Is dimensionless singularity truly dimensionless?

[No-where-man]

I also have one quick question:
How can electron, quark, photon be dimensionless if the smallest quantum size limit-the Planck's length is below their size, since all of the particles are bigger in size than Planck's length?
Most likely, I'm misunderstanding something, but I don't know what exactly.

http://blogs.discovermagazine.com/b...you-dont-know-about-black-holes/#.UzphiVT_RXo

 

[No-where-man]

A little logic never hurts. Is it reasonable to assume an electron has infinite charge or mass density? I doubt you will find any credible scientist who would agree.

It might be worth exploring a parallel question - why is an electron not infinitely dense [i.e., a black hole]? For discussion, see http://cow.physics.wisc.edu/~ogelman/guide/e/ . This is a ridiculous proposition that entirely lacks observational support.

This is a good thing to know; that all credible physicists know that an electron does not really have infinite charge or infinite mass density after all.

 

[Drakkith]

I also have one quick question:
How can electron, quark, photon be dimensionless if the smallest quantum size limit-the Planck's length is below their size, since all of the particles are bigger in size than Planck's length?
Most likely, I'm misunderstanding something, but I don't know what exactly.

http://blogs.discovermagazine.com/b...you-dont-know-about-black-holes/#.UzphiVT_RXo

To quote the article (underlining mine):

At some point, the collapsing core will be smaller than an atom, smaller than a nucleus, smaller than an electron. It’ll eventually reach a size called the Planck Length, a unit so small that quantum mechanics rules it with an iron fist. A Planck Length is a kind of quantum size limit: if an object gets smaller than this, we literally cannot know much about it with any certainty.

All this says is that IF something is smaller than the Planck length, we simply cannot know anything about it. It's not saying that an object cannot be smaller than this length. Besides, I don't know where you're getting the idea that all particles are larger than this size. It's that the upper limit to their sizes are larger than this, which is a result of our measurement methods having finite accuracy and precision.

So, I'm asking you all what do you recommend what should I answer to him?
Is he right or wrong, of being so sure that particles are truly dimensionless?

Am I right when I say that is impossible to prove or disprove that particles are truly dimensionless because of the measurements and detections that technologies can provide which are all very limited?
I don't understand why is he such an absolutist?
If he is so sure about this than I guess for him there is no rule: in science there is nothing that can be proven or disproven, and that's golden rule for any scientist, or at least should be, if you're truly an objective scientist.

I don't know how to answer this since I don't know his rationale for claiming that particles have been proven to be point particles. I'd recommend asking him why he believes this.

 

[julcab12]

I also have one quick question:
How can electron, quark, photon be dimensionless if the smallest quantum size limit-the Planck's length is below their size, since all of the particles are bigger in size than Planck's length?
Most likely, I'm misunderstanding something, but I don't know what exactly.

http://blogs.discovermagazine.com/b...you-dont-know-about-black-holes/#.UzphiVT_RXo

...Maybe he is referring to the 18+ or so dimensionless parameter of Standard model. Anyways, QFT doesn't have a fundamental measurement since it is always has some adjustable parameters. It is subject to rescaled unless we have a Quantum theory that reduces energies less than some large energy to confine particle to a degree.. This is actually how they determine the mass of proton. They can only measure to a certain constraint and it can't be absolute. Those measurements has value but has unpredictable real quantities. (The link i provided has a good straight forward bird droppings/sublinks. Chapter b3-4 should give you a rundown).



...Instead of debating with your friend. Try to get as much info. Ask questions, investigate and re-evaluate. (He's more knowledgeable on the subject). BTW. Learn more on his/her language..^^

 

[craigi]

I also have one quick question:
How can electron, quark, photon be dimensionless if the smallest quantum size limit-the Planck's length is below their size, since all of the particles are bigger in size than Planck's length?

We've already discussed this. There is no proven significance of the Planck length, though modern theories of quantum physics take the Planck length as a minimum size of an object very seriously. They remain unproven. It's also worth reminding yourself of the scale comparision that I gave to see how small the Planck length really is.

...
So, I'm asking you all what do you recommend what should I answer to him?
Is he right or wrong, of being so sure that particles are truly dimensionless?
...
In the end what do you recommend me?

