How does a photon carry energy in itself?

Discussion in 'Physics & Math' started by Saint, Feb 8, 2022.

Thread Status:
Not open for further replies.
  1. Write4U Valued Senior Member

    Messages:
    18,777
    Does the spacetime stretching not compass the entire 3D volume

    Question : If spacetime stretches does that not also stretch everything within it? And if so, does the stretching create an imbalance or will everything remain in the same frame of reference as when spacetime is smaller?

    Would we become aware that everything is stretching, including ourselves?
    And speaking of frequencies, would frequencies of all wave functions alter in a stretching spacetime.
     
  2. Google AdSense Guest Advertisement



    to hide all adverts.
  3. arfa brane call me arf Valued Senior Member

    Messages:
    7,731
    Cosmic expansion is seen in the redshift of distant galaxies. Redshift is exactly the change in frequency of photons from such distant sources.
    The redshift therefore gives a kind of metric (distance measurement).
    Yes, but only over very large distances, much greater than say, the distance from our sun to the centre of our galaxy or any galaxies in the local group. It has practically no observable influence locally.
    All the galaxies at the same redshift distance are comoving, so no. The galaxies aren't stretched, the distance between them and us is.
    No, and no.
     
  4. Google AdSense Guest Advertisement



    to hide all adverts.
  5. arfa brane call me arf Valued Senior Member

    Messages:
    7,731
    Those electromagnetic oscillations in an electronic circuit propagate away from the circuit into the space around it in all directions.

    In a conductor electrons don't have to move very far to generate a 'signal'. The currents in a circuit don't need to move at the same scale as say a pendulum. This is because the electromagnetic fields generated by an oscillating current are many orders of magnitude greater than the gravitational fields of a pendulum oscillating.

    That means detecting gravitational signals is way harder than detecting electromagnetic signals.

    But how do photons carry energy, isn't really the question. The question should be how is photon energy related to photons propagating.
     
    river likes this.
  6. Google AdSense Guest Advertisement



    to hide all adverts.
  7. Saint Valued Senior Member

    Messages:
    4,631
    The Sun provides the Earth energy, right?
    Light from the Sun, which is photon, carry heats to the Earth.
    How the particles of photon carry energy?
     
    river likes this.
  8. exchemist Valued Senior Member

    Messages:
    11,468
    Any wave carries energy, by virtue of the fact that a wave is a travelling displacement of a medium from its equilibrium position.

    To displace the medium you have to do work on it (which is energy), and that energy is then carried by the wave as it travels.

    In the case of light, it is a travelling disturbance in the electromagnetic field.

    Light gives up its energy when it is absorbed. In the case of visible light*, when this happens it gives up its energy to an electron in the absorbing material, causing it to enter an excited (higher energy) state. This energy may then be further converted within the absorbing material in various ways, usually ending up as heat.

    *In the case of EM radiation that is in other ranges of the spectrum, it may not be an electron but some other feature of matter that is excited.
     
    Yazata likes this.
  9. arfa brane call me arf Valued Senior Member

    Messages:
    7,731
    A very common misconception about electrons is that a current is responsible for the transfer of energy to a circuit or say an electric motor.

    If that was true you would have an alternating positive/negative flow of energy from an alternating current.

    What actually happens is energy is transmitted by the electric and magnetic fields in the space around a current flowing back and forth in a conductor.

    In the case of photons the alternating fields underline this; the energy of photons doesn't depend on their speed (or velocity) through a vacuum or a material.

    Their energy only depends on how fast the electromagnetic fields alternate together.

    If you think that's wrong you need to explain the photoelectric effect in some alternative way. Ok?
     
    river likes this.
  10. James R Just this guy, you know? Staff Member

    Messages:
    37,550
    arfa brane:

