# Time travel paradox...can this happen?



## Rashaad Bell (Oct 7, 2011)

Through time travel, can a person give birth to themselves?

Example: Tom and Mary find a baby on their doorstep. They name the baby Anne. Anne grows up, is now twenty years old and becomes pregnant. Just before birth, Anne is thrown back in time twenty years. Anne has the baby, seeks out Tom and Mary and leaves the baby on the doorstep. Tom and Mary find a baby on their doorstep. They name the baby Anne.

I think that's possible. Person I'm arguing with says you can't give birth to yourself. What do you think?


----------



## Guest (Nov 30, 2012)

Gut feeling says this shouldn't be possible but in your fiction, who knows?


----------



## 56139 (Jan 21, 2012)

Wow - that's weird.  If this is science fiction, you probably won't get away with it unless you have a valid mechanism - I can't think of one off-hand, but I'm sure if you looked into it you'd find a way to explain it.  

But if it's speculative or something softer, you wouldn't need many details.  If you do it right.


----------



## Charmaine (Jul 20, 2012)

Wow my friends and I were talking about this TODAY
What are the chances?
Anyway. We all decided that time travel paradoxes are possible, because by creating one the individual creates an alternate reality that the person will then exist.
So Anne will be then placed into a reality separate then where she would've ended up in had she not left herself on the doorstep.
We compared time paradoxes to spinning wheels were after one choice is taken options are crossed off, but still others are available.


----------



## JRLeckman (Dec 22, 2010)

Rashaad Bell said:


> Through time travel, can a person give birth to themselves?
> 
> Example: Tom and Mary find a baby on their doorstep. They name the baby Anne. Anne grows up, is now twenty years old and becomes pregnant. Just before birth, Anne is thrown back in time twenty years. Anne has the baby, seeks out Tom and Mary and leaves the baby on the doorstep. Tom and Mary find a baby on their doorstep. They name the baby Anne.
> 
> I think that's possible. Person I'm arguing with says you can't give birth to yourself. What do you think?


I would like to point out that Anne's father would also be her own lover. Just saying.


----------



## Nathan Elliott (May 29, 2012)

Just thinking of biology, this should be impossible because a child inherits only 1/2 of its genes from its mother.  If a woman were to give birth to herself, the baby would need to have 100% of the mother's genes.  Unless there is some other sci-fi involved (cloning an embryo from a single parent?), it would be inconsistent, I think.


----------



## JRLeckman (Dec 22, 2010)

Nathan Elliott said:


> Just thinking of biology, this should be impossible because a child inherits only 1/2 of its genes from its mother. If a woman were to give birth to herself, the baby would need to have 100% of the mother's genes. Unless there is some other sci-fi involved (cloning an embryo from a single parent?), it would be inconsistent, I think.


This is actually a really good point. For Anne to give birth to herself, we would have to assume that baby Anne received no genetic variation from the father. Any child will have to be slightly different. Now, if Anne cloned herself, carried the baby to term, then dropped herself off in the past to grow up and become her, that would be extremely interesting. However, her existence would be predicated on existing on the "first" go through of the time sequence. Depending on which version of time you utilize, this would have to be the immutable form of time, the kind where you can't actually change the past because everything has already happened. In this form, you could have such a scenario, but not including a father.


----------



## 56139 (Jan 21, 2012)

Nathan Elliott said:


> Just thinking of biology, this should be impossible because a child inherits only 1/2 of its genes from its mother. If a woman were to give birth to herself, the baby would need to have 100% of the mother's genes. Unless there is some other sci-fi involved (cloning an embryo from a single parent?), it would be inconsistent, I think.


There are more ways than one to get a genome together!


----------



## ZacharyBonelli (Jun 29, 2012)

Nathan Elliott said:


> Just thinking of biology, this should be impossible because a child inherits only 1/2 of its genes from its mother. If a woman were to give birth to herself, the baby would need to have 100% of the mother's genes. Unless there is some other sci-fi involved (cloning an embryo from a single parent?), it would be inconsistent, I think.


Anne's baby would be half her own DNA, and half that of the father. If all the Annes occupy the same universe, then the each "iteration" of Anne in the loop, if she sleeps with the same guy, all would have the same genetic material over again -- 50% of dad's DNA is the same as 50% of mom's. I'm not sure, but I think there'd be so much possibility for duplication, that Anne would be at risk for severe psychological and physical defects.

The only way for this to work at all is if, as mentioned above, each time shift causes Anne to shift to alternate quantum universe, in which case there is no logical paradox because each iteration is self-contained in its own causality chain, and baby Anne by definition always has a "new" father with completely different DNA from her own.

In my novel, the metaxia abhors a temporal paradox the same way that space abhors a vacuum, and it will crush out of existence any universes with a contorted time-space continuum, like the one described here. That's exactly the kind of thing that will p*ss off Mythos and Ethos.


----------



## Terrence OBrien (Oct 21, 2010)

Let's assume the Annes are all identical. Just for fun. Somehow the biology works.

I think the Annes would be multiplying. One new Anne every twenty years. In year 80, there are five Annes. One is newborn. Then there are Annes aged 20,40,60, and 80. It's a sequence of mother/daughter.

Only the pregnant Annes are thrown back in time. Once thrown back, the 20-year-old Annes leave the baby on the porch continue to live on.

A forty-year-old Anne could sit there and watch her pregnant 20-year-old daughter get thrown back in time.

So we would have five separate individuals.


----------



## PaulLev (Nov 2, 2012)

Check out Robert Heinlein's "All You Zombies-" - short story, 19 pages - in which the time traveler is (convincingly) his/her own mother and father.


----------



## Nathan Elliott (May 29, 2012)

ZacharyBonelli said:


> ... then the each "iteration" of Anne in the loop, if she sleeps with the same guy, all would have the same genetic material over again -- ...


If I understand what you are saying, then I disagree. By definition, baby Anne has 100% of adult Anne's DNA or else she is not the same person as her child. If, as you say, her child got 50%-50% from Anne and her lover/father then each iterant would be a genetically distinct individual, not another Anne. In that case, each time around the original Anne's genetic contribution gets cut in half. I think eventually the child would converge to being genetically based entirely on the father--but with all sorts of recessive traits due to sometimes getting two of the same gene (AA or BB) whereas the father had AB.


----------



## Rashaad Bell (Oct 7, 2011)

Terrence OBrien said:


> Let's assume the Annes are all identical. Just for fun. Somehow the biology works.
> 
> I think the Annes would be multiplying. One new Anne every twenty years. In year 80, there are five Annes. One is newborn. Then there are Annes aged 20,40,60, and 80. It's a sequence of mother/daughter.
> 
> ...


This is what I figured. I wanted the now older Anne who had gone back in time, had the baby, then grew to be old be the one that causes twenty year old Anne to travel in the past. Old Anne knows that in order for her to keep the current timeline, then young Anne needs to go back in time, hence old Anne triggers the time travel event in the future. Does that make any sense?

Of course, that places the "Anne's" themselves in a time loop.

Yes the boyfriend would still be the father.


----------



## Rashaad Bell (Oct 7, 2011)

Nathan Elliott said:


> If I understand what you are saying, then I disagree. By definition, baby Anne has 100% of adult Anne's DNA or else she is not the same person as her child. If, as you say, her child got 50%-50% from Anne and her lover/father then each iterant would be a genetically distinct individual, not another Anne. In that case, each time around the original Anne's genetic contribution gets cut in half. I think eventually the child would converge to being genetically based entirely on the father--but with all sorts of recessive traits due to sometimes getting two of the same gene (AA or BB) whereas the father had AB.


You mean kinda like that clone movie with Micheal Keaton where each clone of himself gets dumber and dumber?


----------



## Terrence OBrien (Oct 21, 2010)

> Of course, that places the "Anne's" themselves in a time loop.


Yes. Every Anne would have to have an infinite number of Anne ancestors. If not, then some random Judy left Anne-1 on the doorstep. When pregnant Anne-1 goes back in time, she meets Judy leaving Anne-1 on the doorstep. Anne-1 then adds Anne-2 to the doorstep.

We also can make a case that the doorstep is surrounded by thousands of Annes with babies. If the loop is countable, then Anne-1 was on the step leaving Anne-2. Then Anne-2 is thrown back at age twenty. Who does she see but Anne-1 with a baby Anne-2.....

You may have to make a rule so the Annes don't take over the universe.


----------



## dalya (Jul 26, 2011)

Time travel isn't real.

Neither is fiction.

Do what you want! Haters gonna hate.


----------



## Nathan Elliott (May 29, 2012)

Rashaad Bell said:


> You mean kinda like that clone movie with Micheal Keaton where each clone of himself gets dumber and dumber?


Maybe. But I would say more like inbreeding than imperfect cloning. The clones all looked like Keaton with minor differences, but these Annes would each look radically different. Actually, at some point, a new Anne would probably turn out to be male and then the cycle would be hard to continue.


----------



## telracs (Jul 12, 2009)

there's actually a line in one of Spider Robinson's short stories spoken by a time traveler along the lines of "i don't know when i'll be back, i have to go spend some time with dad.  i think i might be mom".

he never explains if she is her own mom, or exactly how the biology would work, but your post made me think of it....

now, my problem with time loops is how did the loop start?  in your case, where did the first Ann come from?  where do her maternal genes come from?


