Originally posted by DeepThought
The speed of light is an input into Maxwell's equations it's not really predicted by them, unless you regard the permittivity and permeability of free space as more fundamental constants - which most people don't.
In answer to the person who started the thread, the explanation for gravity is that massive objects cause the spacetime around them to be c ...[text shortened]... s the observation - things are as they are. You may as well ask why one and one make two.
It depends how you see at things. 1+1=2 is a result of deeper rules of the number system and its operations. 1+1=2 is not at all a basic rule. Mathematics is an axiomatic system.
I see, and some others, physics as axiomatic too. In my philosophy there are some very basic rules that governs the universe, the axioms of the Universe. And this is what the string theory is all about.
Is velocity of light a basic constant of nature? Or is it a result of more basic constants or parameters in the equations of string theory? Does the velocity of light really have to be (near to) 300 000 km/s? Or does the Universe permit it to be faster or slower? Is it even a constant over times? No observational proofs are given, perhaps the equations can give some answers.
The same thing about gravity. Is there a reason for the gravitational constant to be what is is? Does it change over times? Does it have to be a gravitation at all? Is there a negative gravitation (like the magnetic force)?
I say that gravity is only a solution of the equations of string theory. There are more basic reasons to the existence of gravity and its force. I say that there are axioms, known by mankind, not yet known by mankind, or perhaps, not ever known by mankind but still there. These axioms can be described by equations where the solutions explains it all.
Gravity is there because it cannot be otherwise due to equations. that's why.