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Question for Astronomy and Physics .....

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posted on Aug, 16 2006 @ 09:51 PM
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I have a curious question concerning facts accepted by current scientists in many fields of study.

One accepted truth is that the universe is expanding, and that rate of the expansion is accelerating.

The other fact is the relativity issue, (infinite mass issue among other issues), and speed of light travelling.


So here is the question:

If the gallaxies throughout the universe are accelerating, and are expected to continue to accelerate, then will gallaxies reach the speed of light as they travel through the universe, and if so, how will they look to observers who are not travelling at that speed? Would we see them?

I know it is a rather long and loaded question, with a follow-up, but what do you think?

Your input is appreciated in advance. Thank you.




posted on Aug, 17 2006 @ 12:45 AM
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from what i understand the universes expansion is continually slowing. it's supposed to be so close to the point where it will possibly stabilize at some point, due to the conflict between gravity and expansion, that we can't tell if we'll have a big crunch or a universal winter.



posted on Aug, 17 2006 @ 01:17 AM
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The critical model suggests that the matter in the universe is gradually slowing the rate of expansion towards zero, the current models shows that it will tend towards zero but never quite reach it, if it does then its likely to be a closed universe which will contract.

Technically , the hubble expansion (the expansion of space) can be faster than the spped of light, without the galaxies exceeding the speed (gravity stops teh galaxies expanding, but not the space between them)

math.ucr.edu...



posted on Aug, 17 2006 @ 01:35 AM
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so basically our current model shows that our expansion will slow exponentially, but it's not ever going to reach the limit of 0?

that's awesome! if that's the case, the universe may well be in existence for eternity!



posted on Aug, 17 2006 @ 01:45 AM
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This wiki post summarizes some of the possible fates of the universe
math.ucr.edu...

Most measurements show we have on or just above the critical density , that density of matter which is needed if teh univserse is expected to slow, but go on for ever, although some measurements have shown that we are below the critical density , and the univrse will eventually shrink.

THe majority of calcualtions and models though, agree with us being just on or very slightly above the critical density.



posted on Aug, 17 2006 @ 02:51 AM
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Originally posted by 25cents
from what i understand the universes expansion is continually slowing. it's supposed to be so close to the point where it will possibly stabilize at some point, due to the conflict between gravity and expansion, that we can't tell if we'll have a big crunch or a universal winter.


That's what I hear. The effects of the gravity of the leading edge pulling everything outward will weaken with the increase in distance.

Some say, I do also, that the Universe will set into a spin when this happens due to inertial dampening. If that occurs there ought to be some interesting qualities that appear in the Physics nature.



posted on Aug, 17 2006 @ 06:54 PM
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Hi guys,

According to some credible sources, the universe (and galaxies/matter within) is expanding and is accelerating. According to current models it will continue to accelerate. But, more than one variable still seems elusive. According to most scientists in various fields it should have already started to decelerate. Below are some source links.

Source/Link:

www.pbs.org...



External Source:
NOVA follows cosmologists trying to understand why the universe may be expanding at an accelerating rate.
The program:
- reviews data from two teams of astronomers that seem to indicate some unknown force that is causing the universe to expand faster and faster.
- explains that the astronomers are basing their theories on observations of type 1A supernovae, which are believed to be uniformly bright and thus can be used as reference points or "mileage markers" to measure the expansion of the universe.
- reviews the technical and logistical challenges involved in finding the right kind of supernova for further study.
- shows how astronomers painstakingly compare recent and months-old images of thousands of galaxies looking for minute changes in brightness that signal a supernova.
- notes that preliminary data indicate that the universe is accelerating in its expansion, not slowing down due to gravity as previously believed.


Source/Link:
en.wikipedia.org...



External Source
Main article: Ultimate fate of the universe
Depending on the average density of matter and energy in the universe, it will either keep on expanding forever or it will be gravitationally slowed down and will eventually collapse back on itself in a "Big Crunch". Currently the evidence suggests not only that there is insufficient mass/energy to cause a recollapse, but that the expansion of the universe seems to be accelerating and will accelerate for eternity (see accelerating universe). Other ideas of the fate of our universe include the Big Rip, the Big Freeze, and Heat death of the universe theory. For a more detailed discussion of other theories, see the ultimate fate of the universe.

Source/Link:
map.gsfc.nasa.gov...


The main attraction of the cosmological constant term is that it significantly improves the agreement between theory and observation. The most spectacular example of this is the recent effort to measure how much the expansion of the universe has changed in the last few billion years. Generically, the gravitational pull exerted by the matter in the universe slows the expansion imparted by the Big Bang. Very recently it has become practical for astronomers to observe very bright rare stars called supernova in an effort to measure how much the universal expansion has slowed over the last few billion years. Surprisingly, the results of these observations indicate that the universal expansion is speeding up, or accelerating! While these results should be considered preliminary, they raise the possibility that the universe contains a bizarre form of matter or energy that is, in effect, gravitationally repulsive. The cosmological constant is an example of this type of energy. Much work remains to elucidate this mystery!


So, if galaxies are accelerating, and will continue to do so, what will the galaxies look like as they approach the speed of light, or match it, from the view point of an observer who is not traveling at the speed of light? And, what will occur to an observer who is on a planet that naturally reaches such speeds? Are there laws in physics that should prevent planets, solar systems, and galaxies from reaching such speeds?

What other ramifications could exist if acceleration is continuous?



posted on Aug, 18 2006 @ 02:32 AM
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I'm not going to get into this to deep, but in the above, what about the drag coefficient produced from other galaxies?

I'd be curious to know how this can be overcome. I'm not stating that constant acceleration will not be achieved, though, because I've never been "out there" myself to know one way or the other.



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