Blockchains are mostly timestamp machines
Proving time is hard, and worth trillions.
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This article is inspired by talks with a cryptographer friend who keeps trying to think of blockchain-less designs that offer the same advantages as blockchains. Hi Jonas 👋
I’m a fan of blockchains, but also wrote Blockchains are Mostly Useless. In that little book I cover what characteristics blockchains offer, and when it is useful (rarely). What the aforementioned Jonas keeps pointing out is that there are alternative cryptographic tools to do most things that blockchains do.
If I may summarise my friends’ positions:
Ledgers - a blockchain is a ledger, but so is an Excel spreadsheet
Immutable - blockchains are append-only and do not rewrite history. Centralised databases can do this too.
Distributed - the distributed nature of blockchains is cool, but there are plenty of non-blockchain distributed systems
Permissionless - blockchains allow anyone to access them under the same rules, no privileged access. This is in many ways possible without blockchains.
Trustless - blockchains remove the need to trust an authority at their word.
To be clear, I think blockchains are a beautiful cocktail of the things above. But in theory there are other ways to do those things. I think they would suck. But that is not the point of this post.
Can I prove I’m in Amsterdam?
If I upload a picture of me in Amsterdam to instagram today, with the intention to prove I am here, what guarantees to you have?
You know I claim I took the picture today
You know I claim to post the picture today
You know Instagram claims I posted the picture today
On the current Instagram I do not cryptographically claim (ie sign a message) the above, and neither does Instagram.
But what if we did? What if we both signed with our cryptographic keys/wallets that we claim the above?
You know for sure that:
I claim that I took the picture and posted it today
Instagram claims to have posted the picture today
You are 100% certain that I and Insta claimed this (assuming our keys are not compromised).
What do you not know for sure:
You do NOT know my claim is true
You do NOT know Instas claim is true
Proving time is a relative thing
Think about any case where we want to claim something happened at a certain point in spacetime.
Movies using newspapers as proof they are in the future
Crime witnesses testifying that they saw something happen
Video evidence that something happened
All of these are circumstantial evidence, because fundamentally we cannot prove anything about the past. We can only look at the state of the present.
Even claims about the past with sophisticated methods like carbon dating are really just claims about the present, combined with a theory of what that means in the past.
The trustworthiness of claims about the past increases with the amount and randomness of the data points we are using.
Did 1 cellphone video show a UFO above NYC? Probably just a cloud with weird lighting
Did 10 cellphones see the same? Interesting news story, but probably the same cloud
Did 1000 cellphones, 50 satellites, and 5 F16 sensors see it? Ok fine the invaders are here.
The reason the spread and randomness is considered “proof” is for 2 reasons:
Different points of view - ie in the example of a single cellphone it might just be the angle of the phone relative to the sun that makes it do something weird
The incentives - the cellphone user might want to get TikTok famous and might lie or exaggerate. But the camera on the ATM machine on the corner? They don’t have that incentive.
While not always true, the accuracy of claims about time increases the more disparate data points you collect.
Blockchains are a spread out consensus machine
The nature of blockchains means that every claim about the current state of the blockchain can only be coherent is the past was not tampered with.
It’s like a domino or butterfly effect. Trying to change even a small thing in a blockchain entry a year ago would require rewriting the entire blockchain from that point.
So what if you put a time claim on a blockchain?
What if me and Instagram post the fingerprint and claims of my picture on a blockchain? You would know for sure that when you see that proof:
I claimed to have taken and posted the picture on that day
Insta will claim to have posted that picture on that day
EVERYONE using that blockchain corroborates our claims
Who is everyone using that blockchain and what are their incentives?
Financial applications, for example those managing $245,613,892,557 of stable coins at the time of writing1
People trading useless meme tokens, which is silly but a few billion dollars nonetheless
Validators/miners with billions at stake when they lie
What is the worst the people running validation or RPC nodes can do?
They can try to rewrite history - And you would be able to very cheaply prove that their claim on my or Instagrams behalf is a lie (because of the way the cryptography works)
They could erase the claim from history - But it would take only one copy of the true original history to prove that my claims about the past are coherent
Imagine how many people and organisations I would have to coerce into trying to rewrite history. Imagine the time and money required. That is the protection you have against lies on a blockchain. In theory you can tamper with them if you get the whole world with all of its incentives to go along. But you most likely won’t be able to.
The timestamp machine is amazing
So there you have it. Blockchains are timestamp machines.
Why does that matter?
Because the coherence of the important things in life depend on claims and when they are made.
Ask yourself:
What proof do you have of your bank balance? If you had to dispute a fraudulent bank? What if they show a printed balance overview from last week that shows 0, and yours at home shows more? What do you claim? You claim yours came first.
What proof do you have that you own the lease or title to your house? What if someone makes a fake contract showing they own the house? Will you claim truth based on the color of the paper? No, you claim your documentation is older.
Two van Gogh paintings are offered for sale. One is a fake. One is real. What do you try to figure out about them? The first thing is probably their age. The only question is how.
Timestamps matter.
💡 Remember you can get free copies of my books here.