If space and the universe is expanding, is the matter in it expanding too?

[pschroeter]

Don’t matter and the space it occupies expand together? I would think they are coupled together somehow. A lot of the explanations I have read about the Big Bang use the analogy of dots on a balloon being inflated to explain it. Well, actually the dots are expanding too. If both expand at the same rate you couldn’t tell everything is getting bigger.

[John37309]

Its a very good question! I want to know the answer too!

As space expands, do the individual atoms also expand?

My guess would be that the individual atoms DO NOT expand. But i would hazard a guess to say that the space inside a whole galaxy WOULD expand along with the rest of the universe. But its just my guess.

John.

[Geo Kaplan]

Don’t matter and the space it occupies expand together? I would think they are coupled together somehow. A lot of the explanations I have read about the Big Bang use the analogy of dots on a balloon being inflated to explain it. Well, actually the dots are expanding too. If both expand at the same rate you couldn’t tell everything is getting bigger.

Your last sentence is the key. Expansion is one thing, but forces within and between atoms are another, and you can't ignore those forces. We have to fix up the balloon analogy if you want to keep using it here: Don't think of matter as ink dots merely written on the balloon. Rather, think of them as, say, peanuts or something similar that have been glued on to the balloon. The forces keeping the peanut parts together are much stronger than those exerted by the stretching balloon. The peanut does expand because of the balloon, but by infinitesimal amounts.

[01101001]

Ned Wright: Frequently Asked Questions in Cosmology :: Why doesn't the Solar System expand if the whole Universe is expanding?

This question is best answered in the coordinate system where the galaxies change their positions. The galaxies are receding from us because they started out receding from us, and the force of gravity just causes an acceleration that causes them to slow down, or speed up in the case of an accelerating expansion. Planets are going around the Sun in fixed size orbits because they are bound to the Sun. Everything is just moving under the influence of Newton's laws (with very slight modifications due to relativity). [Illustration] For the technically minded, Cooperstock et al. computes that the influence of the cosmological expansion on the Earth's orbit around the Sun amounts to a growth by only one part in a septillion over the age of the Solar System. This effect is caused by the cosmological background density within the Solar System going down as the Universe expands, which may or may not happen depending on the nature of the dark matter. The mass loss of the Sun due to its luminosity and the Solar wind leads to a much larger [but still tiny] growth of the Earth's orbit which has nothing to do with the expansion of the Universe. Even on the much larger (million light year) scale of clusters of galaxies, the effect of the expansion of the Universe is 10 million times smaller than the gravitational binding of the cluster.

And it's worthwhile to read the other FAQ items, if you're just starting to wonder about cosmology.

[harkeppler]

The size of atoms is more ruled by the Heisenberg constant h (not to be confused with Hubble constant H), so atoms seem not to get larger.

The solar system is dominated by gravity, and, over the diameter of the solar system, cosmological expansion is neglectable small. Galaxies seem also to be "too small" to get larger under that influence.

If atoms would have been smaller in history, they light of far away galaxies should show effect of other wavelenghts in their spectra (lines!). If Earth would have been substantial smaller, continents would have fractured to much more smaller plates as a result of decreasing curvature of earth´s surface. A smaller solar system would also mean a nerar sun and more light. Earth should have been deadly hot.

[cosmocrazy]

Don’t matter and the space it occupies expand together? I would think they are coupled together somehow. A lot of the explanations I have read about the Big Bang use the analogy of dots on a balloon being inflated to explain it. Well, actually the dots are expanding too. If both expand at the same rate you couldn’t tell everything is getting bigger.

short answer yes.
but as its been explained in other posts this expansion is so small compared to the other forces, all the matter form atoms to stars within galaxies and groups of galaxy clusters are bound together by gravity in so that the expansion is un-measurable if any. Where the expansion is measured is at the far distant regions of our universe where clusters of galaxies that are observed to be moving away from each other at ever increasing rates. This is currently explained by the expansion of space.

[mugaliens]

No. While the effects of expansion permeate to the quantum level, even at the level of galactic clusters, gravitational forces override the effects of expansion, rendering the effects immaterial.

Think of expansion effects at the galactic level or less as a bug on the windshield of an SR-71.

[kevin1981]

From what i have read, the force gluing atoms and other sub atomic particles together is called the "strong force" and at tiny quantum scales it is very very very strong compared to the force of gravity.

[astromark]

The windscreen of a SR71 is strictly out of bounds for bugs. My mother ( A moth. ) told me... 'Stay away from those things'...

01101001 in post 4 said it all. The cosmic expansion would tear us asunder if it were not for atomic force and gravity.

