universe expansion conundrum

[crabhaver]

How is it possible to see light from stars that are 13.2 or so billion light years away? If we started at the same point and matter can't travel the speed of light how has the initial light of stars 13.2 billion years ago not passed us. We would have to be very near where we are now 200,000,000 years after the big bang in order for light that old to reach us and not already have passed us. Unless we started inflation near the speed of light and the net speed of light is so low that it could take that long, however, there would still be a limit. In addition wouldn't that make the "Big Rip" theory impossible. We would already be breaking up. Since the universe is accelerating still and in order to see the light of a star 13.2 billion light years away, and space is inflating at close to the speed of light, then the stars must be nearly 26.4 billion light years away now, or they were 6.6 billion light years away when the light was emitted and scientists are just doing the math and the star is 13.2 billion light years away, but the light was emitted 6.6 billion years ago and we guestimate the distance the star would be now. the star has traveled immense distances beyond 13.2 billion light years away since the light we are now seeing from it was emitted. What makes this more confusing is how can we see light or CMBR 300,000 years after the big bang. We would have to almost instantaneously reposition to where we are now, or be traveling (inflating)over 99% the speed of light. This also applies even if the earth and the other object our heading away from eachother netting a speed close to the speed of light. Sorry for being so verbose. THanks

[John Connellan]

unless we started inflation near the speed of light and the net speed of light is so low that it could take that long

No, it actually started expanding much faster than the speed of light. Does this help now?

[2inquisitive]

And don't forget, crabhaver, current theory states the speed of light is invarent. That
leads to the velocity addition law, which says you can't add or subtract the velocity
of the emitting object from the speed of light. That means the early light is still traveling at "c", only the wavelength is streched (red shifted) and the object was
13.2 billion lyrs distant from us when the light was emitted. Due to the observation
that such distant objects are receeding from us at a speed greater than the speed of light due to the accelerating expansion, such an object is thought to be something
like 50 billion lyrs from us NOW. Confusing, isn't it?

[crabhaver]

Thanks for the replies john and 2inquisitive. I have a couple of questions though. I didn't think matter could travel faster than the speed of light. If it can't, the universe would have only expanded until the energy turned into matter, right? How long would that have been, a few hundred thousand years after The Big Bang? And, relativistically speaking, as 2inquisitive put it, the speed of light is invarient. How do relativistic theorists put this faster than "c" expansion into their theory. Is the universe propelling the matter like a floating bottle on a wave. If so, you still have the initial problem once again. I understand what you are saying 2inquis. bout the speed of light not being able to net different speeds. Thanks. About the universe expanding faster than the speed of light, First, how do we see the light from stars that due to universe expansion are traveling faster than "c". And two, how could a theory like "The Big Rip" take hold if we are already traveling at breaking up speeds. How can light be bound by the velocity addition law, but matter isn't. If a star is 50 billion light years from us now then the matter is traveling faster than "c" relative to us. It's very confusing to me. I'm going to become religious, maybe then I'll c the light, instead of trying to b c. Very loose attempts at being punny. Thanks again.

[2inquisitive]

crabhaver, I can't explain it to you so it all fits together, because it doesn't to me. I
read a lot of the new cosmology papers published and I still cannot get a clear understanding of how it all fits together. There are many theories of the early universe,
but all seem to have some unresolved problems. Some popular theories of the past
have either been dropped from consideration by recient observation and data collection
or have been modified. The Big Bang and inflation is still the leading theory, but there
are different models of the Big Bang and different models of Inflation.
I will try to help a little concerning your questions. Keep in mind, I am not a cosmologist, so I could very well be incorrect. My understanding concerning FTL
expansion is, even though the light emitting galaxies are receeding from us faster than
light, the light emitted still travels at "c" in relation to us and we can still detect it,
although sometimes red shifted into the near-infrared spectrum. Special Relativity is
said not to apply at these cosmological distances and should be only be used in our
cosmic neighborhood by some cosmologists. Others say the expansion is caused by
an increase in the volume of space itself and SR is not affected because the expansion
does not reflect a true velocity between two objects. The nature of Dark Energy has
not been determined yet, so whether the expansion is due to Dark Energy with repulsive-gravity properties or to the creation of new space within the vacuum has not
been settled. Mathematical calculations using QM's zero-point energy has ruled that
energy out as the source of the expansion because it would be much too strong causing the universe to fly apart many millions of years ago. From my understanding,
the "Big Rip" is supposed to be a result of entropy, the cooling of the universe to near
0 degrees as it expands. At 0 degrees, all movement stops and atoms lose their nuclear bonds, disintergrating. In reference to the 50 billion lyr figure, some papers
have been published stating that some objects are receeding from us faster than light
AND ALWAYS HAVE BEEN. As i said, confusing.