----------



## Rashaad Bell (Oct 7, 2011)

telracs said:


> there's actually a line in one of Spider Robinson's short stories spoken by a time traveler along the lines of "i don't know when i'll be back, i have to go spend some time with dad. i think i might be mom".
> 
> he never explains if she is her own mom, or exactly how the biology would work, but your post made me think of it....
> 
> now, my problem with time loops is how did the loop start? in your case, where did the first Ann come from? where do her maternal genes come from?


That's a cool line that time traveler said.

Hmm...I guess technically, if she gave birth to herself, there is no beginning or end? Like which came first, the chicken or the egg type situation. Idk though.


----------



## Rashaad Bell (Oct 7, 2011)

Terrence OBrien said:


> Yes. Every Anne would have to have an infinite number of Anne ancestors. If not, then some random Judy left Anne-1 on the doorstep. When pregnant Anne-1 goes back in time, she meets Judy leaving Anne-1 on the doorstep. Anne-1 then adds Anne-2 to the doorstep.
> 
> We also can make a case that the doorstep is surrounded by thousands of Annes with babies. If the loop is countable, then Anne-1 was on the step leaving Anne-2. Then Anne-2 is thrown back at age twenty. Who does she see but Anne-1 with a baby Anne-2.....
> 
> You may have to make a rule so the Annes don't take over the universe.


I never thought of it that way. Each "birth" in the past would have to create its own timeline.


----------



## dotx (Nov 4, 2010)

Dalya said:


> Time travel isn't real.


Are you sure?


----------



## SS_Muller (Jan 14, 2012)

This reminds me of a Futurama episode where Fry, the protagonist, finds out he's his own grandfather. (Roswell That Ends Well)

Apparently this phenomenon is called "Bootstrap paradox" http://en.wikipedia.org/wiki/Ontological_paradox



> *A man travels back in time and falls in love with and marries a woman, who he later learns was his own mother, who then gives birth to him. He is therefore his own father and, because of this, also his own grandfather, great-grandfather, great-great grandfather, great-great-great grandfather and so on, making his ancestry infinite, and also giving him no origin for his paternal genetic material.*


----------



## John Daulton (Feb 28, 2012)

Yeah, the big mystery here is that the parents FIND Anne. So HALF of the equation is missing.

For Anne to give birth to herself, the adoptive parents you name don't matter and actually serve as a distraction.

What matters is Anne and her mate. So, the child, Anne, needs to grow up, go back in time, meet a man who impregnates her.

That's your paradox. She has to exist before she can mate. You start your scenario off with her being born, but you don't have a father. You name two random people who don't matter to raise her. Anyone can raise her.
You need to start your story with "Dude X bangs Anne. She has a baby." From that, SHE (Anne) hands off the baby (who is NOT its own mother, given that Anne exists and the baby exists, so obviously they are not one person) to Tom and Mary. That child, Anne2, will go back into time and meet Dude X. He bangs her and they have a baby. It's not the same baby.

Here's an easier way to see it:

Green was born when Yellow and Blue mated.

So, Yellow and Blue meet, and make Green (Anne). Green gets raised by Brown and Gray. Then Green goes back in time and meets Blue. They can't make Yellow. Nor can they make Green. Or at least not the same Green.


----------



## Rashaad Bell (Oct 7, 2011)

John Daulton said:


> Yeah, the big mystery here is that the parents FIND Anne. So HALF of the equation is missing.
> 
> For Anne to give birth to herself, the adoptive parents you name don't matter and actually serve as a distraction.
> 
> ...


I think ss_muller is on to something.

The bootstrap paradox is a paradox of time travel in which information or objects can exist without having been created. After information or an object is sent back in time, it is recovered in the present and becomes the very object/information that was initially brought back in time in the first place.

Anne's "baby" would be the object sent back in time in this case. She gets pregnant in the future. Goes back in time and has the baby. Gives the baby to the adoptive parents in the past. The baby grows up and gets pregnant. Goes back into the past. Gives the baby to the adoptive parents in the past, ect, ect...

The adoptive parents are important, because they become the constant throughout every instance of time travel. The always raise a baby dropped on their door step. Anne always goes in the past and puts her baby on their doorstep. They always name the baby Anne. The adoptive parents being a part of the process is what lets you know that Anne and her baby are one in the same, since Anne is the only person giving them a baby.

Um...that makes sense. Right? Lol


----------



## psychotick (Jan 26, 2012)

Hi,

That's an inspired variant of the bootstrap paradox, but no. By the laws of genetics this paradox shall not pass! Even if Anne grows up meets the same guy gets pregnant by him, the offspring would still be a different baby. Men give millions of sperm each time they ejaculate. What would be the odds that when Anne and Mr. X got together the same sperm combined with the same egg? Bugger all. So each iteration of the process there's be a different baby, essentially a brother or a sister to Anne.

Having said that cloning might be an alternative.

Cheers, Greg.


----------



## CEMartin2 (May 26, 2012)

There's a Fred Ward movie called "Time Rider" where he becomes his own grandfather... can't think of an own dad/mom example.


----------



## Hugh Howey (Feb 11, 2012)

When does Anne change her name to Mary?


----------



## Debbie Bennett (Mar 25, 2011)

Heinlein's Door Into Summer remains the best book that deals with time travel for me.



And the Terminator films were the only plotlines that didn't tie themselves up in paradoxes (or if they did, they were subtle enough for me not to notice and I'm a real nerd for pointing out plot-holes when watching films or tv)


----------



## KM Logan (Jun 2, 2012)

All I can think when I read this thread is "What do we want? Time Travel! When do we want it? It's Irrelevant!"

But other than that this is making my head spin.


----------



## ZacharyBonelli (Jun 29, 2012)

Nathan Elliott said:


> If I understand what you are saying, then I disagree. By definition, baby Anne has 100% of adult Anne's DNA or else she is not the same person as her child. If, as you say, her child got 50%-50% from Anne and her lover/father then each iterant would be a genetically distinct individual, not another Anne. In that case, each time around the original Anne's genetic contribution gets cut in half. I think eventually the child would converge to being genetically based entirely on the father--but with all sorts of recessive traits due to sometimes getting two of the same gene (AA or BB) whereas the father had AB.


Rethinking this, I think you're right. And too much of the same genetic material would mean that Anne would come unappealing to her father really quick in subsequent iterations, if he is indeed the same person. I do stand by my original assertion that time jumps also cause quantum shifts. Or you could just have paradoxical universes be obliterated and never have existed. Just sayin'.


----------



## Hugh Howey (Feb 11, 2012)

KM Logan said:


> All I can think when I read this thread is "What do we want? Time Travel! When do we want it? It's Irrelevant!"


Where is this from? I want to steal and share this.


----------



## KM Logan (Jun 2, 2012)

Hugh Howey said:


> Where is this from? I want to steal and share this.


I saw it on pintrest.


----------



## QuantumIguana (Dec 29, 2010)

Sometimes it seems that the only reason people do time travel is to do "Do the nasty in the pasty", as Philip J. Fry would say.  

The only way that I could see someone giving birth to themselves is with in vitro vertilization. The embryo is produces, and the adult that embryo will llater become travels to the past, and the embryo is implanted in her. She gives birth to herself.


----------



## KM Logan (Jun 2, 2012)

Would it be possible to give birth to an ancestor?


----------



## vrabinec (May 19, 2011)

She'd have to have a mother in the first place in order to be born to go back that first time and get pregnant, so unless your future happens before the initial present, she'd never be born. But, this gives me pause, because maybe I actually CAn do what people have been telling me for years, go fuck myself.


----------



## ♨ (Jan 9, 2012)

Nathan Elliott said:


> Just thinking of biology, this should be impossible because a child inherits only 1/2 of its genes from its mother. If a woman were to give birth to herself, the baby would need to have 100% of the mother's genes.


The baby would need to be 100% identical to the mother's genome. That doesn't necessarily mean the baby has to get 100% of the mother's genes.

Let's say the mother is AA-BB-AB-BA.

The father is CB-CC-AB-BA.

The baby's genes are half the father and half the mother. So, the baby could be numerous variations, one of which would be AA-BB-AB-BA because the AA-BB could come from the mother and AB-BA from the father.

Of course, the human genome has more pairs than that, but the point is that if 50% of the father's genes transferred to the baby match the 50% of the mother's genes not transferred to the baby, then the baby could be 100% identical to the mother.

So, while improbable, it's not impossible that someone could be their own parent.


----------



## Nathan Elliott (May 29, 2012)

Dan C. Rinnert said:


> The baby would need to be 100% identical to the mother's genome. That doesn't necessarily mean the baby has to get 100% of the mother's genes.
> 
> Let's say the mother is AA-BB-AB-BA.
> 
> ...


Good point. It is so astronomically improbable that we'd call it impossible in normal science, but in a time travel book, why not? If everything happens the same way each time through the loop, then that improbable gene pair-up could repeat as well. Of course the odds of it happening even one time are.... You'd almost need a bored omnipotent being setting it up intentionally to be believable, IMHO.


----------



## JRTomlin (Jan 18, 2011)

Rashaad Bell said:


> This is what I figured. I wanted the now older Anne who had gone back in time, had the baby, then grew to be old be the one that causes twenty year old Anne to travel in the past. Old Anne knows that in order for her to keep the current timeline, then young Anne needs to go back in time, hence old Anne triggers the time travel event in the future. Does that make any sense?
> 
> Of course, that places the "Anne's" themselves in a time loop.
> 
> Yes the boyfriend would still be the father.


