Astronomy - September 2015

300–500 million years

Billions of years

13.8 billion years

One

dimension

Two

dimensions

Three

dimensions

Four

dimensions

Time

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ASTRONOMY: ROEN KELLY,

AFTER ESA; NASA/ESA/

HUBBLE HERITAGE (STScI/

AURA) (GALAXIES)

WWW.ASTRONOMY.COM 31

String discord

A different multiverse involves string theory. Originally,

theorists postulated tiny strings along with many hypoth-

esized extra dimensions as a hopeful way to explain the

four fundamental forces — gravity, electromagnetism,

and the strong and weak interactions — and the standard

model of particle physics.

It has not succeeded. Beyond the utter lack of evi-

dence for extra dimensions, it does not predict our uni-

verse, nor can it explain the accelerating expansion of

the cosmos discovered in 1998. So it’s increasingly

viewed as a failed theory. But it does “predict” 10^500 dif-

ferent ways reality can materialize. This itself is vague to

the point of useless.

A very different multiverse is based on quantum theo-

ry’s many worlds interpretation (MWI).

We’ve known for over 80 years that the act of observa-

tion can alter experimental results. But why? Moreover,

why does an electron, when it comes to a fork in the road,

go one way and not the other?

The MWI, a mainstream if minority interpretation of

reality, claims that every choice in nature creates a sepa-

rate universe that then breaks off from the others and

continues on. If you turn left at an intersection instead of

turning right, another “you” materializes who does indeed

turn right. An entire new universe continues with that

reality permanently enshrined. You are never aware of any

other universe but the one you know, and the same is true

of all the other yous that made other choices.

Separate universes even sprout up when a leaf falls here

and not there, a few inches away. Many worlds’ multi-

verses thus keep increasing their numbers wildly.

STRING THEORY AND THE

MANY WORLDS INTERPRETATION

FIRST STARS FORM

Stars and galaxies form in

the densest knots.

DARK AGES
Atoms feel gravity
from a cosmic web
of dark matter.

GALAXY

EVOLUTION THE PRESENT UNIVERSE