The origin and end of photons

Discussion in 'Physics & Math' started by Magical Realist, Jul 4, 2021.

  1. Magical Realist Valued Senior Member

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    Can anyone explain to me, possibly in layman's terms, where photons come from, and where they go when they disappear? Tks in advance..
     
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  3. mathman Valued Senior Member

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

    read this.
     
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  5. DaveC426913 Valued Senior Member

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    Photons - packages of electromagnetic energy - are
    - emitted when an electron in an atom jumps to a lower energy orbital.
    - absorbed by an atom's electron, making it to jump to a higher energy orbital.
     
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  7. exchemist Valued Senior Member

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    That's the main explanation for photons in the visible, UV and X-ray regions.

    But in the IR it tends to be when molecules with a dipole change vibrational or rotational quantum state.

    And in the γ-ray region it is changes of quantum state in the atomic nucleus.

    And then there are the radio-frequency photons generated and absorbed by the acceleration of electrons in the conductors of radio antenna.
     
  8. Q-reeus Valued Senior Member

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    According to standard QED, they don't 'go anywhere'. They simply cease to exist. But not without transferring their energy & momentum elsewhere.
    Thus a photon incident on a mirror doesn't bounce back as the same photon like a ball would. Incoming photon is annihilated. Followed by an outbound photon that is created. The net process delivering a very small 'kick' to the mirror - origin of radiation pressure.
     
  9. C C Consular Corps - "the backbone of diplomacy" Valued Senior Member

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    Problem is that few want to make an ontological commitment to what's "really going on" with respect to photons and particles in general. (It would just be dogmatically stumping for a rigid philosophical orientation, anyway.) So the matter is arguably left as an epistemological haze of multiple perspectives or competing possibilities.

    While the Standard Model (which subsumes QFT, electroweak theory, chromodynamics, etc) is the go-to practical construct of today, the future of fundamental physics depends upon either unseating it or radically supplementing it to avoid the discipline becoming stagnant (i.e., loss of job security or reduction in funding, number of employees).

    So while there is genuflection to the monarch of the Standard Model and its pronouncements, all the while they're also plotting a coup.


    What, exactly, is a photon?
    https://spie.org/news/photonics-focus/novdec-2020/what-exactly-is-a-photon

    With new experiments and technologies, physicists have shown they can control individual photons with unprecedented precision. But the enigmatic elementary particle still hides its true colors.
    - - - - -

    What Is a Particle?
    https://www.quantamagazine.org/what-is-a-particle-20201112/

    It has been thought of as many things: a pointlike object, an excitation of a field, a speck of pure math that has cut into reality. But never has physicists’ conception of a particle changed more than it is changing now.
    - - - - -

    How Do Quantum Fields Create Particles?
    https://www.forbes.com/sites/starts...ethan-how-do-quantum-fields-create-particles/

    So how do we get quantum particles with the properties we do? Three things come together:

    We have the laws of quantum field theory, which describe the fields permeating all of space that can be excited to different characteristic states.

    We have the mathematical structure of the Standard Model, which dictates the allowable combinations of field configurations (i.e., particles) that can exist.

    We have the fundamental constants, which provide the values of specific properties to each allowable combination: the properties of each particle.

    And there may be more. The Standard Model may describe reality extremely well, but it doesn't include everything. It doesn't account for dark matter. Or dark energy. Or the origin of the matter-antimatter asymmetry. Or the reasons behind the values of our fundamental constants.

    The Standard Model only provides the allowable configurations we know of. If neutrinos and dark matter are any indication, there ought to be more. One of the prime goals of 21st century science is to find out what else is there. Welcome to the cutting-edge frontier of modern physics.

    - - - - - -

    Are quantum fields real?
    https://www.forbes.com/sites/startswithabang/2018/11/17/ask-ethan-are-quantum-fields-real/

    [...] It means that the electron isn't a particle at all. It's not something you can put your finger on and declare, "the electron is here, moving with this particular speed in this particular direction." You can only state what the overall properties are, on average, of the space in which the electron exists.

