If there is no end to the space

[owl]

Two questions posted above today. Anyone? (post #223)

Edited March 14, 2011 by owl

[Iggy]

Answered in post #218.

[HamsterPower]

wow this thread has become huge....

I was only curious...so let me get it straight

answer to my question, nobody really knows

but it is assumed that the space is infinite but stars are finite?

 

hmhmhmhm i hope i got this right

 

[Spyman]

It is assumed that all of space is homogeneously filled with stars.

 

The observable matter in all directions around us, is from our viewpoint in the Universe spread uniformly throughout the universe. In accordance with the cosmological principle modern cosmology assumes that our location in the Universe is normal and don't differentiate from remaining regions. Thus all unseen parts of the entire Universe are thought to be filled with equal quantities of stars in roughly the same configurations as we can see from Earth.

 

A finite space have finite stars and likewise if space is infinite then it's likely stars are infinite also.

[HamsterPower]

 

 

The observable matter in all directions around us, is from our viewpoint in the Universe spread uniformly throughout the universe. In accordance with the cosmological principle modern cosmology assumes that our location in the Universe is normal and don't differentiate from remaining regions. Thus all unseen parts of the entire Universe are thought to be filled with equal quantities of stars in roughly the same configurations as we can see from Earth.

 

 

 

I don't get this part, can you use easier words?

[imatfaal]

The cosmological principle states that we see the same (on large scales) whichever direction we look AND that we would see the same if we were looking from somewhere else in the universe.

 

The large scale bit can sometimes confuse - as an idea try looking at google satellite maps of London - very high magnification you can see the people and it is clearly not all the same (homogeneous), but if you zoom out it's just a grey blob. When you look at large scales and average out the universe is very boring and uniform - and with this we can make predictions.

[Djordje]

so is space really expanding or are the things in it moving away from each other in an already infinite space?

 

IMHO, if space is expanding, it has to have bounds.

[Airbrush]

I don't get this part, can you use easier words?

 

Galaxies, and clusters of galaxies, and the Cosmic Microwave Background Radiation, are all very uniformly distributed throughout visible space. There are great voids and filamentary structures but these all appear to be very uniformly distributed in every direction.

[HamsterPower]

so if they are uniformly distributed, why don't we see a bright night sky?

aren't they going to be shining from every direction because of infinite numbers of stars?

 

I feel like i am the only one who doesn't get this

[Airbrush]

so if they are uniformly distributed, why don't we see a bright night sky?

aren't they going to be shining from every direction because of infinite numbers of stars?

 

I feel like i am the only one who doesn't get this

 

We don't see a bright night sky because most stars, and all galaxies, are so far away that they are invisible to the naked eye. Even with the most powerful telescopes we don't see a bright sky, because beyond a great enough distance, it is so far back in time that there were no galaxies and no stars yet formed.

Edited March 16, 2011 by Airbrush

[HamsterPower]

We don't see a bright night sky because most stars, and all galaxies, are so far away that they are invisible to the naked eye. Even with the most powerful telescopes we don't see a bright sky, because beyond a great enough distance, it is so far back in time that there were no galaxies and no stars yet formed.

 

AH i see,,,

now you guys could have told me this without having to write 12 pages of argument

 

*chuckles*

[owl]

I was looking for a straight answer about the distance between sun and earth in the real world compared to what a near-light-speed-traveler would see approaching and whizzing by our system. There is a consensus among astronomers about that distance from earth's frame of reference. So I was wondering how relativity theorists justify the claim that the distance really does vary just because it would be "seen" to vary by the above high speed travelers.

Also that, according to Lorentz transformation, the sun actually shrinks and changes temperature "as seen from" the above near-light-speed extremes.

You can not say that what the rocket jockey sees at near light speed makes the earth move closer to the sun. that is just nonsense! Likewise that the Amazing Lorentz transforms the actual size and temperature of the sun. Total nonsense!

Finally, if a guy goes left 540 million miles and a laser goes right 670 million miles, both in the same hour, the guy is just wrong if he thinks that, since his travel and the light's travel total 1210 miles, that light traveled 1210 miles an hour. That figure is the total sum of distances traveled by him (to the left) and by light (to the right.)

I can not be more clear. If that is confused, then I am confused.

Edited March 17, 2011 by owl

[lemur]

IMHO, if space is expanding, it has to have bounds.

How can something that is expanding faster than light (or anything else that can traverse it) have "bounds," unless by "bounds" you mean places you can't get to? I can see how you could conceptualize an unreachably receding horizon as a type of boundary, but since you never actually reach it, it's really just more of a concept than a physical boundary, isn't it? I mean, it's not a THING.

