E=mc^2

[I_Love_Cheese]

Yes, I know pound is both a mass and a force... one pound of force is the amount of energy needed to overcome gravities pull on one pound of mass...

Just because I question a basic concept doesn't mean I don't understand it. I understand it. It's wrong.

Your example in the first sentence where you equate force with energy shows that your second sentence where you state that you understand the subject is false.

Please show that you have some understanding by giving us the dimensions or dimensional units of E, F, m and c.

When you put these down you will see why your sentence is in error.

hint: inches,pounds,quarts etc are not part of the answer.

 

[caravelair]

Just because I question a basic concept doesn't mean I don't understand it. I understand it. It's wrong.

your arrogance is detestable. you clearly do NOT have a solid grasp on even basic physics (because if you did, you would not be having these problems getting your units straight), yet you claim einstein, (and basically all other physicists, since you will be hard pressed to find one who disagrees with his work in this area) to be wrong. do you REALLY think you know more about this than einstein did? or any other PHD physicist? honestly, you clearly know nothing about this. you are in no position to determine whether or not einstein was wrong.

 

[Kripost]

oooo this is why I like debating physics.. everyone assumes if they don't understand something it must be because the other person doesn't understand it. Yes I've taken highschool physics, and college physics, and read at least a few of hawking's work (good comedy). I've discussed this topic on various forums for at least... a good 200-300 hours... I'd say I've heard the theories just fine.

OK... let's start:

e=mc^2 says, regarless of any other factor, one unit of energy is equal to one unit of mass times a constant (light squared). This easily converts to any unit of mass times a constant is equal to a x units of energy. Using 300,000 kilometers per second (little less than that, but round numbers are nice), you can easily square that to 9x10^10. So one pound=9x10^10 kilometerpoundseconds worth of energy, or 9x10^16 meterpoundseconds

Besides using an ugly combination of metric and imperial units, the same mistake regarding units is still being made here.

"one pound=9x10^10 kilometerpoundseconds worth of energy"

Kilometre-pound-second or metre-pound-second is not a unit of energy.
In SI units, a unit of energy is 1 joule, where 1 J = 1 (kgm^2s^-2). Notice when expressed as basic SI units, it is mass x length ^2 x time ^ -2.
In imperial units, it is inch-pound, where pound refers to force. When broken down into basic units, you will still get mass x length ^2 x time ^-2, since force can be expressed as pound-inch per second-squared.
So any amount of energy can be expressed in terms of units of mass x length ^2 x time ^ -2.

On the other hand, metre-pound-second represents units of mass x length x time instead.

you said "[/SIZE][/COLOR][/FONT]Poundkilometerseconds is meaningless." And you're right. And E=MC^2 says exactly that because no one would question einstin on anything having to do with light.

Keep in mind Kripost said " You cannot drop the miles per second." So you're left with all units of measurement.

Example.... inchpounds is a certain amount of force applied at a certain arm. Likewise inchpoundseconds is what you're left with in E=MC^2.... oh I don't want to figure it out in inches... what's the speed of light in inches per second?

inch-pounds-seconds is not what you are left with in E=MC^2. There is a big difference between inch-pounds-seconds and inch-squared-pounds-per-seconds-squared.

Yes, I know pound is both a mass and a force... one pound of force is the amount of energy needed to overcome gravities pull on one pound of mass...

Just because I question a basic concept doesn't mean I don't understand it. I understand it. It's wrong.

The underlined section is fundamentally wrong: Force is not energy.

Forget about discussing einstein... It is better to start over with Newtonian classical mechanics.

 

[caravelair]

What if einstein weren't from america... would he assume E=MC^2 still? Even though in metric light is about 300,000 KM/second... therefore E=M x 90,000,000,000... now E=M times 90 billion?

So one pound has 90 billion poundkilometerseconds in it? I mean... if it's in billions you wouldn't measure it in kilometers... so 90 trillion pountmeterseconds?