    If you think that the group of people consisting of those who have a good understanding of the concept of energy is a special group, then I guess I am. You can call us "energy experts" if it makes you happier.
    Not particularly. If you asked nicely, maybe I'd offer you one. Mind you, I have posted on this topic many times in the past on this very forum. Perhaps you just missed all of those previous posts.
    He was right in saying that energy is just a number!
    Now you're getting it!
    What is "transferred", exactly? As far as I can tell, you take a number from one column in your energy accounting ledger and you move it to another column, more or less. There's no "energy stuff" being physically moved from one place to another.
    Essentially, the different "forms of energy" that you mention are just separate columns in an energy accountacy ledger. The particular numbers and the ways they are calculated correspond, of course, to actual physical processes that are going on in various ways. For example, consider kinetic energy, the "energy of motion". The "stuff" is the molecules doing their thing. But the energy is just a number we associate with that molecular motion: we calculate E=(1/2)mv^2 for a molecule and get a number. We call that number the molecule's "kinetic energy".
    Information is a physical thing? I think that information is a conceptual thing. In what sense is information physical?
    For instance, tell me how the information content of this post you're reading manifests itself physically.
    None of the physical objects you mention are numbers and you know that I never claimed they were. I was talking about energy, remember?
    Lots of numbers in physics have units. Having units, by itself, doesn't turn a concept into some kind of physical substance. Take a different example: the charge on an electron. It is a number that has units of Coulomb, for instance. Does that mean that charge is a substance that can exist independently of the electron it is associated with? No. Both the electron's charge and its energy (whatever kind of energy you like) are numbers we associate with the electron. They are useful numbers, but numbers nonetheless.
    There are lots of numbers with physical units and lots of numbers without them. All of them are numbers (or "just numbers", if you prefer). My point was/is that it is a mistake to start imagining that numbers are the same as physical objects or substances, which is what a lot of people do with energy (in particular). Numbers are concepts. If I have 3 sheep, the "threeness" is a property of the group of sheep - a conceptual property. There's nothing physically "threeish" about the sheep. We can't extract the threeness and bottle it. It's the same with the energy of the sheep.

    I hope this helps clarify things for you.
     
    Last edited: Mar 31, 2022
    Write4U and exchemist like this.
  11. Write4U Valued Senior Member

    Messages:
    18,777
    Thank you for that excellent clarification. Sciforums at its best!
     
  12. arfa brane call me arf Valued Senior Member

    Messages:
    7,731
    So heating some water to make a coffee, is taking a number from one column and moving to another column?
    But there's water, and there's heat from a source of heat; the water gets heated. Where are the two columns you say I need, so I can heat up the water?

    Or say I start the engine in my car, it starts because a battery has electrical energy, and because the fuel has chemical energy. Where are these columns you mention? Why does your explanation seem so completely useless and counterfactual? I've never seen any of these columns. Quite likely that's because your idea is too simplistic. A five year old might be taken in, I guess. But five year olds grow up eventually.

    Perhaps you might too, one day.
     
    Last edited: Mar 31, 2022
  13. arfa brane call me arf Valued Senior Member

    Messages:
    7,731
    Why does this number not exist independently of the electron? What do you think it means, when there are numbers that are completely independent of physics, that really are just numbers and nothing else?
     
  14. arfa brane call me arf Valued Senior Member

    Messages:
    7,731
    Well, that's complete bullshit James, sorry. You're a physics joke.
     
  15. arfa brane call me arf Valued Senior Member

    Messages:
    7,731
    Then why do you make that mistake?
    Yes James; information is physical. I see you have some catching up to do.

    If information was a concept, how would you transmit it or store it? Why would someone, as you just did, ask "how the information content of this post you're reading manifests itself physically". That's pretty asinine, you must actually be an idiot.

    Good job. I hope you stay ignorant and never bother to question your knowledge of . . . anything at all. God help us all if you do.
    You're an Aussie, right? That's pretty obvious too, you goddam moron.

    Richard Feynman wasn't an idiot, but he probably didn't understand information in the modern sense either. Computer Science was in its infancy in the 1950's, in much the same way your understanding of it is.
     
    Last edited: Mar 31, 2022
  16. arfa brane call me arf Valued Senior Member

    Messages:
    7,731
    It isn't "just" a conceptual property, you idiot.
    The concept is in fact, information. Or I guess you could have a try at explaining how the concept exists in a brain without the three sheep, or three of anything (physical).
    And "we" can't explain how the statement "three sheep" doesn't look like a bottle, I guess. It does contain, um, information though doesn't it?

    Unless of course you don't have a big enough brain . . .
     
  17. arfa brane call me arf Valued Senior Member

    Messages:
    7,731
    Really, the simple answer to the OP question is thus:

    Photons carry energy from place to place for the apparently simple reason that they also carry information from place to place.

    Except that information isn't really simple.
    Information has entropy, and that concept isn't simple. If it was it would be as easy as . . . counting sheep.

    I know there are some people (some of them are moderators here, but I'm not naming names) who don't appear to believe that they might still learn something.

    If you happen to believe you aren't in that group, I can suggest studying information entropy. Also some category theory, maybe constructor theory.

    Think on this one though. The concept of information, or the concept of numbers, are impossible without brains in the universe.