You might want to be aware that you are treading on extremely sensitive territory with incest. There are retailers who won't sell it and reviewers who will have a very strong negative reaction. That doesn't mean you can't write it. I wouldn't, but that's me.


----------



## swolf (Jun 21, 2010)

Wouldn't there be another baby (Baby Annie) on the doorstep when Anne arrived to put her baby there?

Then the couple would have two babies to raise (basically, a mother and her daughter).  Then let's say the daugher grows up, gets pregnant, then goes back in time.  She would go back into her past, where she was one of two babies on the doorstep.  So now she would be adding a third. 

So now the couple would find three babies on their doorstep (a grandmother, a mother, and a daughter (with the mother and daughter both fathered by the same man.))

And so on, making my head hurt to think about it.


----------



## swolf (Jun 21, 2010)

vrabinec said:


> She'd have to have a mother in the first place in order to be born to go back that first time and get pregnant, so unless your future happens before the initial present, she'd never be born. But, this gives me pause, because maybe I actually CAn do what people have been telling me for years, go [expletive] myself.


There's a book titled The Man Who Folded Himself, by David Gerrold, about a time traveler who has sex with himself. Even has group orgies with himself. Eventually the timeline gets screwed up and female versions of himself begin to appear, and then it's really on, with offspring and everything.

Really messed up. Of all the things I would want to do with a time travel machine, having sex with myself is WAY down on the list. WAY, WAY down.


----------



## swolf (Jun 21, 2010)

JRTomlin said:


> You might want to be aware that you are treading on extremely sensitive territory with incest. There are retailers who won't sell it and reviewers who will have a very strong negative reaction. That doesn't mean you can't write it. I wouldn't, but that's me.


I think that if you don't deal with it in a lacivious manner, you'll be fine. After all, wasn't that the secret in the movie Chinatown?


----------



## ♨ (Jan 9, 2012)

swolf said:


> Wouldn't there be another baby (Baby Annie) on the doorstep when Anne arrived to put her baby there?


No, because the baby isn't there until Anne puts the baby there.


----------



## swolf (Jun 21, 2010)

Dan C. Rinnert said:


> No, because the baby isn't there until Anne puts the baby there.


In Anne's past, she was found on the doorstep. So when she goes into her past, she'll be on the doorstep as a baby. Placing her own baby there will place a second baby on the doorstep.


----------



## telracs (Jul 12, 2009)

KM Logan said:


> Would it be possible to give birth to an ancestor?


this i'm willing to grant as possible.

but again, my concern is how things get started.

now, that's just me. i look for these things. but not everybody will look for/at the same details.

so, in the end, write what you want to write and realize that some people will ignore any missing details, some people will roast you for them, and some people will start writing their own version of things.


----------



## Becca Mills (Apr 27, 2012)

A different take on Dalya's point: once you get into time travel, you can mess with quantum mechanics, and all sorts of things that don't make sense on the macro level make sense happen  in that context. Spin the Anne situation as a "quantum paradox."


----------



## B. Justin Shier (Apr 1, 2011)

Rashaad Bell said:


> Through time travel, can a person give birth to themselves?
> 
> Example: Tom and Mary find a baby on their doorstep. They name the baby Anne. Anne grows up, is now twenty years old and becomes pregnant. Just before birth, Anne is thrown back in time twenty years. Anne has the baby, seeks out Tom and Mary and leaves the baby on the doorstep. Tom and Mary find a baby on their doorstep. They name the baby Anne.
> 
> I think that's possible. Person I'm arguing with says you can't give birth to yourself. What do you think?


I believe this process is referred to as backcrossing (sans time travel). The technique involves repetitively crossing generation after generation of hyrbid progeny with a recurrent parent. I've actually used some inbred backcrossed lines (IBLs) that had specific genes made non-functional. Never bred them myself, though. That would be gross. 










"The contribution of the donor parent genome is reduced by half with each generation of backcrossing. Percentages of recurrent parent (light purple) are expressed as a ratio to percentages of donor parent (dark red-purple)." - http://pbgworks.org/node/642

B.


----------



## ♨ (Jan 9, 2012)

swolf said:


> In Anne's past, she was found on the doorstep. So when she goes into her past, she'll be on the doorstep as a baby. Placing her own baby there will place a second baby on the doorstep.


She won't find herself on the doorstep as a baby because she hasn't put herself there yet.


----------



## B. Justin Shier (Apr 1, 2011)

Dan C. Rinnert said:


> She won't find herself on the doorstep as a baby because she hasn't put herself there yet.


That would be based on the time line protection hypothesis...I think.

You can get around this by employing the branching universe hypothesis...I think.

BTW, the wiki article on this is fabulous. https://en.wikipedia.org/wiki/Temporal_paradox


----------



## swolf (Jun 21, 2010)

Dan C. Rinnert said:


> She won't find herself on the doorstep as a baby because she hasn't put herself there yet.


Here is how the OP explained it:



Rashaad Bell said:


> Example: Tom and Mary find a baby on their doorstep. They name the baby Anne. Anne grows up, is now twenty years old and becomes pregnant. Just before birth, Anne is thrown back in time twenty years. Anne has the baby, seeks out Tom and Mary and leaves the baby on the doorstep. Tom and Mary find a baby on their doorstep. They name the baby Anne.


In that scenario, Anne has a past, and in that past she was left on a doorstep. If she travels to her past, she will see herself on the doorstep.

This all gets back to the question of how it began, which is, essentially, the paradox. Who left Anne on the doorstep the first time?


----------



## BrianKittrell (Jan 8, 2011)

I think my head just exploded.

So, you have Tom and Mary and the finding of the baby, Anne. Anne goes back in time and leaves the baby on their doorstep. Now, this would only be possible if someone else left Anne on the doorstep. Perhaps the people who left Anne see another baby on the doorstep and decide to bring Anne to another doorstep? That would dramatically alter the future. Or, what if Anne left her baby after the Anne was left on the doorstep in the past? She would come back to the future with a sibling that she's never met? Would she be time synched in the future to know about the new sibling and thus know that the sibling was actually her own child?

Not an easy task of explaining all of that. I pity you... and envy you at the same time.


----------



## MegSilver (Feb 26, 2012)

Am in a hurry; forgive me for skipping -- and possibly repeating -- what's been said before:

What if giving birth to herself is the ONLY way to get her into an alternate reality where she otherwise wouldn't be?


----------



## ♨ (Jan 9, 2012)

swolf said:


> In that scenario, Anne has a past, and in that past she was left on a doorstep. If she travels to her past, she will see herself on the doorstep.


No, because she hasn't put herself there yet.



swolf said:


> This all gets back to the question of how it began, which is, essentially, the paradox. Who left Anne on the doorstep the first time?


Stop thinking linearly. Anne put herself there. The baby on the porch is Anne's past but it's also Anne's future and, when she takes the baby there, it's Anne's present. There's no first time; there's just the one time. And that one time is always the same time, whether it's Anne's past, present or future.


----------



## PaulLev (Nov 2, 2012)

Even without the genetic problem of being your own parent via time travel, there are paradoxes in every aspect of time travel - the grandfather paradox (you go back in time and kill your own grandfather, so how were you born?), the source of time travel paradox (your future self comes back in time and tells you how to build a time machine, and you use this knowledge to build it, so where did the knowledge come from in the first place?), etc.

These paradoxes make time travel utterly different from any other kind of science fiction. Traveling faster than light, for example, may go contrary to relativity theory, but it doesn't create paradoxes.

That's why, although time travel is enormously enjoyable to read and write, it likely is impossible. Which is precisely why it's so enjoyable to think about it. Or, if it is possible - say, by Wheeler's multi-world model, in which a new universe is created every nanosecond a time traveler acts or just exists in the past - it would be in a world insanely different from what we now suppose it to be.

Travel to the future creates the additional problem of negating free will. If I travel to tomorrow, and see you wearing a red shirt, you have no choice but to wear a red shirt tomorrow.

See http://paullevinson.blogspot.com/2006/11/enjoyable-trouble-with-time-travel.html for more.


----------



## ElisaBlaisdell (Jun 3, 2012)

PaulLev said:


> Check out Robert Heinlein's "All You Zombies-" - short story, 19 pages - in which the time traveler is (convincingly) his/her own mother and father.


I was going to post this too!


----------



## ♨ (Jan 9, 2012)

Perhaps paradoxes only appear to exist because we're three-dimensional beings trying to understand a fourth-dimensional world.

Sure, we can say we travel through time, just one way (into the future), but that's not really time travel, at least not travel in the way we consider it.  For example, if you drive from California to Maine, that's a trip.  That's travel.  But, we move further than that each day just by standing still, because of the Earth's rotation.  But, we don't typical consider that as travel in the same way as we view a cross-country drive.

So, the type of time "travel" we do is much the same.  We may be traveling through time technically, but it's not really travel in the way we generally define travel.  We can't pick and choose a destination.  We just have to wait until we get there, which happens whether or not we try to get there.

In that respect, we don't really experience the fourth dimension, which means those things some think of as paradoxes may not be paradoxes at all.