[Vaccum Pony]

2inquisitive, you said:

Mathematical calculations using QM's zero-point energy has ruled that
energy out as the source of the expansion because it would be much too strong causing the universe to fly apart many millions of years ago.


Do you have any links about this? I was under the assumption that this was still the leading idea about what is causing inflation.

V.P.

[John Connellan]

Crabhaver: Universal expansion does not contradict SR. The matter is not moving but rather space is expanding giving the appearance that the stars are receding from us at great speed. Think of space like a the surface of a balloon. Draw 2 points on the ballon to indicate 2 stars. Blow up the balloon (i.e. expansion) and the dots get further away from each other and the further away they are, the faster they move away.

This second point explains how we can see light from stars. Most of the stars we see in the night sky are NOT receding at c. These high speeds really only apply to galaxies very far away. At the edge of our observable universe are thousands of galaxies which are very much red-shifted because of their recession.

[2inquisitive]

I have not found the paper I read about vacuum energy as being discounted as the
source of the expansion. I built a new computer a couple of months ago and did not
save my old "favorites." I will look some more over time, but I haven't a clue to the
title of the paper or in which publication it was in. I did, however, find the following
article in the popular science publication "Science." The conformation of Dark Energy
as being the mechanism behind expansion won the "breakthrough of the year" in their
magazine.
"In 2003, new evidence cemented the bizarre idea that the universe is made mostly of mysterious "dark matter," being stretched apart by an unknown force called "dark energy." This set of discoveries claims top honors as the Breakthrough of the Year, named by Science and its publisher, AAAS, the nonprofit science society.

These insights into our "dark" universe plus nine other research advances make up Science's top ten scientific developments in 2003, chosen for their profound implications for society and the advancement of science. The Top Ten list appears in the journal's 19 December issue.

This year, information from the Wilkinson Microwave Anisotropy Probe (WMAP) satellite and the Sloan Digital Sky Survey (SDSS) telescopes confirmed some of cosmologists' strangest proposals about the fate of the universe.

"The implications of these discoveries about the universe are truly stunning. Cosmologists have been trying for years to confirm the hypothesis of a dark universe. Science is glad to recognize their success in this effort as the Breakthrough of the Year for 2003," said Don Kennedy, Editor-in-Chief of Science.

Those proposals entered the spotlight five years earlier, when Science's 1998 Breakthrough of the Year honored the discovery that the universe was expanding. Such an expansion would likely be driven by a "dark energy" that counters the effects of gravity. At the time, however, many cosmologists were wary of this strange idea.

Their doubts were dispelled in 2003. WMAP took the most detailed picture ever of the cosmic microwave background -- the light emitted by the universe during the first instant of its existence. By analyzing patterns in this light, researchers concluded that the universe is only 4 percent ordinary matter. Twenty-three percent is dark matter, which astrophysicists believe is made up of a currently unknown particle. The remainder, 73 percent, is dark energy.

WMAP also nailed down other basic properties of the universe, including its age (13.7 billion years old), expansion rate and density.

The SDSS, an effort to map out a million galaxies, also made major contribution to our understanding of the universe this year. By analyzing how galaxies are spread out through space, the researchers can see if the galaxies are being pulled apart by dark energy or pushed together by gravity.

In October, the SDSS team reported its analysis of the first quarter-million galaxies. Its conclusion was the same as WMAP's: the universe is dominated by dark energy."

