Dimensions

[MigL]

People who are unconfortable with the notion of time always claim that time depends on the 'motion of something', because we can only measure it that way.
They fail to realize that motion depends on time, and, without time you cannot define motion of anything ( including vibrations ).
 

We have classical Galilean mechanics, which is highly effective where applicable, but sometimes its use becomes quite cumbersome.
As Swansont pointed out with his 'ball thrown up in the air' example, we can use Lagrangian mechanics in a conservative gravitational field, to simplify our calculations, without taking things to the most fundamental level of x,y,z, and t.
Lagrangian and Hamiltonian mechanics help simplify matters, but in applications where relativistic effects become dominant, energy treatments ( because energy is frame dependent ) also become untractable ( maybe not for Markus, but certainly for me ).

There are many concepts, other than energy,we also use to 'simplify' our calculations; velocity, momentum, phase, etc. but fundamentally, they all depend on the configuration of x, y, z, and t.

Edited August 1, 2022 by MigL

[exchemist]

1 hour ago, mistermack said:

That's why my OP was a question, an invitation to debate. 

 

A photon is decribed as a "packet of energy".  And it moves at the speed of light in a vacuum. Surely that means moving energy? The ball is composed of energy, if E=MC²    , so you are tossing a lump of energy in the air.      

A photon is not, or should not be,  described as a packet of energy. Energy is not stuff. It's just a property of a system, like momentum. A photon is not "made of" energy, it "has" energy - along with a number of other properties. A photon is sometimes described as a wave packet, https://en.wikipedia.org/wiki/Wave_packet , but not an energy packet. 

Systems that move (relative to others) and have energy will naturally carry that energy with them, so yes, that energy moves, but only as a result of belonging to the system that moves.  To describe a photon as moving energy is not correct.  

Similarly a ball is a physical object - a system. It has mass as one property, and that mass is associated with a rest energy by E=mc². But the ball is not "composed of" mass, so it is not "composed of" energy either. It has both mass and energy, along with radius, colour, maybe spin, smell.......etc. All these are just properties of the ball. It is the ball that you toss in the air, not any one of these properties.    

[joigus]

Very interesting topic with very interesting contributions.

You can always make a bundle of variables with space, time, and momentum, or energy or anything you wish. The relevant question is, as Swansont and Exchemist and others pointed out/implied, whether there is any geometrically meaningful information to attach to it (orthogonality, distance, parallelism, scale independence, etc.)

Mathematically, the key point is invariance group of your physical laws. Groups of transformations are other words for class of transformations that relate valid observers or coordinatisations that make your physical laws invariant.

But first, you cannot forget relativity. So if you wish to attach any geometric meaning to energy, you must not forget it goes along with momentum, (E,p) so as to make a 4-vector in Minkowski space.

Bundling together space-time variables with energy-momentum variables is trickier, but you can do it. If you re-write mechanics in the light of Lagrange and Hamilton's formalism, you can see there are valid groups of transformations relating, eg, x (position) and p (momentum). These are called canonical transformations, but their intuitive/operational meaning is far less clear. This (x,p) geometry is very far from intuitive and is called symplectic.

Primitive concepts aren't particularly useful until you formulate far-reaching general relations between them.

[mistermack]

39 minutes ago, exchemist said:

A photon is not, or should not be,  described as a packet of energy. Energy is not stuff.

Well, ok, things might have moved on. But that's how Einstein described it. " In 1905, Albert Einstein published a paper in which he proposed that many light-related phenomena—including black-body radiation and the photoelectric effect—would be better explained by modelling electromagnetic waves as consisting of spatially localized, discrete wave-packets.^[10] He called such a wave-packet the light quantum (German: das Lichtquant).       https://en.wikipedia.org/wiki/Photon        

So is a wave "stuff" ? In any case, I thought that the e in  E=MC²   was the energy of a particle, and hence the energy of stuff.                    

[MigL]

2 minutes ago, mistermack said:

So is a wave "stuff" ? In any case, I thought that the e in  E=MC²   was the energy of a particle, and hence the energy of stuff.     

None of that is inconsistent with energy being a property of 'stuff'.
A wave has ( the property of ) energy, yet can also be handled mathematically by a 'phonon'.

