archived as http://www.stealthskater.com/Documents/BigBang_07.doc [pdf]
more of this topic at http://www.stealthskater.com/Science.htm#Ekpyrotic
note: because important websites are frequently "here today but gone tomorrow", the following was
archived
from
http://www.newscientist.com/article/mg20126921.900-dark-flow-proof-ofanother-universe.html on January 23, 2009. This is NOT an attempt to divert readers from the
aforementioned website. Indeed, the reader should only read this back-up copy if the updated
original cannot be found at the original author's site.
Dark Flow: proof of another universe?
by Amanda Gefter
New Scientist / January 22, 2009
For most of us, the Universe is unimaginably vast. But not for cosmologists. They feel decidedly
hemmed in. No matter how big they build their telescopes, they can only see so far before hitting a wall.
Approximately 45 billion light years away lies the "cosmic horizon" -- the ultimate barrier because light
beyond it not has not had time to reach us.
So here we are, stuck inside our patch of Universe, wondering what lies beyond, and resigned to that
fact we may never know. The best we can hope for through some combination of luck and vigilance is
to spot a crack in the structure of things -- a possible window to that hidden place beyond the edge of the
Universe. Now Sasha Kashlinsky believes that he has stumbled upon such a window.
Kashlinsky (a senior staff scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland)
has been studying how rebellious clusters of galaxies move against the backdrop of expanding space.
He and colleagues have clocked galaxy clusters racing at up to 1,000 kilometer- per-second -- far faster
than our best understanding of Cosmology allows. Stranger still, every cluster seems to be rushing
toward a small patch of sky between the constellations of Centaurus and Vela.
Kashlinsky and his team claim that their observation represents the first clues to what lies beyond the
cosmic horizon. Finding out could tell us how the Universe looked immediately after the 'Big Bang' or
if our Universe is one of many.
Others aren't so sure. One rival interpretation is that it is nothing to do with alien universes but the
result of a flaw in one of the cornerstones of Cosmology -- the idea that the Universe should look the
same in all directions. That is, if the observations withstand close scrutiny.
All the same colleagues are sitting up and taking notice. "This discovery adds to our pile of puzzles
about Cosmology," says Laura Mersini-Houghton of the University of North Carolina, Chapel Hill.
Heaped in that pile is 95 percent of the Universe's contents including the invisible "dark matter" that
appears to hold the galaxies together and the mysterious "dark energy" that is accelerating the
Universe's expansion. Accordingly, Kashlinsky named this new puzzle the "dark flow".
Kashlinsky measures how fast galaxy clusters up to 5 billion light-years away are travelling by
looking for signs of their motion in the cosmic microwave background (i.e., the heat left over from the
'Big Bang'). Photons in the CMB generally stream uninterrupted through billions of light-years of
interstellar space. But when they pass through a galaxy cluster, they encounter hot ionized gas in the
spaces between the galaxies. Photons scattered by this gas show up as a tiny distortion in the
1
temperature of the CMB. And if the cluster happens to be moving, the distortion will also register a
Doppler shift.
This high-resolution map of microwave light emitted only
380,000 years after the 'Big Bang' defines our Universe more
precisely than ever before. The eagerly-awaited results from
the orbiting Wilkinson Microwave Anisotropy Probe resolve
several long-standing disagreements in Cosmology. (Image:
WMAP Science Team / NASA)
In any individual cluster, this shift is far too small to detect. Which is why no one had ever bothered
looking for it. However, Kashlinsky realized if he combined measurements from a large enough number
of clusters, the signal would be amplified to a measurable level.
Kashlinsky and his team collected a catalogue of close to 800 clusters using telescopes that captured
the X-rays emitted by the ionized gas within them. They then looked at the CMB at those locations
using images snapped by NASA's WMAP satellite. What they found shocked them.
Galaxy clusters are expected to wander randomly through their particular region of space because
matter is distributed in uneven clumps, creating local gravitational fields that tug on them. Over large
scales, however, matter is assumed to be spread evenly. So on these scales, the clusters should coast
along with space as it expands. What's more, everything in the standard model of Cosmology suggests
that the Universe should look pretty much the same in all directions.
