# Thread: What's beyond the Neutrino?

1. As far as I know, the smallest thing we can actualy measure is the Neutrino. Have we been able to find anything smaller yet?

The real reason driving this post is that I've been thinking about two different things lately. One, what's the largest known thing in the universe and two, what's the smallest?
And after thinking about the largest, I quickly lost interest as that's just not quite as thought provoking to me. What really gets me thinking is the small stuff.

I feel that if an object can have mass, then there can always be one smaller. But that would mean there are no absolute smallest and only infinitely smaller.

For an object to have mass it has to be made of... something, and that something needs to be made of something, so on and so forth. Hence the infinately smaller.

I know no one knows, I just needed to post it >.<

2.

3. What makes you think the neutrino is the smallest thing? How big is it? How big is an electron? How big is a quark?

4. Originally Posted by ZedFighter
I feel that if an object can have mass, then there can always be one smaller. But that would mean there are no absolute smallest and only infinitely smaller.

For an object to have mass it has to be made of... something, and that something needs to be made of something, so on and so forth. Hence the infinately smaller.
Within the Standard Model all elementary particles are thought to be point-like ( ignore String Theory for the moment ), thus they cannot be subdivided into smaller parts.

5. Originally Posted by Markus Hanke
Originally Posted by ZedFighter
I feel that if an object can have mass, then there can always be one smaller. But that would mean there are no absolute smallest and only infinitely smaller.

For an object to have mass it has to be made of... something, and that something needs to be made of something, so on and so forth. Hence the infinately smaller.
Within the Standard Model all elementary particles are thought to be point-like ( ignore String Theory for the moment ), thus they cannot be subdivided into smaller parts.

Relative to the amount of knowledge yet to be gained, humans are still quite dumb. And for that reason I have so much difficulty wrapping my head around and truly understanding something like Point mass. I mean really, something can exist yet have no dimension... yeesh.

6. Originally Posted by ZedFighter
Relative to the amount of knowledge yet to be gained, humans are still quite dumb. And for that reason I have so much difficulty wrapping my head around and truly understanding something like Point mass. I mean really, something can exist yet have no dimension... yeesh.
Elementary particles are treated as point-like because it is mathematically convenient to do so, and because currently there exists no observational evidence to the contrary. That does not mean that in reality they actually are 0-dimensional objects, it only means that they appear to us like this, and that their description on this level seems to work pretty well. It is quite possible that on a scale very much smaller than what we are presently able to experimentally observe they are not actually point-like; in fact, this is the basic premise of String Theory, which treats elementary particles as vibrating strings on the order of the Planck scale.
We do not currently know what elementary particles really "are" on the most basic level, or even whether that question in itself has any physical meaning.

7. ZedFighter,

(double posting) my faust.

8. Originally Posted by ZedFighter
Originally Posted by Markus Hanke
Within the Standard Model all elementary particles are thought to be point-like ( ignore String Theory for the moment ), thus they cannot be subdivided into smaller parts.
Relative to the amount of knowledge yet to be gained, humans are still quite dumb. And for that reason I have so much difficulty wrapping my head around and truly understanding something like Point mass. I mean really, something can exist yet have no dimension... yeesh.
As Markus Hank has explained, elementary particles like electrons, neutrinos, and theoretical quarks, are mathematically treated like point particles according to the standard model. The most common statement is something like this: "Observations to date are consistent with electrons and neutrinos being point particles." There are a number of hypothesis that propose otherwise that you might find from search engines. As you might seem to suggest, present day theory may just be a stepping stone to the eventual understanding/realization of a "more logical" reality, or not

9. Originally Posted by ZedFighter
Relative to the amount of knowledge yet to be gained, humans are still quite dumb. And for that reason I have so much difficulty wrapping my head around and truly understanding something like Point mass. I mean really, something can exist yet have no dimension... yeesh.
If you really don't like the idea of point masses, you don't have to accept it. We do so because it is a mathematical convenience, validated as a good approximation well beyond the tiniest length scales currently accessible to experiment. For the electron, for example, experiments have placed an upper bound on its radius of something like 10E-20 m. Similarly, a neutrino's radius has been inferred from experiments to be something on the order of a Planck length.

String theory emerged in part from a dislike of point masses, so you're in good company. But to explain quantitatively all of the experimental data we have, the assumption of point masses in calculations yields excellent agreement with that data.

10. Those point masses are still split-able. They can be sub-divided into even smaller examples of what they are. In parametric down conversion, even a photon can be split, becoming two smaller (entangled) photons.

Spontaneous parametric down-conversion - Wikipedia, the free encyclopedia

There's also such a thing as a "heavy electron", implying that electrons may not always have to have uniform mass.

Heavy fermion - Wikipedia, the free encyclopedia

As for finding something smaller than a neutrino.... well... first we'd have to get to the point where we can actually work with neutrinos enough to manipulate them. About the best we can do now is produce them, and hope our detectors pick up a tiny few of them. When merely detecting them in the first place represents the state of the art, I can't imagine that we're going to be splitting them any time soon.

11. We have theorized some of the biggest things, like super titan Black Holes that keeps huge amounts of galaxies together no one really knows if it's Black Holes or other kinds of objects, but "there's something out there".

I belive in something smallter than point mass particles, like Super Strings. Point mass doesn't really explain all the oddities we experience on Quantum level, like things that can exist in 2 states or more, entanglements strange behaviours by responding at the same time in both ends to stimuli, etc.

12. I find it helpful to think of all objects of atomic size and smaller as "fuzzy little clouds" rather than "ball bearings" or "BB's". The visual image we think with contributes alot to what we are comfortable with. The cloud image keeps me from being troubled by questions about the physical dimensions of these particles. They are little cloud like entities that have qualities of charge, spin, polarity, mass and velocity. They have point mass, which I can visualize as the center of gravity of the little cloud.

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