A Meaningful Questions about Photons and Matter.

[Markus Hanke]

4 hours ago, J.Merrill said:

Well waves are disturbances traveling through a medium, so if the medium does not exist and the Propagation of the waves do, then what is it that allows this?

The medium does exist - it is the electromagnetic field (in classical physics). This field extends through all of space and time, and EM waves are excitations of this.

Going further, into quantum field theory, there are quantum fields that correspond to the elementary particle types - there’s an electron field, a photon field etc etc. At the moment this is our most fundamental description of reality - which is not to say that there mightn’t be something even more fundamental. There almost certainly is.

This may be of interest - if you delineate a volume of space, and then ask “how many particles are in this volume?”, it turns out that the answer depends on the observer! Where one observer sees an empty vacuum, another observer might see a thermal bath of many particles - within the same volume, and all other conditions remaining equal. So the question as to existence and nature of particles isn’t as straightforward as one might think - thinking of them as ‘little balls of matter’ is quite meaningless.

Edited June 21, 2022 by Markus Hanke

[swansont]

9 hours ago, J.Merrill said:

We cant Directly observe photons, they are theoretical constructs that reveal to us matter they interact with.

Yes. There’s a lot of things like that in physics. Physics doesn’t describe reality; it describes how nature behaves.

So photons may not be real, but nature behaves as if they are.

[NTuft]

On 6/20/2022 at 10:07 AM, J.Merrill said:

Indeed, if you think about photons as packets with size increasing with wavelength, you'd expect lower frequency photons to "occupy" more space. In reality, it's the opposite - so lower frequencies allow you to fit more photons in the same volume.

On 6/20/2022 at 3:43 PM, sethoflagos said:

On 6/20/2022 at 2:19 PM, J.Merrill said:

there is no physical size to a HIGH C note.

Good!

Well, if you graph the frequency HIGH C is distinguishable from C. If we could see vibrations it would have size I'd say. Phonons are thought of as quantized sound, kind of like a condensed matter physics equivalent of photons.
It seems to follow that we can see part of the EM spectrum, we can infer that something is being transmitted to our visual receptors, and I think we explain that through the idea of photons carried by the EM wave through the EM field.
 

 

On 6/20/2022 at 10:07 AM, J.Merrill said:

Do photons take up space?

The answer is YES.

Are you sure? Here's another thread:

 

[Markus Hanke]

20 hours ago, swansont said:

So photons may not be real, but nature behaves as if they are.

I love this +1

[sethoflagos]

6 hours ago, NTuft said:

Well, if you graph the frequency HIGH C is distinguishable from C. If we could see vibrations it would have size I'd say. Phonons are thought of as quantized sound, kind of like a condensed matter physics equivalent of photons.
It seems to follow that we can see part of the EM spectrum, we can infer that something is being transmitted to our visual receptors, and I think we explain that through the idea of photons carried by the EM wave through the EM field.

I think you know very well that the air inside the Albert Hall is not condensed matter. Therefore it doesn't support normal modes of oscillation. Therefore it doesn't transmit phonons. 

When I visualise High C, I visualise some emergent residue of say 10^30+ air molecule collisions. A residual vector of the time averaged exchange of momentum having some detectable periodicity in the vicinity of 1046.5 Hz.

Trying to ascribe a spatial size to a momentum vector, or an emergent property such as sound seem to me as ludicrous as assigning a spatial size to temperature, the colour green, or perceived beauty.

Or photons come to that.  

Edited June 22, 2022 by sethoflagos

[studiot]

1 hour ago, sethoflagos said:

I think you know very well that the air inside the Albert Hall is not condensed matter. Therefore it doesn't support normal modes of oscillation. Therefore it doesn't transmit phonons. 

When I visualise High C, I visualise some emergent residue of say 10^30+ air molecule collisions. A residual vector of the time averaged exchange of momentum having some detectable periodicity in the vicinity of 1046.5 Hz.

Trying to ascribe a spatial size to a momentum vector, or an emergent property such as sound seem to me as ludicrous as assigning a spatial size to temperature, the colour green, or perceived beauty.

Or photons come to that.  

Indeed so. +1

I would just add to that :-

The volume occupied by any wave has a time value attached since all waves expand from thier point of origin over time.
So you can't just say the sound occupies 20 litres but you have to say "it occupies 169 litres after 1 second" or similar depending on when you measure it.

 

[sethoflagos]

4 minutes ago, studiot said:

Indeed so. +1

I would just add to that :-

The volume occupied by any wave has a time value attached since all waves expand from thier point of origin over time.
So you can't just say the sound occupies 20 litres but you have to say "it occupies 169 litres after 1 second" or similar depending on when you measure it.

 

Thanks!

Two neon atoms in an otherwise empty small box. They collide. Where is the sound?

[studiot]

38 minutes ago, sethoflagos said:

Thanks!

Two neon atoms in an otherwise empty small box. They collide. Where is the sound?

Two neon atoms in an otherwise empty bar ??

Surely the sound is the question who is paying for the drinks ?

🙂