why might using the speed of light to determine the length of the meter be more reliable than using a measured distance around the earth
The measured distance around the earth? I don't know if anyone has measured it to much accuracy. The speed of light is known to over eight significant digits.
and the distance around the earth would be measured how? ...
Using the speed of light to determine the length of the meter can be more reliable than using a measured distance around the Earth due to a few reasons:
1. Precision: Measuring the speed of light is extremely precise, as it has been extensively studied and refined over many years. Since the speed of light in a vacuum is a fundamental constant of nature, it provides a consistent and stable reference point for defining a unit of length.
2. Universality: The speed of light is a universal constant that does not depend on the specific characteristics of a location or environment. It is the same value regardless of where or when it is measured, making it an ideal reference for establishing a standardized unit of length worldwide.
3. Reproducibility: The measurement of a specific distance around the Earth can be challenging and subject to various uncertainties. There might be inaccuracies due to variations in the Earth's shape, rotating reference frames, or difficulties in precisely determining the path and distance of the measurement. On the other hand, measuring the speed of light can be replicated in a controlled laboratory environment, allowing for more consistent and reliable results.
To determine the length of the meter using the speed of light, the method involves defining the meter as the distance traveled by light in a vacuum in precisely 1/299,792,458 of a second. This definition ensures that the meter is directly related to a fundamental constant of nature, providing a reliable and stable reference point for measurements.