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Gnostic Mom

Is there a logical contradiction here?

A: Wouldn't it be great if modern technology could develop time travel? Travel to the future, revisit your past, etc. Exciting!

B: Indeed, but unfortunately logically impossible. The future, by definition, does not exist in the present. Neither does the past. Think about it. You get into your time machine, and travel to the past AFTER you have pulled the lever. See the problem?


asked on Monday, Oct 25, 2021 12:10:59 PM by Gnostic Mom

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Gnostic Mom writes:

"Time" travel is a misnomer.  In order to move about in time, one must also move in space.  A more accurate term would therefore be "space-time travel".  Regardless of "when" you might arrive in the past, the painstaking calculations necessary to allow you to arrive at an absolutely precise and safe location are, I think, prohibitive.  So when you get into your time machine and pull that lever, you are most likely going to arrive in the past floating around in the middle of space.  And regardless of the method of activating your time machine, you are still going to arrive in the past "after" you have activated it.  That's why it's called "the past".

posted on Tuesday, Oct 26, 2021 03:28:52 PM

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Answers

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Bo Bennett, PhD
3

Word games. We all travel to the future every day... in real time. When we arrive, the future becomes the present for us. For all practical purposes, we can (and do) travel to the future. Although we don't travel back in time, logically, the same word games apply here.

answered on Monday, Oct 25, 2021 12:48:34 PM by Bo Bennett, PhD

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TrappedPrior (RotE) writes:

They probably meant something like 'fast travel'. We're in 2021, but you can press a button/flip a switch/pull a lever/whatever and 'teleport' to 2022, for instance, instead of having to wait out the rest of the year.

But your answer - though unexpected - is actually a good one, I think. It is a word game, since the future is technically any unseen time forward from the current point in time. Yesterday, I thought about today, and 24 hours later, I arrived at it. 

posted on Monday, Oct 25, 2021 01:42:53 PM
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Bo Bennett, PhD writes:
[To Rationalissimus of the Elenchus]

If they meant fast or instant travel, I would still argue it is a problem with linguistics at best. "Future" by definition means what it does because that's the meaning we gave it. Clearly, none of us understand time travel so we can't conflate the logical impossibility of time travel with the the words we use for time travel having logical problems. The best analogy I can think of on the spot the "married bachelor." We can take a bachelor and marry him off, but then he is no longer a bachelor. "The future, by definition, does not exist in the present..." right, but when in the future, it is no longer the future and is now the present.

For any more clarification on this matter, I refer you to Dr. Emmett Brown.

[ login to reply ] posted on Monday, Oct 25, 2021 01:49:24 PM
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Jason Mathias
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I see no contradictions here. 

Time is relative to the observers inertial reference frame. So someones future can exist in someone else present. But for both of them, they can only ever exist in their own present. This kind of time travel where you could go into the future and see yourself would have to create two of you so that the relativity of time travel can take place. So it wouldn't just be time travel, but also a cloning technology too. 

answered on Tuesday, Oct 26, 2021 03:18:48 PM by Jason Mathias

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