

You cannot encrypt email End to End.
Incorrect.
https://support.mozilla.org/en-US/kb/introduction-to-e2e-encryption
It has to be stored in plaintext somewhere.
- It doesn’t.
- Even if it did, that wouldn’t mean it wasn’t E2EE.
Yahoo does not offer encrypted email.
It doesn’t need to. https://support.mozilla.org/en-US/kb/thunderbird-and-yahoo
I don’t know how you would measure gravitational waves without measuring gravitational attraction.
Nobody said it was. The “speed of light” isn’t about “light”. Gravity propagates at the same speed, aka “c.”
This Reddit discussion on r/AskPhysics might help clear up your misconceptions. Notably:
I get the sense that you’re thinking about the second scenario when objecting to the concept that gravity travels at the speed of light.