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Author Topic: Are we at the edge of the Universe?  (Read 4130 times)

Offline lunar11

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Are we at the edge of the Universe?
« on: 29/12/2011 21:31:31 »
There is no 'centre of the Universe'. All space began from a singularity. Space is expanding just like a balloon been blown up.

When the Hubble telescope sees far in the distance a galaxy that is say near the edge of the Universe, it is highly redshifted and travelling at nearly the speed of light; then does that also mean that with respect to the galaxy in question, we too are near the edge of the Universe, and that we too are highly redshifted and travelling nearly at the speed of light?
« Last Edit: 29/12/2011 21:33:03 by lunar11 »


 

Offline burning

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Re: Are we at the edge of the Universe?
« Reply #1 on: 29/12/2011 21:58:52 »
Pretty much.  The main thing I would add is that because of the finite speed of light, everything seen a long way away is seen as it was a long time ago.  So an observer in that distant galaxy "now" (ignoring for the time being the whole can of worms surrounding that) would not be seeing the Milky Way galaxy as we know it but as a very young galaxy.
 

Offline CliffordK

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Re: Are we at the edge of the Universe?
« Reply #2 on: 30/12/2011 06:22:14 »
The Hubble can see a sphere, roughly 13.2 billion light years in radius, with the most distant object in all directions comprising of light emitted roughly 13 billion light years ago.  And, I believe the light emitted is highly red-shifted in all directions.

If you define the universe as all that can be seen from Earth, then the Earth would be in the center.

If you define the universe as all that exists, whether it is directly observable form Earth or not, then it would be difficult to determine where the middle is, or the exact shape of the universe.

One possible shape for the Universe would be a hollow sphere, in which the stellar matter would be rarefied in the middle from the big bang.  Or, perhaps concentrated in the middle from a re-collapse.

From Earth's vantage, the universe appears relatively homogenous in all directions.  Which might be one indication that we are unable to view the center of the universe.  But, it would also seem to indicate that we are equally unable to see the "edge" if there is a true edge.
 

Offline syhprum

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Re: Are we at the edge of the Universe?
« Reply #3 on: 30/12/2011 08:22:56 »
Hubble is always quoted as though it was the only high resolution telescope in existence, since its launch several Earth bound telescopes with larger apatures and equal resolution due to adaptic optics have been brought into service.
 

Offline Nizzle

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Re: Are we at the edge of the Universe?
« Reply #4 on: 30/12/2011 08:26:03 »
There is no 'centre of the Universe'. All space began from a singularity. Space is expanding just like a balloon been blown up.

The expanding universe
The universe is expanding just like a balloon in 4D spacetime.
If you want to keep the analogy, you'll have to consider this: The 2D surface of the balloon is our 3D universe. The "air" in the balloon is the past and the "air" surrounding the balloon is the future.
Since "new time" is created every second and the balloon is blown up, more air will be in the balloon (ie more time will be in the past).

If you look at the universe like this, we will always be at the edge of the universe (on the surface of the balloon) until we invent time travel.

Now, I've attached an image of this 4D balloon universe.
If you look at this attachment, you'll see that when we look at other galaxies, we're looking in the past. To keep the balloon analogy, we're looking through the "air inside the balloon". When a galaxy is farther away, we're looking farther into the past, which is represented by a longer red line. (pun: more redshift)
The age of the Universe would be the radius of the circle in my diagram.

Since we cannot (yet) look in the future, we can only look inwards on the balloon, and not outwards. By the way, if we could look into the future and did look outwards of the balloon, there would be nothing to see according to me :)



The observable Universe
So when we follow this 4D balloon, we can distinguish the real universe from the observable universe according to the second diagram.
The thin red line is the age of the universe, otherwise known as the time between the big bang and 'now'.
The thick red line should have the same length as the thin red line if I had a better drawing skills, but let's say it does have the same length.
The thick red line represents the distance in space you can travel at the speed of light during the same period of time as the thin red line.
Now, photons and everything else that moves in our universe will move on the 2D surface of the balloon (our 3D space).
Since both red lines are just as long and thus represent the same length of time we will only see the universe on the balloon surface around Us for which the photons have had the time to reach us. Everything that's on the surface of the balloon in the grey area, is not part of the observable universe.
Now, if time goes on, the red line between the big bang and us will become longer, and so the distance on the surface that photons will be able to travel will also become longer.
Depending on the curvature of the balloon surface, the observable universe will grow or shrink.



Note that I'm not a physicist and that this is just how I interpret the universe, so now I'm waiting for the true physics experts to tell me how wrong I am :)
« Last Edit: 30/12/2011 10:07:55 by Nizzle »
 

Offline lightspeed301

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Re: Are we at the edge of the Universe?
« Reply #5 on: 04/01/2012 00:50:42 »
Are we at the edge of the universe?

This might actually be the case, IMHO. The universe might very well be expanding INWARD. In all directions we see back to about 350 million years after the big bang when the universe became transparent. We are looking back at a shell that surrounds us on all sides.

My understanding is that inflation expanded the universe to something like the size of our own galaxy in just a few Plank Times. Thats when most, if not all of the four forces of nature precipitated into existence. Accordingly, it looks like all the matter in the universe was in existence in less then one billion years.

So. How in the hell did our material galaxy get 15 BILLION light years ahead of any of it? If all material already existed at one billion years, and nothing moved faster then light after that.

« Last Edit: 04/01/2012 00:58:07 by lightspeed301 »
 

Offline lightspeed301

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Re: Are we at the edge of the Universe?
« Reply #6 on: 04/01/2012 01:14:01 »
PS

I believe Susskind postulate the universe could be something like a holograph. He's the guy who won the argument against Hawking radiation that Hawking proposed would evaporate black holes.

