/sci/ - Science & Math

>>7610184
Undergrad biochem student here, learning about the subjects you are describing. I don't see why it's problematic. Yes, the models are approximations, but that's only because the quantummechanical functions are too difficult to solve (2nd order something or something, still have to learn why that's unsolvable, if anyone can explain it in some detail here that would be cool), so, going on experimental data we do geometric additions of their probability distributions. These approximations make sense with experimental data, thus we use it. This goes voor MO and VB. The other assumption, concerning the problem you have with the fact that electrons should be falling into nuclei and such. This doesn't happen because of thermodynamic properties that are intrinsic to the universe, being maximization of entropy and the subsequent minimization of energy. When two atoms interact, their electronic geometries interact, in this interaction, the intrinsic properties that I talked about above are determining the outcome of the interaction. Electrons shielding the nuclei from electrostatic force, effectively minimizing this force, while the charge interaction between the nuclei and the electrons is maximized is the outcome when you apply the minimal energy property that seems to be a law of nature. So it's all really just matter behaving under laws of nature, nlthing mysterious about imo, bjt maybe your problem is deeper than I believe it to be. I'm just undergrad ofcourse.

>>7610184
>What is quantum mechanics?

>>7610208
My prof went over this stuff on his 3rd lecture of year one. Its basic quantum mechanics. I dont claim to know the whole schrodinger equation but electrons behaving like waves solves OPs conundrums. Im not exactly a teacher, but I always just imagine the electron as a jiggly fluid if it helps.

You should've studied physics if you wanted to understand that. It's a bit sad, but it's true.
As a biochemistry student I share your pain.

>>7610403
I agree with this and if OP is really interested in the deeper mechanisms he should probably just pick up some good physics textbooks and start to work through them slowly but surely on the side. Something I want to do apart from biochem too.

>>7610184
Didn't you look at potential wells in gen./phys. chem?

>Why would two nuclei autistically decide that they need to stay within a fixed distance of each other?
It's more stable is not a cop out, energy minimization is fundamental concept in chemistry. Imagine if you threw a ball into a valley, it's obvious it would end up in the middle between the two slopes since gravity will accelerate it down until the point where the ball stays at the bottom (of course if you add energy to the ball it will oscillate on the slopes and eventually escape if you add even more energy).

Same thing happens in molecular systems. The systems minimize at a certain distance.

>Why don't they fall into the (positively charged) nucleus?
The valence electrons are doing the moving, the inner electrons repulse the valence electrons increasing energy.
>But what about hydrogen?
Nuclei are repulsive, electron potentials are share between both nuclei. Of course the more fundamental question is why doesn't the electron of a single hydrogen atom fall into its nucleus. You need to study more fundamental QM to understand it fully, but for now google the electron probability distribution of the 1S orbital.

If you want to understand how it works from a chemical perspective without studying (real) QM or molecular dynamics (about 0.5-1.5 years of study depending on your schedule) in detail look at the molecular thermodynamics chapter in "Introduction to Chemical Engineering Thermodynamics" by Smith, Van Ness, and Abbott.

>>7610184

You're basically asking "what is charge?" and "Why do charges interact the way they do?"

These are some of the most fundamental areas of existence. There are many ways to model them but it's also possible that the reason there isn't a good explanation is because it hasn't been discovered yet. Why don't you go and discovery it, OP?

Personally I'm a fan of mechanical models of the universe, more specifically ether-based models. But if you mention that at a university, everyone punches you in the dick. It's worse than religious-fanaticism when it comes to scientists and their hostility to modern-era ether models. By the way, an omnipresent ether has never been disproven.

>>7610464
*punches you in the dick*

>>7610464
No he's not, charge isn't the only force in molecular dynamics.

People want to punch you in the dick because you're retarded and talk about things you haven't studied yet.

>>7610184
>Saying "it's more stable" is a cop-out
Principle of least action, two atoms will tend to minimise their action. Which is means they will occupy whatever minimise their potential energy.

>Why don't they fall into the (positively charged) nucleus?

Stationary states. They're states in the atom where the electrons don't radiate away energy, which means they don't fall into the nucleus. More formally a stationary state is an eigenvector which is time independent leading which means that we had a state of definite energy.

>>7610464
What would an omni present ether model entail?

>>7610464
>By the way, an omnipresent ether has never been disproven.
https://en.wikipedia.org/wiki/Michelson%E2%80%93Morley_experiment

>>7610464
>By the way, an omnipresent ether has never been disproven.

Yes it has, at least as far as science is concerned, every model of the aether was shown to contradict experiment. Then Einstein developed Relativity and there was no need for an aether any more. I'm not going to go through all the evidence since there's at least 100 years worth of experiments including Michaelson-Morley.

