# No time-travel but in one's imagination.

#### Wendy

Joined Mar 24, 2008
22,155
My personal opinion is we don't know enough to state that with absolute certainty. Time will tell.

#### thingmaker3

Joined May 16, 2005
5,084
Traveling forward through time is actually pretty easy.

#### Wendy

Joined Mar 24, 2008
22,155
And we even know how to fast forward. Can't do it yet, but we know how.

#### jpanhalt

Joined Jan 18, 2008
10,087
Actually, I thought the original comment related to time being a perception was similar to the ago-old question of whether a tree that falls in the forest when no one is around to hear it still makes a sound. Similar questions exist about color, etc. They all give me a headache.

Of course, we know now that the Vulcan Science Council decided time travel was impossible. That was later disproved by Capt. Gordon Archer who accomplished the feat. John

#### thingmaker3

Joined May 16, 2005
5,084
If predicting the future is a "level III impossibility," then how can time travel be only a "level II impossibility?

#### Dave

Joined Nov 17, 2003
6,970
If predicting the future is a "level III impossibility," then how can time travel be only a "level II impossibility?
Lol! There will be some (weird) logic in there somewhere!

Interestingly, the other Class III impossibility is "perpetual motion machines" - haven't we (allegedly) had a few of these on here over the years?!

Dave

#### antimatter

Joined Apr 16, 2008
3
If predicting the future is a "level III impossibility," then how can time travel be only a "level II impossibility?
Don't take what I tell you as absolute fact, but from what I understand, time travel is only possible in one direction (By current theory), that is, forward. There are several "theoretical" ways to achieve this, while really all your doing is "speeding" up or "slowing" down the rate at which time elapses relative to a fixed point, say earth. Therefore the term "time travel" is debatable, "time dilation" might be more descriptive.

Now, the two ways I understand to travel forward in time are 1)Increase your speed relative to a "fixed" point, i.e. Terra Firma, and/or 2)deposit yourself in a relatively massive gravity well, that is put yourself on the surface of the sun (bring plenty of sunblock). Either of these techniques will cause your wristwatch to tick slower than the same wristwatch on earth, in effect giving you the ability to move forward in time.

The gravity well method requires enough gravitational force to literally crush your body to slime. The acceleration method requires that you approach close to the speed of light, c, in order to achieve substantial time dilation. Well, accelerating a 1-ton payload to 90 percent of the speed of light requires an energy equivalent of at least 3^{10} tons of TNT, 25,000x the largest nuclear bomb in the US arsenal(The B83) and 2^{6}x the bomb the bomb dropped on Hiroshima. Try fitting all that TNT equivalence onto a 1-ton vessel.

Regarding moving backwards in time, I read an interesting article in Scientific American, I believe, regarding using the the above mentioned methods for traveling forward in time and wormholes (Believe it!) Essentially, you create/discover/keep stable 2 quantum connected wormholes, deposit 1 in a gravity well or on the surface of a large(ginormous) object, wait a couple hundred years or so, then pull that wormhole off the gravity well. Since the wormhole that was in the gravity well is technically "younger" than the connected wormhole you kept stored away in the broom closet on earth, traveling through your broom closet wormhole will theoretically transport you to the corresponding time your young wormhole exists in. The only problem is, you can only travel back in time as far as your wormhole can take you, so traveling back to see the dinosaurs or Jesus would be impossible. That is, unless a new working theory comes into play that is just "Impossible!" by today's standards.

Like I said, take the above with a grain of salt, for it is based off my memory of random sci journals and a dash of Google, it is an interesting topic indeed.

#### antimatter

Joined Apr 16, 2008
3
BTW, the above was my first post. I found this forum looking for information on low power 12vdc relays (weird), and I must say I am hooked! Darn great site with surprisingly intelligent people! Expect to hear some rookie questions out of me in the future!

#### studiot

Joined Nov 9, 2007
4,998
A good deal of confusion about the use of numbers arises when we connect Mathematics to Physics. This is because numbers in Physics represent physical quantities, which have physical realisation in some way. Numbers in mathematics are just  well numbers  and dont represent anything but themselves.

So when we draw x,y,z. axes in Mathematics all axes are equivalent, and no segment is special.

But in Physics when we draw axes each has its own special meaning and properties and sometimes only some segments are used (have meaning) although the numbers run on indefinitely.

When we say travel we mean changing the numbers on the axis in some way

So let us examine what we mean by time travel in the light of the 7 diagrams shown in the attachment. All the points can be illustrated in Flatland  We can avoid the complexity of 3 (or more) dimensions.

For many physical quantities the axis is merely a scale we lay against the objects property. Changing the value does not upset the rest of the universe. Many object may have the same value. Values are points on the axis.
For example the masses of cup P and jug Q may both be increased to R by (partly) filling with coffee. The cup and jug have travelled along the mass line.
This is the situation in Fig 1

Fig 2 introduces a body with physical extent along the axis. This might be the length of the blue box, which extends from P to Q.

Moving the box to P Q involves moving the whole box, not just part of it as in Fig 3.

This statement is the crux of time travel as objects have a duration along the time axis and moving the object involves the whole object in the same way.

In Fig 3 we contemplate slicing a section from the middle of the box and displacing it to R. This operation, of course, destroys the integrity of the box. Also we havent move the box just a section and the question arises
How short a section can we move?

Whatever the answer we end up with the situation in Fig 4 with continuity along the axis destroyed.

In time travel terms this picture corresponds to the popular view of time travel with sections of the axis popping off to visit their great great grandfather etc.

In fact a further complication arises as shown in Fig 5.

Where there is only one axis and something else occupies another part of this axis, such as the green box VW we may not be able to make the movement as the green box blocks the blue one, unless it can pass right through like a ghost.

Of course, with spatial dimensions, we have more than one so we can do a sidestep manoeuvre and by pass the blockage as in Fig 6.

We only have one time dimension that we know of.

Finally Fig 7 shows what happens when everything is in its own parallel universe and can slide freely past its neighbour.

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#### beenthere

Joined Apr 20, 2004
15,819
Thanks to the absolute spacial displacement of the earth, time travel might result in an awkward appearance in space some significant distance from where the planet is located relative to the location of the time traveler when he pushed the go button.

#### thingmaker3

Joined May 16, 2005
5,084

If, at dawn tomorrow I time travel (and tele-port per Beenthere's observation) to dusk tomorrow... my momentum is still toward the sun, but the room's is now away from the sun. I slam through the West wall with explosive effect.

You go first, just in case...

#### recca02

Joined Apr 2, 2007
1,214
If predicting the future is a "level III impossibility," then how can time travel be only a "level II impossibility?
The reason for that is someone'll have to first travel into future (level 2) and get back into past (level2) to make a safe prediction.
So,
level3 + lots of \$ = Level 2 + level 2