In all seriousness, my recommendation is that you politely excuse yourself from the argument. I don't see what either of you can gain by trying to defeat the other. Which of you is right comes down to subtleties of definitions, so if one of you does walk away the victor, it will be a very hollow victory.

 

[Chronos]

In the real world, you apply logic and causality - neither of which explains an infinitely dense charge or mass density.

 

[No-where-man]

In the real world, you apply logic and causality - neither of which explains an infinitely dense charge or mass density.

Sure, he will say than, that human logic has made mistakes through history-which is true, so, he will say, that if math says that dimensionless singularity, dimensionless particles, an infinitely dense charge and infinite mass density all do exist, becuase they are 100% proven to exist, and that all of this is 100% experimentally proven.

We've already discussed this. There is no proven significance of the Planck length, though modern theories of quantum physics take the Planck length as a minimum size of an object very seriously. They remain unproven. It's also worth reminding yourself of the scale comparision that I gave to see how small the Planck length really is.

What do you exactly mean? You mean that is particles are dimensionless despite the Planck's length-which is the quantum size limit, or that is uncertain (and it will always be uncertain) that particles are truly dimensionless?

In all seriousness, my recommendation is that you politely excuse yourself from the argument. I don't see what either of you can gain by trying to defeat the other. Which of you is right comes down to subtleties of definitions, so if one of you does walk away the victor, it will be a very hollow victory.

Trust me, I did not argue with this guy who knows physics very good, this is not a fight like you thought it is, the only thing I was asking him, why is so sure about what he is saying about dimensionless objects; sure we have mathematics and experimantal evidences, but it's far from being 100% proven as he claims it is.
What I can see in the forums that none here is absolutist when it comes dimensionlessness, dimensionless particles, singularity and etc. none of you ever said or even thought that all of this in physics is 100% proven, you simply use words; it is uncertain-which is the only true thing (as you all specifically confirmed), because nothing in science can ever be 100% proven or disproven.

 

[No-where-man]

...Maybe he is referring to the 18+ or so dimensionless parameter of Standard model. Anyways, QFT doesn't have a fundamental measurement since it is always has some adjustable parameters. It is subject to rescaled unless we have a Quantum theory that reduces energies less than some large energy to confine particle to a degree.. This is actually how they determine the mass of proton. They can only measure to a certain constraint and it can't be absolute. Those measurements has value but has unpredictable real quantities. (The link i provided has a good straight forward bird droppings/sublinks. Chapter b3-4 should give you a rundown).



...Instead of debating with your friend. Try to get as much info. Ask questions, investigate and re-evaluate. (He's more knowledgeable on the subject). BTW. Learn more on his/her language..^^

Thanks for the support, as I said above to Chronos and Craigi in post #42, I did not try to debate him at all because he knows physics so much more than I do, basically what I was saying all the time to him, that nothing in science can be 100% proven or disproven, as well as the problems with measurements, and detection, there are always shreds of doubt that are present, and there is truly nothing 100% provable/proven/disproven-I think these statements are accurate, and yes I will look up to this link that you gave me, and I will listen to your advices.
Big thanks to all for help and advices.

 

[craigi]

Thanks for the support, as I said above to Chronos and Craigi in post #42, I did not try to debate him at all because he knows physics so much more than I do, basically what I was saying all the time to him, that nothing in science can be 100% proven or disproven, as well as the problems with measurements, and detection, there are always shreds of doubt that are present, and there is truly nothing 100% provable/proven/disproven-I think these statements are accurate, and yes I will look up to this link that you gave me, and I will listen to your advices.
Big thanks to all for help and advices.

The problem that I have with this thread is that you're clearly using it to generate ammunition for an argument that you're having on a Croation religion forum, here: http://www.forum.hr/showthread.php?p=49381433

You're not following what we're telling you, rather you cherry-pick the parts that suit your purpose then throw them at someone else without context, in the other thread. It doesn't matter which side of the religious debate that you're on, this isn't how science works and it isn't how this forum works either. It doesn't form a reasonable basis for debate in theology or philosophy either, for that matter. Contrary, to what we've suggested previously, if you take anything away from this thread it should be that.

I don't speak Crotatian and machine translations aren't particularly reliable, but it doesn't seem that the guy in the other thread is telling you anything different to what we're telling you here. It seems like you're arguing with different physicists who agree on the same concepts, but filtering them through a one-man Chinese whisper machine.

