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Science, Philosophy or Science Fiction?
on 2 September 2012
Brian Greene has made first impressions with "The Elegant Universe" (book and DVD), which were quite successfull. Greene has a very alluring, even thrilling way to convey his knowledge and conclusions to a broad audience.
Already in his first oeuvre, he revealed a talent for most unusual examples to underline his statements, occasionally leaving the realm of classical physics. It was there and then when a few scientists, among them Sheldon Glashow, asked the question whether this [string theory] was science or a philosophy, and I like to repeat that question.
With his book (the DVD is imminent) "The Fabric of the Cosmos", it seems that Greene, like many other theoretical physicists, succumbs to the appeal of mathematics, only too often raising ideas that violate the classical and still very valid laws of physics. Examples are numerous:
1: Having studied thermodynamics a couple of years ago, I still recall that the time arrow is the core of the entropy, and most likely the only physical law that provides this confirmation. Besides the ones Greene describes, there are countless examples which support, each and every single one of them, the increase of entropy with time; the ultimate fate of the universe is likely to be the last (and quite dark) one.
Nevertheless, even suggesting that the entropy increases "backwards in time" is a challenge, which would need to be supported by a physical process showing that there is any realism, any reflection of nature to this. Just showing a graph with this statement is most certainly not enough. There is no known way in nature that a physical system could have a higher entropy in the past than at present (or in the future). The possible interpretations of the displayed graph would reach even further, but this would go too far here.
There is definitely no time symmetry for the entropy. Despite the mathematical treatment and the infinitesimally low probability of a splattered egg re-assembling all by itself, any reasonable interpretation of the mathematics would necessarily yield the conclusion that the entropy could "at best" be unchanged, but will increase on any significant level with the flow of time.
A similar "success" would have been the attempt (in the "Quantum Café" ["The Elegant Universe"]) to penetrate a wall.
Both cases seem a bit like what it might be in hell: To try something for an eternity without success.
So: Why propose something like this in the first place?
2: As far as time's arrow is concerned:
Why not consider the cause-effect-relation?
As far as I remember, this is being considered the accompanying explanation for time's arrow (and one reason for the Planck-time).
3: Greene has gone deeper into the subject of the inflation, this very short expansion of space at superluminal speed in the very first instances (Planck times) of the Big Bang.
The basic idea, introducing the inflaton field, fits just fine, but leaves two major issues unresolved:
- How could this energy nucleus expand with a speed orders of magnitude faster than light?
- What made it start / stop, and why did it solve the information question of the homogeneity of the temperature distribution?
(The primordial plasma formed and cooled down until 379000 years after the Big Bang, containing the very temperature fluctuations that later resulted in the structures of the universe we see today.)
A supplementary question:
Why dismissing quantum entanglement, having the universe's master quantum as the source for all required information throughout the cosmos?
Greene considers some rather small nugget of inflation energy to be able to expand, enhancing the energy in the process.
What happened to the conservation of energy?
Is there any hint or even evidence to assume that inflation had to take energy from the gravity potential?
Is it really so far fetched to consider that we have a fifth form of force on our hands, which is likely to be observed even today, as the cosmos is expanding at accelerated rate?!
Has it ever been considered to take a much closer look at the "vacuum energy", which is assumed to have more energy per cubic meter than the entire observable universe?
4: Looking closely at the cosmic background radiation, I believe that there is an important observation that doesn't match the mainstream interpretation.
The left "end" of the displayed graph shows a measured value clearly below the graph, indicating a noticeable deviation from the ideal curve. This has been noted by other physicists
as well, but to my knowledge never been analysed, as this "bend" cannot be explained (yet).
5: With the graphical introduction of the M-theory, it appears that this M-theory is just another (6th) string theory. However, as Ed Witten has described it, M-theory integrates the previous five ones (using an ear, the trunk and the tail of an elephant as elements of the previous string theories, while we are now looking at the entire elephant).
Does this imply that as of now, M-theory is a different, independent string-theory?
6: With the brane model of the cosmos, already given in "The Elegant Universe", Greene suggests that the universe might have been released by a "Big Splat".
How would a splat release a quantum-sized Big Bang?
When slapping your hands together, there is more area involved than when you just "slap" your fingertips.
On the other hand, this splat would provide an explanation for the information "paradox", as such information would be spread out immediately.
Are we to assume that such a splat does not occur simultaneously, but at slightly independent locations on the brane(s)? In this model, it would explain multiverses (parallel universes) very nicely indeed.
