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Comment by bobm_kite9 | Hacker News Reader

What about the 51% attack problem? Why doesn’t this matter? Can someone explain how this currency is a good bet when there is this seemly huge gaping hole in the system. Honest question!

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If I understand correctly, at the moment if someone would want to do the 51% attack, they would need to spend energy for proof of work that would overpower the rest of btc the network, which is equal to expenditure of Argentina in kWh. A lot of people complain about this expenditure.

If you have enough hash power to 51% attack Bitcoin at all, your potential for rewards by instead mining honestly are significantly higher, at least that's how the game theory generally plays out

The other aspect is that, as someone approaches 51%, there is increased incentive for everyone else to prevent that from happening.

Bitcoins of mass destruction. Going to war over BTC control sounds absurd. But so does $50k a pop. So who knows.

It would be extremely costly and if you were to already invest all that money, your incentive is to make money from it, not cause a very short term disruption.

At current energy prices, assuming you need half of the energy needed to do mining to perform a 51% attack and you have access to the needed hardware. You need to burn ~12 million usd daily to take over the network

It's a huge problem.

Worse, bitcoin's massive electricity usage results in data center consolidation.

If a nation state just simply wanted to impair bitcoin, they could chop off electricity to a few warehouses. If they cut off 25% of miners, blocks would take 25% longer, and difficulty retargeting would take about three weeks. At 50%, blocks take twice as long and retargeting would take a month.

Worse, there's the "time travel attack". Say a nation state quietly amassed 51% of mining power. They could quietly mine blocks and release them all at once, reversing transactions for however long they were mining. This is not a double spend mind you, just simply release empty blocks. Mined for 2 weeks? Reverse 2 weeks of transactions. Then rinse and repeat.

that's right i wonder the same. a motivated state actor with access to hydroelectric dams, nuclear power and large datacentres can still easily take over the network.

> can still easily take over the network

How much compute power and electric would that take?

How many miners are in China?

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