Why do E and G both degrade by 1/r^2?

  • Thread starter Thread starter Ghost117
  • Start date Start date
AI Thread Summary
The degradation of electric and gravitational fields at 1/r^2 is primarily due to geometric properties related to the area of a sphere. This behavior is specific to massless mediating particles, as seen in electromagnetism, while forces like the strong and weak nuclear forces, which involve massive mediators, exhibit different decay patterns. The 1/r^2 relationship reflects how fields radiate from a point source in three-dimensional space. In contrast, other fundamental forces do not follow this pattern due to their unique characteristics and the nature of their mediating particles. Overall, the 1/r^2 decay is not universal among all fundamental forces.
Ghost117
Messages
50
Reaction score
3
Both the electric and gravitational fields 'die off' at 1/r^2 ... why?

Is this 1/r^2 value based on a geometric property (area of a sphere) alone? If so, then why don't all the fundamental forces degrade by this same value?

Thanks
 
Physics news on Phys.org
The 1/r^2 is purely due to geometry - if you have any charge or mass distribution other than a sphere or point source, the 1/r^2 goes away and the field is more complicated.
 
Ghost117 said:
If so, then why don't all the fundamental forces degrade by this same value?

can you name one that doesn't ?
 
Then why doesn't the strong force also degrade by 1/r^2 ?
 
Ghost117 said:
Then why doesn't the strong force also degrade by 1/r^2 ?

that's correct, the strong nuclear force and also the weak nuclear force degrade differently
Basically, it is all to do with the mediating particles and if they have mass or not
The strong nuclear force which has the mediator particle as a gluon is only strong at atomic distances.
as is the weak nuclear and its mediator particles the W and Z bosons

EM radiation is mediated by the photon and has no mass and as a result the range of an EM field is infinite

Im not a particle physicist ... I don't want to go any deeper than that :wink:

Dave
 
  • Like
Likes Ghost117
That helps, so it's not just geometry, or more specifically, the geometric reasoning only applies when the mediating particles are mass-less... Thanks.
 
the 1/r^2 thing is basically the way something radiating from a point decreases in a three dimensional space. A line source decreases at 1/r and if we lived in four spatial dimensions instead of three, a point source would decrease as 1/r^3.
 
cosmik debris said:
the 1/r^2 thing is basically the way something radiating from a point decreases in a three dimensional space. A line source decreases at 1/r and if we lived in four spatial dimensions instead of three, a point source would decrease as 1/r^3.

But that's not the complete answer (1/r^2 only applies to 2 of the 4 forces.) See Davenn's response above.
 

Similar threads

I Universal Gravity without Shell Theorem
Replies
13
Views
2K
I A "continous" gravitational field formula r=0 to infinity
Replies
16
Views
652
B Why exactly do we need the gravitational constant?
Replies
11
Views
3K
Electric field of an infinitely long wire with radius R
Replies
5
Views
2K
Electric field at a point inside a non-uniformly charged sphere
Replies
6
Views
1K
Graph of gravitational quantities against distance
Replies
3
Views
3K
A Quadrupole radiation formula for gravity
Replies
3
Views
1K
I In ##\nabla\cdot\vec{E}## why can ##\nabla## pass through the integral?
Replies
8
Views
1K
Pressure versus stress in uniformly charged sphere
Replies
11
Views
1K
Inverse square law of gravitation and force between two spheres
Replies
8
Views
2K

Hot Threads

Recent Insights

Back
Top