Jump to content

Is Gravity a Force?


Davy_Jones
 Share

Recommended Posts

32 minutes ago, Davy_Jones said:

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!!

 

I had thought that the difference between religious belief (belief despite there being no evidence) and other kinds (belief because of evidence) was apparent. The equivocation is why some people try to avoid using the word. The belief referenced in your quote is not religious belief, but the use with regard to creationism is.

I apologize for overestimating the situation.

Link to comment
Share on other sites

1 hour ago, Davy_Jones said:

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.

Yes different scientists often express apparently different views, but ask them both (all) to comment on exactly the same circumstances and they will most likely say the same thing. That 'thing' may be later found to be incorrect and Science as a whole will incorporate the new knowledge and no one would then support a contradictory view. For example there was general concensus that life could not exist and develop around the deep ocean geothermal vents, yet no one would deny that possibility today.

Edited by studiot
Link to comment
Share on other sites

@studiot above

Well, swansont and myself were talking about the aims of science. Swansont is telling us, it seems, that science does not try to get at underlying reality. Is that right, sir?

Are you (or swansont) seriously suggesting that all scientists in all times and all places have exactly the same view about the aims of science?

I've an idea: why don't we just ask them! :)

Edited by Davy_Jones
spring cleaning -- added a li'l bit
Link to comment
Share on other sites

6 minutes ago, Davy_Jones said:

Are you (or swansont) seriously suggesting that all scientists in all times and all places have exactly the same view about the aims of science?

No, of course not. How do you get from what we said to this?

 

Link to comment
Share on other sites

12 minutes ago, Davy_Jones said:

@studiot above

Well, swansont and myself were talking about the aims of science. Swansont tells us that science does not try to get at underlying reality.

Are you (or swansont) seriously suggesting that all scientists in all times and all places have exactly the same view about the aims of science?

I've an idea: why don't we just ask them! :)

That's a cheap trick.

I didn't say 'all' and I didn't imply they would say exactly the same thing, I stated that the circumstances would have to be exactly the same

The aims of scientists at all times and in all places is to too wide ranging and multipartite to be a useful measure of anything.

 

All to often I find Philosophical discussion lacking because it tries to tar too many monkeys with one brush and ends up with a paradox.

 

Edited by studiot
Link to comment
Share on other sites

3 minutes ago, swansont said:

No, of course not. How do you get from what we said to this?

Because on the previous page, while speaking generically about scientific theories. I 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.

 

To which you replied

"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.

 

So, just to be clear, what you're saying is that in your opinion scientific theories are not about any underlying reality, that's not the business/aim of science . . . though other scientists may have different ideas?

Given that the final clause (in red) was presented as an unqualified blanket assertion (and not a personal opinion), I took it to be just that.

Link to comment
Share on other sites

31 minutes ago, Davy_Jones said:

So, just to be clear, what you're saying is that in your opinion scientific theories are not about any underlying reality, that's not the business/aim of science . . . though other scientists may have different ideas?

This is different from 

Quote

all scientists in all times and all places have exactly the same view about the aims of science

One is asking about science, and the other is asking about scientists.

Scientists are free to do things other than science, in this case metaphysics or some other philosophy, and some of them do. I am in no position to say they should or shouldn't.

But people looking at the fundamental nature of the world are doing metaphysics, whether they explicitly admit it or not. (similar to the fact that some of what I do is engineering, even though I am a scientist. Disciplines blend together in many ways)

Link to comment
Share on other sites

@swansont

Re above

You did say on the previous page . . .

"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."

 

Given that--on your account-- "we know physics isn't trying to describe reality" and that physics "makes stuff up", how exactly are we to understand an announcement such as, say, "The top quark was discovered in 1995"?

Something unreal was discovered? The top quark has been discovered by physicists dabbling in metaphysics on their day off?

(I asked on the previous page. You didn't answer.)

Now, if the top quark has indeed been discovered, and it is real, would it not be fair to say that physics has added to our knowledge of reality, we have a better understanding of reality now thanks to physics, our description of reality is more complete than it hitherto was, or some such locution?

Edited by Davy_Jones
added a sentence "dabbling"
Link to comment
Share on other sites

12 minutes ago, Davy_Jones said:

Now, if the top quark has indeed been discovered, and it is real, would it not be fair to say that physics has added to our knowledge of reality, we have a better understanding of reality now thanks to physics, our description of reality is more complete than it hitherto was, or some such locution?

It maybe fair to say, we have a different understanding; but more complete is a question for tomorrow. 

Link to comment
Share on other sites

4 hours ago, Davy_Jones said:

 

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.....


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....

