Reductionism: Physics-Chemistry-Biology

Most biochemists don't know enough physics to discuss optical rotation sensibly.

For one, I'm not a biochemist. For another, any kind of chemist knows enough to discuss optical rotation a lot more authoritatively than you. I'll point that out below.

It's really quite simple; you see, the electrons in the outer shells absorb photons that have the same spin chirality they do, and don't absorb ones that don't; and you can only measure spin on one axis at a time. So each one is either up or down, compared to the electron, and if it's down, it gets absorbed. When the electron re-emits it, in order to conserve both spin and momentum, it has to emit it with a rotated spin axis. But that's only if it is in the same axis as the electron- otherwise, it doesn't absorb it.

Now consider that polarization is sorting by spin along one axis.

If that doesn't give you enough clues to figure it out, you'd better give up.

Pulling more stuff out of your sphincter again, schneib? Go here: http://www.phys.soton.ac.uk/quantum/lectures/lm6.pdf The link will take you to the real physics explanation of what's happening with polarization of light. It's got nothing to do with the chirality of photons, sap. What universe do you live in anyway?

I absolutely know that all biochemists can't be that stupid.

Well, there's at least one thing that you absolutely know, then.

Now, let's get back to your original point, shall we? 'Splain to all of us how sterochemistry can be completely described using physics. We're all getting a little impatient, schneib. This time, try not fabricating data. You're too easily caught.
 
Yes. More theoretical physics promulgated at describing empirical observation. Nice.

I don't understand what you're trying to get at here.

That wasn't the argument being misrepresented by schneibster, though. He wrote that one could predict optical rotation and many other physical traits of molecules strictly from the physics of bonding and knowledge of atomic orbitals.

Yes, you can.

Maybe he'll show up soon with another made-up book about this very exact thing from his Fantasy Collection.

That book isn't made up. I don't own it personally, but I've met Walter Harrison (the author) and talked with him about the exact sort of stuff Schneibster described in that book, and he even recommended I take a look at it for that reason (though I haven't gotten around to it yet).

Pulling more stuff out of your sphincter again, schneib? Go here: http://www.phys.soton.ac.uk/quantum/lectures/lm6.pdf The link will take you to the real physics explanation of what's happening with polarization of light. It's got nothing to do with the chirality of photons, sap. What universe do you live in anyway?

I'm afraid you're wrong, and the reason you're wrong is that there's more than one equivalent description of the physics involved. Yes, optical rotation occurs in linearly polarized light. But linearly polarized light can also be expressed as a superposition of circularly polarized light with opposite chiralities. The rotation of the polarization axis of linearly polarized light is exactly the same thing as a shift in the relative phases of the two chiralities. And the absobtion and re-emission of one of those chiralities is exactly the sort of thing that leads to a relative phase shift. So your reference hasn't actually contradicted Schneibster's claim - it's just a different representation of the same thing.

This time, try not fabricating data. You're too easily caught.

I don't mind if you don't like Schneibster. Hell, to be honest I don't actually like him much myself. But trust me on this one: he knows a lot of physics.
 
I don't understand what you're trying to get at here.

Ziggurat, the "conversation" you stepped in the middle of is one where shneibster has concluded that all sciences stem from physics. That's all I'm getting at from that remark. There is nothing wrong with what you've written.

Yes, you can.

No, Ziggurat, you can't. Physics fails to do much of anything after the very simplest cases. There are many physical parameters that can be estimated from a structure but not all. Again, you're running into schneibster's pissing in the soup in that he claims that one can even calculate the texture of a molecule. Any chemist who's made anything can tell you that's wrong. Anyone who's seen a diamond and held a lump of coal in their hand will tell you that's just an enormous pile of crap.

That book isn't made up. I don't own it personally, but I've met Walter Harrison (the author) and talked with him about the exact sort of stuff Schneibster described in that book, and he even recommended I take a look at it for that reason (though I haven't gotten around to it yet).