Out of Bounds
So what is behind the "dark flow"? It can't be caused by dark matter, Kashlinsky says, because all
the dark matter in the Universe wouldn't produce enough gravity. It can't be dark energy, either, because
dark energy is spread evenly throughout space. That, leaves only one possible explanation, he
concludes. Something lurking beyond the cosmic horizon is to blame.
Before the findings were published in October in The Astrophysical Journal Letters (vol 686, p
L49), Kashlinsky knew how heretical his idea would seem. "We sat on this for over a year checking
everything," he says. "It's not what we expected or even wanted to find, so we were skeptical for a long
time. But ultimately it's what's in the data."
No one knows exactly what might lurk over the horizon or indeed how large the Cosmos is (see
"Just how big is the Universe?"). But Kashlinsky suspects it is a remnant of the chaotic state that existed
just a fraction-of-a-second after the beginning of Time before a phenomenon known as "Inflation" took
hold.
It is generally thought that our Universe began as a tiny patch in some pre-existing space-time
forming a bubble which then underwent a burst of exponential expansion. This period of Inflation
stretched and smoothed our Universe, leaving an even distribution of matter and energy.
But outside this bubble -- far beyond our cosmic horizon -- things might look very different.
Without Inflation's ironing skills, space-time could be highly irregular: smooth in one neighborhood and
with massive structures or giant black holes in another.
2
"It could be as bizarre as one can imagine or something rather dull," says Kashlinsky. Either way, he
suggests that something outside our bubble is tugging on our galaxy clusters, causing the "dark
flow".
Other, more radical explanations for dark flow have also been floated. It is possible (even likely,
some say) that ours wasn't the only bubble to inflate out of primordial space-time. In this "Eternal
Inflation" scenario, bubbles pop up all over the place, each defining its own universe within a larger
Multiverse.
Many cosmologists are happy to relegate those other universes to that dusty corner of theory where
unobservable by-products are stored. But Mersini-Houghton is not one of them. She argues that the
"dark flow" is caused by other universes exerting a gravitational pull on galaxy clusters in our Universe.
She and her colleagues calculated how other universes -- scattered at random around our bubble -would alter the gravity within it (www.arxiv.org/abs/0810.5388).
"When we estimated how much force is exerted on the clusters in our Universe, I was surprised that
the number matched amazingly well with what Kashlinsky has observed," she says. "I firmly believe
that this is the effect of something outside of our Universe."
Others believe "dark flow" could be a sign that our bubble universe crashed into another bubble just
after the 'Big Bang'. In Eternal Inflation, each bubble universe can pop into existence with its own
unique set of particles and forces of nature. So collisions between bubbles can have dramatic
consequences.
If 2 universes with the same physics collide, they will generate a burst of energy and then merge.
However, if 2 very different universes collide, a cosmic battle ensues. At the site of the crash, a wall of
energy called a "domain wall" will form, holding the 2 incompatible worlds apart. The bubble with
lower energy then expands, sending the domain wall sweeping through its rival and obliterating
everything in its path.
If our Universe underwent such a collision, any lingering evidence of the cosmic wreckage should
appear in the part of the sky facing the impact site. The collision's impact should distort space, and that
would in turn affect how light rays (including the CMB) travel through it and how large-scale structures
(including galaxies and clusters) evolve. Looking out across the sky today, we would expect to see the
Universe exhibiting strange properties in the direction of the collision.
The collision might have imprinted a special direction onto the CMB, says physicist Anthony
Aguirre of the University of California, Santa Cruz. "As you move away from the special direction, the
temperature of the CMB would change."
Physicists are now combing the data looking for the hallmarks of such a shift. Whenever there are
weird things happening on a large scale within the galaxy, the remnants of a collision are a candidate for
explaining it, Aguirre says.
A completely different take on "dark flow" comes from Luciano Pietronero of La Sapienza
University in Rome, Italy and Francesco Sylos Labini of the Enrico Fermi Center in Rome, Italy. They
say the standard cosmological model is wrong and that a different model might explain the motion of
galaxy clusters that Kashlinsky found.
"This is just another element pointing toward the fact that the standard picture of galaxy formation is
not correctly describing what is going on in the real universe," Pietronero says.
3
Predictions of the motion of galaxy clusters based on the conventional model assume that matter is
evenly distributed throughout space on very large scales. Pietronero and Sylos Labini claim analysis of
the distributions of galaxies and galaxy clusters throughout the sky shows that this is not true and that at
large scales matter is like a fractal.