For example, try to explain height to a two-dimensional being.  They travel of their own accord in two dimensions.  They may be able to grasp the concept that there is a third-dimension, but they cannot experience it.  If, for example, they existed on a flat plane on a sheet of paper, how would you show them height?  If you put a water bottle on their plane, all they can experience is the part that intersects their plane.  To them, it will look like any other two-dimensional object.  Height would remain a concept they could theorize about, but not experience.

When that water bottle is removed from their plane, can they envision how it can still exist?  It's no longer intersecting their plane, so did it cease to exist?  And what if you lift it from one spot and place it on another?  Can they understand how it got from one place to the other without remaining connected to their plane of existence?  Can they understand that something need not have originated in their plane for it to exist within theirs?  If something appears at point A, does that mean it cannot have been created at point B?  And how does it get from point A to point B without a line from one point to another in their plane?

It's much the same for us.  We don't really experience the fourth-dimension, so it's difficult to grasp what it might be like.  Would what we may think of as paradoxes really be paradoxes?  Maybe not.


----------



## PaulLev (Nov 2, 2012)

Dan C. Rinnert said:


> So, the type of time "travel" we do is much the same. We may be traveling through time technically, but it's not really travel in the way we generally define travel. We can't pick and choose a destination. We just have to wait until we get there, which happens whether or not we try to get there.


Exactly. The way I would put this is that the "travel" in time travel is a misplaced metaphor - or, a misapplication of how we move through space to how we might move through time. That's why nothing in space travel - on or off planet - courts the kinds of paradox we encounter in time travel.


----------



## B. Justin Shier (Apr 1, 2011)

PaulLev said:


> Exactly. The way I would put this is that the "travel" in time travel is a misplaced metaphor - or, a misapplication of how we move through space to how we might move through time. That's why nothing in space travel - on or off planet - courts the kinds of paradox we encounter in time travel.


Well, there are things like the twin paradox and ladder paradox due to time dilation that still hurt my head. But I get your point. At least we have formulae that can make predictions about them.

B.


----------



## BrianKittrell (Jan 8, 2011)

I understand what you're trying to do, but this thread is evidence of how readers will react. If we're writing a story for ourselves, anything goes. Writing for other readers requires not making their heads hurt.


----------



## PaulLev (Nov 2, 2012)

B. Justin Shier said:


> Well, there are things like the twin paradox and ladder paradox due to time dilation that still hurt my head. But I get your point. At least we have formulae that can make predictions about them.
> 
> B.


Exactly.


----------



## swolf (Jun 21, 2010)

Dan C. Rinnert said:


> No, because she hasn't put herself there yet.
> 
> Stop thinking linearly. Anne put herself there. The baby on the porch is Anne's past but it's also Anne's future and, when she takes the baby there, it's Anne's present. There's no first time; there's just the one time. And that one time is always the same time, whether it's Anne's past, present or future.


Sure, if we 'stop thinking,' linearly or otherwise, then we won't encounter any paradoxes. Basically, what you're saying is, 'This doesn't break the rules if you forget about the rules.'

This same ignoring of logic could be applied to the Grandfather Paradox. If I go back in time and kill my grandfather, it doesn't matter that I will never be born, because I had to have been born in order to kill him.


----------



## vrabinec (May 19, 2011)

Dan C. Rinnert said:


> No, because she hasn't put herself there yet.
> 
> Stop thinking linearly. Anne put herself there. The baby on the porch is Anne's past but it's also Anne's future and, when she takes the baby there, it's Anne's present. There's no first time; there's just the one time. And that one time is always the same time, whether it's Anne's past, present or future.


The baby arriving would have to be spontaneous creation, and once Anne arrives, there are now two Annes, except they occupy the same space which is impossible according to the laws of physics, therefore, the cycle would HAVE to be ended with only one cycle. The baby and Anne pop out of nothing (which is theorhetically possible accoring to quantum physics), they do one loop, and then something changes so the loop is not repeated.


----------



## ♨ (Jan 9, 2012)

swolf said:


> Sure, if we 'stop thinking,' linearly or otherwise, then we won't encounter any paradoxes. Basically, what you're saying is, 'This doesn't break the rules if you forget about the rules.'


You're only breaking the rules of linear time. But, by nature, a time traveler exists in non-linear time.



vrabinec said:


> The baby arriving would have to be spontaneous creation, and once Anne arrives, there are now two Annes, except they occupy the same space which is impossible according to the laws of physics, therefore, the cycle would HAVE to be ended with only one cycle. The baby and Anne pop out of nothing (which is theorhetically possible accoring to quantum physics), they do one loop, and then something changes so the loop is not repeated.


There is no spontaneous creation. The loop can be created before the loop is called. Because the event involves time travel, the loop exists outside normal, linear time. Once the non-linear loop exists, it can exist at any point in linear time.


----------



## Ergodic Mage (Jan 23, 2012)

Yes there are two logical solutions where Anne can give birth to herself.

Many World Interpretation
This is where the Universe is very flexible at the quantum scales, you have a problem the universe splits a new spcetime line to resolve it. So when Anne comes back a new timeline is created where she can give birth to herself. This basically works because the "original" Anne is from a different timeline than the one of "birth" Anne.
This also resolves the DNA paradox mentioned previously because in one timeline there is only one set of DNA; the "original" Anne goes down a different one than the "birth" Anne.

Self-Consistency Principle for Closed Timelike Curves
General Relativity allows time travel along CTCs, but only such that the effect is self consistent. In CTCs there is only one timeline but multiple reference views (relativity in action). This means there is only one Anne but two vies of her: Anne Future and Anne Now.
The conception of Anne is the critical point where she is spontaneously created; note this is not a different Anne with different DNA, there is only one Anne. As long as Anne gives birth to herself, conceives herself and travels back in time, everything is Self-Consistent this single time loop can happen. If one of those does not happen then the probability if her traveling back in time is zero and it can not happen.

A note on the repeatability of the loop.
In MWI the time travel can be repeated by Anne, but since a new timeline is created each time, they are all different. She can not come back and meet another of herself because they would both be in a different timeline; MWI creates a new timeline automatically.
In CTC there is only one timeline and a timeloop can not repeat. A repeat would mean more than one Anne, repeat and gen another Anne, and another and more, never ending. This repeating Anne causes a divergence (never ends) but only convergent solutions (Anne) can be self consistent.
Another way of looking at CTC is from POV. Repeatability is only observable from an omniscient POV because there is only one loop in Anne's POV. Special Relativity assure there is not a preferred POV so omniscient is invalid since it implies a preference.

Note my arguments are not completely accurate but should be good enough for most readers.


----------



## Ergodic Mage (Jan 23, 2012)

swolf said:


> Sure, if we 'stop thinking,' linearly or otherwise, then we won't encounter any paradoxes. Basically, what you're saying is, 'This doesn't break the rules if you forget about the rules.'


At this point we do not know what all the rules are; partially because we do not have a _sufficient_ definition of time.



swolf said:


> This same ignoring of logic could be applied to the Grandfather Paradox. If I go back in time and kill my grandfather, it doesn't matter that I will never be born, because I had to have been born in order to kill him.


In MWI this would be allowable as the timeline of your birth would be different from the timeline after killing your grandfather. In CTC this would not be self-consistent and the probability of it becomes zero.


----------



## PaulLev (Nov 2, 2012)

Ergodic Mage said:


> In MWI this [grandfather paradox] would be allowable as the timeline of your birth would be different from the timeline after killing your grandfather.


Right. But the problem with MWI is that it's ad hoc in relation to the grandfather paradox - it's a convenient rabbit to pull out a hat to resolve the paradox. Alternatively, if MWI existed all the time, with or without time travel, we would be living in a universe far more bizarre than even our universe with time travel would be.

Meanwhile, apropos time travel, I today sold my "The Chronology Protection Case" (novelette first published in 1995 in Analog) to its 5th reprint publication, The Mammouth Book of Time Travel Science Fiction anthology, to be published next year.


----------



## ElisaBlaisdell (Jun 3, 2012)

And then there's always another way to solve the "killing your grandfather" paradox.

He went to his papa to make it a date
His papa shook his head and to this he did say
"You can't marry that girl, I have to say no,
"Cause the girl is your sister, but your mama don't know."

He went to his mama. He covered his head.
He told his mama what his papa had said.
His mother she laughed, she said "Go, man, go!
"Your daddy ain't your daddy, but your daddy don't know."

Might be a tad more dangerous to try to murder your grandmother....


----------



## PaulLev (Nov 2, 2012)

ElisaBlaisdell said:


> And then there's always another way to solve the "killing your grandfather" paradox.
> 
> He went to his papa to make it a date
> His papa shook his head and to this he did say
> ...


Ha! Good point, indeed - is that your poem?

I should also point out that murder need not be part of the equation, either. All the time traveler has to do is get in the way of his grandparents meeting, to invoke the paradox.


----------



## Rashaad Bell (Oct 7, 2011)

PaulLev said:


> Ha! Good point, indeed - is that your poem?
> 
> I should also point out that murder need not be part of the equation, either. All the time traveler has to do is get in the way of his grandparents meeting, to invoke the paradox.


Would he have to delay the meeting of the grandparents or change the time of conception?