Edited March 17, 2011 by lemur

[owl]

First, apologies to HampserPower for my part in hijacking this thread... It seemed to be lying dormant....

Of course there is no end to space! I jumped in here with a logical argument to that effect. What boundary? What beyond the imagined boundary? Nonsense. .. "and beyond that?...

 

But I want to address the following:

 

View Postdragonstar57, on 15 January 2011 - 10:31 AM, said:

so is space really expanding or are the things in it moving away from each other in an already infinite space?

 

IMHO, if space is expanding, it has to have bounds."

...............

 

(sorry, don't have the hang of quote boxes/tools)

 

No one is asking "What is space?"... assuming (with Einstein, et. al) that "it" is some kind of medium (not just 'empty' space) that expands and is bent/curved and all. How does infinite emptiness expand?

 

It is not presently codified by the most popular cosmologists, but I think that "the things in it (space... are) moving away from each other in an already infinite space?"

 

To the last comment above: If space is emptiness, it is no-thing, not even an "it' to expand. And, as above you can not imagine an end to empty space. It must, by reason of 'no possible end' be infinite!

 

What expands, as I envision it and

contrary to popular 'wisdom' is the whole 'shebang' from the Bang... all matter/energy/plasma and the forces they generate... all expanding as the cosmic fireworks explosion... but within a 'shell' of thickness beyond which we can not see. (It's all isotropic and homogeneous as far as we can see from here... within the thickness of the 'rubber membrane of the expanding balloon.')

 

...For what it's worth. Cosmology is the turf of visionaries. No proofs available for what is beyond our "cosmic event horizon"... as far as we can see. But some things are obvious... to me... meaning 'all of the above.'

[uncool]

You are consuming Iggy's countdown.

 

7.

Let's consider an event that happens on Earth (x1 = 0) at time 0 (t1 = 0). Then consider an event that happens on the sun (x2 = 1 AU) 10 minutes later in the Earth's frame of reference (t2 = 10 minutes). Then the spacetime interval will be:

 

(c(t2 - t1))^2 - (x2 - x1)^2 = (10 lightminutes)^2 - (1 AU)^2 = 9.97562483 × 10^21 m^2.

 

Now, the claim is that in all frames, the spacetime interval will be the same.

=Uncool-

Edited March 17, 2011 by uncool

[michel123456]

Let's consider an event that happens on Earth (x1 = 0) at time 0 (t1 = 0). Then consider an event that happens on the sun (x2 = 1 AU) 10 minutes later in the Earth's frame of reference (t2 = 10 minutes). Then the spacetime interval will be:

 

(c(t2 - t1))^2 - (x2 - x1)^2 = (10 lightminutes)^2 - (1 AU)^2 = 9.97562483 × 10^21 m^2.

 

Now, the claim is that in all frames, the spacetime interval will be the same.

=Uncool-

 

That is [math]S^2[/math], not [math]S[/math]. IIRC units of spacetime interval are meters, not square meters.

And you came at countdown minus 105.

But I give you one point because you used the correct formula.

Edited March 17, 2011 by michel123456

[Spyman]

The observable matter in all directions around us, is from our viewpoint in the Universe spread uniformly throughout the universe. In accordance with the cosmological principle modern cosmology assumes that our location in the Universe is normal and don't differentiate from remaining regions. Thus all unseen parts of the entire Universe are thought to be filled with equal quantities of stars in roughly the same configurations as we can see from Earth.

I don't get this part, can you use easier words?

Sure, how about like this:

 

Everything we can see all around us is placed in a similar fashion everywhere in the Universe. Modern scientists thinks that the whole Universe is like our view from Earth, nothing special here and nothing special somewhere else. So that would mean that the whole Universe is filled with stars similar to our view.

 

so if they are uniformly distributed, why don't we see a bright night sky?

aren't they going to be shining from every direction because of infinite numbers of stars?

IF and that is only IF the Universe is infinite, which we currently don't have knowledge of, then there would be a infinite numbers of stars shining on Earth from every direction.

 

The reason we don't see a bright night sky are because:

1) it takes long time for light to reach us from very distant stars and the Universe is not yet old enough,

2) space is able to expand faster that light and thereby increase distances faster than light can traverse them.

 

now you guys could have told me this without having to write 12 pages of argument

The twelve pages of argument are regarding the theory of Relativity with Owl and Michel and doesn't seem to have any end.

(We wrongly thought you "got it" already on the first page, sorry for that mistake.)

 

 

----------

 

 

IMHO, if space is expanding, it has to have bounds.