If that is the case, the gravitational field throughout the Universe would also be irregular and could
lead to the effects Kashlinsky observed. New results from the Sloan Digital Sky Survey -- which has
already mapped about a million galaxies -- will help give Pietronero and Sylos Labini a more precise
picture of the spread of matter which they hope will confirm their ideas. " I think we will have
interesting news very soon," says Sylos Labini.
A fractal universe would, however, raise big problems of its own. For one thing, a fractal
distribution of matter is incompatible with Cosmic Inflation. So theorists would be left to figure out
how it arose in the first place (New Scientist, March 10, 2007, p 30).
Physicist Douglas Scott of the University of British Columbia in Vancouver, Canada is also
skeptical that "dark flow" is evidence of anything outside our observable universe. " There is no reason
at all to expect it to come from structures beyond the horizon," he says.
Scott notes that so far, "dark flow" has only been observed out to distances that are only a few
percent of the total distance to the horizon. "If the effect is real," he says, "then the likely explanation
would be some very large-scale structure but still within the horizon." Such a structure, though, would
still present a major challenge to Cosmology's standard model.
The most important thing now is to confirm that "dark flow" is real and that it continues all the way
out to the cosmic horizon. 2 other teams have made measurements consistent with Kashlinsky's results.
But only on scales less than 200 million light-years -- just a short step compared to the distance out to
the horizon.
To confirm their finding, Kashlinsky's team will be analyzing more recent WMAP data and working
with researchers at the University of Hawaii on data from an all-sky X-ray catalog. The tiny Doppler
effect that Kashlinsky uses to measure the clusters' velocities is only observable in bulk. Which means
the more galaxy clusters he can look at, the better.
"If confirmed, this will be an exciting way of probing the ultimate structure of the universe and
perhaps even the Multiverse," Kashlinsky says. "But you have to check and recheck."
"If this thing is confirmed and it is real, it will be incredibly important," says Aguirre. "On the same
order of discovery as the realization that those little smudges on the sky are other galaxies. The most
important thing it would tell us is that the standard picture is broken in some way. And the most
exciting thing it could tell us is that there are other universes."
If it does, space and time will open up to reveal a reality that is so much bigger than we know.
When that happens, those claustrophobia-stricken cosmologists will finally be able to breathe easy.
Just how big is the Universe?
It is 13.7 billion years since the 'Big Bang'. So light now reaching us cannot have started its journey
longer ago than that. Yet the most distant object we could conceivably see today lies further away than
13.7 billion light-years. That's because throughout the life of the Universe, space has been expanding.
4
Taking this into account, cosmologists calculate that the edge of our observable Universe is now
approximately 45 billion light-years away.
Beyond that, who knows? The Inflation theory of Cosmology predicts that the Universe grew from
a bubble. Just how big that bubble has now become depends on how long Inflation lasted. If it
continued for a very long time -- in this context, "very long" is still only a fraction-of-a-second -- then
the edge of our Universe might lie far beyond the 45-billion-light-year limit of our vision.
That could also rule out the possibility of observing the influence of other universes on our own. As
physicist Matthew Kleban of New York University puts it: "It's totally possible that we live in a
Multiverse and we'll never know because there's been so much inflation."
Readers' Comments
1. It Depends On Your Perspective
by John Scanlan / Thu Jan 22, 2009 15:22:32 GMT
The Universe only appears to be expanding. It can be actually collapsing. We may be rushing
back to the point of origin.
And both can be happening at the same time. Which applies to you depends on your perspective.
2. by Slobodan / Thu Jan 22, 2009 20:25:24 GMT
Good point. With described anomaly, it is not out of mind to get such a clue.
5
This is very interesting article. It reminds me again on Steinhardt-Turok "Brain Universe"
theory (http://wwwphy.princeton.edu/~steinh/).
The Steinhardt-Turok model is based on the idea that hot 'Big Bang' Universe was created from
the collision of two 3-dimensional worlds moving along a hidden, extra dimension. The two 3dimensional worlds collide and "stick". The kinetic energy in the collision is converted the quarks,
electrons, photons, etc. that are confined to move along 3 dimensions. [StealthSkater note:
possibly referring to the Ekpyrotic model which is based on string/M-brane theory => doc pdf
URL ]
The resulting temperature is finite, so the hot 'Big Bangi phase begins without a singularity. The
Universe is homogeneous because the collision and initiation of the 'Big Bang' phase occurs nearly
simultaneously everywhere.
