# Matter = E ?

energy
I would like to know whether matter is energy? Does Einstein's formula, E=MC^2, prove that matter is nothing more than energy... all the atoms, the table in front of you, the views from your window, and the air you breathe are just different configurations of the one fundamental property: energy?

Immediately after the big bang there was just energy, right? Everything else came later... from energy.

So, perhaps matter can’t be destroyed, but simply converts back to a less dense form of energy?

What do you think?

Homework Helper
Gold Member
E equals m (with c=1) for a particle at rest. This does not mean they are the same thing. For a particle with velocity, E increases while m is invariant.

Newbie says Hi
Well, the straight forward answer to your question is most definitely no!

I'll post the thoughts of one of our finer mentors for your physical considerations:

ZapperZ; said:
For those of you who think that mass can be defined as nothing more than "concentrated energy", consider the following:

Take an example of "pure" energy such as photons. Now clump them all very tightly to form as mass per the scenerio of the OP. Now explain to me the following:

1. photons have no charge, yet, electron, quarks, etc... all do. Where do these charges come from?

2. Photons have spin of 1. elementary fermions have spins of 1/2. How do you get the basic projection of the "units" of 1 to get spin of 1/2?

3. Photons do not interact via the weak interaction (they don't, at this point, participate in strong interactions either, but in some postulated theory, they might in higher order interactions). Yet, we know many particles that do. Where did that come from?

Zz.

Also, if we can say $$e=mc^2$$ means mass IS energy, then why not interpret the "=" (equal sign) in $$F=ma$$ to mean, force IS mass? I don't know if many people would accept that interpretation.

country boy
Also, if we can say $$e=mc^2$$ means mass IS energy, then why not interpret the "=" (equal sign) in $$F=ma$$ to mean, force IS mass? I don't know if many people would accept that interpretation.

But if we could say F=mXconstant, we might say "force is mass." By "is" we probably would mean "equivalent," as we do with energy and mass.

Since acceleration is not a constant in F=ma, we can't make the corresponding identification.

Different forms of energy occur elsewhere in Physics. In thermodynamics, work and heat are equivalent to energy in a manner similar to mass and energy. Sometimes we do say work "is" energy.

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pmb_phy
Also, if we can say $$e=mc^2$$ means mass IS energy, then why not interpret the "=" (equal sign) in $$F=ma$$ to mean, force IS mass? I don't know if many people would accept that interpretation.
I agreee. Just because E = mc2 this can't be taken to mean that mass is energy, only that an amount of energy absorbed or emitted by a body will increase that bodies mass according to that equation. Otherwise you could interpret the expression for a photon E = hf as meaning that energy and frequency are the same thing, and that'd be just plain silly.

Pete

energy
Thanks for the responses. I'm surprised that this question gets so many different answers from all the physicists I ask. Most here said no, yet many others believe matter is energy.

It's a little confusing that Einstein summarized his theory like this:

"It followed from the special theory of relativity that mass and energy are both but different manifestations of the same thing — a somewhat unfamiliar conception for the average mind. Furthermore, the equation E = mc², in which energy is put equal to mass, multiplied by the square of the velocity of light, showed that very small amounts of mass may be converted into a very large amount of energy and vice versa."

Could someone explain what he meant, if not that matter = energy?

Interestingly, he also said "“I believe in Spinoza's God, Who reveals Himself in the lawful harmony of the world, not in a God Who concerns Himself with the fate and the doings of mankind.”

Spinoza's philosophy states that everything that exists in Nature/Universe is one Reality (substance) and there is only one set of rules governing the whole of the reality which surrounds us and of which we are part. Spinoza argued that God and Nature were two names for the same reality, namely the single substance.

Sorry to bring God into it, but thought the second quote pertained to the discussion (regarding Einstein's meaning for his first statement).

Staff Emeritus
If your intention is to seek a physics answer, you already got it. If instead, you're seeking a philosophical discussion, this is the wrong forum. Please start another thread in the Philosophy forum, or I can move this thread there.

Zz.

energy
Sorry, ZapperZ. Didn't realize there was a philosophy area here at physicsforums. I would have asked there had I known.