Or what if it's a measure of light years per year instead of miles per second? 1... so E=m x 1 (since 1 squared is one).

no, i think you are misunderstanding here. listen: there are different units that can be used to measure energy. the equations will work out provided you keep your units straight. one joule of energy is defined as one Kg(m^2)/(s^2), or one kilogram times 1 metre squared divided by one second squared. therefore if you use kilograms as your unit of mass and metres/second as your unit of velocity for the speed of light, you will get your unit of energy in joules on the left side of the equation. if you use inches/second instead, you will get the same answer but it will be represented in different units. it will not be represented in joules, but rather in kilogram(inches^2)/s^2, which can easily be converted to joules by multiplying by metres/inch twice.

einstein did not assume E=MC^2, he derived it. see the link someone else provided for details.

 

[Frumious Bandersnatch]

no, i think you are misunderstanding here. listen: there are different units that can be used to measure energy. the equations will work out provided you keep your units straight. one joule of energy is defined as one Kg(m^2)/(s^2), or one kilogram times 1 metre squared divided by one second squared. therefore if you use kilograms as your unit of mass and metres/second as your unit of velocity for the speed of light, you will get your unit of energy in joules on the left side of the equation. if you use inches/second instead, you will get the same answer but it will be represented in different units. it will not be represented in joules, but rather in kilogram(inches^2)/s^2, which can easily be converted to joules by multiplying by metres/inch twice.

einstein did not assume E=MC^2, he derived it. see the link someone else provided for details.

Actually the equation was derived by Einstein and others but it has proven useful. IIRC differences in predicted and measured energy in beta decay led to the discovery of the neutrino for example.

Part of the problem here may be that the equation is not quite that simple in real situations. The famous equation:

E=mC^2

is used to calculate the energy of a particle at rest.

C is defined as exactly 299,792,458 m/sec

So in joules a kg of particles with no kinetic energy (no momentum) is about 9x10^16 Joules or about 25 billion kilowatt hours in other units.

The equation that you need to use to compare hot lava to ice for example is

E^2 = p^2C^2 + m^2C^4

To do this in theory you would sum this up for each individual atom in either the lava or the ice. The atoms have momentum, p, even in ice as they are vibrating around equilibrium positions in the crystal as long as T is not 0 K.

In practice you could try to calculate the total thermal energy by integrating the heat capacity with temperature from your starting temp to 0 Kelvin taking the latent heat of phase changes into account. The heat capacity of basalt is about 1000 J/kgK and the heat of fusion is about 400 kJ/kg if anyone wants to do the calculation I am sure you can find heat capacities for rocks and ice. You will see that the numbers will be large but tiny compared to the matter energy conversion.

Hope this doesn't add too much to the confusion.

 

[Osiris]

Einstein says E=MC^2.... right? Energy=Mass x speed of light squared.

Mass... say one pound is equal to a certain amount of energy... but mass is less than energy because it takes a lot of energy to make mass. That's what einstein was getting at, and I agree...

I wouldn't say mass is less than energy, I'd say it is more... because a little bit of mass = a lot of energy.

1000 units of mass is > than 1000 units of energy.

 

[The Gregorian]

The formula's simple... the problem is people keep saying the unit's wrong, so I substitute it with a new unit... the formula's still simple... the problem is why?

Is E=mc^2 just a formula for finding jouls?

I can understand how it sounds like I'm questioning the wrong thing because I don't accept the fundamental the formula is based upon. Any highschool book will tell you the theory completely and utterly relys on SR... light has to be a constant, and any time we see light moving at a different speed (any time we observe the red/blue shift of a star moving relative to us) that's not really light moving at a different speed relative to us, that's time slowing down, thus changing the frequency of light.

That is what I reject. Reject the flawed fundamental of special relativity and you inherently reject all theories relying on it.

Yes, matter can be converted to energy and vice versa... but why bring the speed of light into it? The speed of light is only a constant in a given medium... as is any wave. Common known fact that light travels faster in the vacuum of space than in our dense, heated atmosphere... but our observations are obviously flawed since time is dilating to suit einstein's needs, when there is no evidence that time dilates at all, nore is there evidence that time is something that can be dilated.