[2inquisitive]

I do have a link to the published paper the above article was addressing. Here is link
to the pdf file. A word of caution; the paper contains many charts with color graphics
and takes 3 or 4 minutes to download on dialup.
http://xxx.lanl.gov/PS_cache/astro-ph/pdf/0310/0310723.pdf

[crabhaver]

even though the light emitting galaxies are receeding from us faster than
light, the light emitted still travels at "c" in relation to us and we can still detect it

I follow what you are saying, a part of special relativity. However, here is an example from an article that contradicts that.
"Loeb, a theoretical astrophysicist at the Harvard-Smithsonian Center for Astrophysics...Loeb says, galaxies will recede at the speed of light, making it impossible for their light -- or any other radiation or information -- to traverse the cosmos to our home in the Milky Way Galaxy. Any given source accelerates away from us and eventually reaches a speed larger than the speed of light so that photons emitted from it cannot catch up with the cosmic expansion, relative to us, he said." http://www.space.com/scienceastronomy/universe_end_011212.html.

Concerning "The Big Rip Theory". I think what they are saying is the dark energy will get so powerful that it will rip the matter apart before entropy occurs and matter turns into Bose Einstein Condensation. Here is an article link:
http://www.betterhumans.com/News/news.aspx?articleID=2003-03-06-4

whether it is through expansion of space around us like a baloon or our own speed, we are still traveling at speeds near or greater "c", right? I guess since it's all still speculation, which theories are most reliable. Is red shift the most proven method of measuring distances? Do they agree with supernova measurements? It's difficult to see how there wouldn't be a conflict with SR. Maybe my conflicts are from taking incompatible info from different theories and trying to coalesce it into one.

I apologize if I'm frustrating you guys. I know I sound like a five year old, with question after question, however, I have become extremely facinated with astrophysics, and cosmology. Thus, I appreciate you all being so patient. Thanks again.

[2inquisitive]

The article you cited was from 2001, by Abraham Loeb, a THEORETICAL astophysicist.
From the artical:
"
Eventually, Loeb says, galaxies will recede at the speed of light, making it impossible for their light -- or any other radiation or information -- to traverse the cosmos to our home in the Milky Way Galaxy.

"Any given source accelerates away from us and eventually reaches a speed larger than the speed of light so that photons emitted from it cannot catch up with the cosmic expansion, relative to us," he said.

Already, galaxies more than 6 or 7 billion light-years away are beyond contact, Loeb figures. Such galaxies, measured by astronomers to have a redshift of 2 or more, will not be able to transmit any signal to us in the future due to the accelerated expansion of the universe.

"Suppose there are extraterrestrial civilizations in these galaxies," Loeb said in a telephone interview. "If we send a signal to them now, they will never see it."

Seems he has been proven incorrect. There have been many galaxies studied at
red shifts beyond 2 now. The studies are based on direct observation and data
collection, overshadowing his theories. The latest Hubble Ultra Deep Space Field
has revealed a galaxy with a red shift of 12. They are still confirming this red shift,
but others have been confirmed at red shifts up to z=6.3 and beyond by both ground
based and Hubble views. Cosmology is a rapidly evolving field and any theories over
a few months old may have been shown incorrect already. Many others have been modified from their textbook descriptions. As I have mentioned before, there are many
different theories, even concerning Inflation. WMAP and SDSS, based on observation
and data collection, are narrowing the field. There are winners still in contention and
losers that are dropped from contention.
The second article you linked to was from a theory published in "New Scientist." That
publication doesn't have as strict of an acceptance policy as some of the more highly
respected publications. New data suggest, not proves, that the expansion will continue
at a steady rate of acceleration. What is meant by this is that expansion is increasing
at an ever increasing rate, but the rate itself is linear. For that theory to be correct,
the rate of the increase itself would have to increase, if that makes any sense to you!
In other words, the rate of expansion would be on a curve instead of a straight line
going up a graph at an angle. There have been no indications of that, but it doesn't
make it impossible, just unsupported at present. I don't think it is a mainstream view
by most cosmologists. The results from WMAP and SDSS are observation and data,
not speculation. Speculation comes from unsupported theories. WMAP and SDSS do
not offer theories, just data to see which theories by others offer the "best fit."

[crabhaver]

OK, I am getting there. I have one more question which seems to put me back at the beginning. If Loeb is wrong and the light still travels to us at "c" no matter how fast we expand past the speed of light, the light will catch us at 186,000m/s, once again putting us in the position of light from 13.2 billion years ago should have passed us if SR hasn't broken down at those distances. If after the big bang we went faster than the speed of light, then we were propelled away from the incoming light, out pacing it which means SR didn't apply at this point. that still seems to bring me back to my same question. Bottom line: SR couldn't have applied after the big bang because the light would have passed us already. In addition, SR must have kicked in and still be active now in order for light to have caught up to us, right? If you wouldn't mind please sum up what theory you follow for light reaching us now, that is 13.2 billion years old.

