For anyone who asks why
Ask why, all the way down.
Type something you want to understand. You get one plain paragraph about it. The ideas it rests on are highlighted. Click one and it opens into its own paragraph, so you can start at “Ice floats” and keep asking until you reach a first principle or the edge of what anyone knows.
Nothing here is pre-written. An AI, Claude, writes every paragraph the moment you ask.
The idea
See what every explanation stands on.
Every claim rests on other claims. A textbook states one and moves on. Unfold marks the exact words its paragraph leans on, so you can open each one and check it yourself, as many layers down as it takes to reach solid ground.
How it works
Four steps to the bottom of a claim.
Ask Your Question
Type a claim or a question, including the one from a headline you've never quite trusted.
Read One Paragraph
Claude writes one explanation of about 150 words. Where the science is unsettled, the paragraph says so in plain words.
Pick a Phrase
Two to five phrases in the paragraph are highlighted. They're the ideas the explanation rests on, and each one opens.
Go One Layer Down
Click one and it opens in place as its own paragraph. Keep clicking until you reach a first principle or an open question.
Try it live
Start with whatever you've wondered about.
Type your own claim or pick one of ours. Claude, an AI model, writes each paragraph as you ask.
What do you want to understand?
Type a claim or a question, or start with one of these.
Where it stops
Every chain ends in one of two places.
Bedrock: a first principle
Some chains end at a definition or an axiom with nothing beneath it, like what “energy” means or a mathematical identity. Unfold stops there, marks it Bedrock, and doesn't invent another layer.
Frontier: an open question
Some chains end at a fact science can observe and can't yet explain. Unfold marks it Frontier and tells you plainly that nobody knows yet.
Under the hood
Three rules you can check for yourself.
Every Phrase Found
Language models miscount their own character positions, so the server ignores them and finds each phrase in the paragraph itself. repairSubclaims drops any phrase that isn't an exact match, so every phrase you can click is in the text.
One Call per Layer
Each layer is one request to claude-sonnet-5 with structured outputs, so the paragraph, its phrases and its stopping point arrive together in one JSON response of a fixed shape.
Ask Before Going Deeper
Past 8 layers, Unfold asks before it goes on. Every layer is a new call to Claude, and you hear about the cost first.
Your turn
Pick a claim. How far down will you go?
Type it in the box above. Claude writes the first paragraph in front of you, and the next layer whenever you click.