 

[No-where-man]

The problem that I have with this thread is that you're clearly using it to generate ammunition for an argument that you're having on a Croation religion forum, here: http://www.forum.hr/showthread.php?p=49381433

You're not following what we're telling you, rather you cherry-pick the parts that suit your purpose then throw them at some one else without context, in the other thread. It doesn't matter which side of the relgious debate that you're on, this isn't how science works and it isn't how this forum works either. It doesn't form a reasonable basis for debate in theology or philosophy either, for that matter. Contrary, to what we've suggested previously, if you take anything away from this thread it should be this.

Trust me, I pick no side at all, if there is a side I pick, its the side of pure science. We were simply discussing about if it's 100% proven that particles are dimensionless and about singularity, so although the thread is from religion forum, the theme that NOD and I were discussing were based purely on science and what is 100% proven and what is 100% disproven; plus the poster is an obviously a physicist who knows what he is talking about and who is using science/physics for arguments, but he is absolutely sure that what he says about the existence of dimensionlessnes, dimensionless particles and dimensionless singularity are 100% mathematically and 100% experimentally proven and that the existence of dimensionlessnes, dimensionless particles and dimensionless singularity all are 100% irrefutably, 100% proven scientific facts.

But in this thread on physics forums, I see that it's obvious that story with is far from over, since nothing in science can be 100% proven or disproven.
I will listen to all of your advices, what you, Craigi, and the rest of people/physicists here on this forum suggested me to do.
Big thanks to all.

 

[craigi]

Trust me, I pick no side at all, if there is a side I pick, its the side of pure science. We were simply discussing about if it's 100% proven that particles are dimensionless and about singularity, so although the thread is from religion forum, the theme that NOD and I were discussing were based purely on science and what is 100% proven and what is 100% disproven; plus the poster is an obviously a physicist who knows what he is talking about and who is using science/physics for arguments, but he is absolutely sure that what he says about dimensionlessnes, dimensionless particles and dimensionless singularity is 100% mathematically and 100% experimentally proven, as in this thread it's obvious that story is far from over, since nothing in science can be 100% proven or disproven.
I will listen to advices, what you, Craigi, and the rest of people/physicists here on this forum suggested me to do.
Big thanks to all.

If you want to discuss science on a science forum, it doesn't make a lot of sense to cast doubt on the scientific method when you're presented with a conclusion that you don't like. Scientists are, of course, aware that to prove anything we need to make a philosophical assumption about the validity of the method, but it should be no surprise to you that we don't debate this assumption within the field of science.

You can see an detailed description here: http://en.wikipedia.org/wiki/Scientific_method, but for obvious reasons this isn't up for discussion on this forum.

 

[No-where-man]

If you want to discuss science on a science forum, it doesn't make a lot of sense to cast doubt on the scientific method when you're presented with a conclusion that you don't like. Scientists are, of course, aware that to prove anything we need to make a philosophical assumption about the validity of the method, but it should be no surprise to you that we don't debate this assumption within the field of science.

You can see an detailed description here: http://en.wikipedia.org/wiki/Scientific_method, but for obvious reasons this isn't up for discussion on this forum.

Actually this was indeed discussed in science sub-forum in the same forum as well, I will give you a link if you don't believe me:
http://www.forum.hr/showthread.php?t=818634

I posted the same thing that you were answering me as well as the fact there are posters who know physics in this thread in science sub-forum and they agreed with me.
This NOD for some reason kept continuing to be absolutist on Religion sub-forum, claiming that when it comes to dimensionless particles, singularity and etc, is all 100% proven.
Sure NOD does know physics but there other people on the forum who know more physics than he does, but unlike NOD, some other posters who truly know physics are not absolutists like NOD is, because they know, unlike NOD, that there is always that degree of uncertainty.

 

[craigi]

Actually this was indeed discussed in science sub-forum in the same forum as well, I will give you a link if you don't believe me:
http://www.forum.hr/showthread.php?t=818634

I posted the same thing that you were answering me as well as the fact there are posters who know physics in this thread in science sub-forum and they agreed with me.
This NOD for some reason kept continuing to be absolutist on Religion sub-forum, claiming that when it comes to dimensionless particles, singularity and etc, is all 100% proven.
Sure NOD does know physics but there other people on the forum who know more physics than he does, but unlike NOD, some other posters who truly know physics are not absolutists like NOD is, because they know, unlike NOD, that there is always that degree of uncertainty.

