Possible matter being Created/Destroyed?

[Ich]

I don't understand how this is a philosophical point. Either the expansion of the universe DOES have an effect on local scales or it DOES NOT have an effect. I see absolutely NOTHING about that that is philosophical.

Right. But if it does not have an effect, the question whether space is expanding there or not is philosophical. And that's what I'm claiming. Have a look at Naty1's thread here.

 

[Chronos]

Conventional thinking is it has no effect. But, theoretically, it could have increased the size of the solar system by about 40 meters over the last 4.5 billion years - a bit less than expected merely due to radiative loss of solar mass over that same time frame.

 

[Drakkith]

Conventional thinking is it has no effect. But, theoretically, it could have increased the size of the solar system by about 40 meters over the last 4.5 billion years - a bit less than expected merely due to radiative loss of solar mass over that same time frame.

How would it cause the solar system to expand if gravity holds us to the Sun? I can understand how galaxies get carried away from each other, but they are not bound.

 

[Ich]

Conventional thinking is it has no effect. But, theoretically, it could have increased the size of the solar system by about 40 meters over the last 4.5 billion years [...]

What are you referring to?

 

[Naty1]

ICH: post #41

Originally Posted by Naty1

The fact that gravitationally bound local systems may not move is not the measure of expanding space. Another way to think of it is that over billions of years, if nothing else changed, space would continue to expand but gravitationally bound local systems would not.

(correct, but then: nothing is a measure of expanding space, except the things that are moving away from each other. If they aren't, well, what's the point of talking about expanding space?)

Not quite, if I understand your statement: sure, only intergalatic distances have measureable expansion of space. My perspective has so far been, and I may be way off base here, that a locally bound gravitational solar system does not inhibit space itself from expanding. [Unlike, for example, the balloon analogy where ALL space expansion moves massive objects.] In other words, we all agree, I think, that if our solar system were NOT present, it's empty space would expand infinitesimally in that volume; Maybe not by a measureable amount of course. Now we plop in a sun, some planets and moons there...will that stop space from expanding?? Is the presence of mass a glue that ties space together?? I have not so far thought so. [Does more curved space expand 'less' than more flat space??

 

[Ich]

Let me quote the FAQ right before the one you quoted:

Are galaxies really moving away from us or is space just expanding?

This depends on how you measure things, or your choice of coordinates. [...]

See what I mean? Expanding space and moving things are (at least locally) different descriptions of the same phenomenon. Just different coordinates. You can't decide which coordinate system is the correct one, as both are valid.

I think, that if our solar system were NOT present, it's empty space would expand infinitesimally in that volume

In a patch of empty space, you can easily use coordinates with H=70 km/s/km. Or you can use static coordinates. Both are valid descriptions of - nothing. It makes no difference observationally, so the question is a philosophical one.

 

[Drakkith]

In a patch of empty space, you can easily use coordinates with H=70 km/s/km. Or you can use static coordinates. Both are valid descriptions of - nothing. It makes no difference observationally, so the question is a philosophical one.

Would light passing through an area of space with or without something such as our solar system have it's wavelength stretched a tiny amount? Or how about while moving past or through a large galaxy?

 

[Eimacman]

Greetings George Jones:

That is the answer that I needed, I must study this further for my math is not as good as I would like.

Thank you.

Eimacman.

 

[Ich]

Would light passing through an area of space with or without something such as our solar system have it's wavelength stretched a tiny amount?

Depends on the observers you choose. If emitter and receiver are at rest wrt each other, there's no shift. If both are "comoving", i.e. moving away from each other according to the Hubble law, there is redshift, obviously.

In a "static space" description, the first observers don't move, and the second observers move away from each other.
In an "expanding space" description, the second observers don't move, and the first observers have a peculiar velocity that exactly cancels the cosmological redshift.

The results are the same in both descriptions.

 

[Chronos]

A photon approaching a gravitational field is blue shifted, as it exits that same gravitational field it is redshifted by exactly the same amount.

 

[Drakkith]

Depends on the observers you choose. If emitter and receiver are at rest wrt each other, there's no shift. If both are "comoving", i.e. moving away from each other according to the Hubble law, there is redshift, obviously.

In a "static space" description, the first observers don't move, and the second observers move away from each other.
In an "expanding space" description, the second observers don't move, and the first observers have a peculiar velocity that exactly cancels the cosmological redshift.

The results are the same in both descriptions.

Lets say I observe light from a galaxy moving away at exactly redshift z=0.1, and that light happens to go through a galaxy on the way to me. Is the galaxy I am observing the same distance as another galaxy who's redshift is also exactly z=0.1 who's light is not going through another galaxy before reaching me?

