You cannot support any of the examples you have brought up with galaxies! The so-called "evidence" is circular! Stick with something much more managable... what is the rest-mass of our sun and how was this determined?
Aer: Suppose I take 2 protons and two neutrons, give them some kinetic energy, and slam them into each other hard enough for them to fuse to form a Helium nucleus. It is observed that the rest mass of the Helium nucleus is less than the combined rest masses of the constituent particles. Question: If all this is carried out in a sealed box, do you think the gravitational influence of the box's contents will be greater before or after the fusion reaction? Why?
This has nothing to do with kinetic energy. This has everything to do with binding energy on the quantum level. You know very well that your example of slamming particles together will not result in the formation of a helium nucleus, such things happen within the intense pressure of stars. I do not claim to know what everything about quantum physics which such an example would require us to analyze.
You told me to review my past posts for no good reason, so I told you to make a similar review for no good reason. Fair? I think so Please Register or Log in to view the hidden image!
Sorry I missed this Pete, I got caught up in conversation with a monkey Please Register or Log in to view the hidden image! Anyway, explain away Please Register or Log in to view the hidden image!
Physics Monkey, I don't want to be insensitive here.. but I see our converstation going nowhere soon. I've been through this before, we'll be on page 12 of this thread and you'll claim kinetic energy contributes to gravity and I'll claim that your argument is circular and unacceptable and we'll continue on to page 20 Please Register or Log in to view the hidden image! Let's allow Pete to provide his approach.
Aer, based on your ideal gas comment and your dismissal of cosmological data, I feel that your argument misunderstands the role and necessity of approximation in physical theories. I obviously don't have the time or proper references at the moment to personally try to convince you that the whole edifice of astronomy and astrophysics is not based on flights of fancy. I also think, based on your discussions of "the gravitation of a body", that your argument does not take the fullness of GR into account. No hard feelings, I agree we aren't getting anywhere, and I'm happy to give Pete a chance Please Register or Log in to view the hidden image! .
Aer: So, although you don't know how to solve the problem, you know kinetic energy isn't involved. How interesting. Your changing your claim is a good reason. Fair? I think so.
I know the explanation to the problem, binding energies are negative potentials on the quantum level. The why what and how... I do not know, I am not aware that anyone "knows" Please Register or Log in to view the hidden image! notwithstanding unproven theories abound. I've never changed my claim, I have however provided contradictory analysis from physicists if that is what you are referring to.
Yes, I very much do misunderstand the role and necessity of approximations in exact theories. Are you saying General Relativity is not suppose to be an exact theory to explain phenomena in the universe? Perhaps you are talking about so called "theoretical results" in engineering, in which approximations are taken to get a close "theory" prediction. Theory is suppose to give you an exact answer if all your assumptions are exactly true. However these assumptions are never exactly true so reality always deviates from theory. Theory inherently does not include approximations to arrive at an exact solution from exact assumptions.
Aer: You went from: to: You changed your claim. Your physicists support the second claim, which nobody disputes, but not the first. See?
No James R, I do not see! You are correct that physicists accept the second and not the first, but that is not a change of claim on my part! I am claiming, kinetic energy does not contribute to gravity in both of those quotes your provided. That is the same claim I've made all along. The fact that someone may agree with one of my claims and not the other does not make my claims change! Please Register or Log in to view the hidden image! I swear James R, you can be really dense sometimes.
Aer, approximations are almost always used both in the initial conditions and the subsequent predictions when we use a physical theory to explain experimental data. There are of course some known exact solutions to any theory, and these solutions are very useful for building understanding. However, in most cases the answer we get out from our initial conditions, even if they were perfect, is itself only approximate simply because we can't mathematically solve the theory.
Well, this thread rolled into a ditch and then hit a telephone pole. So let's start over with a clean slate. It is accepted by everyone I believe that rest mass contributes to gravity. Now, when we start talking about the rest mass for a compound object, I think we are going to slam into sharp disagreements. This was the perspective that I think Pete was starting to come from but where o where is Pete?
