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Is Gravity a Force?


Davy_Jones

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33 minutes ago, TheVat said:

So,  have to ask,  is string theory physics?  Or,  because we don't know to what degree it might describe the real world,  is it a theoretical framework that lies on the borderlands of metaphysics? 

String theory seems to describe a landscape of possible universes,  most of which intelligent life can never behold.   At least, with Davy's long-fingered lemurs,  we can go to Madagascar and look at quite a few of them.  (careful,  they will steal your glasses)

String theory [misappropriatly named] is a QGT that remains hypothetical because we are totally unable to observe or experiment at such quantum/planck levels. It is though said to be a "beautiful picture" of what could/might be.

The same sort of speculation is talked about by Lawrence Krauss in his book, "A universe from nothing" I personally differentiate it from any run-of-the-mill speculation by referring to it as educated speculation...same of course applies to string theory and its derivitives.

22 hours ago, Davy_Jones said:

Would it be accurate to say that contemporary physicists continue to speak of gravity as if it were a force, even though (assuming Einstein got it right) it is not . . . perhaps out of deference to their scientific forebears, or to engender a sense of continuity?

Anyway, the question in short: Is gravity a force or not? (In layperson's terms, insofar as possible)

Interested to hear any comments. Thanks!
 

I think you are trying to see problems where there is no problem. Other then of course we do not really know what gravity is, and I don't believe we ever will until you can tell me, [as I mentioned previously] why does mass/energy make spacetime curve? 

Again, we have two extraordinary correct models of gravity that work well, each within their zones of applicability. There are also other models that do not work as well as GR....MOND, Vector 4 Gravity and probably others.

At this time I might raise one of my favourite short videos by a well respected Physicist that I believe applies here ....

But hey! I'm not a physicist, so perhaps you have a point. I just fail to see it at this time.

Edited by beecee
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39 minutes ago, beecee said:

I think you are trying to see problems where there is no problem. Other then of course we do not really know what gravity is, and I don't believe we ever will until you can tell me, [as I mentioned previously] why does mass/energy make spacetime curve? 

 

Going back to Jones and his lemur fixation, let us suppose for the sake of argument that no one knows why aye-ayes are nocturnal while many other lemurs are diurnal. Does it follow from this that Jones does not know what an aye-aye is?

I don't think so. We'd just say Jones knows what an aye-aye is alright; he just doesn't know why they are nocturnal.

 

Let us now suppose no one knows why mass/energy makes spacetime curve. Does it follow from this that no one knows what gravity is?

I don't think so.

 

Two points to note:

1. It may be the case that no one knows what gravity is. It does not seem to me, however, that this follows from the fact (if it is) that no one knows why mass/energy makes spacetime curve.

2. It seems to me there is no shortage of people claiming to know what gravity is. Anyone, say, who believes the general theory of relativity to be literally true (i.e. a more-or-less faithful representation of reality, as opposed to a mere model or calculating instrument) is effectively claiming to know what gravity is. ("It is the curvature of spacetime . . . etc., etc.")

Whether they do know or not is another matter, of course.

Edited by Davy_Jones
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1 hour ago, Davy_Jones said:

Let us now suppose no one knows why mass/energy makes spacetime curve. Does it follow from this that no one knows what gravity is?

I don't think so.

No supposing, we don't know why mass/energy makes spacetime curve, except that it is part of the model we call GR. We see the effects of gravity when spacetime is curved/warped/twisted. Yes we can then answer that gravity is geometry, but why?

What is spacetime? It is simply the framework within GR, where we  locate events and describe the relationships between them in terms of spatial coordinates and time. The concept of spacetime follows from the observation that the speed of light is invariant, or it does not vary with the motion of the emitter or the observer. Spacetime allows a description of reality that is common for all observers in the universe, regardless of their relative motion. In GR, gravity is described in terms of curvature of spacetime. GR has made incredible predictions, that are now validated...BH's, gravitational waves. But it still has its limitations and cannot therefor be taken literally. It fails us at the quantum/planck level in the first instant after the BB, and also fails us at the heart of BH's. The $64,000,000 question is will a validated QGT tell us what gravity is? Are gravitons [the theoretical particle that transmits gravity] real? If so, then there is the answer! I think.

