was traveling 235 km/hr relative to them. I'm not going to get into a debate over semantics with you but I'm curious. How would you describe these scenarios without using another object's velocity?
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Let's take your 240 km/hr scenario into consideration.

There is a straight road that is 240 kilometers long. Two cars (one car from each end) are traveling at the same velocity towards the midpoint of the road that is 120 kilometers from each end of the road. The cars had stop watches activated when they started their journey towards the midpoint. They impact each other exactly at the midpoint and the stop watches stop at precisely the same elapsed times. Each car traveled the same distance in the same elapsed time, 120 kilometers in exactly one hour.

Each car had a velocity of 120 km/hr. Nothing traveled 240 km/hr. You would be wrong to say, or think the other car was traveling 240 km/hr. Torque proves my point, as the torque on the axles on each car can be measured, and calculated into Power, which is equal to work/time, work being equal to force*distance. Each engine is doing work, as the crank has a load on it (torque) and it is spinning at an RPM. 1 HP=550 ft-lb of work per second, or HP=Torque*RPM/5252
 
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Motor Daddy said:
An object's velocity is not dependent on another object. Distance and time are not dependent on objects.
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Try this scenario: you are somewhere in the vacuum of space, and there are no visible objects in view. Can you tell if you have any velocity?
Or, does determining your velocity require the existence of at least one other object that you can locate?
 
Originally Posted by Motor Daddy
Let's take your 240 km/sec scenario into consideration.
There is a straight road that is 240 kilometers long. Two cars (one from each end) are traveling at the same velocity towards the midpoint of the road that is 120 kilometers from each end of the road. ... They impact each other exactly at the midpoint ... Each car traveled the same distance in the same elapsed time, 120 kilometers in exactly one hour ... There is nothing that traveled 240 km/hr.
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Please answer the question. The amount of force that is transferred between each automobile (in the event of a car-crash) depends on your answer. It seems to me that there are still a few things you need to learn.
 
arfa brane said:
Try this scenario: you are somewhere in the vacuum of space, and there are no visible objects in view. Can you tell if you have any velocity?

Or, does determining your velocity require the existence of at least one other object that you can locate?
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Velocity is not dependent on another object, it is a measure of distance and time traveled, relative to space, whether you can measure it or not. That is silly to ask me if I can tell if I have relative velocity to another object with no other objects, don't you think?

See my "A train, three clocks, and an observer thread."
 
Acitnoids said:
Please answer the question. The amount of force that is transferred between each automobile (in the event of a car-crash) depends on your answer. It seems to me that there are still a few things you need to learn.
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Sorry, the clock stops when both cars have exactly zero space between them. There is no damage up until then, and we are not looking at the time after that, unless you want to add more time to the exact hour? But, that would make a different velocity, wouldn't it? Darn it!! :rolleyes:
 
Motor Daddy said:
That is silly to ask me if I can tell if I have relative velocity to another object with no other objects, don't you think?

See my "A train, three clocks, and an observer thread."
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Well, why did you say an object's velocity isn't dependent on another object? Obviously determining velocity does require other objects, objects which are visible or detectable somehow.
 
Motor Daddy said:
Velocity is not dependent on another object, it is a measure of distance and time traveled, relative to space, whether you can measure it or not.
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How do you measure distance or time relative to empty space?
Velocity is not relative velocity.
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Yes, it is. All velocities are relative.
 
Light travels at ~186,000 mi/sec, correct?
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Yes, but so what? All that means is that light has an absolute maximum velocity in a vacuum.
The speed of light is lower in a dense medium, like transparent glass say.

So light also has a velocity which is relative to the (refractive index of the) medium it propagates in.

Do you know how to determine the speed of light using only light, and no other "objects"? You realise the speed of light is calculated relative to fixed points, which also coincide with charged particles, like electrons?
 
arfa brane said:
Yes, but so what? All that means is that light has an absolute maximum velocity in a vacuum.
The speed of light is lower in a dense medium, like transparent glass say.

So light also has a velocity which is relative to the (refractive index of the) medium it propagates in.
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We'll just stick to the speed in a vacuum.

If a light was emitted at 12:00:00, how far did it travel in one second?
 
I thought we were going to stick with the speed of light in a vacuum.

Light propagates independently of time, we can calculate the speed of light because we know how to measure distance, between objects that light travels from and to.
Light has no "frame of reference", so we impose an external one for it. But this is for our benefit--we need to know about distance and time, light just "travels".
 
arfa brane said:
I thought we were going to stick with the speed of light in a vacuum.

Light propagates independently of time, we can calculate the speed of light because we know how to measure distance, between objects that light travels from and to.
Light has no "frame of reference", so we impose an external one for it. But this is for our benefit--we need to know about distance and time, light just "travels".
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Light travel time defines distance, try again!
 
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