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Introduction To Online Text by Christopher Stubbs

An anthropic, accidental universe?

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Figure 8: LUX Detector.

The long term goal of the reductionist agenda in physics is to arrive at a single, elegant, unified "theory of everything" (TOE), some mathematical principle that can be shown to be the single unique description of the physical universe. An aspiration of this approach is that the parameters of this model, such as the charge of the electron, the mass ratio of quarks to neutrinos, and the strengths of the fundamental interactions, would be determined by some grand principle, which has, so far, remained elusive.

In the past decade an alternative point of view has arisen: that the basic parameters of the universe come about not from some grand principle, but are instead constrained by the simple fact that we are here to ask the questions. Universes with ten times as much dark energy would have been blown apart before stars and galaxies had a chance to assemble, and hence would not be subjected to scientific scrutiny, since no scientists would be there to inquire. Conversely, if gravity were a thousand times stronger, stellar evolution would go awry and again no scientists would have appeared on the scene.

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Figure 9: Andreas Hirstius with some CERN computers.

The "anthropic" viewpoint, that the basic parameters of the universe we see are constrained by the presence of humans rather than some grand physical unification principle, is seen by many physicists as a retreat from the scientific tradition that has served as the intellectual beacon for generations of physicists. Other scientists accept the notion that the properties of the universe we see are an almost accidental consequence of the conditions needed for our feeble life forms to evolve. Indeed, whether this issue is a scientific question, which can be resolved on the basis of informed dialogue based upon observational evidence, is itself a topic of debate.

Exploring the anthropic debate is arguably a sensible next step, following the dark energy discussion in Unit 11.

Welcome to the research frontier.

Enjoy.