1 hour ago, Davy_Jones said:

 It seems to me there is no shortage of people claiming to know what gravity is. Anyone, say, who believes the general theory of relativity to be literally true (i.e. a more-or-less faithful representation of reality, as opposed to a mere model or calculating instrument) is effectively claiming to know what gravity is. ("It is the curvature of spacetime . . . etc., etc.")

Whether they do know or not is another matter, of course.

Scientists imo anyway, mostly simplify things for public consumption...not sure if that is entirely a good thing. They talk of gravity being a force, but forget to metion, only in the Newtonian concept. They talk about it as curved spacetime or geometry, when briefly explaining GR and relativity in general. Did you watch the video? only 7.5 minutes long, and sort of explains what I'm having difficulty with.

In essence the facts are while we [scientists] are accurately able to describe and predict gravity, we still do not understand the deeper meaning of what it actually is. What is space? What was there before space and time evolved at the BB, are similar metaphysical questions at this time, although some scientists have made educational guesses and speculated on what such things are.

 

Edited by beecee
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If all you had to go by was a picture of an aye-aye, or a model of one, would you know what it is, or its properties are ?
Physicists deal with models of reality; does space-time actually curve, or does the co-ordinate system we assign to space-time only curve ? Is there actually such a thing as space-time ?
Our models only describe certain facets of reality, and are incomplete, or only applicable in certain circumstances; the only model that FULLY describes reality, is reality itself.

That is the 'reality' of the situation, not an ideology or a philosophy.

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3 hours ago, Davy_Jones said:

Edit P.S. Other fairly standard realist responses would look something like the following:

"If a theory is empirically adequate (i.e. saves the phenomena), moreover, yields new and surprising predictions then we have good reason to believe that it is true"

 Just a slight addendum. The above should read:

[Many scientific realists would say] "If a theory is empirically adequate (i.e. saves the phenomena), moreover, yields new and surprising predictions --which are subsequently corroborated--then we have good reason to believe that it is true"

And "true" here means literally true.

 

More later. Thanks again to all contributors.

 

 

13 minutes ago, MigL said:

If all you had to go by was a picture of an aye-aye, or a model of one, would you know what it is, or its properties are ?
Physicists deal with models of reality; does space-time actually curve, or does the co-ordinate system we assign to space-time only curve ? Is there actually such a thing as space-time ?
Our models only describe certain facets of reality, and are incomplete, or only applicable in certain circumstances; the only model that FULLY describes reality, is reality itself.

That is the 'reality' of the situation, not an ideology or a philosophy.

[my emphasis in red]

 

Apparently Einstein himself thought so, at least in his later years.

 

Quote

In particular, following his conversion [from antirealism to realism], Einstein wanted to claim genuine reality for the central theoretical entities of his general theory, the four-dimensional space-time manifold, and associated tensor fields. This is a serious business for if we grant his claim, then not only do space and time cease to be real, but so do virtually all of the usual dynamical qualities.

- Arthur Fine, "The Shaky Game", p123
 

Edited by Davy_Jones
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Einstein also thought there was a unified field theory that would unite Electromagnetism, gravity and the strong force, in his later years.
Before we uncovered the color interaction , of which a side effect is the strong force, or even the weak interaction.
Nobody's perfect; Newton had a lot of 'faulty' thinking also.

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I thought it might be fruitful to quote philosopher of science Arthur Fine at some greater length. Assuming our contributors here constitute a representative sample of scientists as a whole, Fine would appear to be right on the mark. i.e., GR, properly understood, is merely a model, a calculating device, not a representation of reality.

 

(from the same source, same page)


 

Quote

 

In particular, following his conversion [from antirealism to realism], Einstein wanted to claim genuine reality for the central theoretical entities of his general theory, the four-dimensional space-time manifold, and associated tensor fields. This is a serious business for if we grant his claim, then not only do space and time cease to be real, but so do virtually all of the usual dynamical qualities. Thus motion, as we understand it, itself ceases to be real.


