Nature of astrophysics (9) - Empiricism, Extrapolation, Etc

[Aardwolf]

Aardwolf, a detailed examination of the confrontation of GR with experiment is really beyond the scope of this thread; would you like to start a new one, or add to an existing one, in the Electric Universe section? I'd be happy to comment further in such a thread.

This, however, is very relevant to this thread:

And lab-based = In a lab under lab conditions. I'm not sure why the term "lab-based test" could be ambiguous. Why refer to a lab if your not expecting a controlled experiment under laboratory conditions. Why else would you even use a lab? Would one use a lab and not have a controlled experiment?

What is "a controlled experiment"?

In the case of gravity - in the sense of the idea that it has to do with mass - control could mean different masses held at different distances, some version of the Cavendish experiement perhaps. There are, however, severe limitations to such (lab-based, controlled, experiments/tests); for example, to apply the results of any such to the Earth, say, or the galaxy SDSS J113428.35+002830.9, an extrapolation of many orders of magnitude is required. But even more than that, all labs are on, or very near, the surface of the Earth; even though there might, one day, be labs on the surface of Mars, say, or even billions of km from the nearest large solar system object, no one reading this post today (6th January, 2011) will be alive to read about labs doing Cavendish-type tests on gravity somewhere in SDSS J113428.35+002830.9.

Even such a test - conducted by an ET perhaps? - would still not be a fully controlled test! Why not? Because the value of G (assuming Newtonian gravity) cannot be controlled.

Going back to another example in the OP, forbidden lines in planetary nebulae. Many of those prominent in the spectra of such astronomical objects have never been produced in "a controlled experiment under laboratory conditions", yet their assignment - [OIII] 1s22s2p3 -> 1s22p4, say - is hardly ever (never?) challenged, and certainly there is no serious proposal for ever more exotic rock/water/air/etc samples to be tested, in the lab, in search of a new element (nebulium) that produces these lines.

Aardwolf, you seem to be saying that we cannot know how the universe works, much beyond the Earth's atmosphere, ever; are you?

In light of the detail behind this post, do you think its fair to comment "General Relativity has passed every lab-based test to date"?

As you have stated there are "severe limitations" to a genuine lab-based experiment, and that is all I am trying to point out. At best you could say "a few experiments may be supportive of general relativity but may be supportive of other similar phenomena". I wouldn't take umbrage with that comment if you wish to alter or qualify your earlier post.

[Nereid]

In light of the detail behind this post, do you think its fair to comment "General Relativity has passed every lab-based test to date"?

Yes.

As you have stated there are "severe limitations" to a genuine lab-based experiment, and that is all I am trying to point out.

And how is the existence of severe limitations inconsistent with "passed every lab-based test to date"?

At best you could say "a few experiments may be supportive of general relativity but may be supportive of other similar phenomena"

Hang on ... "General Relativity has passed every lab-based test to date" and "a few experiments may be supportive other similar phenomena" are, logically, unconnected, right?

I mean, the latter is, as far as I can see, essentially meaningless, isn't it? If, perchance, you meant something like "a few experiments may be supportive other theories in physics", then it'd be an example of the logical fallacy of false dichotomy, wouldn't it?

I seem to be missing something here; can you clarify please?

[Nereid]

But it should be clear that any discovery that required too big a change to the original hypothesis MUST be seen as a deficiency of that hypothesis and therefore it should be discarded, even if there is nothing to replace it with

Which rather begs the question "how does one decide what "too big a change" is?" Your thoughts, Biggins?

Also, if you've discarded a hypothesis, how do you decide what to do next?

The question is, who can predict better?

Again, another begged question: "how does one decide what "better" is?" Your thoughts, Biggins?

[Aardwolf]

In light of the detail behind this post, do you think its fair to comment "General Relativity has passed every lab-based test to date"?

Yes.

Then perhaps you should explain what you mean by lab-based as you didn't provide any previously apart from Chou et al. (2010) which is only 1. By every did you mean 1?

As you have stated there are "severe limitations" to a genuine lab-based experiment, and that is all I am trying to point out.