According to scientific consensus space IS expanding and is NOT thought to have bounds.

 

 

----------

 

 

I was looking for a straight answer ... that is just nonsense! ... Total nonsense! ...

I can not be more clear. If that is confused, then I am confused.

Yes Owl, you are confused because you don't understand the basics of Relativity.

 

Can you give us a good reason to continue explaining when you don't want to learn?

 

The answers have been given several times already, no point in repeating them.

 

 

No one is asking "What is space?"... assuming (with Einstein, et. al) that "it" is some kind of medium (not just 'empty' space) that expands and is bent/curved and all. How does infinite emptiness expand?

In modern cosmology there is no infinite emtiness, space is homogeneously filled with matter and energy.

 

It is not presently codified by the most popular cosmologists, but I think that "the things in it (space... are) moving away from each other in an already infinite space?"

In modern cosmology distance is expanding without objects moving and space doesn't have to be infinite.

 

To the last comment above: If space is emptiness, it is no-thing, not even an "it' to expand. And, as above you can not imagine an end to empty space. It must, by reason of 'no possible end' be infinite!

In modern cosmology space is able to warp/bend/curve which means it could be wrapped around itself.

 

What expands, as I envision it and

...

some things are obvious... to me...

Well, that is your personal opinion of the Universe which you are entitled to have, but it is certainly NOT how modern cosmology envisions the Universe or what the Big Bang theory is about.

 

It is obvious that you don't understand the evidence we already observe on the inside of our horizon.

Edited March 17, 2011 by Spyman

[Djordje]

@Spyman

Well, if you put it that way, you'll have to compare two infinite objects - an infinite space at 2.10 PM and another, larger, also infinite space at 2.11 PM. How can you compare two infinite things? Just curious 'cause this subject is rather confusing for me.

[Spyman]

@Spyman

Well, if you put it that way, you'll have to compare two infinite objects - an infinite space at 2.10 PM and another, larger, also infinite space at 2.11 PM. How can you compare two infinite things? Just curious 'cause this subject is rather confusing for me.

We can not compare any borders of a younger and an older infinite Universe, but we can still measure a change of distances inside it.

 

One way to visualise space expansion is to think of one infinite long ruler reaching across the Universe, then despite us not being able to see the ends of this ruler, we would still able from our local point of view, observe how the length marks on this ruler are receding from each other.

 

Another way of viewing the expansion is to imagine that we have a ruler one meter long which we use to measure space inside the infinite Universe with, but between two measurements we and the ruler has decreased in size, effectively making the Universe to be larger in comparison.

 

The expansion of space is not thought of as a Universe growing like an object inside a large surrounding emptiness, in modern cosmology it is the metric scale of length that is changing inside the Universe.

 

 

The '''metric expansion of space''' is the increase of distance between distant objects in the universe with time.

 

It is an intrinsic expansion - that is, it is defined by the relative separation of parts of the universe and not by motion "outward" into preexisting space. In other words, the universe is not expanding "into" anything outside of itself.

 

Metric expansion is a key feature of Big Bang cosmology and is modeled mathematically with the FLRW metric.

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

 

 

General relativity describes spacetime by a metric, which determines the distances that separate nearby points. The points, which can be galaxies, stars, or other objects, themselves are specified using a coordinate chart or "grid" that is laid down over all spacetime. The cosmological principle implies that the metric should be homogeneous and isotropic on large scales, which uniquely singles out the Friedmann-Lemaître-Robertson-Walker metric (FLRW metric). This metric contains a scale factor, which describes how the size of the Universe changes with time. This enables a convenient choice of a coordinate system to be made, called comoving coordinates. In this coordinate system, the grid expands along with the Universe, and objects that are moving only due to the expansion of the Universe remain at fixed points on the grid. While their coordinate distance (comoving distance) remains constant, the physical distance between two such comoving points expands proportionally with the scale factor of the Universe.

 

The Big Bang is not an explosion of matter moving outward to fill an empty universe. Instead, space itself expands with time everywhere and increases the physical distance between two comoving points. Because the FLRW metric assumes a uniform distribution of mass and energy, it applies to our Universe only on large scales - local concentrations of matter such as our galaxy are gravitationally bound and as such do not experience the large-scale expansion of space.

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

Edited March 17, 2011 by Spyman

[Djordje]

We can not compare any borders of a younger and an older infinite Universe, but we can still measure a change of distances inside it.

 

One way to visualise space expansion is to think of one infinite long ruler reaching across the Universe, then despite us not being able to see the ends of this ruler, we would still able from our local point of view, observe how the length marks on this ruler are receding from each other.

