Model 05 · Advanced
The Difficulty Engine
How Bitcoin brings its rhythm back when mining power joins or leaves.
Explanation level
How to use this model
How to use this modelWhat you see, what you can touch, what changes, what to take away
What am I looking at?
A regulation machine of dials, gears and counters: hash-rate input, block discovery mechanism, interval clock, 2016-block epoch counter, adjustment governor, new target output.
What can I touch?
- Add mining power
- Remove mining power
- Observe expected intervals
- Accelerate simulated time
What happens when I change something?
Add mining power and blocks arrive faster at first; difficulty only changes at the next 2,016-block adjustment, which brings the average back towards ten minutes.
What should I understand afterwards?
Explain why the puzzle difficulty changes.
Understand why Bitcoin aims for about ten minutes per block.
A governor on an engine that keeps the beat steady.
After this you can
- Explain why the puzzle difficulty changes.
Add and remove mining power and watch intervals and difficulty respond.
Feedback loop you control.
After this you can
- Predict the next adjustment after a hash-rate change.
See the retarget calculation, its bounds and its probabilistic assumptions.
Timespan ratio, ×4 clamp, Poisson arrivals.
After this you can
- Compute a retarget including the 4× clamp and the 2015-interval measurement.
Open the model in its own window · works offline once loaded
Missions operate the model to complete them
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Predict the next adjustment
IntermediateCompletedPredict and then observe what happens to difficulty when mining power grows.
Your task: Predict first. Then add mining power, run the 2,016-block period to its end and trigger the adjustment.
Use: Add mining power · Accelerate simulated time · Advance through a 2016-block period · Trigger an adjustment
Difficulty does not react when hash rate changes; it waits for the end of the 2,016-block period, then scales by expected ÷ actual time (within ×¼ to ×4). Until then, blocks simply come faster.
Missions are checked from the model's own simulation state, not from clicks. No time limit. Completion is stored only in this browser. The quiz questions in the learning paths remain available.
Tutor Ask a question, or let the tutor show you around
The tutor answers by explaining and, within the permissions below, by operating this model. Every change it makes is shown and listed, and you can undo it. It cannot run code, read your browser data or see anything secret. The page works the same without it.
What the tutor did
Common mix-ups
- Myth: Difficulty changes continuously.
- In fact: On mainnet it changes only at 2016-block boundaries.
- Myth: Blocks arrive every ten minutes.
- In fact: Ten minutes is the expected average; observed intervals are random and widely spread.
Concepts in this model
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