How Are Planck Time and the Expression \(\sqrt{\frac{\hbar c^5}{G}}\) Related?

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take this derivation

\hbar c = GM^2

multiply c^4 on both sides

\hbar c^5 = GM^2c^4

rearrange

\frac{\hbar c^5}{G} = M^2c^4

Take the square root makes

\sqrt{\frac{\hbar c^5}{G}} = E

Now this \sqrt{\frac{\hbar c^5}{G}} expression inside the radical expression is fascinatingly similar to the Planck time \sqrt{\frac{\hbar G}{c^5}}. I began to wonder if there was any physical significance between the two? Is there any?

 
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What you wrote down is call the Planck Energy. It is a quantity with dimensions of energy that you can get, as you saw, by simply rearranging the universal constants. The Planck time, length, mass, etc are scales where people expect that you can't talk about gravity and quantum mechanics separately.
 
So it is... I never thought to check the plank energy. I found this independantly lol
 
I have a new question, why does c^5 show up in the calculations, is there a significant reason for this, other than balancing the dimensions?
 
Insights auto threads is broken atm, so I'm manually creating these for new Insight articles. Towards the end of the first lecture for the Qiskit Global Summer School 2025, Foundations of Quantum Mechanics, Olivia Lanes (Global Lead, Content and Education IBM) stated... Source: https://www.physicsforums.com/insights/quantum-entanglement-is-a-kinematic-fact-not-a-dynamical-effect/ by @RUTA
If we release an electron around a positively charged sphere, the initial state of electron is a linear combination of Hydrogen-like states. According to quantum mechanics, evolution of time would not change this initial state because the potential is time independent. However, classically we expect the electron to collide with the sphere. So, it seems that the quantum and classics predict different behaviours!
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