Universal Expansion: Is All Matter Expanding?

[Landrew]

If a little knowledge is a confusing thing, I certainly have the prerequisites to be confused about Universal Expansion. Some physicists seem to be saying that all the stars and galaxies are flying apart like shrapnel from a large explosion, and other physicists seem to be saying that space itself is expanding metrically, thereby accounting for the fact that the more distant the object we observe, the faster it seems to be moving away, even apparently exceeding the speed of light.

If space itself is expanding over time, then matter itself would have to be expanding at the same rate, otherwise the Earth wouldn't have remained in the "Goldilocks Zone" which has allowed life to exist in this planet for billions of years.

So, if the metric expansion model is correct, millions of years ago, our solar system was a smaller scale model of how it is now. If our Earth was indeed smaller, the gravity of our planet would have also been less. The flying dinosaurs would have had less difficulty flying in lesser gravity. Perhaps this explains why when scientists examined their skeletons, they determined that they were built much too heavy to ever get off the ground today.

Too weird to consider? Or is a better solution to invent a theory that 96% of our universe is invisible dark matter, to make things seem to work out?

 

[russ_watters]

Not correct: the expansion only happens in the large scale.

 

[Landrew]

Not correct: the expansion only happens in the large scale.

What makes us exempt, and what is the evidence?

 

[Vagn]

The effect gravity has on spacetime appears to prevent small scale expansion. The evidence is that local bodies are not moving away from us, we aren't moving further away from the galactic core, and the Milky Way is not moving away from other galaxies in the local cluster and so on.

 

[Landrew]

The effect gravity has on spacetime appears to prevent small scale expansion. The evidence is that local bodies are not moving away from us, we aren't moving further away from the galactic core, and the Milky Way is not moving away from other galaxies in the local cluster and so on.

But if matter and space were expanding equally together, how would we know?

 

[Kracatoan]

The best way to sort this out is to look at it form the other way round, if stuff is expanding now, it must have once been in a single point, where all the particles were overlapping, and accoridng to Pauli's exclusion principle, only Bosons can do this, not fermions which make up matter. This means that the bosonic bit of the universe is gettng bigger, because that is allowed,but the fermionic bit isn't allowed, so matter stays the same size.

Yes, I know matter also came form the same single point, but actually at the start it was all bosons, which then "decayed" and formed matter, in a round-a-bout, messy sort of way.

 

[Landrew]

Not correct: the expansion only happens in the large scale.

Is that really possible?

 

[hadsed]

Yes because the effects of gravity at that range are much stronger than the dark energy (if you want to call it that) force that is 'expanding' the universe. That's why galaxies don't just get bigger or anything like that, but we know it's happening because the galaxies themselves are flying away from us (accelerating in fact).

 

[Landrew]

Yes because the effects of gravity at that range are much stronger than the dark energy (if you want to call it that) force that is 'expanding' the universe. That's why galaxies don't just get bigger or anything like that, but we know it's happening because the galaxies themselves are flying away from us (accelerating in fact).

Either that, or the larger space-time matrix becomes, the larger the distances become over time as a function of fractional expansion.

 

[hadsed]

What do you mean fractional expansion?

 

[Landrew]

What do you mean fractional expansion?

I mean the whole of space-time expanding as a unit, by a percentage or a fraction over time.

 

[Chronos]

Do the math. Landrew. You are assuming facts not in evidence. If you test your assumptions against Einstein's elliptical transforms, your error will be obvious.

 

[Landrew]

Do the math. Landrew. You are assuming facts not in evidence. If you test your assumptions against Einstein's elliptical transforms, your error will be obvious.

I'm not assuming or asserting anything. I'm just asking questions. If you don't have the answers, insulting won't make you smarter.

 

[Michel_vdg]

So, if the metric expansion model is correct, millions of years ago, our solar system was a smaller scale model of how it is now. If our Earth was indeed smaller, the gravity of our planet would have also been less. The flying dinosaurs would have had less difficulty flying in lesser gravity. Perhaps this explains why when scientists examined their skeletons, they determined that they were built much too heavy to ever get off the ground today.

Hi Landrew,

The fact of the dinosaur bones might be oxygen related, check out this book from http://www.nick-lane.net/" it talks about how different compositions of the air through the ages gave the possibility for very large insects insects to fly.

