Is the theory of punctuated equilibrium a gamechanger for evolutionary biology?

exchemist said:
At the most basic level one thinks of atoms with shells of electrons, at school level even sometimes picturing them in orbits as per the Bohr model.
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I was actually going to follow my post up with this. I knew nothing at all of orbitals at school, angular momentum, quantum numbers because I did not need to. I was taught about atomic mass, number and shells because I needed to know about "valency" how to balance equations.

Shells are not wrong- they work as a concept for 12 year olds.
 
Pinball1970 said:
I was actually going to follow my post up with this. I knew nothing at all of orbitals at school, angular momentum, quantum numbers because I did not need to. I was taught about atomic mass, number and shells because I needed to know about "valency" how to balance equations.

Shells are not wrong- they work as a concept for 12 year olds.
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No shells are not wrong at all, save that they are fuzzy clouds that interpenetrate. They give the right idea of layers that build up. But the Bohr model, with its planetlike orbits, is bad enough to be considered “wrong”, in my opinion. I really don’t think it should be taught, or not without a heavy disclaimer that it is purely symbolic.

It’s funny: although it only lasted a few years, because the problems with it were so obvious, it caught the popular imagination and has been used to symbolise almost anything “atomic” ever since:

1727788463970.png
 
Pinball1970 said:
I was actually going to follow my post up with this. I knew nothing at all of orbitals at school, angular momentum, quantum numbers because I did not need to. I was taught about atomic mass, number and shells because I needed to know about "valency" how to balance equations.

Shells are not wrong- they work as a concept for 12 year olds.
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What do you mean by "wrong"?

It's essential in any discussion of this type to clearly distinguish -- if you do at all (some people don't) -- between a theory or a model working, and a theory or a model being true or false, or at least candidates thereof. It's well known that both true and false theories work.

The Ptolemaic geocentric theory/model works. Predictions can be derived from it which, if so inclined, could be used for practical purposes such as navigation and surveying, indeed I believe it still is used for these purposes.

Just about any scientific theory/model you can name works -- to a greater or lesser degree -- in this sense. So does the Santa Claus theory - Little Johnny can derive from it the prediction that presents will be found around the tree on the morning of Dec 25 later this year. And he'll almost certainly be right!


Q1: In your view, is the Ptolemaic theory true or false? (Or do the terms not apply at all?)

Q2: In your view, is the Ptolemaic theory wrong? If so, what do you mean by this term? False? Our solar system isn't like that?

Q3: Is the Santa Claus theory wrong? Please elaborate. Why is it wrong? Because Santa Claus doesn't exist?
 
axocanth said:
What do you mean by "wrong"?
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The same way it's not "wrong" to teach Newtonian classical mechanics to A level students regarding projectiles. It works and you get the correct displacement, height, time and velocities using that method.
Teaching kids about valency regarding chemical reactions and balancing equations you do not need quantum mechanics.
 
Pinball1970 said:
The same way it's not "wrong" to teach Newtonian classical mechanics to A level students regarding projectiles. It works and you get the correct displacement, height, time and velocities using that method.
Teaching kids about valency regarding chemical reactions and balancing equations you do not need quantum mechanics.
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Ok. Next thing we have to be very clear about is the difference between the truth/falsity of observable predictions or consequences (same thing) that can be derived from a theory, and the truth/falsity of the theory itself. These are often confused.

Suppose, for example, we have a theory that posits an unobservable entity, or mechanism, or an array thereof, and suppose further that this theory yields only true predictions. Let us also suppose that the unobservable posits of the theory do not exist.

Should we assign this theory a value of true or false?
 
axocanth said:
Suppose, for example, we have a theory that posits an unobservable entity, or mechanism, or an array thereof, and suppose further that this theory yields only true predictions. Let us also suppose that the unobservable posits of the theory do not exist.
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There is a lot of supposing there and you are getting caught up on the meaning of words too much.
Word are a little bit malleable and context specific, we have seen this when physicists say Newton has been overthrown.

They are referring to specific things relating to his view of the universe.
His equations work just fine in their context, so by "overthrown" they do not mean every single thing he said has now been proven wrong.
 
@ Pinball (above)

Now, first of all, I'm not trying to force a choice of words on anyone; you're perfectly entitled to describe these things any way you like. I would say this though:

1. It seems perfectly appropriate to me to describe Newtonian physics as having been overthrown, and obviously many top notch physicists feel the same way.

2. I suspect the reason -- or one of them -- why you're reluctant to apply the word "overthrown" is, with all due respect, that you don't quite appreciate the difference between the ontology of a theory (i.e. what the theory says the universe is like), and the predictions which can be derived from that theory. The physicists I quoted do appreciate the significance, thus have no hesitation in using the word "overthrown".



Newton makes certain theoretical (i.e. unobservable) assertions about how our universe is. These theoretical assertions just are the theory (the predictions derived therefrom are not the theory). These core assertions include (i) space and time are uniform, independent and absolute, and (ii) there is an attractive force, which he calls gravity, which acts instantaneously over any distance according to a certain mathematical formula.

