Can Energy Exist Without Mass?

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Discussion Overview

The discussion centers around the relationship between energy and mass, specifically whether energy can exist independently of mass. Participants explore theoretical implications, examples from physics, and the nature of photons in relation to mass.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants propose that energy can exist without mass, citing photons as evidence.
  • Others argue that energy only has meaning in relation to mass, suggesting that energy without matter would be undetectable.
  • A participant discusses the concept of binding energy in atoms, questioning how energy can exist without physical bodies.
  • There is a mention of the universe's initial state being pure energy, with mass emerging later.
  • Some participants discuss the implications of heat death and the potential existence of a sea of photons at the universe's end.
  • There is debate about the interchangeability of mass and energy, with some asserting they are not the same despite being related.
  • Participants explore the concept of mass in relation to photons, discussing rest mass versus relativistic mass.
  • One participant expresses confusion about the nature of mass and its understanding in physics.

Areas of Agreement / Disagreement

Participants express a range of views on whether energy can exist without mass, with no consensus reached. Some agree that photons represent energy without mass, while others maintain that energy cannot exist independently of mass.

Contextual Notes

Discussions include unresolved questions about the nature of mass and energy, the definitions of mass in different contexts, and the implications of physical theories on these concepts.

Who May Find This Useful

Readers interested in theoretical physics, the nature of energy and mass, and the implications of relativity may find this discussion relevant.

  • #31
Drakkith said:
Why is wikipedia saying that photons have mass then? Not rest mass, no. But look at my quote. Are they just wrong or is this some kinda gray area or misunderstood area?

Here's the http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/tdil.html" :

m = \gamma m_0

where m_0 is the rest mass, and \gamma is the usual relativistic factor.

What is m when the rest mass is ZERO? What do you believe more? Wikipedia, or the physics? What is the credential of the person (or persons) who wrote that Wikipedia entry that you trust so much?

Light has MOMENTUM. The apparent "inertial" reaction that light has is due to this momentum, not due to "mass", relativistic or not. There is no "gray or misunderstood area" here.

Zz.
 
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  • #32
Drakkith said:
Why is wikipedia saying that photons have mass then? Not rest mass, no. But look at my quote. Are they just wrong or is this some kinda gray area or misunderstood area?
Your quote does NOT say that photons have mass. You misread/overinterpreted a simplistic bullet point. For full treatment you should read the full article they linked at the end of the point!

...or better yet, read the article specific to the question: the photon article. It says in plain english a dozen times that the photon has no mass!
 
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  • #33
russ_watters said:
Your quote does NOT say that photons have mass. You misread/overinterpreted a simplistic bullet point. For full treatment you should read the full article they linked at the end of the point!

...or better yet, read the article specific to the question: the photon article. It says in plain english a dozen times that the photon has no mass!

Photons have mass because they have momentum and if they had no momentum they wouldn't exist because photons can't exist without momentum so they must have mass
 
  • #34
Jarfi said:
Photons have mass because they have momentum and if they had no momentum they wouldn't exist because photons can't exist without momentum so they must have mass

This is wrong. You need to read the PF FAQ in the General Physics forum first before making such statements.

Zz.
 
  • #35
Jarfi said:
Photons have mass because they have momentum and if they had no momentum they wouldn't exist because photons can't exist without momentum so they must have mass

Only according to classical Physics P(Momentum)=Mass*Velocity! Not according to modern Physics where all u need is energy to carry it!:)
 
  • #36
russ_watters said:
Your quote does NOT say that photons have mass. You misread/overinterpreted a simplistic bullet point. For full treatment you should read the full article they linked at the end of the point!

...or better yet, read the article specific to the question: the photon article. It says in plain english a dozen times that the photon has no mass!

What article at the end of the point? (Did I misunderstand what a "Point" is in wikipedia? I didn't see anything linked after the part I quoted.)

Alright, I wholeheartily agree that photons have no mass. I've read up a little bit more on it all and it appears to me that there is simply a lot of confusion over the concept of mass. This quote from Einstein sums it up pretty well in my opinion.

It is not good to introduce the concept of the mass of a moving body for which no clear definition can be given. It is better to introduce no other mass concept than the 'rest mass' m. Instead of introducing M it is better to mention the expression for the momentum and energy of a body in motion.

Gotta go do some stuff here at work, I'll be back later.
 
  • #37
In addition to my previous post, I have read that the concept of Relativistic mass is outdated and not used anymore. No wonder there's confusion...

So, Photons have NO mass of any type (since I guess there's really only 1 type of mass, rest mass?).
 

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