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Here, you can find scientific data resources, including peoples' view on various topics on science and technology. This section is divided into three category: 1. Science Constants, 2. Unit Conversions and 3. Survey and Statistics.

1. Science Constants

Quick search. Type in a keyword then click Search button.

All constants are categorized into five different groups as shown on the right. The constants are listed in alphabetical order in each group.

Universal - Fundamental invariant quantities that usually appear in basic theoretical equations in all aspects of science.
Electromagnetic - General electronic and magnetic behavior.
Atomic and nuclear - Values relate to atomistic world, including sub-particles.
Physico-chemical - Quantities usually encounter in chemical physics.
Mathematics - Mathematical constants with no units, usually can be derived from mathematical equations.

universal constants




atomic and nuclear

Atomic and nuclear

chemical physics


mathematical constants


2. Unit Conversions

Quick unit search. Type in a keyword, select unit name, symbol or application (category) type then click Search button.

Name Symbol Application

All measurement units are categorized into six different groups as shown on the right. The quantities are listed in alphabetical order in each group, with some examples of unit application (category) type are also given.

Physical dimension - Length, area, volume.
Heaviness - Mass, weight etc.
Electromagnetic - Electronic, magnetic
Chemical & physical - Energy, power, force, heat, thermodynamic etc.
Irradiation - emission of light, radioactivity etc.
Duration - Time, year, era etc.

Click here to find out more about the SI units (see Note below).

physical dimension

Physical Dimensions

mass, weight


electronic, magnetic


chemical physics

Chemical & physical

mathematical constants


mathematical constants


3. Survey and Statistics

This section contains poll results on views and opinions of some of the visitors to this web site. The poll questions are largely orientated towards popular topics in science and technology. I would like to give my thanks to those who have participated in the poll! New poll questions will be posted from time to time, so do remember to cast your vote!

Space Science - Space exploration, policy and astronomy.
Environment - Renewable energy, policy, problems.
Global & Society - Issues concerning the whole world and to the society.
Education - Issues regarding science in education.

Space science

Space Science



Global and society

Global & Society




The science constant values obtained from 1998 Committee on Data for Science and Technology (CODATA) recommeded values. Derivation of values can be found in (1) Journal of Physical and Chemical Reference Data, vol. 28, No. 6, p1713-1852 (1999) and (2) Reviews of Modern Physics, vol. 72, No. 2, p351-495 (2000). The last 2 digits in brackets are the uncertainty of values. Values list are exact if they do not have this uncertainty.

The International System of Units (Le Systeme International d'Unités) or the SI units are the standardized, internationally accepted units. All other informal or colloquial units listed are shown in the SI unit equivalent. Up to date (2002), there are 7 fundamental or base SI units and 2 supplementary SI units of which all known units can be derived.

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