[The Lone Ranger]

The astrophysicist Martin Rees has pointed out that gravity is 1036 times weaker than the electromagnetic force. Accordingly, he argues, if gravity were a million times stronger, and "only" 1030 times weaker than the electromagnetic force, complex life in our Universe would probably be impossible.

His argument is that if gravity were that strong, even planet-sized objects would have enough gravity to ignite fusion reactions in their cores. Consequently, galaxies would be smaller and more compact, and stars would be so close together that it would be all but impossible for planets around them to have stable orbits. That is, gravitational interactions between the stars in galaxies would all but guarantee that any planet orbiting any of those stars would either be ejected from its orbit or be drawn into a star.



Elaborating on that, I would imagine that if gravity were anywhere near as strong as the electromagnetic force (say, only 1010 weaker), the collective gravity of the Universe's matter would easily have overwhelmed any expansion pressure, and so the Universe would have collapsed upon itself soon after the Big Bang.

In short, if gravity weren't many, many orders of magnitude weaker than the other fundamental forces, it seems all but certain that the Universe simply couldn't exist, as it would almost-certainly have collapsed upon itself soon after it came into existence.


Cheers,

Michael