Is It Known For Sure Infinites In QFT Are Caused Using a Continuum?

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Discussion Overview

The discussion revolves around the origins of infinities in Quantum Field Theory (QFT), particularly whether these infinities are inherently linked to the use of a continuous model of space and time. Participants explore the implications of continuity versus discretization in theoretical frameworks, including effective field theories (EFT) and lattice models.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant cites a source suggesting that the idealization of physical space as continuous (R3) leads to infinities in QFT, questioning whether this has been definitively proven.
  • Another participant asserts that UV infinities arise from the continuum model, while IR infinities stem from infinite spatial and temporal extensions, claiming certainty about this understanding.
  • A different viewpoint references the Nielson-Ninomiya theorem, suggesting it prevents a fundamental lattice structure in spacetime and posits that infinities in QFT are due to unphysical bare coupling constants.
  • One participant expresses disagreement with the previous claim regarding the Nielson-Ninomiya theorem, linking to a related discussion on lattice field theories.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between continuity and infinities in QFT, with some asserting certainty about the connection while others challenge the implications of the Nielson-Ninomiya theorem. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Participants reference various theoretical frameworks and theorems, indicating a reliance on specific definitions and assumptions that may not be universally accepted. The discussion highlights the complexity of the issues surrounding infinities in QFT without reaching a consensus.

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I am reading WHAT IS A QUANTUM FIELD THEORY?" A First Introduction for Mathematicians.

The author states (2.4 Finite versus Continuous Models) that the use of continuity causes the infinities in QFT:

'Mathematicians are trained to think of physical space as R3. But our continuous model of
physical space as R3 is of course an idealization, both at the scale of the very large and
at the scale of the very small. This idealization has proved to be very powerful, but in the
case of Quantum Field Theory, it creates multiple problems, and in particular the infamous
infinities (in the form of diverging integrals).'

I think that, based on what I have read, it is a likely cause, but has it been proven?

It is not an issue in EFT because a cutoff is used to get finite answers. Could a cutoff be looked at as approximating a lattice model?

Thanks
Bill
 
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There are two kinds on infinities in QFT, UV infinities and IR infinities. UV infinities are due to using a continuum (in both space and time), while IR infinities are due to using infinite extension (in both space and time). And yes, it is known for sure that this is the case.
 
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I've always been under the impression that the Nielson-Ninomiya theorem precludes the possibility of spacetime having a fundamental lattice-type structure, and that the infinities that appear in QFT a result of using the unphysical bare coupling constants🤔
 
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