matter /= energy?

[Baby Astronaut]

Am I correct to say that matter only contains -- instead of is -- energy?

 

If so....the reason for this poll is get an idea of how many people actually once thought the reverse, incorrectly -- with energy as some real (but insubstantial) thing in air or space, visible only in the form of lightning or detectable as photons?

[ajb]

Energy is a property of "stuff" including particles and waves.

 

The confusion comes down to [math]E = mc^{2}[/math] and the terminology that "photons are pure energy".

[Baby Astronaut]

But did you have that confusion ever in your life? That's what the poll's for

[ajb]

I must confess that it did course confusion in the past.

[walkntune]

Nikola Tesla once remarked, "This new power for the driving of the world's machinery will be derived from the energy which operates the universe, the cosmic energy, whose central source for the earth is the sun and which is everywhere present in unlimited quantities. "

 

Tesla seems to have thought that energy was the culprit that is everywhere and operates everything.

It doesn't seem correct to me that it's just a property of matter. I know science wants to be able to put a math and a prediction on all observations so energy has to be treated as a property that is measured from one mass to another.In reality though I think matter is just a property of energy and energy exists everywhere just like nikola is quoting above.

If this is not true than why does everything decompose back into energy?

[insane_alien]

nikola, while he had some brilliant ideas and was quite smart, was also pretty messed up in the head and got a LOT of stuff wrong. you cannot take anything he said as being completely true just because he said it.

 

this is actually called arguement from authority fallacy. sure, someone famous said it but that doesn't mean they are right. Einstein spent a lot of his later years trying to get rid of quantum mechanics because he didn't like it. but it's here to stay.

 

also, science has moved on in leaps and bounds since tesla, his ideas are at the very least outdated.

[ajb]

If this is not true than why does everything decompose back into energy?

 

Could you elaborate on this statement?

[walkntune]

Could you elaborate on this statement?

 

When something decays, the mass of particles is less than that of the original before the decomposition.Therefore what became of the original mass? It must have either turned into heat or went in the ground or maybe was eating and used for energy by another energy source(animal).

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Merged post follows:

Consecutive posts merged

nikola, while he had some brilliant ideas and was quite smart, was also pretty messed up in the head and got a LOT of stuff wrong. you cannot take anything he said as being completely true just because he said it.

 

this is actually called arguement from authority fallacy. sure, someone famous said it but that doesn't mean they are right. Einstein spent a lot of his later years trying to get rid of quantum mechanics because he didn't like it. but it's here to stay.

 

also, science has moved on in leaps and bounds since tesla, his ideas are at the very least outdated.

 

Not being a scientist I still search for truth and take a very open stance to the different scientific opinions that are much debated. I am grateful that being in this age of information I can get access to lots of scientific opinions and try and way them out to what seems more plausible as being correct.I didn't have to spend years learning one sided opinions and have to way them out in debates and I actually really don't care to as it's far more important to me to be able to be a help and encourager to others than prove my own knowledge correct(which actually is not mine but just searching for truth in others who I am grateful spent their time in study).

This being said I still have a pretty good sense of logic and reasoning and I don't just take someone at their word for truth.I way it out with what I observe in the real world and try to come to understand there points of view.

I do favor string theory over QM as I feel everything is energy in a certain form and I think string theory would be in favor of that.

I guess what's amazing to me is that I had no idea about string theory and I just came into the forum to understand my concept of energy that I sense so strong in our world and universe so although it may not fit into your world of numbers and theories, it fits into the world I observe and has caught my interest to at least learn of it.

I actually really don't care to as it's far more important to me to be able to be a help and encourager to others than prove my own knowledge correct

Don't want this taken wrong. In other words, I take the knowledge I gain in the forums and I use it to help drug addicts in rehabs, abused children etc....

Edited November 26, 2009 by walkntune
Consecutive posts merged.

[ydoaPs]

Tesla seems to have thought that energy was the culprit that is everywhere and operates everything.

 

Many a crackpot hold Tesla up as a god. Truth be told, Tesla got more wrong than right.