When Anne gets pregnant, I would assume it would have to be at the exact same time, each time, otherwise it wouldn't be the same sperm and egg to connect and become "her"


----------



## PaulLev (Nov 2, 2012)

Rashaad Bell said:


> Would he have to delay the meeting of the grandparents or change the time of conception?
> 
> When Anne gets pregnant, I would assume it would have to be at the exact same time, each time, otherwise it wouldn't be the same sperm and egg to connect and become "her"


Yah, all the traveler would have to do to invoke the paradox is get in the way of his or her grandparents having sex at the exact same time that they did the first time - since, as you correctly say, there's a different complement of sperm in every shot and actually a different egg every month for the mother.


----------



## Claudia Lefeve (Dec 17, 2010)

Immediately think of the bootstrap paradox (already explained in this thread), also known as an ontological paradox. 

It's like the movie Somewhere in Time. The pocket watch goes exists without ever having an initial starting point.


----------



## Shaun4 (Jun 29, 2012)

I don't have nearly the scientific (Bio or Physics) knowledge that others are dropping, but from the perspective of a casual time travel fan I think you could make that story work.

Anne exists in a loop with no beginning or end. Every iteration of Anne gets the exact same 50% of Mother Anne's genes and the exact same 50% of Father's genes, and the result is always 100% Anne. There in no outside parent of Anne-1, and there isn't much point into overthinking it as Anne-1, Anne-2, Anne-n. There is simply Anne, looping infinitely in the exact same life every time, never changing the loop because any change to the loop would make her existence impossible. The slightest change in any way would alter which genes each parent contributes. If they procreate 5 milliseconds later than they're supposed to, the resulting child could turn out to be a male. So every loop is identical. in this kind of loop, ther is no free will, only following the course of destiny down to the last millisecond.

This made me think about The Terminator. Do you guys think the 5 different actors who played John Connor could each exist in a different universe, based on the randomness of which sperm met which egg in each loop?


----------



## Claudia Lefeve (Dec 17, 2010)

Shaun4 said:


> Anne exists in a loop with no beginning or end.


Exactly! No starting point...it just continues to loop. At least, that's how I see it.


----------



## ElisaBlaisdell (Jun 3, 2012)

PaulLev said:


> Ha! Good point, indeed - is that your poem?
> 
> I should also point out that murder need not be part of the equation, either. All the time traveler has to do is get in the way of his grandparents meeting, to invoke the paradox.


Not my poem! It's a Callypso song I ran across somewhere or other: "Shame and Scandal in the Family."

But, back to time travel. The approach I like is the one where the time traveler's supposed disruption of events is, in fact, what makes things happen "the way they always happened." So, the attempt to disrupt the meeting of one's grandparents, (very Rube Goldbergish try at suicide), turns out to add the spice of challenge that ensures that those grandparents will get together and stay together.

In another genre, think of Oedipus Rex_, _ where the prophecy does not serve as the means to avoid the disaster, but is the trigger for the disaster.


----------



## Rashaad Bell (Oct 7, 2011)

What if Anne, after she drops the baby off, grows up and is the one that triggers the time travel event because she knows her younger self needs to give birth in the past to keep her/older Anne in the current timeline?


----------



## PaulLev (Nov 2, 2012)

ElisaBlaisdell said:


> But, back to time travel. The approach I like is the one where the time traveler's supposed disruption of events is, in fact, what makes things happen "the way they always happened." So, the attempt to disrupt the meeting of one's grandparents, (very Rube Goldbergish try at suicide), turns out to add the spice of challenge that ensures that those grandparents will get together and stay together.
> 
> In another genre, think of Oedipus Rex_, _ where the prophecy does not serve as the means to avoid the disaster, but is the trigger for the disaster.


That's my favorite approach, too - the time traveler goes back in time to prevent something from happening, and the very attempt to prevent the event ironically causes it to happen. There's something exquisite and searing about that.


----------



## PaulLev (Nov 2, 2012)

Shaun4 said:


> This made me think about The Terminator. Do you guys think the 5 different actors who played John Connor could each exist in a different universe, based on the randomness of which sperm met which egg in each loop?


Sure - that could work.


----------



## PaulLev (Nov 2, 2012)

Rashaad Bell said:


> What if Anne, after she drops the baby off, grows up and is the one that triggers the time travel event because she knows her younger self needs to give birth in the past to keep her/older Anne in the current timeline?


Yes, that could work in the MWI schema, as Ergotic Mage described above.


----------



## swolf (Jun 21, 2010)

PaulLev said:


> That's my favorite approach, too - the time traveler goes back in time to prevent something from happening, and the very attempt to prevent the event ironically causes it to happen. There's something exquisite and searing about that.


I like that too. There was a Twilight Zone episode (2002 version) where a woman (Katherine Heigl) goes back in time to kill Hitler as a baby. She becomes the Hitlers' housemaid, but she can't bring herself to kill an infant. Finally, she jumps into the river with the baby, killing it along with herself. Another housemaid sees her do this, and wants to spare the family the sorrow, so she buys a baby from a homeless Gypsy woman, and substitutes it, thereby putting the real Adolf Hitler in place.


----------



## swolf (Jun 21, 2010)

Speaking of going back in time to kill Hitler, I've always been fascinated with this idea, and I wondered, if time travel was possible, what it would be like from young Hitler's point of view, with people constantly popping up trying (and failing) to kill you.  

So I wrote a short story about it, but decided that Hitler was too controversial, so I created Maxwell Madison, a charismatic teen and future President of the United States who turns into a tyrant and plunges the world into war, killing billions.  His entire life he's escaped death by the skin of his teeth, but finally he runs into a time traveler who uses a different tactic - love.


----------



## PaulLev (Nov 2, 2012)

swolf said:


> Speaking of going back in time to kill Hitler, I've always been fascinated with this idea, and I wondered, if time travel was possible, what it would be like from young Hitler's point of view, with people constantly popping up trying (and failing) to kill you.
> 
> So I wrote a short story about it, but decided that Hitler was too controversial, so I created Maxwell Madison, a charismatic teen and future President of the United States who turns into a tyrant and plunges the world into war, killing billions. His entire life he's escaped death by the skin of his teeth, but finally he runs into a time traveler who uses a different tactic - love.


My advice - seriously - is that you rewrite the story as you originally wanted to, with Hitler, and with details therefore different from the Madison story, and publish the Hitler story. Real controversies are good stuff for fiction.


----------



## Rashaad Bell (Oct 7, 2011)

Hugh Howey said:


> When does Anne change her name to Mary?


Anne and Mary are two separate people. Anne is the biological mother/child, Mary is the adoptive mother...


----------



## WHDean (Nov 2, 2011)

Rashaad Bell said:


> Through time travel, can a person give birth to themselves?
> 
> Example: Tom and Mary find a baby on their doorstep. They name the baby Anne. Anne grows up, is now twenty years old and becomes pregnant. Just before birth, Anne is thrown back in time twenty years. Anne has the baby, seeks out Tom and Mary and leaves the baby on the doorstep. Tom and Mary find a baby on their doorstep. They name the baby Anne.
> 
> I think that's possible. Person I'm arguing with says you can't give birth to yourself. What do you think?


Baby Anne who appeared on the doorstep must *causally precede * adult Anne who placed her there, and there's no getting around that physical fact. Someone other than Anne has to have given birth to Anne. So the temporal paradox is really beside the point because Anne can't have given birth to herself *in any possible universe * governed by the same physical laws.


----------



## jasonzc (Dec 23, 2011)

Rashaad Bell said:


> Through time travel, can a person give birth to themselves?
> 
> Example: Tom and Mary find a baby on their doorstep. They name the baby Anne. Anne grows up, is now twenty years old and becomes pregnant. Just before birth, Anne is thrown back in time twenty years. Anne has the baby, seeks out Tom and Mary and leaves the baby on the doorstep. Tom and Mary find a baby on their doorstep. They name the baby Anne.
> 
> I think that's possible. Person I'm arguing with says you can't give birth to yourself. What do you think?


Sounds like good time travel writing to me. I wouldn't worry about paradoxes. Time travel is full of them.


----------



## Ergodic Mage (Jan 23, 2012)

PaulLev said:


> Right. But the problem with MWI is that it's ad hoc in relation to the grandfather paradox - it's a convenient rabbit to pull out a hat to resolve the paradox. Alternatively, if MWI existed all the time, with or without time travel, we would be living in a universe far more bizarre than even our universe with time travel would be.


Agreed, MWI has many problems.
1. It is unbounded (never ending timelines)and all evidence suggests the universe is bounded.
2. To create a whole universes requires exact duplication at the quantum level, which violates Heisenberg's Uncertainty Principle.
3. Even if an exact duplication is possible the "signal" to create a new universe would need to occur instantaneously throughout the entire universe. Exchange of information is through mass or energy and neither can travel faster than the speed of light.



Rashaad Bell said:


> What if Anne, after she drops the baby off, grows up and is the one that triggers the time travel event because she knows her younger self needs to give birth in the past to keep her/older Anne in the current timeline?





PaulLev said:


> Yes, that could work in the MWI schema, as Ergotic Mage described above.


Actually it is possible with self-consistent CTC, if "future" Anne has memories of being helped. Even if she didn't realize it, she could still be a trigger as long as she was not detected.



PaulLev said:


> Yah, all the traveler would have to do to invoke the paradox is get in the way of his or her grandparents having sex at the exact same time that they did the first time - since, as you correctly say, there's a different complement of sperm in every shot and actually a different egg every month for the mother.


