okay, so the United States has a nuclear arsenal that can conceivabley blow up the world. BUT is there one single bomb that can do the trick? a couple? or would it have to be a country-by-country assault? could they actually make the planet explode from the inside, or just destroy the surface? this is ignoring the possibility of a nuclear winter wiping out crops and freezing us all to death. just bombs, please.
If you mean actually blowing up the world, as in physically destroying the planet, no…the entire arsenal of nuclear weapons that exists or ever has existed on Earth is not enough to do that.
The largest nuclear device ever tested was a 57 megaton composite bomb detonated by the soviets. The actual design yield of the weapon was 100 megatons, but an inhibitor was incorporated to keep the explosion clean for test purposes. This test was performed purely to demonstrate their capabilities - the device was never weaponized, although there were later unsubstantiated claims of even larger devices.
Practically, there is no military application for a weapon of that yield. The only possible proposed use would be wide area sterilization of threatening biological agents (a long incubation time, airborne strain of Ebola, for example), but in that case the risk of doing nothing would have to outweigh the risk of aftereffects of the nuclear explosion.
The rest of your question is just silly.
You mean like a Death Star kind of thing?
The asteroid that killed the dinosaurs was much more powerful than the world’s entire weapons arsenal and we’re still here. Even a planet the size of Mars crashing into Earth wouldn’t completely destroy it (it would certainly destroy all life on it, obviously).
We were not here when the dinosaurs were killed off by a asteroid, or comet or whatever.
I believe the combined nuclear arsenal falls short in terms of total energy to a very active volcano eruption or a tornado.
Don’t believe that is possible. Extremophiles can survive pretty harsh conditions. I read somewhere that they found bacteria in nuclear spent rods, deep in arctic ice, and in the upper atmosphere. All sterilization techniques also do not claim 100% bacterial removal.
So yeah, maybe all life forms above a certain size maybe wiped out - but life as such would still survive.
“It’s life, Jim, but not as we know it.”
How would you test such a device? Suppose the government said they had a bomb capable of that-so what, it’s just an assertion until they launch the sucker.
Here are some numbers to illustrate.
A Hiroshima size nuke releases something in the range of 10^14 J. The energy needed to overcome the gravitational attraction of the Earth, causing it to disperse and not reform is somewhere in the range of 10^33 J. The energy needed to make it pop explosively ala Death Star is in roughly 10^38. To blow up Earth you need around 10 quintillion Hiroshima sized bombs. To make it pop ala Death Star you need 100,000 times that.
At no point have all the combined arsenals of all nuclear powers come close to being able of covering the world in fireballs, let alone cracking it. At worst we could kill off a significant portion of humanity. But we have never been capable of killing all of humanity, let alone all life.