Atoms, Empty Space and the Universe.

[YT2095]

I`ve read quite a few times on here that the Universe is expanding from no particular point, but from ANY 2 points one may care to mention.

 

then we have the Atom with it`s Nucleus and surrounding Electrons, Most of the atom is in fact "Empty Space".

 

so are Atoms also increasing in Size too or rather "Expanding"?

[J.C.MacSwell]

I`ve read quite a few times on here that the Universe is expanding from no particular point' date=' but from ANY 2 points one may care to mention.

 

then we have the Atom with it`s Nucleus and surrounding Electrons, Most of the atom is in fact "Empty Space".

 

so are Atoms also increasing in Size too or rather "Expanding"?[/quote']

 

If they were (proportionally) would we know that space is expanding at all?

 

The expansion may effect their stability somewhat, positively or negatively depending on the atom but I think their size would remain unchanged.

[YT2095]

If they were (proportionally) would we know that space is expanding at all?

 

agreed, and that would certainly make the basis for a philosophical debate.

 

I`m interested in the space between parts of an Atom, what is it? a vacuum maybe?

and is it subject to the same expansion that the Universe is undergoing?

if it isn`t, at what point does this expansion cease or not have any effect upon?

[J.C.MacSwell]

agreed' date=' and that would certainly make the basis for a philosophical debate.

 

I`m interested in the space between parts of an Atom, what is it? a vacuum maybe?

and is it subject to the same expansion that the Universe is undergoing?

if it isn`t, at what point does this expansion cease or not have any effect upon?[/quote']

 

Isn't this where quantum theory/guesswork/uncertainty takes over and noone knows?

 

Could this be where the expansion is generated?

[YT2095]

Isn't this where quantum theory/guesswork/uncertainty takes over and noone knows?

 

Could this be where the expansion is generated?

 

LOL, at the risk of sounding overly Blunt, If I KNEW that, I wouldn`t be asking would I?

[J.C.MacSwell]

LOL, at the risk of sounding overly Blunt, If I KNEW that, I wouldn`t be asking would I?

 

Just thoughts on the subject. The question marks are mostly so noone takes them as definite or accepted theory. I was hoping others might respond also.

[YT2095]

Could this be where the expansion is generated?

 

although I can`t answer my own question, My Guess would be no it isn`t.

if it Were, then the instrumentation we use to know that the universe is expanding wouldn`t be able to detect this (I don`t know how they know this anyway, but I summise they use equipment).

 

just a thought

[Martin]

YT, MacSwell, not being an authority (understatement) I just take the word of mainstream working cosmologists about this---they could be wrong of course and some different model of the universe could come into favor, but I dont worry about that possibility---and here's the impression I get.

 

the present rate of expansion as a yearly percentage is very small and has no effect on anything from the size of an atom to a galaxy

 

these things (atoms, galaxies) are "bound systems" that are held together and can cope with a little gradual expansion. something like the solar system ADAPTS to expansion by reaching a stable size which is just a tiny bit larger than it would be without expansion and then it stays that size---the expansion is balanced by the tendency of it to fall together.

 

even CLUSTERS OF GALAXIES are mostly "stable bound systems" and are not going to be pulled apart as long as expansion is this slow. but I suppose there have been marginal cases of bound structures that got dispersed and some will in the future. The main thing is that (1) expansion is so slow and (2) the gradual acceleration of expansion is so much slower still, that one can mostly ignore it. Your coffee cup, your galaxy, your meterstick or ruler are not affected.

 

People speculate about imagined futures where expansion would increase so much that things we consider stably bound would come unbound but that is based on hypotheses about eventual acceleration that we can't check now so it is fantasy about the way future.

 

But on much larger scale, distances between things that are not gravitationally bound DO ACTUALLY INCREASE. And that is very interesting and worth trying to comprehend.

 

I will try to write a post about that, unless severian or someone does it before I get around to it. But the first thing to grasp is that even though it is very interesting it does not affect atoms or galaxies or any familiar object. Only the distances between galaxies and even then only galaxies that are very far away and not part of our local grouping or cluster. (Andromeda as you may have heard is getting closer, it is part of our local group)

[DQW]

deleted

[YT2095]

I`m kinda with ya when you mention "Bound systems", from a Chemists viewpoint the Atom is sacrasanct(sp?) although the "Empty Space" in it is never really addressed, it`s certainly the domain of Physics and probably a specialised field at that.

 

so from what I can glean so far, effects on either Strong or weak nuclear forces don`t apply?

but I do find it hard to imagine a "Place" in the Universe where Gravitational forces Don`t exist to some degree?

[Martin]

the annual fraction space expands is about ONE THIRTEENBILLIONTH

and by billion I mean E9 or e9 or 10^9 or 1000000000.

and it is actually around 13.8 so maybe I should say a fourteenbillionth

forget accuracy, it is just a nuisance. 13 or 14 what does it matter.

 

 

distances expand that much every year.

 

So if some galaxy is a billion LY away at this moment, then this time next year the distance to it will be increased by 1/13 LIGHTYEAR.

