Is time travel possible and does it mean we have no free will?

In summary: What would you say you are doing?Taken from "Time Travel" threadIn summary, time travel is still a highly debated and speculative topic, with no empirical evidence to support its feasibility. The concept of free will is also a complex and often undefined term, with potential constraints from laws of physics even in the case of time travel. While it may be entertaining to think about, it is important to approach discussions of time travel and free will with a critical and rational mindset.
  • #1
DavidGahan
9
0
"Once confined to fantasy and science fiction, time travel is now simply an engineering problem." Michio Kaku

If time travel were to be operational right now and I want to go 5 days towards the future and record all the events that have transpired, and go back again to the present time, am I correct to assume that I will be seeing the same event unfolding as it was in the future?

If this is so, am I correct to assume that if I were to make a choice right now, someone can travel to the future and see what choices I am going to make even before I made them?

If this is true, am I correct to think that I have no free will since the future already exist?
 
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  • #2
It is very difficult to discuss anything definitive when the premise is based on speculation that lacks any kind of empirical evidence.

I strongly suggest you take what Michio Kaku says with a grain of salt. Whenever you read something like that you quoted, ask yourself this question: has it been empirically verified?! That is what turns something from speculation into science.

If not, we are doing a lot of speculative guesswork, and that is in violation of our PF Rules.

Zz.
 
  • #3
DavidGahan said:
"Once confined to fantasy and science fiction, time travel is now simply an engineering problem." Michio Kaku

If time travel were to be operational right now and I want to go 5 days towards the future and record all the events that have transpired, and go back again to the present time, am I correct to assume that I will be seeing the same event unfolding as it was in the future?

If this is so, am I correct to assume that if I were to make a choice right now, someone can travel to the future and see what choices I am going to make even before I made them?

If this is true, am I correct to think that I have no free will since the future already exist?
If you are basing your questions on what is now known about time dilation, you could (theoretically) take a long trip at a high speed and when you come back you will have aged much less than everything and everyone else remaining on earth, but there is no way to reverse the process. So this has nothing to do with free will and the only sense in which the future already exists is that many things far away have already happened and so by the time the light carries that information to us, it will be in our future but it has already happened.
 
  • #4
One of the problem with debating free will is that nobody ever defines free will. I don't think it's a term that has any meaning.

Note that even Newtonian mechanics raises all the same problems you refer to in #1, since the future can be predicted based on knowledge of the present.

Here are some papers on this kind of thing:

http://authors.library.caltech.edu/3737/
http://authors.library.caltech.edu/6469/
http://arxiv.org/abs/hep-th/9202090
http://arxiv.org/abs/gr-qc/0204022
http://arxiv.org/abs/quant-ph/0506027
http://philsci-archive.pitt.edu/archive/00004240/
David H. Wolpert, Physica D 237, 1257-1281 (2008)

ZapperZ said:
It is very difficult to discuss anything definitive when the premise is based on speculation that lacks any kind of empirical evidence.

I strongly suggest you take what Michio Kaku says with a grain of salt. Whenever you read something like that you quoted, ask yourself this question: has it been empirically verified?! That is what turns something from speculation into science.

If not, we are doing a lot of speculative guesswork, and that is in violation of our PF Rules.
I think you're misinterpreting the rules. Based on the criteria as you've stated them, we wouldn't be allowed to discuss string theory. CTCs exist in solutions to the Einstein field equations. In that sense they are far less speculative than things like supersymmetry and large extra dimensions, which we discuss here all the time.
 
  • #5
Kip Thorne, in his book Black Holes and Time Warps, discusses this sort of thing. He mentions the Novikov self-consistency principle, which is discussed on Wikipedia here: http://en.wikipedia.org/wiki/Novikov_self-consistency_principle. If this principle is correct, then while we do have "free will" in some sense, our free will is constrained by the fact that history has to be self-consistent, even if time travel is included. This doesn't seem implausible to me: after all, our free will is also constrained by many other laws of physics.
 
  • #6
bcrowell said:
One of the problem with debating free will is that nobody ever defines free will. I don't think it's a term that has any meaning.

