
The Utter Failure of Fictional Time Travel - draenei
https://blogs.scientificamerican.com/life-unbounded/the-utter-failure-of-fictional-time-travel/
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lotyrin
Fiction with Primer-style travel solves for this -- you travel to where-when
the machine was when it was started.

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ruytlm
Seems silly to namedrop Doctor Who without acknowledging that the name of the
time machine in the series (the Tardis) is an acronym for Time and Relative
Dimensions in Space - which, you know, kinda directly addresses the allegedly
unaddressed spatial problem outlined in the article.

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mickronome
From a narrative point of view, the spatial problem as stated is a quite
decent post hoc argument for why time travel is usually fraught with danger,
even after the science is known, as predicting the exact parameters needed
would be nigh impossible.

One could easily argue that big whiteboards laden to the brim with integrals
and capital sigma (summation) rich equations indicate a data rich problem
rather than a theory heavy one, and that the inevitable squashed, disappeared,
or exploded melon fits very well into this framework.

Shooting a water melon at several million miles per hour so it hits a small
time travel device correctly in all N>3 dimensions is obviously going to make
a royal mess quite a few times, as evidenced in many movies!

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growt
This absolutely brilliant short story is based on the main point of the
article:
[http://compellingsciencefiction.com/stories/floaterscantfloa...](http://compellingsciencefiction.com/stories/floaterscantfloat.html)

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sowbug
Even if you solve the problem of where to go, I don't know how you ensure that
location is clear of other stuff. If a bunch of air molecules suddenly
appeared inside you, I don't think you'd enjoy it.

This might be why time travel in Terminator movies creates the sphere of
energy right before the traveler appears: it clears out the space. But then
why doesn't the person experience a moment of disruption being inside a
perfect vacuum?

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myrryr
Because it is filled with the air they are moved with.

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zunzun
Go just one hour into the past and you will die in the vacuum of space, as the
air won't be there at that time.

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myrryr
[https://en.wikipedia.org/wiki/Frame-
dragging](https://en.wikipedia.org/wiki/Frame-dragging)

Frame dragging is a good answer. You are locked to the inertial reference of
the nearest big body (add yo mom jokes here if you like).

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antonvs
Yo momma so fat she attracts time travelers from the Andromeda Galaxy.

But I don't think frame dragging solves the problem, at least not without a
complete rearrangement of relativity, in which case you don't really need
frame dragging.

The problem is that frame dragging occurs in the local environment - if you're
being dragged along with a frame, you're not traveling at any unusual vector
through time.

Time travel necessarily deviates from the spacetime path of the frame,
otherwise you'd just be traveling with the frame as normal. And if you deviate
from the path of the frame, then ordinary frame dragging isn't going to help
you. Of course you could perhaps invent some sort of more spooky frame
dragging to handle this case, but it wouldn't have the same physical basis.

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zshrdlu
That's quite an attractive momma.

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perilunar
In HG Wells' case, the Time Machine is resting on the ground and travels with
it. It doesn't ever travel back in time to before it was built. i.e. the
occupant only travels in time to where the machine already exists.

The machine no more needs to calculate its motion through space as it travels
through time than a rock or an old building does.

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lkrubner
You are missing the point. Once you are free of space time there is no gravity
holding you to the surface of the planet, therefore staying on the surface of
the planet requires a propulsion system and tremendous navigational skills.
“Stay where you are” is only easy when you have the help of gravity, and it’s
alwsys an illusion. At no point do you ever stay where you are.

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perilunar
No I’m not. Wells’ time machine is never “free of time and space”. It was
built and then remains in place (more or less) for hundreds of millenia. In
the book the traveller describes watching the world around him change rapidly
as the machine accelerates through time. It doesn’t disappear and reappear
like the TARDIS.

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lkrubner
Do you seriously not realize that the planet is moving? Do you honestly not
get that?

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perilunar
Of course I realise the planet is moving. The Time Machine is also moving, and
in such a way that it retains its exact relative position to the planet.
Amazingly it does this without any means of propulsion, relying instead on
contact forces (weight, friction) generated by the gravitational attraction
between the Machine and the planet.

Seriously, the point is that the Time Machine does not leave our space-time
and appear in another. It simply exists through time, like a building or a
rock or a pyramid. It is a four dimensional object where the Traveller can
move along one of its dimensions.

Anyway, enough arguing about a fictional (and probably impossible) machine.
Read the introduction to _The Time Machine_ if you are interested in how H. G.
Wells explained it:
[http://www.gutenberg.org/ebooks/35](http://www.gutenberg.org/ebooks/35)

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Arbalest
I think many people have already identified this. Considering spatial movement
is dimensional movement (as time is) it isn't hard to imagine this is
compensated for similarly. You're already bending space time to move around in
time, just keep bending it to move in space.

Big deal that fiction doesn't actually detail this, it adds nothing to the
narrative.

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flafla2
I wonder what bumping into someone through time feels like.

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zaknytree
We are in the process of it

