### Do all the objects in the universe exert force on all other objects?

• Timtech

8 years ago

Do all the objects in the universe exert force on all other objects? Like a type of gravity; also, how much does it decrease as it gets farther away? Curious about your thinking behind the wording "like a type of gravity". Are you seeking a force with infinite reach other than gravity? The responses given so far have a distinctly "Newtonian" flavour. The appropriate gravitational theory for this question is of course Einstein's and from that we learn that everything within our causal horizon effects us gravitationally. Whether material beyond our causal horizon can have influence is technically far more complex and depends on a number of assumptions about the initial conditions for the cosmic expansion. Anyone care to address that? Anybody that thinks they can answer this question needs to think back to the days before we knew of the existence of dark energy and dark matter. We detect things (including those mentioned above) by the effect (force) they have on other things. If there was an object in space not exerting any force on another object, we wouldn't know that it is there. Also, the only known "free" mass-less particle (now that the neutrino is thought to have mass) is the photon which does exert a "force" in the sense that it has momentum p = h/(wavelength). This is what "pushes" solar sails (radiation pressure). Particles with mass, of course, "exert" gravity. One more thing. We only know of 4 forces. The strong and weak forces fall off with distance so quickly (short lifetime of particles that carry the force) that they are confined to distances around the size of a nucleus. The other two we know well (electromagnetism and gravity). There is no "kind of like gravity" force as far as we know.

• 8 years ago

Yes - this is the formula:

$$F = G\frac{m_1m_2}{d^2}$$

Using this equation, we can say that all atoms in the universe exert force upon eachother. One carbon-12 atom has a mass of $1.660538921(73)\times10^{-27} kg$. That's a crazy small mass.

Now let's say that these two atoms are 100,000,000 light years apart. That's $9.461\times10^{23} m$, which is a very long distance.

Now, if we plug these values into our equation, we get that the force is: $1.709191430132 \times 10^{-59} N$

That's a very, very small amount of force. But it's still force.