Can Someone Tell Me Why I Should Believe Quantum Theory?

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Alright, I'm only a freshmen in college, so I don't fully understand all of the mathematics behind Quantum Theory, but I'm willing to listen if you think you can explain it to me and think it would be more useful for understanding certain aspects of the the Theory. However, the conceptual part I have heard many times with the extent of explanations I've heard adding up to "It doesn't make sense, but it's true". Why are most physicists so certain that Einstein was wrong about determinism and the perceived problems he saw believed arise from probabilities in physics? Am I just ignorant and stubborn for not being able to give up the idea of determinism, or is there really something extremely fundamental about that concept? Isn't it possible that the mathematics of quantum mechanics is just a statistical approximation of much more fundamental phenomenon? Please convince me that particles actually do have statical locations before we measure them, and tell me why it is so relatively uncontroversial of a fact among the scientific community. Your answers are much appreciated.

I will try to address your question.

If you have made it to quantum theory and you want someone to convince you to accept it as fact, you have missed a very important thing, which is, there are no facts in science. There are definitions, theories...some strong, some weak, postulates, and laws. Some of these seem more sound than others but it should be understood that they are all tentative and most models are only that, models. When a physicist publishes their work, they are saying "This is what I've observed, or derived, and here is one way to interpret it."

So you should not believe Quantum Theory as a fact. You should understand it as something that predicts and explains the behavior of the universe sufficiently well for our purposes in most situations.

Our current models of the universe and that within it were built by many contributors and generally do not hinge on one experiment or one derivation. Often times, the soundess of the model was arrived at by multiple people working from different angles, who ended up at the same spot. One experiment experiment in one field might have come to some conclusion A, while a different experiment in possibly another loosely related field might have concluded B, and a mathematician working on some abstract mathematical concept might have concluded D, and that D=A, and then realized that for D to be correct, B must be true, so B implies A.

I will give you a full explanation of quantum physics tomorrow evening when I have the time. In the meantime, if there are specific questions you have about the subject, ask.

There's a famous line that QM has never made an incorrect prediction.

Look at the transistors in your computer. That is sufficient reason.

ruveyn

Photo intensifiers wouldnt work if light energy were not in quanta (particle like packages).

And.. eyeglasses wouldnt work if light were not a wave phenomenon.

So we have technology that depends on light being waves, and technology that depends on light being particles.

Go figure.

"So you should not believe Quantum Theory as a fact. You should understand it as something that predicts and explains the behavior of the universe sufficiently well for our purposes in most situations."

Yes, this may be true, but often we can progress further when we can create models that explains the phenomenon but can be proven false. Scientists may strictly observe phenomenon at first, but their real motivation is usually to figure out what is actually going on and what those observations signify. From what I understand, most quantum interpretations seem to be the equivalent of, "I don't know where it will be, so it isn't anywhere until I look at it". ? How do you come up with such a wild Alice-In-Wonderland explanation for that? Another explanation that I can come up with off the top of my head: there are subtle forces we can't detect yet that effect the position of the subatomic particles, but since we can't detect those forces yet it seems random". What's wrong with that theory?

And to everybody else, yes I know a lot of technology that relies on quantum theory, and I'm not doubting if it works for the purposes of these devices (I'm pretty sure I'm typing this on a computer). What I'm really questioning is the interpretations of what's actually going on. Example: Fluid dynamics is useful in weather science, and weather science does a very good job of predicting what the weather will be the next day. However, they are only using approximations for a practical purpose, what is actually going is billions of atoms colliding into one another at different velocities, but being that specific isn't practical for predicting the weather, and the displacement of a few atoms probably won't change much. The weather scientist treats the weather like some kind of fluid for his job, even though that's not what it actually is, yet it still works.
Is it not possible that quantum theory is similar to this? It seems especially likely because of the whole probability thing, which to me screams approximation.

this, even plants would have a hard time without quantum effects,

they use quantum tunneling for photosynthesis if im not mistaken.

I have similar concerns about QM. I think that, like you, I don't deny that physical laws might change on a very small scale. However, I do find it intriguing that theorists can say something happens because of, or is influenced by ''randomness''.

Can it not be the case that we don't have a firm view of what exactly's going on? Would it not be more logical to say ''this seems to work on probability alone, but it might be because the math governing things so small is still not completely understood''?

In any case, I'll be looking forward to reading the answers you get in this thread.

