E=mc2 How did Einstein get to this equation?

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Discussion Overview

The discussion centers around the derivation and significance of Einstein's equation E=mc², exploring the mathematical reasoning behind it and questioning why this formulation is preferred over alternatives like F=mc². Participants express curiosity about the historical context and the conceptual implications of the equation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions the reasoning behind E=mc² versus F=mc², suggesting that force could be derived from mass and c².
  • Another participant provides links to historical resources, including Einstein's original paper, and emphasizes that there are multiple ways to arrive at the equation.
  • Some participants caution against learning relativity solely through forum discussions, recommending structured books for better understanding.
  • A later reply challenges the idea of using F=mc², stating that it does not make sense due to the mismatch of units between energy and force, and clarifies that E=mc² relates to the inherent energy of an object at rest.

Areas of Agreement / Disagreement

Participants express differing views on the formulation of the equation and the appropriateness of using F=mc². There is no consensus on the best approach to understanding the equation or its derivation.

Contextual Notes

Some limitations are noted regarding the depth of understanding that can be gained from informal discussions, as well as the potential for confusion when comparing different physical concepts like energy and force.

Who May Find This Useful

This discussion may be of interest to those exploring the fundamentals of relativity, the historical context of Einstein's work, and the conceptual understanding of energy and mass in physics.

Zac Einstein
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How did Einstein get to this equation?...I mean the math behind it and why E=mc2? why not F=mc2? we can get so much force from m*c2 right? but why did Einstein write E=mc2? :smile:
 
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Here is Einstein's original paper on the topic, which is actually pretty readable: http://fourmilab.ch/etexts/einstein/E_mc2/www/

Of course there's no particular reason that we have to go about things exactly the same way as Einstein. There are various ways of getting this result.

In general, you're not well advised to try to learn relativity from scratch simply by posting questions on this forum. You need a book to present things in an organized way. Some good books about special relativity are (from easiest to hardest):

Takeuchi, An Illustrated Guide to Relativity
Mermin, It's About Time: Understanding Einstein's Relativity
Taylor and Wheeler, Spacetime Physics

The advantage of Takeuchi and Mermin is that they require very little background in math or physics. Their disadvantage is a total lack of connection to experiment.
 
bcrowell said:
Here is Einstein's original paper on the topic, which is actually pretty readable: http://fourmilab.ch/etexts/einstein/E_mc2/www/

Of course there's no particular reason that we have to go about things exactly the same way as Einstein. There are various ways of getting this result.

In general, you're not well advised to try to learn relativity from scratch simply by posting questions on this forum. You need a book to present things in an organized way. Some good books about special relativity are (from easiest to hardest):

Takeuchi, An Illustrated Guide to Relativity
Mermin, It's About Time: Understanding Einstein's Relativity
Taylor and Wheeler, Spacetime Physics

The advantage of Takeuchi and Mermin is that they require very little background in math or physics. Their disadvantage is a total lack of connection to experiment.


You're right sir :smile:
I want to know everything but not in an organized way :smile:
Thank you :rolleyes:
 
Zac Einstein said:
How did Einstein get to this equation?...I mean the math behind it and why E=mc2? why not F=mc2? we can get so much force from m*c2 right? but why did Einstein write E=mc2? :smile:

By the way, F = mc^2 makes no sense. The right hand side is a unit of energy, the left is a unit of force. In fact, once you read up on it a little, you'll see that E = mc^2 applies to an object just sitting there - it has an inherent energy associated with it just by existing. Talking about forces in that context is like asking how much speed I can get out of a car that has no wheels.
 

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