The current generation of philosophers of space and time (led by Howard Stein and John Earman) have followed Einstein's lead here. But, interestingly, not only do these ideas boggle the mind of the average man in the street (like you and me), they boggle most contemporary scientific minds as well. That is, I believe the majority opinion among working, knowledgeable scientists is that general relativity provides a magnificent organizing tool for treating certain gravitational problems in astrophysics and cosmology. But few, I believe, give credance to to the kind of realist existence and nonexistence claims that I have been mentioning. 


For relativistic physics, then, it appears that a nonrealist attitude was important in its development, that the founder nevertheless espoused a realist attitude to the finished product, but that most who actually use it think of the theory as a powerful instrument, rather than as expressing a "big truth."

 

 

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2 hours ago, Davy_Jones said:

I thought it might be fruitful to quote philosopher of science Arthur Fine at some greater length. Assuming our contributors here constitute a representative sample of scientists as a whole, Fine would appear to be right on the mark. i.e., GR, properly understood, is merely a model, a calculating device, not a representation of reality.

Most scientific theories are models that match what we observe, aligns with the results of our experiments, and makes validated predictions. The longer in time that they continue to be sucessful, the more certain they become and probably closer to this reality you speak of. At the pinnacle of scientific theories is the theory evolution, an incontrovertible fact that organisms  change, over time. 

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1 hour ago, beecee said:

Most scientific theories are models that match what we observe, aligns with the results of our experiments, and makes validated predictions. The longer in time that they continue to be sucessful, the more certain they become and probably closer to this reality you speak of.

I am going to take you up on this because, as ever, things are more complicated than this over exaggerated popsci ideal.

Yes theories must match any observations in their domain of applicability but,

There are situations (theories) where we have learned to make a transformation of a difficult problem to an easier one, solve the easier one and make a reverse transformation back to the original.
These techniques (theories) can be be very successful and as accurate as required.
It is often stated in popsci that relativity is the most tested theory or QM is the most tested theory.
Again this is an exaggeration. The theories I am referring to have never been know to fail, yet they premise upon which they are founded is known to be imaginary.

I refer to such techniques as Virtual Work, Maxwells Mesh Method, the theory of logarithms, and many more.

 

8 hours ago, Davy_Jones said:

Sir/madam, I've been slightly overwhelmed here, struggling to understand most of it. Grateful nonetheless for so many informed responses.

 

If you're referring to your question "What is a force?" that's an easy one. My answer: "I dunno".

 

Thank you for your response

I did not ask you to answer this question

You asked specifically

On 9/1/2021 at 3:26 AM, Davy_Jones said:

Anyway, the question in short: Is gravity a force or not? (In layperson's terms, insofar as possible)

and I responded specifically to this request with a request for clarification to avoid discussion at cross purposes, which most of this thread has been.

19 hours ago, studiot said:

Before offering any discussion I would be interested to learn what you understand by a 'Force' ?

I ask this because your question is clear cut black and white yet most things in Nature become more complicated than that when we enquire more deeply into them, often much more complicated.

Forces and how they operate, what other physical quantities they affect or need and so on fall into the category of being much more complicated.

Even when considered in a newtonian manner, gravity operates differently from say electromagnetism, although there are similarieties as well.

Note I did not ask you to define a force or state what a force is.

But I did offer reasons for my quandrary because you had already pointed out that different scientists, in different situations, use the term force in different ways.

This is a fair and reasonable observation that deserves proper discussion.

So I just wanted to get us on the same page as to the sort of force we were talking about.

I was also trying to acceed to your request about using layman's terms, since laymen are even more hazy about forces than scientists.

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To put it in layman's terms this is my understanding:

Newton (Newtonian gravity) - gravity is a force that causes objects of mass to attract each other.