Last edited by EBartleby on 19 Jan 2012, 1:13 pm, edited 1 time in total.

Thus far true. Quantum Physics is counter intuitive, but it has not been falsified empirically --- yet.

ruveyn

Well if youve gotta better idea..

But seriously Einstein said "God does not play dice with the Universe", so you're in good company if you have a gut revulsion to quantum theory, but its the only game in town.

Einstien owns the physics of big stuff like galaxies, and quantum theory rules the opposite realm of subatomic physics. Making the twain meet is the Holy Grail of physics today. Thats what all of the competing String theories are all about.

My own suspicion is that our concept of time is not sophisticated enough. The chance element in subatomic physics is indeed an illusion because we have this linear view of time. Time may have more dimensions and.. my brain snaps at this point. Ill get back to you later about it!

This is kind of what I saying, right? That to speak of chance is a result of a bad understanding rather than real chance. If we ever figure out how the underlying mechanisms work, even if that means radically changing our perception of things as fundamental as time and space, then wouldn't we be able to do away with the concept of ''chance'' entirely?

And nah, no better ideas I'm not doubting the work of men far more knowledgeable than I, it's just that I'd like to understand why their conclusions seem sketchy to me.

You shouldn't "believe" it. It's a scientific theory that has proved itself very effective and has not been falsified or superseded.

Should you have trouble understanding it? Yes.

Before you, you see 2 pills. Take the blue pill, and you'll wake up tomorrow same as before, and continue with life as usual. Take the red pill, and I'll tell you just how far down the rabbit hole goes.

Kudos if you can understand a reference that's already 12 years old.



Well, we can't go around saying things like "this chair is 67% there" and ending up being uncertain on whether you can sit there or not...

In all seriousness, the concept of a location in 3-D, physical space tallies with us only because it fits perfectly with the sensory data our brain receives. You can't pick up individual atomic particles, or light photons, so there is no sensory data per say with which to try and benchmark the same ideas of mass. While QM borrows from the methods of statistics, "statistics" in physics refers to distribution, not (directly) probability). Which is why an electron can be 5% there, given that we know it has x momentum.

(Thanks for the responses so far, they are quite interesting).

Well, what was said about our perception of time and space. Yes, it makes sense to me that even though we only perceive three spacial dimensions and experience time linearly, it is quite possible that there are different dimensions that would be naturally difficult to process conceptually, and thus the only sensible way to navigate through this strange side of the universe would be with mathematics. However, no matter how complicated, convoluted, or dynamic all these extra dimensions get, I can conceive of them as possible; difficult to clearly think about, much less work with, but possible. On the other hand, I cannot conceive of anything that isn't deterministic. Even if there are distortions in time, those distortions are caused by something else. Also, the past is permanent, it is absolutely certain where the electron WAS during the experiment, so I can't think of why the future would be any less certain from the perspective of the universe. Sure, we have limited ability to predict the future, but that's because we experience time linearly.

On an unrelated note, here's a though experiment I whipped up in hopes to demonstrate my point: Let's say that you have an experiment where a scientist receives the results of a device recording the position of an electron. The results are recorded by a computer and signaled in an automated voice through radio waves. However, the scientist is actually one light minute away. When does the particle go from being distributed to being in one location? When the scientist actually receives the information, or when the computer records it? Also, what if the scientist isn't there to receive the information, does the electron stay distributed?

As far as I know, neither. The concept of the experimenter's perception of the particle's location, and the actual location of the particle, are 2 different things. By and large, they are exactly the same. But because most of the things that QM deals with are empirically unverifiable by current technology, we can never be completely certain.

A very simplistic parallel is this: if you ask somebody where Jane is, he can say: "she's at school", or "at Starbucks". Jane's exact geographic coordinates are not the same information as "at school", and unless she has a GPS tracker, you are unable to ascertain that Jane is indeed at coordinates (x, y, z). So you have an integral (roughly, the volume occupied by the school), which, if you think about closely, are quite similar to the uncertainties that QM has about mass. Obviously Jane cannot be everywhere in school at once, and, given that she's moving around, you cannot know for sure that she is in that exact same spot as she was before. Thus we have the analogous concept of the distribution of the location of where the particle is likely to be.

So Jane did not "go from being distributed to being in one location" contingent upon your receiving of the information that she is "at school" (or otherwise). Jane is where Jane is; what you know of her whereabouts is entirely another matter.