"The Ring cannot be destroyed, Gimli Son of Gloin, by any craft that we here possess. The Ring was made in the fires of Mount Doom. Only there can it be un-made."- Elrond Half-Elven of Imladris
It's not a matter of heat or science. The Lord of the Rings makes it pretty clear that the one ring can only be destroyed in the fires of Mount Doom. I'm sure its got something to do with magic and what-not.
It is protected by The Dark Lord's Dark Magic. It can only be destroyed by the fires that forged it.