I was reading an article in Wikipedia about loop quantum gravity.

http://en.wikipedia.org/wiki/Loop_quantum_gravity

In the article they say the following:
"This is not the most popular theory of quantum gravity; many physicists have philosophical problems with it."

I like to know what these philisophical problems are. Can someone help me with this?

Thanks in advance

Thomas

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There is no way to happiness,
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Hum,
i don`t know.

Perhaps they ment that it only deals with gravity and cannot be extended to include the other forces and particles.

<Added>
As opposed to string/m-theory that promises to included all the forces.
</Added>

http://en.wikipedia.org/wiki/Philosophical

Thats all I could find...

..Hope it helps.

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There is a nice article on QLG in the current special issue of Scientific American. The issue also contains an article on string theory in which Brian Greene's comments include some optimstic remarks about QLG (he calls it "a viable approach," and expresses the hope that ST theorists and QLG theorists are "developing the same the same theory from different angles" and says that they might eventually "meet someplace"*).

*p53

Personally I can't feel too thrilled about any scientific article that makes this statement without careful clarification of what is meant. At face value, the statement has many nonscientific aspects, such as the use of the terms "popular" and "philosophical problems". Although both these terms do play a role in the way science gets done in practice, neither are appropriate for testing the validity of a theory, only for personal decisions about what theory one might want to spend their precious time on. If read incorrectly, the statement tends to suggest incorrect things about the nature of science, i.e., that it is a popularity contest based on philosophical preferences. Rather, it is based on evidence, utility, and economy of effort, and the preference issues appear when choosing between valid theories that already exist to explain the data (which rarely happens anyway). Nevertheless, scientists are humans, and will have their preferences when thinking about things that are as yet unsolved.

Thanks for your replies. The article suggested to me there were some specific "well-known" philosophical problems with this theory. I wondered what kind of philisophical problems you can have with a scientific theory.

__________________
Not because it is easy, but because it is hard...

There is no way to happiness,
happiness is the way.

Hum,
Is it beautiful?

That's certainly a good question. Should a good theory be beautiful?
I feel that per definition any theory that gives a good formulation of the universe is beautiful. Even when it may seem ugly at first, it will become beautiful.

__________________
Not because it is easy, but because it is hard...

There is no way to happiness,
happiness is the way.