Does Wave Motion Challenge the Energy-Matter Relationship?

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Discussion Overview

The discussion revolves around the relationship between wave motion and the energy-matter relationship, particularly in the context of energy transfer without matter transfer. Participants explore definitions of wave motion and its implications for established physics concepts, including E=mc².

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • One participant questions the definition of wave motion as energy transfer without matter transfer, suggesting it contradicts established principles of energy and mass.
  • Another participant explains that mechanical waves transfer energy through a medium without the medium itself moving, using sound and water waves as examples.
  • A participant expresses confusion about energy transfer in waves, mentioning the absence of a medium for electromagnetic waves and raising concerns about relativistic effects.
  • Examples are provided, such as microphones and electric guitars, to illustrate how energy can be transferred without the movement of matter.
  • One participant identifies E=mc² as the equation in question, positing that energy transfer implies mass transfer.
  • Another participant asserts that mass is indeed transferred, referencing nuclear reactions as an example.
  • A later reply challenges the necessity of mass transfer by citing the example of laser beams, which transfer energy without transferring mass.

Areas of Agreement / Disagreement

Participants express differing views on whether energy transfer necessitates mass transfer, with some arguing that it does and others asserting that it does not. The discussion remains unresolved regarding the implications of wave motion on the energy-matter relationship.

Contextual Notes

Participants reference various examples and concepts, but there are unresolved assumptions regarding the definitions of waves and the conditions under which energy and mass transfer occur.

3trQN
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Wave motion is a means of energy transferrence without there being any transfer of matter...

Thats a quote from one of my physics texts, but it seems to me to contradict what I've been tought about enrergy and matter thus far, which isn't much i must add.

If wave motion can be defined as energy transfer without matter transfer, then doesn't that violate the famous equation?

If so, how would you define a wave?
 
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I think what they are trying to say is this: A mechanical wave transfers energy through a medium, but the medium itself does not get transferred from one point to another. Like sound energy travels through the air, but the air itself doesn't travel. (It just vibrates back and forth.) Or a ripple of a water wave traveling outward without the water itself moving outward.

(Don't worry about relativistic effects, if that's what you are thinking.)
 
How is energy transferred in a wave?

I understand the role of a medium for a mechanical wave, and that there is an absence of a medium for an electromagnetic wave moving through free space, or more to the point, the medium is ( though not a true medium ) the oscillations in the elctronic and magnetic fields.

I apreciate your reply, but i am worrying about relativistic effects :) maybe you can help clear my confusion a little.

Another thing that bothers me, is, hypothetically speaking, assuming the parallel postulate to be flase, what effect would such a condition have on the EM wave model?

thx :)
 
3trQN said:
If wave motion can be defined as energy transfer without matter transfer, then doesn't that violate the famous equation?
What equation?

Consider a microphone: sound waves cause it to vibrate, generating electricity, yet the air isn't moving from one place to another.

Consider an electric guitar - the guitar string doesn't move away from the guitar, yet it generates electricity in the pickup.

Consider an old-style reciprocating steam engine: the piston moves back and forth (net displacement: zero), yet it produces energy by spinning a shaft.
 
E=mc^2 was the equation i was referring to.

If you transfer energy, then don't you also transfer some mass?
 
Yes, actually, you do. It's the reason the components of a nuclear bomb have less mass after the bomb goes off than before it goes off.
 
really?

i don't think you need to transfer mass. for example, fire a laser beam. you transfer energy but no mass (considering photons to be massless).
 

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