Info on E= MC 2

[Queztacotl]

In the formula E=MC2, what does the E stand for, is it energy?

 

What do you put in place for each of the letters, for example you put the speed of light for C, but what and what can you put in for E and M?

 

How can Mass be a form of energy?

Is it not a name for the total amount of matter in a substance????? I don't know!

[skuinders]

E = energy (joules)

m = mass (kg)

c = speed of light (m/s)

 

I'll let a physicist explain the rest.

[infamous]

 

How can Mass be a form of energy?

!

 

You will most likely get more than one answer to this question because theorists view the answer in several different ways. My own personal description for matter would be:

 

Localized Orbital Energy Flux

 

Localized because, matter can take up space and have weight.

Orbital because, particles of matter can be understood as energy spinning in place.

Energy Flux because, flux is a term to define moving from one place to another.

[adjective]

Mass isn't a form of energy. Matter is. Mass is a measure of the amount of matter we have. If m meant matter in E = mc^2, what would the equation mean? We can try using only units in the equation to figure this out.

 

Mass is in kilograms, c is in meters per second. So, we substitute the labels for the variables:

 

kg * (m/s)^2 == kg * m^2/s^2 == kg * m^2 * s^-2 == j or joules, which is a measure of energy

 

One the other hand, we could use matter. Matter has no label, so we simply have m/s to work with

 

(m/s)^2 == m^2 * s^-2 == I have no idea what that labels.

 

It would not yield any meaningful. It's the same way with c--we call it the speed of light. Speed is a measure of how much distance something covers in a given amount of time.

 

So, in order to come up with anything that's useful, we use measurements. Mass, in a sense, is simply labelled matter.

[infamous]

Mass isn't a form of energy. Matter is..

 

This is absolutely true, my statements were misleading. When Queztacotl asked "How can mass be a form of energy", I assumed he was talking about matter. Both energy and matter have mass, but neither energy or matter are mass. I stand corrected. However:

If you read my post carefully you will notice that I was defining matter and not mass.

[EWright]

I'm glad someone posted this, as I have questions regarding this as well. Can someone better explain why c is squared? If c represents the speed of light and nothing can travel faster than light, how is squaring this speed factor relevant?

 

Yes, I do understand that this demonstrates my lack of a full understanding of SR, but I acknowledge this and that is why I am asking.

 

Also, can I assume that E=MC^2 is the same as E=M(m/s)^2? And then does this mean that Energy is the equivalent of the mass of an object moving at the speed of light in two dimensions? And if so, I assume it is impossible to fully utilize the energy of an object because we can't reach light speed; but rather, the more speed something achieves, the more Energy is given off? Proof of this equation is often attributed atomic bombs. Does this then mean as the materials of the bombs were accelerated via an explosion, the achieved or gave off the energy needed to cause such substantial damage? In other words, does E = an increase in the travel time of mass per unit of length measurement? :xx:

 

I may be way off base on this, as I am just pondering these questions as I read this post so you're getting the raw thought process, rather than a more educated guess. A description of how this formula corresponds to my understanding or lack there of, would be very much appreciated.

 

Thanks.

[adjective]

After this question I went and looked around and the answer I found was that m^2/s^2 has no intrinsic meaning. Like pi, there is no physical significance whatsoever. When taken as a whole equation, obviously, the unit yielded is the joule--which is a measure of energy. So c^2 has absolutely no physical analog. In truth, it's something of an artifact of the derivation.

 

The atomic bomb demonstrates this equation not because of the speed of the explosion or anything, but rather if you were to gather up all the products produced by the fission or fusion reaction and massed them, the mass would be less after the explosion than before. This, if I recall correctly, is because of the breaking of the strong nuclear force in a fission reaction. In a fission reaction, an atom basically breaks into two pieces and releases some neutrons, photons, and energy. The energy is from the nucleus breaking apart. There's obviously something holding the neutrons and protons together--which is called the strong nuclear force--and some of that gets released by breaking an atom apart.

 

The fact that mass is lost in this process gives rise to the posulate that energy and matter are the same thing. Photons are massless, as, in theory, would be energy. However, since these are the only things being lost, why is mass disappearing? Thus, energy and matter are two sides of the same coin.

 

The inability to get perfect conversion from matter to energy doesn't deal with our inability to accelerate something to light speed--it's because the only way to destroy matter (at least to my knowledge) is antimatter. Antimatter is very expensive and difficult to produce, so we end up expending more energy to create antimatter than can be produced by the collision of antimatter and matter.

[Little Bang]

You are correct the only reaction that fits E = MCC is a matter antimatter collision. This is just a guess but I think the atomic bomb gave only something like a 5 to 10% conversion rate.

 

BTW Ewright, E does not equal M(m/s)^2

[EWright]

BTW Ewright, E does not equal M(m/s)^2

 

So c = m/s but c^2 does not equal m^2/s^2? Why not?

[tarak]

There was a story that in the first decade of last century only two people other than Einstein understood the relativity theory.I am unable to recall it.

[adjective]

c^2 == m^2/s^2 (in terms of labels) but that label is physically meaningless and, as such, not worth dwelling on. I'm not exactly sure what Little Bang meant by his response--perhaps you'd care to clarify Little Bang?

 

I believe the anecdote you're trying to recall, tarak, is this one:

 

Shortly after relativity was released, it was hard for most scientists to understand what exactly it said. It was rumored that only three people on earth understood it. When Arthur Eddington was asked if this was true, that only three people understood it, he paused and replied, "I'm trying to think of who the third person is."

[EWright]

c^2 == m^2/s^2 (in terms of labels) but that label is physically meaningless and, as such, not worth dwelling on. I'm not exactly sure what Little Bang meant by his response--perhaps you'd care to clarify Little Bang?

