Physics Forums

Page 1 of 5   1   2   3   4  >   Last »

## What exactly is an electron?

HI,
Firstly I'd like to open with I know what an electron is and I know all about its charge and the role it plays in electricity, current, free electron model etc etc.
My question is what is an electron 'made' out of? My reasoning is that it cant be made out of anything physical as its charge would distribute evenly throughout its-self and would fly apart as every part of the electron would repel every other part of the electron.
In physics the electron is thought of as a mathematical point particle but in a 3-spacial dimensional universe a 1-d object cant physically exist so that rules that out.
If i could magically enlarge an electron to the size of a car what would i physically see?
or is there even any credence to asking a question like that?

PhysOrg.com  physics news on PhysOrg.com  >> Promising doped zirconia>> New X-ray method shows how frog embryos could help thwart disease>> Bringing life into focus

I'd like to know, too.  We don't have a model of elementary particles which gives them any structure.  Many people have tried to build such a model (Lorentz, Poincare, Feynman ...), but no one has succeeded.  Modern Quantum Field Theory assumes that elementary particles are pointlike entities with no internal structure.  Whether this is true or whether this is only an approximation is an open question.  "The Feynman Lectures on Physics" Vol 2, Chapter 28 gives a very readable history of these attempts.

Mentor  What exactly is a lion?  If I pointed at one and said "that's a lion", wouldn't that be an acceptable answer?  What is unacceptable about pointing at an electron and saying "that's an electron?"  Until you've answered that question, it will be difficult to write an answer that will satisfy you.

Recognitions:
Science Advisor

## What exactly is an electron?

To conclude: To the best of our knowledge today (i.e., in this case the standard model of particle physics) the electron is an elementary spin-1/2 Dirac particle with one negative elementary charge and a mass of about $511 \; \mathrm{keV}/c^2$. It's a lepton, i.e., participates only in the electroweak interaction (let alone gravitation, which acts universally on anything that has energy and momentum).

Recognitions:      Gold Member  When you ask what something is, the most accurate description is detailing the physical properties of it, such as mass, charge, etc. Asking what it "really" is simply doesn't make any sense, as there is no more available information. Any answer is simply speculation.

Recognitions:
Science Advisor

Quote by CF.Gauss 					 				 				My question is what is an electron 'made' out of? [...] In physics the electron is thought of as a mathematical point particle [...] If i could magically enlarge an electron to the size of a car what would i physically see? or is there even any credence to asking a question like that?
In enlarging quantum objects one makes their quantum properties disappear. Macroscopic objects behave classically.

The electron is an elementary particle, hence not composed of anything but itself. But it is not a point - only pointlike (which means, the formal, unobservable, bare electron in the defining action is a point). Due to radiative corrections stemming from the renormalization procedure for relativistic quantum field theories, an observable, renormalized electron has a positive charge radius (though far too small to be probed experimentally with current methods).

Blog Entries: 1 				 				 				 				         Recognitions:        Science  Advisor  What is the charge radius of the electron predicted to be? Order of magnitude.

Recognitions:      Gold Member  CF.Gauss why do electrons not look like sparks/lightening?

Quote by nitsuj 					 				 				CF.Gauss why do electrons not look like sparks/lightening?
I think the lightning you see is actually emission from partially ionized nitrogen and oxygen plasma.

Recognitions:      Gold Member  Yes, and when I "see" anything else what am I "seeing"? Say fire for example, am I seeing fire or what.  Simular to what Vanadium 50 said "What exactly is a lion? If I pointed at one and said "that's a lion", wouldn't that be an acceptable answer?"  an electron looks like a bzzt, and feels like a bzzt, so it must be a bzzt.

This question is similar to asking what is a photon?  Photons and electrons and other elementary particles are not actually little billiard balls that are flying around high speeds.  They are both quantum excitations of their respective fields.  The entire universe is filled with a photon field, and it's mostly empty.  You can think of it as an empty EM field as well.  At every point in space there is a quantum harmonic oscillator for each possible spatial frequency, and thing about quantum harmonic oscillators is that only allowed energy levels come in steps of hw.  The minimum energy of the oscillator is 3/2hw in 3 dimensions, and then it goes up to 5/2hw, then 7/2 hw, etc.  One step above the zero-point level is considered one photon at that spatial frequency.  The photon could have a range of frequencies, and be localized in some way, or be more spread out and less localized.  Just think of it of a field as an infinite set of harmonic oscillators at every point in space, and think of the particles as quantum vibrations of this field.  In a similar way, there is an electron field that fills of space with a zero-point energy, and it has certain linearly quantized energy levels above the zero level that indicate the number of electrons.  This explains why every electron has exactly the same mass, charge, spin, and g-factor.  Saying an electron is the same thing as saying a quantum vibration of the electron field, but the latter is too wordy.  The electron vibration can be localized, as in a vibration around an atom, or more spread out like a free particle, or an electron in a double slit experiment.  The big difference between the electron field and the photon field is that with electron vibrations, they can't stack directly on top each other.  This is described as the Pauli Exclusion rule.  The electron field is a fermion field, described by the Dirac equation.  Two electron vibrations can be in almost the same state very close to each other, but they can never occupy the same exact state.  I like to visual all quantum particles, whether they are photons or electrons, as 3 dimensional fuzz balls, and those fuzz balls oscillate and move around and sometimes disappear according the probabilistic laws of QFT.  It's the sudden collapse of the fuzz balls that's most shocking to me, (wavefucntion collapse is mysterious).

Recognitions:      Gold Member  Fastman, while your explanations seems to make sense, I am hesitant to really accept it, as I've never heard of "photon fields" or "electron fields" and the like. What model is this from?

You've heard of fermionic fields though right?  I just sort of made it up the terms "photon field" and "electron field" on the spot. http://en.wikipedia.org/wiki/Fermionic_field The electron field is just a type of fermionic field governed by the Dirac equation.  That's my definition anyway.  It's what helps me envision quantum field theory better.  The most disappointing aspect of the field theory is that it predicts a large zero-point energy.  It's been dismissed before, but now that dark energy is around, we need some explanation for why there is a negative energy field permeating the entire universe and causing cosmic acceleration.  The zero-point energy of the QFs were a candidate, but the calculations were done and it's 120 orders of magnitude larger than the measured value!  That's a terrible model error.  http://en.wikipedia.org/wiki/Zero-po..._and_cosmology

Recognitions:
Gold Member

Quote by Fastman99 					 				 				You've heard of fermionic fields though right?  I just sort of made it up the terms "photon field" and "electron field" on the spot.
Actually no. My knowledge of QFT is severely lacking. Thanks for the links by the way!

Recognitions:
Science Advisor

Quote by Bill_K 					 				 				What is the charge radius of the electron predicted to be? Order of magnitude.
$$10^{-16}cm$$ according to
http://adsabs.harvard.edu/cgi-bin/np...hDT.......130L

Mentor  False.  There is no prediction for the charge radius of the electron.  There are experimental limits suggesting that any charge radius must be smaller than some number, but the number that A. Neumaier posted is neither a prediction nor a measurement.

If you could magnify an electron to the size of a car,you would have to slow it down as well ,so as to observe the individual oscillations.

Page 1 of 5   1   2   3   4  >   Last »

Tags
electron

Thread Tools

|                                                   |                                        |         |
|---------------------------------------------------|----------------------------------------|---------|
| Similar Threads for: What exactly is an electron? |                                        |         |
| Thread                                            | Forum                                  | Replies |
|                                                   | High Energy, Nuclear, Particle Physics | 5       |
|                                                   | Introductory Physics Homework          | 8       |
|                                                   | Quantum Physics                        | 1       |
|                                                   | Classical Physics                      | 1       |
|                                                   | High Energy, Nuclear, Particle Physics | 1       |
{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "github"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "english_confidence": 0.9423501491546631, "perplexity_flag": "middle"}