Indisputable Proof that Electrons Exist?

In summary, my friend and I came to wondering if there is indisputable proof that electrons exist? Sure, I can sit in a physics class and talk about their speed, mass, spin, etc... but how do I know that all that is real? How do we know that there isn't something else in their place that functions similarly and therefore gives us the results we expect, but at the same time explains some of the problem areas of physics?We can see electrons with the five senses, feel them, and interact with them. We also have a model for how they operate around the nucleus. However, we don't have a definitive picture of what they look like.
  • #1
Weather Freak
40
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My friend and I came to wondering if there is indisputable proof that electrons exist? Sure, I can sit in a physics class and talk about their speed, mass, spin, etc... but how do I know that all that is real? How do we know that there isn't something else in their place that functions similarly and therefore gives us the results we expect, but at the same time explains some of the problem areas of physics?

I am under the impression that no one has ever seen an electron or any other, smaller particle. If this is the case, isn't there the possibility that we're a little off base?
 
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  • #2
Chemistry is founded on "an entity" that has negative charge so atoms can bond, an essentially, so everything in the universe can work.

An electron is a lepton, showing that it is the one of the smallest units of recognizeable matter ever quantized

No one has really "seen" an electron. But you don't need too. We see its crucial usage in computers/electronics, chemical bonding, and creating photons.

Humans have classified this little thing as "electron," regardless of whatever it is called or looks like, we know it exists (mainly through chemistry).
 
  • #3
This may be cliché but what ever;

Can you see the wind?
 
  • #4
Weather Freak said:
How do we know that there isn't something else in their place that functions similarly and therefore gives us the results we expect, but at the same time explains some of the problem areas of physics?
Whatever this "something else" is that has all the properties of the electron - that's the thing we call an electron.

Single electron spins have been measured:
http://domino.watson.ibm.com/comm/pr.nsf/pages/news.20040714_nanoscale.html

Single electron transistors have been around for a while:
http://physicsweb.org/articles/world/11/9/7/1

Single electronic orbitals in a molecule were recently imaged by high speed lasers:
http://www.nature.com/physics/highlights/7020-3.html

Last year, a single electron trapped in a quantum dot was detected:
http://adsabs.harvard.edu/abs/2005AIPC..772..775S
http://adsabs.harvard.edu/abs/2005cond.mat.10269G
 
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  • #5
I think I get it... basically we have no idea what it actually looks like and the pictures in all the books are simply our best guess? And the concept of an electron is a subatomic particle which has all the properties that we attribute to an "electron"?
 
  • #6
Weather Freak said:
I think I get it... basically we have no idea what it actually looks like
There is no such thing as "what it looks like". It is smaller than the sense we use to see things.

So, the manner in which it interacts with the world around it is what defines its identity - and "what it looks like" is both irrelevant and non-existent.

[EDIT] I like Gokul's definition: Whatever this "something else" is that has all the properties of the electron - that's the thing we call an electron.
 
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  • #7
I see, so it's not a sphere at all, but rather the sphere is just how it is represented in the textbooks...?
 
  • #8
How have you proof that birds exist, and are not a figment of your imagination?
 
  • #9
Weather Freak said:
I see, so it's not a sphere at all, but rather the sphere is just how it is represented in the textbooks...?

I don't think it's a sphere, either. It is a point-particle with no internal constituents (as of today!).
 
  • #10
arildno said:
How have you proof that birds exist, and are not a figment of your imagination?

Well we can feel birds, we can hear birds, we can see birds, we can interact with birds.

When I touch a bird I know that I am touching it because I can see myself place my hand on it.

It's tough to have this kind of confidence when none of the major senses can actively detect an electron.

Now I'm not saying that I don't believe they exist - I understand how they apply to physics and how they can be detected and manipulated in experiments, but it just isn't the same gut feeling that I get when I see a bird and know that it is, indeed, a reality.
 
  • #11
electrons

Some people, like instrumentalists (who are critiqued in David Deutsch's 'Fabric of Reality') view unseen & unpicturable entities like electrons as ideas that allow us to predict phenomena.

Others see them as actual entities. This view poses no problems if we abandon the idea that what is real must be picturable.