Thanks

[2inquisitive]

I don't have any certain theory I follow, I just review some of the latest observations
and data gathered. Some older theories are being revised and some new ones proposed. If you read the link to the actual paper published in my link above, it will
give you some insight into the complexities of the data collected. I know of no one
theory that can explain all the data. Some conclusions have been drawn, but the
overall picture is still lacking in detail. Many universities and scientists in different
fields have been involved in these studies. The link above will list many of them.
I will try to post a copy and paste from the conclusions and the end of the paper,
but it is from pdf and in two colums, so I don't know how to do a good job.
The cosmology community has now established the ex-
istence of dark matter, dark energy and near-scale invari-
ant seed fluctuations. Yet we do not know why they exist
or the physics responsible for generating them. Indeed,
it is striking that standard model physics fails to explain
any of the four ingredients of the cosmic matter budget:
it gives too small CP-violation to explain baryogenesis,
does not produce dark matter particles, does not produce
dark energy at the observed level and fails to explain the
small yet non-zero neutrino masses.
Fortunately, upcoming measurements will provide
much needed guidance for tackling these issues: con-
straining dark matter properties (temperature, viscosity,
interactions, etc.), dark energy properties (density evo-
lution, clustering), neutrino properties (with galaxy and
cmb lensing potentially sensitivity down to the experi-
mental mass limits ∼ 0.05 eV [137–139]) and seed fluc-
tuation properties (model-independent measurements of
their power spectrum [127])
nautics and Space Administration, the National Sci-
ence Foundation, the U.S. Department of Energy, the
Japanese Monbukagakusho, and the Max Planck Soci-
ety. The SDSS Web site is http://www.sdss.org/.
The SDSS is managed by the Astrophysical Re-
search Consortium (ARC) for the Participating Institu-
tions. The Participating Institutions are The Univer-
sity of Chicago, Fermilab, the Institute for Advanced
Study, the Japan Participation Group, The Johns Hop-
kins University, Los Alamos National Laboratory, the
Max-Planck-Institute for Astronomy (MPIA), the Max-
Planck-Institute for Astrophysics (MPA), New Mexico
State University, University of Pittsburgh, Princeton
University, the United States Naval Observatory, and the
University of Washington.
MT was supported by NSF grants AST-0071213 &
AST-0134999, NASA grants NAG5-9194 & NAG5-11099
and fellowships from the David and Lucile Packard Foun-
Sorry for the confusing text!

[John Connellan]

If you wouldn't mind please sum up what theory you follow for light reaching us now, that is 13.2 billion years old.
Thanks

Who's saying that we are seeing light which is 13.2 billion years old?

[2inquisitive]

John, the ESO for one. Here is a cut and paste to an article you may have missed:
"Named Abell 1835 IR1916, the newly discovered galaxy has a redshift of 10 [3] and is located about 13,230 million light-years away. It is therefore seen at a time when the Universe was merely 470 million years young, that is, barely 3 percent of its current age.

This primeval galaxy appears to be ten thousand times less massive than our Galaxy, the Milky Way. It might well be among the first class of objects which put an end to the Dark Ages of the Universe."

http://www.eso.org/outreach/press-rel/pr-2004/pr-04-04.html

[John Connellan]

Wow ,thats brand new news! So our theories for an observable universe and unobservable universe could be coming to an end then???

[crabhaver]

Hey John, 2inq. is refering to the same galaxy I am; however, as long as you are in the same realm of age; 9, 10, 11, 12 billion years, the exact # 13.2 billion is an arbitrary facet to my foundational question.

[Pete]

So our theories for an observable universe and unobservable universe could be coming to an end then???

How does that follow?

[John Connellan]

How does that follow?

It doesn't :D

I thought about it some more and realised that there are objects even further away than that which cannot yet be seen.

We ARE coming ever closer to observing the boundary of our observable universe however which is set a little bit farther than that galaxy.

[crabhaver]

What do you think about this?