No, the book is real. I've found it of sale on the web. (I had to look it up because the schneib likes to make up little facts here and there.) The made up stuff is that schneib claims to possess it and to have read it. From his claims and from the little I found regarding the contents of said book, his claims about the book are pure bunkum. To compound his lie, he later stated the book had no content concerning chemical bonding. That claim was ludicrous because he had posted the title to the book earlier and included the subtitle "The physicis of the chemical bond" (IIRC).

The book is not fantasy but what schneibster says about it is.

I'm afraid you're wrong, and the reason you're wrong is that there's more than one equivalent description of the physics involved. Yes, optical rotation occurs in linearly polarized light. But linearly polarized light can also be expressed as a superposition of circularly polarized light with opposite chiralities. The rotation of the polarization axis of linearly polarized light is exactly the same thing as a shift in the relative phases of the two chiralities. And the absobtion and re-emission of one of those chiralities is exactly the sort of thing that leads to a relative phase shift. So your reference hasn't actually contradicted Schneibster's claim - it's just a different representation of the same thing.

Well, if I'm wrong for that reason, so is schneibster. The article I linked to concerned itself with crystallographic light polarization. The mathematics were based on crystallographic tensors. That is not what occurs in chemical light polarization but it's the best I could do. Kindly post a better explanation of optical rotation by molecules in solution. That is, molecules that are free-floating and are not burdened by a crystal matrix.

I've asked for an explanation and all I'm getting from the physics crowd are allusions to possible explanations which serve me not at all. But, let's face it, the issue is a derail. Maybe it isn't to you but schneibster is using it to smokescreen the fact that he can't make his grandiose claims about physics stick.

I don't mind if you don't like Schneibster. Hell, to be honest I don't actually like him much myself.

I find schneibster's MO repugnant. I've run accross this type of person too many times in my career. On one hand, he's a scientific bully who will try to embarass the other party into submission if they disagree with him or force him out of his comfort zone. On the other hand, he's also the know-it-all who would rather make up facts on the spot than admit there's something he doesn't know. I suspect he means well but he may not appreciate that both of these practices ultimately drive people away from science and into woo-ville. As a matter of fact, a made-up fact can be the basis of someone's distrust of science.

Frankly, I'd rather have him on the other side. (As a matter of fact, I usually find people like him on the other side and I am pretty good at exposing them for the fools they are.)

But trust me on this one: he knows a lot of physics.

I suspect he knows a fair bit of physics. How much and where it ends are, to me, unknown. Frankly, I'll get my physics from more reputable sources.
 
1) Measure the optical rotation of a pure solution, using a polarimeter, one enantionmer will have a + value, and the other a - value, a racemic mixture will show no optical rotation.

that's the one i wanted. inasmuch as optics isn't chemistry, i think you might just yield to physics coming in here. not in a "rule, explain, govern" way, but more along the lines of Herschel's "sciences working together if they are to do anything real" way.

John Herschell Discourses (#183):
It can hardly be pressed forcibly enough on the attention of the student of nature, that there is scarcely any natural phenomena which can be fully and completely explained in all of its circumstances, without the union of several, perhaps all, the sciences.

not that much has changed since 1830; it may be useful to note that physics envy of those who study "theories of (the) very little" seem less within physics itself than between physics and the other sciences, hard and soft. then again,it might not be.
 
Actually, I would agree with you and have argued for MR on this thread

understood. i think we are in general agreement.

we could talk about in principle vs in practice, and might even get Schneibster to agree, if perhaps only by destroying the distinction between the sciences along the way... but i'd prefer an alternative leading question...

Under MR, neither (completely) reduces. Under OR, both (pointlessly) do.

even under OR, do you believe science (or "Physics") reduces to maths, without a trivial (circular) definition of mathematics as whatever language science uses?

need a skeptic believe in isomorphism between theory and phenomena, even as a goal? and if not, might there not be more to science than maths, even if that other will eventually be claimed under maths, assuming we are smart enough to construct it?
 
who resent mathemeticians, who are just angry that they can't find dates.
No, the mathematicians resent philosophers, because after all math is just logic writ large.

It's the philosophers who can't find dates.

:D
 
This has to be the most bizzare argument I've ever seen. And I've been to the conspiracy sub-forum.