Case closed.

This thread should be too.

 

[No-where-man]

Here is a weird question: Does gravity has a size at all?
Yes, gravity is a force, but does it have a size, or it is completely dimensionless?
I'm asking this because everything that has to do with gravity is/are basically effects of gravity and not the gravity itself.
For that matter, does a force/any force have a size, and does energy have a size at all, or what we can see everywhere in the universe, are simply effects of forces and energy?
I'm not sure if I asked this question right or wrong.
I'm not sure how to ask this question.

I'm opened to other posters' suggestions, opinions and whatever.
Big thanks in advance to all.

 

[Drakkith]

Here is a weird question: Does gravity has a size at all?
Yes, gravity is a force, but does it have a size, or it is completely dimensionless?
I'm asking this because everything that has to do with gravity is/are basically effects of gravity and not the gravity itself.
For that matter, does a force/any force have a size, and does energy have a size at all, or what we can see everywhere in the universe, are simply effects of forces and energy?
I'm not sure if I asked this question right or wrong.
I'm not sure how to ask this question.

That really depends on what you mean by "size". By the way you've worded your question I assume you're asking if it has physical dimensions like a physical object would. In that case, no, gravity does not have a size because it is not an object. Gravity takes up no space. It has no volume.

Of course, I'm sure someone will point out the event horizon of a black hole, but that is also not a physical object. An infalling observer would never know they crossed the event horizon. It is merely the radius where the strength of gravity won't let even light escape.

Also, by "dimensionless", are you asking about dimensionless quantities?

 

[skydivephil]

Nothing in science is ever 100% proved. we can get to levels of evidence that are overwhelming and silly to doubt but that's not quite the same thing
Two short articles on singularities I think you should read:
http://www.einstein-online.info/spotlights/big_bangs
http://plus.maths.org/content/what-happened-big-bang

 

[No-where-man]

That really depends on what you mean by "size". By the way you've worded your question I assume you're asking if it has physical dimensions like a physical object would. In that case, no, gravity does not have a size because it is not an object. Gravity takes up no space. It has no volume.

Of course, I'm sure someone will point out the event horizon of a black hole, but that is also not a physical object. An infalling observer would never know they crossed the event horizon. It is merely the radius where the strength of gravity won't let even light escape.

Also, by "dimensionless", are you asking about dimensionless quantities?

Hi, Drakkith, big thanks for your reply, and yes, I actually meant on both.
Also, if you by size and volume, than event horizon of the black hole and the black hole itself are both physical effects of gravity, but not the gravity/gravitational force/energy itself.

Also, we have physical effects of EM force/energy everywhere in entire universe, but EM force/energy does not have size at all, the same thing/principle is equally the same for strong nuclear force, weak nuclear force and all forms of energy-obviously, dimensionlessness does exist.

Regarding dimensionless quantities-can you recommend an physics book about them, the only thing I read was on wikipedia just in short, but I want to know and study more about dimensionless quantities in a more detailed way.

 

[No-where-man]

Nothing in science is ever 100% proved. we can get to levels of evidence that are overwhelming and silly to doubt but that's not quite the same thing
Two short articles on singularities I think you should read:
http://www.einstein-online.info/spotlights/big_bangs
http://plus.maths.org/content/what-happened-big-bang

I was thinking more about terms in physics like force and energy-the fact we can only see physical effects of all forms of forces and the forces themselves, we can only see physical effects of all kinds of forms of energy, but not the energy itself, because neither forces or forms energy themselves do not have physical size-we only have their physical effects-and who says dimensionlessness does not exist, when it does if we include force and energy.
BTW, huge thanks for the links.

 

[iDimension]

This is a complicated issue that cannot be answered in just a few sentences. Elementary particles are considered to be "point-like", but this does not mean that they are truly dimensionless objects. The reality is that the concept of size isn't very meaningful at the quantum level for fundamental particles.

Size doesn't make sense on the galactic level either. Galaxies, distances, the size of stars etc but we don't just say they're infinitely large.

The way I see it is no matter how small an object is, for it to physically exist, it must have some dimensions, no matter how small.

