Once Before Time - Martin Bojowald [157]
4. The model was later evaluated further by Ellis with Jeff Murugan and Christos Tsagas.
5. In a different version, this solution was repeated later by Luca Parisi, Marco Bruni, Roy Maartens, and Kevin Vandersloot.
6. A more complicated possibility is that the universe might have come into existence some finite time ago according to a classical concept of time, yet always have existed in the sense of quantum evolution. Resolving this paradox requires an understanding of the subtle difference between classical and quantum time and, eventually, a complete understanding of time itself. Such issues, which are fraught with not only technical but also conceptual problems, are still being worked out. At present, it is indeed conceivable that loop quantum gravity in general might give rise to such a chimerical view, in which both cyclic and linear features are present, as already indicated by cosmic forgetfulness; independently, those types of models could resemble a spontaneous inflationary initiation of the universe in the sense proposed by Sean Carroll and Jennifer Chen. Fundamentally, however, in loop quantum cosmology there always seems to be a quantum universe before what classical gravity would see as the singularity.
7. Please refer to note 1 for chapter 6.
10. THEORY OF EVERYTHING?
1. “That which tempts one to regard all philosophers half-distrustfully and half-mockingly is not the oft-repeated discovery of how innocent they are—how often and easily they make mistakes and lose their way, in short, how childish and childlike they are—but that there is not enough honest dealing with them, whereas they all raise a loud and virtuous outcry when the problem of truthfulness is even hinted at in the remotest manner. They all pose as though their real opinions had been discovered and attained through the self-evolving of a cold, pure, divinely indifferent dialectic (in contrast to all sorts of mystics, who, fairer and foolisher, talk of ‘inspiration’), whereas, in fact, a prejudiced proposition, idea, or ‘suggestion,’ which is generally their heart’s desire abstracted and refined, is defended by them with arguments sought out after the event. They are all advocates who do not wish to be regarded as such, generally astute defenders, also, of their prejudices, which they dub ‘truths’—and very far from having the courage of the conscience that bravely admits this, exactly this, to itself, very far from having the good taste of the courage that goes so far as to let this be understood, be it to warn friend or foe, be it in cheerful confidence and self-ridicule.” (Friedrich Nietzsche, Beyond Good and Evil). Examples can be found also in quantum gravity. Quantum cosmology in particular, a field of comparatively undemanding mathematics with considerably higher stakes, has seen fearless struggle. Fortunately, in physics there is the conscience of experimental observations, powerful enough to command an end to overboiling theoretical heart’s desires.
2. Physicists are hangmen: Our most noble, though unpopular, job is to kill those theories that have no right to exist. But most physicists are sentimental; they often fall in love with their victims. And the task only gets more complicated if a condemned theory happens to be one’s own brainchild. The cute and charming ones, particularly, can easily survive well past their allotted expiration date.
3. Friedrich Nietzsche, On the Genealogy of Morality, Preface, §6.
11. THE LIMITS OF SCIENCE AND THE NOBILITY OF NATURE
1. Science, like so much else, works best in a democratic setting. How well this is realized in a subfield depends to a large extent on the ethics of its leaders. Some are