[PLAIN]http://www.nick-lane.net/images/Oxygen%20cover.jpg

I like your idea that gravity of our solar system has changed over time, I think there might be one on a more global scale, an expanding Gravity field that might explain "Redshift".

http://en.wikipedia.org/wiki/Redshift" .).

Would that be possible?

Here is a rough sketch to illustrate the idea:

[URL]http://1.bp.blogspot.com/_I6sqljFZpGw/TP9yDXcbwpI/AAAAAAAAAYs/ibHv7h1Ymx8/s1600/Redshift_red.jpg[/URL]

 

[Kracatoan]

Unfortunately, redshift is independant of nearby mass, i.e it is the velocity of the star which emits it, not its mass which determines the degree that the light is redshifted.

Oh and Earth isn't in the Goldilocks zone any more, if we didn't have our atmosphere the planet would be too hot to sustain life.

 

[Michel_vdg]

Unfortunately, redshift is independant of nearby mass, i.e it is the velocity of the star which emits it, not its mass which determines the degree that the light is redshifted.

I don't think you understand very well what 'redshift' is, let me quote wikipedia here:

In physics (especially astrophysics), redshift happens when light seen coming from an object is proportionally shifted to appear more red. Here, the term "redder" refers to what happens when visible light is shifted toward the red end of the visible spectrum. More generally, where an observer detects electromagnetic radiation outside the visible spectrum, "redder" amounts to a technical shorthand for "increase in electromagnetic wavelength" — which also implies lower frequency and photon energy in accord with, respectively, the wave and quantum theories of light.
Redshifts are attributable to the Doppler effect, familiar in the changes in the apparent pitches of sirens and frequency of the sound waves emitted by speeding vehicles; an observed redshift due to the Doppler effect occurs whenever a light source moves away from an observer.(http://en.wikipedia.org/wiki/Redshift" )

I have highlighted the part of the Doppler effect, because a similar 'shift' would happen if you make a sound in the direction of a fan, the harder the fan blows towards the origin of the sound, the further away the speaker appears to be. In a similar way; if the gravity field of our solar system expands over time, than the further away other galaxies seem to be.

 

[Kracatoan]

an observed redshift due to the Doppler effect occurs whenever a light source moves away from an observer.

Which is why I said that the degree of redshift is determined by the velocity of the star which emits it. A misunderstanding? I think not.

 

[Michel_vdg]

Which is why I said that the degree of redshift is determined by the velocity of the star which emits it. A misunderstanding? I think not.

If I may quote your previous post:

redshift ... is the velocity of the star which emits it ...

There is a difference between what is, and what is determined by, as you say in your last post.

When you say is determined by, it could be that the galaxies are moving away, but it could very well, and even more likely be, that it is caused because of the increasing gravity field of our solar system, as I explained in my previous posts. And 'more likely' because all the the galaxies that surround us are moving away, and that would probably mean that we are the center of the universe, isn't that a little bit odd when you look into the skies?

 

[Kracatoan]

it is the velocity of the star which emits it, not its mass which determines the degree that the light is redshifted.

This is just saying that the velocity, not the mass of a star determines the redshift. Nothing wrong with that. I think he confused the first "it" as referring to the relationship between velocity and redshift, when clearly it is the word determines which is that.

Also, the gravity theory makes no sense, on your diagram you have written "Resistance slows down light", but that doesn't happen because we know from experiment that gravity doesn't slow down or speed up light.

Also, galaxies moving away from us makes perfect sense because we can determine distances of galaxies using techniques other than redshift (supernovas, cephied variables) and it is a proven fact that the Universe is expanding. This expansion exactly explains the cosmological redshift we observe, there is no need or room for a theory involving gravity causing redshift.

Also, if the Sun's gravity was causing redshift, we would see the redshift of galaxies change, depending on the relative positions of the galaxy, Earth and sun (due to the light passing different distances from the sun), and this does not happen.

 

[Michel_vdg]

This is just saying that the velocity, not the mass of a star determines the redshift. Nothing wrong with that. I think he confused the first "it" as referring to the relationship between velocity and redshift, when clearly it is the word determines which is that.

granted.

Also, the gravity theory makes no sense, on your diagram you have written "Resistance slows down light", but that doesn't happen because we know from experiment that gravity doesn't slow down or speed up light.

also granted, light moves at a constant speed, what I mean is the frequency of the light is slowed down, and that is what is measured as 'redshift'.

