Does binding energy mean energy has a mass?

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Discussion Overview

The discussion revolves around the relationship between binding energy and mass defect in atoms, specifically whether binding energy implies that energy has mass. Participants explore the implications of Einstein's equation E=mc² and its interpretations in the context of mass-energy equivalence.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants suggest that the mass defect in an atom is due to binding energy, questioning if this means binding energy contributes to the atom's mass and has mass itself.
  • One participant asserts that energy and mass are fundamentally the same, proposing that mass is a compact form of energy and that energy can be considered to have mass.
  • Another participant challenges the notion that energy has mass, arguing that while mass is proportional to energy, this does not imply that energy itself possesses mass.
  • Some participants reference the equation E² = m²c⁴ + p²c² to argue that adding energy without increasing momentum results in an increase in mass, suggesting that energy does have mass in this context.
  • There is a discussion about the gravitational behavior of photons, with one participant questioning how gravity affects photons if they are massless, while another clarifies that gravity does not change the speed of light but can affect its momentum.
  • One participant offers an alternative formulation of mass defect in terms of binding energy, suggesting that it contributes to the total mass of the atom.

Areas of Agreement / Disagreement

Participants express differing views on whether energy has mass, with some asserting that it does while others maintain that energy is proportional to mass but does not possess mass itself. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Participants reference various interpretations of mass-energy equivalence and the implications of binding energy, but there are unresolved assumptions regarding the definitions of mass and energy in different contexts.

brandy
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Is the Mass Defect in the atom due to the Binding Energy and does this account for that small amount of mass?
does this mean that it contributes to the atom's mass and has a mass itself?
 
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Yes, of course. E= mc^2.
 
how? energy=mass * speed of light ^2
big woop. i don't get it.
mass is proportionately equal to energy but this doesn’t mean energy has mass.
elaborate please.
 
brandy said:
how? energy=mass * speed of light ^2
big woop. i don't get it.
mass is proportionately equal to energy but this doesn’t mean energy has mass.
elaborate please.

One could say that mass is nothing but an incredibly compact bundle of energy. Mass is how we deal with energy in the frame of reference of gravity. Energy IS mass, mass IS energy.
 
brandy said:
how? energy=mass * speed of light ^2
big woop. i don't get it.
mass is proportionately equal to energy but this doesn’t mean energy has mass.
elaborate please.

how do you not get it, for small amounts of mass the energy is large so it takes equally large amounts of energy to have enough mass to notice yes energy has mass.
 
brandy said:
how? energy=mass * speed of light ^2
big woop. i don't get it.
mass is proportionately equal to energy but this doesn’t mean energy has mass.
elaborate please.
Yes, you are right. You don't get it. So try learning some relativity. That equation is NOT just a statement that two things are proportional. Wether an equation simply states a proportion or not depends on the physical meaning of the equation, not just the equation itself,
 
brandy said:
mass is proportionately equal to energy but this doesn’t mean energy has mass.
Hi brandy, maybe this can help. The general form of the equation is:
E^2 = m^2 c^4 + p^2 c^2
From this equation you can see that if energy is added and the momentum does not increase then the mass must increase. In that sense energy does have mass.
 
Of course energy has mass. In fact energy and mass are just 2 different words for one and the same thing.
e.g. gravity is the tendency of energy to attract other forms of energy. Therefore since matter is a form of energy it attracts other matter.
 
this also has the consequence that photons attract each other gravitationally
 
  • #10
brandy said:
Is the Mass Defect in the atom due to the Binding Energy and does this account for that small amount of mass?

I think of it as the binding energy is due to the mass defect.

binding energy = mass defect x c2
 
  • #11
If energy is mass, then why does gravity only accelerate a photon perpendicular to the direction of travel, never changing it's speed?
 
  • #12
Not sure what that has to do with the thread topic, but:

Since a photon is massless it must have speed c, therefore nothing will change that.

If the gravitational force is not acting perpendicular to the photon's direction, |p| will change for the photon, even though the speed does not change. I.e., its frequency will shift.
 
  • #13
HallsofIvy said:
Yes, of course. E= mc^2.

Agreed, though it might be easier for the OP to think of it this way:
Δm = ΔE / c2​
where ΔE is the binding energy, so this gives you the mass defect. And yes, it contributes to the total mass of the atom.
 

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