"At the beginning, the 'spot' of the Big Bang embraced the entire universe. Consequently, every point in the current universe was once at, and therefore participated in, the Big Bang.

Depending upon the phase of the expansion, the size of the universe [meaning its radius and the average distance between objects (such as galaxies)] is proportional to the 1/2 or 2/3 power of the time, while the furthest distance from which light emitted during the Big Bang can reach us [the event horizon] is proportional to the time [ct]. Therefore, as time advances, the event horizon encloses a larger and larger fraction [as well as absolute volume] of the universe. That is, the distance to the event horizon grows proportionally faster than the universe itself.

This means that, as time goes on, the event horizon continually expands to encompass new points in the universe that had, up to that time, been beyond the event horizon. Therefore, there continues to be a supply of new points whose light generated in the Big Bang is now just able to reach us.

Of course, you are correct that light already received at an earlier time from points lying closer in than the current event horizon has already passed by, never to be seen again on earth [Until, perhaps, the event horizon has grown so large that it encompasses the given point a second time. In other words, until the light emitted toward earth has travelled past the earth and made a full circuit of the universe and returned to the earth. Recall that the universe is modelled as a sphere.]"
-Warren F. Davis, Ph.D., Physics, MIT

also thanks for the links 2inq.
Is the VLT using its interferometry yet?
Is a redshift of 2 supposed to be equivalent to the velocity of "c" from one object traveling in the opposite direction relative to us?

[2inquisitive]

quote:
"Is the VLT using its interferometry yet?
Is a redshift of 2 supposed to be equivalent to the velocity of "c" from one object traveling in the opposite direction relative to us?"
-----------------------------------------------------------------------------

Yes, I am quite sure the galaxie discovered with the red shift of 10 was done using
that method (the interferometry). All four telescopes became operational in 2001.
Interferometry is a method of using light gathered by all four 8.2 meter telescopes
to get the same resolution as a much larger telescope, hence the ability, along with
adaptive optics, to resolve galaxies at those great distances. That, and of course,
gravitational lensing.There are different astronomical instruments that can be used
in the system itself, I saw the press release that AMBER was completing test trials.
On the question about red shift 2 equaling "c", I am not sure nowadays. A few years
ago, galaxies began showing up older than the universe itself, something like 17 billion
years old. The classic Special Relativity formula for figuring red shifts had to be modified. The scales used today are not linear, in other words a red shift of z=3
is almost 11 1/2 billion light years, but z=10 is about 13.2 billion light years. I think somewhere below z=3, the velocity of "c" is exceeded, but I am not positive.
Also, I suppose you know this, but I was somewhat confused by your above post,
that we cannot see the light of the BEGINNING of the Big Bang. The first thing we
can detect is the microwave radiation from the cosmic background (CMB) which was
about 379,000 years after the Big Bang. The first visable light was not produced for
another 3-4 million years, during the first star formation and then galaxies after that.
When I say visable light, remember that light has by now been red shifted into the
near-infrared region, so more equipment is needed for detection. The VLT array is
composed of optical telescopes with various instruments.

[Erring Flatley]

Hello Physics 101, Crabhaver, Do you still reject the idea of a steady state universe? I still think I am right. I am having trouble imaging in my mind how it is possible for us to see the cosmic microwave backround radiation (CMBR) in all directions, at this time. It seems to me it ought to be seen in only one direction. The direction of the original center of the big bang. Your opinion?

[crabhaver]

Hi erring!

Good to see you here. About your theory, I am up for anything. Your theory makes the most sense on the surface, and using ye old achim's razor it is the simplest. However, I don't want to stop without fully researching other avenues also. I have realized with all the worldly common sense I have gained, it is by no means universal. Pardon the pun, but my street smarts have rarely applied in reasoning many facets of physics. I am approaching the acceptance phase to many concepts, however, I still have a long journey to understanding. Why don't you mention your theory here. There are some amazingly intelligent and knowledgeable people utilizing Sciforums, and I have seen no unprovoked egotism here.

2Inq. Wasn't sure on the VLT. I know it was supposed to go active (interferometry) 2004 or 2005. If it hasn't I couldn't imagine the power of that SOB once it happens.

About that other explanation by the MIT guy, as soon as you use fractions or equations I need pictures. Maybe someone else can elaborate more.