What type of energy is actually stored inside an atom?

[davLev]

What type of energy is actually stored inside an atom?
When an atom is split—such as in a nuclear explosion—it releases enormous energy, much of it in the form of gamma-ray electromagnetic radiation.
Given this, is it correct to say that the energy stored in the atom is fundamentally electromagnetic (EM) energy?
If not, how should we properly understand the nature of the energy that binds the nucleus and is released during fission?

 

[anuttarasammyak]

Yes. Ref. https://www.feynmanlectures.caltech.edu/II_01.html

 

[davLev]

Thanks.
If the energy stored inside an atom can ultimately appear as electromagnetic (EM) radiation when the atom is broken, does this imply that EM energy is required to form or “set” an atom in the first place?

 

[DaveC426913]

Thanks.
If the energy stored inside an atom can ultimately appear as electromagnetic (EM) radiation when the atom is broken, does this imply that EM energy is required to form or “set” an atom in the first place?

Energy is not a thing in itself; it is a property of a system, and it can change forms. A fast-moving atom has kinetic energy, which, if directed upward can be converted into potential energy, or if toward the ground, can be converted to heat energy, etc.

When an atom is split, the components often have less mass than when they were together, and the slight difference is released in various forms, sometimes as a small massive particle, sometimes as EM which, while massless, does have momentum.

Atoms are usually formed in the process of nucleosynthesis - a term you will want to look up. Sometimes the energy source is kinetic - if you bang two small nuclei together hard enough, sometimes they stick. That is an example of an atomic nucleus that has formed without the injection of EMR.

Ideally, others will come along and tidy up my sloppy explanations.

 

[anuttarasammyak]

EM energy is required to form or “set” an atom in the first place?

The electromagnetic repulsive force is an obstacle that must be overcome to achieve nuclear fusion. This condition is satisfied in the interior of stars.

 

[Astronuc]

When an atom is split—such as in a nuclear explosion—it releases enormous energy, much of it in the form of gamma-ray electromagnetic radiation.

When an atom of say Th, U, Pu and other transuranics fissions, much of the energy released is expressed as kinetic energy of the two nuclei which form two new atoms (fission products), two or more neutrons, prompt gammas, decay gammas, and a population of X-rays, visible light, and infrared as ionized atoms interact with each other and recombine with electrons. There are some photonuclear reactions.

A nuclear force binds the protons and neutrons (nucleons) in opposition to the electromagnetic (Coulomb) repulsion.

 

[sbrothy]

Incidentally, I read that India is pursuing Thorium fission reactor energy due to it's large deposits of Thorium ore. Unfortunately, it an immature technology but the current mature technology was pursued due to the fact that the US needed stockpiles of Plutonium for bombs and now we're stuck with that darn stuff!

Nuclear Power Reactors: A Study in Technological Lock-in

Role of thorium in the Indian nuclear power programme.

Utilisation of thorium in reactors.

EDIT: Heck, we have to throw most of the Uranium rods away as reprocessing it will just leave us with more deadly nasty radioative stuff.

 

[davLev]

Thank you all for the explanations.

I would like to clarify an important point in my question:
we are explicitly discussing particle creation in the absence of any pre-existing matter.
In such a scenario, concepts like kinetic energy of particles are not applicable, because kinetic energy requires matter in motion.

The only available physical entity in this discussion is electromagnetic energy itself (fields).

Therefore, my question is not about converting kinetic energy of matter into radiation, but rather:

Can electromagnetic energy alone, without any nearby matter, be converted into real particles?

This clarification removes kinetic energy from the discussion entirely and focuses solely on EM energy as the initial and only ingredient.

In the following article it is stated:

Yes. Ref. https://www.feynmanlectures.caltech.edu/II_01.html

We can write the force F on a charge q moving with a velocity v as

F=q(E+v×B).(1.1)​

We call E the electric field and B the magnetic field at the location of the charge.

if a region of space contains only electromagnetic fields, with no pre-existing matter, can that electromagnetic energy be converted into real particles?
Specifically:

1. Can electromagnetic field energy alone give rise to an electron–positron pair, without using any external matter as a catalyst?
2. Once such particles exist, can their kinetic energy together with electromagnetic energy, still without introducing any external matter, be sufficient in principle to form:
   
   • heavier particles (such as quarks and gluons),
   • composite particles (protons, neutrons),
   • and ultimately a real hydrogen atom?

My intention is to understand whether pure field energy, starting from electromagnetic fields only, can in principle bootstrap its way into stable matter through successive energy conversions — without assuming any initial material substrate.

 

[PeroK]

Thank you all for the explanations.

I would like to clarify an important point in my question:
we are explicitly discussing particle creation in the absence of any pre-existing matter.
In such a scenario, concepts like kinetic energy of particles are not applicable, because kinetic energy requires matter in motion.