 

the annual increase in distance is equal to the distance divided by 13 billion. so you take a billion (the distance) and divide by 13 billion, and you get 1/13 of a lightyear. this is almost nothing when you look at it as a fractional increase.

 

What people actually seem to get all worked up about is not the actual increase in distance but how do you PICTURE IT IN YOUR HEAD.

How do you picture a world in which distances increase at some regular rate, even between things that are standing still. the expansion of space is not the things (distant galaxies) moving away from us, it is the fact that the METRIC FUNCTION OF THE UNIVERSE the distance measure tool that cosmologists use and that has been found to work, the socalled "FRW metric", is actually time dependent and has a built in rate of expansion (which is even very slowly increasing but that is a separate issue)

 

SO IF YOU HAVE TWO THINGS THAT ARE SITTING STILL AND YOU COME BACK AND MEASURE next year with the same FRW metric THEY WILL BE FARTHER APART.

 

this seems to be what puzzles everybody because it is different from what you learn in school as a child. It contradicts what we are taught in school that distance measures are not timedependent and distance stays the same.

[YT2095]

I`ve no problem with that at all, I can`t say I can exactly "Picture it" but I can see what`s happening theoreticaly

 

of course what makes the "picture" so much more interesting is that even though a 1/13 or 14`th of a billion per annum (I`m taking that as an earth year), considering measurements and times are often quoted in Billions of years with the universe, that`s still then becomes a significant increase

 

take the 2 objects on the table you mentioned (ignoring Reality for a second) a Billion years ago they Would have been much closer, measurably so with even a household rule or tape measure, what of the Atoms? did the same happen to them? and by extension, have objects become Larger (as movement appart is just that, and would/should effect a single item also).

[Martin]

hello YT.

I didnt see your post just now when I wrote this, and it does not respond to your question. If two things on table maybe 13 cm apart, what is a 13billionth of that----a billionth of a cm. Hmmm. I see your point so if you wait a billion years then (except for the fact that the things are bound) they would change distance by 1/13 cm.

 

yes that is right. but the atoms in the tabletop are bound by chemical bonds and do not change separation, so the table stays the same size. and the two objects are bound to the tabletop by FRICTION which is very gentle chemical bonds as well plus the bumpiness of the table combined with gravity holding the objects essentially LOCKED IN PLACE. even in this kind of idealized situation of watching a table for a billion years, you do NOT see the ojbects get 1/13 cm further apart. too bad.

 

bound systems stay the same size

 

======rest of post I wrote earlier======

so here is the terrifying contradiction, we are meeting it headon.

 

1. the only theory of gravity and spacetime that we have so far that checks out with observation is einstein 1915 Gen Rel.

 

it fits with all the data about neutron stars and the atomic clocks in the GPS satellites and lightrays bending as they pass the sun and the Microwave Background and where Newton is precise enough it says the same as Newton. so this is a tremendously successful theory that we dont yet have any good alternative replacement for. we have to accept it!

 

2. Gen Rel is ABOUT METRICS. it is about the geometry of spacetime and that geometry is represented, in the theory, by the DISTANCE TOOL that tells the distance between any two points, and from that you can deduce all the geometry: angles, areas, volumes etc.

Gen Rel is essentially AN EQUATION WHICH THE METRIC HAS TO SATISFY. it is an equation relating the metric, the universe distance function, to the matter in the universe, and it explains why the metric function defined on spacetime has to be what it is. The metric has to be a solution of the Einstein equation, the basic Gen Rel equation.

 

3. the flabberghasting thing about this, now, is that practically the only solutions to the Einstein equation are metrics which are time dependent! where distances are either slowly increasing (like in our universe) or slowly decreasing, or the same thing but fast, in any case changing.

 

there are some stready-distance solutions but they are tricky and easily come unglued, or they need special unrealistic assumptions. people used to toy with these static solutions I guess but they dont anymore.

 

To summarize:

Gen Rel is the only thing we know that works. It is a theory of distance functions. We have to accept it at least for the time being. According to Gen Rel it is natural for distance functions to be time dependent---to increase or decrease. In our universe the distance function (goes by name of FRW metric) happens to be increasing. therefore the distance, measured in constant units whether LY or cm, between widely separated objects that are sitting still will gradually get bigger

 

there are some good Sci Am links about this----an article by charles Lineweaver and Tamara Davis. they are around here somewhere

[Martin]

EDIT : Seeing that Martin has chimed in, I shall advise that my post be ignored in favor of his...especially, if we're saying things that are at odds with each other.

 

Hi DQW, I just saw your post, too busy writing to see it before.

I was going to advise that my post be ignored in favor of yours but you beat me in courtesy. cant claim anything more than layman familiarity with this fascinating stuff. Glad you are on hand. Let's advise YT to ignore us both or neither

[YT2095]

Awww he deleted it

 

I`de have enjoyed reading that, atm it`s all just food for thought and anything on this topic put in "Laymans terms" will be ideal for me anyway!

it`s not exactly my Favorite area of Science either, but occasionaly I Do get questions that require SOME SORT or resolution

[herme3]

agreed' date=' and that would certainly make the basis for a philosophical debate.