I have Don's email -- he was the resident physics expert at my erstwhile science forum for a decade.    Would you like me to invite him here to comment?   

Link to comment
Share on other sites

4 minutes ago, Davy_Jones said:

Given that--on your account-- "we know physics isn't trying to describe reality" and that physics "makes stuff up", how exactly are we to understand an announcement such as, say, "The top quark was discovered in 1995"?

Something unreal was discovered?

(I asked on the previous page. You didn't answer.)

Now, if the top quark has indeed been discovered, and it is real, would it not be fair to say that physics has added to our knowledge of reality, we have a better understanding of reality now thanks to physics, our description of reality is more complete than it hitherto was, or some such locution?

Something with a certain behavior which we call the top quark was discovered.

Generally, discussions about this do not split hairs about whether or not we are searching for reality, though there are some good discussions on the bad habit of reifying these things in physics. Mermin's "What's Bad About This Habit?" is a prominent one.

 

Quote

 

When I was a graduate student learning quantum field theory, I had a friend who was enchanted by the reve- lation that quantum fields were the real stuff that makes up the world. He reified quantum fields. But I hope you will agree that you are not a continuous field of operators on an infinite-dimensional Hilbert space. Nor, for that matter, is the page you are reading or the chair you are sitting in. Quantum fields are useful mathematical tools. They enable us to calculate things.

 

What kinds of things? Trajectories in spark chambers, nuclear level diagrams, atomic spectra, tunneling rate in superconductors, for example. It’s wonderful that the same tool—fields of operators on Hilbert space—works for all those different purposes, but one should not confuse the tool with the reality it helps to describe.

 

 

Later on he quotes Bohr

Quote

“In our description of nature the purpose is not to disclose the real essence of the phenomena but only to track down, so far as it is possible, re- lations between the manifold aspects of our experience,” and “Physics is to be regarded not so much as the study of something a priori given, but rather as the development of methods for order- ing and surveying human experience.”

 

 

Link to comment
Share on other sites

1 minute ago, dimreepr said:

It maybe fair to say, we have a different understanding; but more complete is a question for tomorrow. 

"Discover" is what they call a "success verb". If the top quark has indeed been discovered, then our understanding of reality just increased by one ontological unit.

It's in the bank, so to speak.

2 minutes ago, TheVat said:

I have Don's email -- he was the resident physics expert at my erstwhile science forum for a decade.    Would you like me to invite him here to comment?   

What a name-dropper! :)

I mean yes pleeeeeeaaaaaase!!!!!

Link to comment
Share on other sites

 

One other aspect of the problems with thinking physics is telling us what reality is is that over its history we've found better and better descriptions of how nature behaves. So it's ludicrous to think that Newtonian physics described reality, when we know that it was supplanted by relativity and quantum mechanics, and we know that these models are incomplete, and it's likely we will have a better model at some point down the line.

Link to comment
Share on other sites

25 minutes ago, Davy_Jones said:

"Discover" is what they call a "success verb". If the top quark has indeed been discovered, then our understanding of reality just increased by one ontological unit.

It's in the bank, so to speak.

What happens when the "success verb" run's out?

Link to comment
Share on other sites

18 minutes ago, MigL said:

Davy_Jones has brought up the Ptolomaic vs Copernican systems and how they can both be used for navigation, but only one is 'true'.

A slight correction. What I actually said was:

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

Of course, neither is believed to be true nowadays.

Link to comment
Share on other sites

I have invited Dr. Don Lincoln, physicist and well-known science author, who works at FermiLab, and who was quoted in this thread here....

 

 

....to join this discussion.  If he declines, I will let you all know, so as not to leave you hanging.

Mr. Jones suggested I'm a name dropper - I can only add that I have carefully not mentioned my long-ago acquaintance with Isaac Asimov, which I humbly offer as evidence to the contrary.  :-)

Link to comment
Share on other sites

9 hours ago, swansont said:

 

One other aspect of the problems with thinking physics is telling us what reality is is that over its history we've found better and better descriptions of how nature behaves. So it's ludicrous to think that Newtonian physics described reality, when we know that it was supplanted by relativity and quantum mechanics, and we know that these models are incomplete, and it's likely we will have a better model at some point down the line.

I repeat once more, you are perfectly entitled to your opinion that physics is not about describing reality. That is what you're saying, right?


Indeed, in your antirealist corner stand some of the very finest physicists, including Niels Bohr whom you quoted earlier.


My only animadversion is that every time you say such things, they are never qualified by a humble "in my opinion" or "of course not all physicists feel as I do".


