Would it be possible to prove or disprove the possibility of time
travel through the creation of a computer simulation similar to what I
expand upon below? Why or why not?

For example, I thought it would be interesting if someone
created a 3D virtual universe with a vehicle that can travel at, or
faster than, the speed of light. (I'm assuming the simulation
accurately depicts distances and speed.) The user of the simulation could
choose to view outside the cockpit window from inside the vehicle.
(Basically act as a passenger.) To test to see if time travel is
possible, the user could set something to run (a virtual clock or
aging man maybe?) outside the vehicle at the start point.
They would also set a similar item to run inside the vehicle. The user
would then drive/fly the vehicle away from the clock or man at, or
near, the speed of light for a while. Then the user would turn the
vehicle around and race it back to the clock or man. Once he/she gets
back to the clock or man, would they see that more time has passed at
the start point than in the vehicle? 

This could be a completely stupid question so sorry if I wasted your
time. I'm thinking it won't work, but don't know why since it should
just be a question of speed and distance -- things that are frequently
simulated in flying and racing simulators.

---

Clarification of Question by discochicken-ga on 25 Jul 2005 14:06 PDT

I probably should have said "a question of distance and time." instead
of "a question of speed and distance".

Simply speaking theoretically yes, although it is impossible because
according to the theory of relativity states that no object that
starts with a speed lower than the speed of light can travel faster
than the speed of light. That doesn't prevent the universe to contain
something that starts faster than the speed of light and therefor in
reality travels backwards in time. By the sound of your post you may
benefit from a visit to nasa's website
http://spaceplace.nasa.gov/en/kids/phonedrmarc/2003_may.shtml
you will need a flash enabled browser. 

Enjoy the site!

This doesn't really answer your question but it is cool.
It speaks of the "Hafele and Keating Experiment" in 1971. 


http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/airtim.html

grthumongous-ga
I had heard about that experiment and was thinking of it when I
created the post. I didn't know the specifics. I'm just wanting to
know if you could simulate a similar experiement in a virtual world.

elids-ga
I already know some of the basics of time travel theory. My question
is if you could simulate these experiments in a virtual universe or
simulation. In a virtual universe, you could make your vehicle go as
fast as you want it to go. However, I wonder if computing power might
be a stumbling block to getting a virtual vehicle to go the speed of
light.

Thanks for the link though. It is pretty neat.

According to the Bible, time travel is possible, but only with God's
approval. The first example is when Satan offered Jesus 'All the
kingdoms of the world", wealth, fame, etc. for just one act of
obedience to him [Satan]. Of course, Jesus refused.  All the kingdoms
included not only the ones in existence in Jesus' day but all FUTURE
ones. A form of travelling into the future. the second example is at
Revelation 4;1. An angel says to the Apostle John " Come on up here,
and I shall show you the things that must take place". Again, another
form of looking into or maybe even being transported into the future.
Makes you think Eh!.

In a simulation the process would be pretty much the same as in the
real world, after all that is the purpose of a simulation. That means
that we would have to imput the same known facts into the program
running the simulation as those we would see in real life, so you
would wound up with the same results. The theory of relativity states
that if you start with a slower than light speed you can not exceed
the speed of light, so if we imput that into the program running the
simulation the program would crash as you approach the speed of light
as the object would reach infinite mass and that is not computable,
regardless of the speed of the computer.

Now, there are several theories as to how we might sidestep this
inconvinient brick wall. One of the most promising ones is the 'warp'
theory neatly explained by Scientific American on a special issue you
can download it for 7.95 at
http://www.sciamdigital.com/browse.cfm?sequencenameCHAR=item2&methodnameCHAR=resource_getitembrowse&interfacenameCHAR=browse.cfm&ISSUEID_CHAR=6C2FAA19-0087-C3FE-547CDF8E4C786808&ARTICLEID_CHAR=6C3CA070-DB05-5628-AB1A1546F4F9D680&sc=I100322
the basic premise is that we could bend space and although we
ourselves would never violate the theory of relativity and move faster
than the speed of light, because we bent space we would travel
distances measured in light years in a matter of seconds at what would
be for us normal speed within the bubble of normal space surrounding
us within the warped space we've created.

There is one mayor problem to that theory though, although
theoretically possible, calculations were made and to move an object
the size of the space shuttle we would need the same amount of energy
the sun produces every second. That amount of energy is beyond
anything anybody can comprehend, however, for the sake of argument, to
the greeks that at most could comprehend the energy output of an
elephant roughly equivalent to 10 hp the amount of energy we have
controlled when we launched rockets like the Saturn 5 that developed
7.5 million pounds of thrust or 33.4 million newtons (100 newtons=
1hp) it is clear to see that the ancient greeks would've never
envisioned anything capable of developing 334,000 hp...  ;-)

I'm sorry on the previous post I got sidesteped by my own thoughts on
faster than light travel and forgot about the nature of the question;
time travel. Time travel although theoretically possible, it is not
possible for us (since we start with a slower than light speed). We
may 'prove' the concept through experimentation but we can never
achieve the end result of time travel. We may be able to achieve
slower than normal time travel but it will always be in the same
direction from present to the future, we may never reverse the
direction.

elids
You say we would have to input the following two theories or rules in the system.
> If you start with a slower than light speed you can not exceed
the speed of light
> As you approach the speed of light, the object would reach infinite mass

Would you really have to enter those theories or rules for
experimentation purposes? Of course if you enter in a rule that says
you can't go faster than the speed of light if you start slower than
it, the system will crash. But you state this is theory. Let's throw
out that theory. In addition, let's just keep the mass of the vehicle
constant (even if that is impossible in the real world). Now what
happens in the quasi-simulation? (Let's just say we only want to
simulate some aspects, but not all.)

