Electric vs gravitational force

[g.lemaitre]

In the First Three Minutes Weinberg wrote:

If the Earth and the sun had an excess of positive over negative charges (or vice versa) of only one part in (10^36), the electrical repulsion between them would be greater than their gravitational attraction.

How would that imbalance actually manifest itself in the real world? Does that mean that if for every 10^36 protons the sun had 10^36 + 1 electrons and if the Earth for every 10^36 electrons had 10^36 + 1 protons, then that would knock the Earth out of orbit? At first glance it seems ridiculous but considering the fact that the Earth has 10^50 protons that means that the Earth would have, I think, 10^14 extra protons than electrons, but even 10^14 electrons is hardly a lot considering that a mole is 10^23. My math must be off somehow.

 

[jtbell]

I think Weinberg must have omitted a square root in his calculation. I get a ratio of about 10^18, not 10^36.

 

[g.lemaitre]

No, I've seen that figure quotes about 20 times, sometimes I see it quoted as 10^36 times stronger, other times 10^40 times stronger. Here's one link

electricuniversetheory.com

 

[jtbell]

Try it yourself. Calculate the gravitational force between the sun and earth. Then calculate the electric force assuming a surplus of protons of 10^-36 times the actual number on the sun and earth, and the electric force assuming a proton surplus of 10^-18. Which one is closer?

For a more precise value, use 8.998 x 10^-19 for the "surplus proton" ratio.

 

[rbj]

the issue is, that two protons alone in free space will have a $1/r^2$ gravitational force that is attractive and another $1/r^2$ electrostatic force that is repulsive. since they are both $1/r^2$, it doesn't matter what distance the protons are from each other (at least in this classical setting). so which force is stronger? the attractive gravitational force (that depends on the masses of the two protons) or the repulsive electrostatic force (that depends on the charges of the two protons)? and by how much?

 

[g.lemaitre]

the issue is, that two protons alone in free space will have a $1/r^2$ gravitational force that is attractive and another $1/r^2$ electrostatic force that is repulsive. since they are both $1/r^2$, it doesn't matter what distance the protons are from each other (at least in this classical setting). so which force is stronger? the attractive gravitational force (that depends on the masses of the two protons) or the repulsive electrostatic force (that depends on the charges of the two protons)? and by how much?

I'm pretty sure the EM force would matter in your above example. What I'm worried about though is how much of an imbalance of electrons over protons you need on the Earth and Sun before the Earth gets forced out of orbit, provided the Earth has 10^50 protons and the Sun 10^57 protons.

 

[xAxis]

... At first glance it seems ridiculous but considering the fact that the Earth has 10^50 protons that means that the Earth would have, I think, 10^14 extra protons than electrons,... My math must be off somehow.

Actually the Earth would have only one more proton

 

[Blahboy]

Since were on the topic of gravity how does the sun's gravity prevent it from blowing up into space? Because if its energy comes from nuclear fusion wouldn't the pressure from this reaction push the particles away?

 

[g.lemaitre]

Since were on the topic of gravity how does the sun's gravity prevent it from blowing up into space? Because if its energy comes from nuclear fusion wouldn't the pressure from this reaction push the particles away?

The sun is held in perfect equilibrium. Gravity wants to crush it to a point and the pressure from the fusion wants to push it outward. The outward force of fusion and the inward force of gravity are perfectly balanced and all of this is done without teleology.