What exactly is energy?

[studiot]

Ken, your first post shows a curious mixture of fact and fallacy.

 

Yes energy has to do with motion.

No you do not need energy to change direction od motion.

Yes energy and force are different independent quantities, you can have either without the other.

Yes they are often connected through motion.

 

But that is not the explanation you seek.

 

My best advice is to read the delightful monograph by Professor Peter Atkins of Oxford University

 

'Four Laws that drive the Universe'

 

Three of his four laws discuss physical phenomena that introduce and define a physical property.

The second of these is energy and he give clear explanations to all my above statements and much more besides.

 

The book does not require significant knowledge of mathematics.

[Nicholas Kang]

The equation says that mass is a form of energy. It does not say anything about either being a conserved quantity, and mass is not a conserved quantity.

 

Mass is a form of energy means we have mass energy? But not mass-energy? (Note the dash sign)

[swansont]

 

Mass is a form of energy means we have mass energy? But not mass-energy? (Note the dash sign)

 

I'm not sure what the dash sign is supposed to signify.

[Dekan]

Could it signify this - that there isn't one, single, primary, "thing" which deserves the name "mass-energy".

 

Rather, "mass" is just a different form, or manifestation, of energy.

 

Just as "heat" and "light" are different manifestations of photons. I suppose we could invent a new name: "heat-light". But would it be scientifically useful?

[swansont]

Could it signify this - that there isn't one, single, primary, "thing" which deserves the name "mass-energy".

 

Rather, "mass" is just a different form, or manifestation, of energy.

 

Just as "heat" and "light" are different manifestations of photons. I suppose we could invent a new name: "heat-light". But would it be scientifically useful?

 

In relativistic kinematics, there is mass energy and there is kinetic energy. The sum of which give you the total energy.

 

 

Heat is not always photons, and sometimes light is heat. Sometimes it isn't. The situation is much more nuanced.

[hoola]

isn't the "quantum fluctuation of space" the virtual particle phenomena?

[Nicholas Kang]

In relativistic kinematics, there is mass energy and there is kinetic energy. The sum of which give you the total energy.

 

You have answered my question. Thank you, Dr.swantson

[Mordred]

isn't the "quantum fluctuation of space" the virtual particle phenomena?

 

Yes [latex]e=\frac{1}{2}hv[/latex]

Edited July 23, 2014 by Mordred

[hoola]

I think a weak definition of the term could be "the ability for certain segments of universe to communicate within and between themselves to produce change" as it lacks any activator of that ability...I see the conservation of energy as a little off. Some infintesimal energy is added everywhere, or else the universe wouldn't be expanding...so, within local input/output interactions the law holds, but additional energy is always added due to local dark energy within the region...but dark energy may not interact in any particular way with local energy exchanges so never gets measured... perhaps at event horizons there is an interaction...

[Sensei]

But questions such as "what is an electron" and your questions cannot be answered in this way. These are (as far as we know) fundamental things. We can we can quantify them and describe them in terms of their interactions with other things. But they are what they are.

 

It can be answered by analyze of what happens to electron while annihilation with positron, and production of gamma photons.

They are later absorbed and emitted with less, and less energy, with more quantity...

 

Single pair of electron-positron has enough energy to heat 1.3 billions of H₂O molecules for 1^o C.

 

[Strange]

 

It can be answered by analyze of what happens to electron while annihilation with positron, and production of gamma photons.

They are later absorbed and emitted with less, and less energy, with more quantity...

 

Single pair of electron-positron has enough energy to heat 1.3 billions of H₂O molecules for 1^o C.

 

 

Absolutely, you can describe it properties and behaviour, etc.

 

But that does not say what it "is"; and there seem to be people, like member Kramer, who want to know what an electron or mass or energy "is." And there is no reasonable answer to that.

[Sensei]

 

So far as I'm aware, there has never been a formula for charge, equivalent to E=mc² for mass, relating charge to energy.

 

That's older than Einstein equation..

 

E = Q*U (P=I*U multiplied by time)

1 J = 1 C * 1 V

so for Q=e

1.602e-19 J = 1.602e-19 C * 1 V (1 eV)

Kinetic energy that has single electron in 1 Volt potential difference.

 

E.K. = 1/2*m_e*v^2

so

v=SQRT(E.K.*2/m_e)

 

v = SQRT(1.602e-19*2/9.11*10^-31)=593,044 m/s

[studiot]

And where, pray, do you obtain your 1volt potential difference, if not from other charges?

[Enthalpy]

An electric charge only has energy by virtue of its interaction with another electric charge or charges.

 

An electric field has energy even in the absence of anything else. For instance light emitted by a distant star stores energy, possibly after the star's death, until our detectors receive it. Energy in the electric (and in the magnetic) field is the proper means to conserve energy, a useful idea since it's restored in the same amount that was consumed.

 

This electric or magnetic energy creates gravitation just as rest mass does. For instance gamma radioactivity carries mass away.

 

Then the electric field of a charged particle stores energy, whether an other charged particle feels the field or not. This energy is a part of the particle's rest mass, in the absence of any other particle.