Also, galaxies moving away from us makes perfect sense because we can determine distances of galaxies using techniques other than redshift (supernovas, cephied variables)

Sure it makes sense otherwise the calculations wouldn't match, but an expending gravitation field could also be, and probably more likely.

and it is a proven fact that the Universe is expanding. This expansion exactly explains the cosmological redshift we observe, there is no need or room for a theory involving gravity causing redshift.

There is no need, is what you say, a new explanation shouldn't be just be thrown away because the old one works.

Also, if the Sun's gravity was causing redshift, we would see the redshift of galaxies change, depending on the relative positions of the galaxy, Earth and sun (due to the light passing different distances from the sun), and this does not happen.

This argument is not valid, if redshift would happen because of the suns gravitation field, or because galaxies would be moving further away, then the measurements are in both cases the same, relevant to the positions of the Earth and the sun.

If gravity can bend light, why wouldn't it have an effect on it's frequency, if you bend something you change it's path and change it's properties, there is no other way.

 

[Kracatoan]

The point is, we know for sure galaxies are moving away.

We know for sure that things moving away whilst emitting light increase the light's wavelength, and this can be calculated.

We can find out how fast distant galaxies are moving away from us by tried and tested methods and we can use this speed to find out how much the light MUST have been redshifted.

When the light reaches earth, it has been redshifted by the amount which our calculations predict. Therefore, there is nothing else acting on them.

All the calculations above are not theoretical and are based on equations which are proven to be true.

 

[Michel_vdg]

The point is, we know for sure galaxies are moving away.

We know for sure that things moving away whilst emitting light increase the light's wavelength, and this can be calculated.

We can find out how fast distant galaxies are moving away from us by tried and tested methods and we can use this speed to find out how much the light MUST have been redshifted.

When the light reaches earth, it has been redshifted by the amount which our calculations predict. Therefore, there is nothing else acting on them.

All the calculations above are not theoretical and are based on equations which are proven to be true.

The only thing we know for sure is that there is redshift, and that we can calculate it over time. There can only be 2 possible reasons; one is that things are moving further away from us, the second one is that the light, coming from other stars, is slowed down in frequency due to a factor that is spherical and of which we are the center, and of which I could also say: we can use a gravitational field exponential, instead of speed, to find out how much the light MUST have been redshifted. Now for the first option we should be the center of the universe, for the latter an increasing Solar Gravitation Field is the source, what is the most logic one, and doesn't or sun shine light further and further into space over time?

I know it seems to be foolish, to go against the grain of all the theories of an expending universe, and perhaps I'm really overlooking something. But I would like to repeat the last paragraph of my previous post: If gravity can bend light, why wouldn't it have an effect on it's frequency, if you bend something you change it's path and change it's properties, there is no other way.

 

[thedeester1]

For me all the shifts are irrelivant...The expansion theory was formed over 100 years ago before anyone realized Galactic or Universal Chemistry. Everything we measure is governed by the speed of light...Its a mistake to make that a constant...It works in envoronment..but the speed of light is constant in a vaccuum...As it passes through any mass it will slow. If it is very far away then it will pass through a lot of mass. hence the time it takes to reach us...This I think but cannot prove "yet" will effect the Dopler effect...I can prove however that the further any spectrum of light has to travel then the more it will be slowed by mass.

 

[Ich]

Hi Kracatoan,

the only way to measure cosmological radial velocities is indeed redshift. There are no other tried and tested mehods.

Hi Michel_vdg,

the sun's gravitational potential is much too weak to account for measurable cosmological redshift. Further, there's no such thing as "expanding gravitational fields" causing redshift. Then, the expanding universe idea does not demand that we are at the center of the universe.

Michel_vdg & thedeester1, please make sure you've read the https://www.physicsforums.com/showthread.php?t=17355". Promotion of personal theories is not allowed here.
Try to use PF as a means to learn real science instead, that's what it's for.

 

[thedeester1]

so the speed of light been equal unless it passes through mass or gravity you can time its speed to predict expansion!

 

[Michel_vdg]

the sun's gravitational potential is much too weak to account for measurable cosmological redshift.

If our Sun has the potential to bend starlight in a perpendicular manner, then why shouldn't it have the potential to do so in a direct linear way, do you have a reference for this assumption?

