C = 299 792 458 m/s and uncertainty

In summary, the speed of light, c, is defined as 299 792 458 m/s without uncertainty. This is because the distances typically involved in measuring c are large enough that quantum fluctuations can be ignored. Additionally, the length of 1m is defined by the distance light travels in a certain amount of time, so we are effectively defining light's speed rather than measuring it. While we do define 1m, we still need to measure how long it takes for light to cross 1m. However, the meter is defined as the specific distance light travels in a specified time, so it is an exact measurement of c.
  • #1
DonnieD
9
0
c is 299 792 458 m/s without uncertainty? doesn't work the Heisenberg uncertainty principle for fotons?
 
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  • #2
The distances typically involved in measuring c are sufficently big that quantum fluctuations are ignored.

Also, the length of 1m is defined by the distance light travels in a certain amount of time. Because of this definition, we're effectively defining light's speed, not measuring it, so it is exact.
 
  • #3
AlphaNumeric said:
Also, the length of 1m is defined by the distance light travels in a certain amount of time. Because of this definition, we're effectively defining light's speed, not measuring it, so it is exact.
we define 1m, but we must still measure in how much time light crosses 1m; we measured c but it can be less or more, right?
 

1. What does the value "C = 299 792 458 m/s" represent?

The value "C = 299 792 458 m/s" is the speed of light in a vacuum, also known as the constant "c" in the equation E=mc². It is a fundamental physical constant that plays a crucial role in many areas of physics, such as relativity and electromagnetism.

2. Why is the speed of light considered a constant?

The speed of light is considered a constant because it has been measured to be the same value in all inertial reference frames, regardless of the motion of the observer or the source of light. This is a fundamental principle of Einstein's theory of special relativity.

3. How was the value of "C = 299 792 458 m/s" determined?

The value of "C = 299 792 458 m/s" was determined through various experiments, including the famous Michelson-Morley experiment and more recent measurements using high-precision lasers. It is now defined by the International System of Units (SI) as the exact value of the speed of light in a vacuum.

4. What is the uncertainty associated with the value of "C = 299 792 458 m/s"?

The uncertainty associated with the value of "C = 299 792 458 m/s" is extremely small, on the order of 10^-9 m/s. This is because the speed of light is a well-established and precisely measured value, and any uncertainty in its measurement has been reduced through improved technology and techniques.

5. How does the uncertainty of "C = 299 792 458 m/s" affect scientific research and experiments?

The uncertainty of "C = 299 792 458 m/s" plays a crucial role in many scientific research and experiments, particularly in fields such as quantum mechanics and cosmology. It is taken into account when making calculations and interpreting data, and any changes or improvements in its measurement can have significant implications for our understanding of the universe.

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