Solve E=mc2 Condundrum: Views on Logic & Reasoning

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Discussion Overview

The discussion revolves around the interpretation and application of the equation E=mc², exploring its implications in the context of gravitational potential energy and the concept of a "space lever." Participants examine the validity of various reasoning approaches and calculations related to energy, mass, and gravitational forces.

Discussion Character

  • Debate/contested
  • Exploratory
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant proposes a calculation involving gravitational force and distance to equate it to the speed of light squared, questioning the validity of their reasoning.
  • Another participant asserts that the potential energy expression for gravitational energy is only valid near the Earth's surface, indicating limitations in the initial approach.
  • A later reply clarifies that while the calculation may be valid in Newtonian physics, it lacks meaning in that context, and the derivation is not particularly interesting in relativistic physics.
  • One participant suggests that the Hamiltonian formulation is more appropriate for discussing energy in relativistic contexts, referencing the conserved quantity and kinetic terms.
  • Another participant challenges the coherence of the original reasoning, stating it is nonsensical and lacking logical structure.
  • Concerns are raised about the misuse of units and the need for identifiable relations between variables in physical scenarios.

Areas of Agreement / Disagreement

Participants express significant disagreement regarding the validity of the original reasoning and calculations. There is no consensus on the interpretation of the concepts discussed, with some participants finding the arguments nonsensical while others attempt to clarify or refine the ideas presented.

Contextual Notes

Limitations include the dependence on specific definitions of energy and force, as well as the unresolved nature of the calculations presented. The discussion highlights the complexities involved in transitioning from Newtonian to relativistic frameworks.

JSHD2019
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TL;DR
Can you cancel the masses out by turning E = mc2 into a space lever?
E = mc2 : kg.m2/s2 ≡ kg.m.m/s2 ≡ kg.m.a ≡ m.N ≡ Nm ≡ j as requ'd
Thence,
Distance x F = m.C2
Distance x Acceleration = C2
For a rest mass likely only Force acting is due to Gravity so:
Distance x 9.81 = C2
Distance = 9.161e+15 meters

Can you do the above or is the reasoning non valid and illogical? Your views
 
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Hello JSHD, ##\qquad## :welcome: ##\qquad## !

Can't do, I 'm afraid :smile: :

  • The potential energy expression for the potential energy from gravity , ## mgh## is only valid in the neighborhood of the surface of the Earth (##g## has to be constant).

  • ##E=mc^2## is in fact ##E=\gamma m_0 c^2## where ##m_0## is the rest mass (-- the one you use for ##mgh## )

And a few more issues ...

But keep the questions coming !

##\ ##
 
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JSHD2019 said:
For a rest mass likely only Force acting is due to Gravity so:
Distance x 9.81 = C2

Can you do the above or is the reasoning non valid and illogical?
You can't do that.
 
ok if not a lever how about a wavelength so e.g.

1 light year = 9.461e+15 m (look a bit like any other numbers you've seen recently?)
f = C/ λ
f = 3.16871851e-8
T = 31558499.0467 / 3600
= 8766.249725 / 24
= 365 days
 
You are calculating the distance you need to raise a mass ##m## in a uniform gravitational field in order for the change in gravitational potential energy to be equal to the rest mass energy of the mass.

In Newtonian physics this calculation is perfectly valid, but meaningless since "rest mass energy" isn't a concept in Newtonian physics.

In relativistic physics there are circumstances where the calculation is approximately meaningful (although your derivation via gravitational force isn't really), but it's not particularly interesting nor a general case. It's certainly nothing to do with a "space lever", whatever that may be. You are just calculating a weak-field approximation to the height difference needed for the gravitational potential change to hit a certain threshold in a particular gravitational field.
 
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I think in terms of the Hamiltonian (away from the classic Legrangian 1/2m.v2) actually as first posted the γm0c2 is very much more appropriate so thank you. Thence the conserved quantity H= v.p - L = γm0c2 = E; so E = γm0c2 becomes the kinetic term in the Lagrangian (Precision Cosmology). Am I still mixing apples and pears as the Americans say
 
JSHD2019 said:
Can you do the above or is the reasoning non valid and illogical? Your views
It is complete and utter nonsense.
 
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JSHD2019 said:
Summary: Can you cancel the masses out by turning E = mc2 into a space lever?
What is a space lever? Please provide a professional scientific reference, like a peer reviewed paper or a textbook that describes the term.

JSHD2019 said:
Distance x F = m.C2
Work is force times distance, not energy. Energy and work are different. They have the same units but they are not the same thing. You cannot simply substitute two quantities because they have the same units.

JSHD2019 said:
Distance x Acceleration = C2
The original formula, ##E=mc^2##, applies for a mass at rest. So which distance and what acceleration are you talking about?

JSHD2019 said:
For a rest mass likely only Force acting is due to Gravity
Gravity is not a force in relativity.

JSHD2019 said:
Can you do the above or is the reasoning non valid and illogical? Your views
Very non valid and extremely illogical.

You seem to just be throwing around units for no purpose and seeing if something sticks. That is not logical. For each formula, you need to identify the variables with something specific in a given scenario that you are analyzing. It can be a fairly general scenario, but each variable must have an identifiable relation to a physical quantity.

There is nothing to be gained by further discussion of this incoherent assemblage of random quantities. This thread is closed.
 

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