>>7610476
Read these two wikipedia articles:
http://en.m.wikipedia.org/wiki/Aether_theories

https://en.m.wikipedia.org/wiki/Mechanical_explanations_of_gravitation

That will give you a general overview of different ether-based models. There are many more than what is mentioned.

Basically, it's the idea that some "substance" fills all space and the forces of nature (gravity, magnetism, etc) are results of pressure or flow or whirlpooling etc. of this substance.

The common view is that you don't need these models because general relativity explains it all. But even GR lacks explanations. For example, it says spacetime can bend, eg. empty space has properties. I'd argue these properties are intrinsic to the ether. Let the dick punching proceed.

Why is lowest energy a cop out?

Force is -dE/dx


On an interatomic potential , this leads to an oscillation about the minimum energy. Average bond distance is the lowest energy

>>7610490
Aether is rooted in occultism which is why people like this desperately want to shill it into modern theories. There is no reason to believe in aether any more than there is a reason to believe in gods or invisible unicorns moving particles around.

>>7610184
Since we can't see molecules and how they interact, we don't exactly have direct proof of anything in chemistry. All quantum theory is...well, theoretical. Molecular conformation is extremely dynamic, there is tautomerization, equilibrium, etc. A bond is not a fixed stable thing, there is rotation,etc. Pretty much incomprehensibly tiny things are flying around randomly at incomprehensible speeds and with incomprehensible complexity. So many early scientists have spent countless hours thinking about this stuff so why should we bother lel. I take this shit at face value and focus on bigger picture & practical stuff

Why doesn't the moon fall into the earth?

>>7610501
>we can't see molecules and how they interact

>>7610503
Exceedingly terrible analogy, I hope you don't actually believe that that's what is meant by electron "orbits".

Look up how to solve the harmonic oscillator and the hydrogen atom.

Literally all of your questions are that

>>7610503
>Muh semi-classical models

>>7610507
Its not a terrible analogy.

The moon doesn't decay into the earth because there and few effective ways for it to shed angular momentum and energy, making them effectively conservative.

Angular momentum and trivially energy, both commute with the Hamiltonian for which the electronic state is an eigenfunctions of, meaning they are also conserved in the electron.

Classical or quantum, it comes down to conservation laws

>>7610501
What about computational chemistry? It uses QM and produces testable results.

>>7610519
Most computational chemistry methods have gauge invariance properties and all of quantum mechanics can be formulated from a few different pictures.

It is an accurate computational tool. The "theory" part is still up in the air, since the results are equally well explained by dozens of different theories

>>7610547
>Most computational chemistry methods have gauge invariance properties

I don't understand what you're arguing here, all of physics is gauge invariant.

>and all of quantum mechanics can be formulated from a few different pictures.

But it would still be QM. The interpretation we use is pretty much irrelevant since we always arrive back at the same results (otherwise it would be trivial to rule them out and pick the "correct" interpretation).

> since the results are equally well explained by dozens of different theories

Such as? I'd be interesting in reading about this other theories that can rival QM in predictive power.

>>7610184
>I can't believe I haven't asked this question before, I feel like I've been fed shit for my whole life and I only realized it now.

He's beginning to learn...

>>7610585
Free your mind, Neo

>>7610490
But how would that be any different from the net effect the laws of physics have in regular modern physics space. You're just saying: Okay, there are laws at work, but I'm not content with accepting that they are the most basic laws. There has to be an ether, a substance that is more palatable to me, because I associate it with the idea of a medium, like air or water. How is this scientifically helpful? If it were a "moving/whirlpooling" substance, it would be working on the basis of some undiscovered set of parameters, but do you really think that we should make an analogy between the parameters that lie beyond our current laws of physics and the substance governing laws that are already quite well understood. It seems like a wrong analogy and it doesn't fit in the way things have progressed over time. Look at the way scientific paradigms have been opening up. They have been uncovering new laws of physics that seemed absurd compared tot the dogma at that time. Omni present ether would conceptually be a step back.

>>7610464
>hasn't heard of the Michelson-Morley negative result

>>7610514
The problem isn't whether you can get a stable orbit at some point, the real problem is why that accelerating charge doesn't radiate all its energy away and fall into the nucleus, at which point you need to go into quantum theory

>>7610368
>jiggly fluid
this. I'm in year one and this is the only way I can do it without my brain melting

>>7610184
Does your chemistry course not require you to take ANY quantum mechanics? Jesus Christ. It's impressive if you've managed to develop decent intuition for reaction mechanisms if you seemingly haven't done physical chemistry.

