Einstein equations don't work at large scale?

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MTDismuke said:
You don't patch that; you replace it with fluid mechanics.
Please post the professional scientific source that describes this concept you are describing here.

MTDismuke said:
patches for a theory that tries to curve empty space
There is nothing wrong with empty spacetime having curvature. There is no a priori reason that it must be flat and considerable experimental evidence that it is curved.
 
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gen x said:
Where do you find this information? Why would they use relativistics physics for engineering like automobile, naval, structure industry, weather forecast, aerodynamics (navier stokes ), etc?

In technical university for engineering we didnt mention relativity even once, in 5 years of study...
Which speaks heaps to the applicability of Newton’s equations!
 
Hornbein said:
Newton thought that instantaneous action at a distance was absurd.
Could you provide the source where this is written?
(Newtonian mechanics is assumed that we have deal with instantaneous interactions. But Albert Einstein demonstrated that no interaction or transmission of information can occur faster than the speed of light.)
 
Mike_bb said:
Could you provide the source where this is written?
Here is a source:
Newton said:
That Gravity should be innate, inherent
and effential to Matter, fo that one Body
may act upon another at a Distance thro’
a Vacuum, without the Mediation of any
thing else, by and through which their
Action and Force may be conveyed from
E one
[ 26 ]
one to another, is to me so great an Ab-
surdity, that I believe no Man who has in
philosophical Matters a competent Faculty
of thinking, can ever fall into it. Gravity
must be caused by an Agent
Source (letter pages 25 and 26, PDF pages 29 and 30):
https://upload.wikimedia.org/wikipe...uments_in_proof_of_a_deity_(IA_b30368522).pdf
 
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MTDismuke said:
It’s a broken foundation, not a minor bug. Dark matter and dark energy are just math patches for a theory that tries to curve empty space instead of tracking actual physical pressure in a medium. You don't patch that; you replace it with fluid mechanics.
Can you cite credible technical references that promote this view and propose alternatives invoking "physical pressure in a medium"? "Broken" conventional cosmology of the universe is not set in "empty space" since it's filled with both a negative-pressure fluid (vacuum energy) as well as a (mostly) pressureless fluid (ordinary and cold-dark matter).
 
Dale said:
Relativity will always be valid where experiments have already confirmed it, just as Newton’s laws will always remain valid where experiments have already confirmed it.
I don't like hear that everything is or will be proved wrong.
This make me wonder, why I even learn about physics. I am so disappointed that physics is not 100% truth like math.
Why Tim say that Einstein relativity is also maybe wrong?

 
gen x said:
I don't like hear that everything is or will be proved wrong.
This make me wonder, why I even learn about physics. I am so disappointed that physics is not 100% truth like math.
Why don't you focus on mathematics then!
gen x said:
Why Tim say that Einstein relativity is also maybe wrong?


He is convinced that Bell's theorem and the experemental tests around it imly action at a distance incompatible with relativity. That's what happens when you believe strongly in an interetation.
 
gen x said:
I don't like hear that everything is or will be proved wrong.
The post from @Dale that you quoted does not say that. Indeed it says the exact opposite.

gen x said:
I am so disappointed that physics is not 100% truth like math.
Welcome to the real world, where things aren't 100% black and white. The only reason math is like that is that, where it's like that, it's disconnected from reality. As Bertrand Russell said, to the extent that the propositions of math refer to reality, they are not certain; and to the extent that they are certain, they do not refer to reality.

gen x said:
Why Tim say that Einstein relativity is also maybe wrong?
Because he's arguing about philosophy, not physics.

Go look at the experimental confirmation of relativity: for example, here:

https://link.springer.com/article/10.12942/lrr-2014-4

As @Dale said, relativity will always be valid where experiments have confirmed it. And indeed, as he said, the same is true of Newtonian physics. The fact that a theory has a limited domain of validity does not make it wrong.

