So absent something enforcing prohibition of defection from a collective action, the collective action doesn't happen.

You want to actually solve the problem? Find such an enforcement mechanism (CO2 tariffs, perhaps), reduce the cost of solution (sufficiently cheap non-fossil energy), or find another solution that doesn't require global cooperation (albedo modification, say).

A solution that just requires everyone to get along and cooperate to their marginal net detriment doesn't seem like it will work.

It's quite an event with long lines to get in and is loved by all. The money raised is used to buy more books for the library.

https://booksale.org/

In that case, the anti-AI Luddite arguments are maximally impeached, since they are motivated by fear of personal disaster. Tao doesn't need AI to succeed; the Luddites desperately need it to fail. So they are willing to say anything, jumping right to ad hominem arguments when they lack any real substantive rebuttal.

I remember this when anyone complains large scale use of solar and wind would be expensive. So is large scale use of any energy source.

BTW, I don't think largeness is needed for photodisintegration to occur; this should happen even in garden variety type-II SN.

It's a tremendously economical way to test compilers. For a modest and finite investment in testing infrastructure I get an unlimited number of tests. Over the years I've run many billions of test inputs on various Common Lisp implementations, although I'm mostly focusing on sbcl these days. When a bug is found the input quickly reduces to a something small that usually immediately tells the developers where the problem is (usually but not always something introduced recently.)

I also have a testing harness that cobbles together usually erroneous Lisp code and sees if the compiler blows up (the sbcl compiler as designed must never throw an error condition even on erroneous input.) This exploits a corpus of public Common Lisp code, combining and mutating the code in various ways.

For a normal, non-relativistic gas in which the particles have no internal degrees of freedom, gamma is 5/3. As a gas becomes more relativistic, and as photon pressure becomes more important, gamma declines toward 4/3.

For gamma = 4/3, a self-gravitating gas will be marginally stable: the energy needed to compress a sphere of the gas will be equal to the gravitational potential energy liberated by the compression. So, any effect that pushes gamma below 4/3 makes it unstable against collapse.

In a conventional core collapse SN this is photodissociation of nuclei, where energy gets soaked up in breaking apart nuclei into alpha particles and then free nucleons. In a pair-instability SN, this is increasing conversion of photons to electron-positron pairs.