I was trying to get at the flaw of putting the speed of light in the Energy formula because the speed of light isn't a constant... only a constant in a given medium relative to it's source.

To measure a joul as mass times (c^2) is not magic... it doesn't rely on light being a constant... it's simply mass times a number... any number can replace it and the only thing different will be the 'size' of the unit of measurement.

 

[The Gregorian]

The equation that you need to use to compare hot lava to ice for example is
E^2 = p^2C^2 + m^2C^4
Hope this doesn't add too much to the confusion.

No, I appriciate people actually going along with the discussion instead of "MY BOOK SAYS THIS SO IT RIGHT!!!!! You R dum!"

Remember newton disagreed with the books telling us gravity didn't exist... then einstein disagreed with newton and 'proved' gravity didn't exist" (in his claim that there is no force of gravity only mass bending spatcieme around itself. I spell it that way because einstein mixes up space and time too readily... space is not time. they are not interchangable, they are not equal.)

 

[Frumious Bandersnatch]

The formula's simple... the problem is people keep saying the unit's wrong, so I substitute it with a new unit... the formula's still simple... the problem is why?

Is E=mc^2 just a formula for finding jouls?

No it is the formula relating rest mass to energy. You can find a derivation here.

I can understand how it sounds like I'm questioning the wrong thing because I don't accept the fundamental the formula is based upon. Any highschool book will tell you the theory completely and utterly relys on SR... light has to be a constant, and any time we see light moving at a different speed (any time we observe the red/blue shift of a star moving relative to us) that's not really light moving at a different speed relative to us, that's time slowing down, thus changing the frequency of light.

We never see light moving at a different speed in a vacuum. It is a constant the is determined by the by the permittivity and permeability of free space as shown by Maxwell's equations.

That is what I reject. Reject the flawed fundamental of special relativity and you inherently reject all theories relying on it.

Yes, matter can be converted to energy and vice versa... but why bring the speed of light into it? The speed of light is only a constant in a given medium... as is any wave. Common known fact that light travels faster in the vacuum of space than in our dense, heated atmosphere... but our observations are obviously flawed since time is dilating to suit einstein's needs, when there is no evidence that time dilates at all, nore is there evidence that time is something that can be dilated.

Where do you get this idea. Time dilation has been demontrated using atomic clocks on airplanes.

I was trying to get at the flaw of putting the speed of light in the Energy formula because the speed of light isn't a constant... only a constant in a given medium relative to it's source.

The speed of light is constant in a vacuum and constant to any observer.

To measure a joul as mass times (c^2) is not magic... it doesn't rely on light being a constant... it's simply mass times a number... any number can replace it and the only thing different will be the 'size' of the unit of measurement.

The calculation relies on the speed of light in a vacuum which is a constant. The meter is defined by the speed of light. If you use other units you get other numbers but the "values" are the same.

 

[Merlin]

Mexwell developed equasions for the behaviour of light or electromagnetism.
Einstein explored whether Maxwell's work could be expanded to include matter (mass).

My question is why does einstein butt 'light' into everything? Why not just say E=M times a certain number?

He did. Einstein showed a relationship of rest mass and energy. Energy=Mass times a constant (C) squared.
C also dictates the velocity of light in a vacuum.
Einstein didn't 'butt' light into things. Other people do.
It's just easier to say 'light squared' to help people understand the equasion.

 

[Frumious Bandersnatch]

Mexwell developed equasions for the behaviour of light or electromagnetism.
Einstein explored whether Maxwell's work could be expanded to include matter (mass).


He did. Einstein showed a relationship of rest mass and energy. Energy=Mass times a constant (C) squared.
C also dictates the velocity of light in a vacuum.
Einstein didn't 'butt' light into things. Other people do.
It's just easier to say 'light squared' to help people understand the equasion.

Actually Eiinstein derived the equation for inertia. You can find an English translation of his paper HERE.

