Even Scientists Get The Blues and Brawls in the Many World Universe

[Guest guest]

One universe or many? Panel holds unusual debate

 

March 30, 2006

Special to World Science

 

Scientific debates are as old as science. But in science, " debate "

usually means a battle of ideas in general, not an actual, politician-

style duel in front of an audience.

 

Occasionally, though, the latter also happens. And when the topic is

as esoteric as the existence of multiple universes, sparks can fly.

 

 

Such was the scene Wednesday evening at the American Museum of

Natural History in New York.

 

Museum staff put together five top physicists and astronomers to

debate whether universes beyond our own exist, then watched as the

experts brawled over a question that's nearly unanswerable, yet very

much alive in modern physics.

 

New universes may appear constantly in a " continual genesis, "

declared Michio Kaku, a theoretical physicist at City College of New

York and key supporter of the idea that there exist multiple

universes, or a " multiverse. "

 

" The multiverse is like a bubble bath, " with a bubble representing

each universe, he added. There are " multiple universes bubbling,

colliding and budding off each other " all the time.

 

Another panelist backed the multiverse idea, but three more insisted

there's virtually no evidence for the highly speculative concept.

 

A brief history of other universes

 

Some versions of the many-universes concept date back to ancient

Greece, said panelist and science historian Virginia Trimble of the

University of California, Irvine. But scientific justifications for

the idea began to appear in the second half of the 20th century, when

U.S. physicist Hugh Everett proposed it as a solution to a puzzle of

quantum mechanics.

 

Physicists in this field found that a system of subatomic particles

can exist in many possible states at once, until someone measures its

state. The system then " collapses " to one state, the measured one.

 

This didn't explain very satisfactorily why the measurement forces

the system into that particular state. Everett proposed that there

are enough universes so that one state can be measured in each one.

Each time someone makes a measurement, the act creates a new universe

that branches off the pre-existing ones.

 

The " multiverse " theory later reappeared as a consequence of another

theory of physics, that of " inflation, " developed by various

physicists in the late 1970s and early 1980s.

 

The theory solved several gnawing problems in the Big Bang theory,

the idea that the universe was created from an explosion of a single

point of extremely compact matter, by postulating that this expansion

was stupendously fast in the first infinitesimal fraction of a

second, then slowed down.

 

As part of this initial superheated expansion, known as the

inflationary period, the universe could have sprouted legions

of " baby universes, " said Andrei Linde of Stanford University in

Stanford, Calif., a panelist at Wednesday's event and a developer of

the inflation theory.

 

A third argument for the multiverse theory comes from string theory,

seen by some physicists as the best hope for a " theory of everything "

because it shows an underlying unity of nature's forces and solves

conflicts between Einstein's relativity theory and quantum mechanics.

 

String theory proposes that the many different types of subatomic

particles are really just different vibrations of tiny strings that

are like minuscule rubber bands. The catch is that it only works if

the strings have several extra dimensions in which to vibrate beyond

the dimensions we see.

 

Why don't we see the extra dimensions? A proposal dating to 1998

claims we're trapped in a three-dimensional zone within a space of

higher dimensions. Other three-dimensional zones, called " branes, "

could also exist, less than an atoms' width away yet untouchable. The

branes are sometimes called different universes, though some

theorists say they should be considered part of our own because they

can weakly interact with our brane in some ways.

 

In part the question rests on definitions, noted Lisa Randall, a

Harvard University physicist who was one of the panelists on

Wednesday night. Different universes can be defined as zones of

spacetime that interact with each other weakly or not at all, she

said.

 

Where's the evidence?

 

Marshalling their best evidence for extra universes, Kaku and Linde—

the two panelists who back the notion—presented a variety of

arguments, which all boiled down to two basic points.

 

One, explained Linde, is that the multiverse solves the problem of

why the laws of physics in our universe seem to be fine-tuned to

allow for life. " If you change the mass of the proton, the charge on

the electron, " or any of an array of other constants, " we'd all be

dead, " he argued.

 

Why is this so, Linde asked— " did someone create this special universe

for us? "

 

Steering clear of the straightforward answer many religious believers

would give, " yes, " Linde argued that the multiverse explains the

problem without resorting to the supernatural. If there are infinite

universes, each one can have different physical laws, and some of

them will have those that are just right for us.

 

The second key argument they presented is the one based on inflation,

a theory considered more solidly grounded than the highly speculative

string theory and its offshoots. The equations of inflation, Kaku

explained, suggest spacetime—the fabric of reality including space

and time—was initially a sort of foam, like the bathtub bubbles.

 

New bubbles could have sprouted constantly, representing new

universes, he added. Linde has argued that this occurs because the

same process that spawned one inflation can reoccur in the inflating

universe, beginning a new round of inflation somewhere else. This

would occur when energy fields become locally concentrated in

portions of the expanding universe.

 

Scientists might one day create a " baby universe " in a laboratory by

recreating such conditions, Kaku said. This would involve

resurrecting the unimaginably high temperatures of the early

universe. A spacetime foam can be recreated by literally " boiling

space, " he said, adding that a sort of advanced microwave oven could

do the trick.

 

Experiments already planned could " test the periphery " of these

ideas, he added including a super-powerful particle accelerator to

switch on next year, the Large Hadron Collider in Switzerland.

 

Randall countered that the new accelerator won't bring particles

anywhere near the level of energy needed to recreate the spacetime

foam envisioned by multiverse proponents. The energies attained will

be lower by a factor of 10 followed by 16 zeros.

 

Lawrence Krauss, a physicist and astronomer at Case Western Reserve

University in Cleveland, said the whole multiverse idea is so

speculative as to border on nonsense. It's an outcome of an old

impulse, which also gave rise to the correct notion that other

planets exist, he argued: " We don't want to be alone. "

 

It also caters to our desire for stability, he added: the universe

changes, but " the multiverse is always the same. " And if there are

many universes, you don't have to make any predictions that will

subject your pet theory to awkward tests, " because there's always one

in which the answers work out. "

 

Krauss allowed that he might buy the multiverse idea if it's a

consequence of some new theory that also successfully accounts for

many other unexplained phenomena. But otherwise, multiverse

concepts " are extending into philosophy " rather than science, he

added, " and may not be testable. "

 

These guys fight like a bunch of non-dualists or something!

.......bob