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Author Topic: Is it possible to suspend an electron in an EM field?  (Read 11244 times)

Offline Evinagro

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Exactly as the title suggests, I am wondering whether an electron can be suspended in an electromagnetic field in a vacuum without protons or neutrons nearby.


 

Offline PmbPhy

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Re: Is it possible to suspend an electron in an EM field?
« Reply #1 on: 01/02/2015 00:32:03 »
Only if you place it in a uniform electric field. However you have to have charges to generate that field. However since the field is uniform those charges can be a large distance away.

Question: What does "nearby" mean in this context? Angstroms? Millimeters? Kilometers?
 

Offline Evinagro

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Re: Is it possible to suspend an electron in an EM field?
« Reply #2 on: 01/02/2015 00:48:21 »
Only if you place it in a uniform electric field. However you have to have charges to generate that field. However since the field is uniform those charges can be a large distance away.

Question: What does "nearby" mean in this context? Angstroms? Millimeters? Kilometers?

Allow me to reword that, a controlled environment where the electrons are suspended within a vacuum
 

Offline chiralSPO

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Re: Is it possible to suspend an electron in an EM field?
« Reply #3 on: 01/02/2015 03:31:18 »
Do cathode rays or electrons in particle accelerators count?
 

Offline evan_au

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Re: Is it possible to suspend an electron in an EM field?
« Reply #4 on: 01/02/2015 06:18:42 »
This problem has been faced by researchers trying to build quantum computers - they want some stable particle state that is isolated from the external environment, and yet controllable so it can take on a quantum superposition.

Electrons are one of the potential methods to store Quantum Bits (qubits).

As well as storing electrons in a vacuum using electric & magnetic fields, it is possible to store information on unpaired electrons in a crystal lattice.
 

Offline PmbPhy

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Re: Is it possible to suspend an electron in an EM field?
« Reply #5 on: 01/02/2015 07:55:44 »
Only if you place it in a uniform electric field. However you have to have charges to generate that field. However since the field is uniform those charges can be a large distance away.

Question: What does "nearby" mean in this context? Angstroms? Millimeters? Kilometers?

Allow me to reword that, a controlled environment where the electrons are suspended within a vacuum
If you place an electron in a uniform electric field which is directed in the same direction as the Earth's gravitational field and adjust the field so that the forces balance then the electron will be suspended. This was something Millikan used in the Millikan's Oil Drop Experiment.
 

Offline jccc

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Re: Is it possible to suspend an electron in an EM field?
« Reply #6 on: 01/02/2015 09:21:23 »
In electron's eye, everywhere is vacuum.

Electrons can never touch each other by nature - they repel each other.

Electron will follow force and move like anything else. But electron is chicken, dare to get too close to proton.

If suspend an electron in an EM field is impossible, quantum physicists will go nuts.

 

Offline PmbPhy

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Re: Is it possible to suspend an electron in an EM field?
« Reply #7 on: 01/02/2015 11:42:25 »
Quote from: jccc
If suspend an electron in an EM field is impossible, quantum physicists will go nuts.
Why on earth do you say such misleading things like this?

The only way your comment makes sense is to let the OP know that his question only makes sense classically (which appears to be what he wanted). Quantum mechanically it makes no sense for an electron to be at rest. If that's what you meant then you need to be specific and explain. Merely making statements like that and not explaining helps nobody, i.e. it's very bad science!
 

Offline UltimateTheory

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Re: Is it possible to suspend an electron in an EM field?
« Reply #8 on: 01/02/2015 14:17:37 »
Exactly as the title suggests, I am wondering whether an electron can be suspended in an electromagnetic field in a vacuum without protons or neutrons nearby.

Particles can be held in magnetic traps.
Antiprotons and positrons especially require it.

http://en.wikipedia.org/wiki/Magnetic_trap_%28atoms%29

http://en.wikipedia.org/wiki/Penning_trap
 

Offline PmbPhy

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Re: Is it possible to suspend an electron in an EM field?
« Reply #9 on: 01/02/2015 14:46:23 »
Quote from: UltimateTheory
Particles can be held in magnetic traps.
Antiprotons and positrons especially require it.

http://en.wikipedia.org/wiki/Magnetic_trap_%28atoms%29
The OP's question regarded electrons. The magnetic trap only contains neutral particles which have magnetic moments (thus electons are out). That link says
Quote
A magnetic trap is an apparatus which uses a magnetic field gradient to trap neutral particles with magnetic moments.

