Is this the one way speed of light?

In summary, the conversation discusses the concept of determining the distance between two light pulses emitted by a stationary observer. The observer marks out 10 metres and places himself at the halfway mark. If the pulses align with the marked distance, the distance between them is 10 metres. However, the observer must adjust the marked distance until it aligns with the light pulses to accurately determine the distance. The conversation also delves into the issue of measuring the one-way speed of light and how it is dependent on the chosen definition of simultaneity.
  • #1
DAC
99
2
Hello PF.
A stationary observer generates two pulses of light. The pulses are 2 seconds apart according to his watch.

What is the distance between the two pulses? Assume he marks out 10 metres and places himself half way at the 5 metre mark. If the light pulses go past and align with the 10 metre marks, the distance between the light pulses is 10 metres. Being equidistant from the 10 metre marks he records simultaneous measurements. The odds are the light and the 10 metre marks won't al;gn. But the 10 metres can be altered. ( 9,8,11,12 etc. ) until they align with the light pulses. thereby giving the distance between the pulses.
With distance and time we have speed. One way speed?
 
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  • #2
The odds are the light and the 10 metre marks won't align
Odds ? There is no probability involved !
You just before this wrote he records simultaneous measurements ?
 
  • #3
DAC said:
Hello PF.
A stationary observer generates two pulses of light. The pulses are 2 seconds apart according to his watch.

What is the distance between the two pulses? Assume he marks out 10 metres and places himself half way at the 5 metre mark. If the light pulses go past and align with the 10 metre marks, the distance between the light pulses is 10 metres. Being equidistant from the 10 metre marks he records simultaneous measurements. The odds are the light and the 10 metre marks won't al;gn. But the 10 metres can be altered. ( 9,8,11,12 etc. ) until they align with the light pulses. thereby giving the distance between the pulses.
With distance and time we have speed. One way speed?
I guess I'm not following what you are saying. You say "the distance between the light pulses is 10 meters", but you have stated that the distance between the light pulses is 2 light seconds. Compared to 2 light seconds, 10 meters is approximately zero.
 
  • #4
DAC said:
...Being equidistant from the 10 metre marks he records simultaneous measurements...

How do you establish that the measurements are in fact simultaneous? All techniques for determining simultaneity are directly or indirectly based on the assumption that the one-way speed of light is equal to the two-way speed.

The "one-way speed of light problem" isn't that we can't "measure" the one-way speed of light. We can, just as you did: choose a definition of "simultaneous" so that we can measure the time between emission and reception and then speed=distance/time will see us home. The problem is that when our measured one-way speed comes out the same as the measured two-way speed that doesn't tell us that the speed of light is the same in both directions. It tells us that we chose a definition of "simultaneous' that assumed that the two speeds are equal.
 
  • #5
DAC said:
If the light pulses go past and align with the 10 metre marks,
What does this mean?
 

FAQ: Is this the one way speed of light?

What is the one way speed of light?

The one way speed of light is the speed at which light travels from one point to another in a vacuum without any external influence affecting its speed.

Why is the one way speed of light important?

The one way speed of light is important because it is a fundamental constant in the universe and is used in many scientific theories and equations. It also plays a crucial role in our understanding of the nature of space and time.

How is the one way speed of light measured?

The one way speed of light is measured using various methods such as the time-of-flight method, which measures the time it takes for light to travel from one point to another, or the interferometry method, which compares the speed of light in different directions.

Is the one way speed of light constant?

According to the theory of relativity, the one way speed of light is constant, meaning it does not change regardless of the observer's frame of reference. This has been confirmed by numerous experiments and is considered a fundamental law of physics.

Can the one way speed of light be exceeded?

Currently, there is no evidence to suggest that the one way speed of light can be exceeded. According to the theory of relativity, the speed of light is the maximum speed at which anything can travel in the universe. However, some theories, such as quantum entanglement, suggest that information can appear to travel faster than the speed of light, but this does not violate the one way speed of light as it does not involve any physical object or energy.

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