    [...] This is where the idea of 12 fermion fields and 12 boson fields come from. These fields are excitations of the underlying theories (the Standard Model) that describe the known Universe in its entirety, and include:

    (1) The six (up, down, strange, charm, bottom, top) quarks, and their antiquark counterparts,
    (2) The three charged (electron, muon, tau) and three neutral (electron neutrino, muon neutrino, tau neutrino) leptons, and their antimatter counterparts.
    (3) The eight gluons (because of the eight possible color combinations),
    (3) The two weak (W-and-Z) bosons,
    (4) The one electromagnetic (photon) boson,
    (5) And the Higgs boson.

    [...] Particles, antiparticles, and all sorts of excitations of the fields are constantly being created-and-destroyed. Reality is fundamentally different from our classical picture of a smooth, continuous, well-defined Universe. Although it's true that these quantum fields began as a mathematical construct, they describe our physical, observable reality more accurately than any other theory we've concocted. They allow us to make incredibly precise predictions about what the results of any experiment involving the quanta of the Standard Model will yield: predictions that have been borne out by every experiment sensitive enough to test them.

    The Universe may not be an intuitive place, but as far as any physical theory can call itself reflective of reality, QFT has no equal in terms of its power. As long as physics remains an experimental science, this will be the standard that any candidate theory will have to supersede.
     
    Last edited: Jul 5, 2021
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  10. exchemist Valued Senior Member

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    I find you unduly cynical about the motives of these researchers. There do remain unsolved issues in quantum physics. It is not just a giant job creation scam for academics.
     
  11. Magical Realist Valued Senior Member

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    Thanks for all your answers. Much to contemplate there.
     
  12. C C Consular Corps - "the backbone of diplomacy" Valued Senior Member

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    Legit reasons were referenced in part of the quotes (repeated below). Thus, to avoid redundancy, my role in that area was to add something snarky and conducive to disillusioning a Polyanna passerby from naïvely accepting an idealized conception of science as being totally free from human self-interests.

    Please Register or Log in to view the hidden image!


    - - - - - -

    Ethan Siegal: And there may be more. The Standard Model may describe reality extremely well, but it doesn't include everything. It doesn't account for dark matter. Or dark energy. Or the origin of the matter-antimatter asymmetry. Or the reasons behind the values of our fundamental constants.

    The Standard Model only provides the allowable configurations we know of. If neutrinos and dark matter are any indication, there ought to be more. One of the prime goals of 21st century science is to find out what else is there. Welcome to the cutting-edge frontier of modern physics.
     
  13. arfa brane call me arf Valued Senior Member

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    7,184
    I think it's patently obvious that photons are 'quantum objects' which aren't yet fully understood.

    Evidence for this lack of knowledge is the continual announcement by researchers of new results in optonics. If we had a full model of photons these results wouldn't be unexpected; research would be a matter of designing an experiment to test a prediction, there would be no surprises.
     
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  14. Magical Realist Valued Senior Member

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    I think there is more mystery in the photon than in all the equations of quantum field theory.
     
  15. QuarkHead Remedial Math Student Valued Senior Member

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    As one who obviously knows QFT and its mathematics, and still finds it "mysterious", tell us why you think the electromagnetic energy quantum is "more mysterious"
     
  16. irk Registered Member

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    9
    There is a pop book with interesting title Photons The History and Mental Models of Light Quanta
    Yes, we are operating with mental models what these beasts are and thus sometimes they are particles with zero mass,
    sometimes they are waves, sometimes they are quanta of electromagnetic energy, sometimes they are excitations of universal photon field.
    On a sophisticated level the mental models reach arcane math. But all of these are only mental models built up with specific human semantics and
    picking up just shadows of quantum reality.
     
  17. Write4U Valued Senior Member

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    17,374
    A thought.
    Perhaps this is the purest state of Chaos that exists. It is here self-organization begins, patterns forming within a cauldron of elementary values.

    Perhaps this is David Bohm's "pure state of energy", from which a hierarchy of mathematical orderings emerge. The chaotic field where Implicate patterns are formed and eventually emerge as the Explicate in reality.

    David Bohm 1917-1992
    This interview with David Bohm, conducted by F. David Peat and John Briggs, was originally published in Omni, January 1987
    ......more

    http://www.fdavidpeat.com/interviews/bohm.htm

    Plasma oscillation
    https://en.wikipedia.org/wiki/Plasma_oscillation

    Any relationship to the discussion?
     
  18. irk Registered Member

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    9
    While one can claim that everything is related to everything it seems this has no relation to the discussion.
     

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