 

Physicists are so much convinced of it that they were very bothered because the energy of a charged point particle is infinite, and introduced virtual electron pairs near the point to limit this electric energy to a finite amount.

Edited July 30, 2014 by Enthalpy

[studiot]

 

Then the electric field of a charged particle stores energy, whether an other charged particle feels the field or not.

 

I think you have that wrong.

 

Please show calculations to quantify this energy.

[Sensei]

Ultra high energy photons article mentions detection of gamma photons with energies above 10 EeV (16 Joules).

http://en.wikipedia.org/wiki/Ultra-high-energy_gamma_ray

 

Ultra high energy cosmic rays:

http://en.wikipedia.org/wiki/Oh-My-God_particle

 

Electron-positron pair production happens at billions lower energies (1.022 MeV photon) than these gamma photons have energy.

http://en.wikipedia.org/wiki/Pair_production

 

Ultra high energy photons (not only) are making shower of real particle-antiparticle pairs.

http://en.wikipedia.org/wiki/Extensive_air_shower

(so for gamma photon with >1.88 GeV, there might be created proton-antiproton pair)

 

Pair production is real. It has been observed in Cloud Chamber the first time in 40's XX century (and scientist got Nobel price for it).

Edited July 31, 2014 by Sensei

[studiot]

 

Ultra high energy photons article mentions detection of gamma photons with energies above 10 EeV (16 Joules).

http://en.wikipedia....nergy_gamma_ray

 

Ultra high energy cosmic rays:

http://en.wikipedia....My-God_particle

 

Electron-positron pair production happens at billions lower energies (1.022 MeV photon) than these gamma photons have energy.

http://en.wikipedia....Pair_production

 

Ultra high energy photons (not only) are making shower of real particle-antiparticle pairs.

http://en.wikipedia....sive_air_shower

(so for gamma photon with >1.88 GeV, there might be created proton-antiproton pair)

 

Pair production is real. It has been observed in Cloud Chamber.

 

 

If that was a comment on my posts,

 

I didn't say pair production was not real.

 

I actually said:

 

 

So far as I'm aware, there has never been a formula for charge, equivalent to E=mc² for mass, relating charge to energy.

 

An electric charge only has energy by virtue of its interaction with another electric charge or charges.

 

A mass has intrinsic energy by virtue of its mass.

 

 

Now field theories are only one possible explanation of the interaction - there are others.

 

However that is not the point.

 

Take a closed system with mass M.

 

There are measurable internal (radio) chemical process that can change M to M', the difference appearing as energy given by E = (M-M')c².

This can happen spontaneously without any interaction with the surroundings.

Radioactivity is such a process as are some chemical reactions.

 

This mass M or the end mass M' can also participate in energetic processes via other mechanisms that do not involve the partial conversion of the mass into energy.

 

 

So far as I am aware, a similar effect involving the partial convertion of an elementary charge into energy has never been observed, or proposed.

 

Charge conservation is rigidly maintained in all processes.

 

Charge can, however, participate in energetic processes via other mechanisms that do not involve the partial convertion of charge into energy.

 

Finally I believe I said charge can interact energetically with other charges.

 

Is not pair production or annihilation interaction with another charge and is not total charge preserved by these processes?

 

Edit, Apologies to Sensei who has let me know that his post was not a comment on mine but on something else. Hopefully he disn't find me too rude.

Edited July 30, 2014 by studiot

[Sensei]

Take a closed system with mass M.

If it's really closed, mass M should remain the same, regardless of radioactive decay of components inside.

 

Take for example (more or less closed) Earth- we have significant radioactivity in inner & outer core of Earth.

It doesn't mean that Earth is losing mass with time (as long as no neutrino is emitted to cosmic space)..

All (significant) energy decaying particles are carrying with them, are used to heat remaining particles.

 

There are measurable internal (radio) chemical process that can change M to M', the difference appearing as energy given by E = (M-M')c².

For more precise calculation, taking care of particular parent and daughter isotope, anybody can see mine signature..

 

This can happen spontaneously without any interaction with the surroundings.

(unfortunately) it's principle of radioactivity..

 

Einstein didn't like it, as it appears happening without a cause.

 

It's now known that we can at least stop unstable isotopes that have exclusive decay mode through electron capture from decaying by ionizing them permanently.

The first one (the lightest) isotope undergoing electron capture exclusively isotope is Beryllium-7.

Beryllium-7 + e- -> Lithium-7 + Ve + 0.861893 MeV

(that's what Chlorine-37 based neutrino detector is detecting the most often)

 

Radioactivity is such a process as are some chemical reactions.

I cannot agree with it.

Radioactivity is decay of unstable isotope nucleus. Transformation of heavier nucleus to lighter nucleus.

 

So far as I am aware, a similar effect involving the partial convertion of an elementary charge into energy has never been observed, or proposed.

Even on this forum it was proposed in speculation section by Arnaud Antoine ANDRIEU in his thread.

 

Charge conservation is rigidly maintained in all processes.