I know things are not always straight forward in physics but the scientific community are extremely poor at getting across a point in a way that more people can understand. Singularities fly in the face of everything we know to be true. The math says its false, logic says its false, chances are it's probably false.

Having an object with 0 dimensions means you don't actually have an object. Afterall if elementary particles were point like and had 0 dimensions then you could never create a 2D or 3D object...

 

[Bill_K]

The way I see it is no matter how small an object is, for it to physically exist, it must have some dimensions, no matter how small.

The way you see it differs from mainstream physics.

the scientific community are extremely poor at getting across a point in a way that more people can understand.

Just because a point is difficult to understand does not mean it is false.

Singularities fly in the face of everything we know to be true. The math says its false, logic says its false, chances are it's probably false. Having an object with 0 dimensions means you don't actually have an object.

The math says that elementary particles are pointlike. So far all experiments conform to this.

Afterall if elementary particles were point like and had 0 dimensions then you could never create a 2D or 3D object...

You are apparently confusing zero size with zero number of dimensions.

 

[iDimension]

Just because a point is difficult to understand does not mean it is false.

It’s not that it’s difficult to understand, it’s just that it’s impossible given what we know to be true.

I singularity is described as being an object. I argue that an object cannot physically exist without having some physical dimensions... By all means explain to me how an object can exist, without have a single dimension... Love, gravity, height and momentum for example don't have any dimensions, but we don't regard them as being physical objects. See where I'm coming from? Saying a particle is a physical object with 0 dimensions is like saying height is an object.

The math says that elementary particles are pointlike. So far all experiments conform to this.

To a lot of people saying something is "pointlike" is quite ambiguous. I can make a point in a piece of paper and it would appear pointlike, but it's 3 dimensional. When you say pointlike do you mean dimensionless? Or just an immeasurably small 3 dimensional object?

You are apparently confusing zero size with zero number of dimensions.

An object is defined by its dimensions isn't it? If I take a 3 dimensional object and remove all 3 of its dimensions, the object no longer exists.

Like I said I'm simply a spectator here on the forums so please don't think I'm challenging what you're saying, I'm simply trying to understand your impression of a 0 dimensional object.

 

[Bill_K]

To a lot of people saying something is "pointlike" is quite ambiguous. I can make a point in a piece of paper and it would appear pointlike, but it's 3 dimensional. When you say pointlike do you mean dimensionless? Or just an immeasurably small 3 dimensional object?

Pointlike means a three-dimensional object which current theory predicts to be a mathematical point (zero size, but still three-dimensional!). Current experimental evidence is consistent with this, meaning that if the particle does have a nonzero size, that size would have to be smaller than anything we have been able to detect.

The resolving power of an experiment (a collision, say) improves as you increase the energy. The best knowledge we have comes from the LHC, with energies in the TeV range, corresponding to a resolving power of the order 10^-17 cm. And we have not yet seen any indication, so any nonzero size would have to be smaller than that.

 

[No-where-man]

Pointlike means a three-dimensional object which current theory predicts to be a mathematical point (zero size, but still three-dimensional!). Current experimental evidence is consistent with this, meaning that if the particle does have a nonzero size, that size would have to be smaller than anything we have been able to detect.

The resolving power of an experiment (a collision, say) improves as you increase the energy. The best knowledge we have comes from the LHC, with energies in the TeV range, corresponding to a resolving power of the order 10^-17 cm. And we have not yet seen any indication, so any nonzero size would have to be smaller than that.

I think you and Drakkith both missed the point. Quantum physicists always say and warn us that size in quantum world and on quantum level do not have much meaning-nobody explained, why?
It seems to me more and more that definition of physical size and physical dimensions on sub-atomic level and on quantum level is not physical size on macroscopic level.
So, the man question is: do all the sub-atomic particles have physical size and physical dimensions at all?

It seems to me when it comes purely physical size and physical dimensions we can talk about only for macroscopic world/classic physics/general and special theory of relativity, while physical size and physical dimensions do not exist at all on quantum level (quantum physics/mechanics)?

Do physicists mean that when they repeatedly say physical size and physical dimensions do not mean much or they do not mean anything at all on sub-atomic and quantum level?

What do scientists exactly mean when they say physical size and physical dimensions do not mean much or they both do not mean anything at all on sub-atomic and quantum level?
Big thanks to all.

