https://arxiv.org/abs/1504.07627

We report a new area law in General Relativity. A future holographic screen is a hypersurface
foliated by marginally trapped surfaces. We show that their area increases monotonically along the
foliation. Future holographic screens can easily be found in collapsing stars and near a big crunch.
Past holographic screens exist in any expanding universe and obey a similar theorem, yielding the
first rigorous area law in big bang cosmology. Unlike event horizons, these objects can be identified
at finite time and without reference to an asymptotic boundary. The Bousso bound is not used, but
it naturally suggests a thermodynamic interpretation of our result.

ChrispenEvan said:

https://arxiv.org/abs/1504.07627

We report a new area law in General Relativity. A future holographic screen is a hypersurface
foliated by marginally trapped surfaces. We show that their area increases monotonically along the
foliation. Future holographic screens can easily be found in collapsing stars and near a big crunch.
Past holographic screens exist in any expanding universe and obey a similar theorem, yielding the
first rigorous area law in big bang cosmology. Unlike event horizons, these objects can be identified
at finite time and without reference to an asymptotic boundary. The Bousso bound is not used, but
it naturally suggests a thermodynamic interpretation of our result.

Let me look at this tomoz

ChrispenEvan said:

https://arxiv.org/abs/1504.07627

We report a new area law in General Relativity. A future holographic screen is a hypersurface
foliated by marginally trapped surfaces. We show that their area increases monotonically along the
foliation. Future holographic screens can easily be found in collapsing stars and near a big crunch.
Past holographic screens exist in any expanding universe and obey a similar theorem, yielding the
first rigorous area law in big bang cosmology. Unlike event horizons, these objects can be identified
at finite time and without reference to an asymptotic boundary. The Bousso bound is not used, but
it naturally suggests a thermodynamic interpretation of our result.

Bloody ‘ell. What a fabby random word generator. Where’d ya get it?

ChrispenEvan said:

https://arxiv.org/abs/1504.07627

We report a new area law in General Relativity. A future holographic screen is a hypersurface
foliated by marginally trapped surfaces. We show that their area increases monotonically along the
foliation. Future holographic screens can easily be found in collapsing stars and near a big crunch.
Past holographic screens exist in any expanding universe and obey a similar theorem, yielding the
first rigorous area law in big bang cosmology. Unlike event horizons, these objects can be identified
at finite time and without reference to an asymptotic boundary. The Bousso bound is not used, but
it naturally suggests a thermodynamic interpretation of our result.

I almost understand this. I’ve forgotten what a foliation … no I haven’t … a foliation is a set of surfaces perpendicular to a vector field. For example, in Newtonian physics, the speed and direction of movement is a vector. The set of surfaces perpendicular to that, … perhaps easiest to think of a foliation as the set of surfaces of constant “potential energy”. For the gravity of the Earth, each surface is nearly a sphere.

The best known “holographic screen” is an event horizon. But is general it may include surfaces that are parallel to the event horizon or will develop into an event horizon. If you know Green’s theorem (standard maths in an engineering course) then you know that properties on a surface (the so-called holographic screen) can be used to determine what is happening in the volume enclosed by that surface.

This paper seems to be straight general relativity, a breath of fresh air these days where there are so many papers deriving results from alternative false theories of gravity.