 

I`m interested in the space between parts of an Atom, what is it? a vacuum maybe?

and is it subject to the same expansion that the Universe is undergoing?

if it isn`t, at what point does this expansion cease or not have any effect upon?[/quote']

 

Those are some very good questions that I have wondered about. Most people would probably say that space between the parts of an atom is a vacuum. They are probably right, because I really don't know very much about atoms or subatomic particles.

 

However, I believe that the space between parts of an atom could be a type of subatomic particle that we don't know about. Perhaps instead of forces holding matter together, there are very small particles between other particles that keep them from falling apart. These new subatomic particles could be so small and compacted together that they can fit between any other type of particle in the universe. Anytime there is a type of "empty space" these new particles fill in the space. That is just a theory I thought of. I have no evidence that could prove it. Do you think I should create a new thread about my theory, or do you think the existence of these particles is impossible?

[ydoaPs]

That is just a theory[/b'] I thought of.

I have no evidence that could prove it.

aren't you contradicting yourself there?

Do you think I should create a new thread about my theory

for the sake of everyone's sanity, don't

[DQW]

I'm only glad to yield the floor to those who are better informed.

 

For now, I'd like to address one little question that YT asked :

 

I`m interested in the space between parts of an Atom, what is it? a vacuum maybe?

I'd rather let Martin handle this, but perhaps I can start something off, at least.

 

YT : According to the standard model "everything is a vacuum" ! While that was worded thusly for effect, it is hardly untruthful. All matter is currently believed to be composed of fundamental particles (leptons, quarks) which are pointlike - they are 0-dimensional objects. So, essentially everything is just composed of these points and all else is just "the space between". So, given a certain volume of space, the probability that any randomly chosen point will contain matter is 0.

 

This view no longer holds if you choose to view the mass being distributed, not in sharply peaked delta-"functions", but instead as scaled by the probability density.

 

And when you ask if it is a 'vacuum' you might want to clarify what exactly you mean by that word.

[Cap'n Refsmmat]

However, I believe that the space between parts of an atom could be a type of subatomic particle that we don't know about. Perhaps instead of forces holding matter together, there are very small particles between other particles that keep them from falling apart. These new subatomic particles could be so small and compacted together that they can fit between any other type of particle in the universe. Anytime there is a type of "empty space" these new particles fill in the space. That is just a theory I thought of. I have no evidence that could prove it. Do you think I should create a new thread about my theory, or do you think the existence of these particles is impossible?

Ever heard of "gluons?" That's what are supposed to be holding atoms together.

 

Except for the "empty space" and filling in part.

[herme3]

Ever heard of "gluons?" That's what are supposed to be holding atoms together.

 

Except for the "empty space" and filling in part.

 

Isn't atomic structure still unknown for the most part? I don't believe that scientists have ever been able to see an atom with a microscope. Would that even be possible? However' date=' how do we know that empty space is completely empty? What if the particles are just so small that we can't detect them with our current technology?

 

aren't you contradicting yourself there?

 

No, I just wanted to make it clear that I can't think of a way to prove it. It just seems like creative idea. Maybe I should create a new thread about this. I don't want to bring YT2095's thread off topic.

[ydoaPs]

No, I just wanted to make it clear that I can't think of a way to prove it. It just seems like creative idea. Maybe I should create a new thread about this. I don't want to bring YT2095's thread off topic.

no proof=no theory

[herme3]

no proof=no theory

 

I'm sorry. I meant to say that I have an idea.

[DQW]

Isn't atomic structure still unknown for the most part?

No.

 

I don't believe that scientists have ever been able to see an atom with a microscope.

Wrong again. Take a look at the STM Gallery at the website of IBM (Almaden) Labs. Not only have scientists looked at individual atoms, they have picked them up one by one and moved them around (into different shapes) to draw funny pictures and write words.

 

Oh, scientists have also looked at individual electrons, by the way. Look into the MRFM measurement of a single electron spin by Rugar et al (sometime in the summer of last year).

 

Would that even be possible?

Not only is it possible, it's history.

 

However, how do we know that empty space is completely empty?

Empty of what ?

 

What if the particles are just so small that we can't detect them with our current technology?

It depends on what these particles are doing. If they are doing something important, it is quite surprising that we understand (and can predict) atomic properties so incredibly well without considering such particles. Also, something being small has ABSOLUTELY NOTHING to do with our ability to detect it. We have detected particles with ZERO size. What can be smaller ?

[DQW]

http://www.almaden.ibm.com/vis/stm/gallery.html

 

Xenon atoms on Nickel substrate :

 

Iron atoms on Copper (a Quantum Corral) :

 

 

Single Electron Spin measurement by Rugar et al, IBM-Almaden

http://www.almaden.ibm.com/st/nanoscale_science/asms/mrfm/

 

The Nature article :

http://domino.research.ibm.com/comm/pr.nsf/pages/rscd.nanoscale-picb.html/$FILE/single%20spin%20MRFM%20Nature%20article.pdf

[DQW]

Sorry for the digression. I think we should get back to YT's questions on expansion.