This, then, is Newton's ontology (= his theory). This, according to him, is the architecture and furniture of our universe.

Since Einstein, by and large (there may still be a few Newtonians out there), it is no longer believed that Newton's ontology (= his theory) describes how our universe really is. It is now believed that our universe is nothing like that. Physicists, by and large, now believe space and time are neither absolute, independent, nor uniform. They do not believe there is an attractive gravitational force at all. In other words, the architecture and furniture of our universe is nothing like Newton described.

Do you agree with this so far? (I can't emphasize enough, forget about the predictions which can be derived from the theory because they are not the theory). Any objections? If not . . .

Do you feel it is appropriate to say -- at least if we take Einstein seriously -- that Newton's ontology is all wrong, indeed that his core theoretical postulates do not even exist?

If so, do you feel it is appropriate to say that Newton's theory (= his ontology) has been overthrown? If not, why not? If you mention predictions again, I'll shoot you lol. The predictions are not the theory!


If you're still not persuaded (and that's ok), how about you give us an example of a scientific theory that, in your view, was overthrown, and explain why you think it is appropriate to speak of it being overthrown in this case?

Are there any?
 
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axocanth said:
1. It seems perfectly appropriate to me to describe Newtonian physics as having been overthrown, and obviously many top notch physicists feel the same way.
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Not my experience and that is why Newton is still taught as it is. Two things you do not mention enough, Newton is an approximation and it works in that way.
He said this, “I don’t know how gravity works. But I can calculate it and that should be good enough.”

It is good enough in its domain.

Einstein was wrong about an expanding Universe even AFTER he had published General Relativity. He was totally wrong, it is not only expanding it is accelerating. Did Hubble, Lemaitre ans Slipher overthrow Einstein? Well they proved him wrong, Perlmutter proved him wronger!

General relativity is still one of the most important theories in physics and it is still an approximation and he was totally wrong about the structure of the entire universe and his theory that describes it.
 
Pinball1970 said:
Not my experience and that is why Newton is still taught as it is. Two things you do not mention enough, Newton is an approximation and it works in that way.
He said this, “I don’t know how gravity works. But I can calculate it and that should be good enough.”
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Correction: The predictions which can be derived from Newtonian theory are an approximation (of the predictions which can be derived from Einstein's theory).

To say that Newtonian theory approximates Einsteinian theory is to say that absolute space and absolute time approximate a relativistic, non-absolute spacetime manifold. It is to say that an attractional force approximates the curvature of spacetime.

And I know of no one who says that. Do you?
 
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axocanth said:
To say that Newtonian theory approximates Einsteinian theory i
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Nope I did not say that, the approach and domains are different. Totally different approaches even though they were both wrong about a lot that went into their theories.
 
Listen to the master himself . . .


"We have another instance of far-reaching agreement between the deductions from two theories in Newtonian mechanics on the one hand, and the general theory of relativity on the other. This agreement goes so far, that up to the present we have been able to find only a few deductions from the general theory of relativity which are capable of investigation, and to which the physics of pre-relativity days does not also lead, and this despite the profound difference in the fundamental assumptions of the two theories"
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- Albert Einstein, "Relativity: the Special and General Theory" (2005), pp160-161



There is far-reaching agreement between the deductions (= predictions! ) of the two theories. The predictions of the two theories approximate each other (at the limit).

There is a "profound difference" in the fundamental assumptions of the two theories. The two theories are nothing like each other. They do not "approximate" each other.
 
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and

"For Einstein gravity was not a force it was a feature of the geometry of space time, this is a profoundly different approach."
 
Ok, so answer these first, please . . .

Q1. Are the predictions of the two theories similar (as the limit is approached) ?

Q2: Are the two theories similar?
 
Pinball1970 said:
Newtons View attachment 6185

Einstein GR View attachment 6187

Notice anything? That G? So not quite overturned then?
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Actually, as I understand it, in the 2nd expression G with suffices denotes elements of a tensor rather than the gravitational constant. However k on the right hand side is Einstein’s gravitational constant, which is indeed proportional to Newton’s G. So you are perfectly right that Newton’s constant survives in GR.
 
axocanth said:
Q1. Are the predictions of the two theories similar (as the limit is approached) ?
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I am not sure what you mean by limit. Yes the predictions will yield similar results for some scenarios.
axocanth said:
Are the two theories similar?
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No, I have stated that the approaches were different. The back drop w.r.t. the theory was also different as Einstein had published SR 9 years earlier.
 
Pinball1970 said:
I am not sure what you mean by limit. Yes the predictions will yield similar results for some scenarios.

No, I have stated that the approaches were different. The back drop w.r.t. the theory was also different as Einstein had published SR 9 years earlier.
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I suppose the "limits" involved are (i) relative velocities small compared to c and (ii) "weak gravitational fields" (suppose that means only slight curvature of spacetime). There's a discussion of this here: https://physics.stackexchange.com/q...eneral-relativity-exactly-how-wrong-is-newton. (You can see the first responder is quite incensed by the notion that Newton was shown to be "wrong", i.e. that his theory is "false".:))
 
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