When to use Special versus General Relativity?

[koti]

29 minutes ago, studiot said:

If gravity is present, space is 'warped' and GR is required.

 

27 minutes ago, swansont said:

If spacetime is sufficiently flat graviational effects can be ignored. We do this all the time.

If I make grilled cheese sandwiches I put ketchup on them and eat them. I do this all the time.

[StringJunky]

9 minutes ago, Strange said:

No. This looks like a good explanation: http://www.einstein-online.info/spotlights/geometry_force

See the section "Remains of gravity" where it discusses tidal forces.

Yeah, that one kills it. As they say, it cannot be transformed away. 

[beecee]

44 minutes ago, aramis720 said:

It is sometimes the case that theories become pedestalized to such a degree that anyone who tries to go through the normal channels is effectively shut down. Hence Beckmann's alternative approach. There are also a number of dissident physics journals created to mitigate this problem. Unfortunately, science isn't always entirely rational and funding, careers, groupthink, etc., can often prevent the most reasonable solutions from coming to the fore. Have you read Smolin's book The Trouble With Physics, looking in detail at why string theory is in his view a dead end, and yet consumed many physics careers for some time? 

Nothing is perfect, including science and the scientific methodology, but it is by far the best we have. While to some extent, sometimes alternative approaches,(particularly alternative to GR or the BB) are hard to get to see the light of day, that stems from the fact that theories such as GR have continually made successful predictions such as gravitational waves and even more recently, the orbital parameters of stars orbiting close to the Milky Way's SMBH. But again with the number of ongoing tests of our incumbent theories, and the number of young up and coming physicists that would dearly love to extend the parameters of the BB and/or GR, if anything was to surface and really shown to be more accurate then the incumbent, no amount of pedestalization, or stone walling, or attempts at shutting down, will ever be maintained for too long. String theory and/or any of its derivitives are in my opinion just in a hiatus, due to the fact that their validity is impossible to verify as we as yet do not have the technology to observe and/or measure at such scales....whether one of them proves to be a QGT remains to be seen. I see Beckmann  is an electrical engineer, and while that does not disqualify him, it still puts him behind the eight ball so to speak.

At this time the holy grail of physics is a validated TOE/QGT: A TOE/QGT that by definition will be more accurate then Einsteins GR, but you can also bet your short n curlies that it will also encompass GR and the BB itself.

[studiot]

9 hours ago, swansont said:

If spacetime is sufficiently flat graviational effects can be ignored.

I do believe that the OP specified exact three times within the first seven posts.

Therefore any approximation that disregards something on account of insignificance is not acceptable within the bounds of this thread and perhaps off topic?

[Strange]

15 minutes ago, studiot said:

I do believe that the OP specified exact three times within the first seven posts.

Therefore any approximation that disregards something on account of insignificance is not acceptable within the bounds of this thread and perhaps off topic?

As the OP is pushing a non-mainstream theory (to put it kindly) I think explaining why he is mistaken is completely on-topic.

[studiot]

1 hour ago, Strange said:

As the OP is pushing a non-mainstream theory (to put it kindly) I think explaining why he is mistaken is completely on-topic.

Yes of course you should explain why the strict exact Einstinian theory is not only better than the Beckmann one, but is also the best we have.

 

[swansont]

3 hours ago, studiot said:

I do believe that the OP specified exact three times within the first seven posts.

I don't see the word exact at all until you used it.

3 hours ago, studiot said:

 Therefore any approximation that disregards something on account of insignificance is not acceptable within the bounds of this thread and perhaps off topic?

Or one could explain how this is completely unreasonable, since no model is perfect. We would have nothing to discuss.

[studiot]

5 minutes ago, swansont said:

I don't see the word exact at all until you used it.

No he used the word strict or strictly, which I take to have the same meaning when taken in the context of his surrounding text.

[swansont]

3 minutes ago, studiot said:

No he used the word strict or strictly, which I take to have the same meaning when taken in the context of his surrounding text.

And strictly speaking no physics model is correct. But that's not how we do physics, so it's moot.

