# If you could travel to the past, before you were conceived, would you? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [August 3, 2015, 7:02pm UTC](https://boards.straightdope.com/t/if-you-could-travel-to-the-past-before-you-were-conceived-would-you/726910 "2015-08-03T19:02:32Z")\ **Posts on this page:** 11\ **Page:** 2
**Author:** ![Siam\_Sam](https://avatars.discourse-cdn.com/v4/letter/s/d78d45/32.png) [@Siam\_Sam](https://boards.straightdope.com/u/Siam_Sam)\ **Post date:** [August 6, 2015, 1:34am UTC](https://boards.straightdope.com/t/if-you-could-travel-to-the-past-before-you-were-conceived-would-you/726910/21 "2015-08-06T01:34:17Z")
> [@cmyk](#): > > I’m trying to think of a way, where I can go back to the upper limit, so as not to incur a butterfly effect where I’ll never be born, and plant a message, explicitly from me, to me, in a place I know I’ll be in 10 years. > > And I think I have it. We lived in a small home with easy access to the creepy attic I used to tinker around in when I was a kid. Its door was right next to my room upstairs. I could probably come up with some convincing information that would prove to my younger self that this is for real (names & dates of specific events to come in the early 80s). Then go on and give stock tips and such to make a killing in my later life. > > I’d have to break into the house before we would move in about 8 years later, but it was there, and I know a spot I’d be sure was not only well hidden, but I would find and use to stash my kid stuff away from my then nosy sisters. Your parents would be put off from moving in by neighbors’ reports about someone seen breaking in some years back, so you would never live there and would turn out to be a completely different person. Or dead due to a tragic fire in the house you did end up in. ---
**Author:** ![Atomic\_Mama](https://avatars.discourse-cdn.com/v4/letter/a/b5ac83/32.png) [@Atomic\_Mama](https://boards.straightdope.com/u/Atomic_Mama)\ **Post date:** [August 6, 2015, 7:55am UTC](https://boards.straightdope.com/t/if-you-could-travel-to-the-past-before-you-were-conceived-would-you/726910/22 "2015-08-06T07:55:16Z")
B. 1949. I would love to see Charley Patton in a Mississippi Delta jook joint. Circa 1931. Or Tommy Johnson, same era & place. 😃🆒 ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [August 6, 2015, 12:51pm UTC](https://boards.straightdope.com/t/if-you-could-travel-to-the-past-before-you-were-conceived-would-you/726910/23 "2015-08-06T12:51:17Z")
This sounds like a surefire way to pull a Fry and become my own grandpa… But I’d do it anyway, just to hear what the Elizabethan English stage accent _really_ sounded like ---
**Author:** ![Just\_Asking\_Questions](https://avatars.discourse-cdn.com/v4/letter/j/ba9def/32.png) [@Just\_Asking\_Questions](https://boards.straightdope.com/u/Just_Asking_Questions)\ **Post date:** [August 6, 2015, 3:32pm UTC](https://boards.straightdope.com/t/if-you-could-travel-to-the-past-before-you-were-conceived-would-you/726910/24 "2015-08-06T15:32:06Z")
I subscribe to the time travel theory that you, the traveler, are immune to changes in the timeline. To wit: You go back to 1955 in your DeLorean, and prevent your parents from getting married. When you travel Back To The Future, your entire life is gone, never happened. No one remembers you, you have no traces left, there is not a hint of a mark you left anywhere in the world during the years you were growing up. You’re not Marty McFly, you’re George Bailey. But you don’t cease to exist! You continue on, an orphan to the world you find yourself in. You continue to live, but just without any history. It would be hard to eat, get a job, but you’re not going to go poof-pift. And should you decide to travel back again, you are traveling back in the past of the NEW world, not your own past. After the point you arrive, it’s all new. Even if you succeeded in getting your parents back together, the minute you traveled back to 1985, those people in your house aren’t YOUR parents. They are at best the parents of the other kid living in the house that looks like you, but isn’t YOU. The timeline with your parents is gone, never existed. You’re still an orphan to the timeline. Given that, I’d go in a heartbeat! (Technically, you’ve violated conservation of mass, as there is now an extra 3000 unaccounted for pounds of mass in the universe. But that’s just nitpicking.) ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [August 7, 2015, 12:36pm UTC](https://boards.straightdope.com/t/if-you-could-travel-to-the-past-before-you-were-conceived-would-you/726910/25 "2015-08-07T12:36:29Z")
> [@cmyk](#): > > You’d create an infinite time loop of existing and not existing! I used to fiddle with that model but couldn’t ever get it to quite work. It requires a second sort of time, one I couldn’t quite make work. The closest I can come is the “time like a river” model, which I’m not quite happy with, especially when you add more time travel and more time travelers. > [@Just\_Asking\_Questions](#): > > I subscribe to the time travel theory that you, the traveler, are immune to changes in the timeline. That’s my favorite model, as it avoids all paradoxes with a simple model that’s easy to visualize. Travel to the past and when you arrive you create a new branch timeline/universe. It’s a cheap model too, if you posit the multiverse! When you travel forward, you ride the same (altered) timeline, and yeah, you become an extra wheel back in your own time: your own twin, if you didn’t prevent yourself being born. No doubt you have to swap mass & energy with the destination to provide conservation. But it’s not a very fun model for fiction. ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [August 7, 2015, 12:57pm UTC](https://boards.straightdope.com/t/if-you-could-travel-to-the-past-before-you-were-conceived-would-you/726910/26 "2015-08-07T12:57:54Z")