Professor Steinhardt predicted that whenever the 4th spatial dimension fluctuate to its minimum,
the extra dimensional distance between two "branes" cause ripples in our 4-D Universe due to the
different gravitational pulls between branes.
Such ripples could "drag" space-time in our Universe (more on certain hot spots), causing strong
gravitational pull which should drag galaxy clusters in one particular direction just as S. Kashlinsky
described in his research.
It is another anomaly in the light of the classical 'Big Bang' theory and another evidence that
some other models should be considered and evaluated more thoroughly.
3. by Polemos / Fri Jan 23, 2009 12:31:13 GMT
"Collapsing" is a misnomer here.
Collapse implies that the periphery is getting closer to the center (i.e., the center stays put).
Implosion implies that the periphery stays put while the center is becoming smaller.
Observations show that the periphery is receding. Therefore the Universe is imploding -- not
collapsing.
4. by Dan / Fri Jan 23, 2009 14:36:18 GMT
This is one good hypothesis that is testable. If the observable Universe is imploding, unless the
Earth is at the exact center of the implosion, the peripheral stars in one hemisphere should recede
faster and the other more slowly.
I see 3 other possibilities. (1) The historical effect of something now outside the observable
Universe because of Inflation. (2) The current effect of a huge clump of dark matter inside the
visible Universe. Or (3) a huge mass of ordinary matter hiding in the region just within the
observable Universe but outside the visible Universe.
In the last case, the motion of visible objects could be affected by the gravity of the hidden mass
even though any light it produced would have been blocked by the curtain of unionized particles that
shrouded the origin of Time from sight.
6
5. by Polemos / Fri Jan 23, 2009 15:04:01 GMT
Dan, even if the observer is located halfway between the imploding Universe's center and its
periphery, it will seem to him that both the center and the periphery of the Universe are receding
from him.
Moreover, even objects positioned at the same distance from the Universe's center will be
apparently receding from each other (because the Universe is gravitationally imploding both globally
and locally, and the acceleration of the local implosion is higher than the acceleration of the global
implosion).
6. Towards The Centre Of The Gravitational Toroid
by Polemos / Fri Jan 23, 2009 12:25:21 GMT
The Universe is a black hole.
Black
swf.de/publikationen/pascal.pdf ).
holes
are
cardioidal
(http://haegar.fh-
This means that the Universe is a toroidal current of Time (=universal gravity, dark energy)
flowing within the spheroid of Space and turning the latter into a cardioid.
The "dark flow" is heading towards the narrow-most point of the toroidal gravity current
7. by George / Fri Jan 23, 2009 13:20:04 GMT
Polemos, I've read this and the linked paper. This is meaningless.
With respect -- and given your repeated postings of similar material in various topics - WHAT
are you on about? Please restate in either English or mathematics.
8. by Polemos / Fri Jan 23, 2009 14:07:30 GMT
If you do not understand something, it may also mean a lack of general knowledge on your part.
Just ask politely what exactly is incomprehensible.
Gravitational contraction + angular momentum conservation = toroidal current. See this paper:
"On the Evolution and Gravitational Collapse of a Toroidal Vortex" (http://arxiv.org/abs/astroph/0407320 ).
9. by George / Fri Jan 23, 2009 14:55:03 GMT
Polemos, my general knowledge is pretty OK ;)
One point is that angular momentum is only definable from an external frame. If the whole
Universe is spinning, what is it spinning in relation to? There doesn't seem to be any detectable
favored direction/axis in the Universe as we understand it.
All the papers that you refer to seem to be making valid points that are irrelevant to your
arguments. With respect, I'm not alone in my incomprehension. You even managed to make an
appearance in the end-of-year print edition for similar reasons.
10. by Julian / Fri Jan 23, 2009 14:58:44 GMT
7
In the referenced paper which describes "black Hole Shadows" (not black holes per sunt), it says
"for B = A, it [the curve of Pascal's limacon] is a cardioid".