Added in edit: He wrote
If a body gives off the energy L in the form of radiation, its mass diminishes by L/c². The fact that the energy withdrawn from the body becomes energy of radiation evidently makes no difference, so that we are led to the more general conclusion that
The mass of a body is a measure of its energy-content; if the energy changes by L, the mass changes in the same sense by L/9 × 1020, the energy being measured in ergs, and the mass in grammes.

 

[Lucretius]

Remember newton disagreed with the books telling us gravity didn't exist... then einstein disagreed with newton and 'proved' gravity didn't exist" (in his claim that there is no force of gravity only mass bending spatcieme around itself. I spell it that way because einstein mixes up space and time too readily... space is not time. they are not interchangable, they are not equal.)

The word isn't out on gravity yet.

Newton didn't argue with people about gravity because he developed the very concept.

I would say it seems early to throw in the towel on a theory of gravity that relies on gauge bosons (carrier particles, like photons, W and Z bosons, and gluons). Remember that both Einstein's theory and Quantum theory falls apart (when seen separately) in regions like black hole singularities and the Planck Epoch. We need to unify them, and because 3 out of 4 of the Fundamental Forces are explained relying on gauge bosons — I'd say it isn't crazy to assume gravity is too — it's just so weak that it's nigh impossible to detect.

Space and time might not be the same, but they are related. If one warps space it also affects time. This is demonstrably true.

 

[OdwinOddball]

The formula's simple... the problem is people keep saying the unit's wrong, so I substitute it with a new unit... the formula's still simple... the problem is why?

Is E=mc^2 just a formula for finding jouls?

I can understand how it sounds like I'm questioning the wrong thing because I don't accept the fundamental the formula is based upon. Any highschool book will tell you the theory completely and utterly relys on SR... light has to be a constant, and any time we see light moving at a different speed (any time we observe the red/blue shift of a star moving relative to us) that's not really light moving at a different speed relative to us, that's time slowing down, thus changing the frequency of light.

That is what I reject. Reject the flawed fundamental of special relativity and you inherently reject all theories relying on it.

Yes, matter can be converted to energy and vice versa... but why bring the speed of light into it? The speed of light is only a constant in a given medium... as is any wave. Common known fact that light travels faster in the vacuum of space than in our dense, heated atmosphere... but our observations are obviously flawed since time is dilating to suit einstein's needs, when there is no evidence that time dilates at all, nore is there evidence that time is something that can be dilated.

I was trying to get at the flaw of putting the speed of light in the Energy formula because the speed of light isn't a constant... only a constant in a given medium relative to it's source.

To measure a joul as mass times (c^2) is not magic... it doesn't rely on light being a constant... it's simply mass times a number... any number can replace it and the only thing different will be the 'size' of the unit of measurement.

Do you know what a GPS system is?

Do you know how they work?

Do you understand that without Relativity, GPS systems would be impossible?

In order for a sattelite orbiting the earth to pinpoint your position, it must use the principles of relativity. First the signals travveling to and from the sattelite have to be corrected due to the shift in frequency of electromagnetic signals when travelling thru a changing gravitational field.(ie gravity is stronger at the earths surface than at the sattelites orbit) Also, you have to allow for time dilation, as sense the sattelite is orbiting the earth at a great velocity and in a less strong gravitational field, its speed slows down time. These are observed effects. They are not something just made up. Without using relativity to compensate for these effects GPS systems would not be possible.


Without using relativity, we could not launch probes to Mars. We could not build nuclear bombs. Neil Armstrong and crew would not have been able to visit the Moon.

You are making the same mistake many people on this forum make. You do not understand a subject, so you claim it is false. This is not a good argument, all it serves to do is demonstrate your ignorance, and does more harm to your "side" than any atheists could ever hope to acomplish.

 

[I_Love_Cheese]

The formula's simple... the problem is people keep saying the unit's wrong, so I substitute it with a new unit... the formula's still simple... the problem is why?

Is E=mc^2 just a formula for finding jouls?