[aramis720]

On 8/25/2017 at 2:06 PM, beecee said:

Nothing is perfect, including science and the scientific methodology, but it is by far the best we have. While to some extent, sometimes alternative approaches,(particularly alternative to GR or the BB) are hard to get to see the light of day, that stems from the fact that theories such as GR have continually made successful predictions such as gravitational waves and even more recently, the orbital parameters of stars orbiting close to the Milky Way's SMBH. But again with the number of ongoing tests of our incumbent theories, and the number of young up and coming physicists that would dearly love to extend the parameters of the BB and/or GR, if anything was to surface and really shown to be more accurate then the incumbent, no amount of pedestalization, or stone walling, or attempts at shutting down, will ever be maintained for too long. String theory and/or any of its derivitives are in my opinion just in a hiatus, due to the fact that their validity is impossible to verify as we as yet do not have the technology to observe and/or measure at such scales....whether one of them proves to be a QGT remains to be seen. I see Beckmann  is an electrical engineer, and while that does not disqualify him, it still puts him behind the eight ball so to speak.

At this time the holy grail of physics is a validated TOE/QGT: A TOE/QGT that by definition will be more accurate then Einsteins GR, but you can also bet your short n curlies that it will also encompass GR and the BB itself.

We'll see. Two key points: if you subscribe to a Kuhnian notion of scientific revolutions, the change, when it does come, will be relatively rapid as the older guard dies off and the new guard recognizes the growing pile of anomalies/epicycles behind GR/SR (in particular, DM, DE and inflation), and then the history books will be re-written in such a way that the new approach will be made to look like it was a smooth path from the old approach. That is, if we believe Kuhn. Second, yes, generally new theories in physics and other fields include and transcend old theories. But not always. In my years of reading in this field, it's growing increasingly apparent to me that some kind of ether theory will be the TOE/QGT, and GR is in fact sometimes framed as a new kind of ether theory with the gravitational field as the new ether (though of course GR is not a TOE). Even Einstein adopted this ether language from about 1916-1924 (see Kostro's Einstein and the Ether for more on this). But I'm also of the view that the new ether approach can't be relativistic in terms of Lorentz invariance, as Einstein suggested his new ether was. Beckmann's is just one of many velocity-dependent approaches to gravity (see also Ghosh's book Origin of Inertia), and all this means is that there is some kind of background/ether/space that exerts dynamical effects akin to moving through air or water, but just far more of an attenuated medium. There are many lines of evidence suggesting that this kind of attenuated drag approach is accurate and far simpler than GR, but we are in my view stuck in the dogma of the allegedly background-independent approach of Einsteinian relativity for now and the foreseeable future. 

20 hours ago, Strange said:

As the OP is pushing a non-mainstream theory (to put it kindly) I think explaining why he is mistaken is completely on-topic.

I'm not pushing any theory here. My OP was simply asking about the application of GR vs. SR and then the discussion flowed naturally to related topics. That said, I'm happy to make it plain that I don't find SR/GR very convincing, for a variety of reasons relating to their very nonintuitive postulates and to the series of epicycles that have arisen around GR in particular to make it work within known empirical facts. 

17 hours ago, swansont said:

And strictly speaking no physics model is correct. But that's not how we do physics, so it's moot.

My broader point about SR was that it's good to realize that it has no strict application in the real world because it's an idealized theory. There are in practice always gravitational fields present, but yes of course we can often ignore them as negligible. But that said we should also realize that SR is built on an unfalsifiable tautology: that we know what an inertial frame is and can identify them. Einstein and Infeld acknowledge in their book The Evolution of Physics (p. 210) that the idea of an inertial frame is a "useful fiction," is "built on sand", and is tautological. Strong criticisms from the creator of SR!  

Edited August 27, 2017 by aramis720

[Strange]

1 hour ago, aramis720 said:

My broader point about SR was that it's good to realize that it has no strict application in the real world because it's an idealized theory. There are in practice always gravitational fields present, but yes of course we can often ignore them as negligible. But that said we should also realize that SR is built on an unfalsifiable tautology: that we know what an inertial frame is and can identify them. Einstein and Infeld acknowledge in their book The Evolution of Physics (p. 210) that the idea of an inertial frame is a "useful fiction," is "built on sand", and is tautological. Strong criticisms from the creator of SR!  

This is true of all theories. And will be true of whatever "replaces" GR.

