Dear Professor Carroll,

Your recent paper about the apparent acceleration of the universe [Ref. 1] is the best I've ever read. Thank you!

Regarding the "scandal" due to the coincidence problem, and Sec. 1.3.3, Is dark energy dynamical?, please see

http://members.aon.at/chakalov/Sormani.html

http://members.aon.at/chakalov/Professor_X.html#Negative_Mass

I will highly appreciate your comments, as well as those from your colleagues. I will keep them private and confidential.

Regards,

Dimi Chakalov
http://members.aon.at/chakalov
http://members.aon.at/chakalov/white_paper.html

--

[Ref. 1] Sean Carroll, Why is the Universe Accelerating? Mon, 13 Oct 2003 22:55:24 GMT, astro-ph/0310342

"In trying to understand the universe in which we apparently live, we are faced with a problem, a puzzle, and a scandal.
...

"Dark energy" is not, strictly speaking, the most descriptive name for this substance; lots of things are dark, and everything has energy. The feature which distinguishes dark energy from ordinary matter is not the energy but the pressure, so "dark pressure" would be a better term. However, it is not the existence of the pressure, but the fact that it is negative -- tension rather than ordinary pressure -- that drives the acceleration of the universe, so "dark tension" would be better yet. And we would have detected it long ago if it had collected into potential wells rather than being smoothly distributed, so "smooth tension" would be the best term of all, not to mention sexier.
...

"The acceleration of the universe presents us with mysteries and opportunities. The fact that this behavior is so puzzling is a sign that there is something fundamental we don’t understand. We don’t even know whether our misunderstanding originates with gravity as described by general relativity, with some source of dynamical or constant dark energy, or with the structure of the universe on ultralarge scales. Regardless of what the answer is, we seem poised to discover something profound about how the universe works."
 
 

Note: It seems to me that the "dark" component of the universe is both constant and dynamical, and we could model the universe as a huge brain that "thinks" with its virtual or "dark" state. But before going into such speculations, let's examine the bold data.

Look at the black dots in Fig. 4 from Saul Perlmutter's Supernovae, Dark Energy, and the Accelerating Universe (Physics Today, April 2003, p. 57),
 

You can download the image (expansionhistoryphystoday.pdf) by clicking on the thumbnail above, and the article by Saul Perlmutter here. He wrote (p. 57): "Given these two fine-tuning coincidences, it seems likely that the standard model is missing some fundamental physics. Perhaps we need some new kind of accelerating energy -- a "dark energy" that, unlike [lambda], is not constant."

The observations (black dots in Fig. 4 above) permit one conclusion only: the history and the fate of the universe are undecidable. See also Paul Frampton and Tomo Takahashi, The Fate of Dark Energy, astro-ph/0211544 v4: "Our dreadful conclusion is that no amount of data from our past light-cone can select between these future scenarios."

The assumption of flat cosmic geometry in Saul Perlmutter's article (see also Ryan Scranton et al., Physical Evidence for Dark Energy, astro-ph/0307335 v2) is crucial for understanding the re-interpretation of the these observations: we shall drop this presumption and consider the most general case of dual topology, namely, closed-and-open in the global mode of spacetime, and asymptotically flat in the local mode of spacetime, as suggested here and here. Hence the universe has a dual age as well: finite in the local mode of spacetime, some 13.7 B years, and infinite (indecisive) in the global mode. The hypothesis for two modes of spacetime is explained here.

Now comes the hard question: what the heck is the source of this dark stuff? Let me quote from Paul Preuss' What is Dark Energy?:

"For the cosmological constant, the vacuum -- space itself -- possesses a certain springiness," says Eric Linder, a cosmologist at Berkeley Lab and director of the Center for Cosmology and Spacetime Physics at Florida Atlantic University. "As you stretch it, you don't lose energy, you store extra energy in it just like a rubber band."

The puzzle is that the more energy you poor into the universe for stretching the good old metric of spacetime, the more energy you get. From where?

How about Hermann Bondi's negative mass? The idea has been posted on this web site (Sunday, 3 November 2002) here. The source of this dark stuff could be the most widely known object in the past 2060 years: the atom of Lucretius. It is a special state of the whole universe as ONE. The positive and negative components of the universe are not exactly canceled, however. C’est la dissymétrie qui crée le phenomène, Pierre Curie (Journal de Physique 3 (1894) 393-415, p. 401). Hence we have a cosmological constant.

I think no new ideas are needed, just some real good math. Not Barbies.