And how is the existence of severe limitations inconsistent with "passed every lab-based test to date"?

Because your post didn't originally mention there are severe limitations. If there are severe limitations to lab-based tests shouldn't you remove or qualify the "lab-based" part? Eg. say "passed every severely limited lab-based test to date" or "passed every test to date". That would be less misleading than what you originally proposed.

At best you could say "a few experiments may be supportive of general relativity but may be supportive of other similar phenomena"

Hang on ... "General Relativity has passed every lab-based test to date" and "a few experiments may be supportive other similar phenomena" are, logically, unconnected, right?

I mean, the latter is, as far as I can see, essentially meaningless, isn't it? If, perchance, you meant something like "a few experiments may be supportive other theories in physics", then it'd be an example of the logical fallacy of false dichotomy, wouldn't it?

I seem to be missing something here; can you clarify please?

It was just a suggestion that makes sense to me. Devise a better one if you prefer.

[Aardwolf]

But it should be clear that any discovery that required too big a change to the original hypothesis MUST be seen as a deficiency of that hypothesis and therefore it should be discarded, even if there is nothing to replace it with

Which rather begs the question "how does one decide what "too big a change" is?"

Well having the wrong sign is a good reason for discarding. For example, predicting that the expansion of the universe should be decelerating when observations show it as accelerating. Or having to add 90% of completely unobservable mass to the universe. Are they big enough?

EDIT - My bad, they actually they added roughly 90/10 = 900% of mass to the universe. Maybe that's a big enough change for you Nereid.

[Nereid]

Aardwolf,

As you probably know, cosmological models with no CDM and no 'dark energy' are inconsistent with a wide range of different astronomical observations, many verified independently (some multiple times).

Such cosmological models have indeed been 'discarded' (to use Biggins' term).

By the way, it might be a good idea to have a discussion on how best to use the words 'theory', 'model', and 'hypothesis', at least in astrophysics; it seems that there's a high chance of misunderstanding because different Thunderbolts Forum members use them with different, possibly incompatible, meanings.

[mharratsc]

Ms. Nereid said:

As you probably know, cosmological models with no CDM and no 'dark energy' are inconsistent with a wide range of different astronomical observations, many verified independently (some multiple times).

I would say that the Plasma Cosmology would be exempt from your sweeping "no CDM and no 'dark energy'" statement, as it seems to be very consistent indeed... at least for as long as I've followed it.

[Nereid]

I would say that the Plasma Cosmology would be exempt from your sweeping "no CDM and no 'dark energy'" statement, as it seems to be very consistent indeed

Do you mean Cosmology in the Plasma Universe: An Introductory Exposition, H. Alfvén, IEEE Trans. Plasma Sci. 18, 1990?

As far as I can see that is inconsistent with the observational results which can be described, in shorthand, as 'the Hubble redshift-distance relationship'. Do you know of any published papers which use this 1990 Alfvén paper's "Plasma Cosmology" as the basis for models, and which are consistent with all the published observational results relevant to 'the Hubble redshift-distance relationship'? If so, can you please provide references?

But perhaps you are referring to a different published Plasma Cosmology proposal; are you? If so, what (and what is your source)?

[mharratsc]

Actually, I was pointing out that 'plasma cosmology' is consistent across almost every observation, in that it is capable, in it's own way, of explaining datasets from an electrodynamic perspective.

Now, you may not agree with it. You may think it is in error. You might even be a champion of the current 'standard' paradigm.

But I say that the model itself is pretty consistent and has been able to be applied against numerous observations without needing 'tweaking'... unlike some cosmological models I know...

[Goldminer]

By the way, it might be a good idea to have a discussion on how best to use the words 'theory', 'model', and 'hypothesis', at least in astrophysics; it seems that there's a high chance of misunderstanding because different Thunderbolts Forum members use them with different, possibly incompatible, meanings.

Sorry Nereid, I don't care whose forum, lecture, column, or whatever communication, there is always the "high chance of misunderstanding because different listeners of what ever background will apply them with different, possibly incompatible, meanings."

