Bitcoin

Quantum

Castle

Adam Back

Blockstream CEO Adam Back criticized Castle Island Ventures founding partner Nic Carter on Friday for amplifying <a href="https://yellow.com/news/vaneck-ceo-warns-bitcoin-faces-quantum-threat-as-zcash-surges-1486-on-defense-plans" rel="noopener noreferrer nofollow">quantum computing threats</a> to Bitcoin (<a href="https://yellow.com/asset/btc" rel="noopener noreferrer nofollow">BTC</a>).
The public dispute <a href="https://cointelegraph.com/news/quantum-computing-bitcoin-adam-back-nic-carter-debate" rel="noopener noreferrer nofollow">highlights</a> divisions over how urgently the cryptocurrency community should address potential quantum risks.
Back accused Carter of making "uninformed noise" after Carter explained his firm's investment in quantum defense startup Project Eleven.
<h2 id="what-happened">What Happened</h2>
Back <a href="https://cryptonews.com/news/blockstream-ceo-adam-back-slams-nic-carter-over-bitcoin-quantum-threat-claims/" rel="noopener noreferrer nofollow">responded</a> sharply on X after Carter detailed why Castle Island Ventures backed Project Eleven.
The startup focuses on developing defenses against potential quantum attacks on Bitcoin and other cryptocurrency networks.
"You make uninformed noise and try to move the market or something. You're not helping," Back wrote.
He argued the Bitcoin ecosystem is addressing quantum risks quietly without creating public alarm.
Back said developers and researchers are working on protections but prefer avoiding public spectacle.
Carter rejected that characterization.
He claimed many Bitcoin developers remain in "total denial" about quantum computing potentially undermining Bitcoin's cryptographic foundations.
Carter first <a href="https://www.coindesk.com/tech/2025/10/20/quantum-computing-is-biggest-risk-to-bitcoin-says-coin-metrics-co-founder" rel="noopener noreferrer nofollow">disclosed</a> the Project Eleven investment in an October 20 Substack post.
He described becoming "quantum pilled" by Project Eleven CEO Alex Pruden.
Read also: <a href="https://yellow.com/news/michael-saylor-predicts-bitcoin-quantum-upgrade-will-deliver-twin-benefits-hardened-security-and-identified-lost-supply" rel="noopener noreferrer nofollow">Michael Saylor Predicts Bitcoin Quantum Upgrade Will Deliver Twin Benefits: Hardened Security And Identified Lost Supply</a>
"I became extremely concerned about quantum threats to blockchains. I put capital behind my convictions," Carter said.
<h2 id="why-it-matters">Why It Matters</h2>
The debate extends beyond the two executives.
Capriole Investments founder Charles Edwards warned Thursday that quantum computing could threaten Bitcoin within two to nine years without upgrades to quantum-resistant cryptography.
Investor Kevin O'Leary argued using quantum machines to attack Bitcoin would waste the technology.
He said greater value exists in medical research and artificial intelligence.
Back acknowledged preparing Bitcoin to be "quantum ready" but maintains threats remain decades away.
He described the technology as "ridiculously early."
Carter pointed to governments planning for a post-quantum world and rising quantum firm investment.
The disagreement reflects tensions between viewing quantum computing as imminent risk versus distant concern.
Bitcoin currently trades around $87,000.
Blockstream CEO Adam Back criticized Nic Carter for amplifying quantum computing threats to Bitcoin after Castle Island invested in defense startup.
Read next: <a href="https://yellow.com/news/bitcoin-ransom-demand-targets-hyundai-group-headquarters" rel="noopener noreferrer nofollow">Bitcoin Ransom Demand Targets Hyundai Group Headquarters</a>

Bitcoin Quantum Debate Escalates Between Blockstream CEO and Castle Island VC

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Other articles published on Dec 20, 2025

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