>>7610514
It's a terrible analogy because it leads poorly-educated chemists to believe that electrons literally orbit the nucleus like a satellite when really they they just sit inside a "fog" where the fog gets thicker the higher the probability of the electron being there.

The real answer for why electrons don't crash into the nucleus is because the limit of the integral of this "fog" function(multiplied by its complex conjugate) as the volume element tends to 0 around the origin (where the nucleus is) is 0 and so there is 0 probability of the electron being there.

>>7610485
>>7610487
>>7611527

Hey guys, I'm trying to find my cat that I think is black. I'm going to set up a very specific experiment that only detects black cats and completely ignores all other colors and variations.

Hmmm.... I didn't find my cat. Therefore, my cat doesn't exist nor do any other cats. No cats exist. QED.

>>7610804

A step backwards? That's like saying if fish discovered they live in water it would be a step backwards because their current theories don't require water.

I think the discovery of the ether could be the most important discovery ever. If it is flowing, we could pull energy from it at any point in space. We could bend/warp it to help our spacecraft travel faster. If it is like some assume to be the substance from which all matter is derived from, we could pull matter out of empty space.

In my opinion, general relativity is not incompatible with etheric theories. GR is probably just describing the properties of the ether in relation to mass - think gravity as "bending" of the ether, frame dragging around spinning massive objects, time dilation if the flow of ether controls the local "clock rate." Etc, etc. I think the evidence is already approaching overwhelming. But then again, I'm a scientific heretic who people punch in the dick.

>>7610184
bump for good thread

>>7612379
>Doesn't understand how important aether wind was to the aether hypothesis.

This is why I hate you faggots that constantly try and resurrect the aether, you don't have no idea what you're arguing for, so lets have a look at the history of the Aether hypothesis. When physicists turned their attention to the propagation of light they drew from all the other waves they had seen and assumed that light waves propagated through a medium, a reasonable enough assumption, since the physics of the day was Newtonian, and because c was known to be constant, the Aether was assumed to be stationary and there by give a unique reference frame. However it was known well before then that the aether couldn't be completely stationary, indeed it was Cauchy who suggested that perhaps the aether was "dragged" with the earth thereby explaining the previous experiments, but allowing the aether, by large, to remain stationary. However the physicists of the day also knew that the aether couldn't be completely dragged along with the earth, since it was incompatible with stellar aberration experiments. However the aether had to be dragged, this lead to a hypothesis of an almost stationary aether. However (yes, however again) any aether hypothesis had any dragging at all should mean that light would transform in a Galilean sense, but that wasn't borne out in the mathematics or the experiments. All of this lead to an incredibly bizzare (imo) idea of a special co-ordinate system that was "at relative rest" wrt the aether. As such it should be a simple to measure changes in the motion of light while moving in different directions. This lead to what's called "the first order experiments" you can find a list of them on wikipedia. These experiments lead to a series of inconclusive and contradictory results. Because of the failure of these experiments physicists needed to go to higher order, these were the "second order" experiments, and should have given positive results, they didn't.

>>7614519
Cont....

One of these experiments was the Michaelson-Morley experiment and it's null result should have been the final nail in the coffin for the stationary, nearly stationary and another form of aether hypothesis. However there was a slight shift in the interference fringes, not large enough to be aether wind. Lorentz used this to try and reformulate the aether hypothesis introducing length contraction. But by this point Einstein had published his paper on relativity and was able to re-derive length contraction without reference to some magical aether, moreover he was able to explain all the previous experimental results. As such aether hypothesis fell to Occam's razor.

>tl;dr aether hypothesis failed at every turn, every experiment that should have given a positive result returned inconclusive, contradictory or out right null results. Today we can, pretty conclusively, say that it doesn't exist. At this point we can also say that if it does it is completely undetectable and can therefore be assumed to not exist.

>>7610453
Where is the attraction in that plot coming from? Aren't both nuclei positively charged?

>>7610184

>>7612377
Do you mean the integral is 0 at the POINT origin, or is there like a tiny sphere around the origin where there's 0 probability of finding an election?

>>7612377
>There is zero probability of the electron being found inside the nucleus.

Top Kek.

>>7610184
>Also, where do electrons get the energy to keep moving?

Do you even physiks bro?

>>7612385
You don't seem to have much scientific knowledge anon.
You sound like a highschooler talking about the world while stoned, you're not making any real points.
And where is this evidence you're talking about, because so far you have made some assumptions but absolutely no points of evidence.

>>7616464
No, that's why he asked
Bump for kindling more discussion

Here's one:
>why do resonance structures work