Are Photons Tangible Entities or Merely Energy Manifestations?

[Moonrat]

Yes, there is always internal motion, but there's no apparent motion that can account for the difference between particles in different positions in a gravitational field. Also, there is the problem of direction that I mentioned.



No, you're not mistaken, it's just that what you have presented is not enough to justify the identification "motion is energy".

My friend, help me here then because I cannot find one distinction where there is 'motion' and no 'energy'

Motion may be 'non-directional' so therefore, it does not create direction but rather the direction is created by mass, and in relation to other mass..

motion by itself may be unpredictable, as such when we enter the quantum realm, which is, if I am not mistaked, pure energy quantified.

motion by the way I see it is motion, big or small, and all things at their essence being composed of matter and motion, mass and energy, order and choas.

perhaps as we break things down into the quantum realm the distinctions become more blurred, but where can we have energy without motion? Motion, movement, vibration...zzzzzzzzzzzzzzzz.! Even my DNA 'vibrates'.

Velocity is only then relative to the relationship to the speed of light and mass, then, a vector or map of the motion, not the motion in and of itself?

Thank you again, you must being getting tired with all of this?

 

[zoobyshoe]

Ach, no, that's not what I meant. I was using the word "equivocation" in the specialzed sense of logic...
...Sorry for the misunderstanding.

Thanks for clearing that up.

 

[Math Is Hard]

Thank you again, you must being getting tired with all of this?

I also thank you, Tom. It is a great service what you do here.

 

[zoobyshoe]

My friend, help me here then because I cannot find one distinction where there is 'motion' and no 'energy'

See if this helps:

When we consider motion we are considering the phenomenon of change of location. Change of location is our focus and concern when we consider motion. The word "motion" was invented (or arrived at) to describe the phenomenon of change of location.

When we consider energy, we are considering the ability to do work, or, more broadly, to effect change. When we look at a thing in physics with respect to its ability to effect change, or work, then we are looking at it in terms of its energy. We aren't, in this case, focusing on the phenomenon of change in location, even if that is also happening.

The difference is one of our perspective: each word desgnates a different human concern about the matter, and they refer to two separate concerns. They really can't be used interchangably.

While it is true that all things that are in motion have energy, the terms "motion" and "energy" are referring to quite separate aspects of the situation. You can say "Where there's motion, there's energy" but not "Motion is energy". As Tom pointed out you can also say "Where there's momentum, there's energy." But not "Momentum is energy", because momentum means something different than energy, just as motion means something different than energy. Being found together does not make them the same thing.

Hope that helps, and hope I haven't misstated anything.

 

[Moonrat]

See if this helps:

When we consider motion we are considering the phenomenon of change of location. Change of location is our focus and concern when we consider motion. The word "motion" was invented (or arrived at) to describe the phenomenon of change of location.

hmm, so it is more semantical, based on my subjective understanding of the word 'motion'..I see, my understanding of motion does not = the objective usage of the word motion, so I can now see that, as a formulae, motion does not = energy..

BUT! energy can be understood easier by understanding motion, since the two seem to be flip sides of the coin...they are distinguishable aspects of the same thing, quantified and separated for mathematical simplicity...

I don't define motion as 'velocity' I define motion, to myself, as non-directional energy, work, or movement...

as an example, and this may explain my perspective, I study a few of the chinese arts, you know, tai chi and that sort of thing..I noticed in the chinese movements, there is internal 'energy' which is also 'internal motion'. THe energy in the movements is not directed by the energy or the motion, but by the mind (yi in chinese) moving the 'center' or center mass. the 'energy' is just the wave or motion that is directed.

I was startled to discover these princaples of physics inside of this ancient chinese art, who developed these uncanny movements over thousands of yeas, anyway, it gives one a good laboratory to study the motion and mass of things, the human body..

so human beings have our internal motion or energy, feelings and the like..I like to keep things 'human' for myself and other laypeople, but still keep the objectivity of the science intact..

thanks all, I sure do appreciate this forum! Yikes, who needs college with you guys!