 

Another way of viewing the expansion is to imagine that we have a ruler one meter long which we use to measure space inside the infinite Universe with, but between two measurements we and the ruler has decreased in size, effectively making the Universe to be larger in comparison.

 

The expansion of space is not thought of as a Universe growing like an object inside a large surrounding emptiness, in modern cosmology it is the metric scale of length that is changing inside the Universe.

 

 

The '''metric expansion of space''' is the increase of distance between distant objects in the universe with time.

 

It is an intrinsic expansion - that is, it is defined by the relative separation of parts of the universe and not by motion "outward" into preexisting space. In other words, the universe is not expanding "into" anything outside of itself.

 

Metric expansion is a key feature of Big Bang cosmology and is modeled mathematically with the FLRW metric.

http://en.wikipedia....ansion_of_space

 

 

General relativity describes spacetime by a metric, which determines the distances that separate nearby points. The points, which can be galaxies, stars, or other objects, themselves are specified using a coordinate chart or "grid" that is laid down over all spacetime. The cosmological principle implies that the metric should be homogeneous and isotropic on large scales, which uniquely singles out the Friedmann-Lemaître-Robertson-Walker metric (FLRW metric). This metric contains a scale factor, which describes how the size of the Universe changes with time. This enables a convenient choice of a coordinate system to be made, called comoving coordinates. In this coordinate system, the grid expands along with the Universe, and objects that are moving only due to the expansion of the Universe remain at fixed points on the grid. While their coordinate distance (comoving distance) remains constant, the physical distance between two such comoving points expands proportionally with the scale factor of the Universe.

 

The Big Bang is not an explosion of matter moving outward to fill an empty universe. Instead, space itself expands with time everywhere and increases the physical distance between two comoving points. Because the FLRW metric assumes a uniform distribution of mass and energy, it applies to our Universe only on large scales - local concentrations of matter such as our galaxy are gravitationally bound and as such do not experience the large-scale expansion of space.

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

 

Thanks for this ultra informing reply

[Airbrush]

....

Of course there is no end to space! I jumped in here with a logical argument to that effect. What boundary? What beyond the imagined boundary? Nonsense. .. "and beyond that?...

 

...If space is emptiness, it is no-thing, not even an "it' to expand. And, as above you can not imagine an end to empty space. It must, by reason of 'no possible end' be infinite!

 

...but within a 'shell' of thickness beyond which we can not see. (It's all isotropic and homogeneous as far as we can see from here... within the thickness of the 'rubber membrane of the expanding balloon.')

 

...For what it's worth. Cosmology is the turf of visionaries. No proofs available for what is beyond our "cosmic event horizon"... as far as we can see. But some things are obvious... to me... meaning 'all of the above.'

 

Nice thinking. However, there can be a kind of "barrior" or transition to a different kind of space. Our region of the universe seems very uniform, yet beyond our visual horizon space may transition into a strange realm, like a region of antimatter, or something unimagined.

 

Space is not nothing, and not empty. Virtual particles and antiparticles pop out of nothing and go back into nothing. So empty space is full of potentiality. Even a big bang can pop out of emptiness.

 

I like your balloon analogy which I also considered. The universe is an expanding shell like a balloon, but the thickness of the balloon is hundreds of Billions of light years thick. We are in the middle of that expanding away from some great cosmic center where the big bang originated. Folks around here don't like that idea much.

[Spyman]

I like your balloon analogy which I also considered. The universe is an expanding shell like a balloon, but the thickness of the balloon is hundreds of Billions of light years thick. We are in the middle of that expanding away from some great cosmic center where the big bang originated. Folks around here don't like that idea much.

Maybe folks despise it because that model has already been ruled out by observations.

 

Scientific consensus is not a popularity contest which Relativity and Big Bang theory won due to fancy appeal.

 

It is nothing wrong with having faith and belif in a personal opinion but before you turn down and judge accepted scientific models, I think it would be a very good idea to acquire knowledge and understanding about them.

 

 

This is the current evidence and knowledge we have that you refuse to accept:

 

Observational evidence

Theoretical cosmologists developing models of the universe have drawn upon a small number of reasonable assumptions in their work. These workings have led to models in which the metric expansion of space is a likely feature of the universe. Chief among the underlying principles that result in models including metric expansion as a feature are:

• the Cosmological Principle which demands that the universe looks the same way in all directions (isotropic) and has roughly the same smooth mixture of material (homogeneous).
  
• the Copernican Principle which demands that no place in the universe is preferred (that is, the universe has no "starting point").
  

