Time Travel, Non-Causality and
The Evolution of Halacha
Excerpt from “The Retroactive
Universe”
Introduction: Time Travel and Paradox
The possibility of time travel has intrigued
people for generations, however the paradoxes involved seem to rule out many
types of time travel.
Of course we are all time travellers, as we
all move into the future. However, physics actually teaches that one type of
time travel is possible - travelling into the distant future in a short amount
of time. As special relativity shows, the faster one moves relative to any
other body, the greater the elapsed time as measured by the other body. Thus
for example a person moving in a rocket at a speed very very close to the speed
of light for a few thousand years as measured by the earth, will measure one
hour time passage on their own watch, and will age only one hour[1]. Thus, if one wishes to travel to the distant
future, one need only travel quickly.
However, there is no possibility
in special relativity theory of going backwards in time, and therefore the trip
is one-way only according to this theory.
Recently researchers in general
relativity theory have attempted to investigate the possibility of time travel
if a sufficiently advanced technological civilization were capable of forming a
theoretically possible entity known as a 'wormhole'[2].
Travel to the past seems to be
possible using certain types of wormholes. However, if one were to travel to
the past, one could conceivably end up killing one's ancestor or otherwise
changing events, thereby erasing or changing the chain of events leading up to
the trip to the past. These paradoxes have led many to conclude that travel to
the past is impossible, and therefore that wormholes of the type that permit
such travel are actually physically impossible[3].
There are similar paradoxes
which arise when one considers the possibility of information transmission. If
someone were to be able to obtain information about the future, they could in
theory prevent that very event from ever occuring. In addition, any information
which is sent faster than the speed of light will give rise to paradoxical
situations where the information can be used to prevent the information from
being sent to begin with.
Of course any event which is
predictable can be prevented, in which case of course the prediction itself is
changed, so that there is no additional paradox involved in obtaining
information regarding a future event if one postulates that the future is not
fixed. The past would seem to have to be fixed in order for the present to
remain as it is, but if the future is changed then there is no repercussion on
the present, and therefore changing the future involves no inherent paradox.
Knowing the future however implies that there is an already existent future
which cannot change, and this is what involves paradox since the knowledge
obtained about an event occuring in the future can be employed to prevent that
very event from occuring. Therefore knowing the future of non-predictable
events implies that the future is (un?) changeable.
Of interest therefore are those
events which cannot be predicted for one reason or another, with the associated
question of whether such events can be known before they occur without this
involving paradox.
Divine Omniscience and Free Will
Since by definition a creator of
the physical universe is beyond the limitations of physical law, and has
infinite computation ability, all determined events can be predictable to the
creator. Random events may be unpredictable if they are truly random, but it is
also possible that what is random in the physical universe is not random to a
being beyond the realm of physical law.
As to free willed events
however, prior to their occurence there is no means to know what the choice
will be - if it were otherwise it would not qualify as free will. Nevertheless,
in Jewish philosophy it is generally assumed that God does indeed know
beforehand the results of future free willed decisions. Often this
pre-knowledge has been felt to imply that these free willed decisions are
actually determined, and therefore not free.
An interesting approach to this
question was suggested about a thousand years ago by Rav Hai Gaon[4]. According to Rav Hai Gaon, events have to
actually occur in the universe in order for God to have known them in advance. Therefore,
God does not know the outcomes of future free-willed choices because they are
predictable, but rather these future choices are known only because God is
beyond time. Free willed events are truly free and are unpredictable to God,
but those free willed choices which occur at any time during the existence of
the universe are known to God at any other time, including a prior time.
However it is only known because it has been injected into the stream of
reality via the free willed choice of the individual at some point in the
existence of time.
The Evolution of Halacha, and
Non-Causality
The end of the creation account
states that God rested from the work of creation"which God created to
do". According to the Midrash and Zohar, this is a reference to the need
for humanity to complete the creation, which was deliberately left incomplete
in order to allow humanity to form it according to free willed choice, and
creative activity.
There is an additional realm of
incompleteness in the initial creation which is filled-in via human activity
involving free-willed choice and creativity - the development of halacha. In
Jewish philosophy, the guidelines for correct action are determined by halacha,
and it is up to individual free willed choice to decide whether or not the
halachic path will be followed. As situations change, halacha must evolve to
meet the new cases which arise. Halacha is determined by Torah scholars, and
they are guided by intelligence, knowledge, and inasmuch as their opinions may
be affected by natural inclinations and biases or remain free of such taint, by
their free-willed choice.
Metaphysically, the Torah is the
blueprint of creation, and halacha is the fine-print of the blueprint, and
therefore the development of halacha is the detailed filling-in of the
blueprint of creation.
Together with the approach of Rav Hai Gaon,
this idea can help us understand a few interesting statements reflecting the
worldview of the Jewish sages in regard to Halacha.
Although of course the creation
of the world preceded the development of halacha, it was perhaps only because
halacha would be developed as it was that the blueprint of the universe - the
Torah - emerged as it did, and therefore that the universe could be created as
it was.
This gives meaning to the
Midrashic and Kabbalistic statement that God consulted a blueprint in order to
create the universe and that this blueprint was the Torah, implying in some
manner that the blueprint was derived not from God. Indeed in this context one
can attribute the existence of the blueprint to the fact that after the
creation of the universe the development of halacha would procede as it has.
This again is a self-referential non-causal loop, as is the case with all
matters involving free will.
