- #1

- 50

- 0

## Main Question or Discussion Point

what is the actual equation of e=mc^2? this is only the simplified equation, and i have forgotten the actual one already...

- Thread starter alchemist
- Start date

- #1

- 50

- 0

what is the actual equation of e=mc^2? this is only the simplified equation, and i have forgotten the actual one already...

- #2

chroot

Staff Emeritus

Science Advisor

Gold Member

- 10,226

- 34

You probably mean

E^{2} = p^{2}c^{2} + m^{2}c^{4}

- Warren

E

- Warren

- #3

- 21

- 0

what does the P stand for? and is that equation homogenous?

- #4

chroot

Staff Emeritus

Science Advisor

Gold Member

- 10,226

- 34

- Warren

- #5

- 370

- 0

------

A massist is willing to attribute mass values to anything, in any state of motion. For a massist, this m is really m

E

p = mv

are always true in any inertial frame. For light quanta,

E = pc

p = mc

, because m

So E = mc

------

An energist is willing to attribute energy values to anything, in any state of motion. For an energist, m can only be attributed to something in its rest frame, so the subscript 0 is never needed. For an energist,

p

is always true in any inertial frame. The energy E must come from other physics. For light quanta, p = E/c is a given, so

p

, so

m

. Since c > 0,

m = 0 for a light quantum.

So, E = mc

------

Most modern day physicists, especially high-energy physicists, tend to be energists rather than massists.

- #6

- 370

- 0

I should have said:

- #7

pmb

The equation E = mcOriginally posted by alchemist

what is the actual equation of e=mc^2? this is only the simplified equation, and i have forgotten the actual one already...

www.geocities.com/physics_world/sr/mass_energy_equiv.htm

If the particle is a tardyon (i.e. a particle which travels at speeds less than light) then

m = m

Multiply both sides by c

mc

Substitute in E = mc

E = m

This equation can be rewritten as

E

Pete