The original question seems to generate both yes and no responses; from a purely scientific point of view, it's is worth further discussion/input. So, as long as philosophy is kept out of it, I can see no reason to move the thread.

Tomsk
Mass is not the same as matter. Mass, like energy, is a property of matter. Mass and energy are sort of equivalent by E=mc^2, but there is more to matter than mass/energy.

Staff Emeritus
But you seem to have missed the meaning of the responses. You'll see that in many cases, a "yes" has a "qualification" to it. For example, if you take something, smash it into bits, cook it, and turn it into something else, is that thing STILL the original object that you started with?

The problem here is that it appears you didn't understand the issues that someone quoted me earlier. You simply cannot just use ONE criteria (i.e. the energy equivalent of mass) and then go blind about the rest of its properties. It's like saying "Oh, it has the color of purple, so it must be Barney". You missed the fact that it is edible, it has a different taste, and that it is a beet! I listed several other properties of "mass" and "energy" that are not compatible with each other, but somehow those are ignored.

Just because something can be converted into something else, does not mean that those two are identical. People never confused "force" with "mass" in F=ma, or current is identical to potential difference in V=IR. Yet, they want to do that with E=mc^2, just because you can write that equal sign.

Zz.

Staff Emeritus
Gold Member
seems to generate both yes and no responses; from a purely scientific point of view, it's is worth further discussion/input. So, as long as philosophy is kept out of it, I can see no reason to move the thread.
Perhaps you are harboring some misconceptions here but I am yet to see a 'yes' response.

Edit: Zz beat me to it.

country boy
This question does seem to be more about the use of language than about the use of physics. If it is to be kept in the realm of physics, then the way to define energy, mass, or any quantity that enters the equations is in terms of how it is measured. This use of operational definitions is what ties theory to the physical world. If energy and mass were really the same, i.e., measured the same way, there would be no need for an equation to connect them.

Hmmm. This still feels like a philosophy discussion.

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energy
"For example, if you take something, smash it into bits, cook it, and turn it into something else, is that thing STILL the original object that you started with?" ZapperZ

That's probably not the best analogy Zz. It's not the original object, no... the original atoms have undergone changes, molecular configurations have altered... and some have even left the building... but the electrons, protons and neutrons are still electrons, protons and neutrons...

The 'yes' answers I spoke of have come from other forums. I haven't discounted what you're saying, on the contrary: I've found it very interesting. No need to expell "negative energy"...

energy
Perhaps you should move this to the philosophy forum if it bothers you so much, that was never my intention...

Staff Emeritus
"For example, if you take something, smash it into bits, cook it, and turn it into something else, is that thing STILL the original object that you started with?" ZapperZ.

That's probably not the best analogy. It's not the same object, no... the atoms have undergone changes... molecular configurations have altered... some have even left the building... but the electrons, protons and neutrons are still electrons, protons and neutrons...

But it is no longer the IDENTICAL THING. Something has been "coverted" into something else. Why people simply don't want to accept that, I am very puzzled.

The 'yes' answers I spoke of were from other forums. I haven't discounted what you're saying, on the contrary: I've found it very interesting.

Sorry, we don't do "other forums" on here. If we entertain every single thing said on "other forums", we'd be swamped with correcting a lot of mistakes and nothing else. PF is not unlike any other, and I should know since I've been on the 'net since 1989. You'll find that we have a significantly higher signal-to-noise ratio.

Zz.

anantchowdhary
'Energy' might be having a doubt on HOW mass is converted to energy

energy
And I thought mass was the property of a physical object that quantifies the amount of “matter and energy” it is equivalent to.

I know that m doesn’t equal E… I know this because m=E/c^2

My question was, does "matter" (not mass) equal E, is matter dense energy?

But, considering you know everything (with a healthy dose of arrogance thrown in), perhaps you could explain how the universe began as energy and matter magically sprang from it...

I suppose there is a special “quantum physics forum”, too?

Staff Emeritus
And I thought mass was the property of a physical object that quantifies the amount of “matter and energy” it is equivalent to.

I know that m doesn’t equal E… I know this because m=E/c^2

My question was, does "matter" (not mass) equal E, is matter dense energy?