The Self-Consistency Principle does not allow changes in history but does allow alterations. Please don't ask me the difference as it'll show my ignorance. OK an IMO guess (don't ask for a proof), the differnece has to do with the relevance of the altered/changed affect to the time travel sequence.
If that's valid then the time of sex (and exchange of chromosomes and dna) may not be as relevant and becomes an alteration instead of a change.
Another way of alteration may be that the traveler becomes mistaken of who his grandfather was, you know grandma had many close male friends and well things did happen in the past. Or he didn't know grandpa was a twin, because the twin died in 1948 from complication of a taser shot.



WHDean said:


> Baby Anne who appeared on the doorstep must *causally precede * adult Anne who placed her there, and there's no getting around that physical fact. Someone other than Anne has to have given birth to Anne. So the temporal paradox is really beside the point because Anne can't have given birth to herself *in any possible universe * governed by the same physical laws.


A very relevant point and self consistency states that the laws of physics must be obeyed locally (and the sum of all solutions obey them globally). But there is a billiards example which shows there may be other solutions to the situation which are self-consistent and only one is needed for the sequence of events to have a non-zero probability.
So you are absolutely correct in that your solution is inconsistent and time travel for it is not possible. But there are still other solutions which may work; Anne brings exact cloning technology with her, or knowledge of how to select chromosomes and dna combinations at the time of conception. These may alter the conception event (what a way of stating it) but not necessarily change it nor change the outcome of the situation as a whole.

A tangent question: can anyone explain why my kids call me a geek? ha


----------



## Rashaad Bell (Oct 7, 2011)

Ergodic Mage said:


> Agreed, MWI has many problems.
> 1. It is unbounded (never ending timelines)and all evidence suggests the universe is bounded.
> 2. To create a whole universes requires exact duplication at the quantum level, which violates Heisenberg's Uncertainty Principle.
> 3. Even if an exact duplication is possible the "signal" to create a new universe would need to occur instantaneously throughout the entire universe. Exchange of information is through mass or energy and neither can travel faster than the speed of light.
> ...


Hmm...okay, so would this work?

Anne (a) grows up. Is kidnapped by an older Anne (b) who does artificial insemination on Anne (a) and sends her into the past.

Anne (a) now becomes Anne (b)

Anne (b) places the baby on the doorstep. the baby now becomes Anne (a)

Anne (b) waits until Anne (a) grows up and does artificial insemination on Anne (a) and sends her in the past. Anne (b) does this because she likes the timeline that Anne (b) lives in and doest want it to change.

Anne (a) is now in the past and has the baby. Anne (a) now becomes Anne (b)

Does that violate anything? Will a regular nontime travel fanboy/fangirl call bs on that theory?


----------



## ♨ (Jan 9, 2012)

WHDean said:


> Baby Anne who appeared on the doorstep must *causally precede * adult Anne who placed her there, and there's no getting around that physical fact. Someone other than Anne has to have given birth to Anne. So the temporal paradox is really beside the point because Anne can't have given birth to herself *in any possible universe * governed by the same physical laws.


Time travel changes all that. If you can bend time, you can create a loop.










Since the loop is a circle, it has no beginning and no end. Thus, Anne can give birth to herself because her birth precedes her life which precedes her birth.


----------



## telracs (Jul 12, 2009)

sorry, Dan, some of us want to know what comes BEFORE the loop.  how does Anne Prime get born?  what happens to "her" mother?


----------



## ♨ (Jan 9, 2012)

telracs said:


> sorry, Dan, some of us want to know what comes BEFORE the loop. how does Anne Prime get born? what happens to "her" mother?


There is no before. The loop always existed that way.


----------



## telracs (Jul 12, 2009)

Dan C. Rinnert said:


> There is no before. The loop always existed that way.


nope..... i'm not a believer in spontaneous creation.


----------



## ♨ (Jan 9, 2012)

telracs said:


> nope..... i'm not a believer in spontaneous creation.


There's no spontaneous creation. I think perhaps you're assuming that time only goes one way. If time travel is possible, then time goes both ways. So, something can happen in the future that causes something that happened in the past. Because an effect happened in the past doesn't mean the cause had to happen in the past as well.


----------



## Nope (Jun 25, 2012)

.


----------



## Ergodic Mage (Jan 23, 2012)

Rashaad Bell said:


> Hmm...okay, so would this work?
> 
> Anne (a) grows up. Is kidnapped by an older Anne (b) who does artificial insemination on Anne (a) and sends her into the past.
> 
> ...


The artificial insemination is self-consistent, but future Anne may need to bring the sperm back in time with her to avoid an Ontological Paradox. The Predestination Paradox could be invoked, but predestination may be argued against using the probability of the time travel itself.
The problem I see is with repeatability. Now I may be wrong here, but the problem I have is that repeating the same sequence of events is divergent - it grows infinitely. Each iteration of a time loop the events would have to be altered such that they become larger than the history of the events (In mathematical terms H/E -> 0).

Now will readers argue and call bs, I give that a 99.9999999% probability, ha. People here have made that clear and with some very good logical arguments. But IMO quantum physics has been mocking human logic for almost 100 years, it has alot of experience and has perfected its evil cackle.



Dan C. Rinnert said:


> There's no spontaneous creation. I think perhaps you're assuming that time only goes one way. If time travel is possible, then time goes both ways. So, something can happen in the future that causes something that happened in the past. Because an effect happened in the past doesn't mean the cause had to happen in the past as well.


As recent as 7 months ago I would have agreed that time can travel backwards, the laws of physics are invariant to the direction of time, mathematical physics works with time moving backwards.
But then I ran across this article which (if proven) gives a physics explanation of where spacetime comes from, the implications could be even more than the Higgs Boson!!!!! One thing that comes out of this that the asymmetrical time (moves only forward) does derive from the hypothesis. In this case di Sitter space is mocking the entire scientific community.
But this does not necessarily rule out time travel because solutions to General Relativity allow for Traversable Wormholes which can potentially transfer between two time periods instantaneously.

Another tangent: My oldest son was laughing at me thinking about this. I explained the thread and his response was "no you cant, incest is wrong".


----------



## ElisaBlaisdell (Jun 3, 2012)

telracs said:


> sorry, Dan, some of us want to know what comes BEFORE the loop. how does Anne Prime get born? what happens to "her" mother?


There's no 'Anne Prime.' There's only one Anne, at various stages of her life. Her mother is Anne.


----------



## swolf (Jun 21, 2010)

Dan C. Rinnert said:


> There's no spontaneous creation. I think perhaps you're assuming that time only goes one way. If time travel is possible, then time goes both ways. So, something can happen in the future that causes something that happened in the past. Because an effect happened in the past doesn't mean the cause had to happen in the past as well.


Since time travel is only theoretical, we fiction writers get to make up our own rules when dealing with it. However, those rules have to make some kind of sense in the readers' minds, or they're not going to accept the pretext. I think the concept of a time loop 'just happening' with no originating cause, is going to be a hard sell to readers. In my opinion, it borders on deus ex machina, where the author is just making up something to solve or create a plot point, with no explanation for why it occurred.


----------



## WHDean (Nov 2, 2011)

Ergodic Mage said:


> A very relevant point and self consistency states that the laws of physics must be obeyed locally (and the sum of all solutions obey them globally). But there is a billiards example which shows there may be other solutions to the situation which are self-consistent and only one is needed for the sequence of events to have a non-zero probability.
> So you are absolutely correct in that your solution is inconsistent and time travel for it is not possible. But there are still other solutions which may work; Anne brings exact cloning technology with her, or knowledge of how to select chromosomes and dna combinations at the time of conception. These may alter the conception event (what a way of stating it) but not necessarily change it nor change the outcome of the situation as a whole.


The billiard ball example doesn't support the self-creating Anne example, because the latter violates the laws of physics, but the former doesn't. Like the slingshot that delivered the billiard ball in the example, Anne could go back in time and punch herself in the face. But she couldn't go back in time and give birth to herself because she couldn't give birth to herself, period.



Rashaad Bell said:


> Anne (a) grows up. Is kidnapped by an older Anne (b) who does artificial insemination on Anne (a) and sends her into the past.
> 
> Anne (a) now becomes Anne (b)
> 
> ...


This scenario still involves at least one paradox: Anne B's reason for inseminating Anne A disappears once Anne A is inseminated. It's like going back in time to save the life of a loved one. If you go back in time to save them, you lose the reason to go back in the future, so you never go back in the first place.



Dan C. Rinnert said:


> Time travel changes all that. If you can bend time, you can create a loop.
> 
> Since the loop is a circle, it has no beginning and no end. Thus, Anne can give birth to herself because her birth precedes her life which precedes her birth.


Time travel doesn't allow you to violate the laws of physics; the laws of physics allow you to violate linear time. Since Anne giving birth to herself violates the laws of physics, it's impossible everywhere at all times.


----------



## Nope (Jun 25, 2012)

.


----------



## ♨ (Jan 9, 2012)

Ergodic Mage said:


> But then I ran across this article which (if proven) gives a physics explanation of where spacetime comes from, the implications could be even more than the Higgs Boson!!!!! One thing that comes out of this that the asymmetrical time (moves only forward) does derive from the hypothesis. In this case di Sitter space is mocking the entire scientific community.
> But this does not necessarily rule out time travel because solutions to General Relativity allow for Traversable Wormholes which can potentially transfer between two time periods instantaneously.


