Ethereum - The Scalability Imperative

What is the blockchain trilemma?

The blockchain trilemma states that a blockchain can optimize only two of the following three properties at the same time:

1⃣ Decentralization
2⃣ Security
3⃣ Scalability

Improving one often weakens another.

Who introduced it?

Vitalik Buterin in 2017.

What is security in blockchain?

The ability to protect the network from:

• Attacks

• Fraud

• Double-spending

• Data manipulation

Why is security expensive?

Because strong security requires:

• Distributed validation

• Complex consensus

• High computational costs

These reduce speed.

What is scalability?

The ability to handle:

• Large transaction volumes

• High throughput

• Fast confirmations

Why is scalability hard?

Because increasing speed usually means:

• Fewer validators

• Bigger blocks

• Less distributed control

Which reduces decentralization or security.

Why can’t a blockchain optimize all three?

Because:

More decentralization → slower consensus
More security → heavier validation
More scalability → fewer nodes or shortcuts

Each improvement adds trade-offs.

What was Ethereum’s biggest weakness in the blockchain trilemma?

Scalability was the most compromised.

Why couldn’t Ethereum easily process many transactions?

Because it prioritised decentralisation and security, which limited scalability.

How did the gas limit affect transaction speed?

It limited Ethereum to about 20 transactions per second (TPS).

Why is 20 TPS a bottleneck?

Demand was much higher than capacity, so transactions piled up.

Why did Ethereum fees surge during busy periods?

Because users competed by paying higher gas fees to get priority.

How did miners/validators choose which transactions to process first?

They prioritised transactions with higher fees.

Did paying more always make transactions faster?

No — speeds stayed relatively fixed due to block limits.