Besides like I said gravity and all other fundamental forces (electromagnetism, weak nuclear force, strong nuclear force), and all forms of energy, as well the energy itself do not have physical size and do not have physical dimensions at all, since they are not physical objects, they do not take up space, they do not have volumes, we can only see their effects and influences on space/environment.

Black hole's event horizon is not the size of gravity, it is the result, the effect and the influence of extreme gravitational force, but gravity/gravitational force itself does not have any kind of physical size/dimensions.

Like I said before, event horizon of the black hole and the black hole itself both have size and volume (radius and diameter), but both event horizon of the black hole and the black hole itself are both effects, results and influences and "products" of (extreme) gravity, but not the gravity/gravitational force/energy itself.

 

[Chronos]

Until we can measure things down to the Planck scale, this argument is meaningless. That is unlikely to change given the energy required to probe that length scale.

 

[No-where-man]

Until we can measure things down to the Planck scale, this argument is meaningless. That is unlikely to change given the energy required to probe that length scale.

I truly hope this will one day be possible!?

 

[julcab12]

I think you and Drakkith both missed the point. Quantum physicists always say and warn us that size in quantum world and on quantum level do not have much meaning-nobody explained, why?
It seems to me more and more that definition of physical size and physical dimensions on sub-atomic level and on quantum level is not physical size on macroscopic level.
So, the man question is: do all the sub-atomic particles have physical size and physical dimensions at all?

It seems to me when it comes purely physical size and physical dimensions we can talk about only for macroscopic world/classic physics/general and special theory of relativity, while physical size and physical dimensions do not exist at all on quantum level (quantum physics/mechanics)?

Do physicists mean that when they repeatedly say physical size and physical dimensions do not mean much or they do not mean anything at all on sub-atomic and quantum level?

What do scientists exactly mean when they say physical size and physical dimensions do not mean much or they both do not mean anything at all on sub-atomic and quantum level?
Big thanks to all.

Besides like I said gravity and all other fundamental forces (electromagnetism, weak nuclear force, strong nuclear force), and all forms of energy, as well the energy itself do not have physical size and do not have physical dimensions at all, since they are not physical objects, they do not take up space, they do not have volumes, we can only see their effects and influences on space/environment.

Actually in Quantum level we can have statistical boundaries that may have a average size (not absolute) in the form of scaling/quantize scale. For instance, electrons — for all we know they are point-like, with zero size, they’re at least 100,000,000 times smaller in diameter than atoms. The nucleus is also very tiny, though larger than the electrons; its size has been measured, and is about 10,000 to 100,000 times smaller in diameter than its atom. The only difference in macroscale is that we perceived some appearance of containment/limitation/separation/solidity/stillness when in fact when we zoom in on an object it will appear jittery.

 

[No-where-man]

Actually in Quantum level we can have statistical boundaries that may have a average size (not absolute) in the form of scaling/quantize scale. For instance, electrons — for all we know they are point-like, with zero size, they’re at least 100,000,000 times smaller in diameter than atoms. The nucleus is also very tiny, though larger than the electrons; its size has been measured, and is about 10,000 to 100,000 times smaller in diameter than its atom. The only difference in macroscale is that we perceived some appearance of containment/limitation/separation/solidity/stillness when in fact when we zoom in on an object it will appear jittery.

Big thanks for your answers, however, one quick question: If electrons and whatever else is/are 100 000 000 times smaller than diameter of one, single atom, why is it considered zero-size, since 100 000 000 times smaller size than the size and diameter of one, single atom is still the size that is NOT zero (0).

 

[julcab12]

Big thanks for your answers, however, one quick question: If electrons and whatever else is/are 100 000 000 times smaller than diameter of one, single atom, why is it considered zero-size, since 100 000 000 times smaller size than the size and diameter of one, single atom is still the size that is NOT zero (0).

Zero-size is a mathematical abstraction/description not to be confused with the classical zero/ordinarily imagined point in space or zero. They only say it is zero in a different context. We assume it has circumstantial scale using comparison.

 

[Drakkith]

I think you and Drakkith both missed the point. Quantum physicists always say and warn us that size in quantum world and on quantum level do not have much meaning-nobody explained, why?

Are you asking why no one explained?

