From: ottoh3@CFSMO.Honeywell.COM (Otto Heuer #3)
Subject: FAQL: TIME LOOPS, YESTERDAY'S ENTERPRISE, AND TASHA YAR EXPLAINED
To: rec.arts.startrek.misc
Posted-Date: Tue, 1 Sep 92 00: 05:00 cdt
Organization: Honeywell Systems & Research Center
Date: Tue, 1 Sep 1992 05:05:00 GMT
Received-Date: Tue, 1 Sep 92 00: 04:49 CDT


       TIME LOOPS, YESTERDAY'S ENTERPRISE, AND TASHA YAR EXPLAINED
			  (last updated 7/9/92)

This posting is intended to cut  down on  the "often  asked questions" that
seem to  pop up  every few  months in  the rec.arts.startrek.misc newsgroup
concerning "Yesterday's Enterprise" and Tasha's life and death.   It is one
of a number of periodic postings posted  to r.a.s.*.   Please  refer to the
"LIST OF PERIODIC POSINGS TO r.a.s.* NEWSGROUPS" article for a full list of
periodic postings.

I've expanded this list a bit more (it originally only explained Tasha Yar)
so if anyone wants to contribute to the new sections, feel free  to send me
a note.  I've added a few contributions, have a  few more  to sift through,
and still welcome more explanations to possible points of confusion in TNG.

===========================================================================
				  INDEX
===========================================================================
 1. TOS: The Guardian of Forever          ("City on the Edge of Forever")
 2. TOS: The slingshot effect             ("Tomorrow Is Yesterday")
 3. TOS: Cold-starting the warp engines   ("The Naked Time")
 4. TOS: Mr. Atoz's time travel system    ("All Our Yesterdays")
 5. TOS: Isis' time-space transporter     ("Assignment: Earth")
 6. TNG: Time hiccup                      ("We'll Always Have Paris")
 7. TNG: Picard from the future           ("Time Squared")
 8. TNG: Enterprise from the past         ("Yesterday's Enterprise")
 9. TNG: Riker thinks he's in the future  ("Future Imperfect")
10. TNG: Aliens from the future           ("Captain's Holiday")
11. TNG: Visiter from the past            ("A Matter of Time")
12. TNG: Time loop                        ("Cause and Effect")
13. TNG: Data in the past                 ("Time's Arrow")
14. TAS:                                  ("Yesteryear")
15. NOV:                                  ("Killing Time")
16. NOV:                                  ("Ishmael")
17. NOV:                                  ("Entropy Effect")
18. NOV:                                  ("Home Is The Hunter")
19. MOV: BoP goes to 1980s for whales     ("ST4: The Voyage Home")

---------------------------------------------------------------------------
1. THE GUARDIAN OF FOREVER IN TOS: CITY ON THE EDGE OF FOREVER

Why did everyone disappear when McCoy went back in time?   Because he saved
Edith Keeler from being his by a vehicle.

---------------------------------------------------------------------------
2. THE SLINGSHOT EFFECT IN TOS: TOMORROW IS YESTERDAY

---------------------------------------------------------------------------
3. COLD STARTING THE WARP ENGINES IN TOS: THE NAKED TIME

---------------------------------------------------------------------------
4. MR. ATOZ'S TIME TRAVEL SYSTEM IN TOS: ALL OUR YESTERDAYS

---------------------------------------------------------------------------
5. ISIS' TIME-SPACE TRANSPORTER IN TOS: ASSIGNMENT: EARTH

---------------------------------------------------------------------------
6. THE TIME HICCUP IN TNG: WE'LL ALWAYS HAVE PARIS

Why were there multiple copies of Data in this episode?

Why was one of the copies more accurate than the others?

---------------------------------------------------------------------------
7. PICARD FROM THE FUTURE IN TNG: TIME SQUARED

Why were there two Picards in this episode?

---------------------------------------------------------------------------
8. TASHA YAR AND TNG: YESTERDAY'S ENTERPRISE

FIRST TRY AT AN EXPLANATION (ottoh@cfsmo.honeywell.com):

A lot of people  seem to  be having  trouble understanding  the time travel
involved in  this  episode  (and  cluttering  up  the net  every few months
because of this).  I'm not the  best at  explaining these  sorts of things,
and if anyone else can in less space, feel free to email me.

Anyway...  in "YE" they start out in  the "peaceful"  timeline indicated by
the top line in the diagram below  (A)-->(B)-->(C).   When the Enterprise-C
broke through the barrier, it changed history as we know it  (from the time
of the battle onward) to a more hostile one (in  which the  Klingons are at
war with the Fed and Tasha didn't die at the "hands"  of Armus  (b)).  When
they sent the Ent-C  back through  the rift,  it fixed  whatever went wrong
with the Klingons/Federation, and restored the timeline to the  one we know
(including Yar being dead at the  hands of  the slime  beast in  a Glad Bag
(B)).  So no, Yar isn't still alive these  days.   And also  no, Yar didn't
"never exist and thus couldn't have  died due  to Armus".   *Everything* we
know about the time before "YE" happened exactly as we  saw because sending
the alternate-Yar back repaired all the damage to time.  The only change is
that somewhere  between  (A) and  (B), the  alternate Tasha  had a daughter
Sela, and was apparently killed trying to escape.