Scientists have tested carefully whether these assumptions are valid and borne out by observation. Observational cosmologists have discovered evidence - very strong in some cases - that supports these assumptions, and as a result, metric expansion of space is considered by cosmologists to be an observed feature on the basis that although we cannot see it directly, scientists have tested the properties of the universe and observation provides compelling confirmation. Sources of this confidence and confirmation include:

• Hubble demonstrated that all galaxies and distant astronomical objects were moving away from us, as predicted by a universal expansion. Using the redshift of their electromagnetic spectra to determine the distance and speed of remote objects in space, he showed that all objects are moving away from us, and that their speed is proportional to their distance, a feature of metric expansion. Further studies have since shown the expansion to be extremely isotropic and homogeneous, that is, it does not seem to have a special point as a "center", but appears universal and independent of any fixed central point.
  
• In studies of large-scale structure of the cosmos taken from redshift surveys a so-called "End of Greatness" was discovered at the largest scales of the universe. Until these scales were surveyed, the universe appeared "lumpy" with clumps of galaxy clusters and superclusters and filaments which were anything but isotropic and homogeneous. This lumpiness disappears into a smooth distribution of galaxies at the largest scales.
  
• The isotropic distribution across the sky of distant gamma-ray bursts and supernovae is another confirmation of the Cosmological Principle.
  
• The Copernican Principle was not truly tested on a cosmological scale until measurements of the effects of the cosmic microwave background radiation on the dynamics of distant astrophysical systems were made. A group of astronomers at the European Southern Observatory noticed, by measuring the temperature of a distant intergalactic cloud in thermal equilibrium with the cosmic microwave background, that the radiation from the Big Bang was demonstrably warmer at earlier times. Uniform cooling of the cosmic microwave background over billions of years is explainable only if the universe is experiencing a metric expansion.
  

Taken together, the only theory which coherently explains these phenomena relies on space expanding through a change in metric.

http://en.wikipedia.org/wiki/Metric_expansion_of_space#Observational_evidence

 

Lets repeat that last part once more so that the information really can sink in:

 

"Taken together, the only theory which coherently explains these phenomena relies on space expanding through a change in metric."

 

It is not only the best theory we have, it is totally without competition, there is currently no other model that can explain our observations.

 

 

Do you like Owl also reject Relativity and have your own personal diverging variant of that theory too?

Edited March 17, 2011 by Spyman

[owl]

Spyman:

"Do you like Owl also reject Relativity and have your own personal diverging variant of that theory too?"

 

I don't "reject Relativity" per se. (Cap for being an absolute?) I have not yet reconciled the well proven constant speed of light with the claim of relativity that, for instance, sun-earth distance actually changes with every possible near-light-speed frame of observational reference... or that, as per Lorentz transformation, the size and temperature of the sun actually changes, as extreme frames of reference claim.

 

It is in fact absurd to believe that cosmic bodies move closer and further from each other just because it looks that way from a near-light-speed frame of reference.

 

PS: Spyman ignored (and the standard model he belabors does not consider) the scale of the above model relative to our very small sphere of visibility deeply embedded in the "rubber" of the expanding balloon membrane. If we can nowhere near see to the inner or outer extreme of the "rubber's thickness," of course what we can see will and does appear isomorphic and homogeneous.

Edited March 17, 2011 by owl

[Airbrush]

Spyman: "It is not only the best theory we have, it is totally without competition, there is currently no other model that can explain our observations.

 

"Do you like Owl also reject Relativity and have your own personal diverging variant of that theory too?"

 

I don't reject relativity of any sort. Thanks for posting the observational evidence above. And yet after reading it I don't see how it rules out what I will call the "Revised Balloon Analogy (RBA)". How does the observational evidence show that our region of space is not comparable to a tiny area inside the giant expanding skin of the balloon, and the skin of the balloon is over 50 Billion light years thick?

Edited March 17, 2011 by Airbrush

[owl]

Spyman:

"The Big Bang is not an explosion of matter moving outward to fill an empty universe. Instead, space itself expands with time everywhere and increases the physical distance between two comoving points."

 

This is repetition of the "litany" of the presently accepted doctrine, stated as a fact.

I doubt if you have ever considered the ontology of what "space" IS, that "it" expands and all as per the accepted doctrine.I doubt if you have ever thought twice about the possibility that space is simply empty volume, without "end." What IS "it" that expands? This is an ontological question, so it may be over your head as a hard core empirical, well conditioned to accepted doctrine, "scientist."

I doubt that you will even consider the extremely vast scale of the "balloon" model I have presented. It will not "compute" with your indoctrination. It will never be "proven" in the lifespan of our sun, but that does not make it wrong or impossible.