# Scientific measurement standards

• mes314159
In summary, the conversation discusses the standard values for scientific constants, such as the meter, which is defined with respect to the distance light travels in a certain amount of time. However, due to relativity, the speed of light is constant in a vacuum, but distance and time can be affected by relative movement and gravitational fields. The question is whether the standard meter is defined with respect to a specific location on earth, taking into account variations in relative position and gravitational influences. It is explained that observers traveling in different locations may not notice these effects as long as they are not accelerating, but corrections need to be made for accurate measurements. The solution to this issue is the use of GPS technology.

#### mes314159

This is not a question about relativity per se, but relates to it sufficiently I hope. Standard values for many scientific constants are defined, and ideally in the most universal way possible. For example, the standard length unit, a meter, is defined with respect to the distance light travels in certain amount of time, that being defined by a certain number of oscillations of an atomic "clock". By relativity, the speed of light is constant in a vacuum, however distance and time are affected by relative movement and gravitational fields. So my question is, is the standard meter defined with respect to a particular location on earth, with the understanding that it will vary according to relative position of another location either moving or under different gravitational influences (like further away from the center of the earth, or on the moon)? Or are the necessary corrections beyond the requirements of most practical scientific or engineering applications?

An observer who is "traveling" or under a gravitational influence cannot tell that his distances or time or speed of light measurements are affected by those factors as long as he is not accelerating (changing his speed or direction). For example, the atomic clocks at Greenwich, England run at a different rate than identical ones at Boulder, CO, but everything is consistent at each location. Meter sticks made at each location based on a clock and the speed of light at each location will be the same length when brought together. But we can tell that the clocks are running at different speeds and corrections need to be made so that we all use a common interval for a second independent of our elevation. GPS is the modern solution to this problem.

That does indeed make sense. As long as the 'internal physics' of the clocks is constant (whatever that means) meters generated at different locations will be the same when brought together. That's the 'best' one can do. Thanks for clarifying.

## 1. What are scientific measurement standards?

Scientific measurement standards are a set of internationally recognized units of measurement that are used by scientists to ensure consistency and accuracy in their experiments and research. These standards are based on fundamental physical quantities such as length, mass, time, temperature, and electric current.

## 2. Why are scientific measurement standards important?

Scientific measurement standards are important because they provide a common language for scientists to communicate their findings and results. They also ensure that experiments and research conducted by different scientists can be compared and replicated accurately. Without these standards, there would be no way to ensure the reliability and validity of scientific data and conclusions.

## 3. How are scientific measurement standards established?

Scientific measurement standards are established through international agreements and conventions, such as the International System of Units (SI). These standards are based on precise and unchanging physical constants or fundamental units, which are then used to define all other units of measurement.

## 4. Are scientific measurement standards constantly changing?

No, scientific measurement standards are not constantly changing. They are based on fundamental physical constants and are carefully defined and maintained to ensure consistency and accuracy. However, as technology and scientific understanding advance, some standards may be refined or updated to reflect more precise measurements.

## 5. How are scientific measurement standards used in everyday life?

Scientific measurement standards are used in everyday life in a variety of ways, such as in cooking, construction, and transportation. For example, measurements of volume, weight, and distance are all based on scientific measurement standards. In addition, many consumer products, such as food and medications, are required to have accurate and standardized measurements for consumer safety and health.