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Indisputable Proof that Electrons Exist?

  1. Nov 26, 2006 #1
    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?
     
  2. jcsd
  3. Nov 26, 2006 #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).
     
  4. Nov 26, 2006 #3
    This may be cliché but what ever;

    Can you see the wind?
     
  5. Nov 26, 2006 #4

    Gokul43201

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    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
     
  6. Nov 26, 2006 #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"?
     
  7. Nov 26, 2006 #6

    DaveC426913

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    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.
     
    Last edited: Nov 27, 2006
  8. Nov 27, 2006 #7
    I see, so it's not a sphere at all, but rather the sphere is just how it is represented in the textbooks...?
     
  9. Nov 27, 2006 #8

    arildno

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    How have you proof that birds exist, and are not a figment of your imagination?
     
  10. Nov 27, 2006 #9
    I don't think it's a sphere, either. It is a point-particle with no internal constituents (as of today!).
     
  11. Nov 27, 2006 #10
    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.
     
  12. Nov 27, 2006 #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
     
  13. Nov 28, 2006 #12

    DaveC426913

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    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.
     
  14. Nov 28, 2006 #13

    Gokul43201

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    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?
     
  15. Nov 28, 2006 #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!
     
  16. Nov 28, 2006 #15

    russ_watters

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    Yeah. Its essentially a defnition.
     
  17. Nov 28, 2006 #16

    russ_watters

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    Stick your finger in a light socket and then try that statement again....

    [Note: do not stick your finger in a light socket]
    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.
     
  18. Nov 29, 2006 #17

    DaveC426913

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    Yes, but that's still inference of their existence. It's still a model.
     
  19. Nov 29, 2006 #18

    DaveC426913

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    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.
     
  20. Nov 29, 2006 #19
    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?
     
  21. Nov 29, 2006 #20

    russ_watters

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    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.
     
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