Is a 51% attack currently viable?

[johnny5johnny5]

The biggest threat is a world government using its vast resources to go after a cryptocurrency blockchain is it not?

[ViceOfBTC21]

Large companies such as Google has enough money to execute 51% attack. So yes, it's viable but it isn't worth the risk of Bitcoin devaluation.

[ownageplocks]

As with anything that has to do with bitcoin, it's an open market which means it will sort itself out(even if this means a 51% attack). Bitcoin is not going away no matter what any amount of miners do(unless they all stop).

[respid]

So why the developers don't take any measures to mitigate this risk?
Is there any at all?

[stompix]

I'm more terrified about an attack made with 20% or 10%  hash rate that would involve empty or half empty blocks.

Even a 10% drop in the network capacity to rely transaction would really spike the fees beyond 800 and maybe 1000 satoshi/b.
And that would be pretty damn bad.
Especially right now as we see hashrate going away and we will have till the next difficulty even slower blocks.

[Razick]

Sure, it is always possible. Anyone or any organization that controls over half of the hashing power essentially controls Bitcoin. They can re-write transactions, and do whatever they please. And technically it isn't illegal, or it shouldn't be given it is something everyone already knows, an open flaw in the system if you will, and it is free to be exploited.

[drachman]

At the present, does any one company have the capabilities to do it?

That kind of attack is always a possibility, right now no one can perform such an attack but as long as bitcoin exists the 51% attack is going to be a very dreadful possibility.