 

When something decays, the mass of particles is less than that of the original before the decomposition.Therefore what became of the original mass? It must have either turned into heat or went in the ground or maybe was eating and used for energy by another energy source(animal).

mass≠matter

[ajb]

When something decays, the mass of particles is less than that of the original before the decomposition.Therefore what became of the original mass? It must have either turned into heat or went in the ground or maybe was eating and used for energy by another energy source(animal).

 

In decays (and collisions) the four-momentum is the thing to study.

 

If I recall rightly, in the rest frame you get conservation of mass.

Edited November 26, 2009 by ajb
poor wording originally

[walkntune]

mass≠matter

 

I have no idea what matter is so I don't know? Is matter made up of particles or is it strings of energy?

[JillSwift]

I have no idea what matter is so I don't know? Is matter made up of particles or is it strings of energy?

Yes.

 

Mind, the words are just handy labels. They don't define anything absolutely, and only work well within a given context.

 

Its nonintuitive, because our brains are the result of evolution within the context of matter-as-objects.

[J.C.MacSwell]

In decays (and collisions) the four-momentum is the thing to study.

 

If I recall rightly, in the rest frame you get conservation of mass.

 

I'm not sure what definition of mass would allow that. I think it would require photons to be considered to have mass.

 

Perhaps you are thinking of momentum?

[ajb]

I'm not sure what definition of mass would allow that. I think it would require photons to be considered to have mass.

 

Perhaps you are thinking of momentum?

 

Yes. Slip of the tongue (and fingers!)

 

If one species decays into two others it is not hard to show that in the center of momentum for the two daughter species we have

 

[math]Mc^{2}= (m_{1}+ m_{2})c^{2}[/math]

 

with [math]M[/math] being the parent mass and [math]m_{i}[/math] the mass of the daughter species.

 

So in this sense we do have conservation of mass.

 

In "relativistic billiards" the things to keep track of are the linear momentum and the energy.

[timo]

If one species decays into two others it is not hard to show that in the center of momentum for the two daughter species we have

 

[math]Mc^{2}= (m_{1}+ m_{2})c^{2}[/math]

 

with [math]M[/math] being the parent mass and [math]m_{i}[/math] the mass of the daughter species.

Whatever you've been thinking of there, I think it is wrong.

 

poss a) You you mean a decay where kinetic energy is negligible then the conservation of mass is only as true as the approximation you did (your equation would then be conservation of energy). Strictly speaking, I don't think it could ever be exact because you need some non-zero final-state phase space volume for a reaction to happen (excitation daughter particles might provide some phase space, though).

 

poss b) If you were thinking of the pseudo-magnitude of 4-momentum to be conserved then the problem is that in general [math] \| \vec a + \vec b \| \neq \| \vec a \| + \| \vec b \|[/math]; in the letters of your example: [math] M = \| P \| = \| p_1 + p_2 \| \neq \| p_1 \| + \| p_2 \| = m_1 + m_2[/math]. By that I mean: The momentum is conserved, of course. So is its pseudo-magnitude which is sometimes even called the invariant mass of a system of particles. It is however not true that the sum of the individual decay products' mass was equal to this invariant mass; the simplemost counter example being Positronium (m roughly 1 MeV) decaying to photons (no mass individually).

 

poss c) You might have meant relativistic mass above (I doubt it) but there'd be no reason not to call it "energy" in the first place.

[ajb]

I manage to get

 

[math]Mc^{2}= \frac{(m_{1}+ m_{2})(m_{1}-m_{2}) c^{4}}{(E_{1}-E_{2})}[/math]

 

in the rest frame of the initial particle.

 

Then I consider the frame in which [math]E_{1}- E_{2} = (m_{1}-m_{2})c^{2}[/math]. Maybe this last step is unphysical?