The expansion of this solar system can be attributed to other forces. The ever weakening solar mass and lowering of density of the ether... ?

The actual reality is that any expansion is so little and slow that gravity simply overwhelms it. Orbital equilibrium continues.

As at a molecular level atomic forces prevail.

[Argos]

And remember that the inflating balloon is a desperately poor analogy.

[grant hutchison]

Ned Wright: Frequently Asked Questions in Cosmology :: Why doesn't the Solar System expand if the whole Universe is expanding?

See also Lineweaver and Davis's Scientific American article (480KB pdf); specifically the section beginning on page 43, entitled Is Brooklyn Expanding?

Grant Hutchison

[Jeff Root]

When I have described the balloon analogy in recent years, I have
covered the imaginary balloon with imaginary grease, then sprinkled
imaginary magnetized metal sequins onto the grease. The sequins
represent galaxies. As the balloon expands, the sequins naturally
remain constant size, and cluster together because of their mutual
magnetic attraction, sliding across the surface of the balloon.

Every analogy is flawed, but I think this version of the analogy fixes
some of the simpler flaws present in the actual balloon model that I
used in my high school speech class, nearly four decades ago. God!
Four decades! Oh my Oh my.... I think I'm gonna have a panic attack.

-- Jeff, in Minneapolis

[CaptainToonces]

When I have described the balloon analogy in recent years, I have
covered the imaginary balloon with imaginary grease, then sprinkled
imaginary magnetized metal sequins onto the grease. The sequins
represent galaxies. As the balloon expands, the sequins naturally
remain constant size, and cluster together because of their mutual
magnetic attraction, sliding across the surface of the balloon.

Every analogy is flawed, but I think this version of the analogy fixes
some of the simpler flaws present in the actual balloon model that I
used in my high school speech class, nearly four decades ago. God!
Four decades! Oh my Oh my.... I think I'm gonna have a panic attack.

-- Jeff, in Minneapolis

Are you saying that galaxies are attracted to each other by the magnetic/coulombic force? I thought those charges evened out on that scale and it was only gravity that came into play?

[Strange]

When I have described the balloon analogy in recent years, I have
covered the imaginary balloon with imaginary grease, then sprinkled
imaginary magnetized metal sequins onto the grease.

I like it.

Are you saying that galaxies are attracted to each other by the magnetic/coulombic force? I thought those charges evened out on that scale and it was only gravity that came into play?

It's an analogy. The (surface of the) ballon is an analogy for the universe, magnetism is an analogy for gravity and the grease is an analogy for ... uhm ... cosmic hair products.

[Jeff Root]

Okay, that's a good antidote to my panic attack. What is the
grease analogous to??? Hmmmm..... Hmmmmm.....

Actually, besides making the sequins stick to the balloon, the
grease compensates for the facts that magnetism is a much
stronger force than gravity and falls off in strength in proportion
to the cube of the distance, rather than the square; the sequins
are much closer together than galaxies, and the sequins are far
less massive than galaxies (so their inertia is far less).

-- Jeff, in Minneapolis

[pzkpfw]

When I have described the balloon analogy in recent years, I have
covered the imaginary balloon with imaginary grease, then sprinkled
imaginary magnetized metal sequins onto the grease. The sequins
represent galaxies. As the balloon expands, the sequins naturally
remain constant size, and cluster together because of their mutual
magnetic attraction, sliding across the surface of the balloon.

I like ants. The balloon expanding spreads their legs a bit, but they don't (yet) get pulled to bits.

(
Also, because the ants walk around a bit, sometimes "attracted" to each other - it shows that some get closer while most overall get further away (red/blue shift).

And, while the ants have a maximum "ant speed" - some get further from each other faster than ant speed - because the balloon itself expands (things don't move faster than c, but...).
)

But overall, yeah, nobody should take analogies too far.

[cosmocrazy]

I like ants. The balloon expanding spreads their legs a bit, but they don't (yet) get pulled to bits.

(
Also, because the ants walk around a bit, sometimes "attracted" to each other - it shows that some get closer while most overall get further away (red/blue shift).

And, while the ants have a maximum "ant speed" - some get further from each other faster than ant speed - because the balloon itself expands (things don't move faster than c, but...).
)

But overall, yeah, nobody should take analogies too far.

I like this analogy! its simple and easy to visualise.

I often feel like an ant, the world is rushing by under my feet and i don't know what direction to go in.

[mugaliens]

Okay, that's a good antidote to my panic attack. What is the
grease analogous to??? Hmmmm..... Hmmmmm.....

Inertia.

[Infinitenight2093]

quick answer: No because gravity keeps clumped matter together while the "space between" expands

[Jeff Root]

I'll reply to the original question, too.