    A concept in your brain/mind is information, it's encoded because it has to be. Concepts in human or other animal brains would not exist if life didn't exist.
    Would numbers still exist? Would information that could be interpreted as numbers still exist? Would communication or computation exist?

    That's what I think you could call an open question.

    Thanks James for opening that door, and allowing me to demonstrate how ignorant you actually are.
     
    Last edited: Apr 1, 2022
  18. Write4U Valued Senior Member

    Messages:
    18,777
    Yes, the concept is. The functional exchange of information is very much possible without the antropomorphic concept.
    The entire field of chemistry is based on the exchange of elementary information.
    Yes, if you believe that people conceptualize reality.
    But a concept is not a physical thing at all. It is an emergent imaginary quality of neural information processes.
     
  19. arfa brane call me arf Valued Senior Member

    Messages:
    7,731
  20. Write4U Valued Senior Member

    Messages:
    18,777
    And that abbreviation conveys physically conceptual information?
    That was a conceptual imaginary motivation. I don't think it helped your argument in a positive way.
     
  21. James R Just this guy, you know? Staff Member

    Messages:
    37,550
    arfa brane:

    No. When you heat water, you cause the water molecules to move around, rotate and vibrate more, by doing something that causes those molecules to jiggle around. In an electric kettle, for instance, the water is placed in contact with some hot metal, and the metal atoms physically bump into the neighbouring water molecules. Notice that, in this description, the word "energy" does not appear.
    If you like, you can open your energy ledger and describe the process as some electrical energy being moved to the column corresponding to kinetic energy in the heating element, then moved to the column corresponding to kinetic energy of the water molecules. The temperature of the water is a measure of the average kinetic energy of the water molecules. To find it, you could, in principle, look at how fast the water molecules are moving and then grab your calculator to fill in the "kinetic energy" column in your energy ledger. Then, by the miracle of averaging, combined with some calibration, you get a temperature reading out. Alternatively, you could just stick a (calibrated) thermometer in the water.
    Those columns are the ones you're labelling "electrical energy" and "chemical energy". The physical processes that start your car are not the same thing as the energy numbers you write down.
    There are numbers in physics and numbers outside (e.g. I have 3 sheep).

    I can bottle a sheep (if I have a large enough bottle), but I can't bottle the number "3".

    You can settle our little dispute very quickly right now, if you can produce a bottle of "pure" energy for me. Can you do that, or not? If not, why not?
    Ah, an attempt at argument by ad hominem insult. Poor show, arfa brane. Can't you do any better than that?

    What happened to you, man? I always thought you were more capable than this.
    Please try to keep up. Re-read what I wrote.
    If I get out my HB pencil and write down my name, say, then the information is "stored" in the graphite markings on the paper. The graphite and paper is the physical storage medium of that information. But by themselves, graphite markings on paper are just that. The information in my name is entire conceptual: the idea that those markings represent sounds in a language, that this particular combination of phonemes represents a proper name, etc. All of that is entirely in your head; none of it is in the graphite.
    Clearly, you're hopelessly confused and the only refuge you can find lies in insults. Try to come up with an actual argument or two. That would be more constructive. Also, just as a hint: if you expect somebody to converse politely with you, you ought to try practising some politeness yourself. Otherwise you come across as a crass bore.
    Personal insult not enough for you? Now you feel like you need to insult an entire nation of people? Does that make you feel better about your failings?
    Feynman, as it turns out, was a very bright guy. He gave a very interesting talk about miniaturisation and information storage, years ahead of its time. You should look it up. You might learn something.
     
    Last edited: Apr 1, 2022
  22. arfa brane call me arf Valued Senior Member

    Messages:
    7,731
    I don't think your earlier post helped either.
    In any way.

    I suppose I should ask, although the answer seems to be readily apparent, have you done any formal study of information theory, or of neurological science?

    And, do you realize you're saying you know something that neither of those subjects predicts or theorises, in any way shape, or form?

    Your idea is "just" an idea with no evidence or research to support it?

    Otherwise known as a speculation. One that seems to be based on imagination?
     
    Last edited: Apr 1, 2022
  23. Write4U Valued Senior Member

    Messages:
    18,777
    And here I thought that James just confirmed my understanding of the subject of conceptualization.
    I agree with that. Don't you?

    Tegmark had a similar analogy. His wife's name was inscribed in his wedding ring and that represented a durable form of information. However, if he had inscribed his wife's name in a puddle of water, the information would have been lost immediately. In any case the concept that is represented in either activity is "marriage". An exchange of vows!
    Nothing material about that exchange.
     
    Last edited: Apr 1, 2022
Thread Status:
Not open for further replies.

Share This Page