Einstein (General relativity) - gravity is not a force but the curvature of space time caused by the presence of mass (also energy but lets keep it simple in this context) where objects follow this curvature resulting the appearance of attraction.

Quantum Mechanics (Quantum gravity) - gravity is a force/field where gravitons are exchanged between masses resulting in interaction causing mutual attraction. 

The Newtonian model works very well for general predictions and suitable for most applications. The GR gravity model has been confirmed to produce more accurate predictions than the Newtonian gravity model, therefore supersedes as the best model of gravity we have. The GR gravity model predicts absurd results when used at the quantum level, predicting things like singularities... The quantum gravity models (hypothesis) solve this issue, however do not (as yet) consolidate with GR which has been verified as the best model of gravity we have. 

Maybe we are looking at this from the wrong perspective? Maybe focussing on "what gravity is" is not the answer to solving this dilemma. I think learning the nature of "what space-time is" will reveal what gravity is. 

Please jump in and correct my understanding! this subject is one that is most intriguing to me, and one I want to learn much more about.   

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@ Studiot

What is my understanding of a "force", you ask.

What immediately comes to mind are the words of St. Augustine (musing over time rather than force):

Quote

What then is time? If no one asks me, I know what it is. If I wish to explain it to him who asks, I do not know.

 

That said, my own understanding of force--assuming I had anything intelligent to say on the subject at all--doesn't seem particularly relevant here. The reason I started this thread was in the hope of gaining some expert (= you guys) clarification into what strikes my layman's lugs as a pair of mutually inconsistent claims that I frequently hear, namely:

1. Gravity is one of the fundamental forces of nature
and
2. Gravity, under general relativity (which I take, perhaps mistakenly, to be current orthodoxy), is not a force at all.

(See OP for more)

 

14 minutes ago, Intoscience said:

Please jump in and correct my understanding! this subject is one that is most intriguing to me, and one I want to learn much more about.   

I second that emotion!

Edited by Davy_Jones
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52 minutes ago, Davy_Jones said:

@ Studiot

What is my understanding of a "force", you ask.

What immediately comes to mind are the words of St. Augustine (musing over time rather than force):

 

That said, my own understanding of force--assuming I had anything intelligent to say on the subject at all--doesn't seem particularly relevant here. The reason I started this thread was in the hope of gaining some expert (= you guys) clarification into what strikes my layman's lugs as a pair of mutually inconsistent claims that I frequently hear, namely:

1. Gravity is one of the fundamental forces of nature
and
2. Gravity, under general relativity (which I take, perhaps mistakenly, to be current orthodoxy), is not a force at all.

(See OP for more)

 

I second that emotion!

 

Can I just tell you something before I reply ?

The use of the @ symbol on this site, in front of the member name,  works to provide a notification to that member of a reply.
But you have to do it correctly.
Type the @symbol.
Then start typing the member name. (case is important here)
The site will offer a drop down box with suggested members that is adjusted as you type more letters.
Select the appropriate member.

The result will look like this

@Davy_Jones

But if you use the quote function from their post the member will also be notified.

Hope this helps

Now to your question.

Thank you for the reply.

That's cool and I have a better idea of where you are coming from. You also seem to be more au fairt with Philosophy authors or scientists discussing the philosophy of science.

As such have you heard of Berkson ?

He has written a philosophical book on this subject

Berkson  : Fields of Force  : Routledge.

 

My own answer is that that 'It depends upon the circumstances'.

Consider a standard red post box such as you will find all over the UK.
This one is situated under a street lamp with a sodium bulb.


What colour is it ?

Answer, it depends upon circumstances.

In the day it is red, in the night it is black.

For your question about gravity, there are many more circumstance.
It depends upon scale and distance amongst other things.
For instance if you wished to consider the structural mechanics of a dam, Newtonian force analysis is 100% accurate, whilst GR will not help you one bit.
So in those circumstances gravity is a distributed force.
In the circumstances controlling the motion of the planet Mercury, Newtonian force analysis is less than 100% accurate, whilst the GR view is nearly so, to the limits of our measurement capability.

