How to split overlapping polygon isochrones in QGIS?

You can use only one align environment that will break across pages with the \allowdisplaybreaks switch. Note that if you use empheq with option overload, you cannot break across pages anymore. To do so, you will have to use the AmSalign environment. I also replaced array with bmatrix:

\documentclass[12pt]{article}
\usepackage{amsmath}

\begin{document}
\mbox{}
\vskip10cm
\allowdisplaybreaks
\begin{align*}
P & =
\begin{bmatrix}
P_{11} & P_{12} & P_{13} & P_{14} \\
P_{21} & P_{22} & P_{23} & P_{24} \\
P_{31} & P_{32} & P_{33} & P_{34} \\
\end{bmatrix}
\intertext{where}
P_{11} &= XXXXXXXXXXXXX \\
P_{12} &= XXXXXXXXXXXXX \\
P_{13} &= XXXXXXXXXXXXX \\
P_{14} &= XXXXXXXXXXXXX \\
%%%%%%%%%%%%%%%%%%%%%%%%%%
P_{21} &= XXXXXXXXXXXXX \\
P_{22} &= XXXXXXXXXXXXX \\
P_{23} &= XXXXXXXXXXXXX \\
P_{24} &= XXXXXXXXXXXXX \\
%%%%%%%%%%%%%%%%%%%%%%%%%%
P_{31} &= XXXXXXXXXXXXX \\
P_{32} &= XXXXXXXXXXXXX \\
P_{33} &= XXXXXXXXXXXXX \\
P_{34} &= XXXXXXXXXXXXX \\
\end{align*}

\end{document} 

As a sort of counter example, the curiosity rover on Mars uses a laser to ionise rocks to study their composition. From a practical standpoint, this looks very much like going directly from solid to plasma.

On the other hand, if you looked very closely, you'd see that the energy from the laser goes both into breaking the intermolecular and molecular bonds in the rock as well as ionising the atoms. This is in a way a necessity for generating the state generally understood by "plasma" since that implies free ions, so atoms must be both taken away from their molecules and ionised, and taking them out of molecules creates a gas, so at a low enough heating rate you go through the typical phase transitions.

CuriousOne points out, however, that the basic characteristic of a plasma - a sea of free electrons containing positive ions - is also well approximated by metals, as the valence electrons in metal crystals are not bound to individual nuclei, and some of the phenomena studied in plasmas appear in metals as well.

For OTP without a browser/Java, from the command line, you might use the snxconnect client from the snxvpn project. https://github.com/agnis-mateuss/snxvpn

The snxconnect is a script in python which tried to reverse engineer the missing bits that were dropped from the snxbinary and the web interface to use the Checkpoint VPN from Linux.

The snxconnect script is a layer on top of snx, and it says it supports OTP. Never tried it, as we do not use OTP.

The snxvpn straight installed from pip does not work. For details how to install snxconnect see this question: getting Checkpoint VPN SSL Network Extender working in the command line (hint: it is not the accepted answer)

PS. The browser does not has to be run as root, only snx (it happens by default, as it is a setuid binary). See VPN SSL Network Extender in Firefox ; but using old versions of both Firefox and Java.

As for pure snx without snxvpn/snxconnect, I am able to install and run it, however, as said, not using OTP.