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First, please tell me if following logic and assumptions are correct. The 4 forces of the universe generate all the changes in velocity of particles in the universe. The particles in the universe behave in such a way that entropy increases over time. Therefore, the 4 forces of the universe increase entropy.

But that raises the following questions for me. Had electromagnetism attracted like charges and repelled opposite charges, would the entropy of the universe decrease over time? Had gravity repelled objects of mass instead of attracting them, would entropy decrease over time?

If this is indeed the case that the opposite of the forces would decrease entropy, why would it so happen that every force happens to increase entropy? Is the increase in entropy itself the fundamental aspect of the universe and the forces fall in line with that or is something more subtle going on?

Thanks.

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Systems do not need forces or interactions in order to have their entropy increase. The prototypical example of a low entropy system is a box where all the gas has been compressed into one corner. You release the gas, and the gas spreads out through the box. You don't need the gas particles to interact with anything in order for this to happen.

"Had electromagnetism attracted like charges and repelled opposite charges, would the entropy of the universe decrease over time?"

No.

The entropy of a state is defined in terms of the total energy of the state (or some other macroscopic quantity), and how many other states there are with the same energy for a given system. Changing the nature of the forces would change the energy landscape of any given system, but would not change their tendency to find states of high multiplicity.

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I will try this in laymen's language.

Energy has a tendency to move. When it moves alone (EM or gravitational waves), it moves at c. When it moves matter, it moves per KE = 1/2 * m * v * v. The entropy is increased because of this property of energy - i.e. tendency to move. This tendency to move results into loss of energy from a system, and also results into disorder into a system. As long as KE (not rest mass/energy) is inside the system, it causes disorder in the form of KE. When it escapes the system, it is lost and entropy increases. So, the forces enable conversion of energy into KE, or waves, loss of which which eventually results in increased entropy.

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