Natural Science Forum / Physics / Relativity / November 2005

In refutation of Tim's argument below I quote Igor Novikov. Of course
one must read Novikov to get all the details properly.

In reference to Tim's "paradoxes" below:

"Does this paradox demonstrate that time travel [to the past] is
impossible? Not at all. The reason is that in our discussion of the
paradox [same as Tim's below] I committed a serious logical error. I
discussed the situation twice, in two different ways. In the first
discussion, I discussed my journey to mouth B assuming there was no
meeting with the older version of myself from the future. In the second
discussion. I discussed the same journey but assumed that the first
discussion was correct and that therefore I could travel back in time
and that therefore I could travel back in time and that therefore there
was a meeting. The error is the assumption in the first discussion that
there was no meeting. If the meeting happened, it happened. So we should
take into account the consequences of the meeting from the very
beginning. Therefore, even if I am not killed, when I travel into mouth
B, then I will remember the meeting with my younger self when I come out
of mouth A. So what actually happens ... We see now that there are no
contradictions or paradoxes ... Events can be influenced by other events
in the future, as well as other events in the past ... however there is
only one flow of events, so the past cannot be changed once it has
occurred ... in the presence of time machines we have very strange and
unusual physical processes taking place, but no contradictions. ... This
means that our free will must be constrained. If I meet with a younger
version of myself and wish to kill that younger version, then the laws
of physics will prevent me from doing so."

Star Gates and Time Travel to The Past (from my 4th book "Star Gate")

The words “Star Gate” and “wormhole” mean the same thing in this book.
More precisely I mean “traversable wormholes” without any black hole
event horizons. These star gates require anti-gravitating “dark energy”
to keep them stable and open. Since our universe is about 73% dark
energy on the large scale there is plenty around.  Any ETs
(Extra-Terrestrials) visiting Earth in their flying saucers are able to
do so because they know how to manufacture and also use naturally
occurring wormholes that may have been created in the early universe and
are time travel machines to the past Stephen Hawking’s “chronology
protection conjecture” noted but dismissed because of the facts. Are
time machines are dangerous weapons of mass destruction in the wrong hands?

“If someone could travel from our time back into the past, then that
person could probably change the past. If so, as a result, he would
change all of subsequent history. For example, a person who travels back
in time to the beginning of the universe could change the physical
conditions at that period, and as a result change the whole history of
the universe. The explosion of a hydrogen bomb is nothing compared to
such a possibility.”  Moscow physicist Igor Novikov at Cal Tech Kipfest
2000.[i]

However, we do not have to worry about changing the past. Novikov proves
that is based on faulty logic and that in every case a strange but
self-consistent global loop in time happens.  We do not have absolute
free will to violate the laws of nature. It may be our free will to fly
if we walk off a cliff, but we will fall.  Similarly, you may go back in
time and attempt to make a paradox, but you will fail to do so.  Simple
models of a billiard ball going back in time to collide with its younger
self have consistent histories. If there is a collision it will be a
very weak glancing collision that will allow the ball to pass through
the wormhole time machine. If the ball is a bomb that explodes at least
one fragment from the explosion will go through the time machine to make
the ball explode in the first place. If it happens it happens.  If you
go back in time to meet your younger self you will remember meeting your
younger self as you enter the time machine and you will not be able to
prevent yourself from doing so. Jean Cocteau’s film “The Last Testament
of Orphee” dramatizes this idea as does the film “La Jetee” and “Twelve
Monkeys” as well as “The Terminator” series with Arnold. Here the
science fiction is actually good physics.

[i] “The Future of Spacetime” ed. Richard Price, p. 58, W.W. Norton (2002)

On Nov 29, 2005, at 4:17 PM, ...Timothy ...wrote:

Well, the math is going to send me back to school, of this I have no
doubt!  However, please let me suggest a couple of intriguing thoughts.
Time travel, itself, presents well known paradoxes; Dr. Mallet, himself,
acknowledges and has suggested ways to avoid.