It seems to me more and more that definition of physical size and physical dimensions on sub-atomic level and on quantum level is not physical size on macroscopic level.
So, the man question is: do all the sub-atomic particles have physical size and physical dimensions at all?

It's complicated because the particles act like point-like objects if you do certain experiments, but act like extended objects if you do other experiments. It's difficult to make a distinction when it's one smooth continuum between the two extremes.

It seems to me when it comes purely physical size and physical dimensions we can talk about only for macroscopic world/classic physics/general and special theory of relativity, while physical size and physical dimensions do not exist at all on quantum level (quantum physics/mechanics)?

Not true. Quantum physics requires physical dimensions. You literally can't formulate it without them.

Do physicists mean that when they repeatedly say physical size and physical dimensions do not mean much or they do not mean anything at all on sub-atomic and quantum level?

They mean that the size of a particle is hard to define concretely, not that physical dimensions are meaningless.

Besides like I said gravity and all other fundamental forces (electromagnetism, weak nuclear force, strong nuclear force), and all forms of energy, as well the energy itself do not have physical size and do not have physical dimensions at all, since they are not physical objects, they do not take up space, they do not have volumes, we can only see their effects and influences on space/environment.

Let's be sure to make a distinction between something not having a physical size and the concept of physical size not even applying. Forces and energy don't have physical dimensions because it simply doesn't apply at all, not because they are "point-like" or "dimensionless" like a particle may be.

Big thanks for your answers, however, one quick question: If electrons and whatever else is/are 100 000 000 times smaller than diameter of one, single atom, why is it considered zero-size, since 100 000 000 times smaller size than the size and diameter of one, single atom is still the size that is NOT zero (0).

We don't know that they are that size, it's just that they are at most no bigger than that. That's why he said that they are at least 100,000,000 times smaller than the atom. The reason we consider them to be point-like is most likely related to the fact that their size can be viewed as extremely small (point-like within measurement accuracy) or as an extended source depending on the experiment and how you look at it.

 

[Chronos]

It makes more sense to think of elementary particle sizes in terms of their Compton wavelength. For the electron this works out to about 4E-13 meters. A zero size electron invokes problems like infinite charge density, which most scientists view as unphysical. You can also think in terms of how close two such particles can get before they interact [collide]. We do this all the time in colliders. By statistical inference we can deduce the average size of elementary particle. These tend to agree with the size predicted by the Compton wavelength.

 

[iDimension]

I'm not sure if this is relevant to this discussion but if we take a region of space and divide it by 2, then divide it again, and again etc. Is there a physical limit as to how far you can go? Do we reach a stage where the space can no longer be divided and is this region of space "pointlike" and what you guys refer to as dimensionless space like singularities?

Just seems strange that we can have an electron that is pointlike and a singularity which is pointlike but clearly the singularity is smaller than the electron.

 

[No-where-man]

Are you asking why no one explained?

Yes.

It's complicated because the particles act like point-like objects if you do certain experiments, but act like extended objects if you do other experiments. It's difficult to make a distinction when it's one smooth continuum between the two extremes.

OK, but why than it is said they are dimensionless, I mean when you say something is point-like it can only mean that it's very, very small, because dimensionless mean that nothing point-like exists at all.

Not true. Quantum physics requires physical dimensions. You literally can't formulate it without them.

OK, I now understand.

They mean that the size of a particle is hard to define concretely, not that physical dimensions are meaningless.

OK, I now understand.

Let's be sure to make a distinction between something not having a physical size and the concept of physical size not even applying. Forces and energy don't have physical dimensions because it simply doesn't apply at all, not because they are "point-like" or "dimensionless" like a particle may be.

Could you be more specific?

Forces and energy do not have physical and physical dimensions because they do not possesses anything physical at all, because forces and energy are not physical at all.

Forces and energy by themselves do not exist in a physical world, but they all have physical manifestations, physical effects and physical influences on physical universe all the time which all are both physically detectable and physically measurable; forces and energy are not even point-like, since they are not points, and they do not possesses any kind of dimension/dimensions (including point-like) and both forces and energy do not possesses kind of physical size.

We don't know that they are that size, it's just that they are at most no bigger than that. That's why he said that they are at least 100,000,000 times smaller than the atom. The reason we consider them to be point-like is most likely related to the fact that their size can be viewed as extremely small (point-like within measurement accuracy) or as an extended source depending on the experiment and how you look at it.

