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Offline Ozanners

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Expansion of the universe...
« on: 18/05/2006 01:47:03 »
I was pondering the other day my take on the supposed expansion of the universe, is it possible that EVERYTHING is inflating? I always thought of expansion meaning the universe and it's constituent parts were expanding out beyond their current boundaries in a fairly linear but multi dimensional fashion. But then I thought could everything be simply getting bigger, would we know, if everything was expanding relative to everything else, ie the measuring devices were enlarging as much as the reality they are measuring and therefore show no measurable difference. Does this fit in with any current theories? How might this relate to red shift or does red shift just rule out this thinking straight away?

What do you think, have I contradicted myself?

I'd be interested to hear your views on this.

Tom.


 

another_someone

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Re: Expansion of the universe...
« Reply #1 on: 18/05/2006 02:24:41 »
quote:
Originally posted by Ozanners

I was pondering the other day my take on the supposed expansion of the universe, is it possible that EVERYTHING is inflating? I always thought of expansion meaning the universe and it's constituent parts were expanding out beyond their current boundaries in a fairly linear but multi dimensional fashion. But then I thought could everything be simply getting bigger, would we know, if everything was expanding relative to everything else, ie the measuring devices were enlarging as much as the reality they are measuring and therefore show no measurable difference. Does this fit in with any current theories? How might this relate to red shift or does red shift just rule out this thinking straight away?

What do you think, have I contradicted myself?

I'd be interested to hear your views on this.

Tom.




My own view is that the contrary is true.

When we observe the expansion of the universe, we are not observing the increasing size of the objects therein, but rather the increasing size of the spaces between the objects.  Thus, one might say that this would be indistinguishable from the objects themselves getting smaller, thus the spaces between the objects appearing to get bigger in relation to the objects themselves.

Another possibility could be that units of time are getting smaller (i.e. it takes more time to travel from one part of the universe to another, including for light to travel from one place to another, and so gives the appearance of the universe itself getting bigger).



George
« Last Edit: 18/05/2006 02:42:50 by another_someone »
 

Offline PrajnaDhyana

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Re: Expansion of the universe...
« Reply #2 on: 18/05/2006 03:07:23 »
Tom, you are exactly right in this.  In fact, I posted something on this exact thing in a different thread earlier today. (http://www.thenakedscientists.com/forum/topic.asp?TOPIC_ID=4245)

Astronomers where amazed to find data showed that some galaxies where moving away from us faster than the speed of light.  Knowing that this wasn't possible they investigated more to find out what was causing it to appear that way.  The culprit turned out to be the expansion of the universe.  
As the light was traveling towards the Earth, the distance it had to travel was getting larger and larger as the universe expanded.  Not only were the galaxies traveling away from us with their own speed, but the actual space they were in was getting farther and father away due to the expansion of space between the galaxy and us.  Think of two dots drawn on an uninflated balloon.  As you blow up the balloon and the rubber stretches, the dots get further apart, even though they are stationary on the surface of the balloon.
The Combination of the speed the galaxies were moving through space with the "speed" of the Universe's expansion produced the illusion that the galaxies were traveling faster than light.  An example is an airplane flying in the jet stream.  The plane is moving at 525 mile per hour on it's own.  But the air in which it is flying is also moving at 200 mph.  So even thought the plane is only moving at 525mph relative to the air around it, compared to the ground it's moving at 725mph, or faster than the speed of sound.  (I've actually done this on a flight from Tokyo to Seattle.)

(Red shifting is caused by the motion of the galaxies in relation to us, and not so much by the expansion of the Universe)
« Last Edit: 18/05/2006 03:14:28 by PrajnaDhyana »
 

Offline ukmicky

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Expansion of the universe...
« Reply #3 on: 24/05/2007 02:14:08 »
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(Red shifting is caused by the motion of the galaxies in relation to us, and not so much by the expansion of the Universe)

Before i say your , and incase i'm not understanding what you mean can you explain exactly what you mean.
 