No, this is a Red Herring. It's simply not true at all. The refutation
of what you just wrote is in "Can we change the past?" by Professor Igor
Novikov given at the Cal Tech Kipfest 2000 printed in "The Future of
Spacetime" 2002 California Institute of Technology ISBN
0-393-32446-X-pbk  pp 57-86.

The notion of such autocidal paradoxes is based of faulty logic and
actual physics calculations show that such arguments are not correct.

  We are all familiar with
it, but I describe the paradoxes as Time Loop and Grandfather Paradoxes;
I actually express them in terms of logical argument.

You are simply wrong. If you read Novikov's simple article you will see
why. :-)

  The Grandfather
Paradox is the well known situation in which one eliminates one's own
cause, and the Time Loop Paradox is where one multiplies an existing
cause (thus creating numerous copies of a result).  The logical
expression is the Clarity Principal of Logic, where P must imply P and
NotP must imply NotP.  In both cases, P implies NotP (thus violating the
principal); the Grandfather Paradox creates an implication of P implies
Zero and the Time Loop Paradox implies P implies MultipleP (which is a
form of NotP).  It has been pointed out that identification of paradox
is tantamount to establishing impossibility.

So, that said, what if we were to see if there were any way to
accomplish Time Travel without invoking Paradox?  Dr. Mallet makes an
attempt to do so by suggesting that Time Travel cannot happen prior to
when Time Travel becomes possible.  (Actually, Dr. Carl Sagan made the
same constraint in a PBS-broadcast NOVA interview, some years earlier).
It's a game suggestion, alright, but when I thought about it what I
concluded was that it just didn't cut it.  So, I tried to see if I could
do better.

What I came up with were two constraints:
1.  A time traveler cannot travel to any time in which he has actually
existed

False IMHO

2.  A time traveler cannot be able to interact with himself while inside
an energized time travel field (but cannot, in any case, violate #1,
above)

False IMHO

I also construe a time travel field as being a sort of event-horizon
that effectively creates a condition of non-existence between the inside
of the field and the rest of the Universe.  It essentially decouples
actions inside the field from outside the field, kind of the same way a
worm-hole decouples intervening space from the end-points.

Again read Novikov. Hawking has a paper after his, but not based upon
the kind of
argument you make here. :-)

Now, as you look at my constraints, it's quite possible to say that I've
constrained myself out of time travel.  How is it possible to exist
during a time when you do not exist (constraint 1)?  You can't.  Oh,
wait, but that's the static case.

Now, let's consider the Relativistic case.  The Lorentz equation tells
us that there is a T-prime that is different for travelers at
relativistic velocities which is different from the T of the
non-traveling reference case.  T-prime is always less than T, and this
is very significant at speeds near C.  So, what if, while traveling at
relativistic velocities, you are also inside your time travel field
(effectively traveling along the closed time-like curve and effectively
travel backwards in time)?  Consider the time of T minus T-Prime.  What
if your time field absolutely, always, and consistently, appeared to
deliver you from time T, (which is what an outside observer would say is
the time you took to travel the distance, and cannot be any smaller than
C/distance traveled) to T minus T-prime (which is the time you think you
spent during your travels due to dilation)?  In fact, what if, while
traveling inside your time travel field, you actually never reach time
T, but are always deposited at T minus T-prime; it would somehow be a
function of this type of time travel that T minus T-prime would always
be the result, so no matter what you do, after accelerating up to
relativistic velocity, and turning on your time travel field, the only
point you come out at is a point in time that's T minus T-prime, and
nowhere else?  If no other time is possible than T minus T-prime, than
both of my constraints (above) would be satisfied, and paradox is
eliminated.

Well, after looking at this train of logic, I began to wonder if any of
the EFE solutions would favor or result in either T-prime, or T minus
T-prime.  That is why Mallet's Time Machine Proposal is so intriguing to
me.

You see, guys, if the math works out, than it may not be as much as time
travel that's been discovered it.  It's FTL.