The Myth of 51%
For years, the crypto industry has repeated one mantra:
“You need 51% of the hashrate to reorganize blocks and compromise a Proof of Work (PoW) chain.”
But Qubic just proved that this isn’t the whole truth. With only 28% of Monero’s hashrate, Qubic managed to reorganize the chain—showing that PoW may be far more fragile than anyone expected.
The Reorg That Changed the Conversation
At first, media headlines screamed about Qubic “controlling 51%.” But the actual numbers told another story: their real share was closer to 28%.
And yet, with less than one-third of the hashrate, Qubic still achieved a 9-block reorg.
As Come-from-Beyond (CFB) put it:
“Doing a reorg with 28% looks much worse than doing one with 51%. It shows that PoW is much less secure than many expected.”
Inside the Monero Logs
The Monero community saw this unfold in real time. Developers confirmed that Qubic could have pushed the reorg much further.
In fact, they had the chance to reach more blocks, but decided to stop at 9.
“They only reorg’d 9 blocks… but they were at height 23 when they decided to push.”
(Excerpt from Monero Research logs)
This was a critical distinction: Qubic wasn’t out to destroy Monero—it was testing the limits of Proof of Work.
A Test, Not an Attack
This nuance is vital. Qubic never crossed the 10-block confirmation line that exchanges require to prevent double spends.
Monero developers later confirmed Qubic had the capacity to push up to 15 blocks, but the reorg was deliberately stopped at 9.
Instead of chaos, this restraint turned the event into something more valuable: a proof-of-concept stress test for the entire Proof of Work model.
The Lesson Nobody Wanted
What the test revealed is uncomfortable:
- PoW is not only about percentages. Even sub-50% hashrate can destabilize a chain.
- Block distribution matters. Qubic showed that controlling blocks, not just raw power, can bend consensus.
- The industry’s assumptions need to be re-examined. The 51% rule was never the full picture.
Redefining Security
Qubic didn’t kill Monero. It revealed a blind spot in how we think about security.
The experiment demonstrated that PoW’s strength isn’t guaranteed by a magic number—it depends on deeper dynamics like block propagation, pool concentration, and miner incentives.
- The takeaway: a 28% reorg is more terrifying than a “classic” 51% attack.
- The implication: crypto must rethink how it defines “secure.”
Qubic didn’t invent a new PoW — it broke the myth around it. The idea that only 51% matters is no longer true. The reorg proved that even with less, the system bends.