As far as Penning traps go this page - http://en.wikipedia.org/wiki/Penning_trap - seems to imply that the particles are not at rest and therefore it cannot suspend charged particles.

Earnshaw's theorem states that neither an electric nor a magnetic field can be used to hold a single charge or system of charges at rest - http://en.wikipedia.org/wiki/Earnshaw's_theorem

Even my example cannot be used to hold a charged particle in stable equilibrium. If the field is off even by an infinitesimal amount then it will accelerate. If its close enough then it can be slowed to a crawl.
« Last Edit: 01/02/2015 22:44:56 by PmbPhy »
 

Offline syhprum

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Re: Is it possible to suspend an electron in an EM field?
« Reply #10 on: 01/02/2015 16:04:07 »
To hold a body stationary one has to observe where it is and by means of a servo system to apply forces to it in the opposite direction to those that are tending to move it this is what is done with magnetic bearings, maglev trains etc.
Millikan was able to observe his oil drop visually as its mass was vastly greater than the force exerted by the EM field of one electron so that it only drifted slowly.
To stabilise the position of one isolated electron even if its position could be observed which is probably not possible would require a servo system of un realisable speed.   
« Last Edit: 01/02/2015 16:06:14 by syhprum »
 

Offline jccc

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Re: Is it possible to suspend an electron in an EM field?
« Reply #11 on: 01/02/2015 16:14:00 »
Electrons are suspended in EM field all the time, otherwise no atoms able to form.

Question is, with 10^40 g attraction between electron and proton, what force suspends electron over proton?

Anyone can explain it without using magic?

 

Offline PmbPhy

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Re: Is it possible to suspend an electron in an EM field?
« Reply #12 on: 01/02/2015 16:22:31 »
Quote from: jccc
Electrons are suspended in EM field all the time, otherwise no atoms able to form.
You're once again ignoring quantum effects.

Quote from: jccc
Anyone can explain it without using magic?
Why on Earth do you keep acting like this when your error has been pointed out to you countless times? You're a macroscopic being who was raised in a macroscopic world. All of your senses are macroscopic and can only report macroscopic information to you. Therefore the real nature of reality was never available to you and never will be. You have to rely on instruments and careful thought, reasoning and analysis which is the result of the work of countless scientists over many many years. Why are you unable to grasp the fact that nature as it really is, is unavailable directly to all of your senses. Therefore you cannot expect it to make direct sense when you compare it with what your senses tell you. Why is that so hard for you to understand? We've told you where you can learn more about it and yet you refuse. So stop making this silly comments about magic. It's you who isn't willing to do the work to understand it. You can't blame anybody else for that. And we've always explained it without magic. It's just that you don't understand it and you call anything you can't grasp "magic". Come out of the cave please!
« Last Edit: 01/02/2015 16:39:36 by PmbPhy »
 

Offline syhprum

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Re: Is it possible to suspend an electron in an EM field?
« Reply #13 on: 01/02/2015 21:12:25 »
PmbPhy , a double negative has snuk in in your description of Earnshaws theory
 

Offline PmbPhy

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Re: Is it possible to suspend an electron in an EM field?
« Reply #14 on: 01/02/2015 22:45:54 »
PmbPhy , a double negative has snuk in in your description of Earnshaws theory
That's what happens when you rewrite a sentence and aren't careful about it. :)

I fixed it so that it's okay now. Thanks.
 

Offline jccc

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Re: Is it possible to suspend an electron in an EM field?
« Reply #15 on: 01/02/2015 23:54:43 »
Pete,

I still have no clue. No matter who's theory, got to be logical to the mind.

Atoms made matter. How atom formed? What's in an atom?