Also, let's say we also use this "simulation" to recreate the exact
same experiment brought up by grthumongous. This experiment basically
demonstrates time travel; however, it is on a minor scale.

Would we be able to see different times on the clocks in this virtual
universe or world? I guess that is what I am really trying to get at.

Well in that case then yes.

If we are going to make up the rules as we go, if we can choose what
to take and what to leave if we can bend some and skip others then yes
anything is possible. But if we were to do such a thing we might as
well just make up a rule that puts Nicole Kidman by my side and she
wiggles her nose and...

If on the other hand we were to make a simulation with the best
information we have on hand, then the answer is no.

"For example, I thought it would be interesting if someone
created a 3D virtual universe with a vehicle that can travel at, or
faster than, the speed of light. (I'm assuming the simulation
accurately depicts distances and speed.) The user of the simulation could
choose to view outside the cockpit window from inside the vehicle.
(Basically act as a passenger.) To test to see if time travel is
possible, the user could set something to run (a virtual clock or
aging man maybe?) outside the vehicle at the start point.
They would also set a similar item to run inside the vehicle. The user
would then drive/fly the vehicle away from the clock or man at, or
near, the speed of light for a while. Then the user would turn the
vehicle around and race it back to the clock or man. Once he/she gets
back to the clock or man, would they see that more time has passed at
the start point than in the vehicle? "

I have some experience in 3D game programming, and all that you ask is
possible... but it's tricky. Simulations work acording to rules you
define. Depending on how you program those rules you can make the user
believe he is traveling in time, or that he is not... just play Star
Wars simulators. On the other hand, I think man knows too few rules
about reality to make an accurate simulation about time travel. So,
you can program the simulation according to theories that say you can
travel in time, or according to theories saying it is impossible...
which rules are true?

But, something interesting you make me think about is how could a
computer deal with a virtual world in which you can travel in time?
You might know Massively Online Games use something called Persistent
Worlds. Many users play at the same time in a virtual world, and that
time advances *almost* at the same rate for everyone... indeed there
are small delays in transmission, etc, but the game tries to keep
everyone syncronized... anyway, the idea is how could the game deal
with someone that goes back in time in a Persistent World? First of
all, to make it real, the game should retrieve all the information
about the entities in the Persistent World at the time in the past the
traveler returned to. Then... and this is the weird part, time for the
traveler must go on, and there are two ways the game could work:
traveler could be forced to repeat everything exactly as he did in the
last hours, and once the traveler gets to the point he warped, he will
return back to the ethernal circle. Not funny at all. To make the game
interesting, the traveler should be allowed to make his actions
different, but that would allow him to change elements in the scene,
creating a whole new Persistend World... now, how could you force
those changes into the players that are playing in the "present"
(remember traveler is somewhere in the "past")?... Would the game be
able to simulate all the consequences for each entity and the players?
That means the game would have to simulate accurately the intelligence
of the other players regarding to all the reactions they will have in
the next hours from past to present. Probably there is a solution to
make it work, like parallel Persistent Worlds, etc. But now you see
how tricky time travel rules could be, and how difficult making a
realistic time travel simulator could get. That doesn't mean it is not
interesting dreaming about time travel... all those possibilities ;D

I agree with what elids said. The programmer determines what equations
the physical system will obey, and current physics theory states that
there is no such spaceship that will travel faster than the speed of
light. If we assume that such a spaceship could exist, we wouldn't
need a computer to tell us time travel is possible. If we assume one
could not, then likewise we already know the answer. No simulation
would help.

This is like asking the same question as Why can not we simulate Human
intelligence on computers.The answer is because we do not know how
human intelligence work so we can not simulate it.

If you want to Simulate somtehing you have to run some kind of
program.And that program has to be programmed by a human.If he doesn`t
now what really happens the simulation will be pointless , isn`t it?

So if one day we can understand fully how Universe works we can
probably simulate what really happens when you time travel.

my 2p, if we are indeed living in an einsteinian universe then
whatever simulation or scenario you will attempt to run will not
confirm the existance of time travel, im no computer expert but i do
not believe it would compute, however if it did the results would be
that you would have aged slower then the clock relatively speaking,
but is this time travel?

If we step out of the Einsteinian universe and into the realms of
quantum mechanics and string theory then time travel is more then
probable, string theory states that we are living in a 10 or 11
dimension universe (depending on which interpretation of the equations
you believe)in this case it is reasonable to assume that all the
dimensions may move in different time frames, unfortunately are brains
are unable to comprehend a higher dimension so i shall use metaphor
for it.

there was once a stick man living in a 2D world, he knew the physics
of forward and backward and left and right. one day a 2D fish appeared
and said to the stick man i can show you a new dimension with up and
down in it and width and breth, even though the stick man was
intelligent he could not tell the difference between forward and up
and breth with left and right, so the fish took him to the 3rd
dimension and showed him, then the stickman understood and was able to
explain it to all the other 2d people.

assuming we one day assertain the knowledge to slip through dimensions
we may also be able to slip through time as we pass through them, but
at the moment we can not possibly comprehend higher dimensions, this
also goes back to what someone else was saying about angels showing
people the future, i am an atheist but i think it is reasonable to
assume there are beings living in higher dimensions if these
dimensions exist, like we have complete power over the 2D world with a
pen and paper beings from higher dimensions may well have complete
control over ours, we just cannot comprehend it yet.

i know i have gone off track a little but i hope it clears some things up,

i just found this quote it seems to sum up my feeligs adequately.

"Is time real?  Does it flow in one direction only?  Does it have a
beginning or an end?  What is eternity?  None of these questions can
be answered to scientists' satisfaction. Yet the mere asking of these
questions stretches our minds, and the continual search for answers
provides useful insights along the way."