Nature of Energy

[Alex K]

If it makes sense to say time is infinitely divisible doesn't that imply that it isn't linear?  

How would one (nonlinear) follow from the other (infinitely divisible)? I don't see that.

[little_monkey]

Wow, so much nonsense in this thread, I wouldn't know where to start...

Do you disapprove of something I said?

Before we get into any discussion we need to establish some parameters only to avoid what happened in a previous thread where insults were thrown, and hopefully since then, we've reconciled. However, to remind you, I was a professor for years, today I'm retired, but the professor is still in me. I'm used to walk into a class, where I'm the authority, and my students listen. I've also been to many seminars in which I sat quietly and listened because the person in front of me had greater authority than me in the matters presented. So I know when it's time for me to be  the professor and when I should be the student. Right now, I've read your posts in this thread, and I can only come to the conclusion that you are a confused student. You might know a lot, and perhaps more than me, but in the understand department, there is definitely a lot of room to improve. I hope you don't take this last remark as an insult. If that's okay with you so far, we can proceed.

[Alex K]

Do you disapprove of something I said?

Before we get into any discussion we need to establish some parameters only to avoid what happened in a previous thread where insults were thrown, and hopefully since then, we've reconciled. However, to remind you, I was a professor for years, today I'm retired, but the professor is still in me. I'm used to walk into a class, where I'm the authority, and my students listen. I've also been to many seminars in which I sat quietly and listened because the person in front of me had greater authority than me in the matters presented. So I know when it's time for me to be  the professor and when I should be the student. Right now, I've read your posts in this thread, and I can only come to the conclusion that you are a confused student. You might know a lot, and perhaps more than me, but in the understand department, there is definitely a lot of room to improve. I hope you don't take this last remark as an insult. If that's okay with you so far, we can proceed.

Of course I take it as an insult

But go on, point to something I said you think is wrong, and tell me why.

[I_am_not_mafia]

I want a good clean fight. No gouging. Stop when your opponent taps out and no strikes to the groin.

[little_monkey]

Before we get into any discussion we need to establish some parameters only to avoid what happened in a previous thread where insults were thrown, and hopefully since then, we've reconciled. However, to remind you, I was a professor for years, today I'm retired, but the professor is still in me. I'm used to walk into a class, where I'm the authority, and my students listen. I've also been to many seminars in which I sat quietly and listened because the person in front of me had greater authority than me in the matters presented. So I know when it's time for me to be  the professor and when I should be the student. Right now, I've read your posts in this thread, and I can only come to the conclusion that you are a confused student. You might know a lot, and perhaps more than me, but in the understand department, there is definitely a lot of room to improve. I hope you don't take this last remark as an insult. If that's okay with you so far, we can proceed.

Of course I take it as an insult

But go on, point to something I said you think is wrong, and tell me why.

I said confused, so get that right...  

I'm not going to go point by point, what you have in your post is too convoluted. But as a starting point: Energy being the most powerful concept?? No, I can tell you that the field concept is by far more powerful - it gives you Maxwell's equation ( E-M united with light), Einstein's GR, and QFT.  Without the field concept, you and I are reduced to point mechanics. Do you have any idea how far you can get with point mechanics?? Not very far...

I'm not saying that energy isn't important, it is important, but in the scheme of thing, yes in the  top 10. What is the most important for you to understand? I'm not playing 10 questions for you to guess it right. I will tell you because I know you don't know the answer. Thinking I'm kidding. Try kinematics. 

Yep, if you don't understand kinematics, you can never never never formulate a proper dynamical theory. Do I have your attention now?

Thanks Galileo for making us aware of that. Case in point: it was Einstein that changed the laws of kinematics and told us: now go back to square one and upgrade your dynamics. He pointed out that the Galilean transformations were no longer adequate to take into consideration of the constancy of the speed of light. So all the books had to be rewritten for this new kinematics. You see, you didn't learn kinematics in high school before dynamics because, well, kinematics is easier than dynamics. No, you've learned it first because if you don't get your kinematics right then forget about even thinking of dealing with dynamics. 