 

Does this move the discussion forward ?

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Some of you may be familiar with the wonderful lecture series produced by "The Teaching Company" (aka "The Great Courses", I think).

Right now, by chance, I'm going through their course entitled "The Evidence for Modern Physics: How We Know What We Know" presented by professor Don Lincoln.

Quote

 

Don Lincoln is a Senior Scientist at Fermi National Accelerator Laboratory (Fermilab). He is also a Guest Professor of High Energy Physics at the University of Notre Dame. He received his Ph.D. in Experimental Particle Physics from Rice University.

Dr. Lincoln’s research has been divided between Fermilab’s Tevatron Collider, until its close in 2011, and the CERN Large Hadron Collider, located outside Geneva, Switzerland. The author of more than 1,000 scientific publications, his most noteworthy accomplishments include serving on the teams that discovered the top quark in 1995 and confirmed the Higgs boson in 2012. He is a fellow of the American Physical Society and the American Association for the Advancement of Science.

 

https://www.thegreatcourses.com/professors/don-lincoln

 

Near the end of Lecture 15, "The Awesome Evidence for General Relativity", at the 28:30 mark, Prof. Lincoln perorates:

"I hope I've convinced you that there are very good reasons that general relativity has been very clearly validated. I mean I know that it's very weird to think of gravity as the bending of space and time, but it's just literally impossible to believe otherwise these days."


So, pace other contributors to the thread--perfectly entitled to their opinions--who have told us that no one knows what gravity is, or science cannot answer questions such as what gravity is, clearly, Prof. Lincoln does not share your skepticism.

The good professor is not only telling us what gravity is (It's the bending of space and time), but that to believe that gravity is anything other than the bending of space and time is not possible.

A tad hyperbolic if you ask me, but hey, I toss it out here for consideration. :) 

 

 

Edit P.S. Also for everyone's reference, Prof. Lincoln opens the same lecture with this:

"Of all of the known forces, gravity is probably the one with which you have the most experience."

Edited by Davy_Jones
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12 minutes ago, Davy_Jones said:

Edit P.S. Also for everyone's reference, Prof. Lincoln opens the same lecture with this:

"Of all of the known forces, gravity is probably the one with which you have the most experience."

This is just semantics, the use of the term force in certain situations is to grant the reader/listener context of the scenario.

For example one might say "The force of gravity is nothing more than the curvature of space-time" You may use such a sentence to very simply describe the GR model of gravity to someone learning about gravity.  

So it is relevant to ascertain what the accepted definition of what a force is, however this may also depend on context and language used, as already been pointed out previously in this thread.

Professor Lincoln appears to have a clear understanding and belief of what the "force" of gravity is, be interesting to see his take on how this fits in with the quantum model. 

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22 minutes ago, Davy_Jones said:

Some of you may be familiar with the wonderful lecture series produced by "The Teaching Company" (aka "The Great Courses", I think).

Right now, by chance, I'm going through their course entitled "The Evidence for Modern Physics: How We Know What We Know" presented by professor Don Lincoln.

No I have not come across this one.

Is it online and do you have a reference ?

I do agree that studying the History and of Science and the Philosophy of Science can help understand the subject of Science itself, particularly looking at 'what was known at a particular time/stage and what thinking did it lead to' .

Some Scientists (eg Millikan) , some Science Historians (eg Sarah Dry) and Some Philosophers (eg Berkson) and some Mathematicians (eg John Derbyshire)  have been able to write briiliant expositions looking at these particular parameters.

 

Were you going to respond to my previous post ?

 

Edit, I just noticed that you provided a link to a rather expensive commercial site that seems more interested in making money than disseminating Science.

Edited by studiot
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10 hours ago, TheVat said:

So,  have to ask,  is string theory physics?  Or,  because we don't know to what degree it might describe the real world,  is it a theoretical framework that lies on the borderlands of metaphysics? 

