Metric Space

• Hilbert Space — from Wolfram MathWorld
• Hilbert space — Britannica
• Complete Metric Space — from Wolfram MathWorld
• Cauchy Sequence — from Wolfram MathWorld
• Banach Space — from Wolfram MathWorld

QK-4d

• Meet The Four-Dimensional Numbers That Led to Modern Algebra | WIRED
• Imaginary Numbers
• Visualizing quaternions (4d numbers) with stereographic projection - YouTube
• Something Deeply Hidden | Sean Carroll | Talks at Google - YouTube

QK-Mathematical Philosophy

• Introduction to Mathematical Philosophy

• How Wittgenstein might ‘solve’ both philosophy and quantum physics | Aeon Essays

• What Einstein meant by ‘God does not play dice’ | Aeon Ideas

• A Private View of Quantum Reality | Quanta Magazine

  QK-Atoms

• Identical particles - Wikipedia

• Bose–Einstein condensate - Wikipedia

• Atom - Wikipedia

• Wick rotation - Wikipedia

• Minkowski space - Wikipedia

• Position and momentum spaces - Wikipedia