The article also mentions this: "The theory of gravity, Einstein's general theory of relativity, says that spacetime is like Silly Putty. Vasiliev theory says it is Sillier Putty, possessing too little structure to fulfill even its most basic functions, *such as defining consistent cause-effect relations* or keeping distant objects isolated from one another." [Emphasis added.]

So, spacetime is unable, on its own, to define "consistent cause-effect relations" so if you toss in a variable such as time travel then something like a woman giving birth to herself could happen because spacetime is too weak on its own to prevent it.


----------



## PaulLev (Nov 2, 2012)

C.C. Kelly said:


> Anne giving birth to herself violates simple logic. Paradox, mathematics and theoretical physics are irrelevant. Before you can paint a fence, it must exist. You can't paint empty space and have the fence time travel backwards and materialize inside the paint. Before she can give birth, she must exist, unless she is living her life backwards like Merlin, but that is a play on words, because even Merlin's actions were consistent with the 'forward' movement of time.


But Anne already exists, prior to the time travel. The paradox is invoked when Anne begins to time travel.


----------



## Rashaad Bell (Oct 7, 2011)

PaulLev said:


> But Anne already exists, prior to the time travel. The paradox is invoked when Anne begins to time travel.


Maybe the real question is, does Anne exist prior to time travel or does Anne exist only because of time travel?


----------



## PaulLev (Nov 2, 2012)

Rashaad Bell said:


> Maybe the real question is, does Anne exist prior to time travel or does Anne exist only because of time travel?


There's no reason that you can't begin the story with Anne existing prior to the time travel. Of course, once the story progresses into the time travel, we get into the question of how Anne came into existence in the first place - which gets us in the MWI etc so enjoyably discussed by everyone here.


----------



## Nope (Jun 25, 2012)

.


----------



## PaulLev (Nov 2, 2012)

C.C. Kelly said:


> If it were possible, this would already be a cliche plot (device) and we wouldn't be discussing it.


Absolutely - that's what makes time travel so enjoyable to write and talk about


----------



## R. M. Reed (Nov 11, 2009)

I enjoy a good time travel story, but I always think about something I read years ago. Even if you start and end in the same place on Earth, in a different time, you have to travel very far in space as well. The Earth moves around the sun, the sun moves within the galaxy, and the galaxy moves within the universe. You have to find the tiny dot that is the Earth in the whole universe and travel to where it was, or will be, in the time period you go to.


----------



## Nope (Jun 25, 2012)

.


----------



## Ergodic Mage (Jan 23, 2012)

R. M. Reed said:


> I enjoy a good time travel story, but I always think about something I read years ago. Even if you start and end in the same place on Earth, in a different time, you have to travel very far in space as well. The Earth moves around the sun, the sun moves within the galaxy, and the galaxy moves within the universe. You have to find the tiny dot that is the Earth in the whole universe and travel to where it was, or will be, in the time period you go to.


QFT. "I'm the first person to travel in time. Something is missing? Doooh - ahhhhhh"



Dan C. Rinnert said:


> So, spacetime is unable, on its own, to define "consistent cause-effect relations" so if you toss in a variable such as time travel then something like a woman giving birth to herself could happen because spacetime is too weak on its own to prevent it.


I missed that inference, thank for pointing it out! I generally avoid causality discussions as the common views are too inflexible from my perspective.
Besides a possible definition of spacetime, I've concentrated on the field portion to work out a semi-hard wormhole technology for gaming and writing.

As I stated before, people have made good, logical arguments that Anne can not create herself as it would violate physical laws or "laws of the universe". This is such a good point that I spent some time contemplating it in the time-traveling reference. There turns out to be a very simple response, so simple it's embarrassing I did not see it sooner.
Conception is a biological _process_, not a physical law. It can be altered or even violated, which gives rise to birth defects, mutations and so forth.
Self-Consistency (if it is valid) requires that the laws of physics are not violated locally (throw in that term again); there is no constraint or rule about altering a physical processes. So as improbable and illogical as it seems there is just enough wiggle room to avoid a paradox.



Rashaad Bell said:


> Maybe the real question is, does Anne exist prior to time travel or does Anne exist only because of time travel?


Interesting question. I think Anne only exists because of the time travel. Also Anne can exist after the time travel event and should not be constrained after the "loop" ends. She can live a merry life writing best selling novels about impossible time travelers.



PaulLev said:


> Absolutely - that's what makes time travel so enjoyable to write and talk about


And another QFT.
It doesn't matter if time travel or Anne is possible or not; only that writers put together good stories that readers enjoy. Hopefully my geeky ramblings have been of some help.


----------



## WHDean (Nov 2, 2011)

Ergodic Mage said:


> Conception is a biological _process_, not a physical law. It can be altered or even violated, which gives rise to birth defects, mutations and so forth.
> Self-Consistency (if it is valid) requires that the laws of physics are not violated locally (throw in that term again); there is no constraint or rule about altering a physical processes. So as improbable and illogical as it seems there is just enough wiggle room to avoid a paradox.
> Interesting question. I think Anne only exists because of the time travel. Also Anne can exist after the time travel event and should not be constrained after the "loop" ends. She can live a merry life writing best selling novels about impossible time travelers.


Anne can go back in time and kick her pregnant mother, but she can't do the kind of damage that would prevent her future self from being able to form the intent and have the ability to travel in time. That's the physical law being violated: affecting the necessary conditions for your future self. For example, Anne couldn't go back in time and kill her infant self or her grandfather or any other necessary condition for her own existence. Can't happen.

The billiard ball example muddies the water because the trajectory of the ball and Anne manipulating her own timeline are not identical cases. The agent behind the ball and its trajectory is operating in one and the same timeframe. He can make the ball collide with itself because he's the one controlling the ball from an unchanged future standpoint. Anne is affecting her own future.


----------



## PaulLev (Nov 2, 2012)

R. M. Reed said:


> I enjoy a good time travel story, but I always think about something I read years ago. Even if you start and end in the same place on Earth, in a different time, you have to travel very far in space as well. The Earth moves around the sun, the sun moves within the galaxy, and the galaxy moves within the universe. You have to find the tiny dot that is the Earth in the whole universe and travel to where it was, or will be, in the time period you go to.


Most time travel stories just assume that the process of time travel will land the time traveler in same physical part of the Earth or place in which the time travel was initiated. That assumption is no less big than the assumption that time travel itself is possible or could work.

There is a related, smaller issue which I always try to tackle in my time travel stories about what exists in the location in which the traveler arrives. The Time Machine movies - made from H. G. Wells' novel - portray this issue very effectively.


----------



## PaulLev (Nov 2, 2012)

Rashaad Bell said:


> I think ss_muller is on to something.
> 
> The bootstrap paradox is a paradox of time travel in which information or objects can exist without having been created. After information or an object is sent back in time, it is recovered in the present and becomes the very object/information that was initially brought back in time in the first place.
> 
> ...


Just bopping back in here, a year later, to say the archetypal example of this sort of paradox is:

A man knocks on my door. I open it. He tells me he's an older version of myself, who has time travelled back from the future to tell me how to build a time machine. I eventually agree to let him so instruct me, after which he leaves. But I then get caught up in the rest of life, and years go by before I actually construct the machine. But I eventually do, and when it's completed, I travel to the past, to instruct my younger self about how to build this machine.

So ... from where did the knowledge about how to build this machine arise?


----------



## telracs (Jul 12, 2009)

PaulLev said:


> Just bopping back in here, a year later, to say the archetypal example of this sort of paradox is:
> 
> A man knocks on my door. I open it. He tells me he's an older version of myself, who has time travelled back from the future to tell me how to build a time machine. I eventually agree to let him so instruct me, after which he leaves. But I then get caught up in the rest of life, and years go by before I actually construct the machine. But I eventually do, and when it's completed, I travel to the past, to instruct my younger self about how to build this machine.
> 
> So ... from where did the knowledge about how to build this machine arise?


in james hogan's time alteration novel (not time travel really), time lines get overwritten by knowledge from the future....

so, you INVENTED the first time machine in your original time line. but when you went back and instructed yourself, you overwrote that timeline so it appears that the knowledge has no origin.


----------



## PaulLev (Nov 2, 2012)

telracs said:


> in james hogan's time alteration novel (not time travel really), time lines get overwritten by knowledge from the future....
> 
> so, you INVENTED the first time machine in your original time line. but when you went back and instructed yourself, you overwrote that timeline so it appears that the knowledge has no origin.


that's a good solution to the paradox (and better than the more common multiple universes)


----------



## GUTMAN (Dec 22, 2011)

ZacharyBonelli said:


> Rethinking this, I think you're right. And too much of the same genetic material would mean that Anne would come unappealing to her father really quick in subsequent iterations, if he is indeed the same person. I do stand by my original assertion that time jumps *also cause quantum shifts.* Or you could just have paradoxical universes be obliterated and never have existed. Just sayin'.


I come down on the side of quantum shift.


----------



## Vaalingrade (Feb 19, 2013)

The problem isn't Anne, it's Anne's first X chromosome.

Assuming the second X comes from luverddy69, Anne's first has to come from Anne... which came from Anne...Which came from...Anne. This means that Anne's first X chromosome is an artifact around which the stable time loop centers, but which doesn't exist anywhere outside of the loop. It is an anomaly that spontaneously generated from nothing and without some kind of god or god-level reality warper, you can't explain it away.

