Last month Amanda Gefter opined in New Scientist that when it comes to explaining the fine-tuning of the universe “It Isn’t as Simple as God vs the Multiverse.” She was referring to recent comments made by Steven Weinberg and Tim Folger to the effect that cosmic fine-tuning can only be explained by a supernatural cosmic designer or a multiverse. While Gefter thinks the multiverse hypothesis is a good one, she takes exception with this dichotomy as being unscientific:
There are plenty of reasons to take the multiverse seriously. Three key theories – quantum mechanics, cosmic inflation and string theory – all converge on the idea. But the reason physicists talk about the multiverse as an alternative to God is because it helps explain why the universe is so bio-friendly. From the strength of gravity to the mass of a proton, it’s as if the universe were designed just for us. If, however, there are an infinite number of universes – with physical constants that vary from one to the next – our cosy neighbourhood isn’t only possible, it’s inevitable. But to suggest that if this theory doesn’t pan out our only other option is a supernatural one is to abandon science itself.
How so? According to Gefter it is because “science never boils down to a choice between two alternative explanations. It is always plausible that both are wrong and a third or fourth or fifth will turn out to be correct.” While I would object to an absolutist interpretation of “never,” in general I would agree that in principle, at least, there could be explanations of the cosmic fine-tuning other than a supernatural creator or the multiverse.
But what might they be? After all, the reason folks like Weinberg and Folger have reduced the debate to a dichotomy between a supernatural creator and the multiverse is because to-date, no other explanations fit the data. Gefter postulates that maybe we “endow the universe with certain features by the mere act of observation. … [O]bservers are creating the universe and its entire history right now. If we in some sense create the universe, it is not surprising that the universe is well suited to us.” What is surprising, however, is the fact that Gefter entertains this wild and incoherent speculation as a rational, scientific possibility (in her own words, “That’s speculative, but at least it’s science.”).
To say we create the universe through our observation is to say we cause the universe (including its past and present forms) to exist, and to exist in a certain way. But this is absurd for several reasons:
- It would require backward-causation, in which present causes (our observations) produce historical effects. What philosophical or scientific reason is there to believe this is plausible, yet alone possible?
- If our act of observation is the sufficient cause of the universe’s existence, then prior to our observation (the cause) there was no universe (effect). If there was no universe, what were we observing? Nothing. If there was nothing to observe, there was no effect to affect.
- Where did observers come from? If, for observers to exist, the universe must be finely-tuned to produce them, then the universe must precede its observers both causally, logically, and temporally. If a finely-tuned universe must precede its observers, then it is the cause of us-we are not the cause of it.
- If observers cause the universe to exist, and the universe in turn causes observers to exist, then we must exist prior to existing, which is incoherent.
- If observers endow the universe with certain features by the act of observation, and observers observe different (and sometimes conflicting) things, why isn’t the universe endowed with different laws, and a different history simultaneously? Why doesn’t the universe have an eternal past when observed by a proponent of the Steady-State model, and a finite past when observed by a proponent of the Big Bang model? If the universe is a real existent, it cannot be both eternal and past-finite simultaneously. One of the observers must be mistaken. If that observer cannot alter reality by his observation, then it follows that our observing the universe has no causal relationship to the universe.
Far from demonstrating the inadequacy of the creator-multiverse dichotomy, Gefter confirms it. If the dichotomy can only be avoided by postulating something so absurd as the notion that we create the universe by observing it, surely it is more rational to stick with the dichotomy.