The line  from (c)--->(A)  represents the  Enterprise-C being  sent back in
time through the rift.

(A) is the time of the Ent-C's battle with the Romulans
(B) and (b) is the time around "Skin of Evil"
(C) and (c) is the time around "Yesterday's Enterprise"
(D) is the later seasons of TNG


                        Armus kills Tasha
             ----------------> (B) ----------------> (C) ---------> (D)
            /
           /
          /
Ent-C   (A) <--------------------------------------
battle    \                                        \
           \                                        \
            \                                        \
             ----------------> (b) ----------------> (c)
                          Armus doesn't
                           kill Tasha 

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

SECOND TRY AT AN EXPLANATION (stolen from someone else):

There is  one real  timeline -  the one  where Tasha  gets killed  by a mud
monster AND where an alternative time-line Tasha has a daughter called Sela
(apparently - I haven't  seen Redemption  but I  think I've  got the idea).
The only alternative time-line (well, as far as Tasha is  concerned) is the
alternative one we see in Yesterday's Enterprise.

Time for an ASCII-diagram! :

Real timeline :
---------------

  Alt Tashsa gets                 
  sent back through  Alt Tasha  Real Tasha   Alt Tasha  Real Tasha   Sela 
  wormhole into the  gives birth   born      dies (old   killed     turns up
  real timeline.     to Sela.        |        age?)          |         |
       |                 |           |            |          |         |
       V                 V           V            V          V         V
 ...-----------------------------------~~--------------------------------...
        <-------- Alt Tasha lives -----~~---------> 
                         <-------------~~------- Sela lives -------------...
        ^                            <-~~- Real Tasha lives ->
        |
        |
        +-------<---------------<-----------------<--------------+    
                                                                 |
                                                                 ^
Alternative timeline :                                           | 
----------------------
                                                             Alt Tasha 
                                 Alt Tasha                   decides to go   
                                   born                      through
                                     |                       wormhole
                                     |                           | 
                                     V                           V
  ...----------------------------------~~--------------------------------...
                                     <-~~- Alt Tasha lives ------>


Yes, there are two Tashas alive at the same time, living seperate lives but
this doesn't mean that they are  constantly mucking  up history.   They are
simply two seperate people - maybe they have the same DNA  structure but so
what - you can think of them as clones  if you  like.   History wasn't even
changed - history has always been like  this.   During the  first season we
saw the real Tasha walking about, but the  Alternative Tasha  was around as
well, we just didn't see her.

Just to clarify this point let's look at  the Enterprise-C's  history.  The
E-C starts off in the real timeline, gets transported  through the wormhole
into the alternative timeline.  Then the events  off Yesterday's Enterprise
occur and the alternative Tasha decides to go back  through.   The E-C then
returns to the real timeline and gets captured by the Romulans.

Theproblem is what was the wormhole that the 'real' timeline crew saw right
at the beginning of Yesterday's Enterprise?  According to  my chart nothing
special happens at all at that point in the real timeline.

My theory is that the wormhole just happened to occur  at the  same time in
the real timeline as it did in the alterantive one.   The  real Guinan then
somehow projected her  conciousness through  the wormhole  (not on purpose)
and into  the alternative  Guinan, making  her believe  that everything was
wrong.  This just happened to be at the same time as the E-C came through.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

THIRD TRY AT AN EXPLANATION (batemanc@p4.cs.man.ac.uk):

AMA, There are Three timelines involved,  not two.   The  first timeline is
the Trek timeline prior to YE ( NORM ).  In this timeline, the Enterprise-C
is destroyed  and  everything   proceeds  normally.     However,  something
interacts with a superstring to create a temporal rift.   This rift extends
back to the events of the Enterprise-C battling  the Romulans  and in doing
so creates  a  new  timeline:    Alternate  time line  1 (  A1 ).   In this
timeline, the high energy interaction with superstring material ( quoth the
Raven...  ) throws the Enterprise-C into the (  subjective )  present and -
BANG!  New timeline.  Alternate time line 2 ( A2 ).  This timeline has been
caused by no- Ent-C in the past and is  the Militaristic  timeline from YE.
In this timeline, the Ent-C  is sent  back to  A1 -  but with  Tasha Yar on
board.  This is the timeline which all episodes from YE onwards  are set in
( allowing  us  to  explain  a  number  of  Trek  inconsistancies  with the
Butterfly effect,  provided the  insonsistancies occur  in pre  and post YE
episodes ).

