Laboratory experiments are an important way of making sensory descriptions that are scientific. Different people in different societies may have profoundly different ways of seeing things. So we make measurements to cope with perceptual variation. Mensuration is also a way to transcend personal sensory limitations. Indeed, a systematic quantitative approach to observation is crucial for objectifying the description of sensation. Measurement techniques can be quite arbitrary to start, for example determinations of length began by referring to somebody’s foot. But nonetheless observational methods have become very accurate and dependable because experimental physicists have invested an enormous effort in developing calibration standards and high precision techniques. For example, atomic clocks can be used to make time measurements that are good to about one part in . By comparison, in 2013 the US economy was 17 trillion dollars or about cents. So physicists can be fussy in a way that is like counting every dime spent in the USA per year. When we speak of doing laboratory experiments, we mean that observations are being made and reported in this fastidious style.
|not seeing the Sun||(MeV)|
For EthnoPhysics, discussing laboratory practice starts with the reference sensations that are benchmarks from which all perceptions are judged and recognized. These sensations are mathematically represented by constants. And sometimes, the constants express calibration standards. See the accompanying table for examples where notes the temperature and marks the internal energy. Quarks are represented by , or for the bottom, charmed and down types. Numerical values for these constants are established by convention, and are without any claim of universal validity. They can be altered by collective agreement if expedient. So, due to the variety of possibilities, a statement of measurement units is usually included with any complete experimental report. As measurement techniques become more refined, calibration standards are adjusted, and so these constants actually represent historical standards. For example, the internal energy of a down-quark is almost always taken as zero, as shown in the table. But precise observations of hydrogen show a tiny value of a few micro electronvolts.