Monday, September 18, 2017

gravity - what is this force that is able to surpass an entire planet's force on it?


I have a wet teabag in an empty cup. If I will hold the teabag and touch the wall of cup with it, it will stick to the cup, like there would be glue or some magnetic field, but there's just water.


enter image description here


So, why does it happens? Why can just a little bit of water hold the teabag stronger than the gravity of an entire planet so it will not fall to the bottom of the cup, or even slide down a little bit?


Why is it so strong?



Answer



Based on your comment, I think you are indeed asking a more profund question than your teabag suggests:



Why is it that gravity is so weak compared to the other forces?


The answer is: We don't know. Seriously, that is one of the holy grails: To first find the Grand Unified Theory of nature in which all forces except gravity are explained as coming from one single symmetry group which is broken at our normal energies, and to then find the Theory of Everything that understands all four fundamental forces with a single, unified concept. In such a theory, it is hoped, the differences between the forces emerge naturally, instead of just being put in by measuring the relative strengths experimentally.


But we don't know yet. we don't know which of the manifold concepts that are at the forefront of theoretical thinking right now might turn out to be indeed the ones realized in nature. But the question why gravity is so weak is really still unsolved.


String theorists let gravity act in other dimensions, thereby weakening it in our four comparative to the others.


Others employ a form of the anthropic principle to argue that only in a universe where gravity is as weak as here life could have evolved and asked that question, so there is no deeper reason except that, for us to be here, it has to be like that.


I apologize to all those whose theory I cannot name and briefly, unjustifiedly compress into a few words off the top of my head.


That's it. We really don't know.


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