Rather, what we see instead is invariably an unqualified "Physics is not about describing reality" as if a statement of undisputed fact is being presented, as if there is an unspoken "and that's all there is to it!", as if to say "ask any sensible physicist and they'll tell you the same thing". (at least that's how your peremptory pronouncements strike my ears)


This is what I find objectionable. Why, some of our more naive, wet-behind-the-ears members (if there are any) might even be beguiled into thinking that's the end of the story, there's nothing more to discuss.


That, of course, is not the end of the story. It is not a fact that all physicists feel as you do, that physics has no business describing, or at least trying to describe, reality.


Surely no one here needs reminding of Einstein's heroic realist stance against (what he saw as) the prevailing antirealist tyranny of Bohr, Heisenberg et al.


But he's six feet (depending on your frame of reference) under, you might well retort.


Among contemporary physicists, I can think of no more staunch realist than Steven Weinberg. One can barely turn the page of one of his popular expositions without tripping over antirealist bogeymen such as truth and reality. Here's a tantalizing teaser . . .

 

Quote

I know enough about science to know that there is no such thing as a clear and universal "scientific method". All attempts to formulate one since the time of Francis Bacon have failed to capture the way that science and scientists actually work. Still, under the general heading of scientific method, we can understand that there is meant a commitment to reason, often though not necessarily crystalized as mathematics, and a deference to observation and experiment. Above all, it includes a respect for reality as something outside ourselves, that we explore but do not create.

- Steven Weinberg (from "Facing Up", essay 4, "Confronting O'Brien")

 

Quote

All this [i.e. Kuhn's ideas] is wormwood to scientists like myself, who think the task of science is to bring us closer and closer to objective truth.

- Steven Weinberg (from "Facing Up", essay 17, "The Non-Revolution of Thomas Kuhn")
 

 

Clearly, not everyone shares your view that "we know physics isn't trying to describe reality".

 

 

7 hours ago, TheVat said:

Mr. Jones suggested I'm a name dropper - I can only add that I have carefully not mentioned my long-ago acquaintance with Isaac Asimov, which I humbly offer as evidence to the contrary.  :-)

Pfft! That's nothing. I once met (while in your beautiful country) the keyboard player from Sparks. Remember? The dude that looks like Hitler.

 

 

 

Edit P.S. 

Whoops! I just googled Steven Weinberg. Turns out he's six feet under too, as of a few weeks ago. RIP!

Edited by Davy_Jones
aesthetics, and added a P.S. and some more fiddling
Link to comment
Share on other sites

49 minutes ago, Davy_Jones said:

I repeat once more, you are perfectly entitled to your opinion that physics is not about describing reality. That is what you're saying, right?


Indeed, in your antirealist corner stand some of the very finest physicists, including Niels Bohr whom you quoted earlier.

In reality, and as others have explained, it is not an opinion, and it is not anti-realist, whatever slur that'ssupposed to project. We model what we see and what experiments define for us. Newtonian as successful as it was and is, was found to not be all inclusive...GR extended  those bounds of explanation and gives it in far more accurate details...GR itself is not the be all and end all of knowledge. It fails us at t+10-45th seconds after the BB, and fails us at the core of BH's. We do not know why mass/energy bends/warp/twists spacetime. We can only describe the effects of warped spacetime, and we know that effect as gravity.

The simple answer that you appear to see the need to reject, is that we still do not know the true nature of gravity.

49 minutes ago, Davy_Jones said:

Among contemporary physicists, I can think of no more staunch realist than Steven Weinberg. One can barely turn the page of one of his popular expositions without tripping over antirealist bogeymen such as truth and reality. Here's a tantalizing teaser . . .

I read Steven's book, "The First Three Minutes" and he also expressed his views that in time we may find a final theory of everything, but as yet that has not happened. Again physics models what we see and its success is in making successful predictions...eg: GR.  Physicists/scientists are not searching for reality and/or truth, whatever that is, but if it should accidently be found, then all well and good...no problems at all!

 

49 minutes ago, Davy_Jones said:

Clearly, not everyone shares your view that "we know physics isn't trying to describe reality" and that physics "makes stuff up"

And there are always Mavericks in every profession...some still reject GR, some reject the BB...Fred Hoyle comes to mind, an otherwise great astronomer/scientist, but wrong on this point. Christian/religious philosophers and pretend scientists still argue against the theory of evolution.

 

49 minutes ago, Davy_Jones said:

Surely no one here needs reminding of Einstein's heroic realist stance against (what he saw as) the prevailing antirealist tyranny of Bohr, Heisenberg et al.