Everything is physics. This does not mean that physics is everything.
I'm with you, man. I can't follow this argument at all. Every time they say chemistry isn't reducible to physics, I want to say, "You mean chemistry isn't about atoms?"

It's all atoms. If it's strings under the atoms, then it's all strings. How is this not self-evident?

And how is not equally self-evident that studying the properties of individual attoms will be remarkably limited at predicting the behaviour of brazilions of atoms?

I keep expecting someone to huff and puff and cry, "I bet you think mind reduces to brain, you big mean ole reductionist!"
 
However, no one can review his postings in this thread and make any claim that the man exhibits the type of integrity that scientists should have if we, as a class, have any chance in prevailing against our detractors.
I can.

Let me put it this way: I don't know very much about chemistry or physics, but I know what Schnieby's argument is. I understand his point.

On the other hand, I have no idea what your point is. Are you arguing that chemistry is useful and valuable? Well, nobody ever suggested otherwise. Are you arguing that one can be a good chemist without studying hardly any physics? Well, nobody suggested otherwise. Are you arguing that the models we use to understand aggregate interactions of molecules are necessarily different than the models we use to study individual molecular interactions? But nobody suggested otherwise. Are you arguing that the shorthand approximations of chemistry are more socially/practically/morally useful than the less approximate but denser calculations of physics? Well... I'm not sure anybody has opposed that, even.

What you seem to be arguing is that chemistry is equal to atomic interactions plus some interactions that cannot be explained by atomic interactions. But that's so wooish I can't believe that is what you actually mean.

So really, I have no idea what your argument is. Except that you feel slighted by Schnieby.

:huh:
 
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Let me put it this way: I don't know very much about chemistry or physics, but I know what Schnieby's argument is. I understand his point.

Please do tell. As he resorted to making up evidence for it, he himself may not understand it well either. Please paraphrase.

What you seem to be arguing is that chemistry is equal to atomic interactions plus some interactions that cannot be explained by atomic interactions. But that's so wooish I can't believe that is what you actually mean.

Not at all. You seem to misunderstand completely. Schniebster has taken the position that chemistry is reducible to physics. Physics being defined as that which physics knows about atomic and molecular bonding/orbital modeling today, this minute. Did you not catch that? He cited a real book to back this up but made up the contents.

Several posters on this thread take the facile view that everything is reducible to physics because they define physics as everything. Pretty intelligent stuff, huh? Don't believe it? You just agreed with one in your previous post. That's an amazingly erudite view of science that, as all things are made of atoms, and the study of atoms is physics (really only in physicists' minds is this the case) then everything is physics. If you agree with that point of view then literature is physics also and you can quit reading now.

So, another poster and I have been posing the question of stereochemistry to schneib and he's stuck. He can't explain it and neither can any of the other physicists visiting this thread. Stereochemistry is a conformational phenomenon. That is, it depends not on which atoms are linked or nearby but how they are arranged in space. They have some unusual properties that physics as yet can't handle. Does it seem wooish to you now? Did you know about this before you posted? Did you know that your biochemistry is fairly well dependent on this phenomenon?

But, even if schneiby gets by that one, I've got others.

I have no doubt that physics sooner or later will decipher this phenomenon. Even then, physics is still trying to deal with modeling anything beyond deuterium. There are physicochemical models for a few physical properties of molecules but not many.

So really, I have no idea what your argument is.

Do you understand now?

Except that you feel slighted by Schnieby.

I would feel slighted by the guy if I respected him at all. He's just a blowhard. I'm more disappointed in the other physicists who know him who haven't called him on his mistatements previously. Maybe it's only chemists who self-police?
 
understood. i think we are in general agreement.

we could talk about in principle vs in practice, and might even get Schneibster to agree, if perhaps only by destroying the distinction between the sciences along the way... but i'd prefer an alternative leading question...
Hunh? Mmmmfff, nice old dog, wags his tail when you say his name.

Probably, yes. Although I certainly wouldn't claim that all sciences are based on physics- at least not the way they're done now. ;)
 

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