I see little to be hopeful about the new year, but had a glimmer of a hope that we’ll see a reduction in Multiverse Mania. Surely people will sooner or later get tired of stale pseudo-science. Just got back to work from vacation and it seems that so far this is not working out at all, quite the opposite.
At the yearly Edge question site, Martin Rees’s answer to the question “What scientific term or concept ought to be more widely known?” is The Multiverse, and he starts out with the usual sort of breathless hype:
An astonishing concept has entered mainstream cosmological thought…
Critics of the multiverse are described as having two arguments:
- “Some claim that unobservable entities aren’t part of science.”
- “Some physicists don’t like the multiverse: they’d be disappointed if some of the key numbers they are trying to explain turn out to be mere environmental contingencies governing our local space-time patch—no more truly “fundamental” than the parameters of the Earth’s orbit round the Sun.”
The first of these is the usual straw man argument, painting multiverse critics as too ignorant to realize that much of science is based upon indirect evidence, not direct observation. The actual argument of this sort against the multiverse is not that we can’t get direct evidence for it, but that there is no evidence of any kind for it, direct or indirect, and no plausible prospects of getting any. This case has been made ad nauseam here on this blog.
The second of these arguments is treated in much more detail in a new article at Nautilus by string theorist Tasneem Zehra Husain with the title Even Physicists Find the Multiverse Faintly Disturbing. Husain treats in detail the question of how physicists “feel” about the multiverse, and like Rees, makes the point that what physicists don’t “like” about the multiverse is that it removes hopes of being able to do things like understand the nature and strengths of fundamental forces, or calculate the masses of elementary particles.
Rees tells us that physicists are wrong to feel this way, that instead they should be awed by “the revelation that physical reality was grander and richer than hitherto envisioned” and that “If we’re in a multiverse, it would imply a fourth and grandest Copernican revolution.” Husain in the end seems to agree, quoting Gian Giudice:
Perhaps we need to let go of something we’re holding onto too tightly. Maybe we need to think bigger, refocus, regroup, reframe our questions to nature. The multiverse, he says, could open up “extremely satisfying, gratifying, and mind-opening possibilities.”
Of all the pro-multiverse arguments I heard, this is the one that appeals to me the most. In every scenario, for every physical system, we can pose infinitely many questions. We try to strip a problem back to the essentials and ask the most basic questions, but our intuition is built upon what came before, and it is entirely possible that we are drawing upon paradigms that are no longer relevant for the new realms we are trying to probe.
The multiverse is less like a closed door and more like a key. To me, the word is now tinged with promise and fraught with possibility. It seems no more wasteful than a bower full of roses.
Rees and Husain do a good job of showing that if science is about feelings, then Multiverse fans have a fine argument against critics arguing based on their negative feelings. The problem of course is that science is not about feelings but about evidence. The argument by critics that needs to be addressed is that there is no evidence at all for current multiverse scenarios, and no plausible way of getting any by scientific methods.
Nautilus has another multiverse-related piece just out, We Have Pushed Physics Too Far, by Marcelo Gleiser. My reading of the piece is that Gleiser agrees that the Multiverse is not successful science (“Parallel universes are a non-answer”), and I believe most physicists also agree. Unfortunately the lessons he draws from this (as I’m afraid many others are doing) is that the problem not a particular research program that failed (string theory, by ending up with the string landscape and the multiverse), but the whole idea of pursuing mathematical ideas about further unification:
We can call this the ultimate Platonic dream, the quest for a single simple and broad-ranging theory of physics. Indeed, during the past four decades, the search for such a theory has inspired many of the brightest physicists in the world. But today we are seeing the limits of this Platonic thrust to mathematize nature, due to a lack of experimental validation and several theoretical obstacles—including the possibility of multiple universes and the troubling questions they pose.
Gleiser sees successful physics as “an expression of intellectual humility”, with our current problem that of Icarus, trying to fly too close to the sun. I strongly disagree with him about this, seeing some of the best of physics as an expression of intellectual arrogance, not humility. It is intellectual arrogance that has gotten our understanding of nature as far as it has gone, and it will require intellectual arrogance to go farther. The current problem of theoretical physics is due not the sin of arrogance, but to a somewhat different one, that of refusing to admit error. Multiverse mania is largely about the refusal to admit that string theory unification is a failed idea. Yes, arrogance is one reason for this refusal, and admitting failure takes some humility. But then moving on to find different, more successful ideas will require a lot of both mathematics and intellectual arrogance.
Update: One more article at Nautilus about the multiverse. At least this one is explicitly theology, it explains:
a section of liturgy recited whenever we take the Torah out of the ark, and it’s related to a prayer that many Jews know, “Adon Olam.” The phrase is usually translated as “Sovereign of the Universe,” where the word olam can mean both “the universe” and “eternity,” expressing tremendous expanses of both space and time. But in this particular section of the Torah service, God is called “Adon Olamim,” where the suffix -im makes the word plural. This means that God is “Sovereign of the Universes,” as in, “more than one universe.” God doesn’t need to be a designer who had a specific plan in mind that led to the creation of humanity. God is, in fact, the Sovereign over all the universes, including the ones that don’t have life in them.
Update: Yet more explicit theological coverage of the Multiverse at science magazine Nautilus, with an article from Mary-Jane Rubinstein, a professor of religion, who is interested in multiverse versions of pantheism and explains:
As a professor of religious studies, I am particularly drawn to the places where religion and science seem antagonistic, but turn out to be entwined. The multiverse, I would argue, is one of those places.
My only disagreement here would be whether being a place where science and religion are intertwined is a good or bad thing…