Time Travel: Setup & Challenges for Safe & Accurate Travel

[PeroK]

But time travel to past is not possible according to Einstein's general and special relativity.

This is not true. There is the concept of closed timelike curves (CTCs):

https://en.wikipedia.org/wiki/Closed_timelike_curve

Whether these exotic solutions of the Einstein Field Equations are physically possible is another question. But, the theory permits them.

 

[L Drago]

This is not true. There is the concept of closed timelike curves (CTCs):

https://en.wikipedia.org/wiki/Closed_timelike_curve

Whether these exotic solutions of the Einstein Field Equations are physically possible is another question. But, the theory permits them.

As it is physically not possible, even if we could develop a technology somehow to travel in 90-99 percent speed of light, we will be in future but won't be able to return.

 

[PeroK]

As it is physically not possible, even if we could develop a technology somehow to travel in 90-99 percent speed of light, we will be in future but won't be able to return.

I'm not sure what you mean by that. It's physically possible to undertake a journey from Earth at sufficient relative speed that the differential ageing between the spacecraft and the Earth is significant. Whether human civilization ever achieves this capability is an open question.

 

[L Drago]

I'm not sure what you mean by that. It's physically possible to undertake a journey from Earth at sufficient relative speed that the differential ageing between the spacecraft and the Earth is significant. Whether human civilization ever achieves this capability is an open question.

I am telling it is not physically possible for CTCs to exist probably. You can correct me if I am wrong.

 

[phinds]

The faster we go, the slower time goes for us.

time would pass slowly for us

I'm not clear on whether you are just using shorthand for what actually happens or if you mistakenly believe that time actually does slow down for a traveler. Just to be clear, it does not. The traveler's clock ticks away at the exact same one second per second as the stay at home's clock.

If you do not understand this concept of proper time, then you are making the common mistake of confusing time dilation with differential aging.

 

[L Drago]

I'm not clear on whether you are just using shorthand for what actually happens or if you mistakenly believe that time actually does slow down for a traveler. Just to be clear, it does not. The traveler's clock ticks away at the exact same one second per second as the stay at home's clock.

If you do not understand this concept of proper time, then you are making the common mistake of confusing time dilation with differential aging.

I already know that after travelling in 80-90 percent of speed and returning to earth, our age same but people in earth age would have passed some years.

 

[phinds]

I already know that after travelling in 80-90 percent of speed and returning to earth, our age same but people in earth age would have passed some years.

Which does not quite address the issue I raised, it simply (and correctly) describes the effects of differential aging.

 

[L Drago]

Which does not quite address the issue I raised, it simply (and correctly) describes the effects of differential aging.

A closed timelike curve is a theoretical path where space time is bend in such a way that you can go to past.


The energy required is enormous. It can be created by spinning black holes or something like that.

It is like you start somewhere in time in a CTC and no matter what you end in the same time means theoretically time travel to past is possible and a big thanks to you for changing my perspective.

 

[phinds]

It is like you start somewhere in time in a CTC and no matter what you end in the same time means theoretically time travel to past is possible and a big thanks to you for changing my perspective.

Which (1) is not true and (2) still does not address the issue I raised.

Do you or do you not believe that time slows down for you when you travel?

 

[L Drago]

Which (1) is not true and (2) still does not address the issue I raised.

Do you or do you not believe that time slows down for you when you travel?

I do believe that time slows down for us when we travel due to Einstein's time dilation.

 

[L Drago]

Which (1) is not true and (2) still does not address the issue I raised.

Do you or do you not believe that time slows down for you when you travel?

I was telling it is like a circular loop connection between two points in space time fabric and though we will theoretically be able to time travel in past we will be stuck in that loop forever. Kindly explain where I am wrong. I am asking politely for correction.

 

[phinds]

I was telling it is like a circular loop connection between two points in space time fabric and though we will theoretically be able to time travel in past we will be stuck in that loop forever. Kindly explain where I am wrong. I am asking politely for correction.

AGAIN, my question is, do you or do you not believe that time slows down for you when you travel? I'm just trying to make sure you are clear on this. It has nothing to do with time loops or CTCs.

 

[L Drago]

AGAIN, my question is, do you or do you not believe that time slows down for you when you travel? I'm just trying to make sure you are clear on this. It has nothing to do with time loops or CTCs.

Yes, I believe that time slows down for us when we travel. Time dilation

 

[berkeman]

Yes, I believe that time slows down for us when we travel. Time dilation

https://www.physicsforums.com/insights/geometrical-view-time-dilation-twin-paradox/

 

[L Drago]

https://www.physicsforums.com/insights/geometrical-view-time-dilation-twin-paradox/

Thanks a lot

 

[phinds]

Yes, I believe that time slows down for us when we travel. Time dilation

Thank you for the clarification. You are wrong of course, as you will understand after reading the link that @berkeman provided.

Just to help you understand, think about this. You are now traveling at zero speed relative to the chair you are sitting in, but you are also traveling at a modest percent of the speed of light relative to a slow moving cosmic particle, and you are also traveling at almost the full speed of light relative to a particle moving in the CERN accelerator. You are, in fact, traveling at an infinite number of different speeds, all just depending on finding the right object to correlate your speed to.

In all of these, you are time dilated by different amounts. If your understanding were true then all of these different amounts of time dilation would have to be the same, which is of course mathematically nonsensical.

 

[L Drago]

Thank you for the clarification. You are wrong of course, as you will understand after reading the link that @berkeman provided.

Just to help you understand, think about this. You are now traveling at zero speed relative to the chair you are sitting in, but you are also traveling at a modest percent of the speed of light relative to a slow moving cosmic particle, and you are also traveling at almost the full speed of light relative to a particle moving in the CERN accelerator. You are, in fact, traveling at an infinite number of different speeds, all just depending on finding the right object to correlate your speed to.

In all of these, you are time dilated by different amounts. If your understanding were true then all of these different amounts of time dilation would have to be the same, which is of course mathematically nonsensical.

Thank you. I think I need to read articles from authentic sources like Physics forum than reading articles from random sources in internet and random videos in YouTube which do not give such a clear explanation.

 

[L Drago]

I'm not clear on whether you are just using shorthand for what actually happens or if you mistakenly believe that time actually does slow down for a traveler. Just to be clear, it does not. The traveler's clock ticks away at the exact same one second per second as the stay at home's clock.

If you do not understand this concept of proper time, then you are making the common mistake of confusing time dilation with differential aging.

From reading some sources. I think this is correct.

While travelling at very high speeds time passes normally clock ticks normally for us but very much time is passed on the Earth. Apology I was mistaken earlier that time would tick slowly for us

 

[DonatasA]

I think relative perspective is misunderstood.
Just because you think you are god you will not become god.
Just because you think you are center of universe and all univers is rotating around you, does not mean, univers will start going around you.
You can use this type of thinking for some math and calculations, because many things can be calclulated in realationship with other things, but it will not become real.
If you think photon is not moving, you will not start to move at speed of light. But in calculation of phisics here may not be diffirence who is moving. But this are only math. Not reality.

It is fun to read about time travel, but I don't think it is possible to time travel. Because here are nothing to travel.

Some say, we can travel if we rotate time axes. But it would be same as traveling from work to home.
If we consider traveling from home to work as moving forward, than traveling from work to home would be traveling backward. But reality is, it does not mater direction you are traveling, your movement is always positive. Just because you travel from work to home don't make your inertia negative. Some is time. Here are no direction, here are only movement.

 

[Hornbein]

I have read that the rotating Goedel Universe allows time travel. Observations have shown that our Universe is not rotating.