One final quote, from astro-ph/0309368 by Robert A. Knop et al., p. 40: "As new instruments become available, it will begin to be possible to relax the condition of a constant equation of state parameter, and to question whether the properties of the dark energy have been changing throughout the history of the Universe."

Perhaps Mother Nature is smarter and has managed to employ all alternatives. Maybe the universe does evolve like a human brain (just don't ask why).

Let's be prepared for a delightful surprise. Only please don't tell me you knew nothing about it, okay?

Dimi Chakalov
Sunday, October 19, 2003

P.S. Steven Weinberg believes in the anthropic principle. No, this is not a joke. He presented a Public Lecture entitled "The Origin of the Universe" at the Cleveland Museum of Natural History at 7:30pm on Thursday, October 9th (see below).

David Gross described it as a disease: "Anthropic reasoning is a kind of virus. It infects people, and once infected they are lost forever."

I firmly agree. If the universe evolves as a human brain, there is no room for anthropic reasoning. Just biocosmology: the universe would anticipate its potential state some 13.7 billion years "after" The Beginning, and will proceed with fixing the initial boundary conditions suitable for life and consciousness. Why? Because it has two constituents, res extensa and res cogitans, in line with the basic ideas of Leibnitz and Pauli.

Besides, please note that 'the creation of the universe' -- a phrase which many cosmologists use without hesitation -- is a bona fide self-referential logical paradox. Let me explain.

The proposition 'the universe was created at some instant of time' is true if, and only if, it is false; and is false if, and only if, it is true. In order to identify the instant of Creation, t_c, we need a finite time interval, (t_c, t_n), where the index  n  refers to the instant 'now', some 13.7 billion years after t_c. However, here's the Catch 22: any finite time interval requires a cut-off that must be placed before t_c, therefore the initial proposition is false. To resolve this paradox, we place the cut-off,  t_0,  in the global mode of spacetime, where it can be safely canceled: (t_n - t_0) - (t_c - t_0) = t_n - t_c = 13.7 billion years, as read by your good old wristwatch, in your local reference frame (local mode of spacetime).

Mind you, the task of identifying the instant 'now' is a very old story, as told by St. Augustine of Hippo (354-430 AD). I've tried to elaborate on it here.

To cut the long story short, the very Act of Creation requires the Aristotelian First Cause endowed with self-acting faculties, just like the human brain: we think about the brain, with the brain. Hence The Universe (inside-the-universe plus its current Holon at time 'now', t_n) should be modeled as a brain.

As I am writing these lines, there is an ongoing Superstring Cosmology Conference at the Kavli Institute for Theoretical Physics at the University of California, Santa Barbara (Friday, October 24th, 9:00 AM PST, Main Seminar Room, limited to registered participants). This is what Jung and Pauli called synchronicity, isn't it? I sincerely wish all my colleagues from the Kavli Institute for Theoretical Physics best of luck in their endeavors.

There is no need to invent the wheel.

