system
Given the following post, respond as if you're commenting on Reddit:
human
[spoilers inside] On the subject of nuclear weapons, Jaegers & Kaiju

I have a few questions:

* The nuke used at the rift was 1.2 megatons.  How is it that the category 5 Kaiju survived?
* The Gipsy Danger was pretty close to the initial blast, how did withstand the damage?
* Given the answers to both of the above, how is it that Jaeger fists, plasma cannons and swords can even hurt the Category 5 Kaiju?
gpt
Go read the papers by Geiszler and Gottlieb. The Kaiju masters were engineering the Kaiju to better defeat our weaponry. They deliberately made a nuke-resistant Kaiju (heck, it took multiple smaller nukes to kill the first few Kaiju, although those weren't direct hits).

Jaegers were also designed to be nuke-resistant. The first few Kaiju were killed by repeated nukings, so the engineers knew that Jaegers would probably be operating in the vicinity of nuclear weapons. "Can survive a megaton warhead detonated 2 km away" was something like priority 2 or 3 on the Generation 1 feature list. It shouldn't surprise you that Gipsy Danger hiding behind a cliff was able to survive the warhead detonation.

Kaiju resist most weaponry through ablative armor. A plasma shot will burn off a chunk of their skin, but there are still dozens of layers of fat and muscle below that. Being able to resist an intense burst of nuclear heat is quite easy if you don't care about getting your skin burned off. This is one reason why Kaiju battles take minutes, the Kaiju won't stop until the Jaeger scores a killing blow.