The cause of the acceleration of the expansion is unknown.
So its mechanics are unknown. In particular, it is unknown
whether "space itself" (whatever that means) is expanding,
or there is an actual "force" pushing matter apart, or what.
So it is unknown whether there is any effect at all on the scale
of galaxies, solar systems, planets, people, or particles. Even
effects that are way, way too small to measure. We only know
that it is measureable on the scale of well-separated clusters
of galaxies.

-- Jeff, in Minneapolis

[tommac]

Depends on what is causing the expansion. Also it may depend on the observer. If the expansion is from SR or GR then a distant observer should would see matter in that space expand also right? But just from the relativistic effects .... in other words it wouldn't be proportional to the expansion of the universe.

[galacsi]

I'll reply to the original question, too.

The cause of the acceleration of the expansion is unknown.
So its mechanics are unknown. In particular, it is unknown
whether "space itself" (whatever that means) is expanding,
or there is an actual "force" pushing matter apart, or what.
So it is unknown whether there is any effect at all on the scale
of galaxies, solar systems, planets, people, or particles. Even
effects that are way, way too small to measure. We only know
that it is measureable on the scale of well-separated clusters
of galaxies.

-- Jeff, in Minneapolis

Jeff , that's the more acceptable answer I have seen on the subject !

[kevin1981]

When we look out to the furtherest regions of the universe everything is expanding away from us near to the speed of light, so from there point of view so are we. So are we traveling near light speed but don't realize because all the "near by" clusters are moving with us ?

[Jeff Root]

Speed is relative.

-- Jeff, in Minneapolis

[kevin1981]

Speed is relative.

Which means what? Relative to the observer? Does that mean we are traveling through space at a non relativistic speed but others far away see as traveling at near the speed of light. But if i was one of the others i would also be traveling at a non relativistic speed ?

[Shaula]

Which means what? Relative to the observer? Does that mean we are traveling through space at a non relativistic speed but others far away see as traveling at near the speed of light. But if i was one of the others i would also be traveling at a non relativistic speed ?

It means that the concept of us moving is incomplete - we have to add in relative to what. "I am travelling at 10m/s" is meaningless unless you have a reference object. What you should say is "I am travelling at 10m/s relative to the Earth's surface". There is no absolute space frame of reference we can use to define a universal speed - it always has to be relative to something else.

[kevin1981]

Because space is empty we have no reference frame to measure our speed against, if that what you mean ?

So they see us moving near speed of light but we ourselves can not measure it against anything so we don't feel like we are moving ?

[Shaula]

Because space is empty we have no reference frame to measure our speed against, if that what you mean ?
So they see us moving near speed of light but we ourselves can not measure it against anything so we don't feel like we are moving ?

Sort of - one of the important aspects of relativity is the idea that the laws of physics are invariant at different speeds. So there is no experiment I can perform to determine what speed I am moving at unless I rope in something else to measure my speed relative to. What it basically comes down to is that it is not a gap in our ability to measure our speed - our speed simply cannot be measured against an absolute still background everyone agrees on, because there is not one. So they can look at us and say we are travelling at lightspeed and they are sat still, we can look at them and say that they are travelling at lightspeed and we are sat still. Both viewpoints are correct in a sense. They are just different ways of expressing the same underlying truth - that we are each moving at lightspeed relative to each other.

Relativity can make the brain squeak at first - it is one of those subjects that has so many subtle effects and ramifications that very clever people still get the wrong end of the stick trying to understand it. That is basically because it is a very mathematical theory and to really get it you have to read and do the maths. Descriptive approximations to it can give you an idea what is going on but don't really join it up into the beautiful theory it is. FWIW I haven't done much of it - I an pig ignorant compared to some of the people on here so hopefully one of them can do a better job than me at explaining it!

[noncryptic]

I find expansion more easily understood as being the result of a (rather weak) force, because then it follows that this force can be counteracted by other forces (gravity, atomic forces).

[Strange]

Because space is empty we have no reference frame to measure our speed against, if that what you mean ?

We can measure our velocity relative to galxies near or far (and get a different answer in each case).

So they see us moving near speed of light but we ourselves can not measure it against anything so we don't feel like we are moving ?

Perhaps it would be more accurate to say that if you cannot measure it against anything, then you are not moving (rather than not feel like you are moving).

The simplest thing for us is to consider ourselves stationary and all other galaxies moving at some relative speed away (usually) from us. But it would be just as real to select some other galaxy and say that one is stationary and we (and everything else) and moving relative to it.

You still wouldn't be able to feel it though; for the same reason you can't feel your ~1,000MPH rotation round the earth.