Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Smolin contributes idea about testing String

  1. Jan 17, 2004 #1

    marcus

    User Avatar
    Science Advisor
    Gold Member
    2015 Award
    Dearly Missed

    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.
     
    Last edited: Jan 17, 2004
  2. jcsd
  3. Jan 18, 2004 #2
    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.
     
  4. Jan 18, 2004 #3

    marcus

    User Avatar
    Science Advisor
    Gold Member
    2015 Award
    Dearly Missed

    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 wouldnt 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
     
  5. Jan 18, 2004 #4

    jeff

    User Avatar
    Science Advisor

    This is an idiotic remark.
     
  6. Jan 18, 2004 #5

    Nereid

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Why (not)?

    marcus also ("my hunch is that GLAST will find no energy-dependence in the speed of light but it certainly might")
     
  7. Jan 18, 2004 #6

    marcus

    User Avatar
    Science Advisor
    Gold Member
    2015 Award
    Dearly Missed

    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?
     
  8. Jan 18, 2004 #7

    Nereid

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    No. What I would really like to see is something totally unexpected, that underlines Haldane's comment in spades.
     
  9. Jan 25, 2004 #8

    Tsu

    User Avatar
    Gold Member

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

    edit: here's the page
    http://glast.gsfc.nasa.gov/
     
  10. Jan 25, 2004 #9

    marcus

    User Avatar
    Science Advisor
    Gold Member
    2015 Award
    Dearly Missed

    Yes :frown:

    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
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Smolin contributes idea about testing String
  1. Smolin talks about E8 (Replies: 23)

Loading...