11-24-2007, 11:07 AM
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#3 (permalink)
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Join Date: Oct 2007 Location: BC Canada, near the US border
Posts: 1,351
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Quote:
Originally Posted by Og  | Thanks Og .... I'll look forward to reading this when my New Scientist arrives
But it seems like all these theories it has a long way to go before the theory of everything is home and dry: Quote:
Sabine Hossenfelder of the Perimeter Institute for Theoretical Physics, who recently arranged for Lisi to address an international meeting on loop quantum gravity, and who is thanked in Lisi's paper as having been a useful correspondent, nevertheless stresses the limitations of the work, commenting:
How can I possibly say that clearer: Given today's status,
Garrett's model does *not* naturally lead to a unification of the Standard Model interactions with gravity (he has to choose the action by hand that contains both),
it does *not* allow us to understand quantum gravity (since there's nothing said about quantization);
it does *not* explain the parameters in the SM (since there isn't yet a mechanism for symmetry breaking);
it does *not* explain the cosmological constant or its value (as said above, to claim there has to be one, it would be necessary to show there's no way to do it without one);
it does *not* explain the hierarchy problem (and I see no way to do so);
it does *not* explain why we live in a spacetime with 3 spatial and 1 time-like dimensions.[10]
Overall she is undecided about her feelings towards the theory. She writes that for her, "the attractive and the unattractive features seem to balance each other. To me, the most attractive feature is the way he uses the exceptional Lie-groups to get the fermions together with the bosons. The most unattractive feature are the extra assumptions he needs to write down an action that gives the correct equations of motion".[11]
She also has technical concerns about the lack of coupling constants in the paper, which thus appears to rely on pulling a particular characteristic length scale out of nowhere. However, in the end, she states, "I think Garrett's paper has the potential to become a very important contribution, and his approach is worth further examination."[11]
| But I admit it is pretty
all the best
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There is a theory which states that if ever anybody discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another theory which states that this has already happened. ........... Douglas Adams |
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