The World's Most Sensitive Thermometer Is Made From Light

A team of researchers has made the world's most sensitive thermometer at room temperature, which is three times more precise than any to go before it—and it's made of light.

The researchers claim that their new thermometer is able to measure temperature with a staggering precision of 30 billionths of a degree. While it's possible to make more accurate measurements at extremely low temperatures close to absolute zero, this is the first time such precision has been achieved at room temperature.

The thermometer injects red and green light into a highly polished crystalline disk, through which they travel at slightly different speeds depending on the temperature. When it's warmer, the red light slows slightly compared to the green. By forcing it to travel around the edge of the disk thousands of times, it's possible to measure the differences—and use it to measure temperature with extreme precision. Professor Andre Luiten, one of the researchers, explains what the finding means:

"We've been able to measure temperature differences to 30 billionths of a degree in one second. To emphasise how precise this is, when we examine the temperature of an object we find that it is always fluctuating. We all knew that if you looked closely enough you find that all the atoms in any material are always jiggling about, but we actually see this unceasing fluctuation with our thermometer, showing that the microscopic world is always in motion."

The new device might not just be limited to measuring temperature though: it could in theory be used to sense pressure, humidity, force or even the presence of specific chemicals. So that's what the researchers plan to do now. [Physical Review Letters via PhysOrg]