Moonrat

 

[zoobyshoe]

hmm, so it is more semantical, based on my subjective understanding of the word 'motion'..I see, my understanding of motion does not = the objective usage of the word motion, so I can now see that, as a formulae, motion does not = energy.

I think you are starting to understand the problem. It is actually not that your understanding of "motion" is different than the "objective" usage. It is different than the physics usage.

In order to be able to speak of things and understand each other, physisists have had to deliberately define many, many terms in very specific ways. A "particle" in physics isn't the same as the everyday use nor does it just refer to elementary particles like electrons, protons, neutrons, and photons. In the right sitution, the Earth itself can be called a "particle" in physics.

Alot of terms have both an everyday use and meaning, and a different, much more specific, physics definition. This can trip people up if they're not aware of the specific physics terminology.

 

[quantumdude]

My friend, help me here then because I cannot find one distinction where there is 'motion' and no 'energy'

There is the example I already cited: Gravitational potential energy. What is moving there? Also, rest mass energy does not seem to be connected to any motion.

Motion may be 'non-directional' so therefore, it does not create direction but rather the direction is created by mass, and in relation to other mass..

Don't understand this part.

motion by itself may be unpredictable, as such when we enter the quantum realm, which is, if I am not mistaked, pure energy quantified.

What is "pure energy quantified"?

motion by the way I see it is motion, big or small, and all things at their essence being composed of matter and motion, mass and energy, order and choas.

OK, but that still doesn't establish the identity "energy is motion". Have you not understood my reasons for saying that?

perhaps as we break things down into the quantum realm the distinctions become more blurred, but where can we have energy without motion? Motion, movement, vibration...zzzzzzzzzzzzzzzz.! Even my DNA 'vibrates'.

Right, but I have already cited examples of energy that are not connected to motion. The fact that everything moves is not sufficient to establish that "energy is motion".

Velocity is only then relative to the relationship to the speed of light and mass, then, a vector or map of the motion, not the motion in and of itself?

I'm confused.

*Velocity has no relation to mass.
*A vector is not the same thing as a map, but you seem to be treating them as though they are.

 

[zoobyshoe]

There is the example I already cited: Gravitational potential energy. What is moving there? Also, rest mass energy does not seem to be connected to any motion.

Excuse me for stepping in on this point. If you cite "potential" energy then you must ask where is the "potential" motion. Where the "potential" motion is in the case of Gravitational potential energy and rest mass energy is therefore clear. The coexistence of the concepts of energy and motion remains intact.

 

[quantumdude]

If you cite "potential" energy then you must ask where is the "potential" motion.

The point is that the particle in the gravitational field has nonzero energy, even when it is not moving. Sure, motion and energy can "coexist". Indeed, they must! But this is a clear cut case in which an energy form is not associated with motion.

Yes, there is the potential for motion, but the fact is that there is no motion until the energy changes form to kinetic energy (which is explicitly the energy of motion).

 

[zoobyshoe]

The point is that the particle in the gravitational field has nonzero energy, even when it is not moving.

This concept of non-zero energy may be over my head. I haven't run into this term before. You may need to explain.

This is the way I understand it, correctly or incorrectly: if we speak of a particle at rest on top of a skyscraper on the verge of being blown off the edge by the wind so it can fall to the ground, then we can calculate its gravitational potential energy. This is a potential only. It doesn't actually acquire this energy till it falls. We can use it to do no work whatever, nor will it effect any changes, until it falls. As long as it is at rest, it has no real energy. There is the potential for energy by virtue of its height and the acceleration of gravity which will kick in as soon as the skyscraper is no longer blocking its path.

Yes, there is the potential for motion, but the fact is that there is no motion until the energy changes form to kinetic energy (which is explicitly the energy of motion).

My reasoning is that there is also no energy until kinetic energy kicks in. Prior to that it remains only a potential.

Now, when you speak of "non-zero" energy, you may be into a concept that is different than potential energy that is above my head at this point.