String theory seems to describe a landscape of possible universes,  most of which intelligent life can never behold.   At least, with Davy's long-fingered lemurs,  we can go to Madagascar and look at quite a few of them.  (careful,  they will steal your glasses)

String theory has a model, but not much in the way of experimental confirmation thus far. It's physics, but not yet an actual theory in the scientific sense of the word - as beecee noted above, it's more properly termed an hypothesis.. It's a work in progress. 

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@studiot

Hey, it works! :)

Thanks for the tip! (Now all I need to do is master the quote function)

 

"You also seem to be more au fait with Philosophy authors or scientists discussing the philosophy of science."

Yes, that's right. The bulk of my reading is in the philosophy of science.

 

"As such have you heard of Berkson ? He has written a philosophical book on this subject"

No, I don't think I've heard of him. Sounds like the kind of thing I'd enjoy. Alas, I'm not allowed in the local uni library for the time being thanks to that darn virus. Grrr!

 

 

Re your post box example. My first thought (almost certainly wrong) is that the post box is red at all times. Of course, if you turn off the lights, or cover it with a white sheet, its redness will be concealed. I'd like to think more about this, though. Great example!

 

Re the final section of your post. What you seem to be saying, if I understand correctly, is that in certain circumstances it may be more expedient to bring Newtonian physics to bear on a problem, Einsteinian relativity in others. Not unlike Bohr's principle of complementarity, perhaps?

No argument there. But this is to treat theories as mere instruments. And again, there's nothing wrong in that per se.

Problems with inconsistency, such as the ones I've been alluding to in this thread, only arise when theories are treated realistically.

For example, if Theory A says that space and time are uniform and absolute, and theory B says that they are not, instrumental efficacy notwithstanding (both theories may work very well), it is not logically possible that both theories are true.

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35 minutes ago, Davy_Jones said:

Near the end of Lecture 15, "The Awesome Evidence for General Relativity", at the 28:30 mark, Prof. Lincoln perorates:

"I hope I've convinced you that there are very good reasons that general relativity has been very clearly validated. I mean I know that it's very weird to think of gravity as the bending of space and time, but it's just literally impossible to believe otherwise these days."


So, pace other contributors to the thread--perfectly entitled to their opinions--who have told us that no one knows what gravity is, or science cannot answer questions such as what gravity is, clearly, Prof. Lincoln does not share your skepticism.

The good professor is not only telling us what gravity is (It's the bending of space and time), but that to believe that gravity is anything other than the bending of space and time is not possible.

A tad hyperbolic if you ask me, but hey, I toss it out here for consideration. :) 

The professor is confirming the validity of general relativity. Any more is you reading something into it.

11 hours ago, Davy_Jones said:

One standard realist response to that one would be appeal to "Inference to the Best Explanation" (IBE)

Roughly (it comes in various forms): from a set of candidate explanations we are licenced to infer to the truth, or approximate truth, of the best among them.

How do you empirically determine the "best" explanation without invoking philosophy or other assumptions?

 

 

11 hours ago, Davy_Jones said:

 Edit P.S. Other fairly standard realist responses would look something like the following:

"If a theory is empirically adequate (i.e. saves the phenomena), moreover, yields new and surprising predictions then we have good reason to believe that it is true"

William Whewell, meanwhile, would speak of a "consilience of inductions" conferring epistemic warrant on a theory, i.e., good reason to believe that it is true.

"True" here means valid. i.e. we have confidence that the theory can be applied and give god answers. But it's still all about behavior and observation, and not about any underlying reality.

 

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28 minutes ago, Davy_Jones said:

For example, if Theory A says that space and time are uniform and absolute, and theory B says that they are not, instrumental efficacy notwithstanding (both theories may work very well), it is not logically possible that both theories are true.

Cf. Ptolemaic vs Copernican cosmology.

 

Both theories work well (i.e. yield accurate predictions) for certain purposes, e.g. navigation. You could navigate your way to Australia using either one, or so I'm told.

Given, however, that the two theories make logically incompatible claims, it is not possible that both are true.

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30 minutes ago, Davy_Jones said:

For example, if Theory A says that space and time are uniform and absolute, and theory B says that they are not, instrumental efficacy notwithstanding (both theories may work very well), it is not logically possible that both theories are true.

