Conversations in string theory

doi:10.1017/CBO9780511920998.018

18 - Conversations in string theory

Published online by Cambridge University Press: 05 August 2012

Jeff Murugan and

Edited by

Amanda Weltman and

Amanda Weltman: Affiliation:
University of Cape Town
Jeff Murugan: Affiliation:
University of Cape Town
George F. R. Ellis: Affiliation:
University of Cape Town
Jeff Murugan: Affiliation:
University of Cape Town
Amanda Weltman: Affiliation:
University of Cape Town
George F. R. Ellis: Affiliation:
University of Cape Town

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Summary

In this closing chapter we thought it only fitting to reintroduce Thanu Padmanabhan's Hypothetically Alert Relativist Open to Logical Discussions (Harold) who, having engaged much with the popular media and with his classical relativist background, has some probing questions about string theory. Making her debut here as his correspondent is Steph, a ‘String Theorist of Endless Patience and some Humility’.

Harold: It seems to me that there has been an enormous amount of resources spent on the various quantum gravity programs. Is there an actual proof that gravity has to be quantized at all?

Steph: Well, that depends on what you think would constitute a proof. Does classical mechanics have to be quantized? Apparently. Do we have a proof to that effect? No. We have a theory, it makes predictions and seems to agree with nature so we accept it. By the nature of the whole enterprise though, if we encounter a prediction that is wrong then we have to give up the theory. So, does gravity need to be quantized? I don't know. What I do know is that it is a fundamental interaction. The other three fundamental interactions all seem to have consistent quantum descriptions and, personally, I find that three out of four having quantum descriptions and only one being completely classical is unappealing. But maybe this is just the way nature is.

Harold: Where does the need to quantize gravity come from except for a belief in unification which may or may not be satisfied in reality?

Steph: I would say that it comes from a belief that at sufficiently small scales all the interactions exhibit quantum behaviour.

Type: Chapter
Information: Foundations of Space and Time
Reflections on Quantum Gravity
, pp. 419 - 434

DOI: https://doi.org/10.1017/CBO9780511920998.018 [Opens in a new window]

Publisher: Cambridge University Press

Print publication year: 2012

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