Phonon - Wikipedia

You use whichever model best suits the situation.

[swansont]

1 hour ago, mistermack said:

I didn't say planetary orbit. This is the usual attempt at nit-picking. 

Wikpedia said "Thus, the planetary model of the atom was discarded in favor of one that described atomic orbital zones around the nucleus where a given electron is most likely to be observed ".^[31][32]

^{https://en.wikipedia.org/wiki/Atom#Energy_levels}  

Nit-picking is actually required sometimes. The terminology we use often has specific meaning, which is why "orbital" is used rather than "orbit" because they refer to different things. We can't read your mind to know what you mean, we have to go by what you actually say/write. 

Orbit, as you wrote, implies motion. QM orbitals do not imply motion within an atom.

[mistermack]

23 minutes ago, swansont said:

Nit-picking is actually required sometimes. The terminology we use often has specific meaning, which is why "orbital" is used rather than "orbit"

But you made the unwarranted snarky leap that I was "People who don't know what they are talking about" because I wrote orbit. In this case it was wrong, because I did know that electrons don't orbit in a planetary fashion. So it didn't naturally follow. If you want only physicists to post in speculations, maybe you should make that clear. I already made it clear earlier in this thread that I'm not one. Hence imprecise terminology. I'm interested, that's all.

My OP was not pushing "my theory", I haven't got one. It was just to see what others thought, and there have been some interesting informative posts, yours included. 

[exchemist]

1 hour ago, mistermack said:

Well, ok, things might have moved on. But that's how Einstein described it. " In 1905, Albert Einstein published a paper in which he proposed that many light-related phenomena—including black-body radiation and the photoelectric effect—would be better explained by modelling electromagnetic waves as consisting of spatially localized, discrete wave-packets.^[10] He called such a wave-packet the light quantum (German: das Lichtquant).       https://en.wikipedia.org/wiki/Photon        

So is a wave "stuff" ? In any case, I thought that the e in  E=MC²   was the energy of a particle, and hence the energy of stuff.                    

But be careful. Notice Einstein spoke of wave-packets, not energy packets, in line with what I said previously. The light quantum refers to the observation that the energy in light is only transferrable in discrete portions, which he called quanta. That does not mean light is "made of" energy. 

E=mc² is the simplified version of a longer formula: E² = (mc²)² + p²c², in which p is the momentum of the entity in question. For an entity at rest relative to the observer, p=0 so it reduces to the familiar formula. However for a photon, this does not apply. On the contrary, for a photon, m=0, so the expression reduces to E=pc.

(If you apply de Broglie' relation to that, by which p=h/λ, and use the fact that c=νλ,  you get E=hν, Planck's well-known formula for the energy of a photon.)

I agree "stuff" is not a precise term. What I was trying to say, in colloquial language, is that energy can't exist on its own, any more than momentum can, or electric charge. None of these is something you can isolate. You can't have a jug of momentum or a bottle of electric charge. They can only exist as properties of some physical system, by which I mean one or more material entities (whether QM or classical) or fields.

A wave is a system that in general comprises a medium (which is physical, i.e "stuff"), physically disturbed from its equilibrium state, with the result that the disturbance propagates through the medium. To disturb it from its equilibrium state requires an energy input, so yes, a wave has energy in it. An EM wave is a bit of a special case in that the "medium" consists of electric and magnetic fields which oscillate. But fields are physical too: you can get a spark from the stored energy in an electric or magnetic field under the right conditions e.g. the pop you hear when the older type of electric train suddenly cuts off the current in mid-acceleration, due to the collapse of the magnetic field in the windings. The energy is a property of the field, not something in its own right.  

In summary both entities with mass and waves "have" energy, as a property, but this does not mean either of them "is" energy.   

[swansont]

53 minutes ago, mistermack said:

But you made the unwarranted snarky leap that I was "People who don't know what they are talking about" because I wrote orbit. In this case it was wrong, because I did know that electrons don't orbit in a planetary fashion. So it didn't naturally follow.

You said orbit, and said it implied movement. There is no denying that. And by using the terminology and description, you give the impression that you don't actually know the correct model. You suggest that I made an unwarranted conclusion, but I say I made one based on the evidence before me.

