A Cyclic Universe and Pussycats
Last week our good friend Margaret from California visited us.
When asked what she wanted to see during her stay her answer
was, "Of course Ground Zero." Most people I know in our area
of New Jersey have neither seen, nor wanted to see Ground Zero
because of its painful associations. However, I drove in to New
York and Margaret and I took our turn on the viewing platform.
Although I''d been in the World Trade Center a couple of times, I
found it hard to imagine that those imposing Twin Towers had
stood in the empty space in front of us. We could not see into
the bottom of the pit but the damage to the surrounding buildings
was quite apparent. The dimensions of the tragedy were hard to
comprehend. There were, however, an overwhelming number of
messages, pictures, mementos, banners and fresh flowers lining
the walls along the entrance and exit from the viewing platform.
These helped bring the dimensions of 9/11 down to a human
scale that one could comprehend and reflect upon.
After visiting Ground Zero, I came home determined to follow
through on my promise last week to deal with deeper subjects
than making foul shots or highway pavement. I specifically had
promised to consider the new theory of the creation and future of
the universe that made such a big splash in the media a month or
so ago. But first, let''s set the stage. Back in March of this year, I
wrote about Guth''s theory of "inflation", which postulates that
the universe expanded furiously in a tiny fraction of the first
second after the Big Bang. In this teensy fraction of a second the
universe inflated from a ridiculously tiny speck to the size of a
marble, a remarkable increase in size over such a short time.
Data from the Hubble telescope and various other sources
strongly supported this theory. The initial speck was thought to
have resulted from a random quantum fluctuation out of nothing,
as I described in the March 14 column (see archives). I felt that,
even though I couldn''t comprehend the theory, I could accept it
in the belief that vastly superior intellects understood such
The inflation model explained a couple of major problems. One
was the formation of ripples in the composition of the universe
that led to the formation of stars and galaxies. Also explained
was the fact that our universe is "flat" and not "closed". (One
characteristic of a flat universe is that two rays of light that start
out parallel to each other will stay parallel. In a closed universe
these rays of light will converge and I gather we might actually
be able to see ourselves if we lived long enough for the light rays
to curve back to us.) Another profound implication of the Big
Bang/inflation model is that time itself began at the moment of
the Bang. Everything seemed to be falling into place.
After that rapid inflation, the universe expanded at the more
reasonable, though still mind-boggling, rate that we have today.
At least that''s what was thought to be the case. However, a few
years ago, there was the disturbing finding that our universe was
actually expanding at an accelerating rate. This newly found
second period of "inflation" was not anticipated in the inflation
model. Soon you began hearing about "dark energy", the
unknown force that was speeding up our expanding universe.
Now, just a month or so ago, comes a theory that could topple
the inflation scenario and that gives a much different picture of
our past and future. Needless to say, I was all shook up, having
convinced myself that I could rest easy in my belief that someone
had truly understood our ultimate origins. So it was with much
trepidation that I picked up my May 24 2002 issue of Science,
determined to actually read the articles in the special section with
the daunting title "Spacetime, Wrapped Branes and Hidden
Dimensions". After reading the three introductory review
articles in this special section, my brane-addled brain was
reeling. However, I decided to plow ahead to the article by Paul
Steinhardt of Princeton and Neil Turok of Cambridge that caused
all the media stir.
However, when I turned the page to go on, there was a one-page
article that I suspect the editor of Science put there to provide
some comic relief from the difficult material surrounding it. The
article, by Denis Burnham and co-workers from Australia, was
titled "What''s New, Pussycat? On Talking to Babies and
Animals"! Aha, I thought - this is a subject I can understand.
However, this paper wasn''t as simple as I anticipated. There
were terms such as "affect" and its characterization by
measurement of ''low-pass-filtered speech"; hyperarticulation of
the "corner" vowels with associated plots in F1-F2 space.
