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auden
auden
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I am a firm believer of notion of wick rotation. As Lubos nicely pointed out, the most clear indication of wick rotation comes from quantum cosmology. In fact, many new recent results in different models of QGquantum gravity such as loop quantum gravity$^1$ ( see M.Bojowald,J.Mielczarek,A.Barrau,J.Grain, G.Calcagni and othersLQG)  , CDTcausal dynamical triangulation$^2$ ( see Ambjorn,Coumbe, Gizbert-Studnicki and JurkieiwczCDT)  , Nonnon-Commutative Geometry ( See Lizzi, Kurkiv , D'Andrea , ...) commutative geometry$^3$,Horava Horava-Lifshitz Gravity ( see Horava, Melby-Thomson, Kevin Crosvenor / see also K.Crosvenor lecture at GR21 conference 2016) $^4$, Causal Sets ( L.Glaser and S.Surya / also Glasercausal sets$^5$, D.O'Connor and Surya ; forthcoming) and eventually in Superstring-Msuperstring M- Theory ( C.Hull/ Edward Witten / Robbert Dijkgraaf, Ben Heidenreich, Patrick Jeffersontheory$^6$, Cumrun Vafa 2016) strongly indicate that at the very high curvatures near or at the Planck scale ( totallytotally non-perturbative quantum gravitational system  ) the signature of spacetime is not anymore Lorentzian anymore and turns into a quantum version of 4D4-D Euclidean space which is timeless,Acausal acausal and devoidsdevoid of any dynamics or evolution  , describing elegantly the so called No-Bondary Proposal of Hartle-Hawking).

Cheers

$^1$See M.Bojowald, J.Mielczarek, A.Barrau, J.Grain, G.Calcagni

$^2$See Ambjorn, Coumbe, Gizbert-Studnicki, and Jurkieiwcz

$^3$See Lizzi, Kurkiv, D'Andrea, and others

$^4$See Horava, Melby-Thomson, and Kevin Crosvenor, as well as the K. Crosvenor lecture at the GR21 conference 2016

$^5$See L. Glaser and S.Surya, as well as Glaser, D.O'Connor and Surya; forthcoming

$^6$See C.Hull, Edward Witten, Robbert Dijkgraaf, Ben Heidenreich, Patrick Jefferson, and Cumrun Vafa 2016

I am a firm believer of notion of wick rotation. As Lubos nicely pointed out the most clear indication of wick rotation comes from quantum cosmology. In fact many new recent results in different models of QG such loop quantum gravity ( see M.Bojowald,J.Mielczarek,A.Barrau,J.Grain, G.Calcagni and others)  , CDT ( see Ambjorn,Coumbe, Gizbert-Studnicki and Jurkieiwcz)  , Non-Commutative Geometry ( See Lizzi, Kurkiv , D'Andrea , ...) ,Horava-Lifshitz Gravity ( see Horava, Melby-Thomson, Kevin Crosvenor / see also K.Crosvenor lecture at GR21 conference 2016) , Causal Sets ( L.Glaser and S.Surya / also Glaser, D.O'Connor and Surya ; forthcoming) and eventually in Superstring-M- Theory ( C.Hull/ Edward Witten / Robbert Dijkgraaf, Ben Heidenreich, Patrick Jefferson, Cumrun Vafa 2016) strongly indicate that at the very high curvatures near or at the Planck scale ( totally non-perturbative quantum gravitational system  ) the signature of spacetime is not anymore Lorentzian and turns into a quantum version of 4D Euclidean space which is timeless,Acausal and devoids of any dynamics or evolution  , describing elegantly so called No-Bondary Proposal of Hartle-Hawking).

Cheers

I am a firm believer of notion of wick rotation. As Lubos nicely pointed out, the most clear indication of wick rotation comes from quantum cosmology. In fact, many new recent results in different models of quantum gravity such as loop quantum gravity$^1$ (LQG), causal dynamical triangulation$^2$ (CDT), non-commutative geometry$^3$, Horava-Lifshitz Gravity$^4$, causal sets$^5$, and eventually in superstring M-theory$^6$, strongly indicate that at the very high curvatures near or at the Planck scale (totally non-perturbative quantum gravitational system) the signature of spacetime is not Lorentzian anymore and turns into a quantum version of 4-D Euclidean space which is timeless, acausal and devoid of any dynamics or evolution, describing elegantly the so called No-Bondary Proposal of Hartle-Hawking.

Cheers

$^1$See M.Bojowald, J.Mielczarek, A.Barrau, J.Grain, G.Calcagni

$^2$See Ambjorn, Coumbe, Gizbert-Studnicki, and Jurkieiwcz

$^3$See Lizzi, Kurkiv, D'Andrea, and others

$^4$See Horava, Melby-Thomson, and Kevin Crosvenor, as well as the K. Crosvenor lecture at the GR21 conference 2016

$^5$See L. Glaser and S.Surya, as well as Glaser, D.O'Connor and Surya; forthcoming

$^6$See C.Hull, Edward Witten, Robbert Dijkgraaf, Ben Heidenreich, Patrick Jefferson, and Cumrun Vafa 2016

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Kaveh
Kaveh
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I am a firm believer of notion of wick rotation. As Lubos nicely pointed out the most clear indication of wick rotation comes from quantum cosmology. In fact many new recent results in different models of QG such loop quantum gravity ( see M.Bojowald,J.Mielczarek,A.Barrau,J.Grain, G.Calcagni and others) , CDT ( see Ambjorn,Coumbe, Gizbert-Studnicki and Jurkieiwcz) , Non-Commutative Geometry ( See Lizzi, Kurkiv , D'Andrea , ...) ,Horava-Lifshitz Gravity ( see Horava, Melby-Thomson, Kevin Crosvenor / see also K.Crosvenor lecture at GR21 conference 2016) , Causal Sets ( L.Glaser and S.Surya / also Glaser, D.O'Connor and Surya ; forthcoming) and eventually in Superstring-M- Theory ( C.Hull/ Edward Witten / Robbert Dijkgraaf, Ben Heidenreich, Patrick Jefferson, Cumrun Vafa 2016) strongly indicate that at the very high curvatures near or at the Planck scale ( totally non-perturbative quantum gravitational system ) the signature of spacetime is not anymore Lorentzian and turns into a quantum version of 4D Euclidean space which is timeless,Acausal and devoids of any dynamics or evolution , describing elegantly so called No-Bondary Proposal of Hartle-Hawking).

Cheers