Further, there's no such thing as "expanding gravitational fields" causing redshift.

I find this type of response quite ignorant, it takes us back to a time before Copernicus.

Then, the expanding universe idea does not demand that we are at the center of the universe.

From wikipedia: Hubble's law has two possible explanations. Either we are at the center of an explosion of galaxies—which is untenable given the Copernican Principle—or the Universe is uniformly expanding everywhere. http://en.wikipedia.org/wiki/Big_Bang#Hubble.27s_law_and_the_expansion_of_space"

Michel_vdg & thedeester1, please make sure you've read the https://www.physicsforums.com/showthread.php?t=17355". Promotion of personal theories is not allowed here.

There is a place to do so over here, it is called: https://www.physicsforums.com/forumdisplay.php?f=146" I will gather up my ideas and post them over there if you don't like to have a debate over here.

Try to use PF as a means to learn real science instead, that's what it's for.

There is no need to be so negative. I only wanted to hear/learn what other people think of an "expanding gravitational field" and what the arguments pro or con such an idea are.

 

[Ich]

If our Sun has the potential to bend starlight in a perpendicular manner, then why shouldn't it have the potential to do so in a direct linear way, do you have a reference for this assumption?

I never said there was no influence. It's about 0.000002 %.

There is a place to do so over here, it is called: Independent Research I will gather up my ideas and post them over there if you don't like to have a debate over here.

That's a good idea. Be aware, they have rules there, too. You'll have to do some homework before submitting your work.

 

[Michel_vdg]

I never said there was no influence. It's about 0.000002 %.

Do you really think that it is "much too weak to account for measurable cosmological redshift", if you count that the sun is daily sending out gravity particles and this already for a period of more than 4.000.000.000 years?

Can you imagine gazillions of tiny particle projected from the Sun into space for such a long time, without any significant effects on in coming light from galaxies that are millions of light years away, except for the 0.000002 % of curvature when it shoot just by the sun for half a second?

That's a good idea. Be aware, they have rules there, too. You'll have to do some homework before submitting your work.

Thanks for the tip.

 

[Darpan Dahiya]

I don't agree atleast on the flying dinosaur theory.

 

[Michel_vdg]

I don't agree atleast on the flying dinosaur theory.

The idea of the dinosaurs isn't that crazy if you see how astronauts fly on the moon where it is a combination of gravity and super low atmospheric pressure/density that makes them light on their feet.

In the same way an expanding gravity field creates a more dense heliosphere, and like "thedeester1" already posted:

Everything we measure is governed by the speed of light...Its a mistake to make that a constant...It works in envoronment..but the speed of light is constant in a vaccuum...As it passes through any mass it will slow. If it is very far away then it will pass through a lot of mass. hence the time it takes to reach us...This I think but cannot prove "yet" will effect the Dopler effect...I can prove however that the further any spectrum of light has to travel then the more it will be slowed by mass.

Also have a look at, http://en.wikipedia.org/wiki/Pioneer_anomaly" :

The Pioneer anomaly or Pioneer effect is the observed deviation from predicted trajectories and velocities of various unmanned spacecraft visiting the outer solar system, most notably Pioneer 10 and Pioneer 11.
Both Pioneer spacecraft are escaping from the solar system, and are slowing down under the influence of the Sun's gravity. Upon very close examination, however, they are slowing down slightly more than expected. The effect can be modeled as a slight additional acceleration towards the Sun.
The anomaly has no universally accepted explanation. The explanation may be mundane, such as measurement error, thrust from gas leakage or uneven radiation of heat. However, it is also possible that current physical theory does not correctly explain the behaviour of the craft relative to the sun. (http://en.wikipedia.org/wiki/Pioneer_anomaly" )

As mentioned in the article, there are multiple possible explanations, also some in correlation with gravity, and they could also be applicable to cause Redshift, if you take in account that the structure of our solar system is expanding.

A thought experiment: Imagine yourself having a pair of glasses that are constantly collecting dust, and every morning when you put on your glasses, you say: "Hey, the world is getting darker!". Well it might be the same for those who like to think that the stars are moving away from us.

 

[Chronos]

I'm not assuming or asserting anything. I'm just asking questions. If you don't have the answers, insulting won't make you smarter.

No insult intended. You are assuming universal expansion is - universal. It is not. It only applies when other forces [e.g., gravity] are too weak to resist.