If it's the case that you misspoke, then all you have to do is say that, and we can move on to the next point about how we had gone from energy to movement; the original claim was about the latter, not the former.

 

53 minutes ago, mistermack said:

If you want only physicists to post in speculations, maybe you should make that clear. I already made it clear earlier in this thread that I'm not one. Hence imprecise terminology. I'm interested, that's all.

That's not what I said, so I will you refer you to your own comment about snarky responses. What I want is for people to be able to back up what they claim, and to have put in the minimal effort of learning the basics, rather than going on some wild conjecture.

 

53 minutes ago, mistermack said:

My OP was not pushing "my theory", I haven't got one. It was just to see what others thought, and there have been some interesting informative posts, yours included. 

I will repeat: the claim was not in the OP, and was not phrased as a question. I was presented as a fact. You followed up with "As far as my imagination takes me, if no energy moved in the universe, there would be no time expended."

Which is fine as a concept to explore, but you have to be prepared to defend it, or you can accept responses from people who are correcting misconceptions. You've been fighting that. 

[mistermack]

15 minutes ago, exchemist said:

But be careful. Notice Einstein spoke of wave-packets, not energy packets, in line with what I said previously. The light quantum refers to the observation that the energy in light is only transferrable in discrete portions, which he called quanta. That does not mean light is "made of" energy. 

Thanks, good post. (to me) But say you have a stretched rope, and you send a "wave-packet" along it with a single twitch, isn't that energy that you put into it the wave packet, and the rope just the medium? And likewise, the photon is the energy, and the field the medium? 

 

27 minutes ago, exchemist said:

In summary both entities with mass and waves "have" energy, as a property, but this does not mean either of them "is" energy.

But if you compare a field with no photon, and a field with a photon passing through it, then the difference between the two is the photon, and isn't that difference the passing of an energetic phenomenon? So the photon is the energetic occurrence, and the field is the enabling condition?

59 minutes ago, swansont said:

You said orbit, and said it implied movement. There is no denying that.

Does "orbital zone" not imply movement then? And I'm not arguing, I am interested in the facts. I pictured an indistinct cloud, of a moving electron, that couldn't be pinned down, from what I have read. I thought that movement was inherent in that picture, even if it can't be predicted or tracked. 

[swansont]

32 minutes ago, mistermack said:

Does "orbital zone" not imply movement then?

Where (i.e. in what context) does this term show up? AFAIK it's not phrasing that's used much in QM.

 

Quote

I pictured an indistinct cloud, of a moving electron, that couldn't be pinned down, from what I have read. I thought that movement was inherent in that picture, even if it can't be predicted or tracked. 

An electron is a wave. The "cloud" in this description is a probability of finding it somewhere if you were to try and localize it; the probability function looks like a cloud. But one has to not try and impose notions of classical physics on this description - it would be incorrect to think of the electron existing at specific points at times when you aren't measuring it, and that it's moving from place to place. Because it is a wave, it exists everywhere.

[exchemist]

14 minutes ago, mistermack said:

Thanks, good post. (to me) But say you have a stretched rope, and you send a "wave-packet" along it with a single twitch, isn't that energy that you put into it the wave packet, and the rope just the medium? And likewise, the photon is the energy, and the field the medium? 

 

But if you compare a field with no photon, and a field with a photon passing through it, then the difference between the two is the photon, and isn't that difference the passing of an energetic phenomenon? So the photon is the energetic occurrence, and the field is the enabling condition?

If you jerk a rope, you displace a portion of it upward from its lowest energy state, which means you put gravitational potential energy into a section of the medium (the rope). The portion of the medium that is displaced upward then travels, but the energy is still at all times in the medium, just not always in the same part of it. In the case of the photon, the energy is in the travelling disturbance in the electric and magnetic fields.

You can certainly say the photon is the energetic occurrence, but the energy is still in the fields. Think what happens when a photon is absorbed by an electron in an atom. The changing electric field of the photon creates a forced oscillation in the electron (using classical language, more properly a "transition dipole moment") that moves it to a higher energy orbital. So it's the oscillating field that gives up energy to the electron. It's essentially the same as happens in the antenna of a radio receiver, but on a smaller scale.

 

[swansont]

I would add that the photon does not require any external field. No photon, E and B have zero amplitude. There is no analogue of the rope present.