A electron can exist in everywhere ?

G-sound

When it acts as if it's in all possible states at once in the universe, and some pretty complicated machinary depends on this wave nature of electrons, what does it say about the world?

G-sound

I'd say you are right that it exists though I am far less certain how and when it does.

Drakkith

That the particle obeys the mathematical laws developed by QM. That's it.


Please, leave ramblings on reality out of this thread. They don't pertain to the thread at all and only serve to confuse people.

Amok

It never acts (it is never seen, or measured to be) as if it were in many different states at once. That's one of the founding concepts of quantum mechanics. Whether the particle actually is in superposition of states when it is not observed is a question of philosophy. I still don't see how this has anything to do with the reality of our world, because that electron is still real, whether it is in a superposition of states or not.

G-sound

No, all physical laws should describe the world we observe. If they describe differently, then either the laws are wrong or the world we observe isn't quite the idea we have of it.

G-sound

Is a bacteria in superposition real? What about something even bigger? By 'real' do you mean just what is observed or do you also include things that are not? If the former, why did you even try to muddle the question i asked?

Amok

And they do, quantum mechanics is a theory about what we observe, exclusively about that actually. No can observe electrons in a superposition of states, for example, and qm doesn't say you can.

Bacteria aren't really described by quantum physics, as far as I know. I'm not saying that only things that we observe are real, and that things in superpositions aren't real. An electron is real whether it is in a superposition of states or not. Is the superposition itself ever real? No clue, no one knows.

G-sound

As i said earlier, the wave nature of electrons is widely utilized these days. If it were just a mathematical trick, qm would reduce to classical mechanics. I think you might be confused that classical objects and quantum ones are similar.

PP. I'd say that people trying to prove objective reality solely on qm have already lost the battle.

Drakkith

I think you should look and see what superposition really is. No one here is saying that the wave nature of electrons doesn't exist or is a trick.

How so?

G-sound

Tell me.



Tell me what it is you are saying, not what you are not saying. You've beeen saying that reality is real because we obviously observe it(great argument) and because when you detect it, you've found it to exist(how surprizing). If the wave nature of electrons is real and exists as you suggest, electrons are not localized in spacetime and this violates known laws and principles of classical physics(as well as the notion of objective reality)



First look up the commonly established criteria for objective reality and compare them with qm. You might want to read a bit on qm before you start with the criteria though.

Drakkith

There are plenty of references online that a quick google search will provide. Have you read any of those? Have you read more than one source? If so, what questions do you have about it?

No, nothing about measuring the electron has been construed into being something about reality. Reality is, arguable, ill defined and not appropriate for discussion as such. What we HAVE been saying is that the wavefunction PREDICTS WHERE THE PARTICLE WILL BE. That's it. You've misconstrued that into saying "particles don't behave like waves". This is not true, as we've explained more than once.

They appear in one place, and ONLY one place whenever we interact with and detect them. QM says nothing about them "spreading out" over space. That is only the wavefunction, where they may appear next. As I've said already we have NO interpretation of what the wave function is, other than a mathematical tool, that is widely accepted as the "best" interpretation. As far as I know at least.

I'm not going to play this game. Either explain what you mean, or don't bother posting it.

G-sound

You said i had to learn more about superposition, now you are asking what i want to know about it?




No, you are wrong. The wave nature is not just a mathematical trick for predicting where a particle might be. It's an aspect of what a particle is and a particle is actually both a wave and a particle. Diodes, transistors, electron microscopes... all use the wave aspect of electrons, so saying that its wave nature is just a calculational trick is just plain wrong.




I've said no such thing.



Look up Heisenberg's uncertainty principle, also the spreading out is part of nature and the basis of modern electronics. Furthermore, look for "devices that use qunatum mechanics" on google to get a better idea how much of a role the wave nature of particle plays these days.



I'd use the reality criterion that Einstein, Podolsky and Rosen chose for their attempt to prove qm was incomplete, that later turned against them with Bell/Aspect. It was a case of reductio ad absurdum on their side that to their dismay turned true.

Whether the wavefunction is real or not doesn't change the core of the argument - we have an excellent theory with verified predictions but the predictions go against common sense and preconceived notions that most people consider obvious and true - like chairs, tables, cats and moons...

Drakkith

I give up. If you are going to take everything out of context, not listen, not put the effort into learning, and accuse us of saying things we haven't then I will have no more of this thread.


A perfect example of what I just said.

Amok

I feel like he's trolling us. Repeating stuff he read somewhere else without understanding it.

ZapperZ

This is highly incorrect.

Note that we observe and measure the consequences of superposition. The existence of bonding-antibonding in chemistry is one clear example! Furthermore, I've mentioned the Delft/Stony Brook SQUID experiments in this forum a gazillion times already. I'd like someone to tell me that the presence of the coherence gap that they measure is NOT due to such superposition. Or better yet, write a rebuttal to those two papers, if you will!

People seem to forget that when you make a measurement, what you have "collapsed" is only the information related to THAT OBSERVABLE! If another observable is non-commuting, you've done nothing to destroy the superposition of that observable! And this is what we can take advantage of in trying to detect such superposition, and this is what has been done in the numerous Schrodinger Cat-type experiments. Anyone can do a search on the 'net on these types of experiments before making such silly claim that we don't know if such superposition is real or not!

Zz.

Amok

How so?

I'd never heard about that, but I'll check it out.


Sure, but you haven't observed it either.


I'm sorry, no need to get all up in arms about it. I was taking an unassuming position to respond to a guy who was obviously rambling because wether or not superposition is real it has nothing to do with the existence of reality.

ZapperZ

Now that we've established that we DO have such superposition in QM, and that it IS "real", let's tackle this annoying question brought up by the OP, who, BTW, never re-entered this thread after posting such a thing.

If an electron can exist everywhere simultaneously, then no particle accelerator in the universe can work, and neither can your electronics!

{Shock and confusion rings through the thread!!}

"But ZapperZ! You just said that superposition is real, and so, doesn't this imply that you've just agreed that an electron can exist everywhere at the same time?"

And I will argue that in many instances, the electron can be describe as a classical particle and can easily be detected to be as that!

So what's the difference? One has to look at the scenario!

If I have a linear accelerator, let's say, and I created an electron at the gun at a certain time, I darn well have an electron that is NOT everywhere within the accelerator beamline! Why? Because I know well-enough when it is created and where! The very fact that I can detect it LATER down the beamline is the evidence. If it is everywhere all at once, I would detect it immediately at the end of the beamline. But I don't! So the insistence of an electron can exist everywhere is easily falsified by such an observation.

But why is this different than in the QM case?

If I have some way of generating an electron inside this beamline such that I have NO IDEA WHERE it will pop up at any given time (i.e. the only thing I know is that the probability of it appearing inside the walls of the beamline is zero), then NOW, I have a different situation/scenario than before. Now, the fact that I don't know when and where that electron will appear has changed the game entirely! The electron that appears in such a scenario can now be compared to, say, your infinite square well case in QM. You now have a QM case!

One cannot simply grab a QM principle, and then blindly apply it to every single scenario no matter how absurd it is. Leave such dubious practice to cranks who only learn about QM from pop-science sources.

Zz.