Blockstream CEO Adam Back has publicly pushed back against claims that Bitcoin faces an imminent threat from quantum computing, criticizing Castle Island Ventures founding partner Nic Carter for amplifying those concerns in the open. Key Takeaways: Adam Back says Bitcoin’s quantum risk is being addressed quietly, without public alarm. Nic Carter argues the threat is real and says many developers remain in denial. The debate reflects a split over how urgent quantum computing risks are for Bitcoin. The exchange unfolded on X after Carter explained why Castle Island Ventures invested in Project Eleven, a startup focused on developing defenses against potential quantum attacks on Bitcoin and other crypto networks. Back responded sharply, accusing Carter of stirring unnecessary alarm. “You make uninformed noise and try to move the market or something. You’re not helping,” Back wrote in a post on Friday. Adam Back Says Bitcoin Developers Are Quietly Preparing for Quantum Risks Back argued that the Bitcoin ecosystem is not ignoring the long-term risks posed by quantum computing. Instead, he said developers and researchers are already working on potential protections, but prefer to do so without turning the issue into a public spectacle. In his view, the discussion has become distorted by exaggeration rather than grounded technical assessment. Carter rejected that characterization, saying a significant portion of the Bitcoin community remains unwilling to seriously confront the issue. He claimed many developers are still in “total denial” about the possibility that sufficiently powerful quantum machines could, one day, undermine Bitcoin’s cryptographic foundations. While the investment itself only recently resurfaced in online debates, Carter noted that he disclosed Castle Island’s backing of Project Eleven weeks earlier. Others are working on it, and not everyone can work on it as it's cryptography and newer algorithms. As you may know @Blockstream research has been driving and collaborating on Bitcoin related crypto like Schnorr, MuSig, Taproot etc for years. And so it is now with PQ and others — Adam Back (@adam3us) December 19, 2025 In an Oct. 20 Substack post, he said the disclosure was made upfront. “I disclosed this in the first sentence of my main article on quantum. Can’t get more transparent than that,” Carter said. Carter described himself as having been “quantum pilled” by Project Eleven CEO Alex Pruden, saying the conversations convinced him that quantum computing poses a serious, if not immediate, risk to blockchain systems. “I became extremely concerned about quantum threats to blockchains. I put capital behind my convictions, always have,” he said, adding that he expected criticism and made his financial exposure clear in advance. In laying out his case, Carter pointed to governments preparing for a post-quantum world, rising investment in quantum firms, and the idea that Bitcoin itself could act as a powerful incentive for breakthroughs in quantum technology. Bitcoin Quantum Debate Deepens as Timelines and Risks Divide Investors The debate extends beyond Back and Carter. Capriole Investments founder Charles Edwards recently warned that quantum computing could become a real threat to Bitcoin within two to nine years unless the network upgrades to quantum-resistant cryptography. Others remain skeptical. Multimillionaire investor Kevin O’Leary has argued that using quantum machines to attack Bitcoin would be a poor use of the technology, suggesting far greater value lies in fields like medical research and artificial intelligence. Back has acknowledged the importance of preparing Bitcoin to be “quantum ready,” but maintains that practical threats remain decades away, describing the technology as still “ridiculously early” and constrained by major research hurdles. The post Blockstream CEO Adam Back Slams Nic Carter Over Bitcoin Quantum Threat Claims appeared first on Cryptonews .
