TED Conversations

Sean Carroll

theoretical physicist,


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LIVE TED Conversation: Join TED Speaker Sean Carroll

LIVE conversation with cosmologist Sean Carroll, TEDxCaltech Speaker and author of From Eternity to Here: The Quest for the Ultimate Theory of Time.

The conversation will open at 4pm (Eastern Standard Time), May 19, 2011. Sean is on vacation in Las Vagas, and will join us from his hotel room there to discuss the cosmos, the nature of time, and the science of poker.


Closing Statement from Sean Carroll

Thanks for participating, everyone! I hope some light was shed. It's been a pleasure chatting with the TED community.

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  • May 19 2011: Hi Dr Caroll, what are your thoughts on the resolution of the Turok measurement problem of inflation via a matter bounce from loop quantum cosmology. Does such a bounce if real imply singualrities cant form and what does it mean for the validity of the Guth Borde Vilenkin theorem that says inflation must have a singularity at the beginning?
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      May 19 2011: The Guth-Borde-Vilenkin theorem doesn't really say there must be singularities. They made some assumptions, and those assumptions might not apply to the real world. Most crucially, they are only talking about classical spacetimes, not quantum gravity. Everyone believes (or should believe) that singularities aren't "real" in quantum gravity; but we don't know what takes their place.

      I'm not very optimistic about loop quantum cosmology or loop quantum gravity more generally, but I'm happy to be proven wrong.

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