 

[quantumdude]

This is the way I understand it, correctly or incorrectly: if we speak of a particle at rest on top of a skyscraper on the verge of being blown off the edge by the wind so it can fall to the ground, then we can calculate its gravitational potential energy. This is a potential only. It doesn't actually acquire this energy till it falls. We can use it to do no work whatever, nor will it effect any changes, until it falls. As long as it is at rest, it has no real energy.

No, that's not right. It really does have the energy. If it didn't, then we couldn't say that energy is conserved.

The gravitational potential energy before the drop is equal to the kinetic energy just before it hits the ground.

There is the potential for energy by virtue of its height and the acceleration of gravity which will kick in as soon as the skyscraper is no longer blocking its path.

Potential energy is not "the potential for energy". It is an energy form in its own right.

 

[chroot]

This concept of non-zero energy may be over my head. I haven't run into this term before. You may need to explain.

He's simply saying that if you hold a brick in the air, it has potential energy. If you drop it on your toe, you'll discover how much. It doesn't matter if you're holding the brick still or not.

- Warren

 

[Math Is Hard]

I have a some what related question, and I hope it's not too far off topic. We were talking about freefall in class and my teacher said that before freefall begins (from whatever height) at time=0 an object's acceleration is = 9.8 m/sec^2, even though velocity =0 and distance = 0.
If I were to graph the acceleration of freefall of an object on Earth as a function of time, at t =0 I would be tempted to draw an open circle at the beginning of a horizontal line of y = 9.8, and thereby specify that acceleration > 0 only at the the fraction of a second that the object begins to move. What is the flaw in my reasoning? Thank you.

 

[krab]

If I were to graph the acceleration of freefall of an object on Earth as a function of time, at t =0 I would be tempted to draw an open circle at the beginning of a horizontal line of y = 9.8, and thereby specify that acceleration > 0 only at the the fraction of a second that the object begins to move. What is the flaw in my reasoning? Thank you.

...and so you say if you were to throw a stone up in the air, it would have a constant acceleration of 9.8m/s^2 everywhere in its trajectory, except at its highest point where v=0? Why? Doesn't make any sense to me. Just because v=0 does not mean the rate of change of v is zero. Or think of a pendulum: at the extreme point of the swing, v=0 but a= a maximum; right when it passes through centre, v= a maximum, but a=0.

 

[zoobyshoe]

He's simply saying that if you hold a brick in the air, it has potential energy. If you drop it on your toe, you'll discover how much. It doesn't matter if you're holding the brick still or not.

OK. Just checking to make sure "non-zero energy" wasn't a specialized term.

 

[quantumdude]

OK. Just checking to make sure "non-zero energy" wasn't a specialized term.

Nope, I just meant that the value of the energy is something other than zero. Of course, one could argue that the zero of energy could be set at any point, which is of course true. But, if you put two identical particles at two different heights, both motionless, then they will certainly have different potential energies (they can't both be zero!), then we have an example of two particles with the same motion (that is, *no* motion, relative to the Earth) and two different energies.

 

[Molydood]

I have a question which may help (certainly for me) to clear up any confusion regarding potential energy and it's relation to conservation of energy. Consider the following example:

Two planets in space, both have an attraction to one another, and are slowly moving together. They have a certain quantifiable potential energy (correct?) If we were to suddenly move one of the planets as quickly as physically possible, to another part of the universe, would that potential energy then be removed also? Or just shifted so that other objects now closer by would be in receipt of this energy?

I say to move the planet quickly as I have a feeling that if it was done slowly the potential energy would be converted to kinetic by 'tugging' the other planet with it, but it's really an unsubstantiated assumption on my part that the speed of movement in this case is related to the amount of effect it has on the other object.

thanks,
Martin

 

[Math Is Hard]

...and so you say if you were to throw a stone up in the air, it would have a constant acceleration of 9.8m/s^2 everywhere in its trajectory, except at its highest point where v=0? Why? Doesn't make any sense to me. Just because v=0 does not mean the rate of change of v is zero. Or think of a pendulum: at the extreme point of the swing, v=0 but a= a maximum; right when it passes through centre, v= a maximum, but a=0.

Thank you, dear Krab. Excellent example. That helped a lot!