[timo]

I do not understand what you do there. Take positronium to 2 gamma as an example. In the cms frame the momentum of the positronium is [math]P^\mu = (M, 0, 0, 0)[/math]. Let the gammas fly out parallel to the z-direction. They then have the momentum [math]p_1^\mu = (M/2, 0, 0, M/2)[/math] and [math]p_2^\mu = (M/2, 0, 0, -M/2)[/math], respectively. This does of course conserve momentum as [math] P = p_1 + p_2 [/math]. The mass of a single particle is the pseudo-magnitude of its momentum, i.e. [math]M = \| P \|[/math] and [math] m_1 = m_2 = \sqrt{p_i^{\mu} p_{i,\mu}} = 0[/math]. Hence [math] M \neq m_1 + m_2[/math]. Of course it holds true that [math] M = \| P \| = \| p_1 + p_2 \|[/math] - that is just a weaker version of conservation of momentum (if a vector remains constant that naturally its magnitude also does). Perhaps the best question to understand what you do would be: What is M, m1 and m2?

[ajb]

Thinking of a decay like

 

[math]m_{1} \leftarrow M \rightarrow m_{2}[/math]

 

considered in the rest frame of [math]M[/math]. I will use [math]m_{I}[/math] to be the rest mass of the daughter particles and [math]M[/math] to be the mass of the parent.

 

We also have to consider the energy and momentum.So, [math]p_{I}[/math] is the linear (3-momentum) and [math]E_{I}[/math] the energy.

 

So, in the rest frame of [math]M[/math] we have

 

(1) [math]p_{1}= p_{2}[/math]

 

by conservation of momentum.

 

(2) [math]E_{1} + E_{2} = Mc^{2}[/math]

 

by conservation of energy.

 

Then (1) implies

 

[math]c^{2}p_{1}= c^{2}p_{2}[/math].

 

Using the mass-shell condition we get

 

[math] E_{1}^{2}- m_{1}^{2}c^{4} = E_{2}^{2}- m_{2}^{2}c^{4}[/math].

 

Rearranging

 

[math]E_{1}^{2}- E_{2}^{2} = (m_{1}^{2}-m_{2}^{2}) c^{4}[/math]

 

or

 

[math](E_{1}+ E_{2})(E_{1}-E_{2}) = (m_{1} + m_{2})(m_{1} - m_{2})c^{4}[/math].

 

Then using (2)

 

[math]Mc^{2} = \frac{(m_{1}+m_{2})(m_{1}-m_{2})c^{4}}{(E_{1}-E_{2})}[/math].

 

Which I am sure is ok. The last step of picking a frame in which we have no momentum is possibly wrong. Well, I am almost sure it is wrong.

Edited November 27, 2009 by ajb

[timo]

[...] then

[math]Mc^{2} = \frac{(m_{1}+m_{2})(m_{1}-m_{2})c^{4}}{(E_{1}-E_{2})}[/math].

 

Which I am sure is ok. The last step of picking a frame in which we have no momentum is possibly wrong. Well, I am almost sure it is wrong.

Apart from a few typos (p1=-p2, not p2) and potential problems with your denominator I have no real objections, yes .

 

There's two objections I have to the last step but I can't put my finger on it, atm. Anyways, those two objections are:

1) You derived an equation in the cms (=center-of-mass = system where the total 3-momentum is zero) frame. In that equation you have something that transforms like a Lorentz scalar on the left side and something that probably transfers like inverse of the 0-element of a vector. Your equation would probably not survive a boost into a different system.

2) I don't think there is such a system. In the cms frame you have the two daughter particles flying apart back-to-back. To which direction would you want to boost that both daughter particles have zero momentum?

Edited November 27, 2009 by timo
tyop

[ajb]

There's two objections I have to the last step but I can't put my finger on it, atm.

 

It too has me a little stumped.

 

I am sure my expression is right , but attempting to interpret it or boost to other frames my not be clear. I did as you say derive it in a very specific frame.

[Mr Skeptic]

Energy is always in some form or another. Matter is one of the many forms that energy may have, and there are several types of matter.

 

why does everything ecompose back into energy?

 

It doesn't. Sometimes energy "decomposes" into matter. For example, creation of a particle/anti-particle pair from a photon, or from kinetic energy of particles.