I think I see what you are actually questioning, and I will see if I can explain a little. I will stipulate that you have taken the requisite courses since you do seem to know the terminology.

Your real question is why is the number that relates Energy to mass equal to the speed of light in a vacuum? The answer in some ways is that it doesn't have to be but as far as we can measure it, that is what it is.

To go back to the dimensional units discussion what I was trying to get at is the following. I will assume that you accept E=1/2mv^2 which is the formula for kinetic energy at speeds small relative to the spped of light as Newton found. This is basic high school physics.

The point is that mv^2 has dimensional units of mass * length^2 / time^2 and these are the dimensional units of Energy or E. In the SI system we use the Joule as the unit of energy. The Joule is defined as a kg*meter^2/second^2, which in more basic units is mass(kg) times length^2 (meters^2) all divided by seconds^2 (time^2).

What Einstein discovered/derived/predicted is that there is also an energy equivalent to the rest mass of an object itself which follows the same pattern. The energy bound up in the atomic forces in an object is related to the mass of the object by a similar equation.

Lets call the equation E/m = k. This equation by basic algebra says that the ratio of energy to mass is a constant.

This equation has been experimentally verified many times in nuclear reactors and other radioactive decay experiments. But what is k the constant of proportionality.

Energy has units of mass*length^2/time^2 which has been known since Newton. When we divide out the mass we are left with k has units of length^2/time^2 which you should recognize as the units of velocity (distance/time) times itself. So what is the value of this k which by dimensional analysis must be the square of a velocity. Well even without Einsteins theory, all experiments thus far have determined that it is ~186,000miles/second or the speed of light in a vacuum. In other words, it is not an arbitray number or rather it could be but it turns out to be the speed of light.

In fact that the number is the speed of light is often used as a part of the fine tuning argument for the existence of god.

I can understand how it sounds like I'm questioning the wrong thing because I don't accept the fundamental the formula is based upon. Any highschool book will tell you the theory completely and utterly relys on SR... light has to be a constant, and any time we see light moving at a different speed (any time we observe the red/blue shift of a star moving relative to us) that's not really light moving at a different speed relative to us, that's time slowing down, thus changing the frequency of light.

As I showed above, you do not have to accept SR but the formula works whether you accept it or not. If you do not accept SR, come up with a better explanation for why the formula works.

Yes, matter can be converted to energy and vice versa... but why bring the speed of light into it? The speed of light is only a constant in a given medium... as is any wave. Common known fact that light travels faster in the vacuum of space than in our dense, heated atmosphere... but our observations are obviously flawed since time is dilating to suit einstein's needs, when there is no evidence that time dilates at all, nore is there evidence that time is something that can be dilated.

The reason for the change in the apparent value of the speed of light in other than vacuum environments is another story but it basically has to do with the fact that photons are absorbed and then reemitted by the matter they are travelling through and this process of absorbtion and reemmision accounts for the difference in time.

I was trying to get at the flaw of putting the speed of light in the Energy formula because the speed of light isn't a constant... only a constant in a given medium relative to it's source.

see above and the speed of light through matter is another discussion.

To measure a joul as mass times (c^2) is not magic... it doesn't rely on light being a constant... it's simply mass times a number... any number can replace it and the only thing different will be the 'size' of the unit of measurement.

Exactly the point it is not magic and any number could replace it but the number that does is the speed of light in a vacuum. This coincedence is often taken as evidence of a god, thus our confusion over why you seem to want to dismiss it.

 

[Merlin]

Actually Eiinstein derived the equation for inertia. You can find an English translation of his paper HERE.

And the paper starts off:
I based that investigation on the Maxwell-Hertz equations for empty space, together with the Maxwellian expression for the electromagnetic energy of space

 

[Frumious Bandersnatch]

A couple of links

E=mc2 passes tough test.

Einstein explains E=MC2

 

[Mocca]

Okay, dude, you keep your frakking units. Seriously, you carry them with you where-ever you go. They're precious. I'll explain why.