Specifically, we can not observe anything actually passing the event horizon of the BH because general relativity slows the time of the object approaching the event horizon to effectively zero.  I don't know how this accommodates the fact event horizons expand.

However I have always believed Black Holes are hollow due to conservation of angular momentum.  Michio Kaku [?] recently surmised Black Holes include matter in a sort of donut shape near the event horizon for the same reason.
 

Offline CliffordK

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Re: Are we at the edge of the Universe?
« Reply #7 on: 04/01/2012 01:21:53 »
I think I had asked (perhaps in a different post).

If we see light that is the equivalent of 13.2 billion light years away in all directions (i.e.  A sphere 26.4 light years in diameter), how could that sphere have formed within the first billion years of the formation of the Universe?

Part of the answer is that the source where the light was emitted wasn't necessarily 13.2 billion lightyears away.  The universe could have been much smaller, but the space between here and there would have expanded so that the light has traveled the equivalent of 13.2 billion lightyears to get to Earth.

Our view of the most distant visible parts of the universe is so obsolete, that we have absolutely no idea what is happening now, or whether there is continued expansion or contraction.
 

Offline Nizzle

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Re: Are we at the edge of the Universe?
« Reply #8 on: 04/01/2012 05:36:23 »
Our view of the most distant visible parts of the universe is so obsolete, that we have absolutely no idea what is happening now, or whether there is continued expansion or contraction.

I agree. It's proven that expansion is accelerating with the type Ia supernovae, but that's based on measurements within the observable universe only. Who's to say that accelerating expansion is not a 'local' phenomenon??
 

Offline happeninD

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Re: Are we at the edge of the Universe?
« Reply #9 on: 22/01/2012 04:04:36 »
Nizzle -- I appreciate your visuals aids which assist in clarifying your point. I do have a few questions, however, how do we know our position within this "balloon of space"? Are we at the edge, or more precisely, are we the youngest part of the universe? Are we looking to the past, or into the future? Personally, I have a difficult time believing that we can precisely fixate our position in a place we barely understand. Also, if the universe is a balloon, will we ever be able to observe the opposite side of the Big Bang?  B)
 

Offline CPT ArkAngel

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Re: Are we at the edge of the Universe?
« Reply #10 on: 22/01/2012 04:54:50 »
There is no proof that there is an acceleration of the expansion. The measurements show acceleration only if the standard spacetime expansion cosmological model is right. No true acceleration has been measured, only distances. Since Hubble telescope, many observations show discrepancies with the standard cosmological model and i predict more and more to come...

Beware of alleged proofs that are truly theoretical... There is so many in the standard model, particularly in particles and cosmological models. Many conclusions need a unified theory, which we don't have ;).
« Last Edit: 22/01/2012 05:03:55 by CPT ArkAngel »
 

Offline CliffordK

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Re: Are we at the edge of the Universe?
« Reply #11 on: 22/01/2012 09:34:10 »
One thing to keep in mind.

Current estimates are that the MilkyWay is moving at about 550,000 m/s with respect to cosmic microwave background radiation. or just slightly more than 1/1000 the speed of light.

So far, we have not identified a rest-frame in the universe, or our absolute speed with respect to the rest frame.  However,if we take the 550,000 m/s, then we are actually moving relatively slowly, an thus we might, in fact, be somewhere near the the middle of the universe. 

I assume one could identify stars or galaxies that are sufficiently red-shifted that they would essentially be at rest with respect to the CMBR.
 

Offline Soul Surfer

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Re: Are we at the edge of the Universe?
« Reply #12 on: 22/01/2012 10:17:31 »
considerable efforts have gone into the determination of local relative velocities in galaxy groups and clusters and estimating the cluster velocities with respect to the cosmic microwave background as well as measuring their true positions in space and the expansion rate of space itself (red shift).  It was from these that the acceleration of expansion was detected.  The absolute (relative to CMB) velocities of galaxies are very similar to our velocity that is around 1/1000 that of light i.e. there are no high velocity galaxies.
 

Offline happeninD

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Re: Are we at the edge of the Universe?
« Reply #13 on: 23/01/2012 12:54:54 »
Thanks for your response and help to answering my questions.  If the universe is theoretically a balloon, is light pushing the universe out further and further? If, as you say, there are no high velocity galaxies, wouldn't that be the only possible case? If there is an edge, would the constant flow of light rays collect at it's edge and create a loud (bright) cosmic background? I'm very sorry for my silly questions, but I don't have a lot of background in astronomy other than what's been read in the my free time. Anyways, thanks for your assistance.  :o)
 

Offline CliffordK

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Re: Are we at the edge of the Universe?
« Reply #14 on: 23/01/2012 19:54:21 »
I don't think there is an edge like a mirror, per-se.  So, the light produced by the stars would just shoot off into empty space.  Obviously we can only perceive light coming from one direction from the stars.  It is likely that an "edge" would be perceived as a slow thinning of matter, until there is none.

If there are, in fact, objects traveling at the speed of light, it may be weird as all their light may be perceived from behind them, and not in front of them.

Nonetheless, we can only perceive light directed at Earth.
 

Offline Soul Surfer

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Re: Are we at the edge of the Universe?
« Reply #15 on: 23/01/2012 23:07:57 »
Clifford you must remember that these objects are not travelling at the speed of light it is the space between them and you the distant observer that is growing at the speed of light as I explained above observations show that galaxies are all travelling at speeds of the order of a few hundred miles a second with respect to other local galaxies and the cosmic microwave background.
 

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Re: Are we at the edge of the Universe?
« Reply #15 on: 23/01/2012 23:07:57 »

 

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