Tom,

"A truly meaningless statement.'

If I make a comment, I'm a naive idiot. If I use someone else's comment, I'm 'cutting and pasting.'

Now the very words have no meaning!!!!!

Model:

noun;

11: a description or analogy used to help visualize something (as an atom) that cannot be directly observed

12: a system of postulates, data, and inferences presented as a mathematical description of an entity or state of affairs; also : a computer simulation based on such a system

verb;

1: to plan or form after a pattern : shape

3b : to produce a representation or simulation of

"It doesn't? "

As I recall, there is no reversed activity on the other side of absolute zero.

Regards,

John M

A model -- in the technical meaning that we should be using -- is a solution to an equation. You don't get to use it any way you please, and then pretend you are engaging in an objective rational discussion.

"As I recall, there is no reversed activity on the other side of absolute zero."

You recall that from ... where? And what do you mean 'absolute zero'? Not from anything I said.

Tom,

And weren't giant cosmic gear wheels the solution to the equations of epicycles? As multiverses, inflation, dark energy, super symmetry, etcetc, are the solutions to the various equations floating around now. Are the equations the final arbiter? Are the solutions inviolate?

Absolute zero is the thermal minimum, not just the center point on some graph. We are still trying to figure out how thermodynamics, the real physical processes, not just bare models, can go in reverse.

You keep waving these concepts and sources around as though they are some totem to prove your point, but when it finally gets down to unraveling all the mystery, they don't. So how long does this; "You don't understand zero!" go on for?

Regards,

John M

Eckard,

"The past extends endlessly to the left of the timescale and includes possible influences. The future extends to the right and includes expected effects.

By includes is to mean the past is merely the stage, but includes actors/actresses, which are substantial/extended objects. The past and future, not being part of the cast that play out the drama has no influence.

"You will hopefully agree that a singular moment has no extension and cannot have any effect".

I agree, just as the past and future cannot have any effect on the drama. With time (the stage) alone and no cast, there is nothing to watch. No Scene one, Act One, etc. The problem is that a cast without a stage, also leaves us with nothing to watch. But that is not to confuse things and say the stage is an actor influencing the drama, as Smolin seems to suggest by saying the past influences the future. You will agree that the stage does not influence what the future scene will be in a drama, neither does it influence what the past scene was. A stage is a stage and not part of the cast. Hope my analogy is apt?

Akinbo

"And weren't giant cosmic gear wheels the solution to the equations of epicycles?"

No.

"As multiverses, inflation, dark energy, super symmetry, etcetc, are the solutions to the various equations floating around now."

No. You are confusing model with theory.

"Are the equations the final arbiter?"

Of what?

"Are the solutions inviolate?"

If they are correct solutions, yes. Remember, though -- changing a parameter in the theory creates a different solution, a different model. It's the model that's tested against experimental physical phenomena; if what the model predicts happens, the model was a correct physical solution. A theory can be mathematically complete, though, and have nonphysical models unless, like Max Tegmark -- if I understand his view correctly -- one believes that all correct models of a mathematical theory have a physical correspondence. Could be.

"Absolute zero is the thermal minimum, not just the center point on some graph. We are still trying to figure out how thermodynamics, the real physical processes, not just bare models, can go in reverse."

I didn't say anything about temperature, John. You're missing something very important here.

Best,

Tom

Tom,

" It's the model that's tested against experimental physical phenomena; if what the model predicts happens, the model was a correct physical solution."

And if what the model predicts, isn't what is observed in experiments, do you review the model, or are you allowed to patch it with whatever best fits the gap between theory and observation?

"I didn't say anything about temperature, John. You're missing something very important here."

It is my impression that at absolute zero, thermodynamic processes come to a halt. Nothing about them going in the opposite direction. What I'm not missing is that we are discussing whether, like time in spacetime models is symmetric and processes can be reversed in simple thermodynamic models, but not in actual thermodynamic processes, does that suggest that maybe spacetime is a basic model of relating actions and events and not some underlaying physical cause of them. So that the reason time is asymmetric in the course of actual events is because it is a part of the puzzle not covered by the spacetime model.

Regards,

John M

"And if what the model predicts, isn't what is observed in experiments,"

Then the model is falsified, but not necessarily the theory.

" ... do you review the model, or are you allowed to patch it with whatever best fits the gap between theory and observation?"

Are you allowed to use mortar to hold bricks together? Or is a pile of bricks just okay for you?

"'I didn't say anything about temperature, John. You're missing something very important here.'"

It is my impression that at absolute zero, thermodynamic processes come to a halt."

Since it is impossible in principle to reach absolute zero, you obviously have the wrong impression.

Tom,

"Are you allowed to use mortar to hold bricks together? Or is a pile of bricks just okay for you?"

If your theoretical model ends up being 95 percent mortar and 5 percent brick, you might want to try another model.

" Which is why all action is stationary (zero) and reversible. Which makes your speculation from here onward unphysical."