This may be off topic for physics forums, but have you read Daniel Dennett's books on free will, Elbow Room (1984) and the more recent Freedom Evolves (2003 I think)? IMO he does a good job of giving a consistent definition of "free will", although it's a definition that many people may find unappealing at first, until they go through the details.
 
  • #7
The question of free will is a self-interested thing. Note that people typically want to know if they don't have it, whether they can do as they please or they are silently being guided by a big man in the sky. In that case, it's not a question for physics but for sociology and psychology--it's a question of choice.
 
  • #8
PeterDonis said:
This may be off topic for physics forums, but have you read Daniel Dennett's books on free will, Elbow Room (1984) and the more recent Freedom Evolves (2003 I think)? IMO he does a good job of giving a consistent definition of "free will", although it's a definition that many people may find unappealing at first, until they go through the details.
No, I haven't -- thanks for recommending them!
 
  • #9
Time travel! your time traveling right now!

Time travel doesn't make any sense anymore after SR and GR. In every circumstance I have heard people talk about time travel they keep (either implicitly, or explicitly) referring to an absolute clock. As was pointed out earlier, you can "travel" into the future by just running around your house... But your not traveling into the future because there is no outside time that passes by "faster" while you are running. there are only clocks attached to reference frames. And you and the universe are not the only two clocks...

Right now when you interact with other objects around you house and at school or work, most of them are not at the same "time" as you... some of them are in the past, some in the future... it depends on their temporal momentum E/c, the gravitational field, and whose looking at them...

Keep this in mind.
 
  • #10
jfy4 said:
Time travel! your time traveling right now!

Time travel doesn't make any sense anymore after SR and GR.

It's clear from the context of the OP's post that the OP was referring to CTCs.
 
  • #11
bcrowell said:
It's clear from the context of the OP's post that the OP was referring to CTCs.

This apparent clarity is apparently a relativistic phenomenon!
 
  • #12
I hate being ignorant: what are CTCs?
 
  • #13
ghwellsjr said:
I hate being ignorant: what are CTCs?
CTC = http://en.wikipedia.org/wiki/Closed_timelike_curve"
 
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  • #14
ghwellsjr said:
I hate being ignorant: what are CTCs?

I think that's another term for time travel.
 
  • #15
bcrowell said:
One of the problem with debating free will is that nobody ever defines free will. I don't think it's a term that has any meaning.

Just wanted to know if a person from the future were to visit me, he would know what choices I am going to make even before I made them. Relative to the time traveler, my future is his past.

Here are some papers on this kind of thing:

http://authors.library.caltech.edu/3737/
http://authors.library.caltech.edu/6469/
http://arxiv.org/abs/hep-th/9202090
http://arxiv.org/abs/gr-qc/0204022
http://arxiv.org/abs/quant-ph/0506027
http://philsci-archive.pitt.edu/archive/00004240/
David H. Wolpert, Physica D 237, 1257-1281 (2008)

Thank you for the links especially the "Quantum theory Looks at Time Travel".
 

1. What is the concept of time travel?

Time travel is the hypothetical ability to move backwards or forwards in time, either intentionally or unintentionally. It is a popular topic in science fiction and theoretical physics.

2. Is time travel possible?

Currently, time travel is not possible according to our current understanding of physics. However, some theories such as the theory of relativity and wormholes suggest that it may be possible in the future.

3. Can time travel affect free will?

This is a heavily debated topic among philosophers and scientists. Some argue that if time travel is possible, then our actions in the past can change the present, thus affecting free will. Others argue that time travel would only create alternate timelines, leaving free will intact in each individual timeline.

4. How does the concept of free will relate to time travel?

Free will is the ability to make choices and decisions independently without being influenced by external factors. In the context of time travel, it raises questions about the impact of our actions on the past, present, and future. Some argue that if time travel were possible, it would disrupt the concept of free will as our choices would already be predetermined.

5. Is there any scientific evidence for time travel?

Currently, there is no scientific evidence for time travel. Although there have been some scientific experiments and theories that suggest it may be possible, it is still considered a concept that is purely theoretical and has not been proven or observed in reality.

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