[beecee]

5 hours ago, aramis720 said:

We'll see. Two key points: if you subscribe to a Kuhnian notion of scientific revolutions, the change, when it does come, will be relatively rapid as the older guard dies off and the new guard recognizes the growing pile of anomalies/epicycles behind GR/SR (in particular, DM, DE and inflation), and then the history books will be re-written in such a way that the new approach will be made to look like it was a smooth path from the old approach. That is, if we believe Kuhn. Second, yes, generally new theories in physics and other fields include and transcend old theories.

What anomalies do you see with GR? Considering that in recent times, it has become even more entrenched as its predictions are verified.eg: Gravitational waves, orbital motions of stars orbiting close to Sagitarius A. Of course GR has limited parameters and is non applicable at the quantum scale, just as any scientific theory has zones of applicability.

DM of course is necessary to explain anomalous rotation of stars in outer galaxies and was certainly originally a fudge factor: Since then of course more evidence has been forthcoming to support its existence.....http://chandra.harvard.edu/press/06_releases/press_082106.html To say that DM "disqualifies GR is like throwing the baby out with the bath water......GR is overwhelmingly supported by experimental and observational evidence, including what I have already detailed........DM works with GR and all we need to do is put an actual finger on it along with the observational evidence so far. 

DE is certainly a mystery as yet, but could possibly be the cosmological constant of Einstein fame, Again though it will take  observational and experimental evidence to over throw GR and/or having it falsified: Making claims with limited credentials in a book is not evidence. 

Quote

There are many lines of evidence suggesting that this kind of attenuated drag approach is accurate and far simpler than GR, but we are in my view stuck in the dogma of the allegedly background-independent approach of Einsteinian relativity for now and the foreseeable future. 

Again I'm pretty sure if there was any validity to what you seem to be claiming or this Beckmann blokes claims, the there would be a hoard of fully qualified physicists, conducting experiments, making observations, and doing tests for any real evidence of errors/anomalies in GR. And then of course as I have seen before, also many unqualified with various agendas also for whatever reasons trying to also unseat Einstein and SR/GR. http://www.staff.science.uu.nl/~hooft101/gravitating_misconceptions.html

It's also worth remembering the rushed mistaken claims of BICEP2, and who showed it to be wanting and the published findings questionable...It wasn't anyone writing a book, or claims on an open public forum, It was other professional scientists, physicists and cosmologists that showed it to be possibly false.

 

 

Edited August 27, 2017 by beecee

[swansont]

5 hours ago, aramis720 said:

 My broader point about SR was that it's good to realize that it has no strict application in the real world because it's an idealized theory. There are in practice always gravitational fields present, but yes of course we can often ignore them as negligible. But that said we should also realize that SR is built on an unfalsifiable tautology: that we know what an inertial frame is and can identify them. Einstein and Infeld acknowledge in their book The Evolution of Physics (p. 210) that the idea of an inertial frame is a "useful fiction," is "built on sand", and is tautological. Strong criticisms from the creator of SR!  

And my broader point is that you can say this about any model in physics. But that's not how we actually apply physics, so the objection is moot.

You are wrong in saying it is unfalsifiable. We can measure things well enough to be able to see if it matches with theory. We just can't do it to arbitrary precision. If time dilation ended up being linear in v, (or completely absent) we would see this quite easily. 

Physics is rife with useful fictions

[aramis720]

22 hours ago, Strange said:

This is true of all theories. And will be true of whatever "replaces" GR.

What do you mean? You think all theories are based on tautologies? Do you agree that tautologies, because they're unfalsifiable, are entirely unscientific? 

[swansont]

4 hours ago, aramis720 said:

What do you mean? You think all theories are based on tautologies? Do you agree that tautologies, because they're unfalsifiable, are entirely unscientific? 

It's quite likely Strange meant this about the "strict application to the real world". Relativity is not a tautology, and is not unfalsifiable. I see reports of attempts to falsify it on a fairly regular basis. None of them have succeeded thus far.

[studiot]

22 hours ago, swansont said:

You are wrong in saying it is unfalsifiable. We can measure things well enough to be able to see if it matches with theory. We just can't do it to arbitrary precision. If time dilation ended up being linear in v, (or completely absent) we would see this quite easily. 

Furthermore as our ability to increase that precision grows (eg the gravitational constant or charge on the electron) or as a result of change of base of measurement (eg temperature) we revise published tables of data.

