Tomilin (opens in new tab) of the Moscow Institute for the History of Science and Technology. Is Planck time real?īecause the Planck time is so impractically small, it was largely ignored by scientists prior to the 1950s, according to K.

It’s the time it takes light to travel one Planck length, which is around a hundredth of a millionth of a trillionth of the diameter of a proton, according to Symmetry magazine (opens in new tab). The Planck time has no fewer than 43 zeroes. A nanosecond, often used colloquially to mean “a very short time,” is 0.000000001 seconds, with 8 zeros between the decimal point and the first significant figure. Whichever value is used, the result is a time interval that is unimaginably tiny in the context of everyday experience. The larger value uses Planck’s original quantity, h, while the smaller, more common value uses a parameter called h-bar, which is h divided by 2 pi. As explained on Eric Weisstein’s World of Physics (opens in new tab) site, this is due to the use of two different versions of Planck’s constant. In other sources, including Planck’s original paper, you may find a slightly bigger value around 1.35 × 10^-43 seconds. National Institute for Standards and Technology (opens in new tab) gives the value of the Planck time as 5.391247 × 10^-44 seconds. The Planck time equation Planck time in seconds Our particular interest here is in the last of these, but there’s a close relationship between the last two: the Planck length is equal to the Planck time multiplied by the speed of light. These basic units are referred to as the Planck mass, Planck length and Planck time. Taking these three constants as his starting point, Planck was able to find a new set of measurement units in which they’re all precisely equal to one. Usually represented by the letter h, it’s the ratio of a photon's energy to its frequency, with units of kilograms multiplied square meters per second. The third parameter was a brand-new constant Planck himself had just discovered, now known simply as Planck’s constant. This was known to be an important constant even in 1899, despite the fact that Einstein’s theory of relativity, with which it’s closely associated, still lay several years in the future. The second parameter Planck chose was the speed of light c, in meters per second. As such, he’s rightly described as the father of quantum physics (opens in new tab). According to the European Space Agency (opens in new tab), which named its Planck spacecraft after him, the breakthrough came in 1900 when he discovered that energy can only be transmitted in small packets of prescribed size, which he termed “quanta.” This was decades before the likes of Werner Heisenberg and Erwin Schrödinger discovered all the quantum weirdness we’re familiar with today, but none of that would have been possible if Planck hadn’t paved the way first. Max Planck may not be a household name, but he gave the world a household phrase: quantum theory. Planck wanted to find a more “natural” set of units in which G, and similar fundamental constants, are exactly equal to 1. In these units, G – which is one of the most fundamental numbers in the universe – has the arbitrary-looking value of 0.0000000000667. In Newton’s equation for the force of gravity, for example, the gravitational constant G has brain-twisting units of “cubic meters per kilogram per second squared,” according to Swinburne University (opens in new tab). The math can still get tortuously complicated.

Scientists tend to use SI units (opens in new tab) of kilograms, meters and seconds, because they simplify complex calculations – but only up to a point. We use whatever is convenient – ounces or tons for mass, miles or inches for distance, minutes or days for time. In everyday use, measurement units are no big deal. The Planck time was first described in a scientific paper written by Planck in 1899, in a section called “Natural Measurement Units” (the paper, in German, can be found at the Biodiversity Heritage Library (opens in new tab)).

Space in time definition