Einstein removed the idea of Time from physics, rendering
it an artifact of our conscious. Professor Smolin proposes a different approach
to the definition of reality with Time as a real thing, and Space is an
artifact.
Science depends on predictions and repeatable, testable,
falsifiable results. When assembling a theory that encompasses the entire
universe you have a problem with repeatability—a single universe limits your
sample size. In addition, any “lab” experiment we do will only be on an “isolated
system”, while the real world is an “open system”. So those experiments test
only approximations.
The two predominant current theories in Physics are String
Theory and Quantum Mechanics. Are they enough to explain the universe? That is,
can they “scale up” to become Theories of Everything?
From String Theory it can be derived that for a finite
number of universes (around 10^{500}) the cosmological constant is
positive. In our universe the cosmological constant is positive, so we could
exist in any one of those universes with some random probability. This result
is pretty much what we expect from String Theory: useless confirmation of what
we already know, with no prediction and no chance of falsification. However, a
few years ago it was also derived from String Theory that when you figure out
how many universes would have a negative
cosmological constant, the number is infinite. Simply by random chance a
universe would have an infinitely greater chance of a negative constant. So
either we are extremely lucky, or String Theory is wrong.
Quantum Mechanics is basically a method of conducting
experiments—the choices the experimenter makes influences the reality of the
system being studied. But at the cosmological scale, who is the observer?
We get three clues about nature from Quantum Physics:
incompatible questions (i.e., simultaneously measure position and momentum),
entanglement (pairs of quantum systems can share properties while each system
remains individually indefinite – you can ask a question about the pair that
has an answer but the related question to one of them does not), and
nonlocality (as long as neither “half” of an entangled system interacts with
another system, each can separate and move a great distance apart).
Both of these are “approximate theories” in the sense that
they “truncate” how “accurate” they are. For example, Newtonian Mechanics is an
approximate theory and as far as it went, an “effective” theory.
What must be true for a Cosmological Theory:
·
Any new theory must contain what we already know
about nature
·
The new theory must be scientific (testable,
etc)
·
The new theory should answer they “Why these laws” question. In particular, the
values of fundamental constants
·
The new theory should answer the “Why these
initial conditions” question. That is, why our universe has its properties
rather than those of an alternate universe
·
The new theory should not have to assume
symmetries nor conservation laws
·
Principle of explanatory closure – no chain of
explanation points outside the universe
·
Principle of sufficient reason – there should be
an answer to any reasonable question we ask – does the new theory increase the
number of questions we can answer
·
Principle of reciprocal action – nothing in the
universe acts on other things without itself being acted upon
·
Principle of No Isolated Systems – there’s no
such thing as a system in nature that’s isolated from influence by the rest of
the Universe
·
Identity of the indiscernibles – two things that
have the same relationships with everything else in the universe must actually
be the same thing – this implies there can be no symmetries
·
Physical variables should describe evolving
relationships between dynamical entities. There should be no fixedbackground
structures (including fixed “laws of nature”)
·
We can create (from entanglement) novel
properties in nature
·
Principle of Precedence – the future (that is,
the way the universe is expected to behave) resembles the past (i.e., physics
is caselaw)
·
Conway/Kochen theory of quantum “freewill”– for
entangled, then separated systems that are then tested by experimenters who can
“pick” their measurements, the “response” of those systems is also “free”
·
Principle of maximal freedom – quantum mechanics
describes a universe in which you can make probabilistic predictions, but those
systems have the maximal freedom as would be expected with probabilistic
predictions
·
Principle of before and after – if you make a
prediction and then test it, implicitly time exists to distinguish between
before the experiment/test and after
Time is real
The artifacts of Quantum Mechanics, entanglement and nonlocality,
indicate it is a truncation applicable to small, isolated systems. Restoring
the reality of time makes a new formulation of Quantum Mechanics possible.
We cannot locate an object at a point unless we have some
way to specify that place. If there were two identical objects then there must
be two identical places in the universe. Similarly there can not be two events
in spacetime that have exactly the same observable properties. Thus every
moment of time, and every place at every moment, is uniquely distinguishable.
Different “kinds”
of time:
·
Cosmological arrow of time – universe is
expanding
·
Thermodynamic arrow of time – left to their own,
things become more disordered
·
Biological arrow of time – living things are
born, grow up, and die
·
Electromagnetic arrow of time – what we “see” is
the world from “the past” (light is “old” when it gets to us)
·
Gravitational arrow of time – gravity waves move
to their effects take time to propagate
·
Blackhole arrow of time – absence of black
holes in the early universe
What if “local space” is not what you can walk to next
door, but what is “on the other end of your phone”? This is the idea of Disordered
Locality and the Nonlocal link, in which Space is an emergent phenomenon, as
seen in nonlocality and entanglement.
At the fundamental level of description, at which instead
of “space” there is a network of interactions with everything potentially
connected to everything else, then quantum theory and space emerge together.
Summary of differences:
Space is Real

Time is Real

Time is an illusion. Truth
and reality are timeless

Time is the most real aspect
of our perception of the word. Everything that is true and real is such in a
moment that is one of a succession of moments

Space and geometry are real

Space is emergent and
approximate

Laws of nature are timeless
and inexplicable, apart from selection by the anthropic principle

Laws of nature evolve in time
and may be explained by their history

The future is determined by
the laws of physics acting on the initial conditions of the universe

The future is not totally predictable,
hence partly open

The history of the universe
is, in all its aspects, identical to some mathematical object

Many regularities in nature
can be modeled by mathematical theories. But not every property of nature has
a mirror in mathematics

The universe is spatially
infinity. Probabilistic predictions are problematic, because they come down
to taking the ratio of two infinite quantities

The universe is spatially
finite. Probabilities are ordinary relative frequencies

The initial singularity is
the beginning of time (when “time” is defined at all) and is inexplicable

The Big Bang is actually a “bounce”
which is to be explained by the history of the universe before it

Our observable universe is
one of an infinite collection of simultaneously existing of unobservable
universes

Our universe is a stage in a
succession of eras of the universe. Fossils, or remnants, of previous eras
may be observed in cosmological data

Equilibrium is the natural
state and inevitable fate of the universe

Only small subsystems of our
universe come to uniform equilibria; gravitationally bound systems evolve to heterogeneous
structured configurations

The observed complexity and
order of the universe is a random accident due to a rare statistical
fluctuation

The universe naturally
selforganizes to increasing levels of complexity, driven by gravitation

Quantum mechanics is the
final theory and right interpretation is that there are an infinity of
actually existing alternative histories

Quantum mechanics is an
approximation of an unknown cosmological theory
