What Is the “Halting Problem” in the Context of Turing-Complete Blockchains?

The halting problem is a fundamental computer science concept that questions whether it is possible to determine if any given program will finish running or continue forever in an infinite loop. In Turing-complete blockchains like Ethereum, this poses a security risk, as a smart contract could be designed to run indefinitely, consuming network resources.

To mitigate this, Ethereum introduced "gas," a fee required for computation, which effectively puts a limit on a transaction's execution, preventing infinite loops from crippling the network.