Lubos Motl
Aug19-04, 07:50 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>On Tue, 17 Aug 2004, Urs Schreiber wrote:\n\n> On Tue, 17 Aug 2004, A.J. Tolland wrote:\n>\n> > If you want to explain this peculiarity by saying that Lorentz is\n> > always extended to diff, that\'s fine. Maybe even a nice piece of evidence\n> > for string theory.\n>\n> How is that evidence for string theory?\n\nI have not read all the previous postings in the thread, but there are\nobvious answers.\n\nFirst, string theory does not seem to have any global continuous\nsymmetries. All continuous symmetries seem to be extended to gauge groups.\nPerturbatively, it is easy to see that a current on the worldsheet,\ngenerating a symmetry, can be multiplied by an operator (del X, roughly\nspeaking) to obtain a vertex operator of the corresponding gauge boson,\nproving that the symmetry is local. There are no reasons to believe that\nthis statement is violated non-perturbatively, as far as I know. But many\nwisdoms have already been violated, and we may see a counterexample...\n\nIf you apply it to the Lorentz symmetry, you sort of automatically derive\nthat string theory must contain gravity if it contains Lorentz-invariant\nphysics anywhere.\n\nIf someone proves that this extension must always hold, it is a\nconsistency check against string theory. Also, LQG as a self-proclaimed\ncompetitor of string theory has serious problems with Lorentz symmetry,\nand any argument that supports that gravity is an extension of the Lorentz\nsymmetry - as Einstein originally meant - and not some random emergent\nphenomenon arising from an obscure discrete model - is therefore helping\nto nail LQG back to its coffin, which is also an indirect argument in\nfavor of string theory. At least relatively speaking. ;-)\n_______________________________________________ _______________________________\nE-mail: lumo@matfyz.cz fax: +1-617/496-0110 Web: http://lumo.matfyz.cz/\neFax: +1-801/454-1858 work: +1-617/496-8199 home: +1-617/868-4487 (call)\n^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>On Tue, 17 Aug 2004, Urs Schreiber wrote:
> On Tue, 17 Aug 2004, A.J. Tolland wrote:
>
> > If you want to explain this peculiarity by saying that Lorentz is
> > always extended to diff, that's fine. Maybe even a nice piece of evidence
> > for string theory.
>
> How is that evidence for string theory?
I have not read all the previous postings in the thread, but there are
obvious answers.
First, string theory does not seem to have any global continuous
symmetries. All continuous symmetries seem to be extended to gauge groups.
Perturbatively, it is easy to see that a current on the worldsheet,
generating a symmetry, can be multiplied by an operator (del X, roughly
speaking) to obtain a vertex operator of the corresponding gauge boson,
proving that the symmetry is local. There are no reasons to believe that
this statement is violated non-perturbatively, as far as I know. But many
wisdoms have already been violated, and we may see a counterexample...
If you apply it to the Lorentz symmetry, you sort of automatically derive
that string theory must contain gravity if it contains Lorentz-invariant
physics anywhere.
If someone proves that this extension must always hold, it is a
consistency check against string theory. Also, LQG as a self-proclaimed
competitor of string theory has serious problems with Lorentz symmetry,
and any argument that supports that gravity is an extension of the Lorentz
symmetry - as Einstein originally meant - and not some random emergent
phenomenon arising from an obscure discrete model - is therefore helping
to nail LQG back to its coffin, which is also an indirect argument in
favor of string theory. At least relatively speaking. ;-)
__{_______________________________________________ _____________________________}
E-mail: lumo@matfyz.cz fax: +1-617/496-0110 Web: http://lumo.matfyz.cz/
eFax: +1-801/454-1858 work: +1-617/496-8199 home: +1-617/868-4487 (call)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> On Tue, 17 Aug 2004, A.J. Tolland wrote:
>
> > If you want to explain this peculiarity by saying that Lorentz is
> > always extended to diff, that's fine. Maybe even a nice piece of evidence
> > for string theory.
>
> How is that evidence for string theory?
I have not read all the previous postings in the thread, but there are
obvious answers.
First, string theory does not seem to have any global continuous
symmetries. All continuous symmetries seem to be extended to gauge groups.
Perturbatively, it is easy to see that a current on the worldsheet,
generating a symmetry, can be multiplied by an operator (del X, roughly
speaking) to obtain a vertex operator of the corresponding gauge boson,
proving that the symmetry is local. There are no reasons to believe that
this statement is violated non-perturbatively, as far as I know. But many
wisdoms have already been violated, and we may see a counterexample...
If you apply it to the Lorentz symmetry, you sort of automatically derive
that string theory must contain gravity if it contains Lorentz-invariant
physics anywhere.
If someone proves that this extension must always hold, it is a
consistency check against string theory. Also, LQG as a self-proclaimed
competitor of string theory has serious problems with Lorentz symmetry,
and any argument that supports that gravity is an extension of the Lorentz
symmetry - as Einstein originally meant - and not some random emergent
phenomenon arising from an obscure discrete model - is therefore helping
to nail LQG back to its coffin, which is also an indirect argument in
favor of string theory. At least relatively speaking. ;-)
__{_______________________________________________ _____________________________}
E-mail: lumo@matfyz.cz fax: +1-617/496-0110 Web: http://lumo.matfyz.cz/
eFax: +1-801/454-1858 work: +1-617/496-8199 home: +1-617/868-4487 (call)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^