Now for the important  bit.   There is  only ONE  timeline 'active'  ( as I
believe this is how Star Trek time is intended to  function ).   The reason
for this is:  The wormhole in NORM creates A1 and then destroys A1 and NORM
to create A2.  A2 then recreates A1 and destroys A2 ( the  shrewd among you
may point out that there are hence two different  A2's, but  to all intents
and purposes they are equivalent ).  Guinan's senses extend across time and
space and hence she can realise that the A2 timeline  is `wrong'  ( in that
there was a timeline in which no such war  occured ).   Sela  appears in A2
only.

---------------------------------------------------------------------------
9. RIKER THINKS HE'S IN THE FUTURE IN TNG: FUTURE IMPERFECT

---------------------------------------------------------------------------
10. THE ALIENS FROM THE FUTURE IN TNG: CAPTAIN'S HOLIDAY

---------------------------------------------------------------------------
11. THE VISITOR FROM THE PAST IN TNG: A MATTER OF TIME

---------------------------------------------------------------------------
12. THE TIME LOOP IN TNG: CAUSE AND EFFECT

Wasn't The Boseman ship in the loop  for several  decades?   Why don't they
have a *really* bad feeling of deja vu?

No, the general  consensus is  that the  ship shot  forward in  time to the
point that the START of the Enterprise's loop began.

---------------------------------------------------------------------------
13. DATA IN THE PAST IN TNG: TIME'S ARROW

How can Data work on his the head they found from  San Fransisco?   How can
there be two copies of his head?

Thanks to Barry Geipel (barry@godzilla.quotron.com) for this next part:

The away team meets up with Data and Guinun in  1893.   They determine that
they are trapped and have no way  to get  back to  the 24th  century.  They
place key information in Data's head and place it in the cavern.   The Away
team also tells Guinun some information on how to get at the information so
that the Enterprise can extract it.  (As a possibile twist,  they also have
Mark Twain write a classic story (_Mysterious Stranger_ perhaps?)  in which
more information can be extracted).  Also, during this time, Picard somehow
saves Guinun's life (or tells her about the Borg) making  it essential that
Picard goes back into time.

Sometime after the Away  team goes  down to  the planet,  Guinun tells Worf
about her historical encounter  with Picard  and the  Away team.   With the
help of the Mark Twain novel, the phase thingamajig in Data's  head and any
information in Data's head, Worf  and the  Enterprise crew  rescue the Away
team.

Since Data must leave his head  behind, Data  is brought  back headless and
the 600 year old head is re-attached.

                                                        
            /-------- Enterprise rescues Data @ Away Team-----\        
           /                                                   \       
           v                                                   v       
 --A--B-C--D---------- Main-line History ---------E---------F--G----->
   ^                                                        /          
   \                                                       /           
    \------- Data @ Away team go back in time-------------/            


	A - 1893
		Guinun meets Picard for the first time
		Picard meets Guinun for the second time
	B - Some time after Data @ Away team go back to 1893
		Picard Saves Guinun's life ( or tells here about the
		Borg or something....
	C - 1893
		Away team places information of how to rescue them into
	    	Data's head ( as well as the phase thingimijig ), removes
	    	Data's head and places it in the cavern. Away team tells
	    	Guinun how to extract the info so that she can tell the
		Enterprise crew how to go back to rescue them. Also,
		Mark Twain puts key information into a "classic" as
		further reference ( _Mysterious Stranger_ ???)

	D - 1893
		Data (minus head) and away team is rescued

	E - Sometime earlier in the 24th century
		Guinun meets Picard for the second time
		Picard meets Guinun for the first time

	F - 24th Century
		Data @ Away team go back to 1893

	G - 24th Century
		Enterprise recues Data (minus head) and Away team.
		Data and 600 year old head are reattached. 

Possible plot holes:

	Q - Why didn't Data get the info when he first found his head?
	A - He had not yet figured out how to put the information in!
	    (Perhaps that is what his "invention" in 1893 is for)

---------------------------------------------------------------------------
14. TAS: YESTERYEAR

---------------------------------------------------------------------------
15. NOV: KILLING TIME

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16. NOV: ISHMAEL

---------------------------------------------------------------------------
17. NOV: ENTROPY EFFECT

---------------------------------------------------------------------------
18. NOV: HOME IS THE HUNTER

---------------------------------------------------------------------------
19. THE BIRD OF PREY GOES TO THE 1980S FOR WHALES IN ST4: THE VOYAGE HOME

Why didn't the space-time continuum get screwed  up with  Scotty giving the
man from the past the formula for transparent aluminum?

Just how old are Kirk's glasses?  Isn't this an infinite loop?

===========================================================================

Again, if you  know of  any other  topics that  should be  included in this
list, feel  free to  email me  at one  of the  addresses below.   Thanks to
everyone who contributed to this article.

		--Otto "HACK-MAN" Heuer
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