The order of the blocks in blockchain does not really mean that that is the same order the transactions were done. This is a major problem with blockchain and Qurrex looks forward to solving it. When you initiate a transaction, it will go to a pool that is not confirmed. The transactions are added to the blockchain after confirmation and validation. This can lead to the following complications:
Double spending
If you use the same transaction reference then you risk creating more than two transactions. The transactions would then go to a pool that is unconfirmed. It can then be minded by another miner and be added to different blocks.
Speculations
If there is no order in carrying out transactions, there could be different branches of the block and numerous miners will mine transactions and put them on the block in parallel. This will lead to speculations as to which of the chains is the right one.
The solution
Each block on the blockchain carries a mathematical puzzle. The puzzle should be solved in order for transactions to be added to the block. Adding transactions to the block lead to the chain growing. Cryptography is used to solve this puzzle.
A block constitutes of previous block reference, unique identifier to the block, a list of transactions and random guess or a nonce.
SHA256 is a cryptographic function used on the Bitcoin blockchain. The function takes the input as characters then converts it to a 32bit value. This function is very complex and even one punctuation mistake can lead to a completely wrong digest value.
Miners keep on guessing the nonce so that they get an output within a particular target. A target value is typically fixed in that the average time used to solve is not more than 10 minutes. It is important to note that the computing power keeps increasing and the target values also change accordingly. This makes sure that solving is complex but yet possible.
After identifying the result, it is the unique identifier to the block. We can also call it the fingerprint. It is difficult to solve the puzzle and this makes the probability that a different miner solving it at the same time is rare. Even if this happens then you should know that there are different branches of the blockchain and one branch is built on top thus growing the branches.
If this happens and we get a tie, the tie can be resolved after mining the second block. Adding the second block to path 1 makes itto be confirmed link and the path 2 transactions go back to the unconfirmed pool. People trust the longest network on blockchain thus whenever a block is added, you need to wait for 10 minutes for it to be safe because the transactions went to unconfirmed list. This can also lead to double spending because the transactions are not confirmed. Qurrex will address these issues on their platform and reduce the problem of double spending.
Website https://qurrex.com/
white paper https://drive.google.com/file/d/1klzZPHdjCBnurHCJjJbjwsed_5rx4W1U/view