**The starlight “problem”**

Young Earth Creationist (YEC) claim the universe is 6,000 (or 10,000) years old. If it’s really that young, how can we see stars 30,000, light years away?

**How YEC think General Relativity can help**

In the movie *Interstellar*, Matthew McConaughey misses the teen years of his daughter for having spent too much time on a planet too close to the “Gargantua” Black Hole. Immersed in the formidable *gravitational potential well* of the Black Hole, one single hour on “Miller’s planet” is 7 years on Earth! Gargantua weights about 100 million times more than the sun, Miller’s planet orbits close to it, and yes, according to General Relativity (GR), a planet orbiting Gargantua like “Miller’s planet” does, would enjoy such a crazy time contraction [1].

According to his own wristwatch, Matthew McConaughey spends a little more than 3 hours in this planet. When he comes back to his mother ship, he finds he’s been away for 23 years.

What is then the idea? In *Interstellar*, 1 hour on the planet becomes 7 years out there. And 6,000 years? What would they give out there? 0.36 billion years! Could GR hold the key to thousands of years on Earth being like billions in the rest of the universe?

**Russel Humphreys’ cosmology**

I refer to the cosmology described here.

Humphreys imagine the Earth is at the center of a huge expanding spherical shell surrounded by water. “Using GR”, he derives the gravitational potential *F* **inside the sphere**, at a distance *R* from the Earth, and finds it behaves like

*F = -GM/R*

where *M* is the mass of the shell. This is equation (3) of the article.

Humphreys therefore recovers the kind of gravitational potential well you find around Gargantua, with a time contraction all the more intense than you get close to it.

What is the problem? Humphreys’ gravitational potential is wrong. And trivially wrong. According to the very GR equations Humphreys’ pretends he uses, the gravitational potential *inside* his sphere is just 0. And because of the Birkhoff theorem, there cannot be any other solution in the kind of spherical symmetry Humphreys uses. The potential inside the sphere is zero, and there is no other way it can be. No gravitational potential well. No time dilatation or contraction whatsoever* inside the sphere*.

There’s nothing more to it.

### Footnote

[1] See The Science of Interstellar by Nobel Prize Kip Thorne. The reader will also find more technical data on the same topic here.