 

[Ich]

Lets say I observe light from a galaxy moving away at exactly redshift z=0.1, and that light happens to go through a galaxy on the way to me. Is the galaxy I am observing the same distance as another galaxy who's redshift is also exactly z=0.1 who's light is not going through another galaxy before reaching me?

The galaxy introduces some positive curvature, so I'd say that the distance in this direction is a little bit larger. See Shapiro delay.
But I don't see how this pertains to the discussion.

 

[Naty1]

ICH

Originally Posted by Ned Wright

Are galaxies really moving away from us or is space just expanding?

This depends on how you measure things, or your choice of coordinates. [...]

See what I mean? Expanding space and moving things are (at least locally) different descriptions of the same phenomenon. Just different coordinates. You can't decide which coordinate system is the correct one, as both are valid.

I do see what you mean...now...I think that's the best perspective...Thanks!

 

[Naty1]

Found it! the 'classic discussion from 2007:

Does Space Expand...[Wallace IS a cosmologist]

https://www.physicsforums.com/showthread.php?t=162727&highlight=current+flow&page=2

 

[Chronos]

The effect of cosmological expansion on the solar system is negligible. For discussion see http://arxiv.org/pdf/astro-ph/9803097v1.pdf

 

[jimpy]

hi Samuel99
it takes a lot of courage for you to post like this.I'm no expert by any means but there are a few issues worth you following up on here.
Firstly,in the case of the expanding accelerating universe then the observations that are made are all historic.
The most recent have just happened here.The rest are history.
So now I'll stick my neck out and we'll see what happens.
I think that the only location that the accelerating expansion of the universe is identifiable(is being the operative word)is here and now.
When we peer into the night sky we have a log of what happened in our yesterdays,right upto the beginning if we accept the idea that "The Big Bang"was an event that actually happened in our yesterdays.
Secondly I don't necessarily understand why 40 metres in 4000 light years is irrelevant.
I haven't been taught that rule.

It all depends on the significance of the variation.
Currently we are discussing here speculative possibilities which have widespread approval in the world of scientists.
The theories involved in your post are amongst the most complex ever advanced by mankind.
One of the first books in English relating to this area is "The Mathematical Theory of Relativity" by an Englishmen called Arthur Eddington" which was published in 1926 and is a second book of his about the theories of Albert Einstein.
It is called "The Mathematical Theory of Relativity"
A very important remark in the introduction to this work is as follows:
(he is discussing determining what length means when we exchange ideas)
"But to catalogue all the precautions and provisos in the operation of determining even so simple a thing as length is a task which we shirk.We might take refuge in the statement that the task though laborious is straightforward,and that the practical physicist knows the whole task without us writing it down for him."
It goes on from here,if you can get the book from your school library you can read the whole thing.It is on page 6 of the introduction.
I am impressed by your spirit,
Jimpy

 

[Ich]

The effect of cosmological expansion on the solar system is negligible. For discussion see http://arxiv.org/pdf/astro-ph/9803097v1.pdf

There's a discussion of this discussion here.

 

[Chronos]

Yes, my apologies, I noticed that after posting the link.

 

[Eimacman]

Universal expansion does have an effect. However, how that effect is felt depends on the binding energy/force and the kind of binding energy/force. Take an atom for example. It will not distort or deform at all because of universal expansion until the force of such expansion reaches parity with all the forces holding an atom together, Electromagnetic, Strong and Weak Nuclear, Electroweak etc. At that point the atom will suddenly come apart. Other binding energies/forces such as molecular bond strength, Vander Waals attraction, Gravitation, and so on will react according to their various properties. Any change caused by such expansion is significant if a sufficient amount of time passes, 10^{1000000} years for example.

Even then, any matter thus effected will only be changed into energy, and with entropy →∞ such energy will not most likely be useful.

 

[phinds]

Universal expansion does have an effect. However, how that effect is felt depends on the binding energy/force and the kind of binding energy/force. Take an atom for example. It will not distort or deform at all because of universal expansion until the force of such expansion reaches parity with all the forces holding an atom together, Electromagnetic, Strong and Weak Nuclear, Electroweak etc. At that point the atom will suddenly come apart. Other binding energies/forces such as molecular bond strength, Vander Waals attraction, Gravitation, and so on will react according to their various properties. Any change caused by such expansion is significant if a sufficient amount of time passes, 10^{1000000} years for example.

Even then, any matter thus effected will only be changed into energy, and with entropy →∞ such energy will not most likely be useful.

Can you provide any citation to a paper that shows that there is ANY expectation that "dark energy" will ever become strong enough to overcome those forces? I have never heard that before.

 

[Eimacman]

Greetings, phinds:

I believe that this article may be enlightening on the subject: http://arxiv.org/pdf/1202.4060v2.pdf


Eimacman.

 

[phinds]

Greetings, phinds:

I believe that this article may be enlightening on the subject: http://arxiv.org/pdf/1202.4060v2.pdf


Eimacman.