I was out of my league, but having brought up the subject, I
should tell you what the article concluded. First, mothers talk
differently to babies than to adults. But you already knew that,
didn''t you? The authors studied 12 mothers talking to babies,
pet dogs or cats and to adults. They found certain distinct
patterns. When the mothers talked to their babies or pets, they
raised their pitch and affect (intonation and rhythm) compared to
when they talked to an adult. However, they did not exaggerate
their vowels for either their pets or an adult. This was taken to
mean that one intuitively perceives the emotional and linguistic
needs of one''s audience. The baby, but not the pet or adult, is
presumed to need the exaggerated vowel delivery to assist it in
its own language development.
I was hoping the "pussycat" article might provide sufficient
material to fill this column but no such luck. So it''s on to the
paper by Steinhardt and Turok entitled "A Cyclic Model of the
Universe". Surprisingly, this monumental paper was not even
four pages long, with just one figure and 7 equations. I
understood none of the equations. However, I''ll take a stab at
conveying some of the essence of the cyclic model.
In this cyclic model, there is still a Big Bang. Thank goodness
for that! Let''s put off for the moment how the Big Bang started.
Instead, let''s begin with where we are now, some 14 billion years
or so since the Big Bang, in a universe that is expanding at a
faster and faster rate. Steinhardt and Turok expect that this
expansion will go on for trillions and trillions of years, past the
time when our night sky will be completely black, all the other
stars and galaxies so far away that we can no longer see them.
But that''s only the beginning. The universe keeps on expanding
until it is essentially as empty as "nothing" - so empty that there''s
only one particle in a "Hubble volume". (From what I can gather
on the Web a "Hubble volume" is the size of our visible universe.
That''s pretty big to contain just one particle!) At about this
point, expansion stops and contraction begins.
Now, the nature of this contraction eludes me, to be perfectly
frank. While there is mention of a "crunch", it''s apparently
different from the old notion that all the stars and galaxies come
back together in a big crunch that starts things off again. Instead,
the theorists think that our universe lies in a 4-dimensional
"brane". "Brane" is short for membrane and the analogy is akin
to a thick 3-dimensional rubber sheet or membrane. This brane,
however, is in 4 dimensions, which makes it hard to visualize for
any normal human being. Obviously, the brane has to be huge to
contain our universe. But that''s not all. There seems to be an
important 5th dimension that connects our own brane with
another brane. Our brane contains all the normal kinds of stuff
we know and love. The other brane contains weird stuff
connected with gravity and dark matter. Sometime during the
contraction phase, the 5th dimension collapses for a moment and
the two branes bump into each other and "bounce" off. Voila!
This bump-bounce initiates another Big Bang and our universe is
again off and running.
I don''t pretend to understand all this but let''s look at some of the
conclusions if the cyclic model of the universe is correct. One
concerns the beginning of time. Time began with the Big Bang
under the inflation model. The cyclic model says that, since the
process of expansion and contraction is a continuous process,
there is no beginning or end of time. Time just is. Heady stuff
indeed! In the cyclic model, the newly discovered dark energy
that''s pushing our universe apart arises naturally out of the
model. Also, there are not two periods of inflation, just the one
that we''re in now. The Big Bang does not originate from random
quantum fluctuations in the cyclic model. Instead, it arises from
the colliding branes and no weird quantum gravity effects are
needed. Some of you might be saying, "Hey, those branes are
pretty weird themselves!" I certainly agree.
So, we have these two conflicting pictures of how the Big Bang
came to pass and of what our universe''s future will be. Which is
correct? It seemed as though the inflation model was a lock until
this theory arose. Steinhardt and Turok say that there will be
ways to decide definitively between the two alternatives through
measurements of gravitational waves and the properties of dark
energy. The two theories predict different wavelengths and such.
Since it will take the utmost in instrumental and scientific
expertise to even make these measurements, we may have to wait
for many years for the answer.
Allen F. Bortrum