Playground 07
Observer-Dependent Particle Content
Compare an inertial observer and an accelerated observer on a spacetime diagram, then see how the same field state can look thermal in Rindler coordinates.
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Current build step
1. Minkowski observer in the vacuum
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gentleclearstrong
quietresponsivehot
subtlevisiblestrong
Minkowski
vacuum
Unruh temp
cold
Rindler view
forming
Spacetime Comparison
Minkowski versus Rindler description
The inertial observer sees the vacuum. The accelerated observer is confined to a wedge and can interpret the same state as thermal.
Spacetime diagram
Thermal response
An accelerated detector can click as if it is immersed in a bath. The temperature grows with acceleration.
Unruh relation
Detector reading
0.04
Thermal spectrum sketch
Interpretation comparison
Nothing about the global quantum state changed. What changed is which modes the observer naturally uses to describe the field.
Inertial view
vacuum, no particles
Accelerated view
thermal quanta
Key idea
What to notice
The strange part is not that the vacuum changed. The strange part is that different observers decompose the same field into modes in different ways.
Why it matters
This is one of the clearest examples that “particle” is not absolute in quantum field theory. It depends on the observer and the mode basis they use.
Try this
Increase acceleration and detector sensitivity together. You should see the thermal panel wake up while the inertial interpretation still stays labeled as vacuum.