7: When describing gravitational waves, I think many people won't get a correct impression on the magnitudes involved. This started with Greene's suggestion of a "gravity phone" ("The Elegant Universe" [DVD]) and continued right now, suggesting that we might be able to measure gravity waves from supernovae. However, neither LIGO nor GEO (nor others) have captured such a gravity wave, nor has either of the binary pulsars been "seen".
Einstein has predicted that gravity waves would hardly ever been measured, and this just might come true, unless we see the merging of two pulsars (or black holes).
Despite the very high energies released by supernovae or (even more so) by binary pulsars/ neutron stars, the stiffness of space prevents any significant effect to be measured.
Would it not be worthwhile to communicate such insights to the publlc?
8: When considering that space and time might be fundamental concepts on their own, this touches a very sensitive point. Inflation, both from the Big Bang and looking at the
expansion of space, most likely beyond the Hubble horizon, might imply that spacetime and matter could "decouple", as matter and energy decoupled shortly after the Big Bang. I've often heard versions of this idea, one of whom being Michio Kaku, who mentioned that when saying, nothing can exceed the speed of light, this literally means "nothing", i.e. empty space.
Question is: Can we, as of today, consider space as being empty, considering a Higgs-"ocean" permeating space (and knowing that Higgs bosons do have a noteworthy mass)?
9: The idea of a "holographic universe", based on the entropy of a black hole as being described by its event horizon (hence, a 2-dimensional sphere), should be used to look at our long-sought higher dimensions rather than trying to describe our indeed 4-dimensional spacetime or 3-dimensional space. It might just be that some insights could be gained, supporting some issues on higher dimensions in string theories.
Question is, of course, would the holographic way be possible at all, considering that the origin of the idea stems from a 3-dimensional entity with maximum entropy, whereas our universe should be considerably far away from this state?
10: When closing "The Elegant Universe", I hoped for further insights on the "programming" of the cosmos, i.e. how are the (40) constants of nature and their laws "imprinted"?
With Greene's previous description of string theories, I hoped that there would be some progress in resolving such essential questions.
Unfortunately, nothing has been mentioned along these lines. Is it because there is no research any more to deal with this?
(The "temperature paradox" might be the top of the list and a "representative" of the entire area. However, the approach to solve this question just by the inflation does not seem to be convincing, as it just shifts the question to another situation within the Big Bang framework.)
11: It appears that many scientists are still craving for symmetry; this ancient, yet still evident quest for everything "round". The Earth being a disk, then a sphere (of course, a perfect one), the Earth at the center of the universe, all stars and planets on spheres around it, later on just the shift in perspective, but still the quest for simple, yet "perfect" geometry, up to the sought-for symmetry of nature from the very beginning (including the symmetry of physical laws).
However, is it so big a problem to acknowledge that we are the result of a faint, but yet existing break of this perfect symmetry?! With such perfect symmetry, neither of us would be here.
(It appears to be a mental scotoma to some extent.)
12: Is it so difficult to consider a fifth force, the inflation (or inflaton field)?
In the period of the Big Bang, it might well have been the long sought "Grand Unified Force", which would be the first acting force of the universe, and one which is still acting today.
Sometimes called "negative pressure" (which would mean suction), which is not what this force actually does (as it really pushes, i.e. exerts a pressure), it would seem that it is a function of the "vacuum energy". As observation shows, the pressure (the inflation?!) is predominantly
effective in the voids, pushing galaxies ever further away (and perhaps even holds them together, as it is assumed for the dark matter).
The strength of the energy should not be a problem, considering the amount of energy predicted by Quantum Electrodynamics. However, this amount would need a "damping"
element, as the full force would most likely tear the cosmos apart.
As far as I see, there is no research in this area, which I cannot understand at all.
13: (Last, but not least):
Why is there no mention of the description of a black hole in string-theory, including a rough, preliminary sketch of the Big Bang, as proposed by Samir Mathur, a lecture held at the CERN about a decade ago? Apart from the description in loop quantum gravity, this model also - finally - avoids singularities.
To come back to the question in the header:
This is science fiction to some and philosophy to a larger extent. Ignoring essential physical laws certainly has an impact on the overall work.
Nevertheless, my conclusion (and recommendation, if you like) would indeed be to acquire this book, as it offers many points for further study. However, it should be read with appropriate care ("distance") and readiness to doubt every idea at least once.