 

I believe the anecdote you're trying to recall, tarak, is this one:

 

Shortly after relativity was released, it was hard for most scientists to understand what exactly it said. It was rumored that only three people on earth understood it. When Arthur Eddington was asked if this was true, that only three people understood it, he paused and replied, "I'm trying to think of who the third person is."

 

How can you say that c^2 is meaningless? Or are you saying only (m/s)^2 is meaningless? And if they're equivalent, what's the difference? And how can you say a variable used in the most pronouned equation of all time is meaningless? What exactly DOES c^2 mean please?

[adjective]

*blink*

 

I explained this previously.

 

The label m^2/s^2 is physically meaningless. It has no bearing on reality. kg*m^2/s^2 does. This really isn't so amazing.

 

Equations of equal importance have similar properties. C = 2PIr. E = (1/2)mv^2. PI has no intrinsic meaning, it simply ends up there and makes it work--we can figure out how it makes it work, but we can't say that it has a meaning apart from its use in equations. And if you try to argue that it's the ratio of a circle's circumference to its diameter, so it makes sense to see it there, there are plenty of equations where PI pops up out of nowhere and just is simply there (such as the probability density function). Same with the constant e. In the second equation, the equation for kinetic energy under Newtonian mechanics, the same problem occurs with labels as in E = mc^2.

 

There is nowhere where a squared velocity exists on its own in physics. There are, however, several places where it exists with other supporting players (e.g. E = mc^2, E = (1/2)mv^2, W = N*m/s). A word is composed of letters, but none of those letters has intrinsic meaning.

[Qfwfq]

Mass isn't a form of energy. Matter is. Mass is a measure of the amount of matter we have.

:xx:

Mass means rest energy. Before SR it meant the measure of the amount of matter, but now it has become just a synonym for rest energy. It also shouldn't be confused with the total energy, which increases with a free body's velocity.

[EWright]

*blink*

 

I explained this previously.

 

The label m^2/s^2 is physically meaningless. It has no bearing on reality. kg*m^2/s^2 does. This really isn't so amazing.

 

Equations of equal importance have similar properties. C = 2PIr. E = (1/2)mv^2. PI has no intrinsic meaning, it simply ends up there and makes it work--we can figure out how it makes it work, but we can't say that it has a meaning apart from its use in equations. And if you try to argue that it's the ratio of a circle's circumference to its diameter, so it makes sense to see it there, there are plenty of equations where PI pops up out of nowhere and just is simply there (such as the probability density function). Same with the constant e. In the second equation, the equation for kinetic energy under Newtonian mechanics, the same problem occurs with labels as in E = mc^2.

 

There is nowhere where a squared velocity exists on its own in physics. There are, however, several places where it exists with other supporting players (e.g. E = mc^2, E = (1/2)mv^2, W = N*m/s). A word is composed of letters, but none of those letters has intrinsic meaning.

 

I like it. A reply that addresses the heart of the issue and actually makes sense. However, don't you think it's a bit of a coincidence that c^2 as an arbitrary number just happens to correspond exactly to twice the speed of light? Don't you think there must be a related and identifiable physical property that the two share?

[Erasmus00]

I'm glad someone posted this, as I have questions regarding this as well. Can someone better explain why c is squared? If c represents the speed of light and nothing can travel faster than light, how is squaring this speed factor relevant?

 

When you start working with the idea that physics should be the same in all reference frames, a number of things fall out. One of the things that happen is that time and space get put on equal footing. However, because we didn't know when we first started measuring time, we use the unit of the second, not the meter, for time. The numerical factor, c then is the conversion factor to go between seconds and meters.

 

If you continue with your new understanding of space and time, and you start over and rederive some of the foundations of Newtonian mechanics, like energy relationships, a number of strange results crop up. One of the results is the now famous equation for rest energy. i.e. a particle not moving at all, not in a gravitational potential at all, still has energy. The famous formula E=Mc^2. It turns out what we have been measuring as mass (in kg) is really another form of energy. c^2, then, is simply a factor to convert the units of mass from kg to J. It has nothing to do with "traveling at the speed of light in two dimensions." It is merely a conversion factor.

 

Proof of this equation is often attributed atomic bombs. Does this then mean as the materials of the bombs were accelerated via an explosion, the achieved or gave off the energy needed to cause such substantial damage?

 

In an atomic explosion, a very tiny percentage of the mass of the atoms is converted from mass energy to kinetic energy. This energy results in the explosion.

-Will

[EWright]

When you start working with the idea that physics should be the same in all reference frames, a number of things fall out. One of the things that happen is that time and space get put on equal footing. However, because we didn't know when we first started measuring time, we use the unit of the second, not the meter, for time. The numerical factor, c then is the conversion factor to go between seconds and meters.

 

If you continue with your new understanding of space and time, and you start over and rederive some of the foundations of Newtonian mechanics, like energy relationships, a number of strange results crop up. One of the results is the now famous equation for rest energy. i.e. a particle not moving at all, not in a gravitational potential at all, still has energy. The famous formula E=Mc^2. It turns out what we have been measuring as mass (in kg) is really another form of energy. c^2, then, is simply a factor to convert the units of mass from kg to J. It has nothing to do with "traveling at the speed of light in two dimensions." It is merely a conversion factor.

 

 

 

In an atomic explosion, a very tiny percentage of the mass of the atoms is converted from mass energy to kinetic energy. This energy results in the explosion.

-Will

 

Another insightful answer. Thanks for shedding light on that (pun intended). However, I'm still confused as to why c is used if it has nothing to do with the speed of light. I understand that it is a conversion factor to go between seconds and meters (time and distance), but does it not still correspond to the actual distance light travels in a given time? And if so, why precise relationship between time and distance and why exactly is it squared?