The only available physical entity in this discussion is electromagnetic energy itself (fields).

In classical physics, there is a distinction between charged particles and electromagnetic fields. Moreover, the mass of a closed system is conserved (doesn't change over time). Technically, mass in this context is the rest mass of the constituent particles.

In Special Relativity, the mass of a system is not simply the rest mass of its constituent particles. For example, the mass of a hydrogen atom is less than the mass of an isolated proton plus the mass of an isolated electron. When a hydrogen atom is formed, energy is released in the form of electromagetic radiation (photon). That's a simple example that rest mass is a form of energy.

More generally, rest mass is not conserved in particle collisions. High-energy collisions of protons, say, can produce heavier particles. This is what takes place at CERN and other particle colliders:

https://en.wikipedia.org/wiki/Large_Hadron_Collider

The reverse process can also happen, where particles with non-zero rest mass (e.g. an electron and positron) can annihilate each other and produce electromagnetic radiation (in the form of two or more photons). See for example:

https://en.wikipedia.org/wiki/Electron–positron_annihilation

 

[PeroK]

PS and electromagetic radiation can produce an electron-positron pair. See, for example:

https://en.wikipedia.org/wiki/Breit–Wheeler_process

 

[davLev]

Thank you for the clarification
I fully agree with the points about mass–energy equivalence in special relativity and with the examples you gave (hydrogen binding energy, particle creation in colliders, and annihilation into photons).
However, I would like to emphasize the specific scope of my question:

• I am not disputing that rest mass is a form of energy or that mass–energy conversion occurs in particle collisions.
• I am also not relying on existing massive particles (such as protons accelerated at CERN) as the starting point.

My focus is more fundamental:
Would you agree that a sufficiently strong, continuous electromagnetic field — even in the absence of photons and pre-existing matter — can, in principle, give rise to real particles?
This is commonly discussed in quantum electrodynamics under vacuum pair production (e.g., the Schwinger mechanism), where energy stored in an electromagnetic field can be converted into massive particle–antiparticle pairs without requiring matter or collisions as an initial substrate.
My question is therefore conceptual in nature, concerning EM field-to-matter conversion, rather than the practical engineering of particle accelerators.

 

[renormalize]

Would you agree that a sufficiently strong, continuous electromagnetic field — even in the absence of photons and pre-existing matter — can, in principle, give rise to real particles?

Yes, I definitely agree with that statement, since what we now called the "Schwinger effect" (https://en.wikipedia.org/wiki/Schwinger_effect) has been discussed from 1931 to the current day. So I'm curious: why do you ask?

 

[davLev]

Thank you — I appreciate the confirmation.

The reason I am asking is to clarify a conceptual point in the discussion:
that electromagnetic field energy alone, even in the absence of photons and pre-existing matter, can in principle act as a primary source for matter creation.

My interest is not in the historical or experimental status of the Schwinger effect itself, but in its implication: namely, that EM fields are not merely passive mediators between particles, but can function as an energetic substrate from which real particles emerge.

Once vacuum pair production from EM fields is accepted, the natural next question is how far this process can proceed in principle within the Standard Model.
I would therefore like to ask whether you agree with the following chain of reasoning:

• It is well established that sufficiently energetic photons can produce fermion–antifermion pairs. At high enough energies, photon–photon interactions can also produce quark–antiquark pairs, subject to Standard Model constraints.
• A key point is that quarks cannot exist without color fields. When a quark–antiquark pair is produced, the QCD (gluon) field necessarily appears as part of the same quantum process, enforcing confinement. In this sense, the strong field does not need to pre-exist independently.
• Given sufficient energy and suitable conditions, confined quarks can form:
  
  • mesons (q + q̄),
  • and, through further interactions, baryons (q + q + q), such as the proton (uud).
• The proton’s mass (~938 MeV) is dominated not by bare quark masses, but by QCD field energy, indicating that while electromagnetic energy may initiate particle production, the strong interaction becomes the dominant energy reservoir once quarks exist.
• From there, standard interactions apply:
  
  • baryons can bind into nuclei via the residual strong force,
  • electrons can bind to protons electromagnetically,
  • and stable atoms (e.g., hydrogen) can form once relative energies are sufficiently low.

Therefore, would you agree that within known physics there appears to be no fundamental prohibition against a chain that begins with pure electromagnetic field energy and proceeds, step by step, to stable matter — without assuming any initial material substrate?

 

[renormalize]

Therefore, would you agree that within known physics there appears to be no fundamental prohibition against a chain that begins with pure electromagnetic field energy and proceeds, step by step, to stable matter — without assuming any initial material substrate?