In the first case just some numbers (coefficients) are (usually) slightly altered in an existing formula

In the second case the formule itself may be changed to suit.

I don't think anyone would consider that 'falsifying theory', just improving the structure of Physics.
 

The most dramatic case of this I can think of was correcting the mixup over atomic weights and atomic numbers and numbers of atoms in a given molecule by early chemists.

[swansont]

Further, to say something is unfalsifiable is to claim that there isn't an experiment that can be done that would test to see if some relationship of variables (i.e. a prediction) is correct. There are situations where this is true but it is laughably wrong here.

[aramis720]

On 8/27/2017 at 1:07 AM, swansont said:

And my broader point is that you can say this about any model in physics. But that's not how we actually apply physics, so the objection is moot.

You are wrong in saying it is unfalsifiable. We can measure things well enough to be able to see if it matches with theory. We just can't do it to arbitrary precision. If time dilation ended up being linear in v, (or completely absent) we would see this quite easily. 

Physics is rife with useful fictions

What other useful fictions do you see in today's physics? At what point does a useful fiction become just fiction? 

[swansont]

1 hour ago, aramis720 said:

What other useful fictions do you see in today's physics? At what point does a useful fiction become just fiction? 

Phonons are one example.

It's useful if it works.

[aramis720]

3 minutes ago, swansont said:

Phonons are one example.

It's useful if it works.

Ah, so you don't think physics is about explaining reality? For you, it's about useful calculation tools? This is a serious question and I think indicative of a deep split among certain physicists and philosophers. 

Also, would appreciate more than the phonon example since you suggested that physics is rife with useful fictions. 

[lakmilis]

On 26/08/2017 at 0:35 AM, beecee said:

Of course, and by the way Einstein is questioned every day by the experts in the field, which obviously Beckmann is not. As has already been conveyed to you, if anyone did have a hypothesis that either invalidated an incumbent theory, or explained more then the incumbent theory, that "anyone" would not be publishing it in a book...If he seriously had a workable hypothesis that did what he claimed, he would proceed by writing a proper scientific paper, for proper professional peer review.

I mentioned it the other day in another thread, that in my time on another forum, we had over a couple of years , four "would be's if they could be's" each claiming to have overthrown Einstein's GR, and each after much questioning and probing by other members, were found to have agendas...in three of those it was a closeted ID/religious agenda that finally surfaced. The impetus that drives these type is the fact that science has pushed back any need for any deity into near oblivion, and they are driven to try and expose the science, particularly SR,GR and general cosmology as in error. The fourth was just a down and out anti science nut. You may not have an ulterior motive, but as you have been informed, there is a proper procedure for anyone to go through, if they had anything of any consequence and were fair dinkum. Let me say that I see that chance as vanishingly small, as  relativity and the mathematical validation that goes with it, is rather complicated.

Ya.. that is exactly what I said about that plonker in the chair. Erm Stephen Hawkings or so.

[swansont]

6 minutes ago, aramis720 said:

Ah, so you don't think physics is about explaining reality? For you, it's about useful calculation tools? This is a serious question and I think indicative of a deep split among certain physicists and philosophers. 

Also, would appreciate more than the phonon example since you suggested that physics is rife with useful fictions. 

Since that's not the topic of the thread, perhaps you could use the search function to find one of the several threads where it's already discussed. You might run across a link to the excellent article by David Mermin where he goes into a great deal of detail.

then you can post there, or start a new thread.

[studiot]

5 minutes ago, aramis720 said:

Ah, so you don't think physics is about explaining reality? For you, it's about useful calculation tools? This is a serious question and I think indicative of a deep split among certain physicists and philosophers. 

Also, would appreciate more than the phonon example since you suggested that physics is rife with useful fictions. 

Oh for goodness sake, where are all the real world rigid bodies, inelastic collisions, frictionless surfaces, perfect mirrors, truly adiabatic thermal processes.......

 

[Strange]

... spherical cows ...

[J.C.MacSwell]

1 hour ago, studiot said:

Oh for goodness sake, where are all the real world rigid bodies, inelastic collisions, frictionless surfaces, perfect mirrors, truly adiabatic thermal processes.......

 

Is this "pick the one that actually exists"?