Hi everyone,
Let's imagine that few days ago new altcoin appeared. It's, for example, scrypt based. And total hashrate is, at example, 5 GH/s. If I have 10 GH/s scrypt miner, how that will affect on that new altcoin? I will own 66% of hashing power, right? I will able to do 50% + 1 attack, right?
Depends on a lot. Mainly how the diff is figured. We often attack coins new and old with a low diff and scrypt or another easy algo. You are guaranteed a good block, at least that one, but after that the diff is going to start changing to meet your work. This is especially true if you are solving the blocks. The difference is there to make a block get solved every X minutes.