# What really is the smallest “mass” or “object” in the universe?

As the Wikipedia article Subatomic particles shows, with respect to the sciences, the atom is obviously not the smallest piece of mass. Apparently, if people have already broken down the atom in to particles smaller than so, why haven't particles been understood yet?

Old scholars reasoned that everything has smaller parts, so what's smaller than subatomic particles?

Or is there a limit in the size of mass, only being able to be small to an extent?

Because mass always seems to keep growing in new fundamental particles discovries, (as the Higgs), but when scaling opposite in size, we reach a limit. Therefore, big always gets bigger, but why does small have limits?.

• 'mass always seems to keep growing' - really? Please explain. – Rory Alsop Sep 21 '13 at 21:30
• Related: physics.stackexchange.com/q/41676/2451 and links therein. – Qmechanic Sep 22 '13 at 9:19
• This is a fine question until 'mass keeps growing': consider revising that bit... I've never heard of such a thing. – anon01 Apr 22 '16 at 4:02
• "why does smaller have limits" is not answerable by physics theories, and can only be bounded by observations/experiment. Physics does not answer "why"questions, only "how" , using mathematical models, causal connections of observations are best described . – anna v Apr 22 '16 at 4:33
• Possibly the comment may refer to gravity, when two bodies coalesce they are able to attract more bodies. – jim Apr 22 '16 at 20:38

It is important to note that elementary particles are-at least in normal quantum field theories like the Standard Model-treated as point particles, with NO internal structure or spatial dimensions.

String theory, however, does assign structure to the fundamental building blocks of our universe. These are tiny, with dimensions on the order of the Planck length, around $10^{-35}$ meter. These strings are hypothesized to explain all fundamental particles, giving an alternative solution to your question.

If we work on the theory that over decades we have been able to with the assistance of more unique scopes been able to break down these sub atomic particles then in theory, as we have in discovering quarks, these particles must be made up of even smaller particles. Our perception is only confronted by our current knowledge and capabilities, therefore in say 100 years we may find our universe is turned inside out that small is as significant as large and there are no boundaries.

Fundamental values are quantised so I believe there is a 'minimum' or 'smallest' mass. If you look at the similarities between fundamental electromagnetic and gravitational interactions then its clear to see the two are very similar, with gravitational interactions being related to Mass and EM related to Charge. There is a minimum quantised Charge (e, or 1.6x10^-19) so why can't there be a quantised mass. (NB: I know quarks have charges that are fractions of e but as far as we know they don't exist on their own) It may be the case that we simply have not yet found a particle with the lowest quantised mass. Or possibly the electron is the most 'fundamental' of all particles with it's mass being the smallest mass there is (Can anyone think of anything smaller than an electron?) EDIT: I think neutrinos have mass, most likely smaller than an electrons, possibly they have the smallest mass.

• When you feel the need to use phrases such as "I believe" , "It may be the case", "Or possibly", and "I think" to preface every statement in your answer, that is an indication that you should let someone more informed write the answer in question. The guidelines which pop up on this site when you go to write your first answer state as much. – Duncan Harris Apr 23 '16 at 0:08

I guess the smallest mass would be the neutrino's, though their mass hasn't technically been determined, but it is thought to be of the order 0.05 eV.

Mass so small that it cannot be observed, measured, tested, is unknown, but believed to exist, is not mass. it is pre-mass. It is alpha. The substance and evidence is confirmed only by our strong, unwavering belief that all things visible are made of things not visible.

• Whoa. Alpha pre-mass. -1 – Brandon Enright Mar 1 '14 at 0:17
• Total nonsense. – Diracology Apr 22 '16 at 0:10
• @CheshireCat First time I see swearing on SE. Still, quite on topic. – Giorgio Comitini Apr 22 '16 at 21:11
• i would claim it is kappa, not alpha. Kappa. – Wolpertinger Apr 22 '16 at 22:21