I have to stop here. Will continue some other time...

[Alex K]

@little_monkey

You misunderstood. I didn't mean that energy is the most important concept in physics in general. Read again what I wrote, the sentence is: "Other conserved quantities,...but.....", so I was saying that among the conserved quantities encountered in systems, energy tends to be the most important one [because it is encountered in most systems, and because it is often closely related to the hamiltonian which describes the dynamics of the system ].

Do you have some more substantive and justified criticism we can discuss?

[I_am_not_mafia]

Energy being the most powerful concept?? No, I can tell you that the field concept is by far more powerful

I have no qualifications in physics but I do understand how useful concepts can be and how they come in and out of fashion in science.

Maybe it's irrelevant to this conversation, I don't know, but in my own field of Artificial Intelligence, everything is understood in terms of information. While this is a useful concept, I personally find the concept of free-energy (i.e. energy that can do work) more useful. Very few people think in these terms. But that's because I research entirely self organising systems whereas most people try to create systems that can be trained.

And before the fashion of applying information theory to life, neuroscientists were trying to understand the brain as if it was a computer. They understood intelligence as a logical process. I remember reading the most painful paper once where the authors described emotions as functioning like interrupts in a computer. It wasn't so long ago that it was common to think of symbols actually existing in the brain.

Maybe this is not the same as to what you're referring to, but this doesn't necessarily mean that one concept is wrong and the other is correct, merely that one is more useful in a certain context than the other.

[little_monkey]

@little_monkey

You misunderstood. I didn't mean that energy is the most important concept in physics in general. Read again what I wrote, the sentence is: "Other conserved quantities,...but.....", so I was saying that among the conserved quantities encountered in systems, energy tends to be the most powerful one because it is encountered in most systems, and because it is often closely related to the hamiltonian which describes  the dynamics of the system.

Me, misunderstanding?? No way, 

Your Hamiltonian is important because we need it to do perturbation theory. It doesn't play much of a role in non-perturbative theories ( for instance, String Theory). The Lagrangian is far more important - it's with the Lagrangian you get your symmetries checked out, and most importantly, your Lorentz invariance is absolutely crucial  to go from QM to QFT, and you get your theory Lorentz invariant through the Lagrangian. Moreover, the people in the 50's and 60' couldn't figure out the nuclear forces, both the weak and the strong. You don't know the force you're pretty much handicapped in developing any dynamical theory. So the whole plan was: try guessing the Lagrangian - you know if you have it right, you also know you have the right equation of motion. It was a nice way to circumvent not knowing the nuclear forces, and with Yukawa's idea, we could ignore "force" and replace it with "interaction".

[little_monkey]

Energy being the most powerful concept?? No, I can tell you that the field concept is by far more powerful

Maybe this is not the same as to what you're referring to, but this doesn't necessarily mean that one concept is wrong and the other is correct, merely that one is more useful in a certain context than the other.

Clarification: I wasn't saying that energy is wrong in my post to Alex, but my comment pertained in how important it is. It is important but not as important as he would like to think. As to the rest of your post, I'm not qualified to shed any light.

[Chas]

Do you disapprove of something I said?

Before we get into any discussion we need to establish some parameters only to avoid what happened in a previous thread where insults were thrown, and hopefully since then, we've reconciled. However, to remind you, I was a professor for years, today I'm retired, but the professor is still in me. I'm used to walk into a class, where I'm the authority, and my students listen. I've also been to many seminars in which I sat quietly and listened because the person in front of me had greater authority than me in the matters presented. So I know when it's time for me to be  the professor and when I should be the student. Right now, I've read your posts in this thread, and I can only come to the conclusion that you are a confused student. You might know a lot, and perhaps more than me, but in the understand department, there is definitely a lot of room to improve. I hope you don't take this last remark as an insult. If that's okay with you so far, we can proceed.

This is neither a classroom nor a seminar, it is a discussion.  I can only come to the conclusion that you are a confused retired professor.