OK, I understand now, they are at most 100 000 000 times smaller than the diameter of an atom, their size is extremely small, thanks.

 

[No-where-man]

I'm not sure if this is relevant to this discussion but if we take a region of space and divide it by 2, then divide it again, and again etc. Is there a physical limit as to how far you can go? Do we reach a stage where the space can no longer be divided and is this region of space "pointlike" and what you guys refer to as dimensionless space like singularities?

These same questions already torture me, as well, for several years.

Just seems strange that we can have an electron that is pointlike and a singularity which is pointlike but clearly the singularity is smaller than the electron.

Exactly, if singularity is much, much, much..., much smaller than other particle, how can both singularity and electron be point-like and without physical size and without physical dimensions?
Obviously, it is definitely sure that singularity immensely smaller than electron, so both singularity and electrons, quarks, bosons and etc. cannot be point-like?

And both singularity and sub-atomic particles (like electrons, quarks, bosons and etc.) both have physical size and physical dimensions (but extremely small, they seem to be point-like, since both electrons, quarks, bosons and etc. and singularity are so much small/tiny), otherwise singularity could never be/would never be smaller than electrons, quarks, bosons and etc., unless both singularity and electrons (and quarks and bosons and etc.) are equally without size, but that seems to be totally wrong hypothesis since singularity must be/is much smaller than electrons, which means that at least fundamental particles like electrons, quarks, bosons and etc. are not without size, since they are bigger/larger than singularity when it comes to physical size and physical dimensions!

This seems unexplainable, I'm a bit lost.

 

[No-where-man]

It makes more sense to think of elementary particle sizes in terms of their Compton wavelength. For the electron this works out to about 4E-13 meters. A zero size electron invokes problems like infinite charge density, which most scientists view as unphysical. You can also think in terms of how close two such particles can get before they interact [collide]. We do this all the time in colliders. By statistical inference we can deduce the average size of elementary particle. These tend to agree with the size predicted by the Compton wavelength.

Thanks for this explanation on how you measure average size (not absolute size) of any elementary particle.
Well, forces and energy by themselves do not exist in a physical world (but they all have physical manifestations, physical effects and physical influences on physical universe all the time which all are both physically detectable and physically measurable), either, so why would the problem with infinite charge density be such a great problem?

 

[iDimension]

These same questions already torture me, as well, for several years.
Exactly, if singularity is much, much, much..., much smaller than other particle, how can both singularity and electron be point-like and without physical size and without physical dimensions?
Obviously, it is definitely sure that singularity immensely smaller than electron, so both singularity and electrons, quarks, bosons and etc. cannot be point-like?

And both singularity and sub-atomic particles (like electrons, quarks, bosons and etc.) both have physical size and physical dimensions (but extremely small, they seem to be point-like, since both electrons, quarks, bosons and etc. and singularity are so much small/tiny), otherwise singularity could never be/would never be smaller than electrons, quarks, bosons and etc., unless both singularity and electrons (and quarks and bosons and etc.) are equally without size, but that seems to be totally wrong hypothesis since singularity must be/is much smaller than electrons, which means that at least fundamental particles like electrons, quarks, bosons and etc. are not without size, since they are bigger/larger than singularity when it comes to physical size and physical dimensions!

This seems unexplainable, I'm a bit lost.

Yes. I think it's just another case of physicists being bad at explaining things correctly. I have no doubt that they know exactly what they mean but when they relay that information to us, but they do not translate it in a way that makes sense to us.

I kinda get the feeling they're just playing with us sometimes lol. It's like me saying that a snail has a speed of 0km/h. I'm not wrong in saying that, but it's true speed is 0.3km/h for example.

So personally for me, when a physicist says that an object has a size of 0, they're wrong. They're wrong because if it's classed as an object, it must have some size. No matter how small it MUST have a size for us to call it an object.

Where is the logic in saying that we have two objects, both have a size of 0 and both have 0 dimensions, but one of them is larger than the other lol. It's just quite ridiculous to be honest. I wish they would make things more clearer when they explain it.

What they really mean to say is that the object is so small that for all intents and purposes it doesn't have a meaningful size but it does take up some sort of space. Again because by their logic, we can fit an infinite number of electrons inside a finite volume, which of course is hogwash.