Let's see hydrogen atom, 1 electron and 1 proton, they attract each other.

Then what? How it works? The electron is suspended by what? 
 

Offline jccc

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Re: Is it possible to suspend an electron in an EM field?
« Reply #16 on: 02/02/2015 01:45:14 »
In electron's eye, everywhere is vacuum.

Electrons can never touch each other by nature - they repel each other.

Electron will follow force and move like anything else. But electron is chicken, dare to get too close to proton.

If suspend an electron in an EM field is impossible, quantum physicists will go nuts.

Just maybe, they are nuts.
 

Offline PmbPhy

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Re: Is it possible to suspend an electron in an EM field?
« Reply #17 on: 02/02/2015 09:52:15 »
Pete,

I still have no clue. No matter who's theory, got to be logical to the mind.

Atoms made matter. How atom formed? What's in an atom?

Let's see hydrogen atom, 1 electron and 1 proton, they attract each other.

Then what? How it works? The electron is suspended by what?
Please answer my question for just this one time!! Why do you insist on asking questions when you know that the answer will require a lot of work to learn? You know darn well that such questions simply cannot be answered in a single post. It takes a lot of work to answer these questions. What can be explained I've already explained. You simply don't have a strong enough understanding of science to understand what you've been told to date. And that's all your fault because you simply refuse to do the work required to learn it, i.e. reading! The only thing that makes sense is that you're too lazy and you want us to spoon feed you an entire course on quantum mechanics. Forget it. That will never happen.
« Last Edit: 02/02/2015 11:46:30 by PmbPhy »
 

Offline PmbPhy

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Re: Is it possible to suspend an electron in an EM field?
« Reply #18 on: 02/02/2015 11:15:04 »
Quote from: jccc
I still have no clue. No matter who's theory, got to be logical to the mind.
Would you like to know when it all started making sense to me? It was when I was talking to my physics advisor when I was studying quantum mechanics as an undergraduate. I said that I can't understand it and he told me that the best way to think about quantum mechanics was to keep this rule in mind - Shut up and calculate!

Do you know what that means? It reminds us that laws of physics have one function. They are used to help us describe nature and make predictions when we execute a given experiment. That's all that they're supposed to do. They have no reason to be logical whatsoever because our senses weren't developed to have a logical understanding of nature at the quantum level.

Got it? You see, you keep insisting that quantum mechanics should be able to answer "Why" questions when in fact no theory is supposed to do that. All a theory is supposed to do is describe nature and let us make predictions on what to expect in a given situation, i.e. when we run an experiment. So we can't use quantum mechanics to ask why an electron doesn't fall into the nucleus of an atom. All we can ask is whether it does and where to find electrons around the atom. And that it does very well. At least with hydrogen.
« Last Edit: 02/02/2015 11:18:03 by PmbPhy »
 

Offline jccc

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Re: Is it possible to suspend an electron in an EM field?
« Reply #19 on: 02/02/2015 11:48:29 »
What is an Atom?

The atom was once thought to be the basic building block from which all else was created. It is the smallest particle of an element that still has the characteristics of that element. Helium atoms, for example, are used to fill balloons because they are lighter than air. One helium atom will rise up through the air, but because it is so tiny, many are needed to conquer the Earth's gravity. Today, physicists know that atoms are made from even smaller parts called elementary particles.

Atomic Structure

The nucleus, at the centre of an atom, is made up of elementary particles called protons and neutrons. Travelling around the nucleus, in a variety of ways, are electrons. An Electron Orbital Path is the space through which electrons travel as they tour the nucleus. Each Electron Orbital Path has a limit to the number of electrons allowed on it. Figure 3.1 shows blurry electrons because both their position and precise momentum can never be known at the same time (this is the Heisenberg Uncertainty Principle). These paths are known as shells.

The shell an electron follows depends on its energy. All the electrons in a specific shell have exactly the same amount of energy. To move from one shell to another, an electron must either gain or release a fixed amount of energy. A fancy way to say this is: electrons are restricted to quantized orbits. These shells are not necessarily fixed in size, but defined in terms of probability. Although there is a chance that an electron could be thousands of kilometres away, it is more likely to be close to the nucleus around which it travels.