This is something that writers and speakers must take into consideration when composing their thoughts. It isn't a perfect world. Different contexts will change the meanings even when "everybody agrees." Listeners will apply a different context than the writer ever conceived. But be my guest; discuss it to death.

As far as I can see that is inconsistent with the observational results which can be described, in shorthand, as 'the Hubble redshift-distance relationship'.

As far as I can see, Nereid, being "inconsistent with the observational results which can be described, in shorthand, as 'the Hubble redshift-distance relationship" is being in good company with Hubble himself, since even though he came up with the "principle," he was not comfortable with it. Halton Arp has blasted that one clear out of the park. Incidentally Arp and Hubble worked with each other early on. All the denigration of Halton Arp and his work is really grating around these Electric Universe ramparts, even if Arp himself does not endorse this EU view point. (In the opinion of at least 25 others and me.) The "Hubble redshift-distance relationship" is not some immutable law.

[Aardwolf]

Aardwolf,

As you probably know, cosmological models with no CDM and no 'dark energy' are inconsistent with a wide range of different astronomical observations, many verified independently (some multiple times).

Such cosmological models have indeed been 'discarded' (to use Biggins' term).

By the way, it might be a good idea to have a discussion on how best to use the words 'theory', 'model', and 'hypothesis', at least in astrophysics; it seems that there's a high chance of misunderstanding because different Thunderbolts Forum members use them with different, possibly incompatible, meanings.

I dont dispute other theories fail and are abandoned but you didn't answer the questions.

Is changing the sign of an effect or needing to add 900% of the mass of the universe a big enough change to a theory to justify its abandonment? If not what is big enough?

[Nereid]

As far as I can see, Nereid, being "inconsistent with the observational results which can be described, in shorthand, as 'the Hubble redshift-distance relationship" is being in good company with Hubble himself, since even though he came up with the "principle," he was not comfortable with it.

An analogy, if I may.

Einstein was not comfortable with quantum theory, and even developed a set of Gedankenexperiments to highlight his discomfort (google 'EPR paradox', for example). Yet he is, arguably, one of the fathers of that theory!

Einstein's discomfort had no effect whatsoever on the outcome of experiments designed to test quantum theory, so why should Hubble's discomfort have any bearing on whether the Hubble redshift-distance relationship is consistent with all relevant astronomical observations?

(and after his death experiments to test the EPR paradox became possible; the results? Universe 1, Einstein 0)

Halton Arp has blasted that one clear out of the park.

To quote a Thunderbolts Forum member known very well to you, Goldminer, prove it!

The "Hubble redshift-distance relationship" is not some immutable law.

Of course it isn't ... and I never said it was (not that what I say has any bearing).

However, it is fully consistent with all relevant objective independently verified astronomical observations (at least as far as I know).

[Nereid]

Now, you may not agree with it. You may think it is in error.

So, to be clear, it's not that I agree with you (or don't agree with you); rather, it's that I can't see anything to agree (or disagree) with.

If Alfvén's paper does not present "Plasma Cosmology", what does? Lerner's (now unaccepted) Wikipedia page?

But I say that the model itself is pretty consistent

What 'model' would that be, mharratsc?

and has been able to be applied against numerous observations without needing 'tweaking'

It has? In Goldminer's words, prove it!

[Nereid]

Is changing the sign of an effect

What sign?

or needing to add 900% of the mass of the universe

What mass?

a big enough change to a theory to justify its abandonment?

What theory?

[Aardwolf]

Is changing the sign of an effect

What sign?

Universe decelerated expansion / accelerated expansion

or needing to add 900% of the mass of the universe

What mass?

Dark Matter

a big enough change to a theory to justify its abandonment?

What theory?

Any one that needs to be amended to account for accelerated expansion instead of expected decelerating expansion and needs to add 900% of unobservable matter for the observable matter to behave within the limits of theory.

For now lets ignore any real theories and just discuss hypothetically. In your opinion, would those 2 changes be big enough to cause the abondonment of the theory? If not, hypothetically, what would be big enough?