Action at a Distance: History & Meaning

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In summary, the concept of action at a distance is still a problem that Newton recognised with his Theory of Gravity, but we now have a better idea of how forces can be transmitted without having to rely on an ether.
  • #1
somy
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Hi all.
I want to know what do they mean by "action at distance". I know the concept of field(!) and the meaning of "space geometry effects". I wanted to know something about the history of this concept.
Thank you.
Somy :smile:
 
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Action at a distance is a problem that Newton recognised with his Theory of Gravity. Simply speaking, how does one mass 'know' that another is near it, and so feel the force? How does the moon 'know' that the Earth is where it is? The same goes for electromagnetic forces.

To get round this problem, the concept of the ether was invented - a substance through with the forces could travel. When this was shown to be wrong in the late 1800s, the idea of a Field came about. However, this didn't solve the problem, it just gave it a name!

We know know about exchange particles that can solve the problem for Eletromagnetic, strong and weak nuclear forces, but for Gravity, there is still a problem, albeit with several proposed solutions.
 
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  • #3
Adrian Baker said:
Action at a distance is a problem that Newton recognised with his Theory of Gravity. Simply speaking, how does one mass 'know' that another is near it, and so feel the force? How does the moon 'know' that the Earth is where it is? The same goes for electromagnetic forces.

To get round this problem, the concept of the ether was invented - a substance through with the forces could travel. When this was shown to be wrong in the late 1800s, the idea of a Field came about. However, this didn't solve the problem, it just gave it a name!

We know know about exchange particles that can solve the problem for Eletromagnetic, strong and weak nuclear forces, but for Gravity, there is still a problem, albeit with several proposed solutions.


I think that Einstein GR does not solve the problem of gravitation. In fact one is substituting the old query

"How does the moon 'know' that the Earth is where it is?"

by modern one

How does the moon 'know' that the curvature of spacetime is where it is?

In the same form that Newton equation just compute force and don't answer the mechanism for it. Einstein field equations just compute spacetime curvature (if any) and don't answer the mechanism for it.

Regarding the supposed success explaining of electromagentic force by means of interchange of particles, one may be highly eskeptic.

- The explaining reliy on many asumptions and unobserved facts (virtual particles are newer seen)

- The explaining only work for asymptotic states for free particles. There is not convincing explaining for bounded states.

- The asumption of interchange of particles is inspired in classical EM field theory with retarded LW potentials. It is known that LW retarded potentials are not good enough, by this reason Feynman looked for the use of advanced potentials also.


Action at a distance is more convincing than field theory.
 

1. What is action at a distance?

Action at a distance is a phenomenon in physics where objects can affect each other without any physical contact or intermediary medium. This concept challenges the traditional notion of causality and has been a subject of debate among scientists for centuries.

2. How was the concept of action at a distance discovered?

The concept of action at a distance was first introduced by the English physicist Isaac Newton in the 17th century. He observed that objects can exert a force on each other even when they are not in direct contact, such as the gravitational pull between celestial bodies.

3. What are some examples of action at a distance?

Some commonly cited examples of action at a distance include gravity, magnetic and electrical forces, and even psychic phenomena. These forces act over a distance without any physical connection between the objects involved.

4. How does action at a distance relate to modern physics?

The concept of action at a distance has been further explored and refined by modern physics, especially in the fields of quantum mechanics and relativity. These theories provide explanations for the underlying mechanisms behind this phenomenon, such as the exchange of particles or the warping of space-time.

5. What is the significance of action at a distance in our understanding of the universe?

The concept of action at a distance has played a crucial role in shaping our understanding of the natural world and the laws that govern it. It has also led to advancements in technology, such as in the development of wireless communication and remote control devices.

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