Using Many Worlds doesn't work either. If Anne Prime was the daughter of Anne Omega and goes on to birth Anne Segunda, Her X chromosome had to still come from somewhere initially and that means every successive Anne would not be the original Anne's genetic duplicate.

Here's one more interesting, scary thing *Anne wouldn't be human* at least not 'our' kind of human, as her she isn't a descendant of mitochondrial Eve and therefore has an entirely different genetic make-up from any human in the last 70,000 years. She is, in short, a monster. And if she has any non-Anne offspring, they will be an alien infestation.


----------



## SBJones (Jun 13, 2011)

I have a character in my trilogy who is in a born again, dies, time travel loop.



Spoiler



In book one I have a character who is actually the daughter of the main two characters from the future who gets her revenge on the main bad guy for killing her. In book two when the main two characters are 'together' her essence/soul is born again to her parents. In book two she is killed by the main bad guy, but resurrected/saved by the time traveling guy and her grandfather and takes the form of the character in book one. In book three she follows the main bad guy back in time to before book one. In book one she gets her revenge on the main bad guy for killing her...



She's born from the same parents so there isn't any genetic stacking like being your own father has. It also plays with having a soul so that's my cheat to rationalize how it's possible.


----------



## GearPress Steve (Feb 4, 2012)

Wow, what an interesting thread. Has anyone watched the film "Timecrimes"?


----------



## jdcore (Jul 2, 2013)

Vaalingrade said:


> The problem isn't Anne, it's Anne's first X chromosome.
> 
> Assuming the second X comes from luverddy69, Anne's first has to come from Anne... which came from Anne...Which came from...Anne. This means that Anne's first X chromosome is an artifact around which the stable time loop centers, but which doesn't exist anywhere outside of the loop. It is an anomaly that spontaneously generated from nothing and without some kind of god or god-level reality warper, you can't explain it away.
> 
> ...


Would it not also be the case that she would have no genetic input from anyone other than her father, and that she would in a sense be a female clone of the father? In effect, she would not be her own mother as she would (genetically speaking) have no mother?

Disclaimer: I may be talking out of my hat. Damn it, Jim, I'm a writer, not a doctor.


----------



## telracs (Jul 12, 2009)

jdcore said:


> Would it not also be the case that she would have no genetic input from anyone other than her father, and that she would in a sense be a female clone of the father? In effect, she would not be her own mother as she would (genetically speaking) have no mother?
> 
> Disclaimer: I may be talking out of my hat. d*mn it, Jim, I'm a writer, not a doctor.


by definition, a clone is a genetic copy, so if you have a clone of a male, it has to be a male...

i still think the only way it would work is if we have an overwrite situation. Anne Prime had a different mother....


----------



## jdcore (Jul 2, 2013)

telracs said:


> by definition, a clone is a genetic copy, so if you have a clone of a male, it has to be a male...
> 
> i still think the only way it would work is if we have an overwrite situation. Anne Prime had a different mother....


Well, no, that's not exactly true. A clone is made from the genetic material of only one donor. To be a male, there would have to be a Y chromosome present, but if the sperm which impregnated the female egg had a Y chromosome, the offspring would be female and it would have only one genetic donor. Ergo, a female clone of a male donor.

Unless I'm missing something.


----------



## Vaalingrade (Feb 19, 2013)

Heh. So she's basically X-23 

It would take some SCIENCE! (and in no way could happen naturally, because there still has to be an egg with an X-chromosome involved), but that _would_ solve the paradox.

If Anne is inseminated with a child whose genetic mother is not Anne or any iteration of Anne, it then become possible for a time traveling Anne to give birth to herself, whether Anne is a female clone of her father or not.

She can just never be her own genetic mother.

Edit: An 'opposite sex clone' isn't, technically a clone. She would have both of her father's X chromosomes, which can theoretically be done in a lab and you do sometimes have natural born humans with XXY because of random providence in the fallopian tubes.


----------



## telracs (Jul 12, 2009)

jdcore said:


> Well, no, that's not exactly true. A clone is made from the genetic material of only one donor. To be a male, there would have to be a Y chromosome present, but if the sperm which impregnated the female egg had a Y chromosome, the offspring would be female and it would have only one genetic donor. Ergo, a female clone of a male donor.
> 
> Unless I'm missing something.


if a sperm impregnated an egg, it's not a clone.

and i don't want to think about the genetic problems a single X person would have.


----------



## jdcore (Jul 2, 2013)

telracs said:


> if a sperm impregnated an egg, it's not a clone.
> 
> and i don't want to think about the genetic problems a single X person would have.


In the scenario described, the sperm impregnates an egg which has only genetic input from one donor. It would still have an X chromosome, but the X would be the same X with the same DNA as the father. Clones are made by removing the genetic info from an egg, and implanting the genetic info from the subject being cloned. That's exactly what would be happening in the scenario described, except that half of the genetic info (absent any Y chromosomes) would be coming from the father.


----------



## The Hooded Claw (Oct 12, 2009)

I'm not sure the girl is a closed loop. Closed loops have been used in time travel fiction before, notably by Harry Harrison in The Stainless Steel Rat Saves the World (highly recommended, but it is third in a series, and the previous two books should be read first). But for a proper loop, something has to take place so that the person has no beginning nor end, just a series of steps that exist in time, with some method of time travel moving the person from her latest date in the time stream back to the earliest point in the time stream. Unless you believe that a new universe is spawned each time (which might happen, depending on the (undiscovered so far, and possibly ever) mechanics of time travel) there is no need for multiple copies of the person. It makes my head hurt, there's no explanation for where the person came from, and it may not actually be possible. We don't know enough about time travel to have any knowledge. Personally, I doubt it is possible, even though I loved the Harrison story.

The reason the girl in the OP isn't a closed loop is that she still exists after she places the infant version of herself on the doorstep. Rather than a closed loop that merges back into the beginning of itself like a ring, she is like one of those loop-the-loops on old Hot Wheels! sets:










After she places herself on the doorstep, she still exists as an adult, and will have some fate elsewhere in time, whether she returns to the future she came from, or lives out her adult life starting again in the time that was her childhood the first time around! If she hangs around in her childhood years, there are paradoxes galore possible if the adult version interferes with her childhood and creates a childhood different than what she originally started out with. This has been in numerous stories, not just in books, but in the Kim Possible animated series, the Casey and Andy webcomic, and gazillions of other places, some of which are better known.









(the above is foreshadowing from a Casey and Andy strip on the subject)

Are closed loops possible? We don't know enough about time travel to know. Personally, I doubt it, but I have no evidence other than my subconscious screaming "NO!" about it, due to the same uneasiness telracs and others have expressed about having no beginning and end.

Though I ADORE time travel stories, my personal hunch (I don't have any factual basis for it) is that (assuming time travel is possible at all) once time travel is invented, people will be unable to resist going back and changing the past. If you believe this spawns separate parallel universes, that's fine, though as someone who had physics training long ago, I want to have a few words with you about conservation of mass. If parallel universes are created, we can merrily change the past with reckless abandon. Assuming you believe that there are NOT parallel universes created, eventually it is likely, perhaps inevitable, that someone will end up changing the past in a way that causes time travel never to be invented. Then things stabilize. Until further down the time stream someone ELSE invents time travel and it starts all over again! The end result is that you will may end up with a world that goes through its whole history with time travel never having been invented. Of course, if you allow for technological civilizations on alien worlds, possibly millions of them, that have the chance to invent time travel, things get very unstable until they settle down everywhere! 

Just to complete the fun, you ought to look up on Youtube (or pull it out of your CDs/MP3s/vinyl disks) the song "I'm My Own Grandpa" by Ray Stevens and many others. Doesn't involve time travel, but is equally confusing!


----------



## PaulLev (Nov 2, 2012)

The Hooded Claw said:


> We don't know enough about time travel to have any knowledge. Personally, I doubt it is possible, even though I loved the Harrison story.


I agree with you completely about time travel likely being impossible, but being immensely enjoyable to read (and, in my case, to write).

Part of the problem is the "travel" in time travel is a word taken from what we do through space - on and now off our planet - every day - and used as metaphor to describe a hypothetical movement backward and forward (beyond just living) in time. But metaphors are never complete mathematical identities. They work by applying a characteristic of one environment to help us better explain another environment. So we say "time flies" to help us understand what feels like the rapid passing of time. But no one looks for watches or clocks flying in the sky like birds. And the same is true of time travel - it works for fiction, but actually expecting to build a time travel machine is akin to looking for clocks with wings in the sky.

Meanwhile, the paradoxes that time travel engenders - be they grandfather, where did the idea come from, etc - can only be resolved by constructs (like multiple worlds) even more far-fetched than time travel itself.

So we arrive at the recognition that time travel is likely impossible but definitely, even exquisitely, enjoyable as fiction.


----------



## Vaalingrade (Feb 19, 2013)

The Hooded Claw said:


> This has been in numerous stories, not just in books, but in the Kim Possible animated series


There is a LOT of discussion that could be had just about how the Tempus Simia


Spoiler



being destroyed


 wiped every use of it out of existence. I've seen discussion about how it is unstuck in time itself, so if it is destroyed EVER, it is destroyed across the entire timeline.

All this to say 'hey, I own that on DvD!'.


----------



## Mark E. Cooper (May 29, 2011)

I love time travel stuff. Check this out http://youtu.be/e99vsYHIbsQ?t=17m34s


----------

