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Mass to light ?

  1. Feb 10, 2010 #1
    Mass to light ??

    Some mass is lost in a star when it burns hydrogen to form helium (
    4H = 1He at more than 7000 C is'nt) ? .. Any calculation how much is lost ??

    Even when u burn something which forms flame with are turning some mass into light right or wherelse is the light comming from (We all know flame emits light) ?

    by the way is'nt is breaking the law mass can neither be destroyed nor be created ?
  2. jcsd
  3. Feb 10, 2010 #2


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    Re: Mass to light ??

    This is more a "relativity" question than a "quantum" question. In the theory of relativity, [itex]E= mc^2[/itex]. There is no "conservation of energy" or "conservation of mass". Mass and energy are aspects of the same thing and there is a law of "conservation of mass/energy".
  4. Feb 10, 2010 #3

    Doc Al

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    Re: Mass to light ??

    Yes, even in chemical reactions (like flames) some small amount of mass is converted to energy.
    Since relativity, we realize that there's no such law as conservation of mass (except as an approximation). The real law is the conservation of mass-energy.
  5. Feb 10, 2010 #4
    Re: Mass to light ??

    Just to clarify - Burning is not the same process as nuclear fusion. Fusion releases energy (light) by 'breaking' the strong forces within an atom and messeing about with its nucleus, burning is releasing energy by putting all the atoms in the reaction into a lower energy state, by forming new bonds. Mass is not lost when burning something, it is just that the energy is changed into a different 'form'. I think.
  6. Feb 10, 2010 #5

    Doc Al

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    Re: Mass to light ??

    Whenever energy is released, some mass--however minuscule--is 'lost'. For practical purposes--certainly compared to nuclear reactions--you can think of mass being unchanged in chemical reactions like burning, but strictly speaking the mass does change.
  7. Feb 10, 2010 #6
    Re: Mass to light ??

    Even from a quantum perspective there is no loss here. Energy is being carried away in discrete quanta called photons in a series of reactions. Matter can be converted to energy, and energy is conserved in this cass, but MASS is a different issue entirely. This seems to be a simple semantic misunderstanding, and a question (which I don't know the answer to) about how much mass a star loses to ejecta (including light) over a specific period.

    A lot I'd say, given what I know about the size and nature of our lovely Heliosphere. It takes quite a while for the termination shock to occur after all, so that is a LOT of ejecta. I don't know how much is EM radiation, and how much is carried away as neutrinos and other particles, as well as elements through Carbon (while the star is 'alive' and assuming main sequence).

    Astra-Rudra If you want a look at the one possible area in which the essence of your question (the destruction of matter, not mass) take a look at The Information Paradox. That really adresses the problems of losing information in a Unitary system (which QM is), and the uproar such assertions create. Note even in this case mass is not conserved for the total system (the universe as a whole), even if the matter/energy is beyond an Event Horizon. Finally, remember your basic E=MC^2 is the proof for the EQUIVALENCE of MATTER and energy. Not Mass, which may or may not be the result of scalar fields.
  8. Feb 11, 2010 #7
    Re: Mass to light ??

    I understand what u mean but some mass is lost , u c the light (from flame) is emited .. its not a reflection , its a energy. So it has to be something . Light can't be created (conflicts law) so only thing possible thing is HEAT TO LIGHT or MASS TO LIGHT .
  9. Feb 11, 2010 #8
    Re: Mass to light ??

    Energy can be stored in the very act of holding atoms together - breaking the bonds releases it.
  10. Feb 11, 2010 #9
    Re: Mass to light ??

    No. Heat is not a field which is quantized. Photons in the IR spectrum = 'heat', so that is Electromagentic Quanta. Burning results in a plasma we clal fire, due to an oxidative process. The light you see every day, vs heat is the same thing. Heat is thermodynamic effect; the quanta carrying the actual energy isn't the "Heation", it's the PHOTON. Photons at Infra-Red wavelengths would be the ones you feel as heat more than any other.

    Mass is lost from the system 'log', but everything that aborbs a photon from that process is absorbing/re-emitting energy. The system which is CONSERVED, loses no MATTER/ENERGY, and momentum is conserved. Mass is a property of MATTER, which is equivalent as ENERGY.

    The title 'mass to light' is WRONG. It's "Matter to energy, which is equivalent and violates no conservation laws." Have you googled "Combustion" "Conservatin of energy" and "Stress-Energy Tensor", and "Electromagnetic Quanta"? If not, please do.
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