Smolin contributes idea about testing String

[marcus]

This just out:
http://arxiv.org/hep-th/0401087
Joao Magueijo <j.magueijo@ic.ac.uk>
Lee Smolin

"String theories with deformed energy momentum relations, and a possible non-tachyonic bosonic string"

Smolin is one of the inventors of Loop gravity but also has
authored and co-authored a number of string papers as well.

Here they are basically saying "Hey look, GLAST goes into orbit and begins observations in 2006---providing the first real test of some variant(s) of Loop quantum gravity. String should get ready for this by making its predictions too! And then, because they are such helpful people, and because they see that the string regulars have neglected to do it, they tinker around with seeing how to get the string machinery to come out with some predictions that GLAST, or maybe some high-energy cosmic ray project might test.

Other takes on the paper are welcome. What I am picking up on is
their looking for dispersion relations like the energy-dependent speed of light---and, failing to find that, other effects kindred to it.

 

[ranyart]

Originally posted by marcus
This just out:
http://arxiv.org/hep-th/0401087
Joao Magueijo <j.magueijo@ic.ac.uk>
Lee Smolin

"String theories with deformed energy momentum relations, and a possible non-tachyonic bosonic string"

Smolin is one of the inventors of Loop gravity but also has
authored and co-authored a number of string papers as well.

Here they are basically saying "Hey look, GLAST goes into orbit and begins observations in 2006---providing the first real test of some variant(s) of Loop quantum gravity. String should get ready for this by making its predictions too! And then, because they are such helpful people, and because they see that the string regulars have neglected to do it, they tinker around with seeing how to get the string machinery to come out with some predictions that GLAST, or maybe some high-energy cosmic ray project might test.

Other takes on the paper are welcome. What I am picking up on is
their looking for dispersion relations like the energy-dependent speed of light---and, failing to find that, other effects kindred to it.

Marcus, I have the greatest respect for Smolin and Magueijo, their insights seem to be true and are making the right moves.

The paper has to be viewed a number of times, but my personal opinion is that there will be no evidence for the proposed tests.

 

[marcus]

our views are probably fairly similar, ranyart,
my hunch is that GLAST will find no energy-dependence
in the speed of light
but it certainly might

and it seems that the time to make predictions
is before the experiment is done
so one would think that quantum gravity folk of
every stripe would be interested in sorting
out which versions of which theories predict the effect
and which dont.

It was so much more informative that the Microwave Background
was predicted in 1945 on GR grounds and then twenty years later
it was detected
than if they had detected it, say, in 1965 and said "hey, what is
that funny buzz in the sky? do you suppose it could be the
stretched out waves of the glow from a hotter denser time? why
yes, that would explain the buzz wouldn't it?"

so Smolin and Magueijo are shaking the box
of string theory to see if there are any predictions
rattling around in it
prior to the great 2006 event

I share your respect and approve of the initiative they're taking
still need to go back and see what else I can glean from the paper
cheers,
m

 

[jeff]

Originally posted by marcus
because they [LQG'ers] are such helpful people, and because they see that the string regulars have neglected to do it, they tinker around with seeing how to get the string machinery to come out with some predictions that GLAST, or maybe some high-energy cosmic ray project might test.

This is an idiotic remark.

 

[Nereid]

ranyart wrote: The paper has to be viewed a number of times, but my personal opinion is that there will be no evidence for the proposed tests.

Why (not)?

marcus also ("my hunch is that GLAST will find no energy-dependence in the speed of light but it certainly might")

 

[marcus]

Originally posted by Nereid
Why (not)?

marcus also ("my hunch is that GLAST will find no energy-dependence in the speed of light but it certainly might")

well Nereid it's an aesthetic bias of mine
I confess one should keep an open mind and wait for the experimental results and not prejudge but 2006 is a long time to hold off from having a bias, so I just have this bias

I like the versions of LQG and DSR which have an absolute constant speed of light. To the extent of my understanding, they seem more beautiful than those versions with an energy-dependent speed of light. I am a sucker for constancy in the fundamental physical constants.

But, gritting my teeth at the unappetizing prospect, we have to admit that GLAST might find energy-dependence in the speed of light.

What about you. Fair is fair and you asked me. Do you have any kind of hunch or preference as regards energy-dependence?

 

[Nereid]

marcus wrote: What about you. Fair is fair and you asked me. Do you have any kind of hunch or preference as regards energy-dependence?

No. What I would really like to see is something totally unexpected, that underlines Haldane's comment in spades.

 

[Tsu]

According to the official NASA GLAST Website, as of 1/15/04 the launch is now scheduled for February 2007.

edit: here's the page
http://glast.gsfc.nasa.gov/

 

[marcus]

Originally posted by Tsunami
According to the official NASA GLAST Website, as of 1/15/04 the launch is now scheduled for February 2007.

edit: here's the page
http://glast.gsfc.nasa.gov/

Yes

those instruments they put in orbit to observe the sky are among the finest human accomplishments

only just now beginning to realize how beautiful they are

pity if (as Nereid fears) GLAST is sacrificed to an expanded
manned-space budget