"F*ck you, space! Being all spacey and stuff!" (At least that's what it sounds like in my imagination.)
"During the Trinity test, Enrico Fermi recalled Teller's idea of igniting the atmosphere. In an attempt to relieve some tension, he started taking bets on whether the test would destroy the world, or merely glass the State of New Mexico."
from: https://www.metabunk.org/debunked-scientists-risked-destroyi...
And it still doesn't really make a difference, on the grand scale of things.
Space would probably just go "That's cute" ..if it even noticed it.
Space is used to vastly more stronger forces – the kinds that create planets and destroy stars. Heck, there's probably more energy being flung around in Jupiter's storms every day if not every hour, than we could ever produce on Earth.
We could literally blow our planet apart (though even that may be nigh impossible) and it still wouldn't make much of a difference to our own solar system, let alone the galaxy around it.
I think we would be a happier species if we accepted our insignificance and tried to make the best of our infinitesimal corner in time and space, rather than having delusions of grandeur, trying to one-up and cower fellow insignificants with insignificant acts..
Which, you know, kinda makes me giggle a little. We, the US, attacked space with a hydrogen bomb. The scientific world wasn't actually sure what effects this would have and we're like, "Hold my beer and watch this."
And then, we bombed space. That might actually be one of the most American things we've ever done.