Thanks for that. I'm not able to judge the merit of their argument, but it's certainly interesting.

 

[phinds]

My understanding was that distances between objects in gravitationally-bound systems such as galaxies and solar systems are not increasing.

This seems to be a contentious issue, but I agree w/ your point of view (not that the universe cares whether we think that way or not)

 

[Ich]

Note that the Big Rip scenario violates certain basic assumptions in physics, so that it is rejected as a serious possibility by mainstream cosmologists. Still, it's interesting and pretty cool, as you can use words like "phantom energy" in that context.

 

[twofish-quant]

This seems to be a contentious issue, but I agree w/ your point of view (not that the universe cares whether we think that way or not)

The issue is that we don't know what dark energy consists of. So in order to describe it, we talk about "w". w = pressure / density.

What the paper talks about is what happens in the universe for given values of "w". The observed value of w seems to be -1. If w==-1, then gravitationally bound objects are stable. If w is less than -1, then you get a runaway effect called the "big rip". The universe expands, this releases energy, which causes the universe to expand more, which releases more energy... Eventually the entire universe expands so quickly that subatomic particles are destroyed... The reason that everything gets destroyed if w<-1, is that the speed of expansion of the universe goes to infinity, which destroys everything.

 

[Farahday]

The Big Bang theory most emphatically does NOT say that it started at a point, in fact, it says quite the opposite ... it started EVERYWHERE. There is no center, there is no edge. There was never a "point of origin".

You need to read up on cosmology, as I have already suggested.

It started? Really?

Before something can change, before it can act or be acted upon, it must exist.

This is a rather simple axiom, intrinsically self-evident since any who might dissent must believe in things that don't exist. Existence in the absence of change is possible, change in the absence of existence is not. The fact that existence is required in order for change to occur explicitly means cause and effect is a function of (derived from) the phenomenon of existence. The Universe didn't suddenly transform from a condition of non-existence into a state of physical being because existence isn't a condition or a state of being, it is the phenomenon of being, itself. No phenomenon can be the product of its own subordinate derivative and the incongruities that result from any conceivable premise of creation are obvious.

Logically, existence is NOT the result of cause and effect (creation/beginning)

 

[phinds]

It started? Really?

Before something can change, before it can act or be acted upon, it must exist.

This is a rather simple axiom, intrinsically self-evident since any who might dissent must believe in things that don't exist. Existence in the absence of change is possible, change in the absence of existence is not. The fact that existence is required in order for change to occur explicitly means cause and effect is a function of (derived from) the phenomenon of existence. The Universe didn't suddenly transform from a condition of non-existence into a state of physical being because existence isn't a condition or a state of being, it is the phenomenon of being, itself. No phenomenon can be the product of its own subordinate derivative and the incongruities that result from any conceivable premise of creation are obvious.

Logically, existence is NOT the result of cause and effect (creation/beginning)

I should have said it EXPANDED from everywhere. Modern cosmology does not make any statement about what the singularity was, so you MAY be right. Quantum mechanics is weird enough that you may also be wrong.

 

[Whovian]

Okay. As you appear to be attacking ever minor wording issue of Phinds's, I'll try to counter that argument.

I believe Phinds was saying that it occurred everywhere, not that it started everywhere.

Before something can change, before it can act or be acted upon, it must exist

Perhaps you mean as it can change, as it can act or be acted upon?

EDIT: Looks like Phinds beat me to it!

 

[twofish-quant]

Before something can change, before it can act or be acted upon, it must exist.

I don't think that "cosmology by word game" is a valid approach. One problem is that "ordinary language" is far, far too imprecise a tool to make a scientific argument. The reason physicists use a lot of math is that you can define things to extreme precision. When a mathematician uses the term "exist" they write down a precise and unambigious definition of what they mean by "exist"

This is a rather simple axiom, intrinsically self-evident since any who might dissent must believe in things that don't exist.

Sorry, I don't accept these sorts of axiom. The reason that I don't is that I've seen very weird things in physics, and a lot of those things are hard, perhaps impossible to describe with ordinary language which is designed to describe the things that we are used to in our daily life.

For example, if you deal with electrons you quickly find that they don't follow "ordinary rules of logic." They do follow rules, and these rules can be defined mathematically, but they are just not the ordinary rules of logic. So when you describe the behavior of electrons, you have to use special terms, and learn a whole new set of logic.

http://en.wikipedia.org/wiki/Quantum_logic

And there is an entire branch of mathematics devoted to non-classical logic

http://en.wikipedia.org/wiki/Non-classical_logic

If you try to reason about electrons with ordinary logic and ordinary language, you end up with a mess. So when people start using ordinary logic and ordinary language to reason about the big bang, it's hard for me to accept those arguments.