Lren
 
  • #12
Weather Freak said:
Now I'm not saying that I don't believe they exist - I understand how they apply to physics and how they can be detected and manipulated in experiments, but it just isn't the same gut feeling that I get when I see a bird and know that it is, indeed, a reality.
This is a general problem science is having (and, frankly, has always had). As it introduces new concepts about how universe works, it creates models that have no precedent in our day-to-day lives.

A related example is the orbit of the electron around the nucleus. Laypeople had no precedent for orbitals and probability clouds. A lousy analogy is that of planets orbiting a star, but that breaks down very quickly.

So, the upshot to all this is that, whenever we are exploring new territory in science, we by definition are exploring things that our everyday experiences have never encountered, and that our biological senses are unable to grasp. We must abstract our understanding of the world around us by way of mathematical models and artificially-enhanced senses.
 
  • #13
Weather Freak said:
Well we can feel birds, we can hear birds, we can see birds, we can interact with birds.
Well we can feel electrons (1), we can hear electrons (2), we can see electrons (3), we can interact with electrons (4).

1. static discharge, gold leaf electroscope, van de graaff demos
2. plasmon-phonon coupled modes
3. heck, most any time we see anything we're seeing the electrons, but in addition consider experiments linked in earlier post
4. all of the above are interactions, but also, ask anyone that's been electrocuted

How do you know Pluto (the dwarf planet) exists? You can see it (not with the naked eye), but can you hear it, feel it or otherwise interact with it?
 
  • #14
Believe it or not!

The act of believing (or deciding not to) is proof that electrons exist. Without electrons you wouldn't believe (or not believe) anything because your neurons would be dead-wood in your skull. None of the electron activity which is evoked by the actions of the sodium/potassium pump (an attribute of the physiology of neurons) would take place. Praised be the almighty electron!
 
  • #15
Weather Freak said:
I think I get it... basically we have no idea what it actually looks like and the pictures in all the books are simply our best guess? And the concept of an electron is a subatomic particle which has all the properties that we attribute to an "electron"?
Yeah. Its essentially a defnition.
 
  • #16
Weather Freak said:
Well we can feel birds, we can hear birds, we can see birds, we can interact with birds.

When I touch a bird I know that I am touching it because I can see myself place my hand on it.

It's tough to have this kind of confidence when none of the major senses can actively detect an electron.
Stick your finger in a light socket and then try that statement again...

[Note: do not stick your finger in a light socket]
Now I'm not saying that I don't believe they exist - I understand how they apply to physics and how they can be detected and manipulated in experiments, but it just isn't the same gut feeling that I get when I see a bird and know that it is, indeed, a reality.
Well, then you'll have a real big problem with a very high fraction of what is known in science. Very, very little can be directly detected and virtually nothing can be quantified by our senses.
 
  • #17
nannoh said:
Believe it or not!

The act of believing (or deciding not to) is proof that electrons exist. Without electrons you wouldn't believe (or not believe) anything because your neurons would be dead-wood in your skull. None of the electron activity which is evoked by the actions of the sodium/potassium pump (an attribute of the physiology of neurons) would take place. Praised be the almighty electron!

Yes, but that's still inference of their existence. It's still a model.
 
  • #18
russ_watters said:
Stick your finger in a light socket and then try that statement again...

The OP is not saying you don't get a shock. The OP is merely saying we don't have direct evidence of what is doing the shocking. It's all inference, all models.
 
  • #19
DaveC426913 said:
Yes, but that's still inference of their existence. It's still a model.

Philosophically everything is a model. Our senses interpret all phenomenon in terms of models. We have constructed a model of the universe with our senses and our capacity to recall past experiences.

Perception is a result of how our senses interpret every phenomenon. Phenomena are represented by our interpretation of what our senses can gather about them. How much more fundamental can you get than our perception and how it works? It works because of electrons.

A cheese burger is a model. You can taste it, touch it, derive energy from it and enjoy it. Just as you can feel the heat, see the light etc of a light bulb that is only a light bulb because of electrons.

The cheese burger is only a cheese burger because of a herd of cattle in Brazil, a field of lettuce in Mexico and dairy cows in Idaho or oil refineries in New Orleans (for real or fake cheese). You don't see these elements and you probably will never see them all at the same time. You will only see a model example of them - the "cheese burger".

