Bitcoin
Bitcoin (BTC) is the original and largest cryptocurrency by market capitalisation, launched in 2009 by the pseudonymous Satoshi Nakamoto. It introduced the blockchain as a trustless, decentralised payment ledger and inspired thousands of successor cryptocurrencies.
Technical Overview
- Ledger type: Proof-of-work blockchain
- Supply cap: 21 million BTC (programmatic; ~18.5 million mined as of 2021)
- Transaction time: ~10 minutes per confirmation
- Transaction fee: ~$20 average (as of 2021, prasad-2021-five-myths-cryptocurrency)
- Cryptographic security: ECDLP-256 for wallet signatures
Dominant but Flawed as Currency
prasad-2021-five-myths-cryptocurrency argues Bitcoin largely fails as practical money:
- Slow and expensive transactions preclude everyday payments.
- Price volatility is extreme (multi-day swings of 30%+ are routine).
- Tesla accepted then reversed Bitcoin payments within months.
Despite this, Bitcoin retains ~50% of total crypto market cap — the “granddaddy” that remains dominant even as newer coins offer faster speeds, lower fees, and greater anonymity.
Speculative Asset Profile
- Supply scarcity (21M cap) is frequently cited as a store-of-value argument, analogous to gold.
- However, scarcity alone doesn’t create value — demand can evaporate if belief in the asset collapses (prasad-2021-five-myths-cryptocurrency).
- Bitcoin is the leading asset used in crypto investment scams, including pig butchering and money-mule laundering schemes.
The Quantum Threat
Bitcoin’s security rests on ECDLP-256. A future quantum computer running Shor’s algorithm could derive a wallet’s private key from its public key, enabling theft of any coin whose address has been exposed.
Key estimates:
- babbush-neven-2026-quantum-vulnerabilities-cryptocurrency (Google, 2026): ~500,000 physical qubits required.
- Combined Google + Caltech estimates (cottier-2026-quantum-computing-breakthroughs): As few as 25,000–30,000 qubits — down from millions just one year ago.
scott-aaronson describes this as a strong incentive to upgrade to quantum-resistant encryption.
Google’s recommendation: Avoid exposing or reusing wallet addresses; transition to PQC blockchains.
Related Pages
- cryptocurrency, blockchain, elliptic-curve-cryptography, post-quantum-cryptography, shors-algorithm, quantum-computing