But, considering you know everything (with a healthy dose of arrogance thrown in), perhaps you could explain how the universe began as energy and matter magically sprang from it...

Nope. Unlike you, I'm not smart enough to know the difference between "matter" and "mass". Maybe you'd care to enlighten me on what you define as "matter" and how you would quantify such a thing.

I suppose there is a special “quantum physics forum”, too?

I'm sure even you could have answered such a thing.

Zz.

energy
Nope.

Didn't think so. I made that deduction when you started getting rude... it's a natural progression...

Maybe you'd care to enlighten me on what you define as "matter"...

That's what I was asking the good people here. I thought it'd be obvious that I wouldn't have come here to ask the question if I knew the answer...

But it is no longer the IDENTICAL THING.

According to "our" terminology the words ‘matter’ and ‘energy’ are different; hence, we do not see them as the same thing… but that doesn’t mean they aren’t. My discussions with other physicists have made me aware of this possibility...

Quote: "Space has those properties, and you can consider energy to be a stress in some volume of it. This stress won't "stay still" unless it's traveling in a circle, whereupon it's matter, and it can hold some other stress still."

If it was universally known that matter isn't energy, then why do so many seemingly astute physicists think it is? There must be a possibility, at least... Therefore, not such a ridiculous question.

Staff Emeritus
Didn't think so. I made that deduction when you started getting rude... it's a natural progression...

Let's make one thing clear here, I wasn't being "rude". You were making a number of statements to counter what you were told in this thread, and I merely, in turned, questioned what you said. Somehow, challenging your perceived notion is now being 'rude'.

That's what I was asking the good people here. I thought it'd be obvious that I wouldn't have come here to ask the question if I knew the answer...

But you already are making a distinction between "matter" and "mass". As far as I can tell, you are making such a distinction for the first time. Is this something you got from "the other forum" also? Therefore, it is FAIR for me to then ask you on how you define such a thing. I never made such distinction, and as far as I know, in physics, such a thing is never made also.

According to "our" terminology the words ‘matter’ and ‘energy’ are different; hence, we do not see them as the same thing… but that doesn’t mean they aren’t. My discussions with other physicists have made me aware of this possibility...

This makes no sense. Who are these "other physicists"? Did you misinterpret what they were saying the same way you did here? Did they indicate to you that they often simplify their equations by letting c=1 and thus, E=m?

We cannot carry any rational discussion simply based on hearsay, and simply based on us trying to "translate" what you heard elsewhere. Please make more definite citation. If not, we will always try to argue against these phantom sources that may not even exist.

Quote: "Space has those properties, and you can consider energy to be a stress in some volume of it. This stress won't "stay still" unless it's traveling in a circle, whereupon it's matter, and it can hold some other stress still."

If it was universally known that matter isn't energy, then why do so many seemingly astute physicists think it is? There must be a possibility, at least... Therefore, not such a ridiculous question.

I would say that there is a huge amount of background knowledge that one needs to know before one start using the "stress energy tensor" in here, don't you think? Or else, you are simply quoting something you did not understand.

Zz.

country boy
I'm sorry to see how this discussion is going. It started out pretty interesting.

The distinction between matter and mass is a legtimate question, although I, too, am not able to answer it. It may be as simple as: mass is a property of matter.

Again, is this physics or philosophy?

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Staff Emeritus
The distinction between matter and mass is a legtimate question, although I, too, am not able to answer it. It may be as simple as: mass is a property of matter.

It might be. But if you notice, that isn't the original question. The distinction between "mass" and "matter" is only made recently, not in the OP. I have no knowledge to be able to separate out "mass" from "matter", and as far as I know, I haven't seen anyone else who can.

Again, is this physics or philosophy?

There is a reason right now why this isn't moved to the Philosophy forum, but it isn't something that can be discussed right now.

Zz.

energy
I simply reached the conclusion (right or wrong) that a distinction between "mass" and "matter" was necessary for matter= E, while keeping the two inextricably linked (i.e. assuming mass could represent the density of energy/matter).

Zz, as I said before, my intention was never to offend. I didn’t profess to be an expert; I imagined that was clear by my lack of understanding. My innate curiosity is the only impetus for asking these questions, not for the love of argument itself.

