|MadSci Network: Physics|
Hi Eduardo, Gravity is one of the weakest forces around: if it weren't for the facts that it works over such large distances and that it is always attractive, we might not even notice it at all. Certainly on the scale of atoms and molecules where quantum mechanical effects are important the effects of gravity are negligible, and similarly on the scale of stars and galaxies where gravity becomes dominant we can ignore quantum effects. So at present we have the theory of general relativity and the theory of quantum mechanics, two extremely successful theories that don't generally overlap. But physicists aren't satisfied with having a theory of gravitation which is still essentially 'classical' (ie it doesn't consider quantum effects). One of the biggests quests in modern day physics is to find a 'grand unified theory' (aka GUT) that joins all types of forces. This would include finding a theory of 'quantum gravity', and in this type of theory the gravitational force would be transmitted by virtual particles called 'gravitons'. For more on gravitation you can check out the answer to a similar MadSci question 'Gravity' or look in "Gravity's Fatal Attraction" by Mitch Begelman and Martin Rees. Cheers, Meghan
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