Daniel and Kelly’s Extraordinary Universe

Can quantum measurements change the past?

Jan 20, 2026
Dive into the mind-bending world of quantum mechanics, where time may not flow as we think! Explore the intriguing idea that the past could be influenced by future events. Join the hosts as they unravel concepts of causality and the implications of entanglement. Discover the complexities of the quantum eraser and how it reshapes our understanding of retrocausality. Learn about thought experiments that challenge conventional notions, all while questioning whether we can truly alter history.
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INSIGHT

Quantum Weirdness Isn't Time Travel

  • Quantum oddities (superposition, entanglement) challenge our everyday idea of time and causality.
  • Popular headlines claiming quantum mechanics lets you change the past are incorrect and misleading.
INSIGHT

Causality Is Messier Than It Sounds

  • Causality ties causes before effects but which past events count as causes can be philosophically messy.
  • Time's apparent forward flow remains an open problem tied to entropy and deeper physics questions.
INSIGHT

Minimal Principles Use Future Boundary Data

  • Principle-of-least-action approaches (like Fermat's) determine intermediate behavior from both endpoints.
  • These alternatives use future boundary conditions but don't allow controllable retrocausation or paradoxes.
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