The majority of us don't see the process that goes into producing cattle, lettuce or cheese. The majority don't see the chlorophyll present in the lettuce. 99% of peopele are unaware that it is responsible for the absorption of light to provide energy for photosynthesis. The majority of us don't see the chlorophyll molecule that contains a magnesium atom held in a porphyrin ring. A large number of us can't even pronounce "chlorophyll". But we eat it. And that is our model of that particular phenomenon. Its a leafy thing that goes well in a cheese burger. Everything's a model of the next level of process.

At what level of process are electrons situated?
 
  • #20
DaveC426913 said:
The OP is not saying you don't get a shock. The OP is merely saying we don't have direct evidence of what is doing the shocking. It's all inference, all models.
But that was the point people were making previously about definitions. You know "something" is causing the shock. That "something" is electrons, by defnition. Even if virtually everything we know about electrons is wrong, we still know they exist in this specific context.
 
  • #21
Gokul43201 said:
Well we can feel electrons (1), we can hear electrons (2), we can see electrons (3), we can interact with electrons (4).

1. static discharge, gold leaf electroscope, van de graaff demos
2. plasmon-phonon coupled modes
3. heck, most any time we see anything we're seeing the electrons, but in addition consider experiments linked in earlier post
4. all of the above are interactions, but also, ask anyone that's been electrocuted

How do you know Pluto (the dwarf planet) exists? You can see it (not with the naked eye), but can you hear it, feel it or otherwise interact with it?

Sure, we can "see" them and "interact" with them in these ways, but it's more of an interaction with a collection of them...

For instance, if I place my hands on a Van de Graff, I can feel and see the consequence of electrons, but I don't actually see the individual electrons. I don't see one electron after another moving around.

I can use Newton's equations to talk about how a ball flies through the air and I can accept what they say on a gut level because I can then take a ball, toss it through the air, and watch as my calculations become a reality.

Now, I may be able to figure out, on paper, what an electron will do if I take it and exert a force on it... and I may be able to confirm that through an experiment, but it's not the same. The experiment would not let me see the individual electron do what I calculated it would do. Instead, the experiment would measure the motion in an indirect way.

Scientifically I can say that it checks out, and I know that even though the measurements were obtained indirectly, they are still valid. However, there is still that gut feeling that isn't present because I can't interact with the electron like I could with the ball.

Perhaps another example would be to take a ball and do different things to it. I can throw it upwards and see what happens. I can throw it against my car and see what happens. I can bounce it on the ground and see what happens. Once I do this enough (and who hasn't?) I develop a sort of instinct for how it should work. I can picture it working in my mind because I have seen it work. I have interacted with it.

It's not that easy to do with an electron, is what I'm saying. It takes more than just analyzing pages of equations to develop an instinct of what how an electron works.
 
  • #22
Weather Freak said:
Sure, we can "see" them and "interact" with them in these ways, but it's more of an interaction with a collection of them...

For instance, if I place my hands on a Van de Graff, I can feel and see the consequence of electrons, but I don't actually see the individual electrons. I don't see one electron after another moving around.
Why does that matter? You don't need to be able to see individual water molecules to know water exists.
 
  • #23
nannoh said:
Philosophically everything is a model. Our senses interpret all phenomenon in terms of models. We have constructed a model of the universe with our senses and our capacity to recall past experiences.

Perception is a result of how our senses interpret every phenomenon. Phenomena are represented by our interpretation of what our senses can gather about them. How much more fundamental can you get than our perception and how it works? It works because of electrons.

A cheese burger is a model. You can taste it, touch it, derive energy from it and enjoy it. Just as you can feel the heat, see the light etc of a light bulb that is only a light bulb because of electrons.

The cheese burger is only a cheese burger because of a herd of cattle in Brazil, a field of lettuce in Mexico and dairy cows in Idaho or oil refineries in New Orleans (for real or fake cheese). You don't see these elements and you probably will never see them all at the same time. You will only see a model example of them - the "cheese burger".

