Read Witten's Reflections on Spacetime

[twistor]

I found an now historical article of witten speaking about the fate of spacetime, and I wanted to share it with you.

Here it goes:
http://www.sns.ias.edu/~witten/papers/Reflections.pdf


I hope you enjoy it

 

[Spinnor]

Thanks! Somewhere I have buried a photocopy of this paper.

 

[twistor]

I think it is paradoxical that Witten thought that string theory was going to change the way we think about space time, but at the end string theory is background dependent (at least in its current formulation*)*It should be noted that, in spite of what I've said above, I have several reasons (mainly coming from dualities, holography, Matrix String Theory and String Field Theory) to believe that a background independent formulation of string theory is possible.

 

[julian]

It is in the book "Physics Meets Philosophy at the Planck Scale".

I think Witten has always been well aware of the need for a background independent quantization of gravity (perhaps unlike a lot of stringy people lower down in the hierarchy). I think a while back there had been a kind of feeling that once the infinities of perturbative quantum gravity were tamed, the conceptual difficulties would some how fall in place...

But along the way they may have found things that indicate the need to revise notions of spacetime.

 

[twistor]

Is twistor theory Background Independent?

 

[julian]

Is twistor theory Background Independent?

I think twistor theory is only partially background independent in that the emphasis is shifted away from the metric description to an abstract mathematical space (twistor space) however the twistor description retains the information about the light cone or conformal structure of space-time. As Penrose envisaged it, the light cone structure is fixed while the other degrees freedom are subject to quantum fluctuations.

I think, possibly, there was some point in the 1980's that Witten favoured twister theory to provide the most promising way of formulating a background independent theory of strings, but he found that a lot of the nice features of twistor theory that hold in 4 dimensions don't extend to higher dimensions and so abandoned it.

 

[haushofer]

I wonder how this article would look like now, almost twenty years later :)

 

[Rexcirus]

Twistor: Many thanks for the article!
Very interesting the link between the usual four dimensional space time and the two dimensional conformal field theory.

 

[twistor]

Twistor: Many thanks for the article!
Very interesting the link between the usual four dimensional space time and the two dimensional conformal field theory.

If you liked the article you may also like:

http://www.sns.ias.edu/~witten/papers/duality.pdf
http://www.sns.ias.edu/~witten/papers/mmm.pdf
http://www.sns.ias.edu/~witten/papers/Holes.pdf
http://www.sns.ias.edu/~witten/papers/Mass.pdf
http://www.sns.ias.edu/~witten/papers/higgs.pdf (before the discovery of the Higgs boson)
http://www.sns.ias.edu/~witten/papers/string.pdf *
http://www.sns.ias.edu/~witten/papers/CurrentScienceVol81.pdf
http://www.sns.ias.edu/~witten/papers/BlackHoles.pdf
http://www.sns.ias.edu/~witten/papers/Symmetry.pdf *
http://www.sns.ias.edu/~witten/papers/Unravelling.pdf *
http://www.sns.ias.edu/~witten/papers/KnotsandPhysics.pdf *

*most accesible

 

[twistor]

I wonder, what are Witten´s current views on spacetime in the context of string/M Theory?

 

[twistor]

I wonder, what are Witten´s current views on spacetime in the context of string/M Theory?

Does he still believe that spacetime is emergent?

 

[twistor]

Here I found and interesting paper:
http://arxiv.org/pdf/hep-th/9306122.pdf