Quantum Field Theory In Curved Spacetime - Department of Physics at UF

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Quantum Field Theory In Curved Spacetime José Roberto Vidal Universidad Autónoma de Madrid

Transcript of Quantum Field Theory In Curved Spacetime - Department of Physics at UF

Page 1: Quantum Field Theory In Curved Spacetime - Department of Physics at UF

Quantum Field TheoryIn Curved Spacetime

José Roberto VidalUniversidad Autónoma de Madrid

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Why QFT in curved ST?

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Why QFT in curved ST?

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Why QFT in curved ST?

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Why QFT in curved ST?

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 A la Weinberg

Particles vs. fields

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 A la Weinberg

The Poincaré group tells the whole story:

● Based on symmetries

Particles vs. fields

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 A la Weinberg

We need the Fock space.

And so on...

● Based on symmetries

● Multiparticle states

Particles vs. fields

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 A la Weinberg

● Based on symmetries

● Multiparticle states

● Quantum fields are just a tool.

Products of fields

Particles vs. fields

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A la Peskin­Schroeder

● We start with a classical system.Classical people: 

Poisson, Lagrange, Hamilton...

Particles vs. fields

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A la Peskin­Schroeder

● We start with a classical system.

● Canonical quantization.

Diagonalization throughFourier transform:

Particles vs. fields

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A la Peskin­Schroeder

● We start with a classical system.

● Canonical quantization.

● A beatiful metaphore.

Particles are quantized                  excitations of the field

Particles vs. fields

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Part I

QFT in curved ST is like Schwinger effect!

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1+1 FRW universe

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1+1 FRW universe

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     In modes

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And so on...No particles in the dinosaurs era

     In modes

Complete and normalized basis

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    Out modes

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And so on...No particles in the spacecrafts era

Complete         too!!

    Out modes

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?

?

Particles from nowhere

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Particles from nowhere

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Particles from nowhere

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Particles from nowhere

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Particles from nowhere

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Particles from nowhere

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General formalism● Space plus time

Suitable spacetimes

??Clear separation between space an time

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General formalism● Space plus time

Clear separation between space an time

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General formalism● Space plus time

● Solve field equation

Find a complete and normalized collection of modes.

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General formalism● Space plus time

● Solve field equation

Find a complete and normalized collection of modes.

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General formalism● Space plus time

● Solve field equation

Find a complete and normalized collection of modes.

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General formalism● Space plus time

● Solve field equation

● Quantize!

We get automatically awell defined field operatorplus a Hilbert space

The

pyramid

once

again

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General formalism● Space plus time

● Solve field equation

● Quantize!

● Ambiguity

Differents sets of modes give rise to differents “particles”.

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General formalism● Space plus time

● Solve field equation

● Quantize!

● Ambiguity

Differents sets of modes give rise to differents “particles”.

Bogoliubov transformations

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General formalism● Space plus time

● Solve field equation

● Quantize!

● Ambiguity

● And much more!

Many other observables

● Expectation values

     EM Tensor

● Transition rates

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Part II

QFT in curved ST is not Schwinger effect!

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This is not Schwinger effect!

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What particles?!?

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What particles?!?

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Bonus

Horizons and temperature

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Bonus 1: Minkowski STAccelerated observer

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Bonus 2: de Sitter ST

Time

Horizo

n

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Bonus 3: Black Holes

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Accelerated observer

Unruh effect

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Unruh effect

Rindler ST

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Unruh effect

And of course        we already had

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Unruh effect

Final surprise!

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Hawking Radiation

Two kinds of observers/vacua

or

Anyway

when comparing             or

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● Birrel and Davies, Quantum Fields in Curved Space

● V. Mukhanov, Introduction to Quantum Effects in Gravity

● R. Wald, Quantum Field Theory in Curved Space­time and Black Hole Thermodynamics

● S.A. Fulling, Aspects of Quantum Field Theory in Curved Space­Time

Further reading