Is the universe truly expanding, or collapsing?

How is it truly shown that the universe is expanding? Would redshift
not be equally evident while the universe was collapsing, as matter
closer to the center of the universe would decelerate more quickly, ie.
accelerate away from outer matter?

wrote in message
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How is it truly shown that the universe is expanding? Would redshift
not be equally evident while the universe was collapsing, as matter
closer to the center of the universe would decelerate more quickly, ie.
accelerate away from outer matter?


No, you would see blueshift from those objects that were moving towards us
from the other side of the point that everything was moving towards.

wrote:
How is it truly shown that the universe is expanding? Would redshift
not be equally evident while the universe was collapsing, as matter
closer to the center of the universe would decelerate more quickly, ie.
accelerate away from outer matter?


'Tis true, so I've heard, that when falling into a black hole,
everything would appear to be rushing away from you!

Double-A

Indeed, so do we see red shift that far beyond whatever everything is
moving towards?

Those objects further than us from BB will still be moving away faster
than we are. Objects nearer the BB than we are will be decelerating
away from us. And objects on the other side of BB will still be moving
away from us. Correct me if I'm wrong on those.

So assuming no dark matter, in a universal state of deceleration, all
bodies will be in redshift.

wrote in news:1125189934.604367.267250
@f14g2000cwb.googlegroups.com:

Those objects further than us from BB will still be moving away faster
than we are. Objects nearer the BB than we are will be decelerating
away from us. And objects on the other side of BB will still be moving
away from us. Correct me if I'm wrong on those.

So assuming no dark matter, in a universal state of deceleration, all
bodies will be in redshift.



No one's mentioned this yet, so I will. The universe is not expanding
from a given point; or if contracting, contracting to a given point.

There is no "other side of BB".

The universe is expanding from all points within simultaneously.

There was an excellent article in Scientific American back in the
March 2005 issue titled, "Misconceptions About The Big Bang."
Fortunately the article is on their website:
http://www.scientificamerican.com/ar...D=1&articleID=
0009F0CA-C523-1213-852383414B7F0147

or if that's too long: http://tinyurl.com/4hw24

Brian
--
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism

Seismic FAQ: http://www.skywise711.com/SeismicFAQ/SeismicFAQ.html

Sed quis custodiet ipsos Custodes?

Thank you, good points. I have been reading through those articles. I
have even more questions now

It is very interesting how new discoveries and theories are so
contradictory. For example acceleration of expansion partially
contradicts Hubble's Law which for quite some years was observed to be
true. Perhaps it is still true. It appears more as if our
observations are limited to a universally small frame, where
measurements could be a mere local variation caused by matter beyond
our view.

On new questions, how is it that recession speed can theoretically be
greater than the speed of light, but it can not overtake it? Doesn't
that contradict ideas of using light as a measure of
distance/expansion? Using red/blue shift as a measure of velocity?
Making samples in time of said velocity to deduce acceleration?

And in my last post I am not implying that the last three points are
not true, since they have been measured and shown to be true. It is
just difficult to understand how the special relativie theory holds
here.

wrote in news:1125200710.617110.301460
@f14g2000cwb.googlegroups.com:

Thank you, good points. I have been reading through those articles. I
have even more questions now

Which I think is a good thing. (questions, that is)


It is very interesting how new discoveries and theories are so
contradictory. For example acceleration of expansion partially
contradicts Hubble's Law which for quite some years was observed to be
true. Perhaps it is still true. It appears more as if our
observations are limited to a universally small frame, where
measurements could be a mere local variation caused by matter beyond
our view.

It's more along the lines of having more detailed information.
As our instruments get more and more precise, we can measure the
cosmos to greater detail.

Think of a picture of the Earth from space. If the view encompasses
the whole globe, about all you can make out is the clouds, continents,
and oceans. As you zoom further in you begin to see more and more
detail. As you gain more detail you can refine your theories or
discover things that contradict your previous theories.

One example I can thnk of is Titan. When Voyager flew by Saturn
the images showed an orange ball. We couldn't see the surface.
We had to make conjectures based on the known data on what the
surface of Titan was like. AS time went by, ground based telescopes
start studying Titan in the infrared where it's atmosphere was
less opaque. We started detecting surface features and other
spectroscopic data.

Then comes the Cassini mission which dropped the Huygens probe
onto Titan. Based on the previous data it was considered likely
that Huygens might land in a sea or ocean of liquid methane. But
Huygens landed on a hard surface, maybe a slush. The latest data
since more flyby's of Cassini is that there are no liquid lakes
or seas.

So to summarize, it's entirely possible that as more data is
gathered it will contradict the theories based on previous data.


On new questions, how is it that recession speed can theoretically be
greater than the speed of light, but it can not overtake it? Doesn't
that contradict ideas of using light as a measure of
distance/expansion? Using red/blue shift as a measure of velocity?
Making samples in time of said velocity to deduce acceleration?

I don't know if this will make sense or not, cuz even though I
can understand it myself, I'm not always good at explaining things.
But basically, it's the fabric of space itself that is 'expanding'
faster than the speed of light. Light still travels at the same
speed it always has as it traverses this fabric.

Imagine you're walking on a giant balloon. You can only walk so fast.
But now imagine that this giant balloon is still inflating. If you
put two dots on a balloon and blow it up you'll see that the two
dots will move away form each other as the balloon expands. Now,
back to you walking on the giant balloon. Imagine that this balloon
is inflating so fast that the landmark that you are trying to
walk towards is expanding away from you faster than you can walk.
You can walk forever but you will never reach that landmark. And
so it is with the universe.

Hope that helps.

Brian
--
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism

Seismic FAQ: http://www.skywise711.com/SeismicFAQ/SeismicFAQ.html

Sed quis custodiet ipsos Custodes?

Thanks.

It's making some sense, though why does it apply at the universal level
and not at the local level? Like the fabric of space between Earth and
the Sun changing by a measurable amount? Is it just too small to be
measurable at this time? (I'm guessing yes)