The word ‘God’ was used once in my posts in an attempt to qualify the meaning of Einstein’s previous statement; and, after having been met with opposition, I was more than happy to continue the discussion from a purely scientific standpoint, as mentioned.

Philosophy isn’t automatically necessary for my questions about energy, matter and mass, is it? I had the crazy idea that finding a complete understanding for these three things, and discovering a single fundamental property from which everything is made would be akin to the Holy Grail in physics. Again, my comparatively minuscule knowledge on this subject was the reason for such a misconception. My sincere apologies.

I do hope the discussion continues, though (on a more amicable tangent, of course!), and will try to remain a silent participant…

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tmc
Let's go back to basics. Zz tried to make this point, but you seem to have missed it.

Suppose c=1, as can easily be done by playing with your units.
Then, E=m.
This does not mean that matter and energy are the exact same thing. Rather, it means that a certain amount of mass can be converted into the same amount of energy.
There's nothing more to it.

energy
Thanks. I imagined that the reason for multiplying mass by c^2 may have been due to energy traveling at the speed of light. An erroneous assumption derived from the above idea that energy may travel in a circle (thus, appearing to “stand still”) forming matter (dense energy) in the process… and I stupidly thought the reason for squaring c was that, when matter was created, the energy was traveling in another direction at the speed of light also... as the universe expanded...

(and, what would a perfect theory be if not concise: gravity was the force created by this “alteration of state”… a force which travels at c... can you tell I write fiction?)

As I said, I best shut up and leave it to the experts

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anantchowdhary
mass cant travel at the speed of light!

energy
I understood that, but knew energy travels at c. My rationale was that as density and gravity increased velocity would decrease (not necessarily the speed of the original spinning energy... that of the subsequent mass created by gravity, I guessed).

So, yes, according to that principle (however misconceived!), “mass can’t travel at the speed of light”, but why it can’t was the point. A dense energy (matter) is limited by the opposing force (gravity) it creates by becoming dense (gaining mass). For every action there’s an equal and opposite reaction i.e. energy spinning at c gains density and creates the force of gravity. This gravity also travels at c. Therefore, for mass to travel at the speed of light, it would indeed take an infinite amount of energy… as it would no longer have mass… or be matter… but it’d 'be' infinite energy.

And didn't you know... pigs fly, too! ;)

*This has been edited, anantchowdhary's next comment was relating to my first paragraph, not the last comment about flying pigs :)

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anantchowdhary
well ,I also used to think so........But after i got a few lesons from ZapperZ i learnt a bit!

energy
Did I do this right?

c^2 divided by 360 degrees = 250,000,000

What a neat coincidence!

anantchowdhary
not exactly!

energy
Because the speed of light isn't considered to be exactly 300000 km/s ?

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anantchowdhary
yup thats right

MeJennifer
The speed of light is exactly 299792458 m / s, by definition!

energy
Thanks for the clarification. Much appreciated!

Thought I was on to something when I moved the decimal points on those incorrect figures equally '9' places:

90/.25 = 360

Right angle = 90 degrees

I figured that if the energy were traveling in a circle (360 degrees), creating an equal negative force (gravity), the circle must be proportional to the speed of both (c^2). It seemed logical to imagine that the characteristics of this small fundamental density would be the basis of all subsequent matter & forces (i.e. atoms, orbits, moons, planets, stars, etc. etc.)…

It also made sense that Ve = the square root of 2Gm/r... as well as being the reason for many other formulas.

Just goes to show how wrong you can be in this precise science

Thanks again for setting me straight (pun intended ;).

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energy
Unfortunately, I'm still having a hard time understanding the differentiation between matter and energy; obviously due to a lack on my behalf. If you wouldn't mind humoring me a little more, I have another question; the answer to which may be necessary for me to successfully separate matter from energy... or is that energy from matter?

Could someone explain why all atoms can absorb and/or reflect the visible spectrum (just one example of many interactions between matter and energy)?

If matter were not energy, isn’t it logical to assume that it wouldn’t have the capacity to interact with energy with such intrinsic synergy i.e. shouldn't two distinct substances have some inherent inability to affect each other… essentially differentiating the two as completely separate entities? Or did we just hit the veritable universal jackpot here?

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