Editing Human scale (section)

== Science vs. human scale ==

Many of the objects of scientific interest in the universe are much larger than human scale (stars, galaxies) or much smaller than human scale (molecules, atoms, subatomic particles).

Similarly, many time periods studied in science involve time scales much greater than human timescales ([[geologic timescale|geological]] and [[cosmological time scale]]s) or much shorter than human timescales (atomic and subatomic events).

Mathematicians and scientists use very [[large number|large]] and small numbers to describe physical quantities, and have created even larger and smaller numbers for theoretical purposes.

Human scale measurements, however, are more in the order of:

* [[Distance]]: [[1 E0 m|one to two metres]] ({{cvt|3-6|ft|m|1|order=flip|disp=or}} &ndash; human arm's reach, stride, height)
* [[Attention span]]: seconds to hours
* [[Life expectancy|Life span]]: 75 years (mean life expectancy at birth)
* [[Mass]]: [[1 E0 kg|kilograms]] &ndash; most typically, for newborns from about {{convert|3|-|4|kg|lb|0|abbr=on}} for a human adult their weight range is about {{convert|50|-|100|kg|lb|sigfig=1|abbr=on}} 
* [[Force]]: [[Newton (unit)|newton]]s (e.g. the weight of a human on Earth, on the order of several hundred newtons, or about 100&ndash;200&nbsp;lb<sub>f</sub>)
* [[Pressure]]: one [[Atmosphere (unit)|standard atmosphere]] (average pressure on Earth at sea level, approximately {{convert|100|kPa|inHg|sigfig=1|abbr=on|lk=in|disp=or}})
* [[Temperature]]: around {{convert|300|K|C F|abbr=on|lk=in}} (room temperature); {{convert|250|to|320|K|C F|abbr=on|-1}} (normal range of temperatures in most inhabited regions of Earth)
* [[Energy]]: typical adult human energy intake is around {{convert|10|MJ|kcal|abbr=off}} per day