Although useful to picture electrons orbiting a nucleus as planets encircle the Sun, it is not entirely accurate.

The next section illustrates these concepts with a race analogy.

Electron Orbital Race

Imagine a race with the following rules:

runners on their track must run single file, without passing;
runners must remain on their track while they have the same physical fitness;
a runner that gets a boost of energy must jump to an outer track;
a runner that loses energy must jump to an inner track; and
there are many tracks, shown simplified in Figure 3.2.
Atom Analogy

Figure 3.2. Atom Analogy.

In this analogy, a runner gains energy by eating fruit. When this happens, the runner instantly obtains a new level of fitness, and must jump to a new track according to the rules. Runners can never be moderately fit, or somewhat lazy, but always lose or gain specific amounts (discrete units) of fitness.

Quantum Leap

The word quanta means discrete units. It is analagous to the difference between a ladder and a slide; you can stand anywhere on a slide, but only on the rungs of a ladder. Now substitute the words track and runner with shell and electron. The word quantized describes the small, discrete, leaps that electrons make from shell to shell, as though ascending or descending a ladder.

The act of an electron jumping between two shells is called a quantum leap.

Force Carrier

Electrons do not eat apples to make a quantum leap (their mouths are too small). They do, however, revolve around the nucleus as close as possible because it uses less energy; this is known as their ground state. If an electron gets extra energy, it must leap to a higher shell. After a short period of time, it will spontaneously release the extra energy, and leap back to its former shell. Just as a runner eats fruit for more energy, electrons get energy from a force carrier to make quantum leaps.

Pete,

I can't even accept the above statement, can you? Worse than Bible story to me.
 

Offline PmbPhy

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Re: Is it possible to suspend an electron in an EM field?
« Reply #20 on: 02/02/2015 11:52:17 »
Quote from: jccc
I can't even accept the above statement, can you? Worse than Bible story to me.
That's because to refuse to learn physics and quantum mechanics. Until you do nothing will change.

Where did you copy that from anyway?

By the way, I sincerely hope that you're not getting the idea that I'm trying to be a jerk to you or am intentionally being mean, because that's not my desire. Worst case I'm explaining the areas of your ignorance (where the term 'ignorance' means 'lack of knowledge' and stupid)
« Last Edit: 02/02/2015 12:12:05 by PmbPhy »
 

Offline jccc

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Re: Is it possible to suspend an electron in an EM field?
« Reply #21 on: 02/02/2015 14:26:14 »
Pete, that's from how stuff works.

You are my teacher and best friend here, always will be.
 

Offline PmbPhy

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Re: Is it possible to suspend an electron in an EM field?
« Reply #22 on: 02/02/2015 14:39:19 »
Pete, that's from how stuff works.

You are my teacher and best friend here, always will be.
Thanks. Then explain to me why you won't answer questions I directly ask of you?
 

Offline jccc

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Re: Is it possible to suspend an electron in an EM field?
« Reply #23 on: 03/02/2015 08:59:55 »
Pete, that's from how stuff works.

You are my teacher and best friend here, always will be.
Thanks. Then explain to me why you won't answer questions I directly ask of you?

Pete,

I'm such an attention seeker, if I have the answer, I'll answer before you even ask.
 

Offline PmbPhy

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Re: Is it possible to suspend an electron in an EM field?
« Reply #24 on: 04/02/2015 03:32:46 »
Quote from: jccc
Pete,

I'm such an attention seeker, if I have the answer, I'll answer before you even ask.
That's not true. The questions I'm referring to that you refuse to answer are not questions about your knowledge or which require you to solve a problem. I'm asking about your motivations and reasons why you refuse to answer certain very simple questions. For example; countless times I've suggested that you pick up a book on quantum mechanics and read it. It's quite obvious that you've never done so. I've made the same suggestion about articles on my website about the philosophy of physics and you ignore most of them. So I ask once again, Why?

Best wishes,
Pete
 

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Re: Is it possible to suspend an electron in an EM field?
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