D.C.
Friday, October 24, 2003, 10:45:54 AM PST
 

Cosmology Meeting Explores the Outer Limits By Dan Falk Despite decades of living with Lou Gehrig's disease, Stephen Hawking continues to present papers at conferences such as the one in Cleveland last weekend. On the screen is an all-sky map of the cosmic microwave background from the WMAP satellite. Photo by Dan Falk.       October 15, 2003 | Seventy cosmologists gathered in Cleveland last weekend to discuss the latest observations and theories about the universe as a whole, and to speculate on what the next 25 years will bring. The first Kavali-CERCA Conference on the Future of Cosmology took place at Case Western Reserve University. It drew such luminaries as Steven Weinberg, Nobel laureate and author of The First Three Minutes, and Stephen Hawking of Cambridge University, author of A Brief History of Time. Speaker after speaker agreed that we're in a "golden age" of cosmological discovery, with many fundamental parameters of the universe — including its age, density, geometry, history, and overall composition — finally getting pinned down. Much of the best data in this regard came just this year from the spectacularly successful Wilkinson Microwave Anisotropy Probe, WMAP, which continues to map the cosmic microwave background radiation — the sky-filling "echo" of the Big Bang — better than has ever been done before. But many mysteries remain. What is the "dark energy" that's currently giving the expansion of the universe a boost of acceleration? What caused the Big Bang itself 13.7 billion years ago? Did it originate in a "singularity," an infinitesimal point at which the laws of physics break down? Or did it spring from some larger, underlying space-time and avoid a singularity? Are there many other bangs in this underlying realm, leading to many other, different universes? Does space have 10 dimensions instead of three, as string theorists suggest? If so, where are the other seven hiding? These and other questions will keep cosmologists busy for decades, speakers agreed. Dark energy was a hot topic. It amounts to about 73 percent of all the matter and energy in the cosmos, but its nature is completely unknown. However, astronomers are beginning to trace the history of its effects with some precision. Adam Riess presenting the latest findings on dark energy from his group's measurements of supernova distances and redshifts. Photo by Dan Falk.     Adam Riess (Space Telescope Science Institute) announced that his team has gotten a firmer fix on the time when the repulsive force of dark energy began overpowering the attractive force of gravity as galaxies spread apart from each other; this transition began the present era of cosmic acceleration. The change, he said, happened about 5 billion years ago — in line with previous, more tentative findings and nicely matching theoretical expectations. Riess's team is measuring the brightnesses of extremely distant Type 1a supernovae, "standard candles" that can be seen far across the universe, to track the history of cosmic redshifts. So is another team, led by Saul Perlmutter of the Lawrence Berkeley Laboratory in California. Topology. Cosmologists have long wondered about the geometry of the universe — whether space is flat or curved. The last few years have brought the answer: space is flat, and seemingly infinite. But what about its "topology," or connectedness? A finite volume of flat space could give the appearance of being infinite. A two-dimensional analogy might help: in a Pac-Man game, the video screen is small, but because the right-hand side is connected to the left (making the topology identical to that of a cylinder), Pac-Man can journey endlessly in one direction, even though the space he traverses is finite. Cosmologist Glenn Starkman (Case Western Reserve University) illustrated some of the ways space could fold back on itself. Photo by Dan Falk.     French cosmologist Jean-Pierre Luminet, US mathematician Jeffrey Weeks, and other colleagues published a paper in the October 9th Nature suggesting that we live in a relatively small universe with the topology of a hyper-dodecahedron -- a four-dimensional analog of the three-dimensional, 12-sided structure that roughly resembles a soccer ball. Their study was based on WMAP data suggesting a puzzling lack of very-large-scale patterns in the cosmic microwave background. However, by the time of the conference other researchers had taken a closer look and ruled out many scenarios for a connected universe, including the hyper-dodecahedron. (The possibility remains that connectedness exists on a scale larger than our 13.7-billion-light-year horizon, but we can never get any evidence about this.) Nobel laureate Steven Weinberg believes the anthropic principle offers the only good explanation for why the "cosmological constant" embedded in spacetime — one proposed basis for dark energy — is very small but not zero. Photo by Dan Falk.       Anthropics. One of the conference's more heated panel discussions focused on "anthropic reasoning," the idea that our own existence provides a basis for making scientific deductions that are reachable no other way. In its simplest form, the "anthropic principle" is uncontroversial. For instance, life requires air and water. So when scientists are born and notice their surroundings, they discover that they are on a world with air and water, rather than on a world like the Moon — even though Moonlike worlds are probably much more common in the universe. A key anthropic controversy centers on the fundamental constants of physics, such as the charge of the electron and the speed of light. Why do these have the particular values they do? There is no apparent reason for these values — they just "are." However, it turns out that any kind of life or organized matter — even such simple organized matter as atoms and molecules — requires many fundamental constants and laws to have special, seemingly "fine-tuned" values. Of course, we necessarily find ourselves living in just such a fine-tuned, life-friendly universe — otherwise we wouldn't exist to be thinking about it. Does this imply that there are many other universes having many other, random values for the constants, and in most of them life never happens? Does our universe appear special merely because we are engaging in self-selection from a much larger number of universes? Does this explain the special values we measure for such things as the atomic fine-structure constant? David Gross, on the other hand, considers the anthropic principle worse than useless. Photo by Dan Falk.     The debate centered on whether such logic constitutes a scientific "explanation." To some leading physicists at the conference, such as Andrei Linde (Stanford) and Steven Weinberg (University of Texas), it does — giving us real information about the existence of larger realms we cannot observe. Weinberg applies it in particular to why Einstein's cosmological constant has a value that allows stars, planets, and life to exist. To opponents, this is quasi-religious tail-chasing and hand-waving. David Gross (University of California at Santa Barbara) described it as a disease: "Anthropic reasoning is a kind of virus," he said. "It infects people, and once infected they are lost forever." The anthropic principle, and its growing influence on the outer shores of cosmology, will be explored in an upcoming issue of Sky & Telescope.         URL: http://skyandtelescope.com/news/article_1079_1.asp