Not sure this is relevant, but what about wave/particle duality.

Your appeal to logic should be replaced by an appeal to rational thinking, which has much wider applicability.

For example my red post box.

 

The box is red because the enamel coat reflects incident red light and absorbs the rest.
So when illuminated by a light source that includes red light the box appears red otherwise it does not reflect any light and so appears black.
Normally light sources such as the Sun or car headlights include red light so showing the box as red.
Sodium street lights do not contain red, they contain only a particular shade of yellow.
So illumination by a sodium street light will show the box as black.

7 minutes ago, Davy_Jones said:

Cf. Ptolemaic vs Copernican cosmology.

 

Both theories work well (i.e. yield accurate predictions) for certain purposes, e.g. navigation. You could navigate your way to Australia using either one, or so I'm told.

Given, however, that the two theories make logically incompatible claims, it is not possible that both are true.

Yes I agree that the two theories have underlying compatibilities, but so what if what you actually want to do is navigate to Australia?

Navigators choose the geocentric theory as the most convenient for calculation, although they know it to contain a false premise.

But there are other possibilities for two theories.

The more complicated theory may actually reduce to the simpler one in certain circumstances, which is the case with GR and Newton.
In the case of statics (my dam for instance) GR and Newton are identical.

 

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@swansont

(Pardon my clumsiness with the quote function)

 

"How do you empirically determine the "best" explanation without invoking philosophy or other assumptions?" - swansont

 

You don't. The explanatory power (along with simplicity, etc.) of a theory is what's known as a non-empirical epistemic virtue. As I said earlier, strict empiricists will have no truck with this; the only epistemic virtue, on their account, is fit with the facts. (sounds a lot like you, sir)


Now, you may or not like it yourself, but many scientists routinely invoke explanatory goodness as a reason for believing some theory or other. Try asking Richard Dawkins, say, why we should believe the theory of evolution. You're likely to hear something like this (and I paraphrase):


"The theory of evolution provides the best explanation for all the empirical data we have. It provides a far better explanation than the theory of special creation."


(and the tacit inference is: explanatory power confers epistemic warrant; explanatory goodness is a reason to believe a theory. Otherwise why mention it at all?)

 

 

 

" "True" here means valid. i.e. we have confidence that the theory can be applied and give god answers. But it's still all about behavior and observation, and not about any underlying reality." -  swansont

 

Again, you continue to speak as if "Ask any scientist and they'll tell you the same thing". I repeat, scientists are a heterogeneous bunch; they say all manner of things about the aims of science.

There are, of course, scientists who believe as you apparently do: science is not in the business of getting at an underlying reality; the job of science is to "save the appearances" and stop right there! E.g.

Quote

Thus a true theory is not a theory which gives an explanation of physical appearances in conformity with reality; it is a theory which represents in a satisfactory manner a group of experimental laws. A false theory is not an attempt at an explanation based on assumptions contrary to reality; it is a group of propositions which do not agree with the experimental laws. Agreement with experiment is the sole criterion of truth for a physical theory.

- Pierre Duhem 

 

Meanwhile, in the red corner, here's another scientist who feels otherwise. The job of science, difficult though it may be, is to to go beyond mere appearances (the outside of the watch) and try to get at that underlying reality (the inner mechanism).

Quote

Physical concepts are free creations of the human mind, and are not, however they may seem, uniquely determined by the external world. In our endeavor to understand reality we are somewhat like a man trying to understand the mechanism of a closed watch. He sees the face and the moving hands, even hears its ticking, but he has no way to open the case. If he is ingenious he may form some picture of a mechanism which could be responsible for all of the things he observes, but he may never be quite sure his picture is the only one which could explain his observations. He will never be able to compare his picture with the real mechanism and he cannot even imagine the possibility or the meaning of such a comparison.