"Since it is impossible in principle to reach absolute zero, you obviously have the wrong impression."

Do I sense a disconnect here, between actions being described as "stationary (zero)" and actually reaching that state? How do you get everything going in reverse, if you can't stop it in the first place?

Regards,

John M

A question for Einsteiniana and the 'crackpots' wanting to bring down the house:

Space-time around Earth is said to be curved by earth's gravity.

When Earth moves does it carry this curved space-time along with it or does it newly curve space-time in its new position, while the formerly curved space-time left behind becomes uncurved?

Akinbo

    "If your theoretical model ends up being 95 percent mortar and 5 percent brick, you might want to try another model."

    No theoretical model predicts that result. The problem is that we *observe* 95 percent mortar (dark matter, dark energy) and 5 percent brick (baryonic matter). What you erroneously think are "patches" to theory are only ways to try and find the parameters that make the predictive model correspond to the observation. Until you grasp this, you are not doing physics.

    "Do I sense a disconnect here, between actions being described as 'stationary (zero)' and actually reaching that state? How do you get everything going in reverse, if you can't stop it in the first place?"

    I continue to resist explaining the principle of least action to you. You're on your own. If you ever do get it, I expect it will be an epihany. Good luck.

    Best,

    Tom

    Tom,

    Obviously they didn't predict it!! Or there would be no reason for the patch! So we have a universe that is 95 percent invisible to anything other than as patches to an expanding universe theory and that doesn't include what percentage of overall energy inflation would be. On the other hand, if we considered a model where redshift is an optical effect of light crossing enormous distances, there would be no need for either inflation or dark energy, since they are only to physically expand the space. Nor would the galaxies have to form and evolve in only a few billion years. Heck, it takes our galaxy a 1/4 of a billion years to make just one rotation. So the issue of how they evolve and what holds them together would be quite different. For one thing, if galaxies are dynamic entities, with no particular age, then since the first generation stars tend to be on the perimeters, they would be seeding the inner, second generation stars, in a more continuous funneling process, not the current inside out model, where the galaxies are simply growing larger and the outside is just more recent.

    The argument is there is no optical effect that would cause redshift, but look at it from the other direction and just assume, for modeling purposes, that there were; What would we see? Light redshifted entirely proportional to distance, with no lateral effects, since we may not be at the center of the universe, but we are at the center of our optical view of it. Which is just what we do see.

    So now lets put the two theories on a scale and see how much 'mortar' is takes to make each work; On one side we have to accept inflation, dark energy and some extremely fast galactic and galaxy cluster evolution, that only comes close to making sense by pushing the parameters of what we know about cosmic development way over into the red zone of what is theoretically possible. Not to mention my little point about how relativity makes a poor excuse for expansion, when there is no increasing propagation rate to keep the light speed constant to this expanded space.

    Now, on the other side of the scale, all we need is to find a way for light to be redshifted over extreme cosmic distances, such as this.

    "If you ever do get it, I expect it will be an epihany."

    All I'm seeing are some fairly basic modeling assumptions. An epiphany is when all the parts suddenly fit together as one, not when you have to use a bunch of mortar.

    Regards,

    John M

    Akinbo,

    What would space be, if it had no physical features to bend, limit, or move it? It would have two characteristics; One, lacking bounds, it would be infinite. Two; lacking motion, it would be inert.

    Now what are the main characteristics of the matter and energy occupying space? Energy expands out, to infinity, or the closest it has potential. Matter balances energy into increasingly inert formations. So these two features of space set the parameters of what occupies it. Now neither reaches these goals, but ultimately what stops them is the cycle back in the other direction. Energy eventually becomes so diffuse, it becomes just background radiation, likely eventually coalescing into elemental forms of intergalactic gases, while mass is continually breaking down in its effort to become ever more dense and stable, thus radiating back out and what does fall into the center of galaxies, appears to be ejected across the cosmos as jets of cosmic rays, seeding other processes.

    Time and temperature are just measures of change and microscopic kinetic energy.

    Regards,

    John M

    John M,

    Yes, perhaps "we are at the center of our optical view of [the universe]". May I suspect that the radius of that sphere (IIRC about 15 000 000 000 lys) deserves a scrutiny? As a naive layman I wonder if it doesn't matter whether or not the measurement includes a relativistic correction of the Doppler effect. Recently I heard that mature structures of were found even as remote as 11 000 000 000 lys.

    This was a surprise to the experts.

    Eckard

    John,

    RE: What would space be, if it had no physical features to bend, limit, or move it? It would have two characteristics; One, lacking bounds, it would be infinite. Two; lacking motion, it would be inert.

    What of the converse? That is, what would space be if it had physical features to bend, limit, or move it? I suspect the converse is true and I tried to support this in my essay contribution.

    By the way, your puzzles on F = ma and what mass fundamentally is are not yet fully grasped. But I agree it may not be fundamental like length and time.

    Akinbo