Time Travel Reference Frames

[Lorizael]

Same goes with the center of the galaxy in regard to the sun. The sun is subject to gravitational force of the whole galaxy, and but thus, the center of the galaxy is a more valid reference frame than the sun.

Kind of, if "center of galaxy" is just what's inside the sun's orbit. What's at the center of the galaxy (the supermassive black hole) is not the dominant gravitational force on the sun.

My knowledge of (astro)physics is not sufficient to understand what the expansion of the universe in all directions might have as influence on position over time.

Basically none. The constituents of the galaxy are pretty much all gravitationally bound to each other (with the exception of hypervelocity stars).

[Lorizael]

...so you're siding with popular dumbed-down sci-fi writing?

There's nothing realistic about Wells' time machine.

[The Mad Monk]

But...but...Star Trek!!!

[Lorizael]

Star Trek is rife with problems, the most critical one being that, because they have ftl, they should have constant problems with causality.

[The Mad Monk]

They do!

[Lorizael]

Good point.

[N35t0r]

For a machine that allows 'jumps' through time, it would seem to me that jumping through space at the same time would be relatively trivial.

[The Mad Monk]

What's with this "Unapproved" tag I'm getting?

[The Mad Monk]

A far as "jumping" through space goes, I will refer to the Traveller rules on psionic teleportation:

Teleportation
Teleportation is a talent which allows instantaneous movement from one point to another point without regard to intervening matter. Psionic teleportation is limited to the movement of the teleported character’s body and (for highly skilled teleports) his clothing and weapons.

Teleportation always involves the movement of one’s body to another location. Independent items or other individuals may not be moved. A small animal could conceivably be carried as part of a personal load under the task to teleport one’s self with equipment. (Limited to under 15Kg mass).

Teleportation involves certain requirements in order to be completely accurate, as well as to ensure obedience of the laws of physics.
Foreknowledge of Destination
A person must always have a mental image of his destination before teleporting. This image is acquired by personally visiting the location first (including just viewing it from a distance), having the mental image implanted in one’s mind (by telepathy) by another person who has visited the destination, or by viewing the location through clairvoyance (a viewing task, not simply the easier task of sense plus a successful direction task).
Energy and Momentum
Teleportation involves serious restrictions on movement in order to assure the conservation of energy and momentum. On planetary surfaces teleportation is restricted to jumps of less than regional distance.

Jumps at very distant range involve disorientation for a period lasting from 20 to 120 seconds. Jumps at distant range are hazardous; the teleporter often stumbles or falls upon arrival.

This restriction results from the law of conservation of momentum: on a rotating planet two locations will have different rotational speeds and directions. A jump from a point on Terra's equator to its antipode would result in a total velocity difference between the character and his surroundings of over 3300 kph.

Changes in altitude (actually all movement to locations of differing gravitational potential) will result in potential energy changes manifesting themselves as changes in body temperature.

A jump of 1 km straight down will result in a temperature increase of 2.5 degrees Celsius; this is sufficient to cause extreme fever, brain damage, and even death. A jump up will cool the body by the same amount with equally serious results.

To be safe, a jump may not involve an elevation change of more than 400 meters, and multiple jumps should not involve a cumulative elevation change of more than 600 meters in one hour. These problems may be avoided through the use of technological devices: energy compensators, heat suits, and other means.

[The Mad Monk]

wiki.travellerrpg.com/Teleportation

[The Mad Monk]

httpCOLONSLASHSLASHwikiDOTtravellerrpgDOTcomSLASHt eleportation

There. Replace the CAPS with the proper symbols and paste into your address bar to get the goddamn link this site was blocking for some bassackward reason..

edit: ALSO remove the space between the t and eleportation. It won't let me.

[The Mad Monk]

Anyway, if you remember Traveller as fondly as I do, this is awesome.

Be sure to use the controls on the lower right. Zoom way in and way out. Go wild.

[Cort Haus]

Invoke Bell's non-local connectivity to bind together the points that have moved through time and space.

As someone said above, physically travelling back in time is evidently not possible so the only use for such a thing is in science fiction, where a thin veneer of plausiibility is enough to send the casual reader into a state of suspended disbelief. Of course, the more seriously scientifically minded among the readership will know that it is all a load of bollix so they deal with it (if they are still reading by this point) by stamping "here be dragons" on it. Which is, of course, a coded way of believing anything.

The concept of information moving backwards in time is more interesting though. It literally has a lot less baggage, for a start.

[Lorizael]

TMM, I think I can use my moderator powers to clean all that up if you want.

Invoke Bell's non-local connectivity to bind together the points that have moved through time and space.

So Bell's theorem only seems to rule out "local realism," which means that if we'd like, we can give up reality instead of locality. Some physicists and philosophers of physics think this is a better avenue to go down. Interestingly, there has been some recent work done on retrocausality as a way of dealing with quantum entanglement and other messy violations of Bell's inequalities. So maybe time travel?

[The Mad Monk]

Thanks for the offer, but it was a fine fit of anger and I'd rather keep the monument.