Physicists have been discussing spacetime since the early 1900's. A very smart person, by the name of Albert Einstein, modeled space as 4 dimensions rather than just 3. The axis were then X, Y, Z and .... time.

Fortunately, you don't need to understand Relativity Theory in order to grasp Proof of Spacetime!

## PoST

Fast forward 100 years or so and two researchers, Ilan Orlov and Tal Moran, proposed a new consensus mechanism where users staked space in their storage systems as a proof of value.

If you think this sounds a lot like Proof of Capacity (or Proof of Space), you wouldn't be entirely wrong.

PoST is very similar to other consensus mechanisms where storage space is used as a stake in the mining process.

But, as you may have noticed, Pos**T** adds one additional ingredient to Proof of Space : **T**ime!

## Ticking away, the moments that make a up a dull day!

In a Proof of Spacetime system, the amount of time the space is used in your local storage adds to the value you can prove to the network.

For example, whereas in a pure Proof of Space you would prove 3 terabytes of storage, in a PoST system you could prove 3 terabytes-month. That'd mean you proved that 3 TB of storage was allocated to the network for a month.

PoST guarantees that a certain resource was locked for an amount of time. This adds another guarantee that stakers won't just allocate space until a block is minted and then turn their machines off for the rest of the month, for example.

Spacemesh uses a blockmesh (instead of blockchain), which deploys PoST for its consensus mechanism.

## Links

Return to main article: **ELI5 Summary of cryptocurrency consensus mechanisms**

Spacemesh Proof of Space-Time

Startup Raises $3 Million to Build 'Proof-of-Space-Time' Blockchains

Simple Proofs of Space-Time and Rational Proofs of Storage

What Sets us Apart: Filecoinâ€™s Proof System