Sure, but what's your point? Rather than EM energy, the gravitational energy of the big bang is much more likely to have produced the particles of the standard model. See for example:
Cosmological gravitational particle production and its implications for cosmological relics
Abstract:
"Cosmological gravitational particle production (CGPP) is the creation of particles in an expanding universe due solely to their gravitational interaction. These particles can play an important role in the cosmic history through their connection to various cosmological relics including dark matter, gravitational wave radiation, dark radiation, and the baryon asymmetry. This review explains the phenomenon of CGPP as a consequence of quantum fields in a time-dependent background, catalogs known results for the spectra and cosmological abundance of gravitationally produced particles of various spins, and explores the phenomenological consequences and observational signatures of CGPP."

 

[anuttarasammyak]

@davLev Why we observe more electrons than positrons would become your question then.

 

[davLev]

Thank you.

Once we accept that pure electromagnetic field energy can, in principle, give rise to real particles (e.g. via strong-field QED and related processes), and that subsequent Standard Model interactions can lead step by step to bound states and atoms, I am interested in the conceptual implication of this chain.

My point can be stated as follows:

If electromagnetic field energy can act as the initial source from which particles and atoms ultimately emerge, then electromagnetism plays a uniquely foundational role in the energy budget of matter formation.

This perspective helps explain several well-established observations:

When nuclei transition or are disrupted, a significant portion of the released energy appears as electromagnetic radiation (e.g. gamma rays).

Much of the mass of hadrons arises from field energy rather than bare particle masses.

All quantum fields exhibit fluctuations, and different interaction fields govern how energy is stored, confined, and redistributed.

Bound systems across scales (atomic, nuclear, gravitational) obey formally similar inverse-square or orbital relations, reflecting general principles of field-mediated interactions rather than identical forces.

Electromagnetism appears to be the only interaction that can exist as freely propagating field energy in empty space and directly initiate the conversion of energy into matter. Once particles exist, the strong and weak interactions necessarily govern their internal structure and stability, while gravity acts on the resulting energy–momentum distribution.

In this framework:

A photon is an excitation of the EM field.

Fermions and quarks are excitations of their respective quantum fields, whose creation can be triggered by sufficiently concentrated energy.

Gluons are excitations of the SU(3) color field that necessarily accompany quarks, governing confinement and hadron structure.

Thus, would you agree that electromagnetism may be viewed as the primary operational gateway through which energy first becomes matter, making it a strong candidate for the most fundamental enabling interaction in nature?
If electromagnetic fields were entirely absent, what might be the outcome?

 

[PeterDonis]

If electromagnetic field energy can act as the initial source from which particles and atoms ultimately emerge

Not the "initial source"--the electromagnetic field energy itself didn't appear out of nowhere.

According to our best current models, our best candidate for an "initial source" of all the matter and energy in the universe is the inflaton field--the field whose "false vacuum" state caused inflation. At the end of inflation, this field gave up its energy to all of the Standard Model fields--not just the electromagnetic field. Indeed, the EM field we know today didn't even exist then, since it only came into being after the electroweak phase transition.

electromagnetism plays a uniquely foundational role in the energy budget of matter formation.

No, it doesn't, because you're not considering the whole picture. See above.

This perspective helps explain several well-established observations:

No, it doesn't. Those observations are best explained by the entire Standard Model, not just the little piece of it you are looking at.

\When nuclei transition or are disrupted, a significant portion of the released energy appears as electromagnetic radiation (e.g. gamma rays).

But the strong and weak interactions are also involved; it's not just EM.

Much of the mass of hadrons arises from field energy rather than bare particle masses.

Strong interaction field energy, not EM field energy.

All quantum fields exhibit fluctuations, and different interaction fields govern how energy is stored, confined, and redistributed.

Sure, but EM is only one of them (and, as above, it only exists in the form we know it at energies below the electroweak phase transition energy).

Bound systems across scales (atomic, nuclear, gravitational) obey formally similar inverse-square or orbital relations

No, they don't. Only the EM and gravitational interactions have inverse square laws in the low energy limit. The strong and weak interactions do not.

Do you agree that If electromagnetic fields were entirely absent, no known stable atoms, chemistry, or complex matter as we observe it could exist?

Sure, but you could say the same about the strong and weak interactions. There's nothing that picks out EM as being special here.

Electromagnetism appears to be the only interaction that can exist as freely propagating field energy in empty space

No, gravitation also can.

and directly initiate the conversion of energy into matter.

No, there are strong and weak interactions that start with only gauge bosons and end up with "matter".

would you agree that electromagnetism may be viewed as the primary operational gateway through which energy first becomes matter, making it a strong candidate for the most fundamental enabling interaction in nature?

No. See above.

 

[PeterDonis]

Thread closed for moderation.