Category Archives: Uncategorized

David Wallace Talk This Week

Wednesday 17 October 2018 at UIC – David Wallace (Southern California): Why black hole information loss is paradoxical

Abstract: I distinguish between two versions of the black hole information-loss paradox. The first arises from apparent failure of unitarity on the space- time of a completely evaporating black hole, which appears to be non- globally-hyperbolic; this is the most commonly discussed version of the paradox in the foundational and semi-popular literature, and the case for calling it ‘paradoxical’ is less than compelling. But the second arises from a clash between a fully-statistical-mechanical interpretation of black hole evaporation and the quantum-field-theoretic description used in derivations of the Hawking effect. This version of the paradox arises long before a black hole completely evaporates, seems to be the version that has played a central role in quantum gravity, and is genuinely paradoxical. After explicating the paradox, I discuss the implications of more recent work on AdS/CFT duality and on the ‘Firewall paradox’, and conclude that the paradox is if anything now sharper. The article is written at a (relatively) introductory level and does not assume advanced knowledge of quantum gravity.

11.15am local Chicago time, 1430 University Hall — or via Skype to the University of Geneva talks in room L208.

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THE NEVER-ENDING DANCE OF PHILOSOPHY AND PHYSICS

And another video – a talk by Josh Norton and Nick Huggett, aimed at a popular audience, discussing the relation between physics and philosophy, using examples from early modern science and from quantum gravity. https://youtu.be/JxZZ6Wv_uaI

Smolin and Wüthrich video posted

A couple of nice new videos just posted:

First Lee Smolin’s amazing lecture from the Midwest Summer School, reflecting on the strengths and weaknesses of different approaches to QG, and his reflections on where to go from here: https://beyondspacetime.net/summer-school-2018/msspp1-lecture-abstracts/

Second Chris’ lecture from the Split summer school on black hole entropy and holography: https://youtu.be/zDqgsGUcVcA

Enjoy!

Thanks to the John Templeton Foundation

Greetings from Beyond Spacetime at the start of the new academic year!

A big thank you the John Templeton Foundation, for their generous support over the past three years; this website documents much of what we achieved. While the grant has now expired, Beyond Spacetime activities will continue, including speakers to be announced here soon – watch this space!

New Video

We have just posted some new videos to our YouTube channel: a 100-level lecture on spacetime from Tushar Menon and James Read, and a pair of 200-level lectures on dualities by Keizo Matsubara. There is also a stack of new talks, including Erik Curiel’s Two Paths to the Einstein Field Equation from Horizon Thermodynamics. Find the link above, or from the speaker page above. Enjoy!

Public talk by Fay Dowker, Geneva, 17 May 2018

I would like to draw your attention to the following public talk, which is organized by the “service de communication” of the University of Geneva, with the support of the Geneva Symmetry Group (https://genevasymmetrygroup.wordpress.com/):

Thursday, 17 May 2018, 18h30, Uni Dufour (room will be advertised):

Fay Dowker, Professor of Theoretical Physics, Imperial College London:

Past, Present and Future: The Science of Time
(The talk will be in English, with simultaneous translation into French.)

(Dedicated to the memory of Professor Stephen Hawking)

Opening of the conference by Professor Christian Wüthrich, Geneva Symmetry Group, Department of Philosophy, Geneva

For more information (with an abstract in English), please visit https://www.unige.ch/public/actualites/2018/la-science-du-temps/

Hawking

We note the passing of Stephen Hawking, whose contributions to our field cannot be calculated (not even using zeta function regularization). To mention one item beautiful work, that influenced me, and which not everyone seems to know, there is the series of contrasting lectures and dialogues with Roger Penrose (and others): The Nature of Space and Time. So full of insights, and revealing of their different personal axioms, but so understanding and respectful of each other, I thoroughly recommend it in many ways.

A different kind of work, Hawking is the titular star of the most recent installment (the hexagonal phase) of The Hitchhiker’s Guide to the Galaxy. Also recommended in many ways.