Is the Einstein equation E=Mc^2 correct?

Click For Summary

Discussion Overview

The discussion revolves around the validity and application of Einstein's equation E=mc², particularly in the context of nuclear weapons design and the energy yield of atomic bombs. Participants explore theoretical implications, historical instances, and discrepancies in yield calculations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Historical

Main Points Raised

  • Michael questions whether E=mc² was used in the design and testing of atomic bombs and how the energy output was estimated, wondering if all matter was transformed into energy.
  • Some participants reference historical data regarding the mass-energy equivalence in atomic bombs, noting that only a small fraction of mass is converted to energy during fission.
  • There is a claim that E²=(mc²)² + (pc)² applies when mass is not stationary, suggesting that theoretically, all mass could turn into energy.
  • Another participant challenges the idea that all mass turned into energy, arguing that if it had, the destruction would have been much greater than what occurred.
  • One participant calculates a theoretical energy output of approximately 4.68x10¹⁸ J but expresses uncertainty about the actual energy produced.
  • Michael raises a question about the discrepancy in yield calculations for the BRAVO bomb, noting a significant difference between the predicted and actual yields.
  • There is a discussion about the term "p" in the equation, with clarification that it refers to momentum, which is negligible for stationary masses.
  • Participants reference Wikipedia for explanations regarding the high yield of the BRAVO bomb and its causes.

Areas of Agreement / Disagreement

Participants express differing views on the application of E=mc² in nuclear reactions, particularly regarding the extent of mass conversion to energy. There is no consensus on the implications of the equation for the yields of atomic bombs, and the discussion remains unresolved regarding the discrepancies in yield calculations.

Contextual Notes

Limitations include assumptions about mass-energy conversion, the context of nuclear fission processes, and the dependence on specific definitions of terms used in the equations. The discussion also highlights unresolved questions about the accuracy of yield predictions for nuclear tests.

michaelser
Messages
3
Reaction score
0
I wonder if Einstein equation E=mc^2 was used when the A bombes were designed and tested.
How was the output estimated? Was all the matter thransformed into energy, as the equation indicates?
Were there any restrictions to how this equation ( or nny other) was used?
Thanks,
Michael
 
Physics news on Phys.org
from the wiki on mass energy equivalence:

"the "Gadget"-style bomb used in the Trinity test and the bombing of Nagasaki had an explosive yield equivalent to 21 kt of TNT. About 1 kg of the approximately 6.15 kg of plutonium in each of these bombs fissioned into lighter elements totaling almost exactly one gram less, after cooling. The electromagnetic radiation and kinetic energy (thermal and blast energy) released in this explosion carried the missing one gram of mass.[31]"

http://en.wikipedia.org/wiki/Mass–energy_equivalence
 
I believe so, but that only applies when stationary. When the mass is not stationary I believe I'm right in saying E2=(mc2)2 + (pc)2. So yes theoretically all the mass would have turned to energy.
 
CallumC said:
... all the mass would have turned to energy.

What makes you think so? IF all the mass turned into energy, then the formula would apply to all the mass. Do you really think all the mass turned into energy? Had it done so, I think it likely that instead of incinerating a large part of one city, it would have incinerated Japan.
 
phinds said:
What makes you think so? IF all the mass turned into energy, then the formula would apply to all the mass. Do you really think all the mass turned into energy? Had it done so, I think it likely that instead of incinerating a large part of one city, it would have incinerated Japan.

I worked out it should produce about 4.68x1018 J. That's obviously a theoretical value but how much it really produced I don't know. Anyone know what that kind of energy would do?
 
Tony Campillo said:
from the wiki on mass energy equivalence:

"the "Gadget"-style bomb used in the Trinity test and the bombing of Nagasaki had an explosive yield equivalent to 21 kt of TNT. About 1 kg of the approximately 6.15 kg of plutonium in each of these bombs fissioned into lighter elements totaling almost exactly one gram less, after cooling. The electromagnetic radiation and kinetic energy (thermal and blast energy) released in this explosion carried the missing one gram of mass.[31]"

http://en.wikipedia.org/wiki/Mass–energy_equivalence


Thanks for answering so fast.
I don't know much about Gadget style A bombs, but my problem is this: the BRAVO bomb (March 1954) was calculated an yield of 6 Mt(between 4 to 8 Mt). The actual yield was 15 Mt an error/deviation from the original of +150%. How come?
 
CallumC said:
I believe so, but that only applies when stationary. When the mass is not stationary I believe I'm right in saying E2=(mc2)2 + (pc)2. So yes theoretically all the mass would have turned to energy.



Thanks for the reply.
I have a question related to your term of the eqn: (pc)^2. What is the meaning of p.
I assume c is speed of light in "vacuum"
Now some bombs were delivered by airplane. The speed of an airplane is negligible when compared with c.
Therefore the second term is almost zero.
But my real problem is that the BRAVO bomb (March 1954) was calculated an yield of 6 Mt(between 4 to 8 Mt). The actual yield was 15 Mt an error/deviation from the original of +150%. How is this possible?

Thank you much.
 
michaelser said:
Thanks for the reply.
I have a question related to your term of the eqn: (pc)^2. What is the meaning of p.
I assume c is speed of light in "vacuum"
here p is the momentum, which is of course zero for a mass that is at rest.

But my real problem is that the BRAVO bomb (March 1954) was calculated an yield of 6 Mt(between 4 to 8 Mt). The actual yield was 15 Mt an error/deviation from the original of +150%. How is this possible?

There's a pretty decent explanation in wikipedia: http://en.wikipedia.org/wiki/Castle_Bravo#Cause_of_high_yield
 

Similar threads

Undergrad E=mc^2 and acceleration
  • · Replies 26 ·
Replies
26
Views
2K
Undergrad History of E=mc^2 Before Einstein
  • · Replies 28 ·
Replies
28
Views
6K
Undergrad Uncovering a Decent Proof of E=mc^2
  • · Replies 14 ·
Replies
14
Views
3K
Undergrad Discover the Relationship Between Mass and Energy in Electromagnetic Fields
  • · Replies 8 ·
Replies
8
Views
2K
Undergrad Deriving e=mc^2, how is it possible?
  • · Replies 2 ·
Replies
2
Views
1K
Undergrad A problem in the equations for Einstein's Special Theory of Relativity
  • · Replies 8 ·
Replies
8
Views
1K
Graduate Einstein's Definition of Mass: m = E/c^2
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad Was Einstein's Proof of E=MC^2 Flawed?
  • · Replies 7 ·
Replies
7
Views
2K
High School Can you reverse Einstein's famous E=mc^2 equation?
  • · Replies 7 ·
Replies
7
Views
5K
High School Why Isn't Work Equal to Einstein's E=mc²?
  • · Replies 8 ·
Replies
8
Views
2K