In the table in Section 5 where approximations are given for Black Hole parameters, B is greater
than A throughout. Which is not the cardioid case. Even if it were, the author says just above this
that "a closer analysis shows that the shadows are not exact limacons" so there is precisely zero
support for the assertion that "Black Holes are cardioidal". And even if what "this means" means
anything at all (what is a "current of time"???), it cannot possibly be a consequence of cardioidality
of Black Holes.
Really, Polemos, give us a break! If you're going to dribble all over the comments pages, please
try not to spit out your last half-digested meal with it.
11. Going At The Speed Of Gravity
by Pelotard / Fri Jan 23, 2009 13:11:42 GMT
If light hasn't had the time to travel that far, how can Gravity have travelled that far? Last I
heard, it was suspected to be mediated by massless gravitons and not instantaneously appear on the
other side of the Multiverse.
12. by Polemos / Fri Jan 23, 2009 14:29:27 GMT
Gravitons are quanta of gravitational field (also called "gravitational radiation"). Gravitational
radiation propagates at the speed-of-light. The gravitational potential (the "Coulomb component" of
a gravitational field( propagates instantly.
http://en.wikipedia.org/wiki/Speed_of_gravity#Background :
"General Relativity predicts that gravitational radiation should exist and propagate as a wave at
the speed-of-light. To avoid confusion, we should point out that a slowly evolving source for a weak
gravitational field will produce -- according to General Relativity -- similar effects to those we might
expect from Newtonian gravitation. In particular, a slowly evolving Coulomb component of a
gravitational field should not be confused with a possible additional radiation component (see Petrov
classification).
"Nonetheless, any of the Petrov-type gravitational field obeys the Principle of Causality so that
the slowly evolving 'Coulomb component' of the gravitational field cannot transfer information
about position of the source of the gravitational field faster than the speed-of-light."
13. Observing Beyond The Observable Universe
by Nick Hamilton / Fri Jan 23, 2009 13:15:31 GMT
Much is made of the idea that 'dark flow' may be a "window to that hidden place beyond the
edge of the Universe". If so, then we are observing effects from beyond the edge of the observable
Universe. Thus whatever is creating those effects is observable. Or is this perhaps an observable
effect of grant-writing season?
14. A Bit Premature?
by Mark_S / Fri Jan 23, 2009 13:41:46 GMT
8
I find this fascinating from the point-of-view of the psychology of science. Broadly speaking,
researchers working in fields as diverse as Earth sciences, Biology, Chemistry, and most fields of
Physics tend to be quite careful to report their results in a limited, focused manner along the lines of
(1) accepted theory & existing data; (2) new data and/or model; (3) revised interpretation &
implications. It is a highly conservative, almost clichéd format that may be boring … but works.
Oddly though, certain disciplinary subsets within high-energy particle physics and astrophysics
seem to attract a greatly disproportionate number of theorists ready to charge madly off in wholly
speculative directions long before enough hard data is collected to make a sensible appraisal (dark
matter! no, dark energy!! no, multiple universes!!! NO, multiple universes with 11-dimensional
space-time -- none of them observable by mortals!!!!).
Sometimes I wonder if the reason for this may be as mundane as drumming up funding for
expensive telescopes and particle accelerators. And the salaries of those who use them.
The long-term effect of these wild, premature and often stillborn claims -- at least from my point
of view -- is to bring the fields involved into disrepute.
15. Is Our Unibubble A Cube?
by Boozer / Fri Jan 23 15:25:02 GMT 2009
A single soap bubble floating on the breeze is fairly spherical. But foam bubbles are all kinds of
shapes, aren't they?
For instance, stuffing many balloons in a box will produce cube balloons. If we can detect a
gravitational hotspot on one side of our uni-bubble, then maybe a similar hotspot can be found in the
opposite direction and above and below. Assuming that uni-bubbles are of similar size, in theory a
hotspot should be surrounded by 4 cold-spots.
16. Dark Flow: Proof Of Another Universe?
by Klar Stempien / Fri Jan 23, 2009 16:21:18 GMT
Dark flow? Groping for answers, are they? Now we're to ponder neighboring universes as
patches to help explain the bewilderment in ours!
This is all conjecture as are all their theories. Yet, I must admit, serves as a wealth of fodder for
science-fiction movies. The mathematics make as much sense as minus time. Yet, the answer is in
the article "ionized gas". All one need do is realize that ionized gas is a plasma and is everywhere
in the Cosmos (its far reaching effects only dominate gravity by 1036 to 1039 times) and behaves
quite differently than -- and independently of -- gravity.
