Why heat, light, and waves all follow the inverse square law?

Click For Summary

Discussion Overview

The discussion revolves around the question of why heat, light, and waves all follow the inverse square law, exploring the underlying principles and potential connections between different physical phenomena. Participants examine the implications of dimensionality, conservation laws, and the geometry of space in relation to this law.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that the inverse square law is a consequence of the spherical nature of phenomena in three-dimensional space, where a spherical shell with twice the radius has four times the area.
  • Another participant agrees with the previous point but adds that all phenomena obeying the inverse square law are products of the same force, prompting a request for clarification on what that force is.
  • A participant introduces a practical analogy involving a "butter gun" to illustrate how uniform spreading results in a 1/r² relationship.
  • It is noted that while many phenomena follow the inverse square law, radio waves exhibit a field strength that decreases as 1/R, indicating that not all spreading behaviors conform to the same law.
  • One participant questions the implications of multiple forces, suggesting that differences in strength or density do not necessarily prove the existence of more than one type of force.

Areas of Agreement / Disagreement

Participants express various viewpoints on the relationship between the inverse square law and conservation laws, with some agreeing on the geometric reasoning while others challenge the notion of a singular force connecting all phenomena. The discussion remains unresolved regarding the nature of forces and the applicability of the inverse square law across different contexts.

Contextual Notes

Participants acknowledge that the discussion involves complex relationships between geometry, conservation laws, and the behavior of different types of waves and forces, with some assumptions and definitions left unaddressed.

Mattius_
Messages
8
Reaction score
0
Why is it that heat, light, and waves all follow the inverse square law? Why not the inverse cube law? why any law? why doesn't light radiate to 100% of its horizon instead of expanding by mathematical functions?

The best explanation i can come up with is that the inverse square law is a function of the spherical nature of things... Am i anywhere near the solution?
 
Science news on Phys.org
You're very near the solution

in three space dimensions that is the way that conserved things spread out. A spherical shell with twice the radius has four times the area.
 
Tyger is correct in as far as he goes, it could be added that all obey the inverse square law because they are all t[products of the same force.
 
elas:
Tyger is correct in as far as he goes, it could be added that all obey the inverse square law because they are all t[products of the same force.

Do you have any evidence for that? What force do you mean? I see no reason to believe that there is any connection than that they are all examples of (different) conservation laws.


When I was in high school my physics teacher had what he called a "butter gun". It was simply a squirt gun with a dowel frame coming from the muzzle. There were dowels forming a square frame at a certain distance and dowels forming 4 identical squares at twice that distance. The point was that, since area is dependent upon length squared (and "similar triangles" tells us that, twice the distance from the end of the gun, the width is twice as great) we could fit 4 "pieces of toast" at twice the distance as that at which we could fit 1. Since the "amount of butter" was fixed, at twice the distance each piece of toast got 1/4 the toast as a piece at the first position.

Anything that "spreads out" uniformly must obey a "1/r2" law.
 
Originally posted by Tyger
in three space dimensions that is the way that conserved things spread out. A spherical shell with twice the radius has four times the area.

Originally posted by HallsofIvy
...they are all examples of (different) conservation laws.

In a very real sense, you guys are both right. Tyger argued in terms of spacetime geometry while HallsofIvy in terms of conservation laws. Well there's a theorem of profound and fundamental importance in physics due to emmy noether that relates conservation laws and symmetries. In this case it's the relation between poincare symmetry of spacetime geometry and the laws of conservation of mass energy-momentum it gives rise to.
 
But not everything

spreads out that way. The field strength of a radio wave goes as 1/R, which is why they can be received over such a large distance. But field strength is related to an amplitude and not a probability. The probability that something will absorb a photon from the wave still goes as R−2.
 
If the same law applies to all forces then what is the difference between forces?
Your reply will probably be that it is a difference in strength or density, or both.
To which I would reply that neither is proof that there is more than on kind of force (operating at different densities).
I would like to have a definition that demonstrates the need for more than one force.
 

Similar threads

  • · Replies 2 ·
Replies
2
Views
6K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 33 ·
2
Replies
33
Views
4K
  • · Replies 10 ·
Replies
10
Views
4K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 2 ·
Replies
2
Views
5K
  • · Replies 5 ·
Replies
5
Views
2K