Start with the map

• Click a module to read its introduction and connections.
• Use the + in a folded module's top-right corner to reveal its concepts; use the − on an expanded module's boundary to fold it again.
• Use Search to go directly to a concept or module.
• Clear selection without changing the map arrangement.

Choose the context

• Context filters Full graph edges and, with a selection, chooses the relationships around it.
• Use named contexts such as Prerequisites, Derivation, Foundations, Uses, or Related.
• Choose one hop, two hops, or the complete transitive chain.
• Changing context does not move the graph or fold modules.

Control the surroundings

• Full graph shows every edge type named by Context; a selection colours only its reached context.
• Context only removes that background; Hidden gives details more room.
• A selected concept inside a folded module appears as a circular concept face within the module.

Move and read

• Pan and zoom freely; selection only pans enough to reveal an off-screen item.
• Fit a selected Context-only view, then use Fit++ to contract it temporarily.NEW
• Pinch or Ctrl/Cmd-wheel over details to magnify its text and graphics without changing the map.
• Preview links and inspect edges without losing the current details.
• Browser Back and Forward retrace selected concepts and modules.
• Use a block's speech-bubble +, then choose a paragraph, to add a note; a filled bubble means notes are present.

Personal layout

• Node dragging is off during ordinary browsing.
• Enable Tools → Layouts → Edit personal layout to save moved nodes locally.
• After Fit++, drag context nodes for temporary adjustments; navigating away restores them.

StudyNEW

• Practice questions reveal their answers only after an attempt or “I don't know”.
• Automatic questions are marked for you; compare free-text answers and mark yourself.
• Tools → Study tracks attempts and latest results locally, with links back to each question.
• Blue ticks record read content blocks and completed concepts or modules.
• Blue and green graph ticks summarise reading and question completion; one Study option hides both.

Personal dataNEW

• Personal layouts, notes, study-question records and blue reading ticks are stored together.
• They remain in this browser by default; authored PhysicsKG content is unaffected.
• Tools → Personal data can download or import a portable archive.
• Optionally sign in with a Google account to synchronise through Google Drive across browsers and devices.
• Privacy and Google Drive data use explains exactly what is stored and transferred.

Content status

Covers Special Relativity and General Relativity.

Manifolds and Coordinates exposition enhanced with motivating example.NEW