- Albert Einstein 
 

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3 minutes ago, Davy_Jones said:

Now, you may or not like it yourself, but many scientists routinely invoke explanatory goodness as a reason for believing some theory or other. Try asking Richard Dawkins, say, why we should believe the theory of evolution. You're likely to hear something like this (and I paraphrase):


"The theory of evolution provides the best explanation for all the empirical data we have. It provides a far better explanation than the theory of special creation."


(and the tacit inference is: explanatory power confers epistemic warrant; explanatory goodness is a reason to believe a theory. Otherwise why mention it at all?)

Believing a theory is not the normal description; in this case its because you have a non-scientific alternative that relies solely on belief. Notice that your quote does not actually cite belief.

The theory works whether you believe in it or not, and it's a good theory because it works - it matches observation and because of its strong explanatory and predictive powers. If there was a competing theory one could objectively compare them. Lamarckism, for example, was discarded because it lacks a mechanism for it to work. Not working = bad

Nothing about that lays claim to revealing realty. But the models and mechanisms of evolution aren't the examples that are most relevant. I argue that would be physics, and the reason that we know physics isn't trying to describe reality is because physics itself admits that it's making stuff up to make good models. Nobody claims that electric field lines physically exist. Phonons are quantized vibrational modes of a structure - not physical particles that exist independent of that structure. Electron holes are the absence of electrons, not some particle that exists on its own. These things aren't real, physical entities. They are calculational and conceptual aids to modeling behavior.  

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20 minutes ago, swansont said:

Believing a theory is not the normal description; in this case its because you have a non-scientific alternative that relies solely on belief. Notice that your quote does not actually cite belief.

 

First quote I could find . . .

[...] That phenomenon is conversion. Max Planck is often quoted to the effect that 'new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it'. A similar sentiment was expressed a half-century earlier Harvard's Professor Joseph Lovering, when he told his students that there are two theories of light, the wave and the corpuscular. Today, he is said to have remarked, everyone believes in the wave theory; the reason is that all those who believed in the corpuscular theory are dead. There is a measure of truth in such statements, as we all know, and yet a new scientific idea does win adherents, and even convinces some opponents, as has been seen in many examples throughout this book.

- Revolution in Science, J. Bernard Cohen, pp 467-468

 

Don't make me go searching through the forums for members believing such-and-such a theory. Pleeeeeaaaase!!

 

 

20 minutes ago, swansont said:

Nothing about that lays claim to revealing realty. But the models and mechanisms of evolution aren't the examples that are most relevant. I argue that would be physics, and the reason that we know physics isn't trying to describe reality is because physics itself admits that it's making stuff up to make good models. Nobody claims that electric field lines physically exist. Phonons are quantized vibrational modes of a structure - not physical particles that exist independent of that structure. Electron holes are the absence of electrons, not some particle that exists on its own. These things aren't real, physical entities. They are calculational and conceptual aids to modeling behavior.  

 

If no one believes these things are real, as you claim, why do I keep hearing--every few months or so it seems--that some new subatomic particle has been discovered?

How can that which is not real be discovered?

Prof. Lincoln again (our friend from above):

Quote

Dr. Lincoln’s research has been divided between Fermilab’s Tevatron Collider, until its close in 2011, and the CERN Large Hadron Collider, located outside Geneva, Switzerland. The author of more than 1,000 scientific publications, his most noteworthy accomplishments include serving on the teams that discovered the top quark in 1995 and confirmed the Higgs boson in 2012. 

 

Edited by Davy_Jones
aesthetics
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18 minutes ago, Davy_Jones said:

Don't make me go searching through the forums for members believing such-and-such a theory. Pleeeeeaaaase!!

Wouldn't that be off topic anyway ?

:)

 

27 minutes ago, swansont said:

Electron holes are the absence of electrons, not some particle that exists on its own.

These are a particularly poignant example because they are endowed with mass. This 'type' of mass is called effective mass in this case and is a sort of inertial mass.

And of course you can't really discuss gravitation without gravitational mass.

It is one of those mysteries that Science has not managed to answer

How does gravitational mass come to accord exactly with inertial mass.

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