[QUOTE=cmyk] We lived in a small home with easy access to the creepy attic I used to tinker around in when I was a kid. Its door was right next to my room upstairs. I could probably come up with some convincing information that would prove to my younger self that this is for real (names & dates of specific events to come in the early 80s). Then go on and give stock tips and such to make a killing in my later life. [/QUOTE] The house I grew up in had a hidden space between walls by the chimney. Access to it was through a little access closet for a built-in TV from the late 50’s. We moved in in 64; I was 7. The thing is, my little brother discovered it, so I’d have to leave him the note. I’d put it in code with the instructions, “Have Jeff decode this!” I’d be sure to warn myself about whats-her-name. This assumes I’m wrong about timelines, and all those silly movies are correct. Or something. Insert magic here. ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [August 7, 2015, 1:07pm UTC](https://boards.straightdope.com/t/if-you-could-travel-to-the-past-before-you-were-conceived-would-you/726910/27 "2015-08-07T13:07:02Z")
> [@cmyk](#): > > I forget off hand, but I wouldn’t chance any further than ~80 million years. I’ll be interested to hear what folks with a clue would say, but I’d guess much longer. Oxygen levels would have been sufficient much farther back, after plants proliferated. Post Cambrian, perhaps? While there would be microbes we wouldn’t have defenses against, they also wouldn’t have evolved to utilize mammalian biology. I’d definitely love to see live Dino’s! But how to do so safely? I’m not too worried about the butterfly effect. While a butterfly in China might cause a hurricane in America, I bet the overwhelming majority of butterflies have no significant impact on the weather. Likewise, most specific events in the far past have diminishingly little impact on the present. ---
**Author:** ![bump](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@bump](https://boards.straightdope.com/u/bump)\ **Post date:** [August 7, 2015, 1:56pm UTC](https://boards.straightdope.com/t/if-you-could-travel-to-the-past-before-you-were-conceived-would-you/726910/28 "2015-08-07T13:56:50Z")
To me, it would depend on whether I was allowed to come back; if I could go and observe historical stuff and come back, that would be amazing. Seems like I could make a good living as a history prof by finding some piece of forgotten or disputed lore in the modern day, and going back to see it first-hand. But I’d do my damnedest to avoid interacting as much as I could; I’m imagining myself hiding out camouflaged like a sniper on a hilltop watching battles unfold, so I could come back and write about it in the present. There’s no way I’d go interact with my relatives who I am aware of. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [August 7, 2015, 2:36pm UTC](https://boards.straightdope.com/t/if-you-could-travel-to-the-past-before-you-were-conceived-would-you/726910/29 "2015-08-07T14:36:16Z")
> [@Learjeff](#): > > I’ll be interested to hear what folks with a clue would say, but I’d guess much longer. Oxygen levels would have been sufficient much farther back, after plants proliferated. Post Cambrian, perhaps? There was [a slow build-up](https://en.wikipedia.org/wiki/Geological_history_of_oxygen), but anywhere after the Cambrian should be survivable, yes (I think below 10% is the threshold for danger). Don’t expect to do any jogging or heavy lifting, though, that’s _really_ high mountain-like partial pressures. So best not piss the dinos off. It’s never been _high_ enough to harm us, either (35% in the Carboniferous is the max, and that’s not oxygen toxicosis levels AFAIK) ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [August 8, 2015, 10:21pm UTC](https://boards.straightdope.com/t/if-you-could-travel-to-the-past-before-you-were-conceived-would-you/726910/30 "2015-08-08T22:21:37Z")
> [@MrDibble](#): > > There was [a slow build-up](https://en.wikipedia.org/wiki/Geological_history_of_oxygen), but anywhere after the Cambrian should be survivable, yes (I think below 10% is the threshold for danger). Don’t expect to do any jogging or heavy lifting, though, that’s _really_ high mountain-like partial pressures. So best not piss the dinos off. > > It’s never been _high_ enough to harm us, either (35% in the Carboniferous is the max, and that’s not oxygen toxicosis levels AFAIK) Thanks! I believe that all through the dino era, oxygen levels were higher than now. Oxygen becomes toxic when the partial reaches about 1.2 atmospheres. Sport diving is generally limited to 100’ depth, which is 4 atm at 20% oxygen (normal air), so that’s about 0.8 atm. That’s a danger limit for exposures measured in hours; perhaps it would be lower for days of exposure. 100% is bad in other ways; fluid builds up in the lungs. No idea what the max long-term health limit is, but even 100% is fine for a while, and 100% at .5 atm is sustainable (we used that for Apollo, I believe.) ---
**Author:** ![Baker](https://avatars.discourse-cdn.com/v4/letter/b/bb73d2/32.png) [@Baker](https://boards.straightdope.com/u/Baker)\ **Post date:** [August 8, 2015, 10:39pm UTC](https://boards.straightdope.com/t/if-you-could-travel-to-the-past-before-you-were-conceived-would-you/726910/31 "2015-08-08T22:39:24Z")
I’d take the chance. I’ve always wanted to meet my maternal grandparents when they were young and courting. Or when, during their first year of marriage, they were sneaking into hotels here in town Their marriage was secret the first year and I remember my grandmother telling me “I still recall how those desk clerks would look at us.” [Previous page](https://boards.straightdope.com/t/if-you-could-travel-to-the-past-before-you-were-conceived-would-you/726910.md?page=1)