How is E=mc^2 connected to the speed of light?

  • Thread starter Thread starter DeadCat_86
  • Start date Start date
DeadCat_86
Messages
2
Reaction score
0
In the mass-energy equivalent equation, E=mc^2, why is it related to the speed of light?
 
Physics news on Phys.org
That is the formula for rest energy predicted by Special Relativity.

From the postulates of SR (Invariance of c, physical laws are the same in all inertial frames) one can derive the equations describing energy:
E_{tot}=\gamma mc^2
E_k=(\gamma -1)mc^2
which lead to the conclusion that a mass has a rest energy E_0=mc^2 which is called the mass-energy equivalence.

So the the short answer is that it follows from the postulates of SR.

For a more in depth description detailing how the equation is derived, see
http://en.wikipedia.org/wiki/Mass-energy_equivalence#Background
 
Merry Christmas!

DeadCat_86 said:
In the mass-energy equivalent equation, E=mc^2, why is it related to the speed of light?

He DeadCat_86! Have a bouncy Christmas! :smile:

e is energy, which is ML2/T2, while m is of course just M,

so the conversion factor must have dimensions of L2/T2, ie it has to be a velocity squared …

and c is the only non-arbitrary velocity for such a general equation! :wink:
 
  • Like
Likes zdroide


tiny-tim said:
He DeadCat_86! Have a bouncy Christmas! :smile:

e is energy, which is ML2/T2, while m is of course just M,

so the conversion factor must have dimensions of L2/T2, ie it has to be a velocity squared …

and c is the only non-arbitrary velocity for such a general equation! :wink:

Dimensional analysis saves the day yet again!
 

Thread 'I don't see how a black hole's event horizon can be crossed'

OK, so this has bugged me for a while about the equivalence principle and the black hole information paradox. If black holes "evaporate" via Hawking radiation, then they cannot exist forever. So, from my external perspective, watching the person fall in, they slow down, freeze, and redshift to "nothing," but never cross the event horizon. Does the equivalence principle say my perspective is valid? If it does, is it possible that that person really never crossed the event horizon? The...
View full post »

Thread 'Synchronizing clocks in an inertial frame if light is anisotropic'

ASSUMPTIONS 1. Two identical clocks A and B in the same inertial frame are stationary relative to each other a fixed distance L apart. Time passes at the same rate for both. 2. Both clocks are able to send/receive light signals and to write/read the send/receive times into signals. 3. The speed of light is anisotropic. METHOD 1. At time t[A1] and time t[B1], clock A sends a light signal to clock B. The clock B time is unknown to A. 2. Clock B receives the signal from A at time t[B2] and...
View full post »

Thread 'Question about Parallel Transport'

In this video I can see a person walking around lines of curvature on a sphere with an arrow strapped to his waist. His task is to keep the arrow pointed in the same direction How does he do this ? Does he use a reference point like the stars? (that only move very slowly) If that is how he keeps the arrow pointing in the same direction, is that equivalent to saying that he orients the arrow wrt the 3d space that the sphere is embedded in? So ,although one refers to intrinsic curvature...
View full post »

Similar threads

I E=mc^2 and acceleration
Replies
26
Views
2K
I Deriving e=mc^2, how is it possible?
Replies
2
Views
1K
B Is E=mc² the Formula for the Speed of Light?
Replies
17
Views
2K
I Uncovering a Decent Proof of E=mc^2
Replies
14
Views
2K
B Photon Energy Without Rest Mass – How?
Replies
17
Views
2K
I Discover the Relationship Between Mass and Energy in Electromagnetic Fields
Replies
8
Views
2K
I Best Derivation of E=mc^2 - Fdx = V^2 dm
Replies
17
Views
2K
B How does hawking radiation escape a black hole?
Replies
11
Views
2K
I Does Special Relativity Affect Mass?
Replies
1
Views
994
B What is m in Kinetic Energy? Relativistic mass or Rest mass?
2
Replies
55
Views
6K

Hot Threads

Recent Insights

Back
Top