Does gravity have a long range?

2 Answers
Jan 17, 2018

The bodies of terrestrial, astronomical and cosmological scale are pretty BIG.


Gravity is dependent on mass, as seen in Newton's universal law of gravitation: #F_(grav)=(Gm_1m_2)/r^2# This equation describes the gravitational force two bodies exert on each other. G is the gravitational constant.

Even as human beings, we are exerting gravitational force between each other, but our mass is so small it is insignificant.

In contrary, at the subatomic level, the weak and strong nuclear forces are very strong.

Jan 17, 2018

Gravity has a long range when large masses are involved.


The strong and weak nuclear forces are very short ranged. They operate at quark level and have no effect beyond adjacent nucleons in an atomic nucleus.

The electromagnetic force has an infinite range. It is also very strong. The force #F# between two charges #q_1# and #q_2# a distance #r# apart is:

#F=1/(4pi epsilon_0)(q_1q_2)/r^2#

Where the Coulomb constant #k_e=1/(4pi epsilon_0)=c^2 times 10^7#

The Coulomb constant is huge, but for the electromagnetic force to be effective at astronomical distances enormous electrical charges would be required. These don't exist in nature.

Gravity also has infinite range. It is also relativity weak because the gravitational constant #G=6.67408 × 10^-11 m^3 kg^-1 s^-2# is very small. Gravity is effective at astronomical distances because the masses involved are huge.

Planets, stars and galaxies have large masses. Newton's equation for the attraction of two masses a distance of #r# apart is:


So, although the value of #G# is small and the value of #r# is large, if the two masses are large enough the force can be considerable.

Gravity is not actually a force. It is a consequence of spacetime being curved by mass. It is hard to curve spacetime. However, masses on an astronomical scale can do this.