Similarly, according to the
Talmud, Moses received the entire body of Jewish law, all of halacha, at
Similarly, the Talmud relates
relates that God translated Moses in time so that Moses himself attended a
lecture given by Rabbi Akiva. At this lecture, Rabbi Akiva stated that all that
he was teaching originated with Moses - yet Moses himself heard these matters
for the first time! On can then understand this in the same manner: Rabbi Akiva
indeed originated the material, and then this fact allowed the material to
become known to Moses via God prior to Rabbi Akiva's birth, at
The means by which at Sinai
Moses was made aware of all the halachot which would eventually be developed is
generally taken to be via direct transmission from God, as was the case with
the rest of the Torah. However the means by which Moses is made aware of those
matters discovered by Rabbi Akiva may have been by the bringing of Moses
forward in time to participate in Rabbi Akiva's lectures.
Kohelet and Free Will
Introduction
Hundreds of years prior to the
earliest known Greek philosophers, King Solomon wrote and philosophized in
The contemporary civilization to the far east
of
King Solomon grappled with the
competing philosophies, with the wisdoms of the other contemporary
civilizations, but firmly espoused the Jewish philosophy - as can be seen in
the book of Kohelet (Ecclesiastes).
Kohelet: Determinism and Randomness
There are two major themes which
are repeated over and over in this book: the lack of novelty in events,
expressed in the repeating refrain "there is nothing new under the sun",
together with the cyclical nature of history "that which was is that which
shall be"; and furthermore, the meaninglessness of all, expressed in
Solomon's terms (usually translated as "vanity of vanities, all is
vanity") "emptiness and chaos, all is emptiness and chaos."
However, at the end of the long
tirade of despair, and of deterministic and nihilistic philosophising,
Solomon's conclusion is a bolt from the blue, a reaffirmation of the Jewsih
belief in meaning and purpose, in the centrality of free-willed moral choice.
Solomon's Terminology
The word employed in
Ecclesiastes for "vanity" or "emptiness" is, in the
original Hebrew", Hevel". One can relate this word to the word 'tohu'
in the Bible, the word translated as 'emptiness/chaos/void' in the creation
account: "In the beginning, God created...and the earth was empty and
void...", since the words 'tohu' and 'hevel' are employed jointly in the
same context, as we shall show.
Furthermore, one can relate the
word 'hevel' as well as to one from ancient Greek cosmology, the 'hyuli' or
primal chaotic matter from which Ramban says God fashioned the world.
INSERT HERE SECTION on WORD RELATIONS ETC (on
Mac disk: Kohelet article)
= hyuli......tohu va'vohu - hevel vetohu ;
hevel = tohu = randomness. etc.
One can therefore interpret
Solomon's statements to the effect that "there is nothing new under the
sun", and "that which was is that which shall be" as referring
to the tenets of determinism, and his statements "emptiness and chaos, all
is emptiness and chaos" as referring to the idea of the inherent
randomness of the universe. That is, Solomon's treatise deals with the basic
philosophies of meaning in life, as based on underlying metaphysical and
cosmological understandings, philosophies which were later explored by the
Greek philosophers as well as by the civilizations in the far East.
Biblical Philosophy and Free Will
According to Jewish tradition,
although all is determined according to the Will of God, humanity possesses the
ability to freely choose between good and evil. If we assume that this is the
meaning of the Talmudic saying "all is in the hands of Heaven except for
the fear of heaven", then the expresion "the fear of heaven"
must be the Talmudic equivalent of 'free will'. That is, the expression"all
is in the hands of Heaven except for the fear of heaven" means "all
is determined by God, except for the operation of human free-willed
choice".
According to Jewish philosophy,
the Torah is the unique guideline for human action, and provides the model for
the correct application of free-willed choice.
The spiritual essence of
humanity is the soul, the breath of God which is in them, and the physical
essence of humanity is its unique ability to transcend the causal structure of
the physical universe in using free
will.
A succinct expression of Torah
philosophy in exhortatory form could be phrased as "use your free will to
choose the good, that which is outlined in the Torah; for free willed choice is
the essence of what humanity is about, and it is this (using free will to
choose the good) which is humanity's purpose."
At the conclusion of his long excursus into the competing philosophies
of the day - that of determinism and of randomness, after exhausting the
arguments for determinism under the category "there is nothing new under
the sun" and those for random chaos and meaninglessness under the category
of "vanity of vanities, all is vanity", Solomom sums all up, and
concludes with the exhortation:
"And in conclusion, after
all has been said and done, fear God and keep His commandments, for this is the
essence of Mankind" - or, in our paraphrase, "After considering the
philosophies propounding a meaningless existence, those of preordained and
cyclical determinism and those of randomness, chaos, nihilism, after all the
evidence and argumants have been heard, the conclusion is: use your free will
to choose the good, that which is outlined in the Torah - for free willed
choice is the essence of what humanity is about, and it is this (using free
will to choose the good) which is humanity's purpose."
[1] This theory has been tested and verified many times for elementary particles moving at high speeds, and also for macroscopic objects at slow speeds. The theory of special relativity is therefore accepted as fact, not merely as a speculative theory. However, travel to the future in this way is not yet possible as today's rockets are not capable of moving anywhere near the speed of light, and to do so would require vast amount of fuel - perhaps necessitating the equivalent of burning entire stars as fuel.
[2] The mathematical structure of relativity theory as understood today allows the existence of wormholes - whether they are actually physically possible is under contention.
[3] 'Godel universes' contain closed time-lines which may give rise to similar paradoxes. However, clearly if spacetime is a four dimensional manifold, and there is no additional super-time along which the time direction develops, the four-manifold cannot change, and therefore the past and future are fixed. (speculation: leaves, branches, windings etc. of manifold about another, fiber of times above each space point.)
[4] This idea as explained here was described in a footnote earlier in the book.