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Old 08-21-1999, 02:49 PM
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I hope this isn't too much like all the other questions on here about time travel, but here goes-
Ok, I heard that if it was possible to travel back in time, you would go be in the 4th dimension (which, they say is time). Does that mean in that dimension every second in history, and in the future is acting itself out right now? How is this possible? Are the people there real? Do you exist there too? If you were to travel back in time and change a major thing, how would it effect now? Like, if you went back to the 18th century, and killed George Washington, would all of democracy just disappear that second? I know these are a lot of questions but I'm so confused!

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Old 08-21-1999, 03:39 PM
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My guess is that time travel is impossible because no one seems to be able to figure out what would really happen!

Some people think that it would be impossible to alter past history (what other kind of history is there?). What's past is past and it is immutable. Others, notably TV science fiction writers, think you could do whatever you want but of course there would be unexpected consequences when (if) you got back to your own time.

Just a clarification on this fourth dimension idea. Time is not considered the fourth dimension -- it just happens to be a very popular one. Using time as a fourth dimension is one of the bases for Einstein's theory of special relativity.

It is possible, and sometimes desirable, to talk about a fourth spatial dimension -- just like the three we are used to only at right angles to all three at once. In fact, there is no mathematical limit to the number of dimensions we can describe this way. Modern physical theories use ten- and twenty-six-dimensional spaces with a straight face. So describing time as the fourth dimension really doesn't add much to the discussion.


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Old 08-21-1999, 03:54 PM
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If time itself were just another dimension, and you could somehow "see" time from the outside, then it would mean that both the past and the future would be fixed from some eternal standpoint. This contradicts human notions of free will, which is why many people feel it can't be that way.

According to one theory, what we experience as time is a progression (happening in a higher-order "metatime") of a boundary in fourth dimensional space-time. Think of dropping a single speck of ice into a mass of supercooled water: the water crystallizes into ice in an expanding front. In this analogy, the ice is the past, the boundary where the water is freezing is the present, and the mass of water an indefinite future.

If this theory is correct, then time travel would be impossible because the past would be "carved in stone", and the future wouldn't exist yet.
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Old 08-22-1999, 04:04 PM
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We Tralfamadorians have laughed, are laughing and will always laugh at you naive humans who are hung up on linearity. You haven't seen, aren't seeing and will never see that all events are coincident. However, we have used, do use and will always use linearity as a silly premise in our sit-coms (ha-ha, Lucy never saw that coming!)

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Old 08-22-1999, 04:17 PM
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ANOTHER time travel question? Don't make me hop into the tardis and give your daddy a Trojan!
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Old 08-23-1999, 01:48 PM
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Time is a DIMENSION. There is indeed a "you" occupying 3-dimensional space at the temporal coordinate known as "8/21/99 at 1:45:17 PM EST". (Think about it: what were you doing then?).

If you imagine yourself sliding backwards along the time continuum to that temporal point...observe that the contents of your mind at that temporal coordinate would (or do), of course, have just as specific a definition as the contents of your pockets then and there, so if "you" could "go back" to 8/21/99 at 1:45:17 PM EST, you would be unaware of ever having experienced 8/23/99 at 2:44:41 PM, because that awareness does not exist in your mind at prior temporal locations.

In other words, the hole in the idea of time travel is the idea that you could "go back" rather than simply "be back" exactly as you were.



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Old 05-17-2020, 08:57 AM
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You cannot travel into the past because it isn't there anymore.


In order for someone to travel into the past, they would need to return every atom in the universe back to the position that it was at the time in the past that you are going to, twith every atom in the same energy state.... including those atoms that have become part of your body, such as the ones in food water and air. You cannot go back in time to a situation where there are two sets of the same atoms as it violatrs the Law of Conservation of Mass. You can travel imto the future, we are all doing that right now. The unanswered question is can you arrive at a place in time in the future. 100 years before everyone else you know while still remaining the same age. I would also think this an impossible achievement.... Only light can travel at the speed of light.
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Old 05-17-2020, 10:09 AM
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It may be impossible to travel back in time, but replying to 21-year-old threads might be considered a form of time travel...
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Old 05-17-2020, 10:11 AM
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There was a thread started about this just next week.
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Old 05-17-2020, 10:32 AM
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There was a thread started about this just next week.
In _your_ frame of reference.
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Old 05-17-2020, 11:54 AM
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Does that mean in that dimension every second in history, and in the future is acting itself out right now?
No, because that's not what 'now' means.
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Old 05-17-2020, 01:12 PM
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Originally Posted by Mangetout View Post
No, because that's not what 'now' means.
In this case, "now" means 1999.

And Sonic hasn't posted for 20 years and 3 days. Happy anniversary of your non-participation, Sonic!

Last edited by CookingWithGas; 05-17-2020 at 01:13 PM.
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Old 05-17-2020, 01:19 PM
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Substantial changes to the past are probably impossible because time will fill in the gaps. If someone went back in time, say, and killed George H. W. Bush as a young boy, that wouldn't mean that Reagan had no Vice President or that we wouldn't have had a 41st or 43rd president. Someone else would have filled those rolls.

However, minor changes could occur and many people might have lived who would have otherwise died or vice versa. Someone could be doing this even now and one of the people affected could vanish right in the mid
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Old 05-17-2020, 02:05 PM
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With a thread this ancient, it's better to just start a new one, if you want actual discussion. I'll close this one.
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