Ledger LandISSUE #10 of 90

proof of work · mining · difficulty

BlockyVSDouble-Spend Dan

Blocky saysProof of Work secures a chain by making miners spend real computation to add blocks.

In PoW (Bitcoin), miners race to find a number (nonce) that makes the block's hash fall below a target — pure trial and error costing electricity. The winner adds the block and earns a reward. Cheating means out-computing the entire honest network (a 51% attack), which is prohibitively expensive. Security comes from burned energy; the trade-off is high energy use.

Power-ups you unlock

Miners brute-force a hash below a target
Winner adds the block, earns the reward
Attacking needs >50% of total compute
Secure but energy-intensive

Double-Spend Dan attacks — common mistakes

Thinking mining "solves math problems" usefully
Underestimating 51%-attack cost on big chains
Ignoring PoW’s energy footprint

Boss battleExplain why a 51% attack on Bitcoin is economically irrational.

Example code

<!doctype html><html><head><meta charset="utf-8"></head>
<body style="background:#06040d;color:#e6e0ff;font-family:monospace;padding:20px"><pre>find nonce so hash(block) &lt; target
→ trial & error, costs electricity
→ winner adds block + reward
cheat = out-compute everyone (too costly)</pre></body></html>

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