The majority of us don't see the process that goes into producing cattle, lettuce or cheese. The majority don't see the chlorophyll present in the lettuce. 99% of peopele are unaware that it is responsible for the absorption of light to provide energy for photosynthesis. The majority of us don't see the chlorophyll molecule that contains a magnesium atom held in a porphyrin ring. A large number of us can't even pronounce "chlorophyll". But we eat it. And that is our model of that particular phenomenon. Its a leafy thing that goes well in a cheese burger. Everything's a model of the next level of process.

At what level of process are electrons situated?

How does the model lattice explain "an electron" itself? Try it, I want to see it apply to an lepton.
 
  • #24
nannoh said:
Philosophically everything is a model.
You're right - philosophically.

But for millenia, humans have treated their five senses as empirical.
 
  • #25
DaveC426913 said:
You're right - philosophically.

But for millenia, humans have treated their five senses as empirical.

Yeah and for all but the last half-millenium they believed fallacies about the world, animal life, and themselves because they naively took what their five senses told them as the whole story. Their senses brought them models, just every view of the world must, but those models were dead wrong.

It wasn't till scientists began to get beyond the limitations of the senses (telescopes and microscopes) that progress toward more accurale models could be found.
 
  • #26
Weather Freak said:
My friend and I came to wondering if there is indisputable proof that electrons exist?

As others pointed out, everything you are aware of can be an illusion: you can be a body-less mind which is having a dream of a real world (that philosophical stance is called solipsism). Starting from that, every statement about the reality of something contains something of a hypothesis, which is only made to "organize your subjective experience" or "make sense of your dream".
But doing that is highly useful and practical. It is a very practical and useful hypothesis that "your friend is a person a bit like you that really exists", and "that you have a body" etc... Many of these hypotheses are so evident to us that we make them without even putting them in doubt - especially sensations that seem to come "directly from our 5 senses". We have difficulties accepting that what comes from our senses would just be an illusion. That said, the further we get away from things directly coming from our senses, the more we are ready to consider their illusionary character.

But deep down, it all comes down to the same: we're making hypotheses about an external reality in order for us to help us organize our subjective experience.
 
  • #27
pibomb said:
How does the model lattice explain "an electron" itself? Try it, I want to see it apply to an lepton.

Another thing that has been studied lately is quantum mechanics and the quantum state which is thought to produce emergent phenomena such as electrons and leptons. This could be the answer to your inquiry in that electrons, sub-atomic particles, photons and gravity are what we are able to view as models of the quantum state. Not unlike how a cheese burger is a model or emergent phenomenon of the agricultural system.
 
  • #28
selfAdjoint said:
Yeah and for all but the last half-millenium...
...depending on who you ask. We deal with plenty of thousand+ year old fallacies here. Science, though, hasn't worked that way since the scientific method was introduced (which is maybe what you were getting at).
nanoh said:
At what level of process are electrons situated?
Well, that depends on the phenomena. With a CRT, for example, the electrons are only one step removed from being directly visible, just like any other thing we see - separated only by the mechanism by which the electron's energy is converted to light.

One level down means I don't need to know much more specific info about it to know that it is an electron. Similarly, I just ate a cheeseburger, and I don't need to know anything about chlorophyl to know lettuce exists.
pibomb said:
How does the model lattice explain "an electron" itself? Try it, I want to see it apply to an lepton.
I know lettuce exists because I ate it in a cheeseburger a few minutes ago. If I want to know about chlorophyl, I need to go back several steps into the chemistry/biology of lettuce. So see, that doesn't have anything to do with whether lettuce (or a chesseburger) exists. Though one is part of the other, it is still a separate question that doesn't need to be answered to get a useable answer to the first question.

And that's the level of detail we're talking about with electrons and where the fallacy comes into play. If you go deep enough with anything, you'll reach a place where science cannot adequately explain what is going on. But just because we can't answer every question people have about electrons, that doesn't mean cheeseburgers don't exist.

[edit: that last part is only half a joke: If we could not say that electrons exist due to unanswered questions about them, then we could also not say that cheeseburgers exist because there are electrons in cheeseburgers and they play a pretty big role in determining what a cheeseburger is and how it "works".]
 
  • #29
DaveC426913 said:
You're right - philosophically.

Literally. If the model happens to be a true and complete description of the essence it seeks to describe, we can never know.

