c in E=mc^2

[steevey]

Someone is trying to tell me that when I use c in E=mc^2 that I am using time because c is light going 186,000 miles per second. However, I said its just a value equivalent to 186,000^2, and there isn't even a such speed as 300,000,000miles/s, so could someone clear this up? Does time have to pass in order for the relationship of E=mc^2 to be true? Do you need to travel at the speed of light or whatever using time in that would be?

Edited February 16, 2011 by steevey

[lemur]

Isn't energy a time-based attribute? Isn't it something like power over time? Sorry for being vague; I just wanted to move this thread along some.

[steevey]

Isn't energy a time-based attribute? Isn't it something like power over time? Sorry for being vague; I just wanted to move this thread along some.

 

But in that cause you'd have time in multiple expressions of an equation of which you solve for time, which physicists say you can't define time since it isn't physical so no field work can be done on it or if it is space itself, there is no physical evidence or proof for anything that comprises the fabric of spacetime.

 

Also, I think energy is just the ability to do work, and since mass is equal to energy at any moment regardless of what time it is anywhere, I don't see why time should matter. Even if your by a block hole where time is said to be slowed down, mass still has a specific amount of energy its equal to.

Edited February 16, 2011 by steevey

[lemur]

But in that cause you'd have time in multiple expressions of an equation of which you solve for time, which physicists say you can't define time since it isn't physical so no field work can be done on it or if it is space itself, there is no physical evidence or proof for anything that comprises the fabric of spacetime.

Time and distance can be used as dimensional variables regardless of the ontological status of "time" and "space" as transcendent phenomena, can't they?

 

Also, I think energy is just the ability to do work, and since mass is equal to energy at any moment regardless of what time it is anywhere, I don't see why time should matter. Even if your by a block hole where time is said to be slowed down, mass still has a specific amount of energy its equal to.

So what you're saying is that since work is force across a distance, energy should be able to be limited to force and distance without time? But force itself is described in terms of acceleration, which involves time in terms of distance-change (speed) as well as in terms of speed-change (acceleration).

 

Regarding E=MC^2, I have read many people say that it is simply a consolidated formula derived from other equations and that the units cancel out when using it to calculate the amount of energy contained in a given amount of mass. I'd jumble the math or I'd provide an example.

 

 

 

 

 

[steevey]

Time and distance can be used as dimensional variables regardless of the ontological status of "time" and "space" as transcendent phenomena, can't they?

 

 

So what you're saying is that since work is force across a distance, energy should be able to be limited to force and distance without time? But force itself is described in terms of acceleration, which involves time in terms of distance-change (speed) as well as in terms of speed-change (acceleration).

 

Regarding E=MC^2, I have read many people say that it is simply a consolidated formula derived from other equations and that the units cancel out when using it to calculate the amount of energy contained in a given amount of mass. I'd jumble the math or I'd provide an example.

 

 

 

 

 

 

Distance is physical, since there is physical distance separating objects, but time, I don't get why only an assortment of batteries and wires should be able to see time unless time is just a periodic measurement than humans created. And I guess a force like gravity is described in terms of time but only when calculating the speed of a free-falling object. If I'm standing on the ground, I'm not going anywhere so theres no need to calculate my acceleration over time.

Can you give me an example of where the unites cancel out?

[Klaynos]

Time for dimensional analysis!!!

 

E = mc^2

 

m = mass

 

c = length / time

 

E = mass * length^2 / time^2

 

Looks to be time in there....

 

So let us look at something a bit more usual to us, kinetic energy..

 

E = 1/2 mv^2

 

1/2 is dimentionless

 

m = mass

 

v = length / time

 

E = mass * length^2 / time^2

 

...

[lemur]

Distance is physical, since there is physical distance separating objects, but time, I don't get why only an assortment of batteries and wires should be able to see time unless time is just a periodic measurement than humans created. And I guess a force like gravity is described in terms of time but only when calculating the speed of a free-falling object. If I'm standing on the ground, I'm not going anywhere so theres no need to calculate my acceleration over time.

Can you give me an example of where the unites cancel out?

Sorry I can't remember the specifics about the units canceling, but you might try to look up old threads about converting mass to energy (I may be thinking of another forum, though).

 

I don't see why so many people get hung up on the idea that time and space have to be things independent from duration and volume measurements. It is a philosophical issue to ask why durations and volumes display regularities across divergent phenomena. Clocks don't have to measure something outside themselves because they can function just fine by running according to their own mechanics. Likewise, the physical force-fields that make up matter don't need collusion from some abstract container called "space" to assert volume, do they? Either way, these are philosophical issues that always seem to cause problems so I don't know how much value there is in pursuing them here. I'll be happy to PM on the subject with you, though, if you like.

[steevey]

Time for dimensional analysis!!!

 

E = mc^2

 

m = mass

 

c = length / time

 

E = mass * length^2 / time^2

 

Looks to be time in there....

 

So let us look at something a bit more usual to us, kinetic energy..

 

E = 1/2 mv^2

 

1/2 is dimentionless

 

m = mass

 

v = length / time

 

E = mass * length^2 / time^2

 

...

 

So in other words, the process of energy equaling or becoming energy takes time which is why time is needed, but the fact that the relationship is true is regardless of time since that relationship is always there? I mean I could be standing near a black hole which is said to slow down time and yet the same amount of mass on Earth would equal the same amount of energy there as it did by the black hole.

Edited February 16, 2011 by steevey

[michel123456]

I don't know about black holes. Why do we always have to discuss those things?

 

The equation means that space & time are factors that transform mass into energy. Or that mass embedded in spacetime corresponds to a certain amount of energy.

 

Time is in it.

 

What the equation doesn't say is what is mass that is not embedded in spacetime.

[mississippichem]

So in other words, the process of energy equaling or becoming energy takes time which is why time is needed, but the fact that the relationship is true is regardless of time since that relationship is always there? I mean I could be standing near a black hole which is said to slow down time and yet the same amount of mass on Earth would equal the same amount of energy there as it did by the black hole.

 

This is just [math] E = mc^{2} [/math] "re-expressed" in SI units:

 

[math] 1J=1kg \cdot \frac{1 m^{2}}{1 s^{2}} [/math]

 

This is the definition of the joule which is the SI unit for energy:

 

[math] 1J =1 \frac{kg \cdot m^{2}}{s^{2}} [/math]

 

This is basically what Klaynos showed a few posts ago, but I'm just expressing it in explicit units to show how it works.

 

See the similarity? Don't think too hard here, you'll get confused. This is a case of the math making things easier.

Edited February 16, 2011 by mississippichem