c = 299 792 458 m/s and uncertainty

DonnieD

c is 299 792 458 m/s without uncertainty? doesn't work the Heisenberg uncertainty principle for fotons?

AlphaNumeric

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.

Born2Perform

Quote by AlphaNumeric

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?

russ_watters

No, the meter is defined as the distance light travels in a specified time.

http://www.mel.nist.gov/div821/museum/timeline.htm

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DonnieD	c = 299 792 458 m/s and uncertainty Tweet c is 299 792 458 m/s without uncertainty? doesn't work the Heisenberg uncertainty principle for fotons?

AlphaNumeric	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.

russ_watters Mentor	c = 299 792 458 m/s and uncertainty No, the meter is defined as the distance light travels in a specified time. http://www.mel.nist.gov/div821/museum/timeline.htm