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Slots, epochs and the beacon chain

The consensus clock of QRL 2.0 — what slots and epochs are, and what the beacon chain does.

5 min readUpdated 2026-06-20

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QRL 2.0's Proof-of-Stake runs to a strict clock kept by the beacon chain. Two units define that clock: slots and epochs. Getting them straight makes validator and consensus data on this explorer far easier to read.

Slots: the 60-second heartbeat

Time on QRL 2.0 is chopped into slots of 60 seconds. In each slot:

  • exactly one validator is chosen to propose a block, and
  • a committee of validators attests (votes) on what they see.

If the chosen proposer is offline or misses its turn, the slot can simply be empty — there's no block for that slot. That's normal, especially on a quiet test network, and it's why block heights and slot numbers aren't always one-to-one.

Epochs: 128 slots at a time

Slots are grouped into epochs of 128 slots. At 60 seconds per slot, that's:

128 slots × 60 seconds = 7,680 seconds ≈ 2.1 hours per epoch

Epochs are the bookkeeping unit of Proof-of-Stake. At epoch boundaries the protocol:

  • assigns validator duties for the coming period,
  • tallies attestations, and
  • advances finality — the point at which past blocks become effectively irreversible.

A note for the technically curious: QRL 2.0's epoch length (128 slots) and slot time (60 seconds) differ from Ethereum's (32 slots × 12 seconds ≈ 6.4 minutes). So a QRL 2.0 epoch is roughly two hours, not a few minutes. Don't assume Ethereum's numbers carry over.

What the beacon chain does

The beacon chain is the consensus layer that runs this clock. On QRL 2.0 it's operated by the qrysm client (a fork of Ethereum's Prysm). Its responsibilities:

  • maintain the validator registry — who's active, their stake, their keys,
  • schedule which validator proposes and which committees attest each slot,
  • process attestations and drive finality, and
  • record validator-affecting events like slashings.

The beacon chain works alongside the gqrl execution layer, which handles the actual transactions and balances. Consensus on one side, execution on the other.

Seeing it on the explorer

Quantascan indexes the beacon chain directly, so you can browse beacon blocks, the validators registry, and epochs. When you see a slot with no block, that's an empty slot — expected behaviour, not an error.

Where to go next

FAQ about Slots, epochs and the beacon chain

Common questions about this page
How long is a slot on QRL 2.0?
A slot is 60 seconds. In each slot, one validator is selected to propose a block. Some slots can be empty if the chosen proposer is offline.
How long is an epoch on QRL 2.0?
An epoch is 128 slots, which at 60 seconds per slot is about 2.1 hours. Epochs are the unit the protocol uses to assign validator duties and account for finality.
What is the beacon chain?
The beacon chain is QRL 2.0's consensus layer, run by the qrysm client. It keeps the validator registry, schedules who proposes and attests each slot, and finalises the chain epoch by epoch.