Multiverset og annen kvasivitenskap

Når jeg hører noen snakke om multiverset, er det ikke til å komme forbi at det rykker i skeptikermusklene. Saken ble ikke spesielt bedre da jeg leste Martin Gardners oppgjør med dette i Are Universes Thicker Than Blackberries?: Discourses on Godel, Magic Hexagrams, Little Red Riding Hood, and Other Mathematical and Pseudoscientific Topics , en bok jeg anmeldte i Humanist for noen år siden.

Tendensen til å blande østlig mystikk med moderne vitenskap er i det hele tatt påtagelig hos enkelte skribenter med vannskrekk for kristen tro.

Ikke minst er det lettere interessant når noen til og med omtaler dette som en testbar hypotese. I beste fall er dette en høyst indirekte mulighet, via en mengde om og men og teoretiske betraktninger med araber flikk flakk, i verste fall direkte nonsens.

Hvordan man skal teste noe som tilhører et annet univers, er av de mer spennende laboppgavene som kan gis. Vi får i det hele tatt se an den videre utviklingen i århundrene fremover.

Men siden det nå engang nærmer seg julehøytiden, kan anbefales å følge denne ledestjernen. Her henvises til en av fysikerne som jeg leser med størst interesse, Roger Penrose, som opptar atskillige centimetre i hylla.

Is there a way to test the proposition that we live in a multiverse. Roger Penrose of Oxford University in his book The Road to Reality, pp. 762-5) has argued that if our universe is but one member of an infinite world ensemble of randomly varying universes, then it is overwhelmingly more probable that we should be observing a much different universe than that which we in fact observe.

Penrose calculates that the odds of our universe’s low entropy condition obtaining by chance alone are on the order of 1:1010(123) (this is under the Weyl Curvature hypothesis). The odds of our solar system’s being formed instantly by random collisions of particles is, on the other hand, about 1:1010(60), a vast number, but inconceivably smaller than 1010(123). If our universe were but one member of a collection of randomly ordered worlds, then it is vastly more probable that we should be observing a much smaller universe. Observable universes like that are much more plenteous in the ensemble of universes than worlds like ours and, therefore, ought to be observed by us if the universe were but one random member of an ensemble.

If our universe is but one random member of a multiverse, then we ought to be observing highly extraordinary events, like horses and unicorns popping into and out of existence by random collisions since these are vastly more probable than all of nature’s constants and quantities falling by chance into the virtually infinitesimal life-permitting range. Penrose concludes that multiple universe explanations are so “impotent” that it is actually “misconceived” to appeal to them to explain the special features of the universe. I wouldn’t take as cynical a view as that; I find it conceivable that the cosmos could be much larger than this one universe. But such a view is metaphysics; it is not scientific and it is important to know the difference.

Fristelsen til å forlate vitenskapen er ofte stor når man kommer til spørsmål som har å gjøre med livssyn. Enten man snakker om Snåsamannen eller multiverset.