Otherwise we would have problem... If protons would start turning to antiprotons, and electrons to positrons (like Arnaud proposes), they would annihilate with regular matter..

 

Is not pair production or annihilation interaction with another charge and is not total charge preserved by these processes?

Without any doubt.

Edited July 31, 2014 by Sensei

[hypervalent_iodine]

!

Moderator Note

Kramer,

 

Your posts were off topic and your continued efforts to drive conversation towards discussion of your own ideas are considered derailment under the forum rules. I have split all of your posts and replies thereto into the trash. DO NOT attempt to derail this thread further by discussing this moderator note.

[studiot]

 

If it's really closed, mass M should remain the same, regardless of radioactive decay of components inside.

 

 

No, a definition of a closed system is that mass does not enter or leave, not that it remains constant.

 

 

Consider the system to be the following reaction

 

₂He⁴ + ₅B¹⁰ [math] \to [/math] ₆C¹³ + ₁H¹ + Q

 

Where Q represents 4.03 Mev of energy.

 

This can be compared with the measured mass differences as follows

 

₂He⁴ 4.00388 amu

₅B¹⁰10.01611 amu

 

Tot 14.01999 amu

 

₁H¹ 1.00815 amu

₆C¹³13.00751 amu

 

Tot 14.01566 amu

 

Difference = 0.00433 amu (loss of mass)

 

~Since 1 amu is equivalent to 931.2 Mev, this amounts to

 

4.032 Mev, which is usually

 

Here we have mass converted to energy.

 

I apologise for using old fashioned units but I studied this stuff a long time ago.

(Source of figures Semat : Atomic and Nuclear Physics 4th ED)

Edited July 31, 2014 by studiot

[Enthalpy]

[Responding to my: "Then the electric field of a charged particle stores energy, whether an other charged particle feels the field or not."]

 

 

I think you have that wrong.

 

Please show calculations to quantify this energy.

 

Well, that's absolutely standard electromagnetism. The volumic density of electrostatic energy is 0.5*E²/eps.

[studiot]

 

Well, that's absolutely standard electromagnetism. The volumic density of electrostatic energy is 0.5*E²/eps.

 

 

So you are stating that the total energy of any charge depends upon the volume of the surrounding ball of space, which in turn depends upon its radius all the way out to infinity, regardless of the presence or absence of any other charge?

Edited July 31, 2014 by studiot

[imatfaal]

 

So you are stating that the total energy of any charge depends upon the volume of the surrounding ball of space, which in turn depends upon its radius all the way out to infinity, regardless of the presence or absence of any other charge?

My memory of it is that you firstly invoke the work done to place one charge in free space (ie none), the second charge requires work against the first 1/(4 pi epsilon) *q1q2/r, the third against the first two etc. This can be seen as a sum, or using differential charges an integral over all space. Using a divergence vector equality and the divergence theorem this can be simplified to an integral of the surrounding surface. We can then give the work to produce an elextrostatic field over all space - the energy density of any portion of this field follows. 1/2 epsilon_zero |E|^2 is the energy density of an electrostatic field

[studiot]

 

My memory of it is that you firstly invoke the work done to place one charge in free space (ie none), the second charge requires work against the first 1/(4 pi epsilon) *q1q2/r, the third against the first two etc. This can be seen as a sum, or using differential charges an integral over all space. Using a divergence vector equality and the divergence theorem this can be simplified to an integral of the surrounding surface. We can then give the work to produce an elextrostatic field over all space - the energy density of any portion of this field follows. 1/2 epsilon_zero |E|^2 is the energy density of an electrostatic field

 

 

Yes, I agree that's the way it works, but that is not the point I have been trying to make.

 

So I will try again.

 

In an otherwise empty universe

 

Take 1kg of mass. I can calculate the total energy in Joules I would receive if I were able to convert that to energy, using the expression E=mc²

 

Now compare that with charge

 

In an otherwise empty universe

 

Take 1 coulomb of charge. As far as i know there is no formula, similar to the mass one, to replace all that charge with a specific quantity of Joules.

 

Worse, in the mass universe part only of the mass may be converted to energy, leaving a smaller amount of mass.

But in the charge universe there is I know of no corresponding process that can partly destroy charge.

 

Now in each universe if you introduce a second entity

 

In the mass universe there will be gravitational potential energy between the two masses.

 

In the charge universe there will be electric potential energy between the two charges.

 

So they are more similar here.

Edited July 31, 2014 by studiot

[barfbag]

A lot of good answers it seems but I'll add to the question a bit.

 

 

One aspect of Energy that seems odd to me is the whole "cannot be created or destroyed" aspects.

 

We are so used to seeing kinetic energies, etc., slow down and stop I almost expect energy to also stop or at least lose some of its potential.

 

But it goes on changing from one form to another.

 

It seems to defy logic to me.

 

If there is an easy rational then I plead I skipped that day in school, or my memory has another unresolved leak.

 

The conservation of energy in time just seems freaky.

Edited July 31, 2014 by barfbag