Logically, existence is NOT the result of cause and effect (creation/beginning)

Which logic?

 

[Farahday]

I don't think that "cosmology by word game" is a valid approach. One problem is that "ordinary language" is far, far too imprecise a tool to make a scientific argument. The reason physicists use a lot of math is that you can define things to extreme precision. When a mathematician uses the term "exist" they write down a precise and unambigious definition of what they mean by "exist"

Have a physical (not necessarily material) presence in the cosmos. Must have quality (even inertness is a quality), quantity (no matter how infinitesimal or large) and relative location (you can point to it).

Sorry, I don't accept these sorts of axiom. The reason that I don't is that I've seen very weird things in physics, and a lot of those things are hard, perhaps impossible to describe with ordinary language which is designed to describe the things that we are used to in our daily life.

Yes, like bosons that can occupy the same physical location simultaneously. Conditions can exist simultaneously at multiple locations, but existences cannot. I view bosons as a phenomenon - a condition propagated among and between fields - in fact the phenomenon of mass, itself, is just a condition...just ask Uncle Al Einbeermug...that can appear here and reappear there without traversing the distance between or even be partly here and partly there, creating vast uncertainty as to where it might actually be. Existences can't do that, only conditions have that capability.

For example, if you deal with electrons you quickly find that they don't follow "ordinary rules of logic." They do follow rules, and these rules can be defined mathematically, but they are just not the ordinary rules of logic. So when you describe the behavior of electrons, you have to use special terms, and learn a whole new set of logic.

http://en.wikipedia.org/wiki/Quantum_logic

Haldane tells us that the world is not only stranger than we imagine, it is stranger than we can imagine. But Occam readily assures us that if theories sound far-fetched, it's probably because they are.

 

[phinds]

Haldane tells us that the world is not only stranger than we imagine, it is stranger than we can imagine. But Occam readily assures us that if theories sound far-fetched, it's probably because they are.

No, not in quantum mechanics.

 

[Farahday]

No, not in quantum mechanics.

Nor in the land of Oz.

 

[Drakkith]

But Occam readily assures us that if theories sound far-fetched, it's probably because they are.

This is incorrect.

Occam's razor (also written as Ockham's razor, Latin lex parsimoniae) is the law of parsimony, economy or succinctness. It is a principle urging one to select among competing hypotheses that which makes the fewest assumptions and thereby offers the simplest explanation of the effect.

As you can see, this has nothing to do with sounding far fetched. A great many things can sound far fetched but are fundamental principles and theories in science.

 

[Farahday]

This is incorrect.
As you can see, this has nothing to do with sounding far fetched. A great many things can sound far fetched but are fundamental principles and theories in science.

Yes, they are on the Razor's edge.
If you quote a few, I'd be happy to cuss and discuss their validity. Theories and principles are very different. I know of few fundamental principles that aren't the personification of simplicity.

 

[Drakkith]

Yes, they are on the Razor's edge.

What does that even mean?

 

[thunderhadron]

Hi friends in some of the theories it is said that the universe is expanding like a wet bread. Like when a nan maker makes a nan and throws it in the vertically upward the nan starts rotating and starts expanding in the outward direction from everywhere. Same as the case with universe also, if the nan has two much holes associated with it. Universe as the white wet bread rotating very very very slowly and hole as the galaxies in it.

 

[Drakkith]

Hi friends in some of the theories it is said that the universe is expanding like a wet bread. Like when a nan maker makes a nan and throws it in the vertically upward the nan starts rotating and starts expanding in the outward direction from everywhere. Same as the case with universe also, if the nan has two much holes associated with it. Universe as the white wet bread rotating very very very slowly and hole as the galaxies in it.

Yes, this is similar to the raisins in rising bread analogy. But remember that it is just an analogy. The full description is deals heavily with advanced mathematics and is very difficult to accurately describe with just layman words.

 

[Farahday]

If the cosmos were finite there would be a finite number of existences, elements with defined parameters like volume and location (screw the cat). It would be easy to summarize them and produce a map of the cosmos at any point in time. This would show where the universal wall was located relative to each point within.

We may, in fact, have just run into it.

 

[phinds]

if the cosmos were finite there would be a finite number of existences, elements with defined parameters like volume and location (screw the cat). It would be easy to summarize them and produce a map of the cosmos at any point in time. This would show where the universal wall was located relative to each point within.

We may, in fact, have just run into it.

huh ?

 

[Drakkith]

If the cosmos were finite there would be a finite number of existences, elements with defined parameters like volume and location (screw the cat). It would be easy to summarize them and produce a map of the cosmos at any point in time. This would show where the universal wall was located relative to each point within.

We may, in fact, have just run into it.

None of this makes any sense in regards to actual science. Please, stop speculating and make some sense or I will report you for trolling.