A favorite quote of mine.
The electron is not as simple as it looks.
-- (William) Lawrence Bragg, British Physicist(1890-1971)
 
  • #30
russ_watters said:
...depending on who you ask. We deal with plenty of thousand+ year old fallacies here. Science, though, hasn't worked that way since the scientific method was introduced (which is maybe what you were getting at).
Well, that depends on the phenomena. With a CRT, for example, the electrons are only one step removed from being directly visible, just like any other thing we see - separated only by the mechanism by which the electron's energy is converted to light.

One level down means I don't need to know much more specific info about it to know that it is an electron. Similarly, I just ate a cheeseburger, and I don't need to know anything about chlorophyl to know lettuce exists. I know lettuce exists because I ate it in a cheeseburger a few minutes ago. If I want to know about chlorophyl, I need to go back several steps into the chemistry/biology of lettuce. So see, that doesn't have anything to do with whether lettuce (or a chesseburger) exists. Though one is part of the other, it is still a separate question that doesn't need to be answered to get a useable answer to the first question.

And that's the level of detail we're talking about with electrons and where the fallacy comes into play. If you go deep enough with anything, you'll reach a place where science cannot adequately explain what is going on. But just because we can't answer every question people have about electrons, that doesn't mean cheeseburgers don't exist.

[edit: that last part is only half a joke: If we could not say that electrons exist due to unanswered questions about them, then we could also not say that cheeseburgers exist because there are electrons in cheeseburgers and they play a pretty big role in determining what a cheeseburger is and how it "works".]

Russ, where's the cheeseburger now and would you recognize it as such were it to reappear!:wink:
 
  • #31
Ivan Seeking said:
Literally. If the model happens to be a true and complete description of the essence it seeks to describe, we can never know.

A favorite quote of mine.
The electron is not as simple as it looks.
-- (William) Lawrence Bragg, British Physicist(1890-1971)

The funny thing is that every model - that is every phenomenon - carries with it and within it the whole and unmitigated truth about its existence. It is our own physical limitations that forces us to question its origin/existence and go further and farther down the rabbit hole looking for proof of its existence, mechanism and foundations. We even invent instruments to help us do so. There must be an easier way to understand the truth.
 
  • #32
nannoh said:
Another thing that has been studied lately is quantum mechanics and the quantum state which is thought to produce emergent phenomena such as electrons and leptons. This could be the answer to your inquiry in that electrons, sub-atomic particles, photons and gravity are what we are able to view as models of the quantum state. Not unlike how a cheese burger is a model or emergent phenomenon of the agricultural system.

I know you are referring to an electron in a system but what about itself? If your model paradigm (no pun) is right, then can it describe single entities? Even is they are "models of the quantum state" explain how this is so and how it differentiates them from each other.
 
  • #33
nannoh said:
The funny thing is that every model - that is every phenomenon - carries with it and within it the whole and unmitigated truth about its existence.

The model and the phenomenon are two completely different things. The phenomenon can be observed or measured, but we can't know if a model used to describe that phenomenon is complete or a statement of essential truth. We can only say that it agrees with that observed.
 
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  • #34
Weather Freak said:
Sure, we can "see" them and "interact" with them in these ways, but it's more of an interaction with a collection of them...
It was in anticipation of just this that my first post in this thread lists various experiments that measure interactions with a single electron...something you seem to have completely ignored.
 
  • #35
Ivan Seeking said:
The model and the phenomenon are two completely different things. The phenomenon can be observed or measured, but we can't know if a model used to describe that phenomenon is complete or a statement of essential truth. We can only say that it agrees with that observed.

Well, yeah, I'm using the term "model" rather losely. I'm sort of saying that emergent phenomena presents to us a model of quantum activity. There's really no way to see the nanoscopic quantum state in an emergent phenomenon. It takes a bunch of physicists a bunch of years, bunches of equations and miles of cyclotron to measure waves and collisions to see the quantum state.

About the single electron question. Gravitons, electrons, photons and all those increments of measurement that end in "on" are just that, increments of measurment. The words describe a particular yet arbitrary amount of a wave of electromagnetic activity.

Isn't a single electron simply that which we have singled out as the smallest unit of a wave of electromagnetic activity that can possibly be observed by us and our puny instruments?
 

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