Is The Planck Scale Really The Smallest?

When we read articles or watch videos on many fancy science topics, we hear a lot of people saying that the planck length is the shortest length, planck time is the shortest time, planck energy is the highest energy, etc. But all these are NOT necessarily true. I will explain the reason here.

Before we understand the reason, let us understand more about the planck scale. Suppose, let us ask a question. How much distance is 1m? Scientifically, 1m is defined as the distance travelled by a photon(light) in 1/ 299,792,458 of a second. But, if some aliens came to us and ask how much is 1m, it is very difficult to explain how much a second is and we can argue about the results also.

To overcome these problems, Max Planck came up with a solution by inventing what he called “natural units “. He write down units of time, length, space, energy, etc by using only constants. The constants are the speed of light, gravitational constant, reduced Planck constant, Bolztann constant, Coulumb constant. By taking different combinations of these variables, one can find Planck units, which are truly universal. For instance, by taking √ ħG/c3 , one gets a length. This length is the Planck length, and it is 1.6 * 10^-35 meters and Planck time: 5.4 * 10^-43 second.

So, what the Planck constants mean is that they are fundamented units of time, length, etc. If say an object is 2 Planck length apart and if I tell this to an alien, he would agree about the result and he would easily understand. Because the Planck length is the solution of this √ ħG/c3 and the variable involved are all constants. So the Planck length would be the same everywhere in the universe. This also applies to other Planck constants.

And where does that shortest time, length etc idea come from? It all started in 1964 when a chemist Alden Mead published an article named ‘Possible Connection Between Gravitation and Shortest Length’. In his article, he does not mention anything about Planck scale being the smallest, shortest or whatsoever. Whatat he expressed in his article is that at the planck scale, the effect of gravity is so strong that it is no longer negligible. So we no need a Theory Of Quantum Gravity to make the equations work.

What all this means is that at the Planck scale, the effect of gravity is so strong that our current understanding of physics breaks down and needs to be replaced by Theory Of Quantum Gravity. The reason why people call this the smallest scale is because it is the smallest scale up to which our current understanding of physics works. Below this scale, it breaks down.

Lastly, the Planck scale is NOT NECESSARILY the shortest time, shortest length, etc. Instead, it is the scale at which our current understanding must break down. There may need be smaller time, legth, etc but we need a Theory Of Quantum Gravity to understand that.