Einstein was also wrong [his greatest blunder] on his static universe model, despite his model telling him that wasn't the case...hence the CC. With your reference, this is in regards to the HUP, is it not? I'm sure the great man if he was around today, would also admit error in that view.

Edited by beecee
Link to comment
Share on other sites

19 minutes ago, beecee said:

In reality, and as others have explained, it is not an opinion, and it is not anti-realist, whatever slur that's supposed to project.

Dude, antirealist is not a synonym for anti-science. Sigh!

Many of the finest scientists have held antirealist views.

Try this:

https://plato.stanford.edu/entries/scientific-realism/

 

 

19 minutes ago, beecee said:

I read Steven's book, "The First Three Minutes" and he also expressed his views that in time we may find a final theory of everything, but as yet that has not happened. Again physics models what we see and its success is in making successful predictions...eg: GR.  Physicists/scientists are not searching for reality and/or truth, whatever that is, but if it should accidently be found, then all well and good...no problems at all!

 

"All this [i.e. Kuhn's ideas] is wormwood to scientists like myself, who think the task of science is to bring us closer and closer to objective truth."

- S Weinberg

Physicists are not searching for truth, you say? Evidently, at least one is.

 

You think he's the only one?

Edited by Davy_Jones
Link to comment
Share on other sites

6 minutes ago, Davy_Jones said:

"All this [i.e. Kuhn's ideas] is wormwood to scientists like myself, who think the task of science is to bring us closer and closer to objective truth."

- S Weinberg

Physicists are not searching for truth, you say? Evidently, at least one is.

To bring us closer and closer, yep agreed and what I just said dude. But that doesn't change the fact that Physicists including Weinberg model observational and experimental data, and the success of those models is reflected on its successful predictions. Again, Physicists/scientists are not primarilly searching for reality and/or truth, whatever that is, but if it should accidently be found, then all well and good...no problems at all!

Link to comment
Share on other sites

11 hours ago, swansont said:

One other aspect of the problems with thinking physics is telling us what reality is is that over its history we've found better and better descriptions of how nature behaves. So it's ludicrous to think that Newtonian physics described reality, when we know that it was supplanted by relativity and quantum mechanics, and we know that these models are incomplete, and it's likely we will have a better model at some point down the line.

 

Oh, I agree it's ludicrous nowadays to think that Newtonian physics describes reality. Times have moved on.

But this is to miss the point that for two centuries or more, Newtonian physics might as well have been carved in stone. I daresay it was almost universally taken to be a faithful description of reality.

In other words, a great many physicists (I'm tempted to say the vast majority) did not find it remotely ludicrous that physics--at least sometimes, at least physics at its very best--can describe reality.

And I daresay many still do.

Looking forward to hearing what @TheVat's pal Don Lincoln has to say on all this.

 

 

Edit:

What you seem to be saying, swansont, if I'm understanding you right (please correct me if I'm wrong), is that we should not believe anything physicists have to say about unobservable reality (quarks, bosons, and all the rest). After all, it's all--on your account-- just models, and "making up stuff", and "we know physics isn't trying to describe reality".

Is this a fair representation of your position?

If it's any consolation, it's a position I'm not unsympathetic to myself.

I'm just afraid a riot might break out at any time. :)

Edited by Davy_Jones
getting a quote exactly right
Link to comment
Share on other sites

As my opinions and thoughts on the nature of Gravity have been split-off from a thread appropriately entitled "Is Gravity a Force ?", I have to wonder ...
What does the ideology of scientists, and the purpose of Science, which is being discussed at some length, have to do with the nature of Gravity ???

Link to comment
Share on other sites

21 minutes ago, Davy_Jones said:

Oh, I agree it's ludicrous nowadays to think that Newtonian physics describes reality. Times have moved on.

Even in Newton's day it wasn't thouhght to describe reality....Newton himself said words to the effect, that why it happened [the attraction between masses] no one knew...didn't he insinuate the  spiritual?

25 minutes ago, Davy_Jones said:

But this is to miss the point that for two centuries or more, Newtonian physics might as well have been carved in stone. I daresay it was almost universally taken to be a faithful description of reality.

 Not really, as I just illustrated. You appear to be reading something into factual accounts, that just isn't there.

34 minutes ago, Davy_Jones said:

In other words, a great many physicists (I'm tempted to say the vast majority) did not find it remotely ludicrous that physics--at least sometimes, at least physics at its very best--can describe reality.

And I daresay many still do.

It can, as I said, but that isn't the primary goal of physics and scientific theories. eg: we still do not know the true reality of gravity, other then feelings its effects when spacetime is curved in the presence of mass. And of course the question why mass/energy should curve spacetime.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.