Chapter 1 · Topic 1.1 · Prelims + Mains1 of 3
Basics of Science: Method, R&D and SI units
Key points
- Scientific method: observe, hypothesise, test, analyse, repeat.
- A theory is a well-tested explanation, not a guess.
- GERD 0.84% of GDP (2023-24). Private share 51.8% passed government for the first time.
- SI has seven base units, kept by BIPM at Sèvres, France.
- Since 20 May 2019 all base units rest on constants. Kilogram defined by the Planck constant.
- 2022: new prefixes ronna, quetta, ronto, quecto.
Prelims box: facts and traps
| Item | Fact |
|---|---|
| GERD 2023-24 | 0.84% of GDP |
| Private share 2023-24 | 51.8% |
| SI redefinition in force | 20 May 2019 |
| Quetta | 10³⁰ |
- Trap: a theory is not a guess but can still be revised.
- Trap: the old kilogram was platinum with 10% iridium, sanctioned in 1889.
The scientific method and research in India
Science is a way of finding out how nature works by testing ideas against evidence. The scientific method runs in a loop:
- observe something and ask a question,
- propose a hypothesis (a testable guess),
- test it by experiment or more observation,
- analyse the results, and accept, change or reject the hypothesis.
Other scientists must be able to repeat the work and get the same result. If you think a plant grows faster in sunlight, you grow one in sun and one in shade and compare.
A hypothesis that passes many tests and explains a wide range of facts becomes a theory, such as the theory of relativity. A law describes a regular pattern, often as an equation, without saying why it happens. A theory is not a guess. It is the strongest kind of scientific explanation, but it can still be revised by new evidence.
| India’s R&D spending (DST) | 2019-20 | 2020-21 | 2021-22 | 2022-23 | 2023-24 |
|---|---|---|---|---|---|
| GERD (Rs crore) | 1,32,567.01 | 1,27,380.96 | 1,94,810.83 | 2,13,378.12 | 2,44,767. |
| GERD as % of GDP | 0.66 | 0.64 | 0.83 | 0.82 | 0.84 |
| Government share (%) | 66.2 | 63.6 | 54.5 | 52.0 | 48.2 |
| Private share (%) | 33.8 | 36.4 | 45.5 | 48.0 | 51.8 |
Source: DST, Research & Development Statistics 2025-26, as given in a Rajya Sabha reply (PIB, 29 July 2026). Measured. GERD = gross expenditure on research and development.
Mains 2014 asked whether university research is declining because science careers attract fewer people. The DST data show total R&D spending rising to 0.84% of GDP in 2023-24, with the private sector’s share (51.8%) passing the government’s for the first time in the series.
Scientific research in Indian universities is declining, because a career in science is not as attractive as are business professions, engineering or administration, and the universities are becoming consumer-oriented. Critically comment.
SI units and the 2019 redefinition
The International System of Units (SI) is the modern metric system, kept by the International Bureau of Weights and Measures (BIPM) at Sèvres, France. It has seven base units. Every other unit, such as the newton (force) or the watt (power), is built from them (SI Brochure, 9th edition).
| Base quantity | SI unit | Symbol | Now fixed by |
|---|---|---|---|
| Time | second | s | caesium-133 frequency, 9 192 631 770 Hz |
| Length | metre | m | speed of light, 299 792 458 m/s |
| Mass | kilogram | kg | Planck constant, 6.626 070 15 × 10⁻³⁴ J s |
| Electric current | ampere | A | elementary charge |
| Thermodynamic temperature | kelvin | K | Boltzmann constant, 1.380 649 × 10⁻²³ J/K |
| Amount of substance | mole | mol | Avogadro constant |
| Luminous intensity | candela | cd | luminous efficacy of 540 THz light |
Source: BIPM, SI Brochure (9th edition), Table 2 and the definitions of the base units.
In November 2018 the 26th General Conference on Weights and Measures (CGPM) redefined the SI so that all seven base units rest on seven fixed constants of nature, with effect from 20 May 2019 (BIPM). Until then the kilogram was defined by a metal cylinder of platinum with 10 per cent iridium, sanctioned in 1889. A speck of dust on it changed the world’s kilogram. It is now defined by the Planck constant (SI Brochure).
In 2022 the 27th CGPM added four prefixes: ronna (10²⁷), quetta (10³⁰), ronto (10⁻²⁷) and quecto (10⁻³⁰). Data science needed names for quantities beyond 10²⁴ (SI Brochure, Resolution 3 of 2022).
What UPSC asks: Prelims: seven base units, quetta. Mains: GERD 0.84% of GDP.
Mains box: analysis and answer points
- R&D in India: low GERD, rising private share, university research.
- Measurement: why fixed constants beat physical objects.
Practice
Write an answer
In 150 words, explain the significance of Basics of Science with one recent example.
Flashcards (9)
Steps of the scientific method?
Observe, question, hypothesise, test, analyse, revise.
Is a theory a guess?
No: a well-tested explanation that can still be revised.
India's GERD as % of GDP, 2023-24?
0.84% (DST).
Private share of R&D spending, 2023-24?
51.8%.
How many SI base units?
Seven.
SI unit of luminous intensity?
Candela.
Constant that defines the kilogram?
Planck constant.
Date the revised SI took effect?
20 May 2019.
Prefixes added in 2022?
Ronna, quetta, ronto, quecto.
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