But there are people, like Tim Maudlin, who don't like that, and who can only be satisfied with a theory that is guaranteed to be 100% right in an unlimited domain. No such theory has ever been discovered, and if past experience is any guide, none ever will, because we will never have experimental data covering an unlimited domain, and scientific theories have to be confirmed by experimental data. Physics is not math. Again, welcome to the real world.
 
gen x said:
This make me wonder, why I even learn about physics. I am so disappointed that physics is not 100% truth like math
You may want to study religion instead, if you are after 100% truth. If you want to study science then you will have to accept the inherent limitations of the scientific method.
 
PeterDonis said:
The post from @Dale that you quoted does not say that. Indeed it says the exact opposite.
Yes I know, I refer to my video

PeterDonis said:
As @Dale said, relativity will always be valid where experiments have confirmed it. And indeed, as he said, the same is true of Newtonian physics. The fact that a theory has a limited domain of validity does not make it wrong.
I think problem is not results that are not 100% correct but Newton consider time and space absolute, so foundations are wrong.
How do you look at this wrong concepts?
 
Dale said:
You may want to study religion instead, if you are after 100% truth. If you want to study science then you will have to accept the inherent limitations of the scientific method.
How do you explain that foundation of some theory are wrong, I mean that time , space, velocity are not absolute?
 
gen x said:
I know, I refer to my video
Then it's not clear to me why you quoted @Dale saying the exact opposite of what you said you were worried about.

gen x said:
Newton consider time and space absolute, so foundation are wrong.
How do you look at this wrong concepts?
That's philosophy, not physics. The physics is the math used to make predictions and the comparison of those predictions with experiment. You can't compare "concepts" with experiment. "Concepts" are human constructs; it's not clear that they even can be "right" or "wrong". When we use those terms informally to refer to concepts, we actually mean something more like "leads to conclusions we like" or "leads to conclusions we don't like". Which, again, is philosophy, not physics.
 
gen x said:
This make me wonder, why I even learn about physics. I am so disappointed that physics is not 100% truth like math.
You are certainly free to study math. In fact, studying math is often good for studying physics since physics uses a lot of mathematical concepts.

But in math and eventually even logic, you define what's true via your axioms. Whether those axioms are true in some platonic sense or simply true because we define the rules of the game that we play is also debated. In the philosophy of mathematics. And the philosophy of logic. So I can only wish you luck in finding what you really want to find. 🤣
 
PeterDonis said:
That's philosophy, not physics. The physics is the math used to make predictions and the comparison of those predictions with experiment. You can't compare "concepts" with experiment. "Concepts" are human constructs; it's not clear that they even can be "right" or "wrong". When we use those terms informally to refer to concepts, we actually mean something more like "leads to conclusions we like" or "leads to conclusions we don't like". Which, again, is philosophy, not physics.
I don't understand this part, you want to say that we can't know if time and space are relative or absolute?
 
Matterwave said:
But in math and eventually even logic, you define what's true via your axioms. Whether those axioms are true in some platonic sense or simply true because we define the rules of the game that we play is also debate
Can physics be set from axioms, from first principles that are "truth"?
 
gen x said:
I don't understand this part, you want to say that we can't know if time and space are relative or absolute?
Yes.

Our best current theory, relativity, includes the concept that those things are not absolute. But we don't know that that theory is fundamental. It could be emergent from something else at a deeper level in which time and space are absolute. (For example, I think @Demystifier has published a version of Bohmian mechanics in which relativity is emergent from a deeper model that works like this.) Or in which "time" and "space" don't even make sense as concepts at all, so asking whether they're "absolute" or not is just word salad. (At least one proposed theory for quantum gravity, loop quantum gravity, has this property.)

So the fact that relativity makes accurate predictions within the domain where it's been tested, and that relativity uses the concepts of time and space not being absolute, is no guarantee at all that those concepts are "right". But it does mean that, within the domain where relativity has been confirmed, those concepts are useful--because the theory that's been confirmed in that domain uses them.
 