Say, lets start with two amounts:
3 meters, and 1 second. When you divide them without the units, you get 3. When you divide them with the units, you get 3 meters/second. So, if you keep the units in the equations, you get meaningful results!

You can do operations on units! For example, meters / second is a division of units!

In fact, some combinations of these units are meaningful and used very often, and are given shortened names. For example, kg * m / sec^2 is known as the newton, a measure of force. Instead of writing kg * m / sec^2 we write the newton, because it's shorter.

Now I'll show that the units in e = mc^2 work.

m is mass, in kg. c^2 is the speed of light squared, and therefore is meters^2/seconds^2. If you multiply them, you get kg * m^2 / sec^2. This unit is known as the joule, which is a measure of energy, the e in the equation. It works.

The units are incredibly meaningful and important. Say, if you didn't use 5 meters per second and just used 5, you now have a rather meaningless expression. This is because meters per second are 2.236936 times miles per hour. How are we supposed to know what unit the number is in? It could be in furlongs per fortnight, for all we care.

Conclusion: units matter.

Edit: Oh yeah, when you're talking about dropping the meters per second or miles per second, you're incredibly incorrect. As you may know, it's the speed of light squared. And as we keep the units with the numbers at all times, and we can perform operations on units, instead of meters per second it's meters ^ 2 / seconds ^ 2.

I'm seriously doubting your claim to have taken a course in college physics, whatever that is. If you have, from what you've stated in your previous posts, you haven't learned it well.

 

[caravelair]

I can understand how it sounds like I'm questioning the wrong thing because I don't accept the fundamental the formula is based upon. Any highschool book will tell you the theory completely and utterly relys on SR... light has to be a constant, and any time we see light moving at a different speed (any time we observe the red/blue shift of a star moving relative to us) that's not really light moving at a different speed relative to us, that's time slowing down, thus changing the frequency of light.

actually, this has nothing to do with time slowing down. this is a shift in the frequency of light, it has nothing to do with the velocity of light.

That is what I reject. Reject the flawed fundamental of special relativity and you inherently reject all theories relying on it.

what is flawed about special relativity? surely you have some falsifying evidence. please present it.

Yes, matter can be converted to energy and vice versa... but why bring the speed of light into it?

why don't you take a look at how the formula was derived, and then you might have an answer to that.

The speed of light is only a constant in a given medium... as is any wave. Common known fact that light travels faster in the vacuum of space than in our dense, heated atmosphere...

and c is the speed of light in a vacuum, which is a constant. so what is your point?

but our observations are obviously flawed since time is dilating to suit einstein's needs,

what? that makes no sense.

when there is no evidence that time dilates at all, nore is there evidence that time is something that can be dilated.[/quote

actually, that is not true. there is direct evidence that time does dilate. for example, they have placed atomic clocks that were synchronized, one on a plane, and one on the ground, and they were found to have a difference in the time that passed for each clock.

I was trying to get at the flaw of putting the speed of light in the Energy formula because the speed of light isn't a constant... only a constant in a given medium relative to it's source.

and c represents the speed of light in a vacuum, which is a constant.

why do you keep on insisting that this is a flaw in the formula, when clearly it is only a flaw in your understanding of it.

To measure a joul as mass times (c^2) is not magic... it doesn't rely on light being a constant... it's simply mass times a number... any number can replace it and the only thing different will be the 'size' of the unit of measurement.

no, if you replace c with another velocity, you will not get accurate results.

 

[caravelair]

Remember newton disagreed with the books telling us gravity didn't exist... then einstein disagreed with newton and 'proved' gravity didn't exist" (in his claim that there is no force of gravity only mass bending spatcieme around itself. I spell it that way because einstein mixes up space and time too readily... space is not time. they are not interchangable, they are not equal.)

well then you should explain why general relativity produces accurate results, and newtonian gravity does not, at least in certain situations. until you do so, general relativity will remain the best explanation we have for gravity.

 

[Mocca]

Eh, flawed response to a vague claim.