Delisle to Kelvin
°De
K
Conversion History
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|---|---|---|
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Quick Reference Table (Delisle to Kelvin)
| Delisle (°De) | Kelvin (K) |
|---|---|
| 0 | 373.15 |
| 94.5 | 310.1500000000000063 |
| 120 | 293.150000000000008 |
| 150 | 273.15000000000001 |
| 200 | 239.81666666666668 |
| 300 | 173.15000000000002 |
About Delisle (°De)
The Delisle scale (°De) is a historical temperature scale with an inverted direction: higher Delisle values mean colder temperatures. Created by French astronomer Joseph-Nicolas Delisle in 1732, it sets 0°De at the boiling point of water and counts upward as temperature falls; the freezing point is 150°De. This inversion arose because Delisle calibrated his mercury thermometer so that mercury contracted with cooling, measuring degrees of cooling from the boiling point rather than degrees of warmth above a cold reference. The scale was used extensively in Russia for most of the 18th century, notably by Mikhail Lomonosov, before being replaced by Celsius. Today it is an educational curiosity with no practical use.
Boiling water is 0°De; freezing is 150°De. A typical room at 20°C is 120°De. Absolute zero is approximately 559.73°De.
Etymology: Named after Joseph-Nicolas Delisle (1688–1768), a French astronomer who worked in St. Petersburg at the invitation of Peter the Great from 1726. He devised the scale in 1732 while in Russia, where it was adopted and remained in scientific use until the late 18th century when Celsius became standard.
About Kelvin (K)
The kelvin (K) is the SI base unit of thermodynamic temperature. Unlike Celsius and Fahrenheit it has no degree symbol — temperatures are written "310 K", not "310°K". Kelvin is an absolute scale: 0 K is absolute zero, the theoretical lower bound of temperature where molecular motion effectively ceases. Since the 2019 SI redefinition, the kelvin is fixed by the Boltzmann constant (k = 1.380649 × 10⁻²³ J/K). Kelvin and Celsius share the same degree size — a change of 1 K equals a change of 1°C — making conversion straightforward: K = °C + 273.15. Kelvin is used in physics, chemistry, astronomy, and engineering thermodynamics.
The surface of the Sun is approximately 5,778 K. Liquid nitrogen boils at 77 K (−196°C). The cosmic microwave background temperature is 2.725 K.
Etymology: Named after William Thomson, 1st Baron Kelvin (1824–1907), the Irish-Scottish mathematical physicist who first proposed an absolute temperature scale in 1848. He was ennobled as Baron Kelvin of Largs in 1892, after the River Kelvin in Glasgow near where he worked.
Delisle – Frequently Asked Questions
Why is the Delisle scale inverted?
Delisle calibrated his thermometer by observing how mercury contracted as it cooled from boiling water. He measured degrees of cooling rather than degrees of warmth — the scale counted how far the temperature had dropped from the boiling point. This made 0°De the starting reference (boiling) and larger numbers represent lower temperatures, the opposite of every other common scale.
What is the freezing point of water on the Delisle scale?
The freezing point of water is 150°De. The boiling point is 0°De. The scale spans 150 degrees between freezing and boiling — contrast with 100 degrees in Celsius or 180 degrees in Fahrenheit. To convert: °De = (100 − °C) × 1.5, so 0°C gives (100 − 0) × 1.5 = 150°De.
Who invented the Delisle scale and where was it used?
Joseph-Nicolas Delisle invented the scale in St. Petersburg in 1732, where he had been invited to work by Peter the Great. The scale was adopted by Russian scientists and used throughout the 18th century, particularly by Mikhail Lomonosov. It was later standardized by Joseph-Nicolas's colleague Joseph-Adam Braun, who fixed the two reference points.
How do you convert Delisle to Celsius?
Subtract the Delisle value from 100, then multiply by 2/3. Formula: °C = 100 − (°De × 2/3). For example, 150°De → 100 − (150 × 2/3) = 100 − 100 = 0°C (freezing). For 0°De → 100 − 0 = 100°C (boiling). Remember the scale is inverted: higher Delisle = colder temperature.
What other temperature scales run backwards like Delisle?
Delisle is the only well-known inverted temperature scale, but the concept appears elsewhere. Astronomical magnitude runs backwards (brighter stars have lower numbers). The Scoville scale for chilli heat is not inverted but is logarithmically compressed in a way that confuses people similarly. In thermometry, Delisle stands alone — every other scale (Celsius, Fahrenheit, Kelvin, Rankine, Newton, Rømer, Réaumur) increases with heat. The inversion made Delisle unintuitive, which is a key reason it lost out to Celsius.
Kelvin – Frequently Asked Questions
How close to absolute zero have scientists actually gotten?
In 2021, researchers at the University of Bremen cooled rubidium atoms to 38 picokelvin (38 trillionths of a kelvin above absolute zero) inside a drop tower — the coldest temperature ever achieved. At these extremes, atoms form a Bose–Einstein condensate where quantum effects become visible at macroscopic scales. True 0 K is impossible to reach (the third law of thermodynamics forbids it), but each new record pushes closer, enabling research into superfluidity, quantum computing, and exotic states of matter.
Why do scientists use kelvin instead of Celsius?
Scientific calculations in thermodynamics, astrophysics, and chemistry require an absolute scale with no negative values. Many physical laws — the ideal gas law (PV = nRT), Wien's displacement law, Stefan–Boltzmann law — only work correctly with absolute temperature. Using Celsius would require constant offsets of 273.15.
What is the difference between kelvin and Celsius?
Kelvin and Celsius have identical degree sizes, so a temperature difference of 5 K equals a difference of 5°C. The only difference is the zero point: 0 K = −273.15°C. To convert: K = °C + 273.15. Kelvin has no negative values; Celsius does.
What everyday temperatures are expressed in kelvin?
Kelvin is rarely used in everyday life but appears in lighting (color temperature — a warm white bulb is around 3,000 K, daylight is 6,500 K), industrial processes, cryogenics (liquid helium: 4.2 K; liquid nitrogen: 77 K), and the specification of laser wavelengths and scientific instruments.
What is the coldest naturally occurring temperature in the universe?
The Boomerang Nebula, a protoplanetary nebula about 5,000 light-years away, has a measured temperature of approximately 1 K (−272°C), making it the coldest known naturally occurring place in the universe — colder than the cosmic microwave background (2.725 K).