Bitcoin Blockchain - Verification process

Question

As the title states, basically my question is about the blockchain verification. I know whats a block chain and basically understood how mining is working, except once simple thing.

Let's say we have 2 guys, Bob and Adam.

Blockchain:

    |1|-|2|-|3|-{4}   - Bob Chain
    |1|-|2|-|3|-{4}   - Adam Chain

Assume both Bob and Adam found a new block, but it will not be verified until someone finds a next block. So my questions is whats is happening in a situation if Adam will find a block |5| first. Will Bob get his reward for finding a block? Or it means if Adam found one block, he has to find the next one which is extremely difficult without a huge network of computational resources in order to verify his previous block |4| and get reward for block 4 of 12.5 bitcoins, because the nodes will only accept the longest blockchain? I hope I clearly illustrated the picture. I've tried to find the answer in different videos and materials but somehow this aspect was put aside. If my assumption is true, it means there is no way how can a single person to earn anything from mining without a huge network ?

Answer 1

Assume both Bob and Adam found a new block, but it will not be verified until someone finds a next block. So my questions is whats is happening in a situation if Adam will find a block |5| first. Will Bob get his reward for finding a block?

No. If Adam finds block |5| first and it is a valid block, Adam will quickly broadcast this to the bitcoin network and the proliferation of said block will take place very quickly across the entire bitcoin network. Nodes that receive Adam's block 5 will also start to orphan Bob's block 4 since Adam's block 5 is now the tip of the longest, valid chain. Other miners will also quickly switch to mine on this block tip to avoid mining on an orphaned block.

Or it means if Adam found one block, he has to find the next one which is extremely difficult without a huge network of computational resources in order to verify his previous block |4| and get reward for block 4 of 12.5 bitcoins, because the nodes will only accept the longest blockchain?

Not necessarily. Once Adam's block (i.e. block 5) is broadcasted, another miner might be lucky and they could extend block 5 to block 6. Adam's block will remain as part of the canonical chain.

If my assumption is true, it means there is no way how can a single person to earn anything from mining without a huge network ?

More or less true. Your chances of finding a block is based on your hash rate proportional to the network hash rate. Under today's conditions, the probability of a solo miner finding a bitcoin block is very small, but still a remote possibility. Therefore, we have mining pools in bitcoin.