Offline that mad man

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Expansion of the universe...
« Reply #4 on: 24/05/2007 15:24:52 »
Darn, confused again!

The last time I listened to a program on the cosmos the astronomer, Heather Cooper, stated that the universe is infinite and unbounded so is that true?

If it is true then the universe would have no centre or edge so can there be any expansion?

Bee

 

Offline Batroost

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Expansion of the universe...
« Reply #5 on: 25/05/2007 22:35:40 »
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(Red shifting is caused by the motion of the galaxies in relation to us, and not so much by the expansion of the Universe)

There's more than one red-shift.

Yes, you can measure a red-shift that seems to be due to movement away from the observer.

But there is also a longer-term red shift that is most easily attributed to an overall expansion of the universe - so the cosmic bacground radiation is redshifted way-down to microwave frequencies.

Then there is also gravitational redshift, experienced by light as it climbs out of a gravity field; a strong enough effect to be measureable (with accurate instruments) even in tall buildings.
 

Offline @@

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Expansion of the universe...
« Reply #6 on: 27/05/2007 22:03:32 »
I was pondering the other day my take on the supposed expansion of the universe, is it possible that EVERYTHING is inflating?
Tom.


i dont think so, if this were the case it would mean everything was taking on more mass, where would that extra mass be coming from?
 

another_someone

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Expansion of the universe...
« Reply #7 on: 27/05/2007 22:15:39 »
I was pondering the other day my take on the supposed expansion of the universe, is it possible that EVERYTHING is inflating?
Tom.


i dont think so, if this were the case it would mean everything was taking on more mass, where would that extra mass be coming from?

I did indicate the reasons why I thought the proposal unlikely, but I am not sure why it should effect mass (would an increase in space actually need to have any impact on mass?), but even if mass is changing, would this be a problem?  Mass can be created from energy, so clearly the old notion of conservation of mass in not inviolate.  It may well be that time, like energy, might be converted to mass (this is not to say that I have any reason to believe this is so, only that I see no reason to dismiss it as impossible - after all, Newton would never have imagined that we could create mass from kinetic energy).
 

Offline Brex

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Expansion of the universe...
« Reply #8 on: 27/06/2007 12:45:59 »
A loop of cotton on the surface of water will be pulled out to form a circle if the surface tension is reduced within the loop and if that loop could expand it would do so whilst surface tensions inside and outside remained unequal. Similar logic applies to the balloon analogy to the curvature of our universe; the curved surface area expands due to pressure differences inside and outside of the closed area. The universe is curved in all directions within a fourth dimension and so must similarly form an ‘enclosure’ within that dimension. Pressure differences within and without that enclosure could be causing the universe to expand rather than inertia restrained by gravity after the initial inflation. I have no doubt that this has been considered but why is it not widely expressed?
 

Offline safertr

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Expansion of the universe...
« Reply #9 on: 05/07/2007 14:58:45 »
What is the Universe expanding into?
newbielink:http://www.astro.ucla.edu/~wright/cosmology_faq.html [nonactive]
This question is based on the ever popular misconception that the Universe is some curved object embedded in a higher dimensional space, and that the Universe is expanding into this space. This misconception is probably fostered by the balloon analogy which shows a 2-D spherical model of the Universe expanding in a 3-D space. While it is possible to think of the Universe this way, it is not necessary, and there is nothing whatsoever that we have measured or can measure that will show us anything about the larger space. Everything that we measure is within the Universe, and we see no edge or boundary or center of expansion. Thus the Universe is not expanding into anything that we can see, and this is not a profitable thing to think about. Just as Dali's Corpus Hypercubicus is just a 2-D picture of a 3-D object that represents the surface of a 4-D cube, remember that the balloon analogy is just a 2-D picture of a 3-D situation that is supposed to help you think about a curved 3-D space, but it does not mean that there is really a 4-D space that the Universe is expanding into.
newbielink:http://www.click2finding.com/click2.aspx?pr=Science/Physics/Particle/ [nonactive]
 

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Expansion of the universe...
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