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gen x said:
Can physics be set from axioms, from first principles that are "truth"?
Physical theories are mathematical systems, which means they are built from axioms that are assumed to be "true" in the context of the theory. You have to do that in order to make predictions.

But, as my previous post just now illustrates, the fact that such a theory makes accurate predictions within a certain domain does not mean the axioms on which it was built must be "true". All it means is that they are useful for making correct predictions within that domain.
 
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gen x said:
Can physics be set from axioms, from first principles that are "truth"?
There are things that are called "axioms" in mathematical physics. But they look quite different than the math ones. In QFT, you have the Wightman axioms. But go ahead and read the first axiom: https://en.wikipedia.org/wiki/Wightman_axioms and let me know if that feels like an "axiom" to you.

A simpler example of something similar are the postulates of special relativity, the postulate of relativity (equivalence of inertial frames) and the constancy of the speed of light in vacuum.

Any set of axioms or postulates, as they relate to a physical theory, must be tested and confirmed in a lab. Without the experiments to back them up, it's back to just being mathematics.

But consider. In modern foundations of mathematics, ZFC, the fact that the natural numbers exists as a set is due to two things, the axiom of infinity and a particular encoding, e.g. Von Neumann's or Zermelo's. The encoding is not unique and the axiom of infinity sure doesn't feel like it comes from pure logic.
 
gen x said:
How do you explain that foundation of some theory are wrong
It doesn’t matter. A theory doesn’t even need “foundations”.

What a theory needs is some mathematical framework that it can use to make predictions. But those equations and their predictions don’t need any foundations. And the foundations may still produce correct predictions in some experimental domain, even if those foundations are wrong in some other domain or in some philosophical sense.

As George Box said “All models are wrong, but some are useful”.
 
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Dale said:
It doesn’t matter. A theory doesn’t even need “foundations”.

What a theory needs is some mathematical framework that it can use to make predictions. But those equations and their predictions don’t need any foundations. And the foundations may still produce correct predictions in some experimental domain, even if those foundations are wrong in some other domain or in some philosophical sense.

As George Box said “All models are wrong, but some are useful”.
Ok physics is just mathematical system that must match experiment result, to the desired number of decimal places.
What theory mean for reality is irrelevant, left to each person's own interpretation.
 
gen x said:
to the desired number of decimal places
To the experiment’s number of decimal places.

gen x said:
What theory mean for reality is irrelevant, left to each person's own interpretation.
Yes, and (within the limits provided by experiments) each person is free to change their interpretation at any time for any reason.
 
Dale said:
Yes, and (within the limits provided by experiments) each person is free to change their interpretation at any time for any reason.
Does it mean that objective reality don't exist?
 
gen x said:
What theory mean for reality is irrelevant
So experimental results that match the theory's predictions don't count as "reality"? I think you're being too pessimistic here. When the GPS in your smartphone tells you accurately where you are, you're using the theory of General Relativity to tell you something very useful about reality.

gen x said:
Does it mean that objective reality don't exist?
Why would you think that? Aren't the things that, for example, the GPS in your smartphone tells you about where you are, things that are part of "objective reality"?
 
gen x said:
Does it mean that objective reality don't exist?
No. Experiments measure objective reality. That is why I put in the statement “within the limits provided by experiments”.

What it means is that a model (or its foundation) is not objective reality.
 
PeterDonis said:
Why would you think that?
Dale said:
What it means is that a model (or its foundation) is not objective reality.

Because some theories consider time as absolute, some as relative, some that don't exist etc etc...But in reality only one option can be true.
 
PeterDonis said:
What makes you think this?
Because this seems logic to me.
Why you think that is not case in reality?
 
gen x said:
Because this seems logic to me.
Why you think that is not case in reality?

It seems to me, you should translate "time is absolute" into a proper logical sentence and then you assume the law of excluded middle.

I shall wait for the translation. 🙂