# Planck scale dimensions

1. Dec 27, 2009

### Orion1

Planck energy:
$$E_P = m_P c^2 = \sqrt{\frac{\hbar c^5}{G}}$$

$$r_G = \frac{r_s}{2} = \frac{G m_P}{c^2}$$

Gravitational radius is equivalent to Compton wavelength:
$$r_G = \overline{\lambda}_C$$

$$\frac{G m_P}{c^2} = \frac{\hbar}{m_P c}$$

Planck force is a constant in the Einstein field equation:
$$F_P = \frac{E_P}{r_G} = m_P c^2 \left( \frac{c^2}{G m_P} \right) = \frac{c^4}{G} = \frac{8 \pi T_{\mu \nu}}{G_{\mu\nu}}$$

The maximum ratio of energy per gravitational length:
$$\boxed{\frac{c^4}{G} = \frac{8 \pi T_{\mu \nu}}{G_{\mu\nu}}}$$

Are Planck scale dimensions the maximum limits in the Universe?

Reference:
http://en.wikipedia.org/wiki/Planck_force" [Broken]
http://en.wikipedia.org/wiki/Planck_mass" [Broken]
http://en.wikipedia.org/wiki/Planck_energy" [Broken]

Last edited by a moderator: May 4, 2017
2. Dec 30, 2009

### Polyrhythmic

Where did you get that expression for the quotient of the Stress-enery-tensor and the Einstein-tensor from? As far as I know, it's not valid to divide two tensor-valued quantities.

3. Dec 30, 2009

### Orion1

From Einstein's field equation:
$$G_{\mu \nu} = \frac{8 \pi G}{c^4} T_{\mu \nu}$$

It is not possible to divide tensors. However, It is possible to divide the solutions after the tensors have been solved for a specific solution.

For example:
$$\boxed{\frac{c^4}{G} = \frac{8 \pi T_{r r}}{G_{r r}}} \; \; \; \mu = \nu$$

Are Planck scale dimensions the maximum limits in the Universe?

Last edited: Dec 30, 2009