is thier a limit to how small or big something can be?

[Falloutboy]

What I mean is do you think thier is a certain partical that cannot be divided in a smaller partical? and in the same line of thinking is the universe as we know it the biggest thing or could it be one of many universes. (not other demensions but other universes out side of our own) which in turn are part of something bigger and so on. for all we know it the universe as we know it could be a partical in another universe

 

[f95toli]

As far as we know certain particles, such as the electron, are point-like and have no size at all ("the diameter is zero"), you can't make anything smaller than that.
Physicaly the largerst size is the size of our univserse, even if one of the multiverse theories are correct the maximum size is limited since nothing can exist in several universe at the same time (dy definition).

 

[The J]

I read in Wired magazine that there is a theoretical limit because the laws of quantum mechanic are unable to tell the difference from here or there at a certain point. I don't remember what that limit is, unfortunately.

 

[f95toli]

There is no such limit in quantum mechanics, what you are describing is the wave-particled duality but that is applicable to everything (even to you); the effects oft this duality are just much stronger for small particles.

 

[imported_jb]

<unscientific>i planned to beleive that our universe is a closed string that is currently still expanding (like living inside an round lightining bolt). with that being a membrane i guess. hmmm,.... i want to say that a string is a proton/neutron... maybe not electron, and the universe started as hydrogen (2 universes maybe) then maybe hydrogen what, 4 universes?.... whatever.. i just got up.</unscientific>

 

[GMElias]

Originally posted by: f95toli
There is no such limit in quantum mechanics, what you are describing is the wave-particled duality but that is applicable to everything (even to you); the effects oft this duality are just much stronger for small particles.

there is quantum mechanics...although hopefully and eventually (though not sure about it) there will be a GUT (Grand Unified Theory) which will incorporate quantum with relativity. WRT smallest particles, that would be the quark. In fact, there are different "flavors" of quarks (why they call the different kinds flavors, I forgot!)...anyhow, they realte to spin, etc. Electrons are point-like particles with no mass, only charge/spin (remember boson, mesons, etc. also have no "mass" as we define it, but they have different spins from electrons, such as non-integer spins).

Anyway, there is really no limit to how large something can be because the Universe is "infintely" large and expanding. Don't ask me how you can be infintely large and still growing larger...then again, i think the matter stays the same...just gets spread out more...also, keep in mind that the lim(x->0) Infinity +1 is greater than lim(x->0) 1+infinity...because infinity does not have the properties of integers (ie...1+2=2+1...not so with infinity). So, maybe infinity can indeed grow larger.

Anyway, just some food for thought...I studied this stuff a long time ago, so I don't remember all the details. read some Stephen Hawking for fun.

-Elias

 

[silverpig]

Originally posted by: f95toli
There is no such limit in quantum mechanics, what you are describing is the wave-particled duality but that is applicable to everything (even to you); the effects oft this duality are just much stronger for small particles.

There kind of is. It's the Planck length. I think it's the distance light travels in the planck time or something. Just off the top of my head.


Yeah it seems I was right:

Question

What is Planck length? What is Planck time?

Asked by: Adam Faust

Answer

The Planck length is the scale at which classical ideas about gravity and space-time cease to be valid, and quantum effects dominate. This is the ?quantum of length?, the smallest measurement of length with any meaning.

And roughly equal to 1.6 x 10-35 m or about 10-20 times the size of a proton.

The Planck time is the time it would take a photon travelling at the speed of light to across a distance equal to the Planck length. This is the ?quantum of time?, the smallest measurement of time that has any meaning, and is equal to 10-43 seconds. No smaller division of time has any meaning. With in the framework of the laws of physics as we understand them today, we can say only that the universe came into existence when it already had an age of 10-43 seconds.

 

[f95toli]

The electron definitly has a mass, it is 9.1904e-31 if I remember correctly.
All "normal" particles have mass with the exception of the photon (and maybe a few others).

And I can't really see what spin has to do with this?

 

[Chaotic42]

AFAIK the smallest that something can be is the plank length, 10^-35 meters. It's the smallest space that has any meaning.