Perhaps you could assist in the re-education of the current realm of comatose "scientists".
This site highlights a theory that predicts events without resorting to any patches whatsoever, -i.e., it works: (summary's a good place to start)
http://www.electric-cosmos.org/indexOLD.htm.
17. Dark Energy
by Stephen Tash / Fri Jan 23, 2009 16:22:12 GMT
9
Once again, "dark energy" is given this mysterious quality (though it is not the main topic of the
article). Dark energy is simply explained by equal amounts of matter and antimatter which affect the
fabric of spacetime in equal-but -opposite manner. One could simply say that matter creates gravity
and anti-matter creates anti-gravity.
A small bit of anti-matter creating an anti-gravity well amidst a large gravity well dominated by
matter will slide down (or perhaps up if you want to see it more visually) the gravity well to create
the least resistance to its opposite manipulation of space-time. The reverse (but conceptually the
same) would be true of a small gravity well created by a particle of matter in a larger anti-gravity
well of anti-matter. Visually, it would slide down the anti-gravity well.
Now if you have a gravity well created from a matter-based galaxy or galaxy cluster and an antigravity well created from an antimatter-based galaxy or galaxy cluster, they are going to repel to
reduce stress on space-time.
This principle was evidenced by the recent experiment (long URL - <click> here) where antimatter was proven to deflect off of matter, not simply annihilate. It theoretically should take a very
powerful and precise collision to cause the anti-gravity well and gravity well to overlap one another
and annihilate.
The repulsive force of alternating blotches of matter and anti-matter (perhaps a fairly minimal
statistical anomaly of the original distribution of matter and anti-matter in the 'Big Bang', perhaps the
resulting energy from annihilation fueled inflation?) would create a positive repulsive force between
those blotches. Because there would be more and more repulsion happening constantly, the force of
the resulting energy should accelerate.
So far, this matches observations of dark energy. Perhaps the easiest test (beyond the bouncing
results earlier recorded) is that dark energy should accelerate less-and-less over time because the
continuous pushing between the gravity wells and anti-gravity wells should grow weaker as distance
increases.
Ultimately, this is just the application of Occam's Razor. If every action has an equal and
opposite reaction, equal amounts of matter and anti-matter that would follow this law. And equal
and opposite effects on space-time -- which would also follow this law -- would be expected.
18. Speculation
by Greg / Fri Jan 23, 2009 16:52:10 GMT
While these attempts to explain "dark flow" are all good, it is still too early to say with any
certainty what is causing this. I do think it is time for proponents of various theories to lay their
predictions on the line as to what the data will show in order to gain or lose credibility.
First, this finding must be confirmed by further scrutiny of WMAP data as it comes in and by
tracing the signal to the visible horizon. Most likely the data will hold this discovery up as this work
appears to be solid. We will be able to tell the location and mass of the anomaly responsible for dark
flow in the same way we can determine the location and mass of a supermassive black hole in a
galaxy by observing the motion of the stars revolving around it. I think what we will find is a
massive relic leftover from the Inflation period. In any event, the standard 'Big Bang' model will be
in need of revision.
10
Also this finding would reveal fundamental truths regarding the structure of our Universe. Very
exciting news indeed if it holds up.
As for Polemos, you needs to simplify into plain English whatever abstractions you are referring
to so that people outside a very narrow circle can consider what you are proposing. Not doing so is a
misuse of a public forum. As a result, you are coming off as an elitist at best and really quite mad at
worst.
(For the record, I did pursue your references supporting one of your posts and found your logic
incoherent and unsubstantiated. In that particular case, you were posting suppositions about
quantum gravity as if they were known fact when in actuality this area of Cosmology is highly
speculative and theoretical.)
19. Speed of Light And Gravity
Fri Jan 23 17:24:19 GMT 2009 by ian
IF gravity also travels at lightspeed, then we should not be able to see the effects of anything
beyond the light horizon any more than we can see beyond it ourselves. If there is an observable
effect, then some fundamental physics needs re-thinking.
if on the Internet, Press <BACK> on your browser to return to
the previous page (or go to www.stealthskater.com)
else if accessing these files from the CD in a MS-Word session, simply <CLOSE> this
file's window-session; the previous window-session should still remain 'active'
11