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TheOther
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16 Aug 2019, 3:01 pm

In physics, there is constant discussion of electrons and photons.

But are they real particles, or are they merely useful abstractions?

To my knowledge, an electron or photon has never been the input or output of any experiment. When scientists talk about the electron shell, we are only ever given an area with a certain probability that an electron might be there at some point. Experiments such as the double slit experiment strongly suggest that light is best explained as a wave. How can we tell photons exist as discrete particles, as opposed to being something else (such as a particularly condensed point in a wave, like the peak of a wave in the ocean)?

If they are real, why can't we capture one somehow (instead of the probabilistic presences in an area notion that is used)?



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16 Aug 2019, 3:03 pm

Had learned about it in school. I've never seen them. :P



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16 Aug 2019, 3:08 pm

TheOther wrote:
To my knowledge, an electron or photon has never been the input or output of any experiment.
Have you really never heard of electronics or fiber-optics? What about cathode-ray tubes and lasers? There are instruments so sensitive that single electrons and photons have been detected. They are not mathematical abstractions, they are real things.


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16 Aug 2019, 3:11 pm

https://owlcation.com/stem/Millikans-Oi ... Experiment

Millikan's Oil Drop Experiment: How to Determine the Charge of an Electron



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TheOther
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16 Aug 2019, 3:21 pm

Fnord wrote:
TheOther wrote:
To my knowledge, an electron or photon has never been the input or output of any experiment.
Have you really never heard of electronics or fiber-optics? What about cathode-ray tubes and lasers? There are instruments so sensitive that single electrons and photons have been detected. They are not mathematical abstractions, they are real things.


But how do we know that they are discrete particles, as opposed to, say, a condensed segment of a wave (or multiple waves)?



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16 Aug 2019, 3:26 pm

TheOther wrote:
Fnord wrote:
TheOther wrote:
To my knowledge, an electron or photon has never been the input or output of any experiment.
Have you really never heard of electronics or fiber-optics? What about cathode-ray tubes and lasers? There are instruments so sensitive that single electrons and photons have been detected. They are not mathematical abstractions, they are real things.
But how do we know that they are discrete particles, as opposed to, say, a condensed segment of a wave (or multiple waves)?
First, read the articles. Then, contact a physicist to explain it all to you. They can be found at any four-year university with a physics department.


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16 Aug 2019, 3:38 pm



TheOther
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16 Aug 2019, 3:43 pm

Fnord wrote:
TheOther wrote:
Fnord wrote:
TheOther wrote:
To my knowledge, an electron or photon has never been the input or output of any experiment.
Have you really never heard of electronics or fiber-optics? What about cathode-ray tubes and lasers? There are instruments so sensitive that single electrons and photons have been detected. They are not mathematical abstractions, they are real things.
But how do we know that they are discrete particles, as opposed to, say, a condensed segment of a wave (or multiple waves)?
First, read the articles. Then, contact a physicist to explain it all to you. They can be found at any four-year university with a physics department.


I understand that photons and electrons are descriptions of real phenomena that we observe. My question is perhaps more natural philosophy (which is what science used to be called anyways) in nature: do the terms refer to real, discrete particles, or do they refer to mathematical concepts and observations which may or may not be discrete particles?

Why is such a question not permissible in a sub-forum for scientific discussion? I think it is quite suitable for an interesting armchair discussion, and there are many interesting consequences to either answer as well.



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16 Aug 2019, 3:46 pm


This guy had put together an entertaining video to try and explain it all
that relates to the proton and electron

just a quick note
i am not a physics expert, although i have a degree that uses some basic physics plus complex but not advance maths
i haven't studied this yet, never really could afford the parts to create a time machine, so didn't bother
alas, perhaps in another world or parallel lifetime where people haven't robbed every thing i have
and where people are actually really nice to each other....



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16 Aug 2019, 3:59 pm

TheOther wrote:
In physics, there is constant discussion of electrons and photons.

But are they real particles, or are they merely useful abstractions?

To my knowledge, an electron or photon has never been the input or output of any experiment. When scientists talk about the electron shell, we are only ever given an area with a certain probability that an electron might be there at some point. Experiments such as the double slit experiment strongly suggest that light is best explained as a wave. How can we tell photons exist as discrete particles, as opposed to being something else (such as a particularly condensed point in a wave, like the peak of a wave in the ocean)?

If they are real, why can't we capture one somehow (instead of the probabilistic presences in an area notion that is used)?


As far as I'm aware, this is as yet unknown to man. They have been detected but their exact nature cannot be proven or disproven.

I ask the same question sometimes and light fascinates me. I often wonder if absolutely everything is energetic vibration based on a magnetic spin of some sort. A whole 'force field' thing seemed plausible to me the other day.



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16 Aug 2019, 4:50 pm

The oil drop experiment is most easily explained by assuming electrons with the same charge to weight ratio. I wonder if any else got to do experiments like that when they were in school? The school I went had a fortune invested in stuff to do that.

I remember an experiment involving radioactive Cobalt 60. Someone brought up playing with gears while we were doing it. Another student said they never got to play with gears, though he went to really expensive schools.



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16 Aug 2019, 5:01 pm

What you're perhaps getting at here is the nominalism/realism debate in philosophy, which like all such heated questions, is really a wordgame rather than a serious, answerable question.

It doesn't really make sense to question whether the physical world is really "out there", or whether it's an epiphenomenon of our consciousness, for what would it mean for it to be merely an epiphenomenon?

The bottom line is that there's no MORE reason to believe that electrons and photons are unreal than there is to believe the same thing about macroscopic matter; the former two can be observed with the same degree of certainty as the latter, in theoretically simple ways. It's perfectly possible to observe both singly.

Both electrons and photons exist as both particles and waves (de Broglie wavelength). The wave nature of electrons can be demonstrated through diffraction experiments, as well as being predicted by the simple de Broglie relation; the particle nature of photons can be demonstrated by the photoelectric effect, and the fact, predicted by Einstein, that photons will have momentum, which can also be demonstrated experimentally.



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17 Aug 2019, 5:17 am

Prometheus18 wrote:
...that photons will have momentum, which can also be demonstrated experimentally.


Momentum, but no mass (as seems now to be generally accepted? How? Another puzzle to add to the question of how light can be bent by gravity (or so it is claimed) but cannot be otherwise accelerated (light escapes massive stars at a constant velocity, we are told)?



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17 Aug 2019, 5:54 am

gwynfryn wrote:
Prometheus18 wrote:
...that photons will have momentum, which can also be demonstrated experimentally.


Momentum, but no mass (as seems now to be generally accepted? How? Another puzzle to add to the question of how light can be bent by gravity (or so it is claimed) but cannot be otherwise accelerated (light escapes massive stars at a constant velocity, we are told)?

There are ways of defining momentum that are equally as good as the old p=mv.

Light is bent (demonstrated in 1917) as a result of the curvature of space itself in the presence of mass; it still follows a trajectory described by a geodesic in the relevant curved space.



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21 Aug 2019, 7:28 pm

Electrons (and their anti-matter compliments, positrons) are indeed particles of matter. They both have mass and both carry charge. So, why then do they act like waves in some aspects is the question I often hear?

It is because both electrons and positrons are composed of electromagnetic energy. Each one contains 511 KeV of this energy. This can be measured directly during annihilation evens between the two particles. In that process, both particles are converted back into the electromagnetic energy that created them. The “light” energy that is given off will be at a right angle to the collision event and the two energies will be emitted at 180 degrees from each other.

Albert Einstein’s Special Theory of Relativity is followed in this case. The reverse process can be done, but can be much harder to control. It is called pair production. In both cases, the conversion goes at 100% efficiency. Since all matter and anti-matter is composed of electromagnetic energy, they will still retain some of the properties of the starting energy used to make up the particles.

What we consider properties of matter or anti-matter is dependent upon how the electromagnetic energy is shaped to make up the particles. String Theory is a method of explains how this happens, but it is incomplete at best. One major thing that is missing from String Theory is that electromagnetic energy must always have a net momentum vector (a directional path that it can travel) or it cannot exist. One cannot stop electromagnetic energy without it being converted into something else via a process like absorption.

I have been working for a few years on a method to correct String Theory into a usable form. Unfortunately, we do not have the technology to test it yet. It may not happen within my lifetime, but hopefully someday it can be tested.