Model 03 · Bitcoin Fundamentals
The Chain of Blocks
Why changing the past breaks everything after it.
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 horizontal chain of precision block containers joined by illuminated cryptographic linkages; each block opens to reveal its header, Merkle tree and transactions.
What can I touch?
- Open and close blocks
- Inspect transactions
- Expand a Merkle tree
- Modify demonstration transaction data
What happens when I change something?
Edit one transaction and its block's Merkle root and hash change, the proof of work no longer meets the target, and every later block's link to it breaks.
What should I understand afterwards?
Explain why changing an old block invalidates the blocks after it.
Understand why blocks are linked.
Wax seals that each include the previous seal.
After this you can
- Explain why changing an old block invalidates the blocks after it.
Change a transaction and watch the seals break down the chain.
Tamper and observe.
After this you can
- Show how editing one transaction changes the Merkle root and breaks proof of work.
Explore hashing, Merkle trees, headers and cumulative chainwork.
Header fields, Merkle paths, work sums.
After this you can
- Compare two branches by cumulative work rather than length.
Open the model in its own window · works offline once loaded
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.