I would guess (in a very non-professional manner), that the largest that something can be would be determined by its mass. If it got too large, it would collapse in on itself.

 

[silverpig]

Originally posted by: GMElias

Originally posted by: f95toli
There is no such limit in quantum mechanics, what you are describing is the wave-particled duality but that is applicable to everything (even to you); the effects oft this duality are just much stronger for small particles.

there is quantum mechanics...although hopefully and eventually (though not sure about it) there will be a GUT (Grand Unified Theory) which will incorporate quantum with relativity. WRT smallest particles, that would be the quark. In fact, there are different "flavors" of quarks (why they call the different kinds flavors, I forgot!)...anyhow, they realte to spin, etc. Electrons are point-like particles with no mass, only charge/spin (remember boson, mesons, etc. also have no "mass" as we define it, but they have different spins from electrons, such as non-integer spins).

Anyway, there is really no limit to how large something can be because the Universe is "infintely" large and expanding. Don't ask me how you can be infintely large and still growing larger...then again, i think the matter stays the same...just gets spread out more...also, keep in mind that the lim(x->0) Infinity +1 is greater than lim(x->0) 1+infinity...because infinity does not have the properties of integers (ie...1+2=2+1...not so with infinity). So, maybe infinity can indeed grow larger.

Anyway, just some food for thought...I studied this stuff a long time ago, so I don't remember all the details. read some Stephen Hawking for fun.

-Elias

Uh, you got that mostly wrong. Electrons are (so far as we know) point particles WITH mass. They are fermions with spin 1/2.

Fermions are particles with 1/2 integer spin.

Bosons are particles with integer spin (0 included).

Leptons are the electron, muon, and tau particle and their associated anti particles (and neutrinos and anti eutrinos too I think). They are fermions.

Mesons are particles consisting of a quark-antiquark pair bound by a gluon and an antigluon. They have spin and mass.

Hadrons are bound states of 3 quarks. They have mass and spin. Examples are protons and neutrons.

As for quarks being the smallest, that's not really true either. Quarks are relatively heavy compared to electrons. In fact, the top quark has a mass greater than that of a gold nucleus. Of course, as far as size goes, no one really knows how wide a quark is because they can't be isolated (you'll never see a quark float by).

 

[Blackjack2000]

IMO the answer to both questions is no. The universe is not necessarily expanding; only the observable universe is expanding, and it expands in all directions at the speed of light. (Imagine if the big bang happened today. In one year the observable universe would be one light year in all directions.)

as far as how small something can be, the "strings" in string theory are about Plank length, and even they can be "cut" if a tremendous amount of energy is applied.

Please feel free to correct me, as I'm no astronomist...

 

[Matthias99]

Originally posted by: GMElias
also, keep in mind that the lim(x->0) Infinity +1 is greater than lim(x->0) 1+infinity...because infinity does not have the properties of integers (ie...1+2=2+1...not so with infinity). So, maybe infinity can indeed grow larger.

This is incorrect. The cardinality of an infinite set does not change, no matter how many items you add to it (that being part of the definition of an infinite set). For example (although this seems counterintuitive), the size of the set of all odd integers is the same as the size of the set of all integers. Also, there are an equal number of integers and real numbers, even though there are infinitely more real numbers in any bounded part of the number line than there are integers in that same part of the number line (reals are "uncountably infinite", whereas integers are not, but both sets are infinite in size). Things get all wacky in math when you start throwing around infinity.

This may not relate to the size of the universe and whether or not it is unbounded, however. I'm just talking about the mathematical definitions of infinity.

 

[Mday]

universe > object > photon

that's about it

 

[CycloWizard]

Official Superstring Theory Site

Superstring theory purports that everything is made of of infinitesimal 'strings'. I can't recall the intimate details of the theory, but many believe that it is the unifying theory of physics. It has been mathematically proven, with one catch: it requires the existence of additional dimensions. Seems like a big catch, but many physicists don't think so. The question becomes whether or not we can actually perceive these other dimensions